摘要:

To be truly effective, designers working in a distributed environment need to spend less effort on integration of their ideas and work and more on the actual design task. However, the distributed, sequential, and iterative nature of the process typically results in wasted resources and long lead times. The purpose of this research is the development of parallelism models for the configuration of design tasks to accomplish the most effective integration in a distributed environment. The analogy to parallel computing is described. Four dependence primitives are compared and a new one, codependence, is defined. Six types of integration function are defined. A new representation called IDM (iterative design model) is developed and explained relative to product design tasks. Advantages of IDM compared with previous approaches are also discussed.

ISSN:0740-817X    

DOI:10.1080/07408179808966433

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Tolerancing is one of the most important tasks in product and manufacturing process design. The allocation of design tolerances between the components of a mechanical assembly and manufacturing tolerances in the intermediate machining steps of component fabrication can significantly affect a product's quality and its robustness. This paper presents a methodology to maximize a product's robustness by appropriately allocating assembly and machining tolerances. The robust tolerance design problem is formulated as a mixed nonlinear optimization model. A simulated annealing algorithm is employed to solve the model and an example is presented to illustrate the methodology

ISSN:0740-817X    

DOI:10.1080/07408179808966434

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this paper, we consider a multiple-stage tandem production/inventory system producing a single product. Processing time at each stage is assumed to have a general stationary processing time distribution. The cost of holding work-in-process (WIP) inventory is different at each stage. Therefore, decisions on when to release work to the system as well as when to transfer WIP from one stage to another need to be made. We formulate this problem of release/production control as a Markov decision process. However, the optimal policy is rather complex, making its implementation impracticable in practice. We therefore investigate the performance of simple base stock policies. Our approach aggregates several stages into one and uses a simple approximation to compute ‘approximately optimal’ base stock levels. We present the results of a simulation study that tests the performance of our approximation in estimating the best base stock levels, and the performance of base stock policies as compared with the optimal policy.

ISSN:0740-817X    

DOI:10.1080/07408179808966435

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper presents an efficient method to evaluate performance of tree-structured assembly/disassembly (AD) systems with finite buffer capacity. The times to failure, the times to repair, and the processing times are assumed to be exponentially distributed. The method is based on an extension of a decomposition method originally applied to performance evaluation of transfer lines. The method decomposes aK-machine tree-structured AD system to a system ofK- 1 two-machine lines and then finds the processing rates, failure rates and repair rates of the decomposed system that make performance of the two systems close to each other. To determine those rates of the decomposed system, we derive 6(K- 1) equations based on interruption of flow, resumption of flow, and flow rate-idle time relations, and suggest two methods, which use the equations in different ways. Results from computational experiments show that the suggested decomposition methods give good estimates in a short time.

ISSN:0740-817X    

DOI:10.1080/07408179808966436

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Many assembly systems are required to hold minimal work-in-process inventories because of space or capital limitations. Unfortunately, in the presence of variable processing times, output from an assembly line may be severely restricted if no work-in-process inventory is held. Thus, assembly lines often should be designed to have minimal, but not zero, buffer capacity. In this paper we address the issue of how one should optimally deploy limited buffer capacity in unbalanced assembly systems, and we find that the answer is sometimes counterintuitive. We study simple asynchronous assembly systems with random processing times and develop simple heuristic rules that can be used to improve existing operations and to support line designers who are faced with increasingly rapid cycles of new product introduction. We apply these heuristics to several larger systems and discover that they perform quite well.

ISSN:0740-817X    

DOI:10.1080/07408179808966437

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this paper, we develop an analytical model of an order sortation system used in automated distribution centers. In such systems, groups of orders are delivered to a recirculating conveyor system where they are sorted into shipping lanes for final preparation and loaded onto waiting trucks. We develop a model of the sorting process, which incorporates the stochastic elements of these systems, to determine the relative merits of two common categories of sorting strategies found in industry: fixed priority schemes and the next available rule. Fixed priority schemes include such popular rules as “sort the largest (or smallest) orders first”. We show that in systems with little lane blocking, a rule which assigns the next available order to a shipping lane will outperform any fixed priority scheme in terms of sorting time and system throughput while in systems with significant lane blocking, the sorting rule has little impact.

ISSN:0740-817X    

DOI:10.1080/07408179808966438

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Cut order planning is the problem of planning the fabric cut for a set of apparel orders. A specified set of garments is ordered by the customer to be produced by a given date. Affiliated with this order is a set of garment sizes, and patterns for cutting each size. The fabric for cutting the order must be arranged on the cutting table in such a way as to minimize the cost of cutting the order. This plan must incorporate a partition of the pattern pieces to be arranged on top of the fabric layout. A mathematical model of the problem is developed and analyzed. On the basis of this analysis, solution approaches are developed that have been implemented on a desktop PC-based computer. Validated on representative industry problems, the approach is shown to be effective and versatile.

ISSN:0740-817X    

DOI:10.1080/07408179808966439

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The most common type of facility layout project is re-layout, which involves rearranging existing equipment in a facility. Project schedule development is an often overlooked yet critical portion of a facility re-layout project. When developing a re-layout project schedule, departments cannot be moved into their final locations until all previous occupants have moved. By incurring the cost of moving departments to temporary locations, it is possible to reduce the overall project duration. A two-criteria mixed-integer programming model is developed that finds the schedule minimizing department move costs subject to precedence constraints. An efficient algorithm uses this model to find all non-dominated time and cost solutions to the re-layout problem. Modifications to the basic model and algorithm handle resource constraints and turnaround space constraints. The algorithm and its modifications are demonstrated on an actual re-layout project.

ISSN:0740-817X    

DOI:10.1080/07408179808966440

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This note presents a simple method for transforming any two-station closed serial production system with finite buffers into an equivalent two-station open system by the appropriate removal of job carriers or buffers.

ISSN:0740-817X    

DOI:10.1080/07408179808966441

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0740-817X    

DOI:10.1080/07408179808966442

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor