ECET 4550: A lternate Energy Fall 2011
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ECET 4550: Alternate Energy Fall 2011 Laboratory Topic: The Problem to be Solved “Statement of the Problem” Florian Misoc, 2010
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ECET 4550: A lternate Energy Fall 2011. Laboratory Topic : The Problem to be Solved “Statement of the Problem”. Chapter Objectives. Identifying and Representing the Client’s Objectives Measurable Quantities Setting Priorities Constrains: Limitations and Delimitations - PowerPoint PPT Presentation
Transcript of ECET 4550: A lternate Energy Fall 2011
Florian Misoc, 2010
ECET 4550: Alternate Energy
Fall 2011
Laboratory Topic:The Problem to be Solved
“Statement of the Problem”
Florian Misoc, 2010
Chapter Objectives
• Identifying and Representing the Client’s Objectives
• Measurable Quantities• Setting Priorities• Constrains: Limitations and Delimitations• Case Study and Examples
Florian Misoc, 2010
Introduction
• Problem Definition = the most important step in the design process
• Problem Definition: pre-design phase of design• Frame the problem => engineering terms• Focus on tasks 1 – 4:1. Clarify Objectives2. Establish Metrics for Objectives3. Identify Constrains4. Revise Client’s Problem Statement
Florian Misoc, 2010
Identifying and Representing the Client’s Objectives
• Client’s original problem statement:a. Initial statements: brief, general ideab. No hint on: intended market, shape of the
product, material to be used, etc.c. Initial statement has limitations: errors, bias,
imply solutionsd. Clarify what client wants: what potential users
need, e. Technological & marketing context
Florian Misoc, 2010
Identifying and Representing the Client’s Objectives
1. Errors: incorrect information, faulty and/or incomplete data, mistakes regarding the problem
2. Biases: presumptions about the situation, involving a person’s preference
3. Implied Solution: client’s best guess at solutions, frequently found in the original problem statement (related to bias)
Errors of the Design Process
Source: http://softwareindustrialization/CategoryView,category,Design.aspx
Errors of the Design Process
Source: http://softwareindustrialization/CategoryView,category,Design.aspx
Errors of the Design Process
Source: http://softwareindustrialization/CategoryView,category,Design.aspx
Errors of the Design Process
Source: http://softwareindustrialization/CategoryView,category,Design.aspx
Florian Misoc, 2010
Identifying and Representing the Client’s Objectives: Questions & Brainstorming
Two kinds of activity:a. Asking questions of the client/stakeholder, with
varying degree of interest in the problem/design
b. Brainstorming: group effort to generate, retain, and organize new ideas to solve the problem
Florian Misoc, 2010
Identifying and Representing the Client’s Objectives: Asking Questions
Questions to understand the scope of the project:a. What features/attributes you desire for …..?b. What do you want this …. to do?c. Are there already …. with similar attributes?
Ask also:i. What does it mean?ii. How are you going to do that?iii. Why do you want that?
Florian Misoc, 2010
Identifying and Representing the Client’s Objectives: Brainstorming
1. Focus on quantity: maxim quantity = quality. Great number of ideas = greater the chance of effective solution.
2. Withhold criticism: focus on extending or adding to ideas, reserve criticism for a later 'critical stage' of the process
3. Welcome unusual ideas: looking from new perspectives and suspending assumptions (may provide better solutions)
4. Combine and improve ideas: Good ideas = combinations of ideas: slogan "1+1=3”
Florian Misoc, 2010
Brainstorming: preliminary / start-up
Florian Misoc, 2010
Florian Misoc, 2010
Identifying and Representing the Client’s Objectives: Concept Definitions
A. Objective: something toward which effort is directed (an aim/end-of-action)
B. Constraint: restricted, compelled to avoid, compelled to perform
C. Function: fitness for use, “for which a thing is made-for”
D. Means: method used to attain and end
Florian Misoc, 2010
Client’s Objectives: Objective Tree
Florian Misoc, 2010
Measurable Quantities
Six Scale Types:1. Nominal Scales: distinguish among categories2. Partially Ordered Scales: hierarchies3. Ordinal Scales: rank / order4. Ratio Scales: percentage 5. Interval Scales: reference to a base-point6. Multidimensional Scale: compounds of other
scales
Florian Misoc, 2010
Pair-wise Comparison Chart (PCC)
Should be applied in constrained “top-down” fashion:
1) Objectives are compared when at the same level (in the objective tree)
2) Higher level objectives: compared first
• Only “top objectives” need to be ranked• “Low level objectives” are ranked ONLY for
complex systems
Florian Misoc, 2010
Weighted Objectives: American Beverage Company
Goals Environ.Benign
Distribute Taste Parentappeal
Market Brand Score
Environ.Benign
**** 0 0 0 0 0 0
Distribute 1 **** 1 1 1 0 4
Taste 1 0 **** 0 0 0 1
ParentAppeal
1 0 1 **** 0 0 2
Market 1 0 1 1 **** 0 3
Brand 1 1 1 1 1 **** 5
Florian Misoc, 2010
Weighted Objectives: National Beverage Company
Goals Environ.Benign
Distribute Taste Parentappeal
Market Brand Score
Environ.Benign
**** 1 1 1 1 1 5
Distribute 0 **** 0 0 1 0 1
Taste 0 1 **** 1 1 1 4
ParentAppeal
0 1 0 **** 1 1 3
Market 0 0 0 0 **** 0 0
Brand 0 1 0 0 1 **** 2
Florian Misoc, 2010
Pair-wise Comparison Chart (PCC)
• Pair-wise comparison chart for the “ladder design”
Goals Cost Portability Convenience Durability Score
Cost **** 0 0 1 1
Portability 1 **** 1 1 3
Convenience 1 0 **** 1 2
Durability 0 0 0 **** 0
Florian Misoc, 2010
Measuring Achievement of Objectives
• VDI 2225: Verband Deutscher Ingenieure / Association of German Engineers
• No Mathematical foundation for scaling or normalizing the PCC ranking
• PCC ranking = subjective preferences• Never weigh objectives: it could amplify the error
(no mathematical foundation)
Florian Misoc, 2010
Scale of Awarding PointsUse-Value-Analysis VDI-2225
Solution Value Points Perceived Value Points
Absolutely uselessVery inadequate
01
Unsatisfactory 0
WeakTolerable
23
Just tolerable 1
AdequateSatisfactory
45
Adequate 2
Good w. drawbacksGood
67
Good 3
Very goodExceeds requirements
Excellent
8910
Very good / Ideal 4
Florian Misoc, 2010
Metrics for Objectives
• Metric = repeatable: conducting the test/experiment (under identical conditions & restrains) would lead to identical results/outcomes
• Metric outcomes: understandable units of measure
• Metric assessment: unambiguous interpretation
Florian Misoc, 2010
Setting Priorities
“Lack of planning from your part does not translate in a priority from my part…”
Priority level: determined in the same fashion as awarding points
Priority # 1: SAFETY!!!(read the “oath of the engineer”)
Florian Misoc, 2010
Constrains: Limitations and Delimitations
• Limitations: are imposed by the available equipment, environmental conditions, time constrains, etc., and are out of experimenter’s control
• Delimitations: are imposed by the experimenter, as to restrict the purpose of said research
Florian Misoc, 2010
Case Study and Examples
Read and summarize:
1. Example 3.4.2: Establishing metrics for the beverage container
2. Example 3.6.1: Objectives and Constrains for the “Danbury Arm Support”
3. Example 3.6.2: Metrics for the Objectives “Danbury Arm Support”
Due: same time as assignment of Chapter 3
Florian Misoc, 2010
Assignment:
• Exercise # 3.1, page 77• Exercise # 3.2, page 77 & 78• Exercise # 3.5, page 78• Exercise 3.6, page 78: as it applies to your
particular group project
