Tran Van Hoai 1

Applied Management ScienceIntroduction

Tran, Van HoaiFaculty of Computer Science & Engineering

HCMC University of Technology

2012-2013

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Jam jam jam

2012-2013

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…and still jam jam jam

2012-2013

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Ideas ?

• General solutions– to remove network of roads– to …destroy all vehicles– to open more roads

• to extend existing roads

– To reduce vehicles (or people)• To extend existing vehicles’ size

2010-2011

Beginning of human-beings

HCMC, Hanoi

LONG TERM

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Ideas

• Operational solutions– to modify intersection geometry

– to control traffic light(s)• static, dynamic (adaptive)

– to assign lanes for each vehicle type• routes assigned for each lane

– to enforce law/regulations on drivers

2010-2011

Road(s)

Control(s)

Vehicle(s)

SHORT TERM

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Challenge in proposed solutions

• Ideas to solve traffic jam are quite obvious• But how to solve is not easy2010-2011 Tran Van Hoai

SCIENTIFIC APPROACH

Modeling OptimizingAnalyzing Simulating

QUANTITATIVE RESULT

7

Definitions• Management science is the discipline that adapts the

scientific approach for problem solving to executive decision making in order to accomplish the goal of

“doing the best you can with what you’ve got”(Laurence & Pasternack)

• Operations research is an interdisciplinary branch of applied mathematics and formal science using mathematical modeling, statistical analysis, and mathematical optimization, … to arrive at optimal or near-optimal solutions to complex decision-making problems(wiki)

2010-2011 Tran Van Hoai

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More (historical) definitions• Scientific methods of providing executive departments

with a quantitative basis for decisions regarding operations under their control(Morse & Kimball – 1951)

• The use of techniques such as statistical inference and decision theory, mathematical programming, probabilistic models, network and computer science [to solve complex operational and strategic issues](US Army Pamphlet 600-3)

2010-2011

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Who need MS/OR ? (1)• Profit company

– To make money for stockholders

– To subject to responsibilities/restrictions• Delivering in reasonable time• Fair wage/working conditions for workers• Good products/services• …

2010-2011

Doing the best

with what you’vegot

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Who need MS/OR ? (2)• Nonprofit organization

– To provide minimum cost

– To subject to responsibilities/restrictions• Being responsible to oversees (donors,

subscribers,…)• Good service• …

2010-2011

Doing the best

with what you’vegot

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Who need MS/OR ? (3)• Government agencies

– To expect citizens,company to obey laws

– To subject to responsibilities/restrictions• Limitation of resources (capital, personnel,

technology,…)• …

2010-2011

Doing the best

with what you’vegot

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Who need MS/OR ? (4)• My wife:

to choose among n foods, each provides some of each of m nutrients– To find least expensive diet

– To subject to responsibilities/restrictions• Guaranteeing nutrients totally provided• …

2010-2011

Doing the best

with what you’vegot

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Some applications (not in Vietnam)

• Producing Hamburgers at Burger King– Linear programming

• Scheduling Crews at American Airlines– Integer linear programming

• Planning the Sony Advanced Traveler Information System– Shortest path network

• Planning Environmental Policy in Finland– Decision analysis

• Cooking at Mrs. Fields– Inventory modeling

• Designing Attractions at Disneyland– Queuing models

• Transporting Trash in New York City– Simulation model

2010-2011

What is crew scheduling ?

SGN

0730

HAN

0940

HAN

1340

DAD

1455

DAD

1655

SGN

1810

SGN

1510

DAD

1625

HAN

1010

SGN

1215

Aircraft 1

Aircraft 2DAD

1650

HAN

1800

-To assign pilots to flight legs -To manage pilot database, including

Personal information Timetable for training, vacation, day-off, …

-To monitor/report daily operations

Trivial schedule

SGN

0730

HAN

0940

HAN

1340

DAD

1455

DAD

1655

SGN

1810

SGN

1510

DAD

1625

HAN

1010

SGN

1215

Aircraft 1

Aircraft 2DAD

1650

HAN

1800

A A A

B B B

- Easy to make manually, but Having critical drawbacks …

Better schedule(pilot A) 4h + 2h + (pilot B) 2h55' + 25'= 9h20' idle for duty/ground out-base

PrimeSolution schedule

SGN

0730

HAN

0940

HAN

1340

DAD

1455

DAD

1655

SGN

1810

SGN

1510

DAD

1625

HAN

1010

SGN

1215

Aircraft 1

Aircraft 2DAD

1650

HAN

1800

A B A

A A B

- Much less duty/ground out-base time Less payment for idle time Backup pilots for disruptions

and MS/OR has more(pilot A) 30' + 30' + (pilot B) 1h55'

= 2h55' idle for duty/ground out-base

PrimeSolution fulfillment of rules

SGN

0730

HAN

0940

HAN

1340

DAD

1455

DAD

1655

SGN

1810

SGN

1510

DAD

1625

HAN

1010

SGN

1215

Aircraft 1

Aircraft 2DAD

1650

HAN

1800

A A A

B B B

Do not allow connection with rest time less than 30'

violates

SGN

0730

HAN

0940

HAN

1340

DAD

1455

DAD

1655

SGN

1810

SGN

1510

DAD

1625

HAN

1010

SGN

1215

Aircraft 1

Aircraft 2DAD

1650

HAN

1800

A B A

A A B

Key challenges – rules

Must comply with sets of rules – Issued by the government

(Cục hàng không dân dụng)

– Union/Contractual agreements– Operational rules

- Number of flying time per day- Number of duty time per week- Minimum resting time between consecutive flights- Minimum resting time for a week, month, year- …

- Maximum number of consecutive flights out-base - Maximum days for consecutive flights out-base- Bases for night resting- …

- Cannot check manually- Often changed

COMPLEX

Key challenges – cost structures

Crew cost only less than fuel cost– Payment for crew flying time– Payment for duty/ground out-base time

– Operational objectives

- Hotel costs- Per diem expenses- Dead-heading cost- …

- Maximize number of patterns (tour-of-duty)- Minimize number of patterns- Minimize number of out-base night rests- …

- Non-expert cannot model- Often changed

SPECIFICTRADEOFF

Key challenges – number of solutions

Business view point– Find low cost/high profit solution,

but do not violate any rules

Operational view point– Find robust (for disruption)

solution, but do not violate rules

- Good solution but violating rules- Valid solution but high cost- …

- Manual schedule is impossible- Only information technology and mathematics can help

HARDHUGE #

- Robust solution but violating rules- Valid solution but weak- …

Current schedule

Possible rule violation

MS/OR provides better schedule

61 duty/ground out-base nights

A better schedule

35 duty/ground out-base nights

No rule violation

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History

• Reading materials (given later)• Similar words:

– Operation research– Management science– Decision sciences– Quantitative methods

• Take (often) a quantitative view of decision making

– Industrial engineering

2010-2011

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MS/OR process

2010-2011

Problem Definition

Mathematical Modeling

Solution of the Model

Communication/Imple-mentation of Results