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Linear Programming. Example 5 Transportation Problem. Transportation Problem.
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Linear Programming Example 5 Transportation Problem
Transportation Problem • The transportation problem seeks to minimize the total shipping costs of transporting goods from m origins (each with a supply si) to n destinations (each with a demand dj), when the unit shipping cost from an origin, i, to a destination, j, is cij. • The network representation for a transportation problem with two sources and three destinations is given on the next slide.
Network Representation 1 d1 c11 1 c12 s1 c13 2 d2 c21 c22 2 s2 c23 3 d3 Sources Destinations
LP Formulation The LP formulation in terms of the amounts shipped from the origins to the destinations, xij , can be written as: Min cijxij i j s.t. xij<si for each origin i j xij = dj for each destination j i xij> 0 for all i and j
Example: Acme Block Co. • Acme Block Company has orders for 80 tons ofconcrete blocks at three suburban locationsas follows: Northwood -- 25 tons, Westwood -- 45 tons, and Eastwood -- 10 tons. • Acmehas two plants, each of whichcan produce 50 tons per week. • Delivery cost per ton from each plant to each suburban location is shown on the next slide. How should end of week shipments be made to filltheabove orders?
Delivery Cost • Delivery Cost Per Ton NorthwoodWestwoodEastwood Plant 1 24 30 40 Plant 2 30 40 42
LP Model Decision Variable X11: Tons of Concrete shipped from Plan 1 to Northwood X12: Tons of Concrete shipped from Plan 1 to Westwood X13: Tons of Concrete shipped from Plan 1 to Eastwood X21: Tons of Concrete shipped from Plan 2 to Northwood X22: Tons of Concrete shipped from Plan 2 to Westwood X13: Tons of Concrete shipped from Plan 2 to Eastwood Objective Function Min. 24X11+30X12+40X13+30X21+40X22+42X23
LP Model Constraints X11 + X12 +X13 <= 50 Plant 1 X21 + X22 + X23 <= 50 Plant 2 X11+X21 = 25 Northwood X12+X22 = 45 Westwood X13+X23 = 10 Eastwood Non-Negativity X11, X12, X13, X21, X22, X23 >=0
Solution • Optimal Solution FromToAmountCost Plant 1 Northwood 5 120 Plant 1 Westwood 45 1,350 Plant 2 Northwood 20 600 Plant 2 Eastwood 10 420 Total Cost = $2,490
Sensitivity Report • Partial Sensitivity Report (first half)
Sensitivity Report • Partial Sensitivity Report (second half)