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A number of approaches to the aggregate planning problem have been proposed in the literature, yet experience suggests that industrial concerns seldom use these models in actual planning situations. This paper describes a modified random walk production-inventory heuristic for the problem which should appeal to managers on the basis of simplicity as well as efficiency. The proposed approach is contrasted with linear programming, parametric programming, and linear decision rule optimal and near optimal solutions for several well known production situations. The simple production switching heuristic produces schedules which exceed optimal schedules by only 1 to 2 percent of total production costs in all cases.planning, production/scheduling, inventory/production: production smoothing

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Efforts on a number of fronts are being made to enhance the usefulness of simulation as a tool for analysis. Graphical input, animation, automated program generation, model management utilities, and user interactive environments all address the issue of ease of use. Even with the current emphasis in this regard, simulation suffers from several shortcomings which preclude even greater application of the methodology. One of the more significant limitations is the dependence of simulation on statistical methodologies. Practically every phase of simulation analysis involves one or more statistical issues. And the fact of the matter is that many simulation practitioners have neither the statistical skills nor the access to qualified statisticians to effectively address these crucial issues.The obvious solution to this problem would be to have an expert statistician available during every simulation study to answer any questions concerning statistical issues. A more practical alternative is to make available an expert system which could function as a statistical advisor to simulation analysts. This option seems ideally suited for expert system techniques since it is welldefined and narrowly bounded and an appropriate body of statistical knowledge exists. The objective of this research was to develop such an expert statistical consultant. The system would be able to advise as well as perform appropriate computations for a variety of statistical issues including input data analysis, design of experiments, and output analysis. An overview of the proposed system is given and illustrations of the capabilities of the system are presented.

Simulation methods are effectively used to investigate design issues of a proposed flexible manufacturing system (FMS). Unfortunately, process design engineers rarely have the necessary expertise to take full advantage of simulation methodology. Process Planning Simulation (PPS) is a software package which allows engineers with virtually no simulation expertise to define FMS designs and generate the simulation code necessary to model designs of interest. PPS uses SIMAN to model process elements of an FMS, and IFPS to model the financial aspects of the system.