A comparative study of cell formation in cellular manufacturing systems

This paper analyses and evaluates six of the promising cell formation techniques by comparing and contrasting them in relation to the scores of efficiency indices of the exceptional elements and inner-cell densities, work-load balance, and under-utilizations in different scenarios. Accordingly, all six are more or less altered with proper extensions to realize a broader capability. Effectiveness of the suggested efficiency measures in the evaluation is also illustrated. Each technique seems to have a favourite operating area of its own considering a variety of factors. © 1994 Taylor & Francis Group, LLC

A cell formation algorithm: Hypergraph approximation - Cut tree

A new cell formation technique is presented and analyzed in this paper. The cell formation problem is defined using the hypergraph representation of the manufacturing systems. The proposed method approximates the hypergraph model by graphs so that the cuts are less affected by the approximation. Consequently, a Gomory-Hu cut tree of the graph approximation is obtained. The minimum cuts between all pairs of vertices are calculated easily by means of this tree, and a partition tree is produced. Our cell formation algorithm successively cuts the partition tree. The algorithm is subjected to an experimentation of randomly generated manufacturing situations. The algorithm is compared with other cell formation techniques as well. (C) 1998 Published by Elsevier Science B.V. All rights reserved

Semi-dynamic modelling of heterogeneous land combat

We propose a semi-dynamic approach to tactical level land combat modelling from the attacker's viewpoint. Our approach decomposes a battle between heterogeneous forces into stages and mini battles. For each mini battle in a stage, we use three models: a mathematical programming model for optimizing force allocations, a Lanchester simulation model for predicting whether or not the stage targets are reached under the allocations, and a model for weapon effectiveness update from one stage to the next. These models interact with each other within the framework of a decision support system to help the user with allocation decisions as well as prediction of force requirements to win the battle

Disassembly line balancing with limited supply and subassembly availability

Disassembly line balancing problem (DLBP) aims at finding a feasible assignment of disassembly tasks to workstations such that precedence relations among tasks are satisfied and some measure of effectiveness is optimized. We consider partial disassembly under limited supply of a single product as well as availability of its subassemblies. Hence, in satisfying the demand for revenue generating parts, both discarded products and available subassemblies can be utilized. We assume that part revenues and demand, task times and costs, inventory holding costs, and station opening costs are given. We propose two DLBP formulations. The first one maximizes the profit per disassembly cycle. The second formulation maximizes the profit over the whole planning horizon. Proposed formulations and computational results are presented

Vehicle routing with compartments under product incompatibility constraints [Ürün karişmama kisitlari altinda çok kompartimanli araç rotalama]

This study focuses on a distribution problem involving incompatible products which cannot be stored in a compartment of a vehicle. To satisfy different types of customer demand at minimum logistics cost, the products are stored in different compartments of fleet vehicles, which requires the problem to be modeled as a multiple-compartment vehicle routing problem (MCVRP). While there is an extensive literature on the vehicle routing problem (VRP) and its numerous variants, there are fewer research papers on the MCVRP. Firstly, a novel taxonomic framework for the VRP literature is proposed in this study. Secondly, new mathematical models are proposed for the basic MCVRP, together with its multiple-trip and split-delivery extensions, for obtaining exact solutions for small-size instances. Finally, heuristic algorithms are developed for larger instances of the three problem variants. To test the performance of our heuristics against optimum solutions for larger instances, a lower bounding scheme is also proposed. The results of the computational experiments are reported, indicating validity and a promising performance of an approach. © 2019, Faculty of Transport and Traffic Engineering. All rights reserved

Semi-dynamic modeling of tactical level land combat

We present a semi-dynamic approach to land combat modeling at tactical level. Our approach decomposes a battle into stages and mini battles. For each mini battle in each stage, we use three models: a mathematical programming model for optimizing force allocations, a Lanchester simulation model for predicting whether or not the stage targets are reached under the allocations, and a weapon effectiveness update model from one stage to the next. These models interact with each other within the framework of a decision support system to help the user with allocation decisions as well as prediction of force size and weapon requirements to win the battle

A constraint programming approach to a real-world workforce scheduling problem for multi-manned assembly lines with sequence-dependent setup times

For over five decades, researchers have presented various assembly line problems. Recently, assembly lines with multiple workers at each workstation have become very common in the literature. These lines are often found in the manufacturing of large vehicles, where workers at a workstation may perform their assigned tasks at the same time. Most research on multi-manned assembly lines focuses on balancing tasks and workers among workstations and scheduling tasks for workers. This study, however, concentrates on assigning tasks to workers already assigned to a specific workstation, rather than balancing the entire line. The problem was identified through an industrial case study at a large vehicle manufacturing company. The study presents two methods, one using mixed integer linear programming and the other using constraint programming, to minimise the number of workers required on a multi-manned assembly line with sequence-dependent setup times. The results of the computational experiments indicate that the constraint programming method performs better than the mixed integer linear programming method on several modified benchmark instances from the literature. The constraint programming model is also tested on the real-world scenario of our industrial case study and leads to significant improvements in the productivity of the workstations.</p