Haruki Matsuura

Sequencing, dispatching and switching in a dynamic manufacturing environment

Abstract The problem of selection between sequencing and dispatching as a scheduling approach in a job-shop setting is investigated. Makespan performance using the two different approaches is compared through simulation experiments, under such dynamic manufacturing environments as machine breakdowns, specification changes and rush jobs. Based upon the experimental results, a new approach that switches sequencing to dispatching according to the manufacturing situation is proposed, to make the best use of both sequencing and dispatching approaches.

Comparison between simple infinite loading and loading considering a workload status under uncertainty in job operation times

Abstract Two loading approaches are compared, concerning the problem of selection between infinite loading and finite loading, which has been one of the fundamental themes in operations management. One is a loading approach that considers a workload status in setting planned lead times for the jobs. The other is an approach that does not take the workload status into account. Performances by these two approaches under uncertainty in job operation times were examined through two simulation study phases: a loading phase and a sequencing and executing phase. Results obtained show the superiority of loading considering a workload status, and also suggest that the superiority would be lost in real-life situations, where many disturbances occur.

Component part commonality and process flexibility effects on manufacturing performance

Abstract This paper deals with the problem of designing a flexible production system by simultaneously introducing both component part commonality and process flexibility. The basis for setting a goal is presented for component part standardization and for improving the production process through analysing the interrelationship between the component part commonality and process flexibility in terms of manufacturing performance in the fabrication/assembly process.

Concepts, practices and expectations of MRP, JIT and OPT in Finland and Japan

Abstract This paper aims at comparing Finnish and Japanese concepts and practices regarding manufacturing and operations management. It is seen that there are differences in applying MRP, JIT and OPT. A more detailed study reveals that these differences are partly due to the fact that these concepts are interpreted in different ways in these two countries.

Decision support system for production planning—concept and prototype

Abstract This paper deals with the problem of the decision support system for production planning from the viewpoint of two major functions: physical performance analysis and choice analysis. The first is make clear, through the physical performance analysis, the impact of decision variables on the system performance such as unfilled order rate for market demand, ratio of setup time, average inventory level of finished products and part items, and frequency of replanning. The second is to guide for selecting an alternative or setting the decision variables value, if management can, on the basis of the physical performance analysis results, provide a ranking, preference, or acceptable limits in terms of their contribution or importance to the production system. An example of the prototype DSS for the production planning is also presented from the above-mentioned viewpoint.

Hierarchical production planning system for a two-stage process

This paper deals with the problem of designing a hierarchical production planning system, where higher level decisions impose constraints on lower level decisions. This paper supports the choice of a production planning system for a two-stage process. First, analytical models clarify the relationship between production planning rules and the role of buffer inventory level in terms of manufacturing performance. Second, from the results of the analysis, a numerical example is presented on a production planning system designed under various management policies.

Setting planned lead times for multi-operation jobs

Abstract This paper deals with the problem of how to assign planned lead times for multi-operation jobs. The standpoint of the paper is that planned lead times should be determined, based upon a management policy concerning a tradeoff between work-in-process quantities in a shop and capacity requirements variations on a bottleneck machine. A method of determining a planned lead time for a multi-operation job is proposed, through analyzing average loading times in a shop and capacity requirements variations on a bottleneck machine. The lead time is determined on the basis of the jobs total operation time in a shop. Poisson job airival to a shop and periodic loading are assumed. The method is derived with Lagranges method of indeterminate coefficients. It can minimize capacity requirements variations on a bottleneck machine under a given average loading time in a shop.

Makespan comparison between resequencing and switching in a dynamic manufacturing environment

Abstract Makespan performance capabilities, using dispatching, fixed sequencing, resequencing and switching as a scheduling approach, are compared in a general job shop setting. Switching is defined as an approach that changes fixed sequencing to dispatching, considering the manufacturing status. Two stages of simulation experiments were conducted under several intensity levels of machine breakdown occurrences and rush job arrivals. The first experiment clarifies that resequencing is superior to fixed sequencing and that switching is superior to dispatching. The second experiment, comparison between resequencing and switching, indicates that switching can dominate resequencing with no short re-sequencing intervals under high disturbance intensity levels.

A comparison of centralized and decentralized control rules in push-type production ordering systems

Abstract This paper deals with the problem of designing an effective production ordering system to make as small production order variations and inventory level variations as possible, in which each production stage has a mutually different production ordering interval. System performance is evaluated, through a proposed analytical model, by making quantitative comparisons between the centralized and the decentralized system. General guidelines are presented for selection of an information feedback system.

Power generation scheduling by neural network

A new method for solving a power generation scheduling problem in an electric power system is presented. The objective is to determine the hourly start-up/ shut-down schedules of all generators so that forecasted hourly power demands per day may be met and total operating costs, the sum of setup and fuel costs for a given day, may be minimized. The problem may be formulated as a large-scale combinatorial optimization problem which includes 0-1 variables representing the start-up/shut-down of generators and continuous variables representing the power outputs. Determination of an optimalsolution within practical time limits is consequently difficult. Until now, the lagrangian relaxation method has been studied as it appeared to be the most practical method for obtaining an approximate solution to the problem. The efficiency of this method, however, depends on how the Lagrange multipliers are determined. Here, it is proposed that the Lagrange multipliers be estimated by utilizing the neural network and resul...