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Chapter 10 Transportation and Assignment Models

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-1

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Learning ObjectivesStudents will be able to Structure special LP problems using the transportation and assignment models. Use the N.W. corner, VAM, MODI, and stepping-stone method. Solve facility location and other application problems with transportation methods. Solve assignment problems with the Hungarian (matrix reduction) methodTo accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-2

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Chapter Outline10.1 Introduction 10.2 Setting Up a Transportation Problem 10.2 Developing an Initial Solution:Northwest Corner Rule 10.4 Stepping-Stone Method: Finding a Least-Cost Solution 10.5 MODI Method 10.6 Vogels Approximation Method 10.7 Unbalanced Transportation ProblemsTo accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-3

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Chapter Outline continued10.8 Degeneracy in Transportation Problems 10.9 More Than One Optimal Solution 10.10 Maximization Transportation Problems 10.11 Unacceptable or Prohibited Routes 10.12 Facility Location Analysis 10.13 Approach of the Assignment Model 10.14 Unbalanced Assignment Models 10.15 Maximization Assignment ProblemsTo accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-4

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Specialized Problems Transportation Problem Distribution of items from several sources to several destinations. Supply capacities and destination requirements known.

Assignment Problem One-to-one assignment of people to jobs, etc.

Specialized algorithms save time!

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-5

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Importance of Special Purpose Algorithms Fewer, less complicated, computations than with simplex Less computer memory required Produce integer solutions

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-6

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Transportation ProblemDes Moines (100 units) capacity Cleveland (200 units) required

Albuquerque (300 units) required

Evansville (300 units) capacity

Boston (200 units) required

Ft. Lauderdale (300 units) capacity

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-7

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Transportation CostsTo (Destinations)

From (Sources)

Albuquerque Cleveland Boston Des Moines $5 $4 $3 Evansville Fort Lauderdale $8 $9 $4 $7 $3 $5

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-8

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Unit Shipping Cost:1Unit, Factory to WarehouseAlbuquerque Cleveland Boston Factory (A) (C) (B) Capacity 5 4 3 Des Moines (D) Evansville (E) Fort Lauderdale (F) Warehouse Req. 8 4 3

9

7

5

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-9

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Total Demand and Total SupplyAlbuquerque Boston (A) (B) Des Moines (D) Evansville (E) Fort Lauderdale (F) Warehouse Req. 300 200 200 Cleveland Factory (C) Capacity 100

300

300

700

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-10

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Transportation Table For Executive Furniture Corp.Albuquerque Boston (A) (B) Des Moines (D) Evansville (E) Fort Lauderdale (F) Warehouse Req. 300 5 4 Cleveland Factory (C) Capacity 3 100

8

4

3

300

9

7

5

300

200

200

700

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-11

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Initial Solution Using the Northwest Corner Rule Start in the upper left-hand cell and allocate units to shipping routes as follows: Exhaust the supply (factory capacity) of each row before moving down to the next row. Exhaust the demand (warehouse) requirements of each column before moving to the next column to the right. Check that all supply and demand requirements are met.

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-12

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Initial Solution North West Corner RuleAlbuquerque Boston (A) (B) Des Moines (D) Evansville (E) Fort Lauderdale (F) Warehouse Req. 300 5 100 8 4 3 4 Cleveland Factory (C) Capacity 3 100

200

100

300

9 100

7

200

5

300

200

200

700

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-13

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

The Stepping-Stone Method 1. Select any unused square to evaluate. 2. Begin at this square. Trace a closed path back to the original square via squares that are currently being used (only horizontal or vertical moves allowed). 3. Place + in unused square; alternate - and + on each corner square of the closed path. 4. Calculate improvement index: add together the unit cost figures found in each square containing a +; subtract the unit cost figure in each square containing a -. 5. Repeat steps 1 - 4 for each unused square.To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-14

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Stepping-Stone Method The Des Moines-toCleveland RouteAlbuquerque Boston (A) (B) Des Moines (D) Evansville (E) Fort Lauderdale (F) Warehouse Req. 300 100 5 4 Cleveland Factory (C) Capacity Start 3 100

-

+8 4 3 100 7 5

200

300

+9

+

100

200

300

200 200 700

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-15

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Stepping-Stone Method An Improved SolutionAlbuquerque Boston (A) (B) Des Moines (D) Evansville (E) Fort Lauderdale (F) Warehouse Req. 100 5 4 Cleveland Factory (C) Capacity 3 100

8 100 9 100 200

4

3

300

7

200

5

300

300

200

200

700

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-16

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Third and Final SolutionAlbuquerque Boston (A) (B) Des Moines (D) Evansville (E) Ft Lauderdale (F) Warehouse Req. 200 100 5 4 Cleveland Factory (C) Capacity 3 100

8 200 9

4 100 7

3

300

100

5

300

300

200

200

700

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-17

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

MODI Method: 5 Steps1. Compute the values for each row and column: set Ri + Kj = Cij for those squares currently used or occupied. 2. After writing all equations, set R1 = 0. 3. Solve the system of equations for Ri and Kj values. 4. Compute the improvement index for each unused square by the formula improvement index: Cij - Ri - Kj 5. Select the largest negative index and proceed to solve the problem as you did using the stepping-stone method. 10-18To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna 2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Vogels Approximation1. For each row/column of table, find difference between two lowest costs. (Opportunity cost) 2. Find greatest opportunity cost. 3. Assign as many units as possible to lowest cost square in row/column with greatest opportunity cost. 4. Eliminate row or column which has been completely satisfied. 4. Begin again, omitting eliminated rows/columns.To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-19

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Special Problems in Transportation Method Unbalanced Problem Demand Less than Supply Demand Greater than Supply

Degeneracy More Than One Optimal Solution

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-20

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Unbalanced Problem Demand Less than SupplyCustomer Dummy Customer Factory 1 2 Capacity 8 5 0 Factory 1 170 Factory 2 15 10 0

130

Factory 3

3

9

0

80

Customer Requirements

150

80

150

380

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-21

2003 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Unbalanced Problem Supply Less than DemandCustomer Customer Customer Factory 2 1 3 Capacity Factory 1 8 5 16 170

Factory 2

15

10

7

130

Dummy

0

0

0

80

Customer Requirements 150

80

150

380

To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna

10-22

2003 by Prentice Hall, Inc. Upper Saddle River