Ihsan Sabuncuoglu

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In this paper, we study the reactive scheduling problems in a stochastic manufacturing environment. Speci®cally, we test the several scheduling policies under machine breakdowns in a classical job shop system. In addition, we measure the e€ect of system size and type of work allocation (uniform and bottleneck) on the system performance. The performance of(More)
Assembly Line Balancing (ALB) is one of the important problems of production/operations management area. As small improvements in the performance of the system can lead to signi®cant monetary consequences, it is of utmost importance to develop practical solution procedures that yield high-quality design decisions with minimal computational requirements. Due(More)
Beam search is a heuristic method for solving optimization problems. It is an adaptation of the branch and bound method in which only some nodes are evaluated in the search tree. At any level, only the promising nodes are kept for further branching and remaining nodes are pruned off permanently. In this paper, the authors developed a beam search based(More)
In this study, we provide a new taxonomy of parameters of genetic algorithms (GA), structural and numerical parameters, and analyze the effect of numerical parameters on the performance of GA based simulation optimization applications with experimental design techniques. Appropriate levels of each parameter are proposed for a particular problem domain.(More)
In this paper, a new order reviewhelease (ORR) method is proposed for shop floor control systems. The proposed method utilizes both job due date and shop load information to improve the effectiveness of the ORR function in production systems. The performance of the new method is compared to those of a few well-known ORR methods under four experimental(More)
Scheduling is a decision-making process that is concerned with the allocation of limited resources to competing tasks (operations of jobs) over a time period with the goal of optimizing one or more objectives. In theory, the objective is usually to optimize some classical system performance measures such as makespan, tardiness/earliness and flowtime under(More)
Computer simulation is a widely used tool for analyzing many industrial and service systems. However, a major disadvantage of simulation is that the results are only estimates of the performance measures of interest, hence they need careful statistical analyses. Simulation studies are often classified as either terminating or non-terminating. One of the(More)
Beam search (BS) is used as a heuristic to solve various combinatorial optimization problems, ranging from scheduling to assembly line balancing. In this paper, we develop a backtracking and an exchange-of-information (EOI) procedure to enhance the traditional beam search method. The backtracking enables us to return to previous solution states in the(More)
Prescription fraud is a main problem that causes substantial monetary loss in health care systems. We aimed to develop a model for detecting cases of prescription fraud and test it on real world data from a large multi-center medical prescription database. Conventionally, prescription fraud detection is conducted on random samples by human experts. However,(More)