ITJEMAST V02(3) July 2011
description
Transcript of ITJEMAST V02(3) July 2011
IN THIS ISSUE
Thermal Comfort Assessment to Building Envelope: A Case Study for New Mosque Design in Baghdad
A Practical Step towards Integrating Elderly Pathway Design into Museum Space Planning: Framework of Satisfaction Assessment
Validating Measurements of Perceived Ease Comprehension and Ease of Navigation of an Online Learning Technology: Improving Web Based Learning Tool Adoption and Use
A Land Data Assimilation System Utilizing Low Frequency Passive Microwave Remote Sensing: A Case Study of the Tibetan Plateau
Prediction of Weld Pool Geometry in Pulsed Current Micro Plasma Arc Welding of SS304L Stainless Steel Sheets
Habitability Study on Low-Cost House Design of Modern and Traditional Mid-rise House Units in the City of Mukalla, Yemen
Interrelationships between Characteristic Lengths of Local Scour Hole
Oxygen Excess Control of Industrial Combustion Through the Use of Automotive Lambda Sensor
International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
Cover photo is copyrighted by Dr. Wataru Takano and Professor Dr. Yoshihiko Nakamura. Humanoid robots, NAO, are being used for Undergraduate Mechanical Engineering Seminar at Department of Mechano-Informatics, University of Tokyo. (Photo is used with permission).
Volume 2 Issue 3 (July, 2011) ISSN 2228-9860 eISSN 1906-9642 http://TuEngr.com http://Go.to/Research
International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
http://TuEngr.com, http://go.to/Research
International Editorial Board
Editor-in-Chief Boonsap Witchayangkoon, PhD
Associate Professor, Thammasat University, THAILAND
Honorary Board: Professor Dr.Mikio SATOMURA (Shizuoka University, JAPAN) Professor Dr.Chuen-Sheng Cheng (Yuan Ze University, TAIWAN) Professor Dr.I Nyoman Pujawan (Sepuluh Nopember Institute of Technology, INDONESIA) Professor Dr.Neven Duić (University of Zagreb, CROATIA) Professor Dr.Lee, Yong-Chang (Incheon City College SOUTH KOREA) Professor Dr.Phadungsak Ratanadecho (Thammasat University, THAILAND) Associate Prof. Dr.Uruya Weesakul (Dean of Faculty of Engineering, Thammasat University, THAILAND )
Associate Editors: Associate Prof.Dr. Ahmad Sanusi Hassan (Universiti Sains Malaysia, MALAYSIA ) Associate Prof. Dr. Paulo Cesar Lima Segantine (University of São Paulo, BRASIL) Associate Prof. Dr. Kurt B. Wurm (New Mexico State University, USA ) Associate Prof. Dr. Truong Vu Bang Giang (Vietnam National University, Hanoi, VIETNAM ) Associate Prof. Dr.Narin Watanakul (Thammasat University, THAILAND) Dr.H. Mustafa Palancıoğlu (Erciyes University, TURKEY)
Editorial Research Board Members Associate Prof.Dr.Peter Kuntu-Mensah (Texas A&M University-Corpus Christi, USA) Associate Prof.Dr. Anchalee Jala (Thammasat University, THAILAND ) Associate Prof. Dr. Masato SAITOH (Saitama University, JAPAN ) Assistant Prof.Dr. Zoe D. Ziaka (International Hellenic University, GREECE ) Associate Prof.Dr. Supornchai Utainarumol (King Mongkut's University of Technology North-Bangkok, THAILAND) Associate Prof.Dr.Chavalit Chaleeraktrakul (Thammasat University, THAILAND ) Associate Prof.Dr.Krittiya Lertpocasombut (Thammasat University, THAILAND ) Associate Prof.Dr. Bovornchok Poopat (King Mongkut's University of Technology Thonburi, THAILAND ) Assistant Prof.Dr. Akeel Noori Abdul Hameed (University of Sharjah, UAE) Assistant Prof.Dr. Atch Sreshthaputra (Chulalongkorn University, THAILAND) Assistant Prof.Dr. Rohit Srivastava (Indian Institute of Technology Bombay, INDIA) Assistant Prof.Dr. Watanachai Smittakorn (Chulalongkorn University, THAILAND ) Assistant Prof.Dr. Kitjapat Phuvoravan (Kasetsart University, THAILAND) Assistant Prof.Dr. Khiensak Seangklieng (Thammasat University, THAILAND ) Assistant Prof.Dr. Chainarong Chaktranond (Thammasat University, THAILAND ) Assistant Prof.Dr.Kridayut Chompoming (Thammasat University, THAILAND ) Assistant Prof.Dr. Nopporn Leeprechanon (Thammasat University, THAILAND ) Assistant Prof.Dr. Sawat Pararach (Thammasat University, THAILAND ) Assistant Prof.Dr.Winai Raksuntorn (Thammasat University, THAILAND ) Assistant Prof.Dr. Watit Pakdee (Thammasat University, THAILAND ) Assistant Prof.Dr. Cattaleeya Pattamaprom (Thammasat University, THAILAND ) Dr. David Kuria (Kimathi University College of Technology, KENYA ) Dr.Isares Duchallaya (Thammasat University, THAILAND ) Dr.Puttipol Dumrongchai (Chiangmai University, THAILAND ) Dr.Bandit Suksawat (King Mongkut's University of Technology North-Bangkok, THAILAND ) Dr. Foong Swee Yeok (Universiti Sains Malaysia, MALAYSIA) Dr.Orawan Chunhachart (Kasetsart University Kamphaengsaen Campus, THAILAND) Dr. C. Raza Mirza (UK )
2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies.
International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies (ITJEMAST) (ISSN 2228-9860) is published quarterly by TuEngr Group @ Faculty of Engineering, Thammasat University, Klong-Luang, Pathumtani, THAILAND 12120. Periodicals postage paid at Pathumtani, THAILAND. Correspondence: All correspondence should be addressed to Dr.Boonsap Witchayangkoon, Faculty of Engineering,
Thammasat University, Klong-Luang, Pathumtani, THAILAND 12120 or [email protected].
i
:: International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
Volume 2 Issue 3 (July, 2011) ISSN 2228-9860 http://TuEngr.com, http://Go.To/Research eISSN 1906-9642
FEATURE PEER-REVIEWED ARTICLES
Thermal Comfort Assessment to Building Envelope: A Case Study for New Mosque Design in Baghdad 249
A Practical Step towards Integrating Elderly Pathway Design into Museum Space Planning: Framework of Satisfaction Assessment 265
Validating Measurements of Perceived Ease Comprehension and Ease of Navigation of an Online Learning Technology: Improving Web Based Learning Tool Adoption and Use 287 A Land Data Assimilation System Utilizing Low Frequency Passive Microwave Remote Sensing: A Case Study of the Tibetan Plateau 303
Prediction of Weld Pool Geometry in Pulsed Current Micro Plasma Arc Welding of SS304L Stainless Steel Sheets 325
Habitability Study on Low-Cost House Design of Modern and Traditional Mid-rise House Units in the City of Mukalla, Yemen 337
Interrelationships between Characteristic Lengths of Local Scour Hole 355
Oxygen Excess Control of Industrial Combustion Through The Use of Automotive Lambda Sensor 365
2012 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies.
:: International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
http://TuEngr.com
Call-for-Papers:
ITJEMAST invites you to submit high quality papers for full peer-review and possible publication in areas pertaining to our scope including engineering, science, management and technology, especially interdisciplinary/cross-disciplinary/multidisciplinary subjects.
Next article continue on next page
*Corresponding author (Dr. Akeel Noori Abdul Hameed). Tel: 0097165050992. Fax: 0097165050982 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/249-264.pdf
249
International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
http://www.TuEngr.com, http://go.to/Research
Thermal Comfort Assessment to Building Envelope: A Case Study
for New Mosque Design in Baghdad
Akeel Noori Abdul Hameed a*
a Department of Architectural Engineering, College of Engineering, University of Sharjah, UAE
A R T I C L E I N F O
A B S T RA C T
Article history: Received 12 February 2011 Received in revised form 13 April 2011 Accepted 20 April 2011 Available online 01 May 2011 Keywords: Thermal Comfort; Building Envelope Assessment
The work is carried out with an objective of first, evaluating: the thermal characteristics of opaque and transparent parts of the building envelope in hot dry climate of case study “new mosque” building in Baghdad, the impact of sol-air temperatures, heat gain factors and the u-value of envelope section components. Second, it aims to assess the architectural criteria for appropriate passive design of new mosques in hot dry climates. Architectural design and construction of the new mosque (musalla) envelope in Baghdad are thermally inefficient in protecting the indoor space from climatic fluctuations. Therefore, the existing new mosques are not within thermal comfort level. To achieve and maintain that, applying architectural and construction alternatives on the mosque envelope contributes to controlling heat exchange through it as well as enhancing its thermal behaviors that contribute to getting internal thermal balance. The research covers survey of design, construction features, comfort levels in new mosques, and definition of the “model mosque”, as well as identification and thermal assessment of the typical “model mosque”. Computer simulations for building thermal behavior and design modification of building construction components also covered by the research. The findings and conclusion of the impact of simulation changes stated as well as recommendations for possible future mosque and design strategy. The findings show that HVAC systems entail capital, functional and maintenance costs whereas the passive mosque (musallas) building consumes less energy as well as being more likely to be in sympathy with the environment.
2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Some Rights Reserved.
2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. 2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies.
250 Akeel Noori Abdul Hameed
1. Introduction Architectural design is influenced by the actual thermal behavior of building components,
and this depends not only on their steady and periodic thermal characteristics but also on
exposure effects, orientation, surface features and the climate parameters of the location.
The main issue of this research is “the thermal comfort for internal space of the modern
mosque in Baghdad”. The mechanical and electrical systems of heating and cooling encourage
architects to implement new construction techniques and using wide openings in buildings'
facades as well as employing new constructional materials, which are not suit local hot climate.
All this makes people depends on HVAC systems, which consume high amounts of energy
annually in an attempt to provide a comfortable indoor environment. The mosque buildings are
affected by the adoption of new materials and new urban planning as well as new architectural
designs, which are not sensitive to the environment, the actual needs of occupants, and the
building function or comfort criteria. (Tappuni, 1973).
The new city of Baghdad nowadays includes individual multi-storey buildings. Wide
streets and open spaces expose those buildings more to solar radiation and other types of
climatic impact more than the other traditional buildings, which are surrounded by narrow
alleyways. It can be concluded that for buildings in a hot-dry climate, minimizing the external
heat gain through the building envelope would be a good strategy to reduce the dependence on
energy in conditions of necessity. That can be achieved by means of appropriate design for the
building envelope.
The research is carried out with the objectives of evaluating thermal characteristics of the
new mosque “musalla” envelope in Baghdad, the impact of sol-air temperatures, heat gain
factors and the U-value of envelope section in aims to assess the generational architectural
criteria for appropriate passive design of mosques.
The research discusses the thermal comfort in the new “musalla” in Baghdad, which is
effected by heat exchange that influenced by its orientation, envelope design, structural and
constructional components as well as the specifications and use of materials in order to:
i. Investigate the impact of envelope components on the heat exchange and thermal
comfort of the users of inner environment of the new mosque (musalla).
ii. Investigate the thermal efficiency of the present new mosque envelope in Baghdad.
*Corresponding author (Dr. Akeel Noori Abdul Hameed). Tel: 0097165050992. Fax: 0097165050982 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/249-264.pdf
251
iii. Study how to minimize the “environmental impact” by revising the design and
materials of the envelope.
iv. Identify the optimum thermal design “passive design” and construction materials
specifications and details for the new mosque envelope.
v. Propose other suitable treatments, which affect thermal design for the mosque that
provides thermal comfort for the occupants and reduces energy consumption at the
same time.
vi. Optimize comfort level for occupants for five prayer times.
As beginning a new paragraph, a line is leaved blank before starting a new paragraph
(Satomura et al., 2013). All references must be mentioned in the writing article.
2. Background of the Research
2.1 Baghdad Climate Generally, the climate of Iraq is characterized by a large diurnal air temperature range
coupled with a high intensity of incident solar radiation as shown in Figure 1 On the other
hand, in such widely fluctuating climates, building envelope has great potential in providing
thermal comfort and reducing energy consumption. An efficient thermal design of a building
envelope should consider three main parameters which are; First the form and orientation of
the building, Second; the fenestration, which relate to the size, orientation and exposure of the
windows to the sun and the type of glazing and Third; the thermal properties of the opaque
elements. This includes the solar absorptance of the external surfaces and the thermal capacity
and conductance of the elements as well.
Climatic information, including air temperature and solar intensity in the Baghdad region,
as well as thermal air rates, humidity and other parameters were obtained from the Iraq
Forecast Directory-Baghdad. It has been arranged with the Building Research Center in
Baghdad to get the outputs of some tests carried out by the center’s instruments, which help in
furnishing this research with some important information.
2.2 Problem Statement Due to the defined daily uses of mosques, the problem facing architects and engineers is
how to achieve thermal comfort during prayer times when the mosque building is occupied.
The short time of each of the five daily prayers (almost 30 minutes per prayer) gives rise to
252 Akeel Noori Abdul Hameed
serious problems in terms of providing comfort. It is noticed that it is not enough to reach
comfort level even though an HVAC system is used and just operates before each prayer time.
It would be too costly also to operate it for a long period before prayer times to provide
comfort for very short periods of prayer.
One of the important characteristics of the mosque design is the orientation of Mecca
(Qibla direction), which considered as a constant design parameter for the mosque.
Figure 1: Annual Temperature in Baghdad, Source: Baghdad Metrological Dept.2000.
The thermal properties of the envelope are determined by the combination of wall mass,
thermal resistance; insulation location, external surface colour and texture, and the size and
location of glazing. All of those affect energy consumption differently according to weather
conditions. The design of the building envelope can also greatly affect infiltration rates.
Based on the previous highlighted design features and specific climate parameters, the
problems of the new mosque in Baghdad may be summarized as following:
i. Lack of optimum passive design guidelines for the mosque’s envelope which influence
the comfort level of the inner environment and contribute for energy conservation.
ii. Ignoring comfort level requirements for occupants which influenced by construction
materials and details used in buildings as well as the suitable architectural treatments in the
new mosques building design in Baghdad.
*Corresponding author (Dr. Akeel Noori Abdul Hameed). Tel: 0097165050992. Fax: 0097165050982 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/249-264.pdf
253
3. Research Method The research has considered the following steps:
i. Achieving specific survey to ascertain whether it is true or not that the new mosque
building in Baghdad is not comfortable thermally for occupants.
ii. Defining the weaknesses in the design and construction components of the mosque
through the following strategy:
a. Collecting data from 50 new mosques in Baghdad that represent 65% of the new
mosques in the Baghdad vicinity in July 2008.
b. Identification of the typical new mosque, “Model Mosque”, in Baghdad.
ii. Applying an analytic study and assessment for architectural and construction
components relating to heat exchange through the envelope of the “Model Mosque” in
Baghdad, which is determined according to the common architectural and constructional
elements in fifty new mosques in Baghdad, using heat balance equation.
iv. Assessment for the “Model Mosque” using a computer simulation program (BLAST
program) before and after introducing changes to the total transparent area of its envelope and
the construction features.
The BLAST (Building Loads Analysis and System Thermodynamics) system is a set of
computer programs for predicting heating and cooling energy consumption in building.
One of the BLAST processors, Heat Balance Loads Calculator (HBLC), is used to
interactively create BLAST input files with a minimum of input required from the user.
4. Definition of “Model Mosque” A survey to define the “Model mosque “musalla” and determine the architectural and
constructional features of the new mosque envelope as well as thermal comfort response for the
praying people in those fifty new mosques is the main aim before starting thermal assessment.
The conclusion of the survey output gave the architectural characteristics and other
constructional details of the typical new mosque in the Baghdad vicinity the “Model Musalla”,
which is considered as representative the typical design of new mosques for use in the
computer simulations.
The typical “musalla” or “praying area hall” within mosque “complex” that has other
facilities”, has the same specifications as all the modern types in Baghdad. It was found that
254 Akeel Noori Abdul Hameed
these specifications are the following:
i. The musalla has a detached rectangular form with inside net-dimensions in general
22mx11mx6m in height. It includes a central dome at the roof, the diameter of which is 7.0m
and the height of which from the base to the top of the cone is 6.5m. This rectangular shape has
one attached arcade laid at the same longitudinal wall, which is parallel to that which faces the
“qibla” or Mecca (the holy city in Saudi Arabia) see Figure 3.
ii. The main feature of the musalla mass is the dome which lies in the center of the roof.
The dome has three levels from bottom to top. The first part is the drum (dome base). Its height
is 2.00m. Above it there is a spherical part and the upper part is the cone.
13
52
4
67 8
9
1 0
1 1
1 2
1 4
1 51 6
1 7
1 8
2 0
2 12 2
2 3
2 4 2 5
2 6
2 7
2 8
2 9
3 0
3 13 2
3 3
3 4
3 5
3 6
3 7
3 8
3 9
4 04 1
4 2
4 3
4 4
4 5
4 64 7
4 8
4 9
5 0
1 3
1 9
F in d e n c lo se d f t h e d e ta i ls o t h e M o sq u e s s u rv e y f ro m 1 to 5 0
S U R V E Y O F F IF T Y N E W M O S Q U E S IN B A G H D A D
IN 1 9 9 7
IR A Q
Figure 2: Location of fifty surveyed new mosques in Baghdad.
All these components are usually found in the typical Baghdadi mosque’s dome. Four
columns support the dome from inside praying hall; the average thickness of its concrete slab is
0.15m and includes eight small arcade windows normally situated on the drum part of the
dome.
iii. The musalla is usually constructed from a reinforced concrete skeleton structure with
brick wall partitions. The roofing slab thickness is 0.15m, and the brick wall is 0.24m thick.
Above the concrete slab of the roof there are many layers which consist of the waterproof layer
(0.07m), natural clean sand (0.15m) and rough sand (0.05m) and cement tiles (0.03m). The
dimensions of each cement tile are 0.80mx0.80m. The interior finishing of the dome and the
*Corresponding author (Dr. Akeel Noori Abdul Hameed). Tel: 0097165050992. Fax: 0097165050982 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/249-264.pdf
255
walls is fine gypsum, and its thickness is 0.025m.
Figure 2a: Plan for the Model Mosque “Musalla”.
5. Research Considerations Fundamental research considerations for the “Model Mosque” features are:
1. musalla envelope is one piece.
2. The collected data did not refer to the existence of any space beneath the musalla.
3. The musalla envelope consists of just external Walls, Roof and Floor.
4. Sub-parameters, windows, and doors “Transparent Part” are represented as part of the
envelope.
5. Air vents, as uncontrolled openings do not exist.
6. The minaret “the tower” still has no role in the thermal behavior of the new musalla
envelope.
7. Average number of praying persons per prayer time for the five daily prayers is 30,
becoming sometimes 45 at peak time at sunset prayer “maghrib prayer”.
8. Air cubage is represented by the human comfort zone that is within 8 feet in height and
the remaining volume of the internal space of the musalla.
9. It is proposed that the inner environment of the “Model musalla” is in thermal balance
to estimate the actual ability of the musalla envelope to maintain that balance. The
present research discussed, by means of geometrical analytical study, all parts of the
musalla envelope to highlight the role of each, area of opaque and transparent parts, and
256 Akeel Noori Abdul Hameed
study for the dome parts as well as defining the air cubage.
10. Heat exchange estimate by heat flow mean per sq.m through walls, windows and roof
as well as heat flow mean by ventilation per m³ owing to the successful results from
thermal computer simulations and approach, which have been considered.
The new mosque type in Baghdad is representative of the mosques built after World War
II and shares the following characteristics:
1. Located in the Baghdad vicinity.
2. Used usually on five short occasions daily.
3. Its building is passive designed.
6. Results
6.1 Computer Simulation The “Model musalla” building as shown in Figure 3 has been simulated for the four
different roof and five different walls structures. To make the simulations comparable, the size
of one huge space or praying hall (musalla) and its direction to Mecca at 10 degree southwest
has been treated as a constant.
6.2 Simulation Alternatives Applications
6.2.1 Walls Simulation Analysis a. The computer simulation proved that the massive envelope behaves as a “Thermos
Flask”. So, there is no an actual enhancement for thermal comfort level of the inner
environment after increasing wall thickness more than 36cm or even using cavity walls with
the same specifications of the “Model Musalla” envelope, Figures 4, 5, and 7.
b. It appears that the musalla building is dialectically balanced with the outside climate for
a wall thickness of 36 cm because as the wall thickness decreases below 36cm its effectiveness
in damping outside temperature fluctuations also decreases. On the other hand, for wall
thickness more than 36cm, the heat received during the long summer day cannot be released
during the shorter nighttime according to expected long “Time Lag”, which causes bad
envelope behaviors in terms of “Thermos Flask” manner. In this case, there is overlapping heat
gain occurrence which a raises the inner air temperature.
c. The inner environment of the musalla’s building is balanced with the outside climate
*Corresponding author (Dr. Akeel Noori Abdul Hameed). Tel: 0097165050992. Fax: 0097165050982 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/249-264.pdf
257
when the wall thickness is 36cm, but it is influenced more by climatic fluctuations when there
is a thin envelope of 12cm thickness.
6.2.2 Roof Simulation Analysis The computer simulation also indicates, that the traditional RC (Reinforced Concrete) flat
roof still perform the best thermally, and has positive heat exchange after the applying of
additional insulation material (15cm), Figures 6, 8 and 9.
Figure 3 This graph shows that the radiation peak time in Baghdad starts at 10.30 am and increases gradually to reach a maximum at 3.00 pm, and reduces gradually after that to reach starting point at 7.00pm. However, the inner temperature increases from 1.00 pm gradually till 10.00 pm, that indicates the important role of the envelope in delaying the heat gain from reaching the inner space, or what is called –Time lag period–which depends on the envelope section in terms of the specifications of material and constructional details. The lowest curve indicating the comfort level ranges
Figure 4a: Building envelope behavior before applying simulation.
Figure 4 Range of Comfort Level in Iraq
258 Akeel Noori Abdul Hameed
Figure 4b: Building envelope behavior before applying simulation.
Figure 5: Building envelope behavior after reducing glazing area to half.
Figure 6: Building envelope behavior after reducing glazing area to half.
*Corresponding author (Dr. Akeel Noori Abdul Hameed). Tel: 0097165050992. Fax: 0097165050982 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/249-264.pdf
259
Figure 7: Building envelope behavior using different types of roof.
Figure 8: Building envelope behavior using different types of roof.
Figure 9: Building envelope behavior using different types of roof.
260 Akeel Noori Abdul Hameed
Figure 10 Building envelope behavior using no glass area at west& east
7. Discussion Achieving and maintaining thermal comfort level for the indoor environment of the
mosque “musalla” by applying architectural and construction alternatives on the musalla
envelope will contribute controlling heat exchange through it as well as enhancing the thermal
behaviors of its construction components.
The findings are showing that HVAC systems mean capital, functional and maintenance
costs for passive musalla building consumes less energy. It is more likely to be in sympathy
with the environment also.
The specific research findings are concluded as follows:
1. Architectural Design of the present new mosque “musalla” envelope in Baghdad is
thermally inefficient according to the previous analytical assessment and computer simulation.
2. Materials used in the construction of the envelope of the new musalla are not thermally
efficient in protecting the indoor environment from climatic fluctuations.
3. Then, the indoor environment of the present new musalla is not recently within thermal
comfort level.
4. It appears that the indoor environment of the musalla building is thermally balanced
with the local climate for a wall thickness of 36cm; highly insulated typical RC flat roof, avoid
the transparent area at west and east as well as reducing it at South-west orientation to be half
of transparent area of the “model musalla”.
5. It is found also that the indoor environment of the musalla’s building is influenced more
*Corresponding author (Dr. Akeel Noori Abdul Hameed). Tel: 0097165050992. Fax: 0097165050982 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/249-264.pdf
261
by climatic fluctuations when there is a thin envelope (less than 30cm thickness), and the
envelope’s behaves as a “Thermos Flask” when there is a massive envelope (more than 36cm
thickness).
6. During the past ten years it has not been economically feasible to invest in HVAC plant
for mosques to meet the running costs. It is not likely that this economic situation in Iraq will
change in the near future and undoubtedly many mosques will have to be built with these
economic constraints. So, this study has not considered the totally dependence on centralized
HVAC systems as part of any strategy to achieve thermal comfort.
7. Achieving as well as maintaining thermal comfort for the indoor environment of the
present new musalla should come from controlling heat gain and enhancing external
microclimate. The following factors should be taken into consideration as recommendations
and techniques to be applied:
i. Selecting materials and construction system on the basis of low thermal transmittance
(low U-value) and high thermal mass in addition to the implementation of
constructional treatments and alternatives to get a desired time lag within 8 to 14 hours
for walls, and 20 to 30 hours for the roof. Using well-insulated roofing materials to
provide high time lag, low thermal transmittance and high thermal capacity (like local
fershi brick 30cmx30cmx5cm) and 0.36m walls thickness to replace 0.24m walls, or
foaming Portland cement mixture with a foaming agent such as aluminum dust to make
insulated light concrete roof slab could be also more effective in controlling heat flow.
ii. Using the most common economical thermal insulation materials in Baghdad, that is,
polystyrene (11 cm) thick for the roof; (7 cm) thick for south-facing walls;(8 cm) for
southeast walls; and (10 cm) for other orientations. Insulation material should be
located near the external layer of the walls, which should be smooth and painted
externally in light colors.
iii. Designing well-shaded walls and windows, selecting suitable window insulating Low-
e-glass and size for each orientation, these areas should be minimal on the east and west
elevations.
v. Raising the roof enables cooling by ventilation; the best U-value for the whole roof and
ceiling construction should be 0.8 W/sq.mc.
v. Using double roof, double walls skin and the early development ideas on "Filter"
Architecture" to get high thermal protection will give an additional protection for
indoor environment.
vi. Designing the musalla to be in thermal contact with the earth, the idea of (sub ground
262 Akeel Noori Abdul Hameed
level–basement) enables benefits from the cooled humid space more than is possible at
ground level.
vii. Additional ventilation is required in summer using fans. This can be beneficial,
particularly at nighttime, and daytime in shaded spaces. Further research is needed on
the optimal mix of natural ventilation, the simple mechanical fan, and water nozzle fan.
viii. Employment of an L-shape or U-shape Riwaq (semi-covered arcade area) attached to
the musalla envelope gives it more shade, and enhances the microclimate. In addition,
an increase in the numbers of domes is thermally desirable for more benefits from
buoyancy phenomena occurrences that generate more passive ventilation through the
dome and envelope openings.
ix. Employing of minarets as external breeze catchers (Air Scoop). The inlet openings of
minarets should face the prevailing pleasant northwest wind in Baghdad to promote
airflow into the musalla, using the convective and evaporative cooling techniques for
elevating internal comfort level in such harsh summer in Baghdad.
x. Microclimate planning controls can have a major effect over the musalla design. In
addition to providing shade, plants can assist cooling by evaportranspiration. Plants also
enhance the visual environment and create pleasant filtered light.
xi. The study will be transferable for other parts of Iraq with certain limitations. For
example, in the southern part of Iraq increase in temperature could be consummated
either by introduction of some cooling or an increase in the thermal mass. In the north,
which is generally cool, this may be consummated of some heating or an increase in
insulation and a reduction in glazed area.
8. Conclusion The existing musalla is effectively a passive building. Based on that, there is no
consideration for HVAC systems. The musalla building will be dialectically balanced with the
outside climate for a wall thickness 36 cm because as the wall thickness decrees below 36cm
its effectiveness in damping outside temperature fluctuations also decreases.
For wall thickness more than 36cm, the heat received during the long summer day can not
be released during the shorter nighttime that brings overlapping heat gain occurrence which
raises the indoor air temperature. The computer simulation also indicates, that the traditional
RC (Reinforced Concrete) flat roof still the best thermally in terms of cost, available labor skill
in Baghdad, and positive heat exchange as well that will be more suitable after applying of
additional insulation material (15 cm ).
*Corresponding author (Dr. Akeel Noori Abdul Hameed). Tel: 0097165050992. Fax: 0097165050982 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/249-264.pdf
263
Passive Mosque (Musalla) building design must take into account the following;
i. Indoor Thermal comfort requirements.
ii. Limitations of local construction, climate, available materials and labor skills.
iii. Specific nature of activity.
v. Capability of building envelope for protecting the indoor environment of the musalla
from climatic fluctuations.
vi. Consideration of high thermal mass envelope, insulation and other criteria that
influence heat exchange and Time-Lag.
vii. Microclimate impacts as well the pattern of the surrounding urban fabric, vegetation
and landscape.
viii. Construction capability that play direct role in heat flow.
ix. How all the previous criteria affect the economic factor that represents a major
parameter in taking design decisions?
9. Acknowledgements First of all, I would like to thank my university for providing full support including
financial support, which is the most needed for this project to be achieved. My sincere thanks
go also to all the field assistants, without whom this research would not have been realized.
Very special thanks are due to Professor Dr. Peter Woods (Malaya University, Malaysia), as
well as Associate Professor Dr. Ahmad Sanusi Hassan (Universiti Sains Malaysia), and
Assistant Professor Dr. Atch Sreshthaputra (Chulalongkorn University, Thailand) for their
insightful comments, helping clarifying and improving the manuscript.
10. References Al-Azawi, Muhyi.(1984). The Passive Internal Temperature of Buildings for Different Design
Conditions in Iraq. (Proceeding of Scientific Research Council-Baghdad Research Center, Building Materials Department-Baghdad-Iraq, Vol.2. Symposium of Thermal Insulation in Hot-Dry Climate, 26-28 Nov. 1984), Baghdad.
Al-Riyahi, Mehdi and Akrawi, A. (1995). Evaluation of Direct and Total Solar Radiation on Surfaces with Different Orientation in Baghdad during Cloudless Days. Journal of Solar Energy Research, Vol.3, No.1, Building Research Center, Baghdad.
Al-Umary, Hafsah Ramzy (1988).Modern Architecture of Mosques in Iraq: Analytic Field Study for Baghdad Mosques since Second World War, Unpublished M. Sc. Thesis (in Arabic) submitted to the University of Baghdad.
ASHRAE 55-1992,(1992). ASHRAE standard-Thermal Environmental Conditions for Human Occupancy, Atlanta: American Society of Heating, Refrigerating and Air-conditioning
264 Akeel Noori Abdul Hameed
Engineers, Inc.
Bomberg, M. & W.C. Brown, (1993). Building Envelope and Environmental Control, Part I & II, published in ,construction Canada35 (1),1993,P.15-18.
CIBSE AM13 (2000) .Chartered Institute of Building Services Engineers, UK
Climatology Atlas No.II for Iraq (2006), Baghdad. Metrological Department, Ministry of Communications, Baghdad
Dawud, Azhar J.(1983). Passive Approaches to Solar Architectural Design for Iraq, Unpublished M.A. thesis submitted to the University of Sheffield,UK.
Fanger, P.O (1970). Thermal Comfort: Analysis and Applications in Environmental Engineering, McGraw-Hill Book Company, Kopinhagen.
Shaaban, Dr. A.C. and Jawadi, Dr. M.(1973). Analysis of the Climate of Iraq: It's Impact on the Building Character, R.p. 21/73., Building Research Center, Baghdad.
Straube, J.F., Burnett, E.F.P(2005). Building Science for Building Enclosures, Building Science Press, Westford.
Tappuni, R. A.(1973). Generative Approach to the Thermal Design of Buildings in Hot Dry Climate, Unpublished Ph.D. thesis submitted to the University of Edinburgh.
Wasim Y, Saman & Khamis S. Gasim, (1984),Thermal Performance of Iraqi Building Construction, Proceeding of scientific Research Council- Baghdad, Research Center, Building Materials Department, Vol 2. Symposium Thermal Insulation of Hot-Dry Climate 26-28 Nov. 1984.
Dr.Akeel Noori AH is currently an Assist. Professor of the Architectural Engineering Department at the College of Engineering, University of Sharjah, UAE (2009~). He holds a PhD in Architecture & Environmental Impact Assessment (2004) from Faculty of Built Environment, Malaya University, Malaysia. He is a fully licensed consultant Architect since (1996). He has worked at Faculty of Architecture & Environmental Design, International University Malaysia 1998-2008, Guest lecturer in the Architectural Design Dept., University Putra Malaysia. He successfully combines professional and academic roles and has a particular interest in Heat Exchange in Building, EIA, Passive & Green Architecture. Dr. Akeel has been an active role in many important international environmental-related conferences such as the International Environmetrics Society, TIES 2005 Conference. He is also an author of number of papers and books; chapters in books, journal papers, and technical reports & has many papers presented in many international conferences as well. He has a distinguished professional experience and known by reputed international Architectural companies as a consultant, and designer on both public and private architectural projects in Malaysia, Iraq, Saudi Arabia and the UAE.
Peer Review: This article has been internationally peer-reviewed and accepted for publication
according to the guidelines given at the journal’s website.
*Corresponding author (Raed M. A. Elottol). Tel/Fax: +60174405868 . E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860 eISSN 1906-9642. Online Available at http://TuEngr.com/V02/265-285.pdf
265
International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
http://www.TuEngr.com, http://go.to/Research
A Practical Step towards Integrating Elderly Pathway Design into Museum Space Planning: Framework of Satisfaction Assessment Raed M. A. Elottol a* and Azizi Bahauddina
a School of Housing, Building and Planning, Universiti Sains Malaysia, MALAYSIA A R T I C L E I N F O
A B S T R A C T
Article history: Received 12 February 2011 Received in revised form 26 March 2011 Accepted 10 April 2011 Available online 01 May 2011 Keywords: Interior Environment, Museums’ Design, Pathway Design, Elderly, Satisfaction
The study examines how elderly visitors’ perception, interior environment, pathway design quality, and satisfaction are related in the context of interior environment and space planning of museums. This paper explores a theoretical as well as practical key issue in elderly pathway design in museums in Malaysia. The research intends to explore the elderly pathway design that interacts with the interior environment and space planning in museums. This is to fully understand the relationship between elderly visitors’ satisfaction and pathway design. This paper plans to answer critical questions; what is interior pathway design? How does the pathway design relate to the elderly visitors’ satisfaction? And what is the relationship between elderly visitors’ satisfaction, and pathway design quality? This study is one of the few studies focus on elderly people and pathway design. The empirical analysis carried out on 509 of elderly visitors in 21 museums in Malaysia allows us to confirm that the quality of interior pathway design is a direct determinant of elderly satisfaction. The results also reveal that there is a significant relationship between elderly satisfaction and quality perception. Finally, the interior environment elements of museums such as lighting design, furniture arrangement and finishes materials are also considered.
2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Some Rights Reserved.
1. Introduction This study concerns about the pathway design of the museums and the elderly visitors’
2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. 2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies.
266 Raed M. A. Elottol and Azizi Bahauddin
satisfaction in Malaysia, and to assess the adequacy of the circulation design of the museums,
the study uses the confirmation and disconfirmation process as a reference point to investigate
the overall satisfaction of the elderly visitors. Wener (2002) discusses the issues of
circulation, orientation and pathway design. According to him, there is growing evidence that
the interior designers of museums are either unconcerned or largely ignorant of the needs of
users and visitors. He considers pathway design in museums and orientation as the first, and
possibly the most basic behavioral need of visitors upon entering the museum. Wener also
highlights the nature of visitors in the museum and the questions of place orientation and
pathway, such as "where am I?" and "how do I get from here to there?" as well as the function of
pathway and circulation, such as "how does this pathway system work?". Elderly visitors in
museum will try to answer all these questions efficiently and fast to enjoy the visit and to spend
the rest of the time focusing on the objects in the museum (Weissmann. and Islam. 1996).
Richard (2002) states that if the pathway in buildings are insufficiently designed, the remaining
options for user will be asking others for help, observing the actions of others or spending much
time just to find the direction. He considers each option as a source of capriciousness and
therefore stressful in and of itself which may lead to dissatisfaction. The remaining option for
visitors is self-exploration, which can be even more frustrating (Wener, Richard et al. 1982;
Wener 2002). Weisman ( 1983) also finds in his study that experts' ratings of the complexity of
floor plans correlated highly with the likelihood of space users getting lost (Weisman 1983).
Reussner (2004) finds that, from the late 1980s, continuous criticism regarding to the lack of
studies and audience research for museums, as well as the lack of proper guidelines can
consider all genders and ages of visitors (Reussner 2004).
Until now there are no researches have been conducted to measure the attendance of
elderly people in museums, but some studies (Bitgood 1991; Weissmann. and Islam. 1996;
Rogers 1998; Tufts and Milne 1999; Rojas and Camarero 2008; Webb 2010) give indications
that elderly visitors are very interested in visiting museums. Based on Roger’s research (1998)
most of the museums visitors in his study are ranged from age 50 -70 (elderly), and as a result
of his study also, elderly visitors of museum have a high expectations concerning museums’
interior design and comfort level in terms of interior pathway and circulation system. Roger
explains that elderly attendance could be based on (a) personal characteristics such as nostalgia,
(b) experiences, and (c) general levels of satisfaction with the museum itself and interior design.
In different study Rojas and Camarero (2008) also state that in order to use museum resources
*Corresponding author (Raed M. A. Elottol). Tel/Fax: +60174405868 . E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860 eISSN 1906-9642. Online Available at http://TuEngr.com/V02/265-285.pdf
267
and design in the most successful and advantageous manner, museums need more studies to
identify what factors have to be considered for the visitors’ circulation and pathway in
museums (Rogers 1998; Rojas and Camarero 2008). Throughout museums’ basics, museum
design must emphasis the relationship between visitors and space. In Malaysia, the absence of
interior pathway design’s strategy for elderly visitors is noticeable, where at the museums in
Malaysia it is easy to get tired and old people may tire particularly quickly (Researcher 2009).
To achieve efficient interior circulation and pathway design of museums for elderly people,
designers must understand the nature of elderly visitors, behaviour, design data and their needs.
According to several studies (Wener 1998; Wavell, Baxter et al. 2002; Yin 2003) many of
the elderly visitors have impaired mobility, and some of them are in wheelchairs, but more
simply walk slowly and painfully. Some also use a stick or simply find stairs very difficult. In
order to overcome this problem, Malaysian government endorsed the Biwako Millennium
Framework for Action (BMF) in the year 2002. It announced the extension of the Asian and
Pacific Decade of Disabled and Elderly Persons (Meng 2009). Accessibility to built
environment and pathway design are some of the areas out of 7 priorities in the policy which
Biwako Millennium Framework for Action would like to achieve. The policy reflects the
consequence of implementing a barrier-free in order to accommodate the involvement of
disabled people and elderly in the society (Meng 2009). Thus Meng (2009) also states in his
study that, “The design strategy for pathway design and accessibility for elderly and disabled in
museums’ buildings in Malaysia needs to be ascertained” (Meng 2009). Mohamed and Mustafa
(2005) in their study also find that, designers are still unfamiliar with the needs of the elderly
people which are of great importance. They state that, In Malaysia, until now there is no source
or study which can give a great source of information related to the elderly user’s needs,
capabilities, and interior pathway design. However holding these sessions may be a challenge
for several reasons. These challenges involve adjusting for diversity of the older population and
their physical and cognitive differences, dealing with the attention characteristics of this
population (Black 2005; Black 2008).
Finally, several studies (Ching 2004; Department of Statistics in Malaysia 2009; Cusiima
2010; Department of Finance and Personnel 2010) highlight that understanding of museum
space planning and form of pathway is a very important factor affects the visitors’ circulation
and satisfaction with museums. So, it is believed that the desired outcomes of this study should
assist designers to consider better ways for museum space planning and pathway design by
268 Raed M. A. Elottol and Azizi Bahauddin
making them aware about the true level of elderly satisfaction with museums’ design in
Malaysia.
2. Interior Pathway and Circulation Design Bitgood (1988) highlights the importance of pathway design in museums. He states that,
the museums’ interior design and the layout of the exhibitions in the building that constrain
visitor circulation may determine visitors' methods of interaction with display objects (Bitgood
1994; Bitgood 2005; Bitgood 2010; Bitgood 2010). Therefore, the way in which pathway is
designed is the major question of museums’ interior design. Nowadays, It becomes a fact that
the interior pathway is the key issue for exhibition and museums’ design (Hall, Basarin et al.
2010; Haywood and Cairns 2010; Heath and Lehn 2010; Hendon 2010; Holjevac, Marković et
al. 2010; Holl’s 2010). At the same time designers must understand that all elements of
circulation and pathway are important, so in museum design process, pathway is the main key
of decisions regarding how the collection will be displayed and viewed for visitors. On the
whole, pathway design becomes critical for moving the museum’s visitors through the building
(The International Council of Museums 2009). Several studies state that interior design of
museums must meet the specific needs of elderly or disable visitors, such as accessibility,
pathway design quality, space planning, comfort level and visitors’ satisfaction (Foster 2010;
Goodman, Gallant et al. 2010; Goor-balk, Warmerdam et al. 2010; Hall, Basarin et al. 2010;
Haywood and Cairns 2010; John J. Koran, Jr. et al. 2010). So to design a museum properly the
interior pathway must be considered and involves the creation of solutions of all problems.
Therefore, elderly movement in space/time also to be resolved in the ultimate sustainable plan
(Yalowitz 2002; Yenawine 2002; Wunsch, Jones et al. 2010; Hsu 2004). Moreover, Hsu
(2004) and others highlight a very important issue that visitors may not be mindful of how their
bodies and movement are in continuous dialogue with the pathway and interior environment. In
different meaning, how visitors practice the three dimensionality of a building (perceptual
function) is mainly through movement of our bodies through time, sequence and space
(Zelanski and Fisher 2010; Zorloni and Wien 2010; Hsu 2004). Few researchers only wrote
about the pathway and the interior circulation within buildings. Beirne (2003) stresses that the
horizontal circulation and pathway can be considered as, “all walking areas on all floors of a
building required for physical access to some spaces”. This is including to the horizontal
features such as corridors, lobbies, verandas, porches, doors, entrance foyers, and balconies. He
also defines vertical circulation as; “all walking areas and mechanical tools installed in all
*Corresponding author (Raed M. A. Elottol). Tel/Fax: +60174405868 . E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860 eISSN 1906-9642. Online Available at http://TuEngr.com/V02/265-285.pdf
269
floors of a building required for vertical physical access to some space” This is also including to
staircases, ramps, elevators and escalators (Beirne 2003). Moreover, G. Black (2005) in his
research defines interior circulation in buildings as:
“The all walking areas on all floors of a building required for physical access to some subdivision of space, whether physically bounded by partitions or not. Included Horizontal and Vertical circulation, which should be but is not limited to, public corridors, exhibition spaces, entrance foyers, elevator lobbies, tunnels, bridges, and each floor's footprint of elevator shafts, escalators and stairways. Also included are corridors, whether walled or not, provided they are within the outside facelines of the buildings to the extent of the roof drop line.” (G. Black, 2005: 12).
Finally, Stephen (2009) explains clearly the interior circulation in the buildings as;
“A term describes how visitors make their way through the facility. What pathways do they take? Do visitors circulate the way the designers intended? Do visitors miss key exhibits because of the architectural design of the facility? Which direction do visitors turn when they reach choice points? Do visitors have a circulation strategy (e.g., "Turn right and follow the perimeter") or do they simply wander more or less aimlessly?” (Stephen, 2009: 44).
Ching (2004) discusses in detail the configuration of pathway design , he states that:
“All paths of movement, whether of people or services are linear in nature. And all paths have a starting point, from which we are taken through a sequence of spaces to our destination. The contour of path depends on our made of transportation. While we, as pedestrians, can turn, pause, stop, and rest at will” (Ching, 2004:134). In addition, Ching (2004) discusses the nature of a path’s configuration influences, the
factors affect path’s configuration. Ching thinks that the most important factor affects pathway
configuration is the visitors’ orientation within the building. According to Ching, there are
many types of circulation paths in buildings, Ching also lists down the most popular types such
as: Linear Circulation Path, Radial Circulation Path, Spiral Circulation Path, Grid Circulation
Path, Network Circulation Path and Composite Circulation Path (Ching 2004).
3. Elements of Interior Pathway Design and Circulations The efficiency of interior pathway and circulation system in museums determined by the
basic shape and form of building. Buildings of the same internal floor area and same function
differ in the proportion of space taken by elements of interior circulation and pathway. It differs
also in the design style of circulation and pathway elements such as lifts, corridors and other
mechanical equipment (Sookhanaphibarn and Thawonmas 2009.; Bitgood 2010; Bitgood 2010;
Bitgood 2010; Bolton 2010). The time needed by a visitor to move from one area within the
270 Raed M. A. Elottol and Azizi Bahauddin
building to another area and the enjoyment of doing this by visitors are affected by the building
form, pathway design and circulation style that is designed (Khan and Syed 2009;
Martı´n-Ruiz, Castellanos-Verdugo et al. 2009; Mattsson 2009; Meng 2009; Rohloff, Psarra et
al. 2009). The design of interior circulation elements such as stairs, corridors and mechanical
circulation elements are very important issue for interior designers. In addition, the design
quality of a building depends at first on the basic analysis of the traffic flow of visitors or users
and the follow-on decisions on the primary form of the building (Canada Science and
Technology Museum Corporation 2009; Carney 2009; Department of Statistics in Malaysia
2009; Foster, Koran et al. 2009; Guidlines 2009). In general, the elements of interior circulation
and pathway at a building such as lifts and escalators, stairs and corridors differ in visitors’
carrying capacity and design requirements. Moreover, the interior designers must consider and
match the characteristics of each element with those of the traffic generated in buildings
(Roberts, McKay et al. 2008; Rojas and Camarero 2008; Satoh 2008; Taha 2008; Tran 2008).
For example, the main entrance area in buildings is considered small but it is carrying a major
quantity of traffic, as become principal nodes of the pathway and circulation design, with the
optimum shape of the building dependent on the ratio between internal traffic and movement to
and from the outside (Abaci and Kamaraj 2009; Board of Directors of the Hawaii Public
Housing Authority 2009; British Standard 2009; Brititsh Standard 2009; Burns and Bowling
2009).
4. Aspects of Interior Pathway and Circulation Design Kaynar (2010) points out that, the designer must meets the pathway and circulation
function in buildings, and the architectural design should embrace appropriate space to house
and to improve traffic from area to area. Aspects of interior pathway determine the criteria for
the success of the design and evaluation criteria. According to Hsu (2004) this includes at least
five aspects: approach, entrance, configuration of the path, path/space relationship and form of
the circulation space. By using any museum as example, one can appreciate the relevance of
each following component of pathway and circulation (Amburg 2007; Banning and Schoen
2007; Brock 2007; Butterworth 2007; Rojas and Camarero 2007).
4.1 Approach The axial general view of the interior design and entrance lobby form the approach of the
interior circulation and pathway design in museums’ spaces. Based on the study of Kaynar
*Corresponding author (Raed M. A. Elottol). Tel/Fax: +60174405868 . E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860 eISSN 1906-9642. Online Available at http://TuEngr.com/V02/265-285.pdf
271
(2010) the distant view before entering the building is very important to prepare the visitors for
the experience of the spaces in the museums (Kaynar 2010; Hsu 2004).
4.2 Entrance The entrance of a museum is the start point where the visitors move from the outside space
to the interior space. Kaynar (2010) points out that Museum’s entrances are usually highlighted
by very visible items or attractive patterns, decorative or structural components. Finally, in
modern museums, great effects linked with the entrance design have served as a preview of
what the visitor can expect, which increase the expectation levels of visitors (Code 2003;
Communities 2003; Community Council of Devon 2006; Kaynar 2010).
4.3 Pathway Configuration Based on study of Kaynar (2010), he finds that pathway configuration is a term refers to
the path of movement from a starting point to the end point within the museum. In any building,
the configuration of the path is strong-minded by some conditions, such as the overall shape of
building, the form of the pathway, the volume of space selected to the path and organizational
pattern of the spaces it links. However, researchers (Pearlmutter, Berliner et al. 2006; Rounds
2006; Sakkas and Pe´rez 2006; Sharma and Dhariya 2006; Sheeks 2006) consider all paths as
linear, and the configuration or shape can take on other forms.
4.4 Path/Space Relationship According to several studies (Bitgood 1992; Bitgood 1999; Ching 2004; Black 2005;
Canadian Museums Association 2006; Community Council of Devon 2006; Foster 2010; John
J. Koran, Jr. et al. 2010) the relationship between the path and space in a museum can be linked
in three different ways. First, the path passes by the exhibitions and spaces, ensuring the
connectivity for each space. Second the path passes through spaces. In turn, the intervening of
spaces trespassed creates patterns of rest and movement. Third, the path terminates in a space,
often as a way of emphasizing the importance of the final destination. Kavangah (1991), in his
research highlights the importance of locations of facilities, and according to him, it is the time
now to consider the location of facilities in museums.
4.5 Form of the Circulation Space Form of the circulation, is how the pathways for movement are integrated into the spatial
organization of a building. So the form and size of the circulation space must to be considered
in museums. A circulation space may be enclosed, open on one side or open on both sides (Han
272 Raed M. A. Elottol and Azizi Bahauddin
and Cho 2006; J.A.Renshaw 2006; Jeong and Lee 2006; Jun, Kyle et al. 2006; Khattar 2006). It
also can be narrowed to encourage forward motion or widened to create spaces for waiting or
stopping. The form of the circulation space can be adjusted to distinguish the rote of the
pathway as either for visitors or service corridor (Community Council of Devon 2006; Crayford
2006; Dalke, Little et al. 2006; Davey 2006; Gutwill 2006). Ching (1979) discusses in detail the
configuration of path and the form of circulation space. According to him the form of pathway
depends on our design of transportation and building form. Several studies (Ching 2004;
Department of Statistics in Malaysia 2009; Cusiima 2010; Department of Finance and
Personnel 2010) highlight that understanding of museum space planning and form of pathway
is a very important factor which affects the visitors’ circulation and satisfaction with museums.
5. Elderly People and Satisfaction The definition of 'elderly' has differed among institutions and researchers. According to
Mat and Taha study (2003) The United Nations World Assembly On Ageing held in Vienna,
1982, used '60 years and over' as the cut-off in deliberating ageing trends (Mat and Taha 2003).
Immediately, Malaysian policy makers have adopted this demarcation and are officially used in
planning for senior citizens. This research has thus used the same age cut-off to refer to senior
citizens in Malaysia (Mat and Taha 2003; Wong, Rajikan et al. 2010). Recently, the populations
are growing older more and more in all countries all over the world. According to Kinsella &
Phillips (2005) by 2030, almost 1.2 billion of the expected 1.5 billion people age 65 or older
will inhabit in less developed regions and more will be in developed countries. The ratio of
aging 65-80 or older will reach to 14.3% while in Europe the ration will be 30% of all
populations which is very high. Therefore, just 22 % of the world’s older citizens will live in
developed countries (Kinsella and Phillips 2005). This demographic change will extremely
affect the health services, socioeconomic development, design requirements and sustainability
of all nations. The reason for that is the population aging may be seen as a human success story
of the country and a strong indication toward the strength of the level of public health, medical
advancements, and economic development over diseases. But the common phenomenon of
aging also brought an acknowledgement by the United Nations (UN) of the many challenges
such as, aging and design criteria, general development, issues concerning the sustainability
and the ability of states and communities to consider aging populations and to consider their
satisfaction (Kinsella and Phillips 2005). Figures 1 and 2 show population age-sex structure in
developed and less developed countries. A review of the population for the past four censuses
*Corresponding author (Raed M. A. Elottol). Tel/Fax: +60174405868 . E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860 eISSN 1906-9642. Online Available at http://TuEngr.com/V02/265-285.pdf
273
find a visible decreasing proportion of population in the younger ages and a sharp increase in
the older age groups (Kinsella and Phillips 2005).
Figure 1: Population age-sex structure in less developed countries, 1950, 1990, and 2030
(Kinsella and Phillips 2005).
Figure 2: Population age-sex structure in more developed countries, 1950, 1990, and 2030. (Kinsella and Phillips 2005).
It becomes a fact that the elderly people in Malaysia are increasing at a faster rate than the
total population growth and will more than double in numbers from the current 1.4 million to 5
million or more in 2030 (Mat and Taha 2003). Malaysia is considered as a fast developing
nation (Mat and Taha 2003), so recording the needs of elderly people is a crucial to balanced the
growth of the nation and to consider past, present and future trends of the elderly people in
Malaysia. According to Mat and Taha (2003) this is the time to create awareness of the space
planning and implementation of interior design for the elderly population in Malaysia (Mat and
Taha 2003). However, until now there are no studies measuring the level of elderly attendance
at museums in Malaysia. Researchers in Malaysia don’t know if elderly people are interested to
visit museums or not. Internationally, several studies (Gotlieb and Brown 1994; Korn 1994;
Parasuraman, Berry et al. 1994; Ritchie 1994; Katz 1994,) show that, elderly people are very
interested in visiting museums. In a study for a botanical garden museum, Hood and Roberts
274 Raed M. A. Elottol and Azizi Bahauddin
(1994) find that the group with the largest attendance was aged 55 and older. This group is
considered for one-third to one-half of the visitors on any given day. Studies find also that
elderly visitors were more interested in purchasing in the souvenir shops in museums (Gotlieb
and Brown 1994; Korn 1994; Parasuraman, Berry et al. 1994; Ritchie 1994; Katz 1994,).
6. Research Hypotheses According to Gronroos (2000) design quality can be defined from two perspectives. They
are technical quality (what is delivered to the visitors) and the functional service quality (how it
is delivered) (Rojas and Camarero 2007; Pile 2010). In another study, Brady and Cronin (2001)
figure out that the design quality can be outlined by three perspectives. They are outcome
quality, interaction quality, and physical environment quality in buildings. As the environment
quality refers to the ambient conditions(Rojas and Camarero 2007). Oliver (1997) states that
visitors’ interpretation is related to the level of expectations. According to (Rojas and Camarero
2007) expectations is known as previous predictions or beliefs of visitors before they enter the
building. According to Oliver (1997), the quality of design is based on perceptions of
excellence. Oliver (1997) also states that it is logical to believe that perceived quality is
influenced by the expectations of the visitors (Rojas and Camarero 2007). It becomes a fact that
visitors use their expectations to evaluate design quality and performance. Therefore,
researchers propose the first hypothesis:
(H1. Visitors’ expectations positively influence visitors’ perception of interior pathway
design quality and interior environment of museums.)
Recently, design quality is believed to be the right judgment exposed by visitors who
estimating the quality level of design. So, satisfaction and design quality are highly interrelated
(Rojas and Camarero 2007). Researchers accept the theory said that quality leads to
satisfaction. On this basis, we propose the second hypothesis:
(H2. Interior Pathway design and space planning of museums positively influence the
elderly visitors’ satisfaction.)
Disconfirmation happens when interior pathway design quality is lower or higher than
what visitors expected after they made the final decisions (Oliver 1996). If the interior designs
higher or lower that the visitors’ expectations, a positive or negative disconfirmation occurs and
this will increase or decrease the level of satisfaction. According to Oliver (1996):
*Corresponding author (Raed M. A. Elottol). Tel/Fax: +60174405868 . E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860 eISSN 1906-9642. Online Available at http://TuEngr.com/V02/265-285.pdf
275
“Consumer satisfaction is a function of expectations and disconfirmation, and prior expectations are used as the comparable standard. Past empirical research has shown that expectations have a significant effect on disconfirmation”(Oliver 1996; Rojas and Camarero 2007).
7. Methodology In order to test the proposed hypotheses, the empirical study performed is based on
information collected by means of a questionnaire presented to visitors of 21 selected museums.
The 21 Museums are located in Kuala Lumpur, Terengganu, Selangor and Kedah in Malaysia.
The museums have been selected based on the following criteria: (a) State history theme, (b)
Geographic location, (c) Annual attendance, and (d) Quality of interior design & environment.
After proceeding to the quantitative study of 21 museums, interviews and observations
(qualitative study) conducted for four selected museums. The four museums have been selected
based on the following criteria; the importance and the value of the museum, number of visitors
per year, style of design, and location of museum (Figure 1).
Figure 1: Locations of selected museums in Malaysia.
Interviews with the museums’ managers, employees and visitors were performed in order
to know visitors’ reactions and emotions during their visits. A questionnaire was developed to
test the aforementioned hypotheses. The questionnaire was divided into two parts. The first part
covered the experience, mood and the expectations before the visit. The second part referred to
the design quality, the disconfirmation of expectations, the pleasure and the satisfaction after
the visit. The first survey was conducted during the months of July to October 2009 and the
total number of questionnaires distributed was 800. A second set of data was collected through
observations and interviews during October, and November 2009, providing valid data for
analysis. Those surveyed were asked to answer the first part of the questionnaire, (i.e. the
questions referring to their experience, mood and expectations). After answering these
276 Raed M. A. Elottol and Azizi Bahauddin
questions, the visitor held onto the questionnaire during the visit, and the second part of the
questionnaire was completed upon exit. Of these 800 questionnaires, 613 were returned. One
hundred and four questionnaires were excluded (40 incomplete and 64 the age of participants
were under 65 years old). The total numbers of questionnaires analysed were 509
questionnaires with observed response rate of 76.6%. Analysis was conducted using the
statistical software package SPSS version 17.0 with a sample size of 509, α (the probability of
making a correct retention is 0.95) =0.05, df (degree of freedom) = 1.0. Of the 509 respondents,
290 were men (57.4%) and 215 were women (42.6%). Three hundred and forty eight visitors
(69.3%) were 65-70 years old, one hundred and forty eight visitors (29.7%) were equal or more
71 to 90 years old. Of the 509 respondents, 271 (53.9%) were locals, and 229 (45.5%)
foreigners. Of the locals, 162 were Malay (32.2%), 61 were Chinese (12.1%), 76 were Indian
(15.1%), indicating that Malay visitors are more interested in visiting museums than others.
Of the 509 Participants, only 43 (8.5%) of elderly visitors came alone to the museum, while 212
(42.1 %) came with friends and 185 (36.7%) came with their families. The rest of participants
60 (11.9%) visited museums with organizations. The scale of expectations is constructed of
five items were adapted from the scale proposed by (Rojas and Camarero 2007) and also was
applied to the case of museums and exhibition centres. The scale of perceived quality (six
items) was prepared from the proposal of Brady and Cronin (2001). All of the included items
of expectations were adapted to reflect the context of interior pathway and circulation in
museums. The results of the responses (either agree or disagree) were presented under the
check-list of three categories obtained from literature review; a) horizontal pathway &
circulation design, b) vertical pathway & circulation design, and c) Interior environment and
space planning. In horizontal pathway item, the results of the responses (either agree or
disagree) were presented under the check-list of six factors based on the literature review such
as; horizontal accessibility, halls’ arrangement and spaces, corridors and entrance lobbies,
waiting areas, orientation system, furniture arrangement and interior layout. In vertical
pathway design, the results of the responses (either agree or disagree) were presented under the
check-list of three factors based on the literature review such as; vertical accessibility, position,
visibility and capacity of lifts, ramps and staircases, and interior paths and circulation. In
interior environment item, the results of the responses (either agree or disagree) are presented
under the check-list of four factors based on the literature review such as; creativity and interior
environment, interior materials and textures, interior lights and interior colours. To measure
satisfaction (five items) the Oliver (1996) scale was used and included additional items that
*Corresponding author (Raed M. A. Elottol). Tel/Fax: +60174405868 . E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860 eISSN 1906-9642. Online Available at http://TuEngr.com/V02/265-285.pdf
277
measured the intention to repeat the visit and word-of-mouth recommendation. All scales were
validated the values of reliability were calculated by the Cronbach alpha in each case. The
data in this study have been obtained in three ways: (a) personal observations (qualitative study
without a formal survey) on the museums of the study areas, (c) personal oral interviews with
the elderly visitors in the study areas, and (c) a survey (quantitative study) of the study area
using questionnaires. All the qualitative factors of the circulation and pathway design in the
museums are adopted from the previous studies. The answer for satisfactory is "Yes", but when
it is unsatisfactory, the answer is "No".
8. Analysis and Results The first hypothesis (H1) states that there will be significant relationship between elderly
visitors’ expectation in museum, and design quality perception. The correlation coefficient is
-.083- . As the result suggests, a significant negative relationship does not exist ( Sig= 0.061);
therefore, this can be concluded from these result, that elderly visitors' expectation before they
entering the museum don’t determine or affect the elderly visitors’ perception of the design
quality of the interior pathway and circulation in museums. The second hypothesis (H2) stated
that the interior pathway design and space planning of museums positively influence the elderly
visitors’ satisfaction. From the result the correlation coefficient is 0.685 . Sig (2-tailed) or P
value is 0.000 ≤ α 0.05 which can be concluded from these result that there is a positive
significant relationship between elderly visitors’ satisfaction in museum and interior pathway
and circulation design, thus H2 is confirmed that the interior pathway design and space
planning of museums positively affect the level of the elderly satisfaction. Results also state
that there will be a positive significant relationship between elderly visitors’ satisfaction, and
time spent within museums. The correlation coefficient is 0.404. As the result, a significant
relationship exists; therefore, this can be concluded from these result, that time spent within the
museum influenced by elderly visitors' satisfaction , thus time spent within museums consider
as a good an indicator of satisfaction. In other words, satisfied visitors tend to spend more time
walking in museums. As illustrated in table 1, a whole, it is overwhelmingly clear that in all of
the factors under all the different categories, the respondents have until today a far greater
negative perception towards interior pathway and circulation design of museums in Malaysia.
Such negatively weak perception of the pathway and circulation design towards museums in
Malaysia is an expression of their dissatisfaction level in the nature of the circulation designs of
these museums. Finally, in the three categories, the respondents have scored 41.03 % < 50% for
278 Raed M. A. Elottol and Azizi Bahauddin
qualitative and 43.26 % < 50% for quantitative analysis, suggesting a clear feeling of
dissatisfaction towards the interior pathway and circulation design and the interior
environments of the selected museums. Table 1, presents a combination of the results of the
analyses via a qualitative method with those results obtained via a quantitative method. An
integrative examination of the composite data via a combination of methods (in this case
quantitative and quantitative procedures) in this way is termed as "triangulation" in this study.
Researchers subject data to such a triangulation procedure because such procedure helps
counteract threats to validity.
Table 1: Overall composite averages in all categories.
Categories of Factors Selected 21 Museums
"Satisfactory" scores from Qualitative survey
( )
"Satisfactory" scores from Quantitative survey
Interior Pathway Design 41.725 % 44.225 % Interior Environment and Space Planning 39.66 % 41.33 %
Overall composite average 41.03 % 43.26 %
9. Discussion and Conclusions This study began with the aim of analyzing a specific aspect of interior design and space
planning applied to museums in Malaysia, and the formation of visitors’ satisfaction. The first
implication of this research is the confirmation of hypotheses due to its high validity and
explanatory power. In particular, the respondents selected from the museums in Malaysia
have a high level of expectation towards the interior pathway, circulation design and interior
environment in museums. Such positively strong expectation is undoubtedly an expression of
their level of experience and trust towards the design industry in Malaysia. Moreover, the
Interior pathway and circulation design quality appears to be multidimensional consisting of
different three dimensions. The Three dimensions are horizontal pathway design, vertical
pathway design, and interior environment of museums. Under each dimension there are many
different components. The scores from the survey have demonstrated overwhelmingly same
low perceptions and bad expression about the interior pathway design and interior environment
in museums in Malaysia. These negative design qualities of the circulation design in museums
together with the positive and high expectations of the elderly visitors compositely justify the
low level of general satisfaction of the elderly visitors in museums. This being the case, the
dissatisfaction seems to have arisen from :The absence of design creativity, the absence or
*Corresponding author (Raed M. A. Elottol). Tel/Fax: +60174405868 . E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860 eISSN 1906-9642. Online Available at http://TuEngr.com/V02/265-285.pdf
279
disregard the elderly needs, the insufficient accessibility to interior halls and other spaces, the
inflexibility of the halls arrangement and use of the spaces, the lack of waiting areas and
comfort seats, the use of poor or inappropriate interior materials and textures, the insufficient
design of corridors and pathway design, the insufficient design of orientation system within the
museums, the use of poor or inappropriate interior position and design of staircases ramps and
lifts, the insufficient design of interior lighting system, the use of poor or inappropriate interior
colours, insufficient furniture arrangement and interior layout, interior pathway and
circulations in general are not suitable for elderly visitors. The ideas that interior pathway
design and interior environment must be good, as a high percentage of the elderly visitors find it
useful and can enhance their satisfaction level. Yet, little thought seems to have been given to
what interior pathway is, what is necessary to achieve visitors' circulation efficiency, and what
benefits can be expected. Interior designers in Malaysia have not considered effectively the
interior pathway design of elderly visitors. Elderly visitors learn more and are to be more
satisfied when they are properly circulated and oriented to an exhibition and when the
exhibition is designed with an understanding of their needs and abilities.
This will require us to re-think again about interior pathway and circulation design quality
of museums in Malaysia. This study has several limitations, as some of the them are: 1) First
study - this is the first study of its type and additional research is needed to confirm the results,
2) The results were mixed and full support wasn't obtained for all factors, 3) Unit of Analysis
-While it is appeared that the notion of interior circulation design was universal regardless of
industry or size, this research limited itself to the study of interior circulation quality at
museums environment in Malaysia, 4) Lack of prior relevant research, 5) Generalizing the
findings of this study - Due to geographical limitations, participants may possess certain
attributes that differ from those in other parts of the world.
Future research may use more diversified random samples to verify the dimensions
developed in this study. Interior pathway design could be the trend in museums and visitors'
studies in the future, so more studies of this nature should be carried out. However, the interior
designers are invited to continue this initial investigation of interior pathway design quality
within museums, especially in new areas of design where we knew our user elderly preferences,
needs and abilities. Interior circulation elements are a design strategy, a success value and
quality indicator of museums design. It is the communication and circulation tools, strategy and
280 Raed M. A. Elottol and Azizi Bahauddin
technology that permit the combination of all museums' services and visitors.
10. Acknowledgment A very special thank you is due to Dr.Siriporn Kobnithikulwong for insightful comments,
helping clarify and improve the manuscript.
11. References Abaci, O., & Kamaraj, I. (2009). Museums as an educational medium: an implementation
model. Procedia Social and Behavioral Sciences, 1 (1), 1337-1341.
Amburg, D. V. (2007). Why Customer Satisfaction Matters in the Public Sector. Digital Citizen, 12(8), 2-35.
Banning, S. A., & Schoen, M. (2007). Maximizing public relations with the organization–public relationship scale: Measuring a public’s perception of an art museum. Public Relations Review, 33 (1), 437–439.
Beirne, S. (2003). Suzie Beirne m.d.i.a. Usenature (Usenature.com).
Bitgood, S. (1991). Suggested Guidelines for Designing Interactive Exhibits. Journal of Visitor Vehavior Vol. VI(No. 4), 111-121.
Bitgood, S. (1992). Visitor Orientation and Circulation: Some General Principles. Jacksonville State University, Volume VII(Number 3), 15-30.
Bitgood, S. (1994). Designing Effective Exhibits: Criteria for Success, Exhibit Design Approaches, and Research Stategies. Journal of visitor Behavior, Volume IX(Number 4), 4-19.
Bitgood, S. (2005). An Analysis of Visitor Circulation: Movement Patterns and the General Value Principle. Jacksonville State University, Jacksonville, AL
Bitgood, S. (2010a). An Analysis of Visitor Circulation: Movement Patterns and the General Value Princip. Jacksonville State University, 16(8), 256-264.
Bitgood, S. (2010b). Problems in Visitor Orientation and Circulation. Jacksonville State University, 14(7), 155-170.
Bitgood, S. (2010c). The Role of Attention in Designing Effective Interpretive labels. Journal of Interpretation Research, 5(2), 31-45.
Bitgood, S. C. (1999). Impact of setting factors on visitors. Visitor Studies, Volume II(Issue 2).
Black, G. (2005). Engaging Museum ( Developing Museums for Visitors Involvement) (6th Edition ed. Vol. 2). New York: Routledge.
Black, J. (2008). Museum Application Design for Older User.
Board of Directors of the Hawaii Public Housing Authority. (2009). Designated Housing For Elderly And Disabled Families. Hawaii Public Housing Authority, 1-5.
*Corresponding author (Raed M. A. Elottol). Tel/Fax: +60174405868 . E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860 eISSN 1906-9642. Online Available at http://TuEngr.com/V02/265-285.pdf
281
Bolton, S. (2010). The Task Force on Museums and First Peoples, a Decade Later: A Case Study of the McCord Museum of Canadian History. 22-32.
British Standard. (2009). Corridors, Lobbies And Paths.Unpublished manuscript.
Brititsh Standard. (2009). Horizontal Circulation.Unpublished manuscript.
Brock. (2007). Pedestrian Circulation. Brock University Campus Plan.
Burns, G., & Bowling, N. (2009). Dispositional Approach to Customer Satisfaction and Behavior. Springer Science and Business Media, 9(1), 99–107.
Butterworth, M. (2007). Railway Museum (Advancing Railway Preservation). Journal of the Association of Railway Museums, 45(1), 2-20.
Canada Science and Technology Museum Corporation. (2009). Corporate Plan Summary Unpublished manuscript.
Canadian Museums Association. (2006). Museums For Tomorrow. Canada Routledge.
Carney, J. (2009). An initiative for a new index and opinion survey to measure satisfaction amongst customers of the commercial property industry. RICS, 12(2), 46-50.
Ching, F. D. K. (2004). Architecture: Form. Space & Order (Vol. 3). New York: Van Nostrand Reinhold Company.
Code, C. D. (2003). Access, Egress, and Circulation.Unpublished manuscript, City of St. Helens - Community Development Code.
Communities, T. W. G. o. M. a. S. (2003). Museums and Sustainable Communities.Unpublished manuscript.
Community Council of Devon. (2006). Access & Awareness Project 2005-2008, A&A Information Sheet 9 (CORRIDORS & CIRCULATION).Unpublished manuscript.
Crayford, M. (2006). Navigating The Museum. Australian National Maritime Museum, 13(2), 303-309.
Cusiima. (2010). Circulation- Specific Plan.Unpublished manuscript.
Dalke, H., Little, J., Niemann, E., Camgoz, N., Steadman, G., Hill, S. (2006). Colour and lighting in hospital design. Journal of Optics and Laser Technology 38(1), 343–365.
Davey, G. (2006). An Hourly Variation in Zoo Visitor Interest: Measurement and Significance for Animal Welfare Research. Journal Of Applied Animal Welfare Science, 9(3), 249–256.
Department of Finance and Personnel. (2010). Building Regulations Part R - Access To And Use Of Buildings.Unpublished manuscript.
Department of Statistics in Malaysia. (2009). Socio-Economic Characteristics Of The Elderly In Malaysia.Unpublished manuscript.
Foster, D. (2010). Measuring Customer Satisfaction In The Tourism Industry. Paper presented at the Third International & Sixth National Research Conference on Quality Management.
282 Raed M. A. Elottol and Azizi Bahauddin
Foster, J., Koran, J., MaryKoran, Stark, S., Blackwood, A., & Landers, H. (2009). The Effect of Multispecies Exhibits on Visitor Attention at The Jacksonville Zoological Park.Unpublished manuscript, Gainesville, Florida.
Goodman, L., Gallant, G., Brown, J., & Miller, S. (2010). Design Consideration in Developing Alternative Housing. Government of Canada and the City of Toronto., 21(2), 2-29.
Goor-balk, A. v., Warmerdam, L., Ghameshlou, Z., & Masurel, E. (2010). satisfacation among Museum Visitors: The Holistic Approach Confirmed Empirical Evidence from the Anne Frank House Visitors. Cultural Economics, 43(7), 14-30.
Gotlieb, & Brown. (1994). Consumer Satisfaction And Precieved Quality. Journal of Applied Psychology, 79(6), 875-885.
Guidlines, D. (2009). Circulation Areas.Unpublished manuscript.
Gutwill, J. P. (2006). Labels for Open-ended Exhibits: Using Questions and Suggestions to Motivate Physical Activity. Visitor Studies Today, Volume 9(Issue 1).
Hall, J., Basarin, V. J., & Lockstone-Binney, L. (2010). An empirical analysis of attendance at a commemorative event: Anzac Day at Gallipoli. International Journal of Hospitality Management, 29 (1), 245–253.
Han, S.-J., & Cho, S.-B. (2006). Predicting User’s Movement with a Combination of Self-Organizing Map and Markov Model. Springer-Verlag Berlin Heidelberg, 2(4), 884–893.
Haywood, N., & Cairns, P. (2010). Engagement with an Interactive Museum Exhibit. UCL Interaction Centre, London WCIE 7DP, UK, 12(2), 113-129.
Heath, C., & Lehn, D. v. (2010). Interaction and Interactives. King's College London, 7(2), 13-37.
Hendon, R. C. (2010). Arts Participation: Comparing The Elderly and Non-Elderly. 83-83.
Holjevac, I. A., Marković, S., & Raspor, S. (2010). Customer Satisfaction Measurement In Hotel Industry: Content Analysis Study. University of Rijeka, 12(1), 31-40.
Holl’s, S. (2010). Lighting Up The Midwest. Museum, Kansas City, Usa, 14(9), 41-50.
Hsu, L. ( 2004). Circulation in Museums. 2(3), 122-150
J.A.Renshaw. (2006). Getting a Measure of Satisfaction from Eye Tracking in Practice. School of Computing Leeds Metropolitan University, UK, 14(6), 78-81.
Jeong, J.-H., & Lee, K.-H. (2006). The physical environment in museums and its effects on visitors’ satisfaction. Building and Environment, 41 (1), 963–969.
John J. Koran, Jr., M. L. K., & Foster, J. S. (2010). The (potential) Contributions of Cognitive psychology to visitor studies. The University of Florida, Gainesville.
Jun, J., Kyle, G., & O’Leary, J. T. (2006). Perceived Constraints To Art Museum Attendance. Northeastern Recreation Research Symposium, 14(2), 459-466.
Katz, P. (1994,). A Quantitative And Qualitative Analysis Of Natural Daylighting In Modern And Pre-Modern Architecture: Let There Be Light . University of
*Corresponding author (Raed M. A. Elottol). Tel/Fax: +60174405868 . E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860 eISSN 1906-9642. Online Available at http://TuEngr.com/V02/265-285.pdf
283
Wisconsin-Milwaukee, 3(3), 86-100.
Kaynar, I. (2010). Visibility, movement paths and preferences in open plan museums: An observational and descriptive study of the Ann Arbor Hands-on Museum. Journal of University of Michigan, II(5), 150-162.
Khan, & Syed, S. (2009). Risk Factors For Depression; Findings Of A Descriptive Study Conducted In Penang, Malaysia. Journal of Clinical and Diagnostic Research, 3(6), 1859-1866.
Khattar, V. (2006). QoS and Customer Satisfaction: A Study. Pipeline 3(2), 56-60.
Kinsella, K., & Phillips, D. R. (2005). Global Aging: The Challenge of Success. A publication of the Population Reference Bureau, Vol. 60, (1), 201-244.
Korn, R. (1994). Studying Your Visitors: Where To Begin. History News, 49(2), 23-29.
Martı´n-Ruiz, D., Castellanos-Verdugo, M., & Oviedo-Garcıa, M. d. l. A. (2009). A visitors’ evaluation index for a visit to an archaeological site. Tourism Management, xxx(1), 1–7.
Mat, R., & Taha, H. M. (2003). Socio-Economic Characteristics of The Elderly In Malaysia. Paper presented at the 21st Population Census Conference 19 – 21 November 2003
Mattsson, J. (2009). Listening to customers in face-to-face service encounters. Department of Communication, Business and Information Technologies - Roskilde University, 5(2), 3-25.
Meng. (2009). Built Heritage vs Accessibility. Retrieved 09-02-2009: http://www.pmh83.blogspot.com
Oliver. (1996). A Behavioral Perspective on the Consumer (1st Edition ed. Vol. 2). Boston, Mass.: Irwin- Me Graw-Hill.
Parasuraman, Berry, & Zeithaml, V. A. (1994). Reassessment of Expectations as a Comparison Standard in Measuring Service Quality. Journal of Marketing, vol. 58, no, 1, pp 111-124.
Pearlmutter, D., Berliner, P., & Shaviv, E. (2006). Physical modeling of pedestrian energy exchange within the urban canopy. Building and Environment, 41 (1), 783–795.
Pile, J. F. (2010). Interior Design (3rd Edition ed. Vol. 1). London Sage Inc.
Sites' invistigations and museums' observations (2009).
Reussner, E. M. (2004). Best Practices in Audience Research and Evaluation Case Studies of Australian and New Zealand Museums. Volume VII Issue II Visitor Studies Today.
Ritchie, I. (1994). Bonn: Museum Of Contemporary Art- East Meets West Ian Ritchie Statements About Adapted Historical Architecture. Ian Ritchie, 2(2), 92-98.
Roberts, D. C., McKay, M. P., & Shaffer, A. (2008). Increasing Rates of Emergency Department Visits for Elderly Patients in the United States, 1993 to 2003. Annals of Emergency Medicine, 51(6), 769-774.
Rogers, M. L. (1998). An exploration of factors affecting customer satisfaction with selected
284 Raed M. A. Elottol and Azizi Bahauddin
history museum stores.. Texas Tech University, Texas
Rohloff, I. K., Psarra, S., & Wineman, J. (2009). Experiencing Museum Gallery Layouts through Local and Global Visibility Properties in Morphology (An inquiry on the YCBA, the MoMA and the HMA). the 7th International Space Syntax Symposium, 7(2), 94-108.
Rojas, C. d., & Camarero, C. (2008). Visitors’ experience, mood and satisfaction in a heritage context: Evidence from an interpretation center. Tourism Management, 29(1), 525–537.
Rounds, J. (2006). Doing Identity Work in Museums. Curator: The Museum Journal, 49(2), 133-150.
Sakkas, N., & Pe´rez, J. (2006). Elaborating metrics for the accessibility of buildings. Computers, Environment and Urban Systems, 30 (1), 661–685.
Satoh, I. (2008). Context-Aware Agents to Guide Visitors in Museums. National Institute of Informatics, 12(2), 441–455.
Sharma, K., & Dhariya, T. D. (2006). Towards an inclusive, barrier free and right based society. empowerpoor, 2(4), 1-16.
Sheeks, A. (2006). Fort Worth Museum of Modern Art (Tadao Ando).
Sookhanaphibarn, K., & Thawonmas, R. (2009.). A Movement Data Analysis and Synthesis Tool for Museum Visitors’ Behaviors. Springer-Verlag Berlin Heidelberg, 3(1), 44–154.
Taha, D. D. A. H. (2008). Museums In Malaysia: Challenges And Development.Unpublished manuscript, Kuala Lumpur.
The International Council of Museums. (2009). Definition of Terms. Retrieved 15 October, 2010, from http://icom.museum/statutes.html#2
Tran, L. U. (2008). The professionalization of educators in science museums and centers. Journal of Science Communication, 7(4), 211-226.
Tufts, S., & Milne, S. (1999). Museums: A Supply-Side Perspective. Annals of Tourism Research, 26(3), 613-631.
Wavell, C., Baxter, G., Johnson, I., & Williams, D. (2002). Impact Evaluation Of Museums, Archives And Libraries: Available Evidence Project: The Robert Gordon University.
Webb, R. C. (2010). Comparing High-Involved and Low-Involved Visitors: A Review of the Consumer Behavior Literature. Suffolk University, Boston, Massachusetts
Weisman, G. (1983). Way Finding and Architectural Legibility: Design Considerations in Housing for the Elderly," in Housing for the Elderly: Satisfaction and Preferences. U. Regnier and J. Pynoos, eds. New York: Garland Press.
Weissmann., A. J., & Islam., R. (1996). Traffic circulation study and long-range plan Texas Department of Transportation Research and Technology Transfer 17(1), 109-236.
Wener, Richard, & Robert Kaminoff. (1982). "Improving Environmental Infor¬mation: Effects of Signs on Perceived Crowding and Behavior," Environment and Behavior 14, no. 6: 671-94.
*Corresponding author (Raed M. A. Elottol). Tel/Fax: +60174405868 . E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860 eISSN 1906-9642. Online Available at http://TuEngr.com/V02/265-285.pdf
285
Wener, R. E. (1998). The Environmental Psychology of Service Encounters. Environmental Psychology '103.
Wener, R. E. (2002). The Environmental Psychology of Service Encounters. The Service Encounter.
Wong, S. H., Rajikan, R., Das, S., Yusoff, N. A. M., Lee, L. K., Aziz., S. A. (2010). Antioxidant Intake and Mild Cognitive Impairment Among Elderly People in Klang Valley: A Pilot Study. Journal of Sains Malaysiana, 4(39), 689–696.
Wunsch, H., Jones, A. T., & Scales, D. C. (2010). Intensive Care for the Elderly: Current and Future Concerns. 935-943.
Yalowitz, S. S. (2002). Personality and Motivation in Visitor Satisfaction. journal of visitor studies today, 4(3), 214-217.
Yenawine, P. (2002). Interactive Learning in Museums of Art and Design ‘Notes on Aesthetic Understanding and Its Development’. Visual Understanding in Education, New York, 12(3), 23-28.
Yin, R. K. (2003). Case Study- Research Design And Methods (3rd Edition ed. Vol. 2). California: Sage Publication.
Zelanski, P., & Fisher, M. P. (2010). Design Principles And Problem S. Awareness Of Design 23(2), 3-31.
Zorloni, A., & Wien, K. (2010). Achieving excellence: Investigation into the use of performance indicator in museums. IULM University, I(5), 230-245.
Dr.AZIZI BAHAUDDIN is currently Associate Professor in Interior Design at the School of Housing, Building & Planning, Universiti Sains Malaysia. His main research areas are focusing on Exhibition Design/Interior Design; Art and Design especially researching on Cultural Issues and Ethnography, and in Architectural and Cultural Heritage in Tourism.
RAED M. A. Elottol is currently a PhD candidate in Interior Design at the School of Housing, Building & Planning, Universiti Sains Malaysia. His main research areas are focusing on Museums; Space Planning/Interior Design; Architecture especially researching on Cultural Issues and Building Technology.
Peer Review: This article has been internationally peer-reviewed and accepted for publication
according to the guidelines given at the journal’s website.
:: International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
http://TuEngr.com
Call-for-Papers:
ITJEMAST invites you to submit high quality papers for full peer-review and possible publication in areas pertaining to our scope including engineering, science, management and technology, especially interdisciplinary/cross-disciplinary/multidisciplinary subjects.
Next article continue on next page
*Corresponding author (Bangaly KABA). Tel/Fax: +225 21 30 34 57 Ext. 111 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/287-301.pdf
287
International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
http://www.TuEngr.com, http://go.to/Research
Validating Measurements of Perceived Ease Comprehension and Ease of Navigation of an Online Learning Technology: Improving Web Based Learning Tool Adoption and Use Bangaly KABAa*
a Schools of Business, International Relations and Economic Policy (BIREP), International University of Grand-Bassam, IVORY COAST A R T I C L E I N F O
A B S T RA C T
Article history: Received 21 March 2011 Received in revised form 27 May 2011 Accepted 31 May 2011 Available online 01 June 2011 Keywords: Technology; Acceptance; Model; WebCT (Web course tools); Measurement; E-learning.
Many universities are realizing that the implementation and use of online learning tool become a competitive advantage to address the actual learning needs. The purpose of this study is to determine the factors that influence users’ perceived ease of use of Webct an online learning tool. We administrated a questionnaire to undergraduate students from an university in Quebec, Canada. The results tend to corroborate that ease of comprehension and ease of navigation are the key factors which influence the perceived ease of use of WebCT. More specifically, the terms used in educational web applications must be as simple and relevant as possible. Jargon and technical terms in the wording of text used for links should be carefully avoided. This research is extending the finding of IT adoption studies by specifying what make an online tool easy to use.
2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Some Rights Reserved.
1. Introduction Recently, following the example of other organizations, a large number of universities
have been giving primary importance to the use of information and communication
technologies (ICTs), allocating substantial resources to their acquisition. ICTs are used on a
2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies.
288 Bangaly KABA
daily basis in universities to build students and employees’ databases, to carry out statistical
analyses, to conduct refined bibliographical research, to send e-mails, to permit multimedia
animation in classrooms, etc. (Bradley et al., 2006; Mbarika et al., 2003a, 2003b). In addition to
these uses, ICTs have become the preferred media for distance learning services (Mbarika,
2004), thus considerably reducing temporal and spatial constraints (geographical disparities).
The current trend is for distance learning to become an option for a great number of instructors
to respond to the new needs of students.
The investments made in order to acquire, implement and use ICT for educational purposes
should be expected to result in positive impacts for the quality of instruction. More specifically,
these investments should materialize in the form of increased productivity, a reduction in
transaction costs, and therefore; in improved performance (Goodhue et al. 2000; Mathieson,
1991).
Many models have allowed researchers to determine and measure the factors involved in
the adoption of a technological innovation (Goodhue et al., 2000; Mathieson, 1991; Taylor and
Todd, 1995). Among these, Davis (1989)’s technology acceptance model (TAM) figures as a
classic in the field of the adoption of technological innovations. TAM is generally referred to as
the most influential and commonly employed theoretical model in information systems
research (Lee et al. 2003). This theory is of particular interest in explaining user behavior with
regard to IT. TAM has been consistently validated by a number of empirical studies (Davis et
al., 1989; Kwon and Chidambaram, 2000; Mathieson, 1991; Taylor and Todd, 1995; Venkatesh
et al., 2003).
However, since most of these studies aim to test the model, opportunities for the
information systems and information technology (IS/IT) community to contribute become
more and more restricted if serious theoretical modifications are not made to the fundamental
model. At least two possible criticisms of TAM can be made. First, TAM is a generalized
theory which does not always seem to take into account particular types of technological
innovations. In fact, the process of acceptance depends upon the nature of the IT (Igbaria, 1994;
Mahler and Rogers 2000; Markus, 1997). Secondly, TAM fails to provide useful explanations
which could help those who design or manufacture IT to increase the level of acceptance of
their products by end users (Venkatesh and Davis, 2000, Benbasat and Barki, 2007).
*Corresponding author (Bangaly KABA). Tel/Fax: +225 21 30 34 57 Ext. 111 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/287-301.pdf
289
This situation considerably limits the practical application of TAM (Benbasat and Barki,
2007). In light of this finding, we intend in this study to validate new scales of measurement of
the ease of use of WebCT, which is a course management system for online learning.
This study based on technology acceptance model (TAM) is initiated to validate the
measurement of the factor that influence users’ perceived ease of use of WebcT in order to
enhance our understanding of online learning tools use. TAM stated that easier is to use a
system or a technology high is the probability of its adoption and use. Unfortunately, the model
does not indicate what make practically a technology easy to use. Our main research question
is: what are the practical factors or measures which could be considered as alternative of users’
perceived ease of use? We consider that perceived ease of comprehension and perceived ease of
navigation as good alternatives which could serve as measurements of the ease of use of
WebCT even other online learning tools. Before outlining the conceptual framework of this
study, we consider it is useful to present the characteristics and the attractions of WebCT which
may be unfamiliar to the general public.
2. Overview of WebCT Among internet and Web-based applications for online courseware, WebCT emerges as a
leader (Clark, 2002). This application was designed by the information systems department of
the University of British Columbia about a decade ago. Since then, the functionality of WebCT
has constantly improved, and it is now used by more than 2,200 institutions in more than 70
countries (WebCT, 2005). WebCT is a powerful tool for the creation of a distance learning
environment. It provides a complete set of tools for the delivery of an online course (Palloff
and Pratt, 2001 ; Mioduser et al. 2000). Once instructors and students become familiar with the
software, it can be used for e-learning. WebCT offers the possibility of synchronous and
asynchronous communication, sending e-mails, file sharing, student evaluations, access to
course materials, and access to outside resources dedicated to learning.
3. Theoretical Framework Chris et al. (2004) emphasize the importance of the online knowledge management tool’s
user interface as a critical factor for its adoption and for online learning. Indeed, as a link
290 Bangaly KABA
between the user and the system, the user interface allows a reduction of effort by making the
navigation among the different components of the system easier.
The success of an online application also relies upon the terminology used. The
terminology of a system refers to all words, phrases, and abbreviations it uses (Lindgaard,
1994). For example, a frequent problem with online courseware systems has to do with the
technical jargon used. This jargon includes technical or professional vocabularies with which
general users are often unfamiliar. In such cases, great effort must be made by end users in order
to utilize the system to its full potential. A clear and comprehensible terminology can thus
reduce the effort necessary to master the system and to make users more productive.
Consequently, it may be concluded that clarity of terminology is a good measurement of
perceived ease of use.
Davis et al. (1989) states that a technology or a system designed in such a way as to allow
its potential user to expend little time or energy (avoiding the constant need to refer to the user’s
manual or to contact the provider for help, etc.) will encounter few obstacles to its adoption.
These authors predict that the more a technology is perceived to be easy to use, the greater the
likelihood of its adoption. According to Davis et al. (1989), ease of use corresponds to the
degree to which a person believes that using a new IT will be easy. It is measured by the
following three indicators using Likert scales: the technology is easy to master, the technology
is user-friendly, the technology, in general, is easy to use. These measurements are for general
purposes and do not always appear to take into account the specific characteristics of a given
type of technology. This lack of specificity is susceptible to make the task of IS designers more
arduous when it comes time to determine the specific aspects of the system which could
influence users’ perceptions.
The previous shortcoming has led Moore and Benbasat (1991) to argue that one of the
problems facing the theories related to the adoption of technological innovations is the lack of
valid, trustworthy instruments to measure users’ perceptions in the context of adoption of these
innovations. Our intent in the current study is to identify and validate measurements of the
perception of ease of use which takes into account the features of a specific technological
innovation, which is WebCT.
The concept of ease of use is generally used in the literature on user acceptance of
*Corresponding author (Bangaly KABA). Tel/Fax: +225 21 30 34 57 Ext. 111 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/287-301.pdf
291
technology and on user behavior. As previously mentioned, Davis et al. (1989) identify ease of
use as one of the important determinants of the use of ICTs. Davis (1989) suggests that the
perceived ease of use can in fact determine the perceived usefulness. Mathieson (1991) and
Szajna (1996) report that ease of use accounts in large part for variations in perceived
usefulness. Therefore, in light of the aforementioned contributions, we can assert that a better
comprehension of the measurements of ease of use of WebCT constitutes a worthwhile domain
to investigate, because it could have a beneficial effect on the other determinants of ICT
success.
Inspired by the study of Lederer et al. (2000), we propose in the current research, the ease
of comprehension and the ease of navigation as alternative measurements of WebCT’s ease of
use. However, unlike Lederer et al. (2000), we consider that these two variables are rather
measurements of perceived ease of use, not the antecedents.
After having pinpointed the various theoretical contributions that are relevant to our
analysis, the next section focuses on the methodology adopted in this research.
4. Methodology
4.1 Questionnaire Development The data for this study was collected through a questionnaire survey that was divided into
different sections. Each section was devoted to each variable of the research model: Task
characteristics, group characteristics, facilitating conditions, social influence, and the intention
of the users. A seven-point Likert scale, where 1 indicates “strongly disagree” and 7 “strongly
agree” (see questionnaire in appendix) was used to measure the latent variables used in the
study, with the exception of socio-demographic factors. These latent variables included:
perceived ease of use, perceived ease of comprehension, perceived ease of navigation,
perceived competency, computer anxiety, technical support and user help, and experience using
the internet. Variables measurements were inspired by Lederer et al. (2000) and Davis et al.
(1989), and adapted to the context of this study. Each variable’s was measured using multiple
items. Aside from demographic factors, the present analysis is only concerned with two
variables, “perceived ease of use” and “ease of navigation”. In the following section we
present the results obtained by our analysis.
292 Bangaly KABA
A pre-test of the questionnaire was performed in order to assure its content validity before
its final distribution to the respondents. First, we designed a preliminary version of the
questionnaire. This version was given to researchers in the field of IT and information systems
(IS), and to experts in the industry familiar with the African context. Each individual provided
some comments on the formulation, the syntax, and the number of items included in the
questionnaire. Taking into account the various comments, we made minor changes to the
questionnaire. The various comments also permitted us to eliminate biases which could exist in
the questionnaire. .
4.2 Data Collection
Data in this study were collected using a questionnaire survey. Orlikowski and Baroudi
(1991) maintain that the questionnaire survey is the method of data collection mostly used in IT
research. This method is often indicated for gathering data, describing and explaining people’s
perceptions, attitudes, or behaviors. Questionnaires have the advantage of being structured and
assuring standardization in the formulation of questions and in their sequence. We administered
a survey to undergraduate students at a French-speaking university in Canada that use WebCT
in their course of studies. It should be noted that in this university, WebCT served as an
instructional supportive tool.
In order to be assured of a high response rate, we administered the survey by direct contact.
This mode of communication is very demanding in terms of investment, both in the time it takes
and in the amount of travel required. However, it seems to be the richest data collection
technique (Emory, 1980). With the instructors’ assistance, we solicited students’ direct
participation in their classrooms. The questionnaires were filled out on a voluntary basis before
the beginning of courses. We obtained 172 usable responses out of 230 questionnaires
administered, yielding a 75% response rate.
4.3 Data Analysis
The statistical analysis for this study employed the SPSS statistical software. The
assessment of the collected data’s descriptive statistics, construct validity and the testing of the
indicators’ reliabilities were conducted in SPSS. The factor analysis of principal component
was mainly applied to validate the measurement of easy of comprehension and easy of
navigation.
*Corresponding author (Bangaly KABA). Tel/Fax: +225 21 30 34 57 Ext. 111 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/287-301.pdf
293
5. Results Details of the socio-demographic variables chosen for this study are given in Table 1.
Table 1: Socio-demographic profiles.
Variables Characteristics Absolute Frequencies
Percentage
Gender Male Female
57 115
33.1% 66.9%
Age 16 - 21 years 22 - 27 years 28 - 33 years 34 - 39 years 40 or older
67 87 10 6 2
39% 50.6% 5.8% 3.6% 1.2%
Years of experience using the internet
Less than 1 year 1 year 1 to 2 years 2 to 3 years 3 to 4 years 4 to 5 years 5 or more years
1 1 7
15 27 33 88
0.6% 0.6% 4.1% 8.7%
15.7% 19.2% 51.2%
Different uses of the internet
Information seeking Downloading Sending email Chat Forum
6.32 5.10 6.61 3.29 2.92
1.04 1.84 0.93 2.16 1.87
The socio-demographic variables examined in this study are concerned with gender, age,
years of experience using the internet, and the uses made of the internet. Only a third of the 172
respondents were men. The predominance of women in university programs is a reality which
cannot be ignored. The respondents were relatively young, since 154 of the respondents
(89.6%) are less than 30 years old. According to Paré (2002), the new generation of students has
an unprecedented level of mastery of ICTs (computers and the Internet). It is interesting, but not
surprising in the North American context, that the vast majority of respondents seem to be
familiar with the use of the internet. Indeed, 70.4% of respondents possess more than four
years’ experience using the internet, which could favor their acceptance of WebCT which is a
web-based application.
However, the respondents show a very weak score in terms of their use of the online chat
and of discussion forum. This low score is a bad sign of WebCT usage as these functionalities
are nonetheless among the essential components of the application, since they permit both
synchronous and asynchronous communication among learners as well as with the instructor.
294 Bangaly KABA
5.1 Validation of the scales of measurement used Variables measurements were validated through convergent and discriminant validity
testing. A principal components factorial analysis (PCA) was performed on each variables
measurement items in order to verify both types of validity. Additionally, the reliability of
each variable measurement was established by calculating Cronbach’s Alpha coefficient. The
tests of convergent and discriminant validity and of reliability are three measures necessary for
the validation of a scale of measurement. In the following section, the results of these three tests
are presented.
5.1.1. Test of convergent validity
An analysis of the correlations among the items measuring each variable was first carried
out, followed by a principal components analysis (PCA) with Varimax rotation when more than
one factorial axis was found.
The use of this method must satisfy three criteria. The first one is the criterion relative to
the eigenvalue which aids in identifying the number of components (factors) to retain. In this
study, we refer to Kaiser (1958)’s rule according to which only the axes whose eigenvalue is
higher than 1 are retained. The second criteria is related to the factorial contributions (loadings)
which aims at identifying relevant items or indicators that better explain a factor. According to
this criterion, only items with factorial contributions greater than 0.3 are accepted (Blau et al.,
1993). The last criterion deals with the communalities of items and it indicates the proportion of
explained variance in the combination of each factor. This criterion allows the assessment of
the level of representation of each item in the principal components. In this study, an item
whose communality was inferior to 0.4 was dropped from the analysis, in compliance with the
suggestions of Evrard et al. (2003).
5.1.1. Measurement of Perceived Ease of Comprehension
Table 2 includes items measuring the ease of comprehension. Results in Table 3 show
that the correlations among the items of measuring the ease of comprehension are positive and
*Corresponding author (Bangaly KABA). Tel/Fax: +225 21 30 34 57 Ext. 111 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/287-301.pdf
295
significant, which might be a manifestation of the uniqueness of this measurement. The PCA
yields a factor which explains 68.36% of the total variance, with important positive factorial
contributions (loadings) and a good quality of representation for each item (>0.4) (see Table 4).
Based on the above results, we can state that the unidimensionality of this measurement has
been proven.
Table 2: Presentation of items measuring the ease of comprehension. Variable Codification Items description
Ease of comprehension
3.1 WebCT uses relevant terms
3.2 WebCT uses simple terms
3.3 WebCT includes links that give detailed information
3.4 WebCT has a pleasant design
3.5 WebCT posts pages that are easy to read
Table 3: Correlations matrix of ease of comprehension. Items 3.1 3.2 3.3 3.4 3.5 3.1 3.2 3.3 3.4 3.5
1 0.753** 0.646** 0.486** 0.587**
1
0.555** 0.490** 0.589**
1 0.573** 0.608**
1 0.750**
1 *** p< 0.01; ** p<0.05; *p<0.1 ns: not significant
Table 4: Factorial solution of ease of comprehension. Variables (Ease of
comprehension) Quality of representation Items
3.1 3.2 3.3 3.4 3.5
0.842 0.820 0.818 0.795 0.857
0.709 0.673 0.668 0.633 0.734
Eigenvalue 3.418 Explained variation 68.356
5.1.1 Measurement of perceived ease of navigation Table 5 shows items measuring the ease of navigation. The correlations among the items
of the perceived ease of navigation variable are all positive and significant (Table 6) and
296 Bangaly KABA
demonstrate the uniqueness of measurement of this variable. The PCA results in Table 7 show a
unique factor explaining 79.65% of the variance. All the items have a very good quality of
representation (>0.4).
Table 5: Presentation Items measuring the ease of navigation Variable Codification Items description
Ease of Navigation
4.1 WebCT allows me to easily return to previously-viewed pages
4.2 I can always tell where I am when navigating WebCT
4.3 WebCT is an easy site to navigate
Table 6: Correlations matrix of ease of navigation Items 4.1 4.2 4.3
4.1 4.2 4.3
1 0.715** 0.647**
1
0.721**
1 *** p< 0,01; ** p<0,05; *p<0,1 ns: not significant
Table 7: Factorial solution of ease of navigation Variables (Perceived ease of navigation) Quality of representation
Items 4.1 4..2 4.3
0.881 0.912 0.884
0.776 0.832 0.781
Eigenvalue 2.389 Explained variation 79.649%
5.1.2 Discriminant Validity The objective of this test is to verify the independence of the variables. Like for the test of
convergent validity, a principal components analysis was carried out on the items measuring
each variable. Three items were dropped from the analyses because each of them had a loading
greater than 0.3 on the two selected factors. These items are: Item 3.3 (WebCT includes links
that give detailed information) and item 3.4 (WebCT has a pleasant and agreeable design) for
the variable ease of comprehension; and item 4.3 (WebCT is an easy site to navigate) for ease of
navigation. According to the results discussed above and shown in table 8, we can assume the
independence of the two variables of the research.
*Corresponding author (Bangaly KABA). Tel/Fax: +225 21 30 34 57 Ext. 111 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/287-301.pdf
297
The reliability test will conclude this validation of scales. The results appear in the
following table:
Table 8: Results of the test of discriminant validity Variables Ease of
comprehension Ease of
navigation Items 3.1 3.2 3.5 4.1 4.2
0.887 0.872 0.809
0.924 0.884
Eigenvalue 2.894 1.139 Explained variation 57.888% 22.783%
5.1.3 Analysis of the Reliability of the Measurement In order to ascertain the degree to which the measurement instrument (the questionnaire)
used in this study evaluates the perceptions of respondents in a consistent manner, we
performed a reliability analysis by calculating Cronbach’s Alpha coefficient. The results for the
two constructs of the study appear in the Table 9.
Table 9: Results of the reliability test.
Variables of the study Variables Items Cronbach’s Alpha
Wording Ease of comprehension 3.1.; 3.2; 3.5 0.8367 Ease of navigation 4.1; 4.2 0.8315
Throughout these results, we notice that the value of Cronbach’s Alpha for all the variables
is superior to 0.7, which shows the reliability of the adopted measurement instrument (Evrard et
al., 2003 ; Teo et al., 1999).
6. Conclusion, Limits, and Directions for Future Research The goal of the present study was to determine and validate measurements of the
perception of ease of use which takes into account the features of an online tool, which is
298 Bangaly KABA
WebCT. According to the analysis carried out in this work, perceived ease of comprehension
and perceived ease of navigation emerge as good alternatives which could serve as
measurements of the ease of use of WebCT, and indeed of other online interaction and learning
tools.
The implications of these results, for the designers of Web-based educational applications
in general and for those of WebCT in particular, are to continue to work toward making their
product as user-friendly as possible. More specifically, the terms used in educational web
applications must be as simple and relevant as possible. Jargon and technical terms in the
wording of text used for links should be carefully avoided. These recommendations are equally
valid for the academic content on WebCT. The results of this study can also be of benefit to
those individuals responsible for selecting online applications, in that they would know in
advance the relevant factors to take into account in order to increase the likelihood of success of
the chosen technologies.
Nevertheless, this research has its limits. For a better assessment of the face validity or the
content validity of the measurement used, it would have been helpful to recruit experts to
examine them. Increasing the survey sample size would also have been quite useful to ensure
that the study’s findings could be generalized. In the future, this study could be extended to
include other departments or universities where the level of ICT use is heterogeneous in order
to evaluate and understand possible differences in results. Further, the extension of the research
to other countries where the level of students’ access to e-learning tools is limited or at least is
still at an embryonic stage would constitute a relevant basis for comparison of the external
validity of the measurement instrument validated by this study. In such a study, it would be
beneficial to proceed with a confirmatory factor analysis.
*Corresponding author (Bangaly KABA). Tel/Fax: +225 21 30 34 57 Ext. 111 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/287-301.pdf
299
7. Acknowledgment A very special thank you is due to Associate Professor Dr. Boonsap Witchayangkoon for
insightful comments, helping clarify and improve the manuscript.
8. References Blau, G., A. Paul and N. St. John. (1993). “On developing a general index of work
commitment,” Journal of vocational behavior, Vol. 42, no. 3, pp. 298-314.
Benbasat, I. and Barki, H. 2007. Quo vadis, TAM? Journal for the Association of Information Systems, Vol. 8, no.4, pp. 211-218
Bradley, R., Sankar, C., Clayton, H., Raju, PK, and Mbarika, V. (2006). “An Empirical Investigation of the Impact of GPA on Perceived Improvement of Higher-Order Cognitive Skills,” Decision Sciences Journal of Innovative Education.
Chris, Evans A, Nicola J. G. B., Kavita S. B, Darren K. G. (2004). “Virtual learning in the biological sciences: pitfalls of simply ‘‘putting notes on the web”,” Computers & education, Vol. 43, pp. 49–61.
Clark, J. (2002). “A product review of WebCT,” Internet and Higher education, Vol. 5, p. 79–82
Davis, F. D. (1989). “Perceived usefulness, perceived ease of use, and user acceptance of information technology,” MIS quarterly, Vol.13, no. 3, pp.318-343.
Davis, F. D., R. Bagozzi P. and P. R. Warshaw. (1989). “User acceptance of computer technology: a comparaison of two theoretical models,” Management science, Vol. 35, no. 8, pp. 982-1003.
Emory, C. W. (1980). Business research methods. Revised edition, Homewood Irwin Inc.
Evrard, Y., B. Pras and E. Roux. (2003). Market: études et recherches en marketing. 3rd edition, Paris, Dunod.
Goodhue, D. L., B. D., Klein and S. T., March. (2000). “User evaluation of IS as surrogates for objective performance,” Information & management, Vol. 38, pp. 87-101.
Igbaria, M. (1994). “An examination of the factors contributing to microcomputer technology acceptance,” Accounting, management and information technology, Vol. 4, no.4, pp. 205-224.
Kaiser, H.F (1958). “The varimax criterion for analytic rotation in factor analysis,” Psychometrika, Vol. 23, p. 187-200.
http://www.itcortex.com/Stat_Failure_Cause.htm (visited 20 December 2003)
300 Bangaly KABA
Lindgaard, G. (1994). Usability testing and system evaluation: A guide for designing useful computer systems, Chapman & Hall, London.
Lederer, D.; Maupin, D.; Sena, M. and Zhuang, Y. (2000). “The technology acceptance model and world wide web,” Decision support systems, Vol. 29, no. 3, p. 269-282.
Lee, Y., Kozar, K.A., Larsen, K.R.T. (2003). The Technology Acceptance model: Past, Present, and future. CAIS, Vol. 12, pp. 752-780.
Legris, P. , J., Ingham and P. Collerette. (2003). “Why do people use information technology? A Critical review of the technology acceptance model,” Information & management, Vol. 40, pp. 191-204.
Mahler, A. and Rogers M. Everett. (2000). “The diffusion of interactive communication innovations and the critical mass : the adoption of telecommunication services by German banks,”.Telecommunication policy, Vol. 23, pp. 719-740
Markus, M. L. (1987). “Toward a critical mass theory of interactive media: universal access, interdependence and diffusion,” Communication research, Vol. 14, pp. 491-511.
Mathieson, K. (1991). “Predicting user intentions: comparing the Technology Acceptance Model with the Theory of Planned Behavior,” Information systems research, Vol. 2, no. 3, pp.173-191.
Mbarika, V., Sankar, C.S., Raju, P.K. (2003a). “Role of Multimedia Instructional Materials on Multicriteria Technology and Engineering Decisions,” Decision Sciences Journal of Innovative Education, Vol. 1, #2.
Mbarika, V., Sankar, C.S., Raju, P.K. (2003b). ”Identification of Factors that Lead to Perceived Learning Improvements for Female Students,” IEEE Transactions on Education, Vol. 46, # 1, pp. 26-36.
Mbarika, V. (2004). “TeleEducation in Sub-Saharan Africa: A Breakout Approach to Sub-Saharan Africa’s Education Dilemma,” IEEE Technology and Society,Vol. 22, #4, pp. 20-26.
Mioduser, D.; Nachmis, R.; Lahave, O.; Oren, A. (2000). “Web-based learning environments: current pedagogical and technological state,” Journal of research on computing in education, Vol. 33, no. 1, pp. 55-76.
Moore, G. C. and Benbasat, I. (1991). “Development of an instrument to measure the perception of adopting an information technology innovation,” Information systems research, Vol.2 no.3, pp. 37-46.
Mustonen-Ollila, E. and K. Lyytien. (2003). “Why organizations adopt information system process innovations: a longitudinal study using diffusion of innovation theory,” Information systems journal, Vol. 13, p. 275-297.
Orlikowski, W.J. and J. J. Baroudi, (1991). “Studying information technology in organizations:
*Corresponding author (Bangaly KABA). Tel/Fax: +225 21 30 34 57 Ext. 111 E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/287-301.pdf
301
research approaches and assumptions,” Information systems research, Vol. 2, no. 2, pp. 1-28.
Palloff, R., and Lamaster, K. (2001). “Lessons from the cyberspace classroom,” The realities of online teaching, Sans Francisco: Jossey-Bass.
Paré, G. (2002). “La génération Internet : un nouveau profile d’employé,” Gestion, Vol. 27, no. 2, pp.47-57.
Szajna, B. (1996). “Empirical evaluation of the revised technology acceptance model,” Management science, Vol. 42, no. 1, pp. 85-92.
Taylor, S and Todd, P.A. (1995). “Understanding information technology usage: a test of competing models,” Information systems research, Vol. 6, no. 2, p. 91-108.
Teo, T.; Lim, V. and Lai, R. (1999). “Intrinsic and extrinsic motivation in Internet usage,” Omega, International Journal of Management Science, Vol. 27, no. 1, pp. 25-37.
Venkatesh, V. and F. D. Davis (2000). “A theoretical extension of the technology acceptance model: four longitudinal field studies,” Management science, Vol. 46, no. 2, p. 186-204.
WebCT (2005). http://WebCT.com/entrypage, visited September 2007
Dr. Bangaly Kaba earned his PhD degree in Information Systems from a joint PhD program administered by the four largest universities in Montreal (UQAM, HEC, Concordia University and McGill University). He is a visiting professor at International university of Grand-Bassam. His research interests include the adoption and implementation of information and communication technologies (ICT), especially mobile technologies, the impact of ICT on organizations, cultural issues in ICT adoption and use, tele-education, multimedia learning case study, quantitative methods, and management of international projects.
Peer Review: This article has been internationally peer-reviewed and accepted for publication
according to the guidelines given at the journal’s website.
:: International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
http://TuEngr.com
Call-for-Papers:
ITJEMAST invites you to submit high quality papers for full peer-review and possible publication in areas pertaining to our scope including engineering, science, management and technology, especially interdisciplinary/cross-disciplinary/multidisciplinary subjects.
Next article continue on next page
*Corresponding author (David Kuria). Tel: +254-727-399208. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/303-324.pdf
303
International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
http://www.TuEngr.com, http://go.to/Research
A Land Data Assimilation System Utilizing Low Frequency Passive Microwave Remote Sensing: A Case Study of the Tibetan Plateau David Kuriaa*, Toshio Koike b, Moses Gachari a, and Souhail Boussetta b, c a Department of Geomatic Engineering and Geospatial Information Science, Kimathi University College of Technology, KENYA b River and Environmental Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, The University of Tokyo, JAPAN c Currently at: European Centre for Medium-Range Weather Forecasts, UNITED KINGDOM A R T I C L E I N F O
A B S T RA C T
Article history: Received 15 March 2011 Received in revised form 2 June 2011 Accepted 3 June 2011 Available online 6 June 2011 Keywords: Soil moisture retrieval, Land Surface Modelling, Data assimilation, Passive microwaves, AMSR-E, Tibetan Plateau, Surface emission model
To address the gap in bridging global and smaller modelling scales, downscaling approaches have been reported as an appropriate solution. Downscaling on its own is not wholly adequate in the quest to produce local phenomena, and in this paper we use a physical downscaling method combined with data assimilation strategies, to obtain physically consistent land surface condition prediction. Using data assimilation strategies, it has been demonstrated that by minimizing a cost function, a solution utilizing imperfect models and observation data including observation errors is feasible. We demonstrate that by assimilating lower frequency passive microwave brightness temperature data using a validated theoretical radiative transfer model, we can obtain very good predictions that agree well with observed conditions.
2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Some Rights Reserved.
1. Introduction While General Circulation Models (GCMs) are best at simulating evolving and future
changes in climate systems, they are unable to produce mesoscale and local atmospheric
2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies.
304 David Kuria, Toshio Koike, Moses Gachari, and Souhail Boussetta
phenomena (Wilks, 1999). Thus downscaling methods are necessary to bridge the gap between
global scales and other smaller modelling scales. In this paper we use a high resolution
mesoscale model and nest it within a GCM. This nesting is realized by using initial and
boundary conditions from GCM output. This approach alone is not adequate for reproducing
local phenomena and extreme events because nesting does not include accurate land surface
initial and boundary conditions, missing important physical processes such as convection and
local circulation (Boussetta, 2005).
Many satellite based microwave imaging systems have been launched in space. Some of
the recent ones include the Scanning Multichannel Microwave Radiometer (SMMR) launched
in 1978 and Special Sensor Microwave Imager (SSM/I) launched in 1987. More recent sensors
launched include Advanced Microwave Scanning Radiometer on board Earth Observing
Satellite (AMSRE) and Tropical Rainfall Monitoring Mission (TRMM). These systems
provide observations of variables that describe the earth’s atmosphere, ocean, cryosphere and
land surface (Njoku, 1999). To aid in the interpretation of imagery from such sensors,
microwave radiative transfer models have been developed, which are used to express
propagation of microwaves in media, such as in Ulaby et al. (1981), Tsang et al. (1985), and
Wilheit et al. (1999).
Data assimilation employs models and observations exploiting the strengths of each.
Models are approximations of physical processes, and these approximations introduce errors
due to varying degrees of inaccuracy in representing these processes. On the other hand,
observations while recording actual situations include random observations errors. In addition,
due to costs incurred in obtaining these observations, they are more often than not inadequate,
and are not uniformly distributed in time and space. Thus, models or observations on their own
are not adequate in representing actual physical systems being studied or monitored. By
applying data assimilation approaches, these limitations in model representation and in
obtaining observations can be offset.
Data assimilation techniques have evolved within meteorology and physical oceanography
and in operational numerical weather prediction for atmospheric and oceanic flows (Ide et al.,
1997). These concepts have recently been applied to small scales, but this has largely been in
attempts to improve estimation of soil moisture by assimilation of microwave TBs (Mahadevan
*Corresponding author (David Kuria). Tel: +254-727-399208. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/303-324.pdf
305
et al., 2003, 2007; Reichle et al., 2001). In mesoscale modelling, it is critical to provide reliable
initial and boundary conditions. GCM forecast and analysis products can provide such data, but
these have to be downscaled to the mesoscale before they can be used. By combining
downscaling and data assimilation techniques, better initial conditions can be obtained, which
can thereafter be used to run the mesoscale model, giving better forecasts. Sensitivity of L-X
microwave bands to surface conditions has been exploited in the past in retrieving soil moisture
conditions (Njoku, 1999). Since at these frequencies the atmosphere can be assumed
transparent, clarification of surface emission heterogeneity through field experiment has a
potential of supporting a retrieval scheme for land surface conditions.
By exploiting data assimilation approaches and using a physically based surface emission
model as observation operator, there is potential to obtain better land surface condition
prediction by assimilating lower frequency microwave brightness temperatures. To physically
address the mechanisms of land-atmosphere interactions based on land surface conditions, the
Land Data Assimilation System developed by Boussetta (2005) is used to augment the
stand-alone mesoscale model. While this system addresses land surface heterogeneities, it does
not address atmospheric components in a direct way. This is not critical since this research is
restricted to using lower frequency brightness temperatures in the data assimilation exercise.
This system assimilates lower frequency (6.925 – 18.7 GHz) microwave TBs to improve
estimation of land surface conditions. In this paper we build on the work done by Boussetta
(2005), by including as observation operator an improved surface emission model that was
validated by Kuria et al. (2007).
Data assimilation is a method of estimating a set of parameters by optimizing the fit
between the solution and a set of observations which the model is meant to predict (Bannister,
2001). In this context, the procedure of adjusting the model parameters until the model ‘best
predicts’ the observables is referred to as optimization. The observations used for data
assimilation can be very heterogeneous with respect to their temporal and spatial resolution,
and their type. The results of an assimilation scheme are a continuous data set, which represents
the best estimate for the state of the system. This is done by optimizing the state vector of the
system using available observations and dynamic constraint of the numerical model, specified
by the governing dynamical equations.
306 David Kuria, Toshio Koike, Moses Gachari, and Souhail Boussetta
In variational data assimilation not only is a a close fit to one observation (the last one)
required but additionally, consistency with a dynamic model over a defined period of time
(Daley, 1991). This means that in variational data assimilation, one tries to adjust the model
globally to fit all observations during the assimilation period.
A discrete model for the evolution of an atmospheric, coupled system from time ti to time ti+1 is
governed by the equation
(1)
where x and M are the model’s state vector and its corresponding dynamics (model) operator,
respectively. The state vector x has dimension n. M represents the model simulation or
prediction, and may differ from equation (1) if the model is nonlinear and/or deterministic. The
state vector x describes the state variables.
Observations y0 at time ti are defined by
(2)
where H is an observation operator, and ε is noise or observation errors. The observation vector
has dimension pi. A major problem of data assimilation is that, typically, .
The observation operator H, can be nonlinear, like M, and both can contain explicit time
dependence - denoted by subscript i - in addition to the implicit dependence via the state vector
. The error ε is assumed to have a normal distribution with mean 0. Its covariance
matrix is denoted by R, consisting of instrumental and observation errors.
In variational data assimilation one tries to adjust the model’s initial parameters x0,
globally to all observations available during the assimilation period. Therefore it is necessary to
introduce a scalar quantity J, which represents the difference between the model and observed
states. The objective function is a function of the state vector x. J is the sum of the background
error JB, which gives the difference between the model state and the background xb and an
observation error J0, which gives the difference between the model state and observations The
complete cost function can be written as;
*Corresponding author (David Kuria). Tel: +254-727-399208. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/303-324.pdf
307
(3)
The common form of JB is expressed as
(4)
where, x0 is the analysis variable, or state vector, is the background field, and B is the
background error covariance matrix.
The common form of J0 is given as
12
, (5)
where, y0 represents all of the satellite observations, H is the observation operator, M is the
model operator, and R is the observational error covariance matrix. In this paper, y0 represents
remotely sensed microwave brightness temperatures, and H is a radiative transfer model, which
computes corresponding brightness temperatures. N is the length of an assimilation window.
Thus, relatively accurate observations are used directly to correct model-estimated values, and
these corrections are fed back in the solution process.
The total cost function can be rewritten in as follows:
12
(6)
Various assumptions have been made when formulating the above cost function. The first
assumption is that the models are ‘perfect’ over the assimilation period, which leads to the
308 David Kuria, Toshio Koike, Moses Gachari, and Souhail Boussetta
so-called strong-constraint formalism. An alternative cost function could be written with a third
term, as an additional constraint to penalize model errors. This would be an example of a weak
constraint formalism (Mahadevan et al., 2007). Due to its compactness, we adopt this
strong-constraint approach in this paper.
2. Meso scale model run Figure 1 shows the Tibet Coordinated Enhance Observing Period (CEOP) site. The Tibetan
plateau is located in Asia with an area of approximately 3000 × 1000 km2 and a mean elevation
of more than 4 km above mean sea level.
(a) (b)
Figure 1: CEOP Tibet Site: (a) Satellite imagery, with red pegs marking the extents
corresponding to AMSR-E image. Marked with small yellow pegs are 4 in-situ stations. This
image was obtained from Google Earth. (b) Terrain map generated by ARPS.
It is bounded by the highest mountains in the world (Himalayas, Kunlun shan, Pamir). It is
considered an important component of the global water and energy cycle as it exerts
appreciable thermal and dynamic influences on the local and regional meteorology as well as on
the Northern Hemisphere atmospheric circulations (Yang et al., 2009).
*Corresponding author (David Kuria). Tel: +254-727-399208. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/303-324.pdf
309
Table 1: Model domain specifications.
Variable Description Setting
Δx East West spacing 5560 m (0.05°)
Δy North South spacing 5643 m (0.05°)
λm Central longitude 91.9°E
φm Central latitude 32.0°N
nx East West grids 70
ny North South grids 70
nz Vertical levels 41
While there are other mesoscale models such as the Weather Research and Forecasting
(WRF) model and the Fifth-Generation Penn State Mesoscale Model (MM5), the Advanced
Regional Prediction System (ARPS) developed at the Center for Analysis and Prediction of
Storms (CAPS) (Xue et al., 2003) as the mesoscale model for simulating surface and
atmospheric evolution of Tibetan Plateau conditions. ARPS was used since a coupling of this
model had been done with Simple Biosphere Model (SiB2) and had demonstrated good results
in simulating land surface conditions (Boussetta, 2005). Table 1 defines the domain settings of
Tibet area used in the simulation and validation exercise. This area is about 390 × 390 km2
providing ample overlap over an AMSR-E brightness image covering an area of about 280 ×
280 km2 with central position defined as (32°N, 91.9°E). The z- dimension is staggered with
higher resolution provided near surface (30 m) and smoothly transitioning to lower resolution at
higher elevations (1.2 km). This is to significantly improve simulation of near surface features
which vary rapidly over time. The simulation were undertaken to simulate three days evolution
of land and atmosphere condition. This period was from 19th August 2004 00:00 UTC – 22nd
August 2004 00:00 UTC. The integration time steps were as follows: (i) evolution of surface
condition (120 seconds) (ii) small time step (1 second) and (iii) big time step (6 seconds).
2.1 Initial and Boundary conditions For this paper, we used National Centers for Environmental Prediction (NCEP) Global
Forecast System (GFS) reanalysis data to provide initial and boundary conditions for running
the Mesoscale model. The GFS is a global spectral data assimilation and forecast system. GFS
forecasts are produced every 6 hour. The output product has a horizontal resolution of 1° and
310 David Kuria, Toshio Koike, Moses Gachari, and Souhail Boussetta
vertically it has 64 layers with model top layer at 0.2 hPa.
We used the EXT2ARPS package to generate the required lateral boundary forcing,
linearly interpolated in time to the domain of our model run. This GFS generated boundary
conditions were updated every 6 hours. The package ARPSTRN generated terrain data from
30”× 30” global topographic dataset provided by Center for Analysis and Prediction of Storms
(CAPS) University of Oklahoma. Temporal invariant surface condition was interpolated from
30” soil maps, land use maps and 10’ Normalized Difference Vegetation Index (NDVI) data
using ARPSSFC package.
2.2 Model parameters used To sufficiently simulate smaller scale atmospheric features related to land surface effect,
our domain horizontal resolution was set to 0.05° × 0.05° while for the vertical grid ARPS uses
a hyperbolic tangent function to stretch the grid interval in this case from 30 m at the surface to
nearly 1.2 km at the top (18 km).
The physics parameterization options include a 1.5-order Turbulent Kinetic Energy-based
subgrid scale closure scheme turbulence, and a planetary boundary layer parameterization.
Radiative forcing is computed according to an atmospheric radiation transfer parameterization
and is updated each 10 minutes.
The Simplified Biosphere (SiB) model, developed by Sellers et al. (1986) and
subsequently revised to SiB2 in Sellers et al. (1996), is used as surface scheme, and the Lin Ice
Microphysics parameterization (Lin et al., 1983) to parameterize cloud and precipitation. For
explicitly resolving convection, the modified Kain-Fritsch convective scheme is better suited
for resolving convection (Truong et al, 2009), the original Kain-Fritsch convective
parameterization (Kain and Fritsch, 1993) was adopted, since LDAS is mainly sensitive to land
surface conditions. The model domain topography is derived from 1 km resolution global
dataset. Land cover was obtained from the global dataset based on the global ecosystem
classification with a spatial resolution of 30” × 30” while its associated static parameters were
derived according to Sellers et al. (1996). Soil types were obtained from global dataset with a
resolution of 30” × 30” and vegetation types were obtained from a 100 resolution global
*Corresponding author (David Kuria). Tel: +254-727-399208. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/303-324.pdf
311
dataset. All these datasets were obtained from CAPS
3. Land Data Assimilation Scheme Boussetta (2005) validated Land Data Assimilation Scheme (LDAS) by assimilating
satellite data and assessed its dynamic downscaling ability. He applied it in a three dimensional
configuration on a mesoscale area of the Tibetan plateau. In his case, he used GEWEX Asian
Monsoon Experiment (GAME) Tibet dataset for 1998. This system combines a land data
assimilation scheme with a coupled land-atmosphere mesoscale model in a recursive cycle. The
system runs by first introducing the initial and boundary atmospheric conditions from NCEP
GFS into the coupled land-atmosphere mesoscale model (ARPSSiB2). This coupled model
then produces forcing for one assimilation window to the land data assimilation system which
optimizes the initial surface variables and feeds them back to the coupled land-atmosphere
model (Figure 2).
Figure 2: Land Data Assimilation Scheme.
Figure 3 shows LDAS assimilation cycle. A typical LDAS assimilation cycle comprises of
the following steps.
Step 1 : ARPS-SiB2 is run for an assimilation window time T to obtain an initial guess and
forcing parameters for LDAS.
Step 2 : LDAS runs for one assimilation window, which feeds back new initial surface
condition for ARPS-SiB2 at time t = t − T.
312 David Kuria, Toshio Koike, Moses Gachari, and Souhail Boussetta
Figure 3: LDAS Assimilation Cycle.
Step 3 : ARPS-SiB2 runs for two assimilation window time 2T, the first window output
being considered as optimal, while the second one serves as forcing for the LDAS run.
In this paper, we used a 24 hour assimilation window (T = 24h). This was due to the need to
have at least one satellite observation to be assimilated during the assimilation period.
3.1 Model operator SiB2 is used as the model operator in the assimilation scheme. It is a dual source model
with fluxes originating from soil surface and canopy. It incorporates simple representations of
vertical soil moisture transport, plant controlled transpiration, interception, evaporation,
infiltration, sensible and heat fluxes through physically based mechanisms.
SiB2 includes three soil layers; a surface soil layer of a few centimeters which acts as a
significant source of direct evaporation when moist; a root zone which is the supplier of soil
moisture to the roots and accounts for transpiration; and a deep soil layer acting as a source for
hydrological base flow and upward recharge to the root zone.
3.2 Observation operator Boussetta (2005) assimilated TRMM Microwave Imager (TMI) satellite brightness
temperature (TB) observations at 10.7 and 19.4 GHz, both polarizations. In this paper, we used
AMSR-E TB observations at 10.7 and 18.7 GHz both polarizations. Additionally, assimilation
of two surrogate observations, namely Polarization Index (PI) proposed by Paloscia and
Pampaloni (1988) at 6.9 GHz, and Index of Soil Wetness (ISW) developed by Fujii and Koike
*Corresponding author (David Kuria). Tel: +254-727-399208. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/303-324.pdf
313
(2001), derived using 18.7 and 6.9 GHz horizontal polarization. These three frequencies’ data
were chosen due to their relative insensitivity to atmospheric conditions. These two
relationships are given as,
(7)
(8)
where v or h in the subscript denote polarization i.e vertical and horizontal respectively at the
given frequency.
Boussetta (2005) used a first order radiative transfer model (RTM) coupled with QH model
of Choudhury et al. (1979) for addressing surface roughness effects. In Kuria et al. (2007) it was
shown that the QH model is not fit for use with high frequency data. Although it has been
widely used, its roughness parameters have to be ‘calibrated’ first, and are thus not physically
based. While this is sufficient in most cases when dealing with frequencies lower than 20 GHz,
the lack of a physical basis in determining these parameters motivated us to consider using the
improved surface emission model validated by Kuria et al. (2007). This surface emission model
is used as the observation operator. Compared to that used in Boussetta (2005), it uses a
physically based treatment of surface roughness effects, thereby improving confidence of
forward modelling. A further refinement was by introducing Polarization Index (PI) and Index
of Soil Wetness (ISW) that describe roughness and moisture conditions as surrogate
observations. We use the variance matrix of the following form to describe the background
co-variance matrix B, used in equation 4.
0 0 0 00 0 0 00 0 0 00 0 0 00 0 0 0
(9)
The observation error covariance matrix (R), used in equation 5, follows a similar form
314 David Kuria, Toshio Koike, Moses Gachari, and Souhail Boussetta
0 0 0 0 00 0 0 0 00 0 0 0 00 0 0 0 00 0 0 0 00 0 0 0 0
(10)
In these cases we assume that all observations are uncorrelated, and model state variables
are uncorrelated too. In Table 2, we list values of observation errors, and in Table 3, values of
background errors used in the observation and background error matrices, respectively as used
in this research. The background covariance matrix was assumed static for simplicity, though
ideally it should be allowed to evolve with the assimilation process, being updated with new
values for use in subsequent steps.
Table 2: Observation errors
Tb10h Tb10v Tb18h Tb18v PI6 ISW618
4K 3K 5K 4K 0.01 0.01
Simulated Annealing was used to minimize the cost function J. It is a heuristic
optimization approach capable of minimizing the variational cost function without using
adjoint models (Ingber, 1993). It avoids problems due to strong non-linearities and
discontinuities in finding the global minimum in the hilly structure of the cost function. It is
based on the analogous approach of metal annealing in thermodynamics (Kirkpatrick et al.,
1983).
Table 3: Background errors
Tg Td Mvsfc Mvrt Mvdp
3K 2K 0.04 0.03 0.02
4. Results and discussion We use ARPS/LDAS to simulate land surface conditions using AMSR-E lower frequency
(6.925, 10.65, and 18.7 GHz) brightness temperatures (TBs) for Tibetan plateau. This
*Corresponding author (David Kuria). Tel: +254-727-399208. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/303-324.pdf
315
simulation was for three days from 00:00 UTC on 19th August 2004 – 00:00 UTC on 22nd
August 2004.
(a)
(b)
Figure 4: Comparison of time-series land surface variables (a) surface temperature and (b)
surface soil moisture at BJ site
4.1 Time series comparison We run ARPS/LDAS assimilation as one case, and plain ARPS as second case. Both
models were run for 72 hours from 00:00 UTC 19/08/2004 to 00:00 UTC 22/08/2004. In Figure
4 we show comparisons of retrieved surface variables at BJ site.
316 David Kuria, Toshio Koike, Moses Gachari, and Souhail Boussetta
(a)
(b)
Figure 5: Time series soil moisture product comparison along 91.9°E (a) ARPS case and
(b) LDAS case
We prepared a time series plot covering the duration 0 – 48h, and we compare this with an
in-situ dataset. This in-situ data set comprises hourly soil moisture records at 3cm and 10cm
depth, and soil temperature at the same depths. Since we are using Microwave observations
which sense shallow depths, we will analyze only near surface variables (3cm depth). During
*Corresponding author (David Kuria). Tel: +254-727-399208. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/303-324.pdf
317
this time period, we have two AMSR-E overpasses, descending overpass at 19:41 UTC on 19th
August and ascending overpass 06:42 UTC on 20th August.
(a)
(b)
Figure 6: Time series surface precipitation comparison along 91.9°E (a) ARPS case and (b)
LDAS case
318 David Kuria, Toshio Koike, Moses Gachari, and Souhail Boussetta
We begin by considering surface temperature (Figure 4(a)).While bearing in mind the fact
that we are comparing grid averaged values with point observations, we note that (i) the diurnal
variation of near surface temperature observed is simulated by both cases, (ii) ARPS derived
surface temperature have much higher peaks and valleys than ARPS/LDAS case and (iii) in
general, the ARPS/LDAS configuration gives better agreement with the in-situ dataset, though
the gap between peaks/valley can vary by as much as 5 K.
Considering near surface soil moisture (Figure 4(b)), there is remarkable agreement with
in-situ dataset for ARPS/LDAS case. ARPS case is over-predicting soil moisture by as much as
5%. At the time slots corresponding to AMSR-E overpass times it can be noted that
ARPS/LDAS and in-situ datasets match perfectly, and also that in the interval between these
times, the simulations follows observations almost perfectly.
In Figure 5 we show comparison of time series moisture product along longitude 91°E.We take
the same period (0 – 48h) for this analysis. It is clear that the ARPS case (Figure 5(a)) is wetter
than the corresponding ARPS/LDAS case. We note that ARPS case is wettest at the edges,
alluding to the strong influence of initial and boundary conditions from GFS reanalysis data.
The situation is different in ARPS/LDAS case. ARPS seems to get wetter implying heavy
precipitation events at the beginning (6 hours after start) and about 30 hours after start. We have
similar events in ARPS/LDAS but their duration and intensity is not as high as in ARPS case.
Figure 6 depicts time series precipitation for the same period. As mentioned above, it can be
seen that ARPS is producing higher precipitation, in intensity and distribution. We note too that
ARPS precipitating durations are longer than ARPS/LDAS precipitation durations.
4.2 Comparison of simulation at hour closest AMSRE overpass time We consider 07:00 UTC on August 20th 2004 for analysis of soil moisture retrieval. Figure
7 shows simulation following the same convention, i.e. ARPS case (Figure 7(a)) and
ARPS/LDAS case (Figure 7(b)). Soil moisture distribution in ARPS case is strongly influenced
by the initial conditions giving rather high forecasts of soil moisture.
Its soil moisture distribution follows GFS soil moisture distribution (not shown). Soil
moisture distribution in ARPS/LDAS case by assimilating observed TBs shows improved
distribution.
*Corresponding author (David Kuria). Tel: +254-727-399208. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/303-324.pdf
319
(a)
(b)
Figure 7: Moisture comparison (a) ARPS and (b) LDAS for August 20th 2004.
Figure 8: GPCP Cumulative surface precipitation
To validate this hypothesis, we consider the relationship between precipitation and soil
moisture. It is known that the occurrence of a precipitation event invariably leads to an increase
in soil moisture, thus in the absence of quantitative soil moisture observations or estimates,
320 David Kuria, Toshio Koike, Moses Gachari, and Souhail Boussetta
observed precipitation (or precipitation deduced from observations) can be used to give a
qualitative assessment of soil moisture.
We include Global Precipitation Climatology Project (GPCP) daily cumulative
precipitation data for the site on August 20th, to assist in verifying our hypothesis that
ARPS/LDAS case is significantly better than ARPS case. GPCP provides daily global gridded
values of cumulative precipitation, for the period from October 1996 – December 2006
(Huffman et al., 2001). The product considered for this validation exercise is the 1° resolution
daily precipitation dataset. Figure 8 shows this GPCP dataset for the spatial domain considered
in this paper. Comparing this with our simulations, it can be noted that while the resolution of
GPCP is very coarse, we have similar pattern with the ARPS/LDAS case. The ARPS case is
completely different with the observed precipitation pattern.
Considering surface temperature simulations (Figure 9), surface temperature
representation in both cases follows similar patterns, but on closer inspection, it can be noted
that ARPS simulated generally higher temperatures than ARPS/LDAS case.
(a) (b)
Figure 9: Surface temperature comparison (a) ARPS and (b) LDAS for August 20th 2004
Additionally, when we compare ARPS/LDAS case with terrain map (Figure 1), we note
that the temperature distribution shows agreement with terrain map (high temperature
*Corresponding author (David Kuria). Tel: +254-727-399208. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/303-324.pdf
321
corresponding to valley area, and low temperatures corresponding to mountain areas).
We also note that in the central region of ARPS/LDAS case we have colder temperatures.
This region corresponds could be experiencing a precipitation event at this time (bearing in
mind the time series results shown in Figure 6). It can thus be argued that ARPS/LDAS
simulated surface temperatures, while not matching observed conditions perfectly (see Figure
4(a)), does provide a much improved estimation of surface temperatures.
5. Conclusion Data Assimilation potential in improving model predictability has been investigated in this
paper. We have shown that by using a physically based surface emission model as the
observation operator we have improved estimation of near surface conditions. Near surface soil
moisture retrievals using ARPS/LDAS was shown to follow observed situation well. Surface
temperature retrieval was shown to be better when we use the assimilation system than if we did
not. While the match between observations and assimilated simulations is not perfect, there is
nevertheless a good agreement with the discrepancies being attributed to the fact that the in-situ
measurements were made at point locations while the assimilated TBs were obtained over areal
extents representing the satellite footprint resampled to a 10km spatial resolution.
From the results presented, we showed that in general, soil moisture estimation without
assimilation is higher than the corresponding assimilation case. This can be in part due to the
uncertainties in modelling microphysics and convection in the adopted mesoscale model. We
have demonstrated that by using LDAS, satellite TB observations can be used to improve soil
moisture and surface temperature estimations. While both cases depend on initial conditions,
poor initial conditions were demonstrated as severely impacting the non assimilation case as the
assimilation case is able to recover by assimilating passive microwave TBs. This means that if
uncertainties in mesoscale modelling are resolved, then assimilation of lower frequency
microwave TBs will yield much more reliable soil moisture estimates.
It has been demonstrated that by improving the land surface conditions, the surface
precipitation rates also improve which if therefore used to feed the atmosphere component of a
mesoscale model will in turn yield improved estimation of the atmosphere conditions. In such a
322 David Kuria, Toshio Koike, Moses Gachari, and Souhail Boussetta
scheme, the modified Kain-Fritsch convection scheme can address convection while a
microphysics scheme such as the Schultz scheme (Schultz, 1995) addressing the five main
hydrometeor categories can be used.
Other satellite platforms operating at microwave frequencies such as the Tropical Rainfall
Monitoring Mission and the future Global Precipitation Mission, together with AMSR-E can
provide periodic passive microwave data (brightness temperatures) which can be used in the
LDAS presents, to improve estimation and forecasting the evolution of surface conditions (soil
moisture, surface temperature among others).
6. Acknowledgement This study was carried out as part of the CEOP and Verification Experiment for
AMSR/AMSR-E. Model validation data were provided by the CEOP University of Tokyo
Data Archiving Manager Mr. Katsunori Tamagawa. Dr. Kenji Taniguchi provided in-situ
dataset. The authors would like to thank them for their support towards this research effort.
A very special thank you is due to Associate Professor Dr. Mirza Raza and Dr. Mohammed
Rasmy for insightful comments, helping clarify and improve the manuscript.
7. References Bannister, R.N., (2001). Elementary 4D-VAR. Technical report, DARC, University of Reading.
Boussetta, S., (2005). Development of a Land-Atmosphere Coupled Data Assimilation System for physical downscaling. PhD thesis, University of Tokyo.
Choudhury, B.J., Schmugge, T.J., Chang, A. and Newton, R.W., (1979). Effect of surface roughness on the microwave emission from soil. Geophysical Research, 84, 5699–5706.
Daley, R., 1991, Atmospheric Data Analysis. Cambridge University Press.
Fujii, H. and Koike, T., (2001). Development of a TRMM/TMI algorithm for precipitation in the Tibetan Plateau by considering effects of land surface emissivity. Journal of the Meteorological Society of Japan, 79, 475–483.
Huffman, G.J., Adler, R., Morrissey, M., Curtis, S., Joyce, R., McGavock, B. and Susskind, J., (2001). Global precipitation at one-degree daily resolution from multi-satellite observations. Journal of Hydrometeorology, 2, 36–50.
Ide, K., Courtier, P., Gill, M. and Lorenc, A.C., (1997). Unified Notation for Data Assimilation: Operational, Sequential and Variational. Journal of the Meteorological Society of
*Corresponding author (David Kuria). Tel: +254-727-399208. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/303-324.pdf
323
Japan, 1–20.
Ingber, L., (1993). Simulated annealing: Practice versus theory. Mathematical and Computer Modelling, 18, 29–57.
Kain, J.S. and Fritsch, J.M., (1993). Convective parameterization for mesoscale models: The Kain-Fritsch scheme, the representation of cumulus convection in Numerical Models, Meteorology Monogram . American Meteorology Society.
Kirkpatrick, S.C., Jr., C.D.G. and Vecchi, M.P., (1983). Optimization by Simulated Annealing. Science, 220, 671–680.
Kuria, D., Koike, T., Lu, H., Tsutsui, H. and Graf, T., 2007, Field-supported verification and improvement of a passive microwave surface emission model for rough, bare and wet soil surfaces by incorporating shadowing effects. IEEE Transactions on Geoscience and Remote Sensing, 45, 1207–1216.
Lin, Y.L., Farley, R.D. and Orville, H.D., (1983). Bulk parameterization of the snow field in a cloud model. Journal of Climate and Applied Meteorology, 22, 1065–1089.
Mahadevan, P., Koike, T., Fujii, H., Tamagawa, K., Li, X. and Kaihotsu, I., (2007). Modification and application of the satellite based Land Data Assimilation Scheme for very dry soil regions using AMSR-E images: Model validation for Mongolia — a CEOP data platform. Journal of the Meteorological Society of Japan, 85A, 243–260.
Mahadevan, P., Koike, T. and Li, X., 2003, A New Satellite-Based Data Assimilation Algorithm to Determine Spatial and Temporal Variations of Soil Moisture and Temperature Profiles. Journal of the Meteorological Society of Japan, 81, 1111–1135.
Njoku, E.G., (1999). AMSR Land surface parameters: Algorithm theoretical basis document, NASA JPL.
Paloscia, S. and Pampaloni, P., (1988). Microwave Polarization Index for Monitoring Vegetation Growth. IEEE Transactions on Geoscience and Remote Sensing, 26, 617–621.
Reichle, R.H., Entekhabi, D. and McLaughlin, D.B., (2001). Downscaling of radio brightness measurements for soil moisture estimation: A four-dimensional variational data assimilation approach. Water Resources Research, 37, 2353–2364.
Sellers, P.J., Los, S.O., Tucker, C.J., Justice, C.O., Dazlich, D.A., Collatz, G.J. and Randall, D.A., 1996, A revised land surface parameterization (SiB2) for atmospheric GCMs, Part II: the generation of global fields of terrestrial biophysical parameters from satellite data. Journal of Climate, 9, 706–737.
Sellers, P.J., Sud, Y.C. and Dalcher, A., 1986, A simple biosphere model (SiB) for use within General Circulation Models. Journal of the Atmospheric Sciences, 43, 505–531.
Schultz, P., 1995. An explicit cloud physics parameterization for operational numerical weather prediction. Monthly Weather Review, 123, 3331 – 3343.
324 David Kuria, Toshio Koike, Moses Gachari, and Souhail Boussetta
Tsang, L., Kong, J.A.U. and Shin, R.T., 1985, Theory of Microwave remote sensing. Wiley and Sons, New York.
Truong, N. M., Tien, T. T., Pielke Sr., R. A., Castro, C. L. and Leoncini, G., (2009). A modified Kain-Fritsch scheme and its application for the simulation of an extreme precipitation event in Vietnam. Monthly Weather Review, 137, 766 – 789.
Ulaby, F.T., Moore, R.K. and Fung, A.K., (1981). Microwave remote sensing: Fundamentals and radiometry, Vol. 1. Artech House, Norwood, MA.
Wilheit, T., Kummerow, C. and Ferraro, R., (1999). EOS/AMSR Rainfall. Algorithm theoretical basis document.
Wilks, D.S., (1999). Multisite downscaling of daily precipitation with a stochastic weather generator. Climate Research, 11, 125–136.
Xue, M., Wang, D., Gao, J., Brewster, K. and Droegemeier, K.K., (2003). The Advanced Regional Prediction System (ARPS), storm-scale numerical weather prediction and data assimilation. Meteorology and Atmospheric Physics, 82, 139–170.
Yang, K., Chen, Y.Y. and Qin, J., (2009). Some practical notes on the land surface modeling in the Tibetan Plateau. Hydrology and Earth System Sciences Discussions, 6, 1291–1320.
David Kuria is a Senior Lecturer in the department of Geomatic Engineering and Geospatial Information Science of the Kimathi University College of Technology. He received his B. Sc (Surveying) with Honors from the University of Nairobi (Kenya) in 1998. He holds an M. Sc (Photogrammetry and Geoinformatics) from the Stuttgart University of Applied Sciences (Germany) awarded in 2003. He undertook Ph.D. studies at the University of Tokyo (Japan) completing it in 2007. He has lectured for more than 4 year at the Jomo Kenyatta University of Agriculture and Technology. Dr. Kuria’s current interests are in webmapping, climate research and geospatial application development.
Toshio Koike received the B.Eng., M.Eng., and D.Eng. degrees from the University of Tokyo, Tokyo, Japan, in 1980, 1982, and 1985, respectively. He was a Research Associate at the University of Tokyo in 1985 and was appointed as an Assistant Professor at the same university in 1986. He was also appointed as an Associate Professor at Nagaoka University of Technology, Nagaoka, Japan in 1992. He has been a Professor at the River and Environmental Engineering Laboratory, Department of Civil Engineering, University of Tokyo since 2000. He is the Lead Scientist of the Coordinated Enhanced Observing Period project. Prof. Koike’s research interests are in hydrology, water resources, satellite remote sensing, climate change, and Asian monsoons.
Souhail Boussetta received B.Eng, and M.Eng degrees from the National school of Engineering of Tunis at the University of Tunis in 1991 and 1993 respectively, and a Ph.D from the University of Tokyo, Japan in 2005. He was a Research Associate at the University of Tokyo in 2006 and was appointed as Assistant Professor for EDITORIA at the University of Tokyo in 2007. He is currently a scientist at the European Centre for Medium range Weather Forecast. Dr. Boussetta’s research interests include Land surface parameterization, land data assimilation, and satellite remote sensing applied to water resources.
Peer Review: This article has been internationally peer-reviewed and accepted for publication
according to the guidelines given at the journal’s website.
*Corresponding author (Kondapalli Siva Prasad). Tel/Fax: +91-9849212391 E-mail addresses: [email protected] 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/325-336.pdf
325
International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
http://www.TuEngr.com, http://go.to/Research
Prediction of Weld Pool Geometry in Pulsed Current Micro Plasma Arc Welding of SS304L Stainless Steel Sheets Kondapalli Siva Prasada*, Ch. Srinivasa Raob, D. Nageswara Raob
a Department of Mechanical Engineering, Anil Neerukonda Institute of Technology & Sciences, INDIA b Department of Mechanical Engineering, Andhra University, INDIA A R T I C L E I N F O
A B S T RA C T
Article history: Received 21 March 2011 Received in revised form 27 May 2011 Accepted 13 June 2011 Available online 14 June 2011 Keywords: Pulsed Current MPAW, SS304L, ANOVA, Bead Geometry
Pulsed Micro Plasma Arc Welding (MPAW) is a metal joining technique widely used in manufacturing of thin sheet components due to its inherent properties. The weld quality and productivity are controlled by the process parameters. The paper discuses about development of mathematical models for weld pool geometry of stainless steel 304L sheets. Design of experiments based on full factorial design is employed for the development of a mathematical model correlating the important controlled pulsed MPAW process parameters like peak current, background current, pulse and pulse width with front width, back width, front height and back height. The developed mode has been checked for adequacy based on ANOVA analysis. Weld bead parameters obtained by the models are found to confirm actual values with high accuracy. Using these models effect of pulsed MPAW process parameters on weld pool geometry are studied.
2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Some Rights Reserved.
1. Introduction The plasma welding process was introduced to the welding industry in 1964 as a method
of bringing better control to the arc welding process in lower current ranges (Modern
Application News, 1999 ). Today, plasma retains the original advantages it brought to the
2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. 2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies.
326 K. Siva Prasad, Ch.Srinivasa Rao, D.Nageswara Rao
industry by providing an advanced level of control and accuracy to produce high quality
welds in both miniature and pre precision applications and to provide long electrode life for
high production requirements at all levels of amperage. Plasma welding is equally suited to
manual and automatic applications. It is used in a variety of joining operations ranging from
welding of miniature components to seam welding to high volume production welding and
many others.
The welding optimization literature frequently reveals correlation among responses.
(D.K.Zhang et.al,2010) studied the influence of welding current, arc voltage, welding speed,
wire feed rate and magnitude of ion gas flow on front melting width, back melting width and
weld reinforcement of Alternating Current Plasma Arc Welding process of LF6 Aluminum
alloy of thickness 3mm using Artificial Neural Network- Back Propagation algorithm.
(Sheng-Chai Chi et. al ,2001) developed an intelligent decision support system for Plasma
Arc Welding of stainless steel plates of thickness range from 3 to 9 mm based on fuzzy Radial
Basis Function (RBF) neural network by performing experiments using Taguchi method. (Y.
F. Hsiao et. Al,2008) studied the optimal parameters process of plasma arc welding of SS316
of thickness 4mm by Taguchi method with Grey relational analysis is studied. Torch stand-
off, welding current, welding speed and plasma gas flow rate (Argon) were chosen as input
variables and welding groove root penetration, welding groove width, front-side undercut
were measured as output parameters. (K.Siva et.al, 2008) used central composite rotatable full
factorial design matrix and conducted experiments in optimization of weld bead geometry in
Plasma arc hardfaced austenitic stainless steel plates using Genetic Algorithm.
(A.K.Lakshminarayan et.al, 2008) predicted the Dilution of Plasma Transferred Arc
Hardfacing of Stellite on Carbon Steel using Response Surface Methodology (RSM). (V
Balasubramanian et.al, 2009) used Response Surface Methodology to predict and optimize the
percentage of dilution of iron-based hardfaced surface produced by the Plasma transferred arc
welding process.
From the earlier works, it has been observed that much work is not reported so far to
investigate the effect of pulsed current MPAW process parameters on stainless steel weld
characteristics; and developing the related mathematical models to predict the same especially
for welding of thin stainless steel sheets. Hence an attempt was made to correlate important
pulsed MPAW process parameters to bead geometry of thin AISI 304L stainless steel welds
*Corresponding author (Kondapalli Siva Prasad). Tel/Fax: +91-9849212391 E-mail addresses: [email protected] 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/325-336.pdf
327
by developing mathematical models. The models developed will be very useful to predict the
weld pool geometry parameters for desired bead geometry. A statistically designed
experiment based on full factorial design has employed for the development of mathematical
models (Montgomery DC ,2005).
Figure 1: Typical weld pool geometry.
2. Experimental procedure Austenitic stainless steel sheets of type AISI 304L 100×50×0.25 mm are welded
autogenously with square butt joint without edge preparation. To evaluate the quality of
MPAW welds, measurements of the front width, back width, front height and back height of
the weld pool are considered. Figure 1 indicates the typical weld pool geometry. Table 1
indicates the chemical composition of AISI 304L stainless steel sheet. Experiments are
conducted using the Pulsed Micro Plasma Arc Welding (MPAW) process with pulse DCEN.
Industrial pure and commercial grade argon gases are used for shielding and back purging,
respectively. Automatic voltage control available in the welding equipment is used. Fixture
variation effects are not considered as the same setup has been used throughout the
experiment. Some of the welding process parameters are fixed based on earlier work and also
from the trial run so as to obtain full penetration weld. Trial runs are conducted to find the
limits of each controllable process parameter so as to obtain full penetration weld, free from
any visible defects. Because of computational ease and enhanced interpretability of the
models, parameters are converted to coded form for developing mathematical models
(Giridharan PK et.al, 2007). The upper limit of a factor is coded as +1 and the lower limit as
328 K. Siva Prasad, Ch.Srinivasa Rao, D.Nageswara Rao
−1. Table 2 represents the levels determined for process variables with their levels, units and
notations for the pulsed MPAW process. Table 3 represents the fixed pulsed MPAW process
parameters and their values.
Table 1: Chemical composition of austenitic stainless steel (AISI 304L) sheet.
Elements Chromium Silicon Nickel Carbon Manganese Iron
% by weight
18.2% 0.5%
8.5% 0.015%
1.6% Balance
Table 2: Input variables and their levels
Levels SI No Input Factor Units -1 +1 1 Peak Current Amps 6.5 7.5 2 Back Current Amps 3.5 4.5 3 Pulse No’s /Sec 30 50 4 Pulse width % 40 60
Table 3: Fixed pulsed MPAW process parameters and their values.
Power source Secheron Micro Plasma Arc Machine (Model: PLASMAFIX 50E)
Polarity DCEN Mode of operation Pulse mode Electrode 2% thoriated tungsten electrode Electrode Diameter 1mm Plasma gas Argon & Hydrogen Plasma gas flow rate 6 Lpm Shielding gas Argon Shielding gas flow rate 0.4 Lpm Purging gas Argon Purging gas flow rate 0.4 Lpm Copper Nozzle diameter 1mm Nozzle to plate distance 1mm Welding speed 260mm/min Torch Position Vertical Operation type Automatic
From the Design of Experiments and due to wide range of input process parameters, the
present work is limited to use four factors, two levels, full factorial design matrix in order to
simplify the present problem. Table 4 shows the measured values of output response by
taking an average value of three samples of 16 sets of coded conditions used in the form of
design matrix. The 16 experiments have been formulated as per 24 (two levels and four
factors) factorial design.
*Corresponding author (Kondapalli Siva Prasad). Tel/Fax: +91-9849212391 E-mail addresses: [email protected] 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/325-336.pdf
329
3. Recording the Responses Three samples are cut from the welded specimens at an interval of 25mm and mounted in
Bakelite powder, polished and etched with Oxalic acid as per ASTM E3 and ASTM E340.
Weld pool geometries are measured using Metallurgical Microscope make Dewinter
Technologie, Model No. DMI-CROWN-II. Figure 2 represents the Photomacrographs of a
typical weld specimen showing the bead profile at 100X magnification.
Figure 2: Photomacrographs of a typical weld specimen.
Table 4: Welding parameters and responses for the full factorial design.
Exp No
Peak Current
(PC)
Back Current
(BC)
Pulse (P)
Pulse Width (PW)
Front Width
Back Width
Front Height
Back Height
Amperes Amperes No’s % Microns Microns Microns Microns 1 7.5 3.5 30 60 1579.22 1499.50 63.209 57.775 2 6.5 4.5 30 60 1486.59 1361.64 59.137 49.443 3 7.5 4.5 50 60 1383.04 1301.22 53.953 48.422 4 6.5 3.5 50 40 1539.88 1480.60 54.191 49.422 5 7.5 4.5 30 60 1582.92 1506.41 76.886 71.209 6 7.5 3.5 50 40 1404.63 1283.25 71.247 65.947 7 6.5 3.5 30 60 1477.09 1393.14 60.583 54.737 8 6.5 3.5 50 60 1451.98 1372.69 61.896 54.251 9 6.5 3.5 30 40 1530.30 1453.96 57.514 52.538 10 6.5 4.5 50 60 1382.42 1305.11 63.619 58.265 11 7.5 3.5 50 60 1392.70 1337.14 59.083 54.855 12 6.5 4.5 30 40 1543.53 1466.85 42.855 36.559 13 7.5 3.5 30 40 1581.70 1537.70 48.824 42.514 14 7.5 4.5 50 40 1503.05 1436.88 64.101 59.595 15 7.5 4.5 30 40 1547.92 1474.37 52.275 46.553 16 6.5 4.5 50 40 1486.94 1408.72 65.613 58.092
4. Development of Mathematical Models A low-order polynomial is employed for developing the mathematical model for
predicting weld pool geometry. Equation (1) represents a typical mathematical model, in
which the response is well modeled by a linear function of the independent variables.
330 K. Siva Prasad, Ch.Srinivasa Rao, D.Nageswara Rao
Table 5: ANOVA test results.
ANOVA for Front Width Source Main Effects 2-Way Interactions 3-Way Interactions Residual Error Total R2 Value =94.05
DF 4 6 4 1
15
Seq SS 25659 23462 23142 4575
76837
Adj SS 25659 23462 23142 4575
Adj MS 6415 3910 5785 4575
F 1.40 0.85 1.26
ANOVA for Back Width Source Main Effects 2-Way Interactions 3-Way Interactions Residual Error Total R2 Value = 96.24
DF 4 6 4 1
15
Seq SS 35868 38078 19057 3633
96636
Adj SS 35868 38078 9057 3633
Adj MS 8967 6346 4764 3633
F 2.47 1.75 1.31
ANOVA for Front Height Source Main Effects 2-Way Interactions 3-Way Interactions Residual Error Total R2 Value = 95.18
DF 4 6 4 1
15
Seq SS 499.22 335.64 157.23 50.23
1042.32
Adj SS 499.22 335.64 157.23 50.23
Adj MS 124.80 55.94 39.31 50.23
F 2.48 1.11 0.78
ANOVA for Back Height Source Main Effects 2-Way Interactions 3-Way Interactions Residual Error Total R2 value = 97.39
DF 4 6 4 1
15
Seq SS 487.77 336.44 233.81 28.32
1086.34
Adj SS 487.77 336.44 233.81
32
Adj MS 121.94 56.07 58.45 28.32
F 4.31 1.98 2.06
Where SS =Sum of Squares, MS=Mean Square, F=Fishers ratio
Y = β + β1 x1 + β2 x2 + …._ βx xx + ∈ (1)
The regression coefficients were calculated using MINITAB14 software and Equations
(2), (3), (4), and (5) represent the developed mathematical models with welding parameters in
coded form.
Front Width =1492.12+(38.45*X1)-(6.42*X2)+(7.07*X3)+(5.85*X4) +(26.12*X1*X2)
+(9.6*X1*X3)+(24.67*X1*X4)+(2.1*X2*X3)+(4.17*X2*X4)-(7.86*X3*X4)+
(16.27*X1*X2*X3)+(28.66*X1*X2*X4)-(10.35*X1*X3*X4)-(15.91*X2*X3*X4) (2)
*Corresponding author (Kondapalli Siva Prasad). Tel/Fax: +91-9849212391 E-mail addresses: [email protected] 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/325-336.pdf
331
Back Width =1413.7+(46.21*X1)-(5.53*X2)-(1.79*X3)+(8.53*X4)-(34.34*X1*X2)
+(15.69*X2*X3)+(27.73*X1*X4)+(9.46*X2*X3)-(1.52*X2*X4)-(9.7*X3*X4)+
(10.7*X1*X2*X3)+(28.4*X1*X2*X4)-(10.32*X1*X3*X4)-(12.8*X2*X3*X4) (3)
Front Height = 59.687-(1.253*X1)-(0.756*X2)+(3.032*X3)-(4.457*X4)
+(1.146*X1*X2)+(3.509*X1*X3)-(1.707*X1*X4)-(1.891*X2*X3)+(0.676*X2*X4)
-(0.639*X3*X4)+(0.937*X1*X2*X3)-(0.304*X1*X2*X4)+(0.529*X1*X3*X4)+
(2.929*X2*X3*X4) (4)
Back Height = 53.761-(1.212*X1)-(0.513*X2)+(2.845*X3)-(4.545*X4)
+(0.637*X1*X2)+(3.731*X1*X3)-(1.436*X1*X4)-(1.886*X2*X3)+(0.671*X2*X4)
-(0.795*X3*X4)+(0.571*X1*X2*X3)-(0.195*X1*X2*X4)+(1.25*X1*X3*X4)
+(3.562*X2*X3*X4) (5)
Table 6: Comparison of actual and predicted values of responses.
Front Width Back Width Front Height Back Height Run
Order Actual Predicted Actual Predicted Actual Predicted Actual Predicted
1 1579.22 1562.31 1499.5 1484.43 63.209 61.4371 57.775 56.4446 2 1486.59 1469.68 1361.64 1346.57 59.137 57.3651 49.443 48.1126 3 1383.04 1399.94 1301.22 1316.28 53.953 55.7249 48.422 49.7524 4 1539.88 1556.79 1480.6 1495.67 54.191 55.9629 49.422 50.7524 5 1582.92 1566.01 1506.41 1491.34 76.886 75.1141 71.209 69.8786 6 1404.63 1421.54 1283.25 1298.32 71.247 73.0189 65.947 67.2774 7 1477.09 1460.18 1393.14 1378.07 60.583 58.8111 54.737 53.4066 8 1451.98 1435.07 1372.69 1357.62 61.896 60.1241 54.251 52.9206 9 1530.3 1513.39 1453.96 1438.89 57.514 55.7421 52.538 51.2076
10 1382.42 1365.51 1305.11 1290.04 63.619 61.8471 58.265 56.9346 11 1392.7 1409.60 1337.14 1352.21 59.083 60.8549 54.855 56.1854 12 1543.53 1560.44 1466.85 1481.92 42.855 44.6269 36.559 37.8894 13 1581.7 1564.79 1537.7 1522.63 48.824 47.0521 42.514 41.1836 14 1503.05 1519.95 1436.88 1451.95 64.101 65.8729 59.595 60.9254 15 1547.92 1564.83 1474.37 1489.44 52.275 54.0469 46.553 47.8834 16 1486.94 1503.85 1408.72 1423.79 65.613 67.3849 58.092 59.4224
5. Checking the Adequacy of the Mathematical Models The adequacy of the developed models is tested using Analysis of Variance (ANOVA)
technique. As per this technique, if the calculated value of Fratio of the developed model is less
332 K. Siva Prasad, Ch.Srinivasa Rao, D.Nageswara Rao
than the standard Fratio (from F-table) value at a desired level of confidence (say 99%), then
the model is said to be adequate within the confidence limit. ANOVA test results of all the
responses are presented in Table 5.
The ANOVA table (Table 5) reveals that all the calculated F values are less than standard
table F value; hence developed mathematical models are adequate.
6. Results & Discussion Table 6 represents the predicted values of weld pool geometry. Figures 3, 4, 5, and 6
represents the scatter plots of weld bead parameters, indicating that the actual and predicted
values of Weld pool geometry parameters are very close to each other.
Predicted
Act
ua
l
160015501500145014001350
1600
1550
1500
1450
1400
1350
Scatterplot of Front Width
Predicted
Act
ua
l
8070605040
80
70
60
50
40
Scatterplot of Front Height
Figure 3: Scatter plot of Front Width Figure 5: Scatter plot of Front Height
Predicted
Act
ua
l
1550150014501400135013001250
1550
1500
1450
1400
1350
1300
1250
Scatterplot of Back Width
Predicted
Act
ua
l
757065605550454035
70
65
60
55
50
45
40
35
Scatterplot of Back Height
Figure 4: Scatter plot of Back Width Figure 6: Scatter plot of Back Height
Figures 7, 8, 9, 10, 11, 12, 13, and 14 represent the main and interaction effects of
different pulsed MPAW process parameters on the weld pool geometry. From Figures 7, 8, 9,
and 10, it is understood from the results that peak current & pulse had more significant effect
on weld pool geometry compared to back current and pulse width.
*Corresponding author (Kondapalli Siva Prasad). Tel/Fax: +91-9849212391 E-mail addresses: [email protected] 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/325-336.pdf
333
Me
an
of
FR
ON
T W
IDT
H
1-1
1525
1500
1475
14501-1
1-1
1525
1500
1475
14501-1
PEAK CURRENT BACK CURRENT
PULSE PULSE WIDTH
Main Effects Plot (data means) for FRONT WIDT H
Me
an
of
BA
CK
WID
TH
1-1
14601440142014001380
1-1
1-1
14601440142014001380
1-1
PEAK CURRENT BACK CURRENT
PULSE PULSE WIDTH
Main Effects Plot (data means) for BA CK WIDT H
Figure 7: Main effects for Front Width. Figure 8: Main effects for Back Width.
Me
an
of
FR
ON
T H
EIG
HT
1-1
64626058
561-1
1-1
6462605856
1-1
PEAK CURRENT BACK CURRENT
PULSE PULSE WIDTH
Main Effects P lot (data means) for FRONT HEIGHT
Me
an
of
BA
CK
HE
IGH
T
1-1
58
5654
5250
1-1
1-1
5856
54
5250
1-1
PEAK CURRENT BACK CURRENT
PULSE PULSE WIDTH
Main Effects Plot (data means) for BA CK HEIGHT
Figure 9: Main effects for Front Height. Figure 10: Main effects for Back Height.
As the peak current and number of pulses increases, heat input also increases, which
leads to higher penetration and hence wider front and back widths. As the widths become
wider the slopes become smaller, thereby decreasing the front and back heights. As the pulse
with increases the weld pool geometry parameters decreases because of lower cooling rate of
weld metal.
Back current is helpful in maintain the continuous arc, however increasing the back
current decrease the weld pool geometry parameters because of large variation in pulse/sec.
334 K. Siva Prasad, Ch.Srinivasa Rao, D.Nageswara Rao
PEAK CURRENT
PULSE
PULSE WIDTH
BACK CURRENT
1-1 1-1 1-1
1550
1500
1450
1550
1500
1450
1550
1500
1450
PEAKCURRENT
-11
BACKCURRENT
-11
PULSE-11
Interaction Plot (data means) for FRONT WIDT H
PEAK CURRENT
PULSE
PULSE WIDTH
BACK CURRENT
1-1 1-1 1-11500
1400
1500
1400
1500
1400
PEAKCURRENT
-11
BACKCURRENT
-11
PULSE-11
Interaction Plot (data means) for BA CK WIDT H
Figure 11: Main effects for Back Height. Figure 12: Interaction effect for Front Width.
PEAK CURRENT
PULSE
PULSE WIDTH
BACK CURRENT
1-1 1-1 1-1
65
60
55
65
60
55
65
60
55
PEAKCURRENT
-11
BACKCURRENT
-11
PULSE-11
Interaction Plot (data means) for FRONT HEIGHT
PEAK CURRENT
PULSE
PULSE WIDTH
BACK CURRENT
1-1 1-1 1-1
60
55
50
60
55
50
60
55
50
PEAKCURRENT
-11
BACKCURRENT
-11
PULSE-11
Interaction Plot (data means) for BA CK HEIGHT
Figure 13: Interaction effect for Front Height. Figure 14: Interaction effect for Back Height.
From Figures 11 and 12, it is understood that the interaction effect on Front Width and
Back Width are almost same i.e. the combined effect peak current and back current decrease
in Front Width and Back Width, the combined effect of Peak Current and pulse increase the
Front and Back Width and the combined effect of peak current and pulse width decrease in
Front and Back Width.
From Figures 13 and 14 it is understood that the interaction effect on Front Width and
Back Width are almost same i.e. the combined effect peak current and back current decrease
in Front Width and Back Width, the combined effect of Peak Current and pulse decrease the
Front and Back Width and the combined effect of peak current and pulse width increase in
Front and Back Width.
Finally from Figures 11 to 14, it is understood that peak current and number of pulses has
more significant effect on weld pool geometry parameters over other weld parameters.
*Corresponding author (Kondapalli Siva Prasad). Tel/Fax: +91-9849212391 E-mail addresses: [email protected] 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/325-336.pdf
335
7. Conclusion From the developed mathematical models predicted values of weld pool geometry
parameters were computed and found to be very close to actual values. Front Width & Back
Width increases with Peak Current & Pulse, where as it decreases with Back Current and
Pulse Width. Front Height and Back Height decreases with Peak Current, Back Current, Pulse
and Pulse Width. The present study is limited to four process parameters namely peak
current, back current, pulse and pulse width for predicting the weld pool geometry. One may
consider other factors like welding speed, nozzle stand of distance, plasma and shielding gas
flow rates and more levels for improving the statistical mathematical model.
8. Acknowledgements We express our sincere thanks to Shri. R.Gopla Krishnan, Director, M/s Metallic Bellows
(I) Pvt Ltd, Chennai, INDIA and management of MVGR Engineering College, Vizianagaram,
INDIA for their support to carry out experimentation. A very special thank you is due to
Associate Professor Dr. Bovornchok Poopat for insightful comments, helping clarify and
improve the manuscript.
9. References Lakshinarayana.A.K, Balasubramanian.V, Varahamoorthy.R and Babu.S. (2008). Predicted
the Dilution of Plasma Transferred Arc Hardfacing of Stellite on Carbon Steel using Response Surface Methodology, Metals and Materials International, Vol.14, No.6, pp.779-789.
Balasubramanian.V, Lakshminarayanan.A.K, Varahamoorthy.R and Babu.S. (2009). Application of Response Surface Methodolody to Prediction of Dilution in Plasma Transferred Arc Hardfacing of Stainless Steel on Carbon Steel, Science Direct, Volume 16, Issue 1, pp.44-53.
Giridharan P.K, Murugan N. (2007). Effect of pulsed gas tungsten arc welding process parameters on pitting corrosion resistance of type 304L stainless steel welds, Corros J,63(5),pp.433–441.
Hsiao.Y.F, Tarng.Y.S and Huang.W.J. (2008). Optimization of Plasma Arc Welding Parameters by Using the Taguchi Method with the Grey Relational Analysis, Journal of Materials and Manufacturing Processes, 23, pp.51–58.
Montgomery DC, Design and analysis of experiments, 6th Ed. Wiley, New York, 2005.
336 K. Siva Prasad, Ch.Srinivasa Rao, D.Nageswara Rao
Plasma Welding: more accurate, better control at lower currents, Modern Application News, December 1999.
Siva.K, Muragan.N, Logesh.R. (2008). Optimization of weld bead geometry in Plasma transferred arc hardfacing austenitic stainless steel plates using genetic algorithm, Int J Adv Manuf Technol, Volume 41,Numbers 1-2, pp.24-30.
Sheng-Chai Chi, LI-Chang Hsu. (2001). A fuzzy Radial Basis Function Neural Network for Predicting Multiple Quality characteristics of Plasma Arc Welding, IEEE,0-7803-7078-3/01,pp.2807 -2812.
Zhang. D.K. and Niu.J.T. (2010). Application of Artificial Neural Network modeling to Plasma Arc Welding of Aluminum alloys, Journal of Advanced Metallurgical Sciences, Vol.13, No.1,pp.194-200.
K.Siva Prasad is an Assistant Professor of Department of Mechanical Engineering at Anil Neerukonda Institute of Technology & Sciences, Visakhapatnam, India. He received his Bachelors degree from Osmania University, India and Master Degree from JNTU, Hyderabad, India. He is also a part time scholar at Andhra University. He is a member of various professional bodies like ISTE, FPSI, ISHRAE etc. His area of research is micro welding processes.
Dr.Ch.Srinivasa Rao is an Associate Professor in the Mechanical Engineering Department at Andhra University, Visakhapatnam, India. He obtained his PhD degree from Andhra University, Visakhapatnam, India. He has published his research papers in various International Journals and conferences proceedings. He is a member of various professional bodies like ISTE, IE etc. His area of interest is manufacturing sciences, rapid prototyping and robotics.
Dr.D.Nageswara Rao is a Professor in the Mechanical Engineering Department at Andhra University, Visakhapatnam, India. He obtained his PhD degree from Indian Institute of Technology Delhi, India. He is the coordinator for Centre for Nanotechnology at Andhra University. He has successfully completed various projects sponsored by DST, UGC, AICTE, NRB etc. His area of research is manufacturing sciences and nanotechnology.
Peer Review: This article has been internationally peer-reviewed and accepted for publication
according to the guidelines given at the journal’s website.
*Corresponding author (Ahmad Sanusi Hassan). Tel/Fax: +6-04-6532835. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/337-353.pdf
337
International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
http://www.TuEngr.com, http://go.to/Research
Habitability Study on Low-Cost House Design of Modern and
Traditional Mid-rise House Units in the City of Mukalla, Yemen Anwar Ahmed Baeissaa, and Ahmad Sanusi Hassanb*
a Department of Architecture and Environmental Planning, Faculty of Engineering and Petroleum,
Hadhramout University of Science and Technology, YEMEN b School of Housing, Building and Planning, Universiti Sains Malaysia,11800 Penang, MALAYSIA A R T I C L E I N F O
A B S T RA C T
Article history: Received 06 April 2011 Received in revised form 24 June 2011 Accepted 25 June 2011 Available online 27 June 2011 Keywords: Habitability, House design, Low-cost houses, Traditional style
This study investigates the measurable factors which influence the residential level of satisfaction in low-cost house units in Mukalla, Yemen. The importance of this study is due to the development of this city that has been influenced by modern architecture since colonial period. It is the tradition in Mukalla that most population live in traditional (known as tower houses) and modern mid-rise houses. The work aims to examine the level of habitability of modern house design in comparison to the level of habitability of house design of the traditional houses. The result shows that levels of satisfaction of the respondents who live at traditional house units are generally higher than those in modern house units. The finding of the study indicates house design as an important factor that determines the level of residential satisfaction. This research contributes several proposals from the research findings considered for house design guideline for the local authority to improve quality of modern house layout units with reference to the traditional house design layout in the present and future development.
2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Some Rights Reserved.
International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies 2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. 2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies.
338 Anwar Ahmed Baeissa and Ahmad Sanusi Hassan
1. Introduction Allen (1987: 355-356) in Oxford Dictionary argued that a house is defined as “…a
building for human habitation.” It covers the “…dwelling of houses as a provision of shelter
or lodging.’ The United Nations (United Nations, 1977: 4) defines a house as not simply as
shelter but also as a mean of the creation of communities considering the functions a house
has to perform. By house design, it means the quality of the house in terms of the
organization and the allocation of space areas relative to the key functions that a household
requires which is space planning and function. Caudill (1978) noted that an adequate house
layout always takes care of both the current and the future needs; and such needs may be
evaluated on the basis of quality rather than cost, size, light and building that make up the
physical environment the residents interact with. Therefore, layout space in house design that
man creates should meet a kind of needs, and the design adequacy calls for the ability of the
designer to put all the required elements within a defined and clear relationships. Landau et
al. (1988: 1453) in Chambers English Dictionary defines the term habitable as ‘…appropriate,
proper, and fit’. Habitability therefore, can be defined as the state of being habitable,
appropriate, or proper. Habitability, however, is relative term. In the context of a house, its
habitability can be viewed in terms of its fulfilment to certain needs. Habitability in
appropriate term is said to exist when needs are being fulfilled, or there is a match between
what is needed and what is being supplied by a house, and inhabitability arises when there is a
mismatch between the two. Habitable house plays a vital role in fulfilling the key functions
that a household require. House plans must be set to measure the quality of house design that
may be achieved by using quality indicators allowing future or current house layout to be
evaluated based on quality rather than cost, site, size, light, and building that make up the
physical environment they interact with (Caudill, 1978). This article does not provide a new
idea but it is a social based house unit research topic which provides additional contribution
of the existing knowledge supported with social survey on the house unit.
2. Issues on House Design in the Case Study This habitability’s study tackles low-cost housing development in Mukalla, Yemen. In
particular, it will look at the problem of inhabitable living conditions due to inappropriate
house design as argued by UN-HABITAT (2002). This issue has always been
underestimated by both the architects and the house builders due to the influence of modern
*Corresponding author (Ahmad Sanusi Hassan). Tel/Fax: +6-04-6532835. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/337-353.pdf
339
styles as noted by Damluji (1992:10) frequently considered as the solution. There has been a
proposal by the United Nations (1977) that housing should be integrated with the functions of
the interior house design for a habitable living condition. This aspect is as important as the
quality of the materials that have been used towards its development. The public low-cost
housing programmes are undertaken by the federal governments with supervision and
monitoring under the Ministry of Housing and Local Government. The architects should
focus on house designs that are based on the traditional Yemeni houses. They further assert
that when designing houses for the habitation of the low-income groups, such a focus could
serve as a guiding policy towards appropriate house design. Also they suggest that strict
adherence to such a policy-guideline would certainly makes the finished houses not only
friendly to the environment but are also able to sustain the local needs and traditions. Benton
and Benton (1975:111) have mentioned the importance of this point. The purpose of this
study is to examine the level of residential satisfaction level and factors affecting in low-cost
housing in Mukalla, Yemen. Residential satisfaction reflects the degree to which individuals’
human needs are fulfilled. Therefore, it acts a guide to policy makers to monitor the
implementation of housing policies. Since no study of residential satisfaction level in low-
cost housing in Mukalla, Yemen. The study hopes to fill the gap in this area. The results of
the study will help in understanding of overall satisfaction level with low-cost housing built
by government and monitoring the implementation of housing policy in the country. The
relationships of theoretical factors are grouped into five components, namely dwelling units.
3. Methodology The methodology of this study is derived from the aim of this paper which is to examine
the level of habitability of modern house design in comparison to the level of habitability of
house design of the traditional houses. Following the ideas of Johnson and Christensen
(2000:136), these definitions have been identified as mentioned in the previous discussion on
habitability. The same factors have been used in the qualitative and the quantitative surveys.
The data obtained have been used in the qualitative and the quantitative analyses. The
adoption of the two analyses is congruent with Badar's (1982: 314-343) contention that it is
better to follow more than one method to get to the truth and to avoid biased data, such as the
respondents' bias. Finally, the control sample has been selected by the same method used
when selecting the practical sample (random/stratified/survey). Therefore, all the different
340 Anwar Ahmed Baeissa and Ahmad Sanusi Hassan
elements represent both the control and the practical samples with the same percentage. This
has been done in order to be able to compute the impact of factors under study which we
need. There are two types of analyses: qualitative and quantitative.
3.1 Measurable Scale According to Hanks (1977) in Collins English Dictionary, satisfaction is defined as the,
‘…act of satisfying; the state of being satisfied; the fulfilment of a desire; the pleasure
obtained from such fulfilment; a source of fulfilment…’ (1977: 1297).
The opposite of satisfaction is dissatisfaction, which means ‘…lack of satisfaction or
contentment’ (Allen, 1984: 212). According to the Oxford Dictionary, the concept of level of
satisfaction cannot be measured in absolute terms; instead, it is usually measured in a
continuum ranging from very satisfied to very dissatisfied, and that the level of satisfaction
varies in relation to several factors such as circumstances, time or between person-to-person
depending on each individual background. Residential level of satisfaction first is recognised
as important component of individuals' quality of life and second individuals' evaluation of
house design determine the way they respond to residential environment. Therefore, the
knowledge about factors that figure residential level of satisfaction is critical for
understanding of household moving decision process (Lu, 1999). Residential level of
satisfaction is based on the notion that residential satisfaction measures the difference
between households’ actual and desired house design layout and situations. They make their
decisions about residential conditions based on their needs and aspirations. Satisfaction with
their residential conditions indicates the absence of complaints as their needs meet their
aspirations. On the other hand, they are likely to feel dissatisfied if their house design does
not meet their residential needs and aspirations. Morris and Winter (1978) presented the idea
of ‘‘housing shortage’’ to conceptualise residential satisfaction. Their housing adequate
theory contends that if a household’s current housing meets the norms; the household is likely
to express a high level of satisfaction with housing needs.
4. House Design in Mukalla The architecture of Mukalla is dominated by white painted houses and buildings, (Figure
2). The architectural styles are a mixture of Arabic, Yemeni and Indian patterns. It is
characterized by unique architectural designs of the 18th and 19th centuries. The space
*Corresponding author (Ahmad Sanusi Hassan). Tel/Fax: +6-04-6532835. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/337-353.pdf
341
planning in the traditional houses in Mukalla has been moulded by the culture, values and
lifestyles of the Hadhrami people. In addition, the space planning has been influenced by
their attitude to give priority to privacy. At the same time they have emphasised their
preference for community intimacy, their needs for seasonal feasting and other cultural
activities. The study of the interior space is focused on the following factors:
a. Diwan, dining area and bedrooms
b. Bathrooms
c. Corridor and storage
d. Courtyard and balcony
e. Compositions of the rooms' layout
Figure1: View of Old Picture’s Part of Mukalla showing a typical traditional mid-rise houses
(right) and an example of a house facade (left).
a. Bathrooms
In a traditional house in Mukalla, usually the diwan is a space located in front of a house
and which is essentially for males and is separated from the private areas of the house which
visitors or strangers do not see. In this respect the location of the diwan plays an important
role in the layout of the house design unit as a whole. An analysis of the survey revealed that
this factor seems to have been recognized in the design of most of the houses. Some interior
spaces of a traditional house are generally not named by the conventional labels such as
diwan, dining room, but rather by the actual activities in the space at a particular time. The
only exceptions where the spaces are named permanently by their uses are the kitchen and the
toilets. There are, therefore, no permanent spaces with specific labels such as the living room,
the bedroom, the dining room, the hall or the study room, which are directly named after
342 Anwar Ahmed Baeissa and Ahmad Sanusi Hassan
certain activities as in the case of Western and modern houses. This reflects the multi-
functional nature and the non-specialised uses of the spaces in the modern houses in Mukalla
(Figure 2). This definition of space leads to inappropriate use of space and is consistent with
the inclinations towards inhabitable living conditions.
Figure 2: Example of Plan (left) and Axonometric (right showing the activities) of a Small-
Sized Interior Space in One Floor Level of One Unit Modern Apartments for Low-Income
Group.
The inhabitable space layout in the modern houses is basically found in houses in the
urban areas. The poor design and the construction seem have created physical problems on
the buildings themselves and some psychological problems on the residents. These seem to
have arisen from designs that have ignored the separation of males and the females, and also
not being sufficiently sensitive to the basis Islamic needs such as orientating the house to the
Kiblah. In addition, modern houses (apartments and flats) are considered to have many
disadvantages for local Mukalla people as such premises create a feeling of loneliness and
isolation. First the sizes are small. Second, the space functions in the modern apartments and
flats reflect the poor design and the distribution of the spaces, (Figure 2). There are rooms
that are used for various functions; for example, a diwan for women during the day time is
also transformed into a living room, a visitor room for many people during the day time.
Dining area is also transformed into a kitchen, and in a case a house unit with top floor
room/terrace is used by family members during the dining time. Bedrooms are transformed
into master’s bedroom, bedroom for males, and bedroom for females for family members
during the night.
Entrance door
Kitchen
Toilet
Hall
Visitor room
Bedroom
Living room
Entrance door
*Corresponding author (Ahmad Sanusi Hassan). Tel/Fax: +6-04-6532835. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/337-353.pdf
343
In contrast to the above, the life style in the traditional houses in Mukalla is unique and
exceptional. Indeed, the social functions behind the general aspect of the house design have
become private within the family. In a Mukalla traditional house, the other diwan is usually
located on the first floor. It is for accommodating visitors according to the gender (males and
females), (Figure 3). In the secluded diwan for women, the women do not need to cover
themselves and they are free from unforeseen visitors when they come in. Sometimes, the
rooms in the first floor are lent to the neighbours when they have important social activities.
The use of minimal furniture in a traditional house also helps to create a more flexible use of
the interior spaces. Bulky furniture not only cluster and break up interior spaces, they also
define and confine the spaces for certain uses only.
Figure 3: Floor Plans of a Traditional House Unit in Old Zone Scale 1/200 metres
Shows First Floor Level (right plan), Second Floor Level (middle plan) and Third Floor Level
(left plan).
The second floor, however, is to accommodate the elders and the relatives to live in.
Some rooms in this floor are designed for different functions, for instance a room which is
occupied by women in the day time as a diwan could be a bedroom at night for many people.
The third floor is entirely private as it places the bedroom for the head of the family and his
wife. Here the wife can receive, in private, her intimate friends. Children have their own
rooms on the third floor as well; they are not secluded and are free to move anywhere in the
house. Figure 4 depicts the first floor of a tradition house which is "socially" closed. It a
sense, it is only a semi- public space of the house. All visitors are not allowed to enter
Third floor Second floor First floor
344 Anwar Ahmed Baeissa and Ahmad Sanusi Hassan
directly. Only family members or close friends are allowed to enter the diwan (Figure 3 and
4). Strangers, if they are expected, can stay and wait for a while in the corridor, which is a
transition space. In the case of women visitors, the diwan is used but the men have to leave
the floor or even the house.
Figure 4: Diwan Interior Space (photo-left) and axonometric layout (right) of a Traditional
House Unit in Old Zone of Mukalla.
Figure 5: Illustrating the Absence of a Diwan in Low Income House Unit showing
Main Facade (top left), Axonometric Layout (top right) and Floor Plan (bottom) of Modern
One Unit Low-Income Modern Apartment.
Diwan
Visitor room
Dining room
Bathroom Kitchen
Visitor room
Dining room
Entrance Door
*Corresponding author (Ahmad Sanusi Hassan). Tel/Fax: +6-04-6532835. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/337-353.pdf
345
The second floor is reserved for the children and use during the day as the diwan for the
women of the family. The third floor is used by the parents. This floor keeps its original
function (bedroom) all day long (Figure 4). The foot bridge at the first floor which is used to
communicate with the next mid-rise house units is not used any more. The top floor
room/terrace which is an open spatial area is used for sleeping area during the hot summer
season. There is a traditional house in old zone which is more than 100 years old. It is one of
the best examples of a traditional house built in a traditional way with supporting walls in
freestones and flag in clay maintained by wooden grids and beams. In fact Old traditional
houses are very unique in their constructions as they are commonly adorned with purified
ornaments, come with special openings, built with terraces of parapet type and decorated with
wooden sculpture. This may be attributed to the division of the old buildings (previously
lodging a single family) into separate small apartments. In modern zones, the houses are
small due to economic grounds. One seemingly critical problem to a comfortable living life
style is that in all these small houses, (Figure 5), there is a significant absence of a diwan and
other spaces which are multifunctional in the traditional houses mentioned above.
b. Bathrooms
The design of modern houses does not cater a separate bathroom for the male and the
female members of the family. Instead, they have a common bathroom for both genders. This
is due to a dire shortage of space for any extra bathroom facilities. The lack of these facilities
is partly attributable to the apparent erosion of the religious values with respect to the social
interaction between a male and a female. In contrast to the above modern houses, the
traditional houses in the old zones contain their conventional sewage system that permits
them to possess flexible access to these facilities. That is, male and female members of the
family are assigned with separate bathrooms and toilets (Mukalla Master Plan, 1982).
c. Corridor and Storage
The corridor spaces and the space for the stairs in a modern house (apartments/flats) is
unsatisfactory by dimension and lighting and by the regular needs to move masses of goods.
Also, there is no storage and basement due to a limited area within the apartment. In a
traditional house, on the other hand, the main entrance provides sufficient space for the traffic
flow of the pedestrians in the house. Usually the entrance leads into a narrow passage to a
346 Anwar Ahmed Baeissa and Ahmad Sanusi Hassan
staircase which opens to a corridor space which in turn ushers the user to other spaces.
Therefore, the specific space layout in the traditional houses is sufficient. In particular, the
stairs are built around a huge pillar at the entrance or the main support of the house. In
addition, in the traditional houses there is sufficient storage space and a basement floor.
d. Courtyard and Balcony
Modern houses do not have any allocation of space for a courtyard and a balcony due to a
limited area and also due to the fact that their construction is from reinforced concrete. In
contrast, in a traditional house, the courtyards are very significant components as they provide
the ventilation and the cooling system. Costa (1995) mentioned that courtyards are built with
the intention of generating a constructive link between the external and internal environments.
Also they are designed to accommodate the different social activities such as the family
gatherings, a reception of guests and other related social occasions
e. Compositions of the Rooms' Layout
The arrangement of space between each pair of rooms and the rate of movement between
them play very important role in the locations and in the layout of the rooms. In modern
houses, the location of the rooms is very poorly laid-out due the limited space that is available
in them. However, in the traditional houses the location and the layout of house design
account the interior space elements like the doors, the windows, the interior walls, the floors,
and the ceilings. Usually, in a traditional house, the entrance leads into a narrow passage and
then to a staircase that leads to a corridor space which opens up to other spaces. The ground
floor is usually reserved for storage purposes while the first floor is allocated for social
activities. Such a composition of the space takes into account the emotions of the inhabitants
and accommodates their daily needs, wishes and ambitions. Therefore, in a traditional house
space layout is the central consideration as it accommodates the basic needs of the inhabitants
in organized and systematic ways which have been carefully thought out by the local master
builders.
5. Space Planning and Function This category has following factors: (a) Diwan (living room, visitor room and furniture
setting), (b) dining area, (c) bedrooms, (d) bathrooms, (c) corridor and storage, (e) courtyard
*Corresponding author (Ahmad Sanusi Hassan). Tel/Fax: +6-04-6532835. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/337-353.pdf
347
and the balcony, (f) compositions and layout of the rooms. In this qualitative study, the
criteria for evaluation are on qualitative analysis from checklist factors as discussed in the
literature review based on the researcher’s observation on the house design during the site’s
visit. The answer "Yes" represents as satisfactory and "No" as unsatisfactory. For example, if
the visitor’s room is satisfactory, the answer "Yes” will be marked as ‘x’, but when it is
unsatisfactory, the answer is "No" will be marked as ‘x’.
Table1: Items of Factors on House-Design.
Item
The Space planning and
function
Qualitative survey of
Modern Mukalla
Quantitative survey of Modern Mukalla
(% respondents)
Qualitative survey of Old Mukalla
Quantitative survey of Old Mukalla
(% respondents) Yes No Yes No
a
Diwan 55% 72% (a) living room x 53% x 70% (b) visitor room x 56% x 73% (c) furniture setting x 57% x 74%
b
Dining Area 42% 64% (a) Dining room x 40% x 62% (b) Kitchen x 42% x 65% (c) Top floor room/terrace
x 43% x 66%
c
Bedrooms 54% 67% (a) master bedroom x 52% x 65% (b) Bedroom for male x 55% x 68% (c) Bedroom for female x 56% x 69%
d
Bathroom 62% 70% (a) Bathroom for male x 60% x 69% (b) Bathroom for female x 64% x 71%
e
Corridor and Storage 45% 73% (a) Corridor Space x 42% x 71% (b) Stairs Space x 46% x 74% (c) Storage and basement floor
x 47% x 75%
f
Courtyard and Balcony
35% 46%
(a) Courtyard x 33% x 44% (b) Balcony x 37% x 48%
g The Composition of the room's layout
x 58% x 70%
N=17
Total
8
9
7
15
2
7
Total number of positive answers over
the total number of the items
8/17
9/17
351/7
15/17
2/17
462/7
Overall answers in percentages 47%
53%
50%
88%
12%
66%
348 Anwar Ahmed Baeissa and Ahmad Sanusi Hassan
On the other hand, the quantitative analysis is from the respondents’ answers (300
respondents) on their satisfaction level from questionnaires related to the same checklist
factors. The measurable scale is based on five rating scales of preferences in which each
respondent is required to identify by ticking only one answer ranging from 1 to 5 for each
question. These ranging scales are: No. 1: worst, No. 2: bad, No.3: no comment, No. 4: good
and No.5: best. According the Likert Scale (2006) an important distinction must be made
between a Likert scale and item (respondents’ answers from questions in the questionnaires).
The Likert scale is the sum of the responses (respondents’ answers) on Likert items
(questions). The total answers from each question are converted to obtain the mean average
ranging from 1 to 5 (x1 + x2 + x3 + …. xn divided by 5 = Mean Average). Finally, this mean
average of each question is converted to percentage scale to represent the percentage of the
respondents’ answers. The objective of the quantitative survey in this study is to identify the
factors of the level of satisfaction as perceived by the respondents represented with
percentages. The results of the qualitative and the quantitative analysis of the data are
presented in subsection of space planning and function, as in Table 1.
6. Results
6.1 Qualitative Analysis by Factors a. Diwan
i. The furniture setting in modern house design is unsatisfactory compared to the same items
in the traditional house due to the limited floor area for such purpose in the traditional
house design.
ii. The living and visitor rooms in the modern house design are found to be less satisfactory
than the same items in the traditional house design.
b. Dining area
i. The dining room and top floor room/ terrace in the modern house design are found to be
unsatisfactory compared to the similar items in the traditional house design due to a
limited floor area.
ii. The modern and the traditional house for kitchen have a similar level of satisfaction.
c. Bedrooms
*Corresponding author (Ahmad Sanusi Hassan). Tel/Fax: +6-04-6532835. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/337-353.pdf
349
i. The residents of the traditional houses find satisfaction with the house design of the
bedroom for the males and the females, while the residents of the modern houses find
these same items unsatisfactory. Both residents, however, find the house design of the
master’s bedroom as satisfactory.
d. Bathroom
i. In the modern house design, there is no allocation for separate bathroom for the male and
the female members of the family; hence the residents find this situation unsatisfactory. In
comparison, the residents of the traditional house design enjoy different allocation of
separate bathrooms for the males and the females.
e. Corridor and Storage
i. The residents of the modern houses find the allocation of space for the stairs satisfactory.
In comparison, the stairs in the traditional house design and the allocation of the basement
space are found unsatisfactory by its residents.
f. Courtyard and Balcony
i. No courtyard is found in the modern houses, and the residents find its absence
unsatisfactory. In comparison, the residents of the traditional house find enjoyment and
satisfaction in the availability and use of the courtyards there.
ii. The modern houses have balconies, and the residents find satisfaction in using them. The
traditional houses, however, do not have such similar balconies as they have regarded
them as a way of exposing the women to the areas outside the house which is counter to
the Islamic teachings. In fact the residents prefer the traditional premises to be without the
balconies, although some find its absence wanting.
g. Composition of the room's layout
i. On the whole, the residents regard the composition of the layout of the rooms in the
modern houses as unsatisfactory due to the limited built-up area in the modern house
designs. As a comparison, the residents of the traditional houses find satisfaction with the
nature of the layout and the organization of the interior spaces.
350 Anwar Ahmed Baeissa and Ahmad Sanusi Hassan
6.2 Qualitative Analysis by Category Table 1: shows that under the category of space planning and function, the average result
of Old Mukalla is 88%. Hence, it can be regarded that the residents there have considered the
factors within that category to be satisfactory. However, modern Mukalla has 47%. So,
relatively the residents seem to have felt that the traditional house designs on space planning
in the old zone have been considered as more habitable than those same factors in the modern
houses.
6.3 Quantitative Analysis by Factors For the quantitative analysis of the factors the relevant interpretation of the above
responses are as in (a) through (g) below:
a. The diwan
72% of the respondents from Old Mukalla are satisfied with the diwan (the living,
visitors’ rooms and furniture setting) as compared to merely 55% of the respondents from
Modern Mukalla find the diwan there satisfactory. In another words, generally the residents of
Modern Mukalla only slightly satisfied with the diwan of their houses.
b. The dining area
The analysis finds that 64% of the respondents from Old Mukalla perceive the dining
area facility in their houses to be satisfactory and that they are habitable. On the same factor,
the respondents from Modern Mukalla score only 42% suggesting they are not as satisfied as
their counterparts in Old Mukalla towards their dining area.
c. The bedrooms
With respect to the bedrooms, 67% of the respondents from Old Mukalla see their
bedrooms as satisfactory, while their counterparts in Modern Mukalla score only 54% on the
same factor suggesting that they find their bedrooms not as satisfactory as the respondents of
Old Mukalla find them.
d. The bathrooms
With a score of 70% on this factor, there is no doubt that the respondents of Old Mukalla
are more satisfied with their bathrooms than the respondents from Modern Mukalla who score
much less, which is 62%.
*Corresponding author (Ahmad Sanusi Hassan). Tel/Fax: +6-04-6532835. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/337-353.pdf
351
e. Corridor spaces and storage
On this factor, with a score of 73% the respondents of Old Mukalla clearly have
expressed much more satisfaction towards them than the respondents from Modern Mukalla
have as they score poorly with 45%.
f. Courtyard and balcony
With a score of 46% satisfactory answers for the courtyards and a score of only 35%
satisfactory answers for the balconies, the Old Mukalla residents are apparently more satisfied
with the courtyards than with the balconies. This is quite understandable as generally, the
traditional houses do not have balconies. The level of satisfaction on these two factors seems
to be the reverse in the case of the residents of Modern Mukalla. That is, with a satisfactory
score of 51% for the balconies as compared to a mere score of 19.5% for the courtyards, they
obviously have successfully expressed their displeasure and dissatisfaction towards the
absence of any courtyards in Modern Mukalla.
g. Composition of the house's layout
70% of the respondents of Old Mukalla have expressed satisfaction towards the
composition of the layout of spaces as compared to 58% of the respondents of Modern
Mukalla who have expressed similar satisfaction on the same factor. If these figures are any
positive indication of their perception, apparently the residents of Old Mukalla have perceived
their traditional houses to be more habitable with respect to this factor than their counterparts
have with their houses in Modern Mukalla.
7. Conclusion The perception of satisfaction on the nature of space planning of house layout, the
traditional houses of Old Mukalla were to be considered already have given more level of
satisfaction to its residents more than residents who live in Modern Mukalla. However,
relative to these perceptions, with a composite score of 88% from respondents’ answer for
Old Mukalla and 47% for Modern Mukalla. The residents of Modern Mukalla have expressed
dissatisfaction towards most of the factors. The main problems seem to have stemmed from
those aspects surrounding the feelings of discomfort and dissatisfaction due to limited space
areas, the absence of a diwan. In contrast, the residents of the traditional houses of Mukalla
352 Anwar Ahmed Baeissa and Ahmad Sanusi Hassan
seem to have expressed better views and more satisfied towards all the factors. On Old
Mukalla, from the qualitative survey high scores in the column of Table 1 for all the factors, it
is quite apparent that the respondents from Old Mukalla have rated highly all the factors. As
such these high average scores undoubtedly have served as expressions of much satisfaction
towards the house designs and the nature of the amenities there. In that light, within the ambit
of this study, the house designs in Old Mukalla can and do serve as references for the houses
in Yemen. The study has used the layout of the house design of the traditional houses of Old
Mukalla as the reference model.
At the end of the study, it is suggested here that the study has made the contributions
below with respect to people’s perception on the habitability of house design for the low
income group in Yemen in particular and some general ideas about habitability of house
design in the field of architecture in general. It has provided the definitions of the terms
house, designs and habitable within the ambit of the perception of the low-income group of
Yemenis.
8. Acknowledgements A very special thank you is due to Dr. Wijitbusaba Ann Marome for insightful
comments, helping clarify and improve the manuscript.
9. References Allen, R.E. (ed.). (1984). Oxford Dictionary. Oxford: Oxford University Press.
Allen, R.E. (ed.). (1987). The Oxford Dictionary of Current English. Oxford: Oxford University Press.
Badar, Ahmed. (1982). Ausul Al-Bahat Al-Elmi wa Manaheejh, (Methods of Scientific Research and Curriculum). (Arabic version). Al-Kuwait: Abdullah Hazami Agency Publications.
Benton, Tim and Benton, Charlotte. (1975). Form and Function. London: The Open University with Dennis Sharp.
Caudill, W. et al. (1978). Architecture and You: How to Experience and Enjoy Buildings. New York: Watson-Guptill Publications.
Damluji, S. S. (1991). A Yemen Architecture Sculptured in Mud and Stone. Reading: Garnet Publishing Limited.
*Corresponding author (Ahmad Sanusi Hassan). Tel/Fax: +6-04-6532835. E-mail addresses: [email protected]. 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/337-353.pdf
353
Damluji, S. S. (1992). The Valley of Mud Brick Architecture Shibam, Tharim and Wadi Hadhramout. London: Garnet Publishing.
Damluji, S. S. (2007). The Architecture of Yemen: From Yafi to Hadhramout. London: Laurence King Publishing Ltd.
Hanks, Patrick (ed.) (1977). Collins Dictionary of the English Language. London: William Collins Sons & Co.Ltd.
Landau, Sidney. I., et. al. (eds.). (1988). Chambers English Dictionary. Cambridge: Cambridge University Press.
Lu, M. (1999). Determinants of Residential Satisfaction: Ordered Regression Models, Growth and Change, 30, 264–287.
Morris, Earl and Winters, Mary. (1978). Housing, Family, and Society. New York. John Wiley & Sons, Inc.
Mukalla Master Plan (1982). Arab Institute for Design and Studies. Peoples Democratic Republic of Yemen. Beirut: 65 Emile Bustany Street.
UN-HABITAT (2002), United Nations Human Settlements Programme [Online], [Accessed 12 May 2006]. Available from World Wide: file:///E:/anwar/Desktop/Yemen.htm
United Nations, (1977). The Social Impact of Housing: Goals, Standards. Social. Indicators, and Population Participation. New York: Department of Economic and social Affairs.
Dr. Anwar Ahmed Baeissa is an assistant professor at Department of Architecture & Environmental Planning, Faculty of Engineering & Petroleum, Hadhramout University of Science & Technology (HUST), Yemen. He earned a Bachelor and a Master of Architecture (B. Arch & M. Arch) degrees in 1998 from the Odessa State Academy of Civil Engineering and Architecture, Ukraine, USSR. He worked from 1999-2003 as instructor at department of Architecture & Environmental, Planning and he had been awarded a PhD degree in 2009 from the University of Science Malaysia (USM), Penang, Malaysia. His research is focused on evaluations of space planning towards habitable house designs for low-income group.
Dr. Ahmad Sanusi bin Hassan is an associate professor in the Architecture Programme at the School of Housing, Building and Planning, University of Science Malaysia (USM), Penang, Malaysia. He earned a Bachelor and a Master of Architecture (B. Arch & M. Arch) degrees in 1993 and 1995 respectively from the University of Houston, Texas, USA. At the age of 29, he was awarded a PhD degree in 1998 from the University of Nottingham, United Kingdom. His research is focused on sustainable architecture and construction, and urban design. He is one of the nine regional writers, three of each from Asia, Africa and South America, who have been involved in the preparation of Guideline: Agenda 21 for Sustainable Construction in Developing Countries: A Discussion Document edited by Chrisna du Plessis, published by The International Council for Research and Innovation in Building and Construction (CIB), and United Nations Environment Programme International and Environmental Technology Centre (UNEP-IETC), which was launched at The Earth/World Summit, Johannesburg in September, 2002. At the university, he lectures in courses related to sustainable urban design, sustainable architecture and construction, Computer Aided Design (CAD), and computer movie animation. He has integrated all these specialisations into his research, teaching, consultation and publications.
Peer Review: This article has been internationally peer-reviewed and accepted for publication
according to the guidelines given at the journal’s website.
:: International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
http://TuEngr.com
Call-for-Papers:
ITJEMAST invites you to submit high quality papers for full peer-review and possible publication in areas pertaining to our scope including engineering, science, management and technology, especially interdisciplinary/cross-disciplinary/multidisciplinary subjects.
Next article continue on next page
*Corresponding author (H. Hamidifar). Tel/Fax: +982612231787. E-mail addresses: [email protected] . 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/355-364.pdf
355
International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
http://www.TuEngr.com, http://go.to/Research
Interrelationships between Characteristic Lengths of Local Scour
Hole Hossein Hamidifara*
a Department of Irrigation and Reclamation Engineering, University of Tehran, Karaj, Iran. A R T I C L E I N F O
A B S T RA C T
Article history: Received 12 May 2011 Received in revised form 21 June 2011 Accepted 28 June 2011 Available online 29 June 2011 Keywords: Local scour, Hydraulic structures, Characteristic lengths, Sediment, Sluice gate, Horizontal apron
This paper presents the results of an experimental study on local scour of noncohesive sediments downstream of a horizontal rigid apron. The experiments were carried out in a rectangular flume with 9m length, 0.5m width and 0.6m height which includes an alluvial test reach of 1.65m length and 0.2m depth at the end of the apron. Two types of uniform sediment with median diameters of 0.73mm and 1.85mm were used in the experiments. Time variations of the maximum scour depth was measured for some experiments. It was found that the scour hole does not reach the equilibrium state even after 48 hours. However, after the first 12 hours, the rate of extension of the maximum scour depth is found to be less than 0.001 cm/min. Although the scour profile seems to be three dimensional in nature, it was found that there is a geometrical similarity between the scour holes in all of the experiments. Variations of the characteristic lengths of the scour hole such as the maximum scour depth, dsm, the maximum extension of hole, L0, and the dune height, hd, are related to each other. Nondimensional graphs and formulas are suggested to determine the variation of these parameters in different conditions.
2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Some Rights Reserved.
International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies 2011 International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies.
356 Hossein Hamidifar
1. Introduction When jets impinge upon loose beds of granular material downstream of hydraulic
structures such as weirs or sluice gates, they can lead to significant local scour and may cause
stability problems of the structure. Constructing a rigid apron adjacent the structure is a
typical engineering solution to protect the structure. Over the last three decades, several
experimental studies have been conducted to investigate the local scour process caused by
submerged and unsubmerged two-dimensional (2D) and three-dimensional (3D) jets. Results
indicate that the maximum scour depth not only depends on the impinging flow velocity,
characteristics of bed material, but also the apron length and apron surface roughness.
The limit of the scour pattern can be considered to be an isoline of constant shear stress
with a value equivalent to the threshold bottom stress. However, estimating the threshold
shear stress of a certain material presents uncertainties.
An approach to characterize the response of the sediment to jet flow, in the case of non-
cohesive sediment, is to use the densimetric Froude number associated with a representative
diameter. The densimetric Froude number F0 is defined as U0/(gdiΔρ/ρ)0.5, where U0 is the jet
velocity at the nozzle, g the acceleration due to gravity, di a representative size of the bed
material, and Δρ is the difference between the density of the bed material ρs and the density of
the fluid ρ. From dimensional considerations, F0 is a measure of the ratio of the tractive force
acting on the bed particle to the submerged specific weight of the particle.
Due to the practical importance,local scour caused by the jets has been a topic of
continued interest to the researchers and the design engineers as well. Farhoudi and Smith
(1985) studied the development of scour holes downstream of a spillway due to hydraulic
jump over an apron. Ali and Lim (1986) conducted experimental investigations to study the
localized scour caused by two- and three-dimensional turbulent wall jets. Recently published
results indicate that the scour hole develops rapidly in the early stages and progresses towards
an asymptotic stage beyond which the scour profile does not change significantly with time
and reaches an equilibrium state (Balachandar et al., 2000; Kells et al., 2001; Lim and Yu,
2002; Sarkar and Dey, 2004; Dey and Sarkar, 2006; Alihosseini et al., 2008; Oliveto et al.,
2008, Sarathi et al., 2008, Hamidifar et al., 2010, 2011; Omid et al., 2009).
*Corresponding author (H. Hamidifar). Tel/Fax: +982612231787. E-mail addresses: [email protected] . 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/355-364.pdf
357
Dey and Westrich (2003) investigated the flow characteristics of submerged jets over an
apron and in an equilibrium scour hole in cohesive beds. Moghim et al. (2008) developed an
empirical equation by using regression analysis to predict the maximum scour depth
downstream of aprons. In a more recent study Khwairakpam and Mazumdar (2009) conducted
a review on local scour around hydraulic structures.
However, nowadays many criteria are proposed to determine dimensions of the scour
hole. The research reported in this paper focused on finding the interrelations between
characteristic lengths of local scour hole downstream of an apron.
2. Materials and Methods Experiments were carried out in a recirculating glass-sided flume in the central laboratory
of water researches in University of Tehran. The flume was 9m long (the test reach being 3 m
long), 0.5m wide and 0.6m deep. Water was continuously pumped from the downstream
reservoir into the upstream head tank with a maximum capacity of 25 l/s. A calibrated
rectangular sharp crested weir was used to measure the discharge.
Figure 1: Experimental setup.
A submerged horizontal jet was produced by flowing water through a sluice gate opening
equal to 2cm over an apron of 1m length followed by a 0.2m deep sediment bed container.
The initial bed slope was adjusted to zero for each run using a carriage system riding on the
358 Hossein Hamidifar
rails over the flume. At the downstream end, a tailgate allows the regulation of the flow depth
in the flume. The discharge Q, was set constant for each run and a constant tailwater depth
Tw, 10 times the gate opening Y1, was also set in order to satisfy the conditions of deeply
submerged horizontal jet.
3. Results and Discussion As soon as the water flowing from the sluice opening reached the erodible bed, the
movement of bed materials from the end of the rigid apron started and the geometry of the
scour hole started changing with time. The scour profiles at various times were marked on one
of the glass walls of the flume. It was observed that during the initial stage the rate of scouring
was very high. It then gradually tapered off as time elapsed. Ultimately the equilibrium stage
was reached when no movement of grains was observed at the location of maximum scour.
For each type of bed material, experimental runs have been undertaken for different
tailwater depths and for various discharges. Before starting a particular run, the initial bed
surface was leveled. To avoid the disturbance of the bed before regulating the tailwater depth
and discharge, the alluvial bed surface was covered with a Plexiglas plate with the same width
as the flume. After the desired conditions were established, the plate was removed gently
from the downstream.
Before starting the next run, the disturbed bed was leveled after dewatering and drying
the bed. The whole procedure was then repeated, and a new scour profile was obtained. The
scour profiles have been used to determine the characteristic lengths of the scour hole at the
equilibrium state.
Time variations of the maximum scour depth was measured for some experiments. It was
found that the scour hole does not reach the equilibrium state even after 48 hours. However,
after the first 12 hours, the rate of extension of the maximum scour depth is found to be less
than 0.05cmh-1.
From the scour profiles, the maximum scour depth dsm, the location of maximum scour
depth Xm, the maximum scour point L0, the maximum dune height hd and the location of
maximum height of the dune Xd for all the test runs has been measured. To obtain relationship
*Corresponding author (H. Hamidifar). Tel/Fax: +982612231787. E-mail addresses: [email protected] . 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/355-364.pdf
359
between the characteristic lengths of the scour hole, these parameters were plotted against the
dimensionless maximum scour depth.
Figure 2 shows the variation of the maximum dune height hd. It is observed from this
figure that the variations of these two parameters follow a linear trend which can be expressed
as Eq. (1):
84.8827.25050
−⎟⎟⎠
⎞⎜⎜⎝
⎛=
dd
dh smd R2=0.96 (1)
In Figure 3 variations of the maximum scour point L0 is plotted against the maximum
scour depth. It is clear that the variation trend is not linear and a quadratic equation as Eq. (2)
can fit the experimental data.
863.7839.1025.050
2
501
0 −⎟⎟⎠
⎞⎜⎜⎝
⎛+⎟⎟
⎠
⎞⎜⎜⎝
⎛−=
dd
dd
YL smsm R2=0.95 (2)
In Figure 4 the variations of the location of the maximum dune height Xd, is shown. By
examination of different parameter to nondimensionalize Xd, it was found that the gate
opening Y1 is more appropriate than the particle median size d50. So, a new dimensionless
equation is proposed as below to determine Xd when dsm is known.
51.10198.3043.050
2
501−⎟⎟
⎠
⎞⎜⎜⎝
⎛+⎟⎟
⎠
⎞⎜⎜⎝
⎛−=
dd
dd
YX smsmd R2=0.88 (3)
Variations of Xm, against dsm is plotted in Figure 5 where Xm is the location of the
maximum scour depth downstream of the apron. As figure 5, the gate opening Y1 was used to
nondimensionalize this parameter as shown in Eq. (4). However, using Y1 was not remedial to
cover scattering of the data as well as figure 5.
338.0417.0004.050
2
501−⎟⎟
⎠
⎞⎜⎜⎝
⎛+⎟⎟
⎠
⎞⎜⎜⎝
⎛−=
dd
dd
YX smsmm R2=0.74 (4)
360 Hossein Hamidifar
Figure 2: The relation between maximum scour depth and maximum dune height.
Figure 3: Variations of maximum length of the scour hole against maximum scour depth.
*Corresponding author (H. Hamidifar). Tel/Fax: +982612231787. E-mail addresses: [email protected] . 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/355-364.pdf
361
Figure 4: Relation between the location of the dune maximum heigth against dsm.
Figure 5: Variation of the location of maximum scour depth against dsm.
A comparison between the results of the present and previous studies is shown in Figure
(6). A dimensionless parameter, r, is defined as Eq. (5) to find the relative error between the
results. It is seen from Figure (6) that as the dimensionless parameter dsm/Y1 increases, the
relative error decreases and the results of the different studies come close to each other.
362 Hossein Hamidifar
However there is considerable scatter in data for small values of the dimensionless scour
depth.
( ) ( )( ) studypresentsm
udypreviousstsmstudypresentsm
Yd
YdYdr
1
11 −= (5)
Figure 6: comparison of the results of the present and previous studies.
4. Conclusion The interrelationships between different parameters of local scour hole downstream of a
rigid apron is studied experimentally. The experiments were conducted in the wide range of
tailwater depths and different flow discharges. Results showed that there are good
correlations between scour hole parameters. So, some experimental equations were presented
by using regression analysis. It was found that the maximum dune height, the maximum
extension of the scour hole, the maximum extension of the dune, the distance between end of
the apron and both the maximum scour depth and the maximum dune height will increase if
the maximum scour depth increases. These proposed criteria can help hydraulic structure
enginners to design structures more safely.
5. Acknowledgement A very special thank you is due to Associate Professor Dr. Chavalit Chaleerakthrakul for
insightful comments, helping clarify and improve the manuscript.
*Corresponding author (H. Hamidifar). Tel/Fax: +982612231787. E-mail addresses: [email protected] . 2011. International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies. Volume 2 No.3. ISSN 2228-9860. eISSN 1906-9642. Online Available at http://TuEngr.com/V02/355-364.pdf
363
6. References Ali, K.H.M. and S.Y. Lim, 1986. Local scour caused by submerged wall jets. Proceedings of
the Institute of Civil Engineers Part 2 (81):607–645.
Alihosseini, P., K. Ebrahimi, M. Sanei and M. Mashaal, 2008. Experimental investigation of temporal variation of scour profile downstream of submerged hydraulic jumps. Proceedings of the 7th Iranian Conference on Hydraulic. Nov. 11- 13. Sh. Abbaspour University. Tehran. Iran (in Farsi).
Balachandar, R., J. Kells, and R. Thiessen, 2000. The Effect of Tailwater Depth on the Dynamics of Local Scour. Canadaian Journal of Civil Engineering, Vol. 27, 138-150.
Dey, S. and A. Sarkar, 2006. Scour Downstream of an Apron due to Submerged Horizontal Jets. Journal of Hydraulic Engineering, Vol. 132, No. 3, 246-257.
Dey, S. and B. Westrich, 2003. Hydraulics of Submerged Jet Subject to Change in Cohesive Bed Geometry. Journal of Hydraulic Engineering, Vol. 129, No. 1, 42-53.
Farhoudi, J. and K. Smith, 1985. Local Scour Profiles Downstream of Hydraulic Jump. Journal of Hydraulic Research, Vol. 23, No. 4, 343-359.
Hamidifar, H., M.H. Omid, and M. Nasrabadi, 2010. Bed Scour Downstream of Sluice Gates. Journal of Water and Soil, Vol. 24(4), 728-736.
Hamidifar, H., M.H. Omid, and M. Nasrabadi, 2011. Scour downstream of a rough rigid apron. World Applied Science Journal, (Accepted).
Khwairakpam, P., and A. Mazumdar, 2009. Local scour around hydraulic structures. International Journal of Recent Trends in Engineering, 1(6), 59-61.
Kells, J. A., Balachandar, R., and K. P. Hagel, 2001. Effect of Grain Size on Local Channel Scour Below a Sluice Gate. Can. J. Civ. Eng, 28, 440–451.
Lim, S. and G. Yu, 2002. Scouring Downstream of Sluice Gate. First International Conference on Scour of Foundation, Texas Transportation Institute, Nov. 17-20, Texas A & M University, College Station, Texas, USA.
Moghim, M. N., Dorsangi, M. G. and M. Ghodsian, 2008. Prediction of maximum scour depth due to wall jets by using neural networks, 4th National Congress on Civil Engineering, Tehran, Iran. (in Persian)
Oliveto, G., V. Comuniello, and B. Onorati, 2008. Temporal development of local scour downstream of positive-step stilling basins. Proceedings of River Flows. Sep. 3-5. Izmir. Turkey. 1673-1678.
Omid, M. H., H. Hamidifar, and A. Reisi, 2009. Effect of tailwater depth on local scour downstream of an apron. Proceedings of 8th International Congress on Civil Engineering. May 11-13. Shiraz, Iran (in Persian).
364 Hossein Hamidifar
Sarathi, P., M.A.A. Faruque and R. Balachandar, 2008. Influence of tailwater depth, sediment size and densimetric Froude number on scour by submerged square wall jets. J. Hydra. Res. 46(2): 158-175.
Sarkar, A. and S. Dey, 2004. Review on local scour due to jets, International Journal of Sediment Research 19(3), pp. 210–238.
Peer Review: This article has been internationally peer-reviewed and accepted for publication
according to the guidelines given at the journal’s website.
H. Hamidifar is a PhD candidate of Water Structures at the Department of Irrigation and Reclamation Engineering at University of Tehran. He received his B.Sc. from Shiraz University. He continued his M.Sc. study at University of Tehran where he obtained his M.Sc. in Water Structures. He focuses on local scour (cohesive and non-cohesive sediments), Hydraulic jump and energy dissipaters.
:: International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies
http://TuEngr.com
Call-for-Papers:
ITJEMAST invites you to submit high quality papers for full peer-review and possible publication in areas pertaining to our scope including engineering, science, management and technology, especially interdisciplinary/cross-disciplinary/multidisciplinary subjects.
Next article continue on next page
More Research Publication Available at
http://TUENGR.COM
Submit your science research today.
:: International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies