- Contract Supplier Selection Software: This software is a by-product of a research paper which, in brief terms, analyses a manufacturer's decision of contracting with a long term or a short term supplier. The model assumes a stochastic market setting (demand and price are uncertain), where the short-term supplier offers lower setup/search cost and the long-term alternative offers a fixed price path for a substantial supplier development and search cost. The paper analyses the effect of demand and price uncertainties, drift rates, contract bounds, and supplier development cost relatives on the manufacturer's decision and the total cost. The solution technique used in this study is backward dynamic programming with contracting constraints.
I've coded the dynamic programming algorithm originally in Matlab- an excellent tool with the least development cost, but later switched to Visual Basic for versatility and to enable further use a stand alone tool. It works either by manually entering the input parameters or specifying an input file. This version is capable of solving only one instance of input parameters; if you wish to perform experimental runs, I could provide you with such version. Original code is available upon request. You can download the executable program and three sample input files via the below links.
Download:
 Contract Supplier Selection.exe
 Input Files.zip
- PDSDP Gams Model - Lagrangian Relaxation: This is a GAMS model for solving a three-echelon multi-commodity production-distribution system planning problem. This model and solution approach is based on:
Pirkul, H. and V. Jayaraman, Production, Transportation, and Distribution Planning in a Multi-Commodity Tri-echelon System, Transportation Science, 30(4), pp. 291-302 (1996)
You can download the archived model file and random input data generator excel worksheet. When the problem is set-up in excel worksheet and input data is parsed with the built-in VBScript macro, simply copy the corresponding areas into the model and run. The GAMS model is based on Lagrangian relaxation with sub-gradient optimization of the multipliers- try with different tolerance parameter levels.
Download: PDSDP-Gams-Lagrangian Relaxation.zip
...coming soon!
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