Jens Moberg Rygaard

A heuristic algorithm for a dial-a-ride problem with time windows, multiple capacities, and multiple objectives

The paper describes a system for the solution of a static dial-a-ride routing and scheduling problem with time windows (DARPTW). The problem statement and initialization of the development project was made by the Copenhagen Fire-Fighting Service (CFFS). The CFFS needed a new system for scheduling elderly and disabled persons, involving about 50.000 requests per year. The problem is characterized by, among other things, multiple capacities and multiple objectives. The capacities refer to the fact that a vehicle may be equipped with e.g. normal seats, children seats or wheel chair places. The objectives relate to a number of concerns such as e.g. short driving time, high vehicle utilization or low costs. A solution algorithm REBUS based on an insertion heuristics was developed. The algorithm permits in a flexible way weighting of the various goals such that the solution reflects the users preferences. The algorithm is implemented in a dynamic environment intended for on-line scheduling. Thus, a new request for service is treated in less than 1 second, permitting an interactive user interface.

OPTIMAL SCHEDULING OF COPRODUCTION WITH A STORAGE

Abstract The problem considered concerns the optimal scheduling of a system with combined heat and power (CHP) units and a heat storage. The purpose of the heat storage is to permit a partial decoupling of the variations in the demand for heat and electrical power. The problem of optimal scheduling is formulated as that of minimizing the total costs over the planning period. The heat demand from the district heating system and the shadow prices for the electrical power system are taken as externally given parameters. The resulting model is solved by dynamic programming. Implementation details and examples of result of the optimization are given.

Optimal Pallet Capacity For A FMS

The model formulation of the optimization problem describes the determination of the optimal number of pallets of each pallet type that should circulate in a flexible manufacturing system (FMS). Besides the pallet numbers, it considers a given configuration of the FMS, i. e. all other pieces of the equipment have already been determined. Optimization is done under consideration of a given part mix and a maximum throughput time.

A DECISION SUPPORT SYSTEM FOR DETERMINING MULTIPRODUCT OPTIMAL BATCH SIZES WITH IN-PROCESS INVENTORIES AND MULTIWORK CENTERS

This paper reports the development of a decision support system (DSS) to determine optimal batch sizes to situations where a range of products is made to stock and where products are manufactured in a production shop consisting of a number of work centers of functionally grouped machines. Numerical experiences are reported.

A Decision Support System for Determining Multiproduct Optimal Batch Sizes with In-process Inventories and Multiwork Centers

Abstract This paper reports the development of a decision support system (DSS) to determine optimal batch sizes to situations where a range of products is made to stock and where products are manufactured in a production shop consisting of a number of work centers of functionally grouped machines. Numerical experiences are reported.