摘要:

In the past few years researchers have given considerable attention to various aspects of lot-sizing for single-stage and multi-stage systems in material requirements planning (MRP). Numerous models have been developed and tested on problems with finite horizons and deterministic time-varying demand. A real production system is, however, so complex that no model can capture all the elements under consideration. Instead of the static horizon commonly assumed by researchers, real planning is usually carried out on rolling horizons with different lengths. Such performance measures may include minimization of the total cost, inventory level, and schedule instability caused by rolling horizon and the number of setups. For large and complex product structures, the conventional approach is to apply a single-stage lot-sizing rule once to every stage of the multi-stage system. The Wagner–Whitin (WW) algorithm does provide a solution to this problem, but the length of the necessary calculations precludes its use in practice. As a result, many researchers have proposed numerous other lot-sizing procedures. The purpose of this paper is to examine the performance of various multi-stage lot-sizing procedures under rolling horizon environment using simulation. Cost and schedule instability were used as the performance criteria and product structure, demand variabillity, cost structure and planning horizon were considered as independent variables. It has been shown that Silver–Meal (SM) procedure outperforms other procedures such as WW and incremental approach (ICA) in most of the cases. The performance of ICA and SM are better than their respective counterparts Gaither’s rule (GA) and modified Silver-Meal (MSM). The results also indicate that there are differences in the performance of various lot-sizing procedures when applied to two different product structures.

ISSN:0020-7543    

DOI:10.1080/00207543.1992.9728451

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In this paper we address a layout problem in flexible manufacturing systems (FMSs). A layout type that has been extensively implemented in FMSs is the single row machine layout. In such a configuration machines are arranged along a straight track with a material handling device moving jobs from one machine to another. The single row layout problem (SRLP) deals with the optimal arrangement of the machines for the above configuration. We propose a simulated annealing (SA) heuristic for the solution of SRLP. Extensive computational results, and ways to improve the performance of the SA algorithm through parameter fine-tuning procedures, are reported.

ISSN:0020-7543    

DOI:10.1080/00207543.1992.9728452

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An important element in the successful operation of flexible manufacturing systems (FMS) is the management of the tooling component. This paper reports on one aspect of tool management for FMS operations. Four tool allocation and scheduling strategies are compared in the presence of three part selection rules through a simulation study of a five-machine FMS with an automated tool handling system. The tool allocation strategies are similar to those used in industry while the part selection rules are synthesized from the literature on FMS scheduling under tooling constraints. The use of different tooling strategies produces significantly different outcomes in FMS performance.

ISSN:0020-7543    

DOI:10.1080/00207543.1992.9728453

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Frequent production requirements are linked to effective and profitable strategies for the management of queues, e.g. input buffers of machining centres and selection of rough workpieces from central storage. As a matter of fact, management policy performances must be evaluated by focusing not only on induced queue lengths or customer waiting times, but also on the future composition of the queues themselves, this being a consequence of the dispatching rule adopted. The question acquires further importance when flexible environments and buffer capacity constraints are considered. The aim of the present study is to illustrate an analytical procedure, based on the Markov chains theory, able to forecast the composition of buffers starting from any initial configuration. Attention is given to the buffer behaviour during the transient period and the steady state: results are offered for sequential and prioritized dispatching of items, together with application examples derived from common industrial situations. In the final sections, the possible extension of the procedure is considered and outlined with regard to particular management rules, thus introducing a further development of the present research.

ISSN:0020-7543    

DOI:10.1080/00207543.1992.9728454

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper describes the results of an experimental study on the effectiveness of cryogenically treated high speed steel (HSS) drills in drilling Hastelloy B and stainless steel work materials. The drills, 6·35 and 5·41 mm in diameter, were cooled at controlled rates in liquid nitrogen for a specific time period. Drilling was conducted at two cutting speeds for each work material at a fixed feedrate. Force and torque signals were collected through an on-line data acquisition system and subsequently analysed for emitted force, torque, power density spectrum and acoustic emission signal. Results indicate significant improvements in tool life of treated drills.

ISSN:0020-7543    

DOI:10.1080/00207543.1992.9728455

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A simple heuristic is proposed for multi-level lot-sizing problems where there is a bottleneck. Previous methods to solve this problem have formulated the problem as an integer programming problem and solved the problem using a Lagrangian relaxation embedded within the branch and bound procedure. In this paper we suggest that items to be produced can be grouped into two types and a simple but efficient heuristic can be used to determine the production quantities required. A program was developed to compute production levels and was found to require only a small fraction of the computer time required by the full integer programming approach, and to produce solutions of reasonable quality. The heuristic is simple to implement.

ISSN:0020-7543    

DOI:10.1080/00207543.1992.9728456

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The diffusion of flexible manufacturing systems (FMS) has not only invigorated production systems, but has also given considerable impetus to relevant analytical fields like scheduling theory and adaptive controls. The classical concepts and models may not be adequate to address the issues pertaining to FMS and they may have to be either modified or replaced. One of the important issues in this regard is the performance measures for these systems. These measures are needed for economic appraisals and for system design. Two such existing measures, flexibility and reliability, are re-examined in this paper. A new performance measure, producibility, is introduced here, which is defined as the extent to which a system fulfils its purpose. Appropriate mathematical models are developed to compute this measure for a system. Individual and combined effects of flexibility and reliability on a multi-component, multi-product system are analysed under the framework of producibility.

ISSN:0020-7543    

DOI:10.1080/00207543.1992.9728457

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper presents a neural network approach for machine fault diagnosis. Specifically, two tasks are explained and discussed: (1) a neural network-based machine fault diagnosis model is developed using the back propagation (BP) learning paradigm; (2) network training efficiency is studied by varying the learning rate and learning momentum of the activation function. The results are presented and discussed.

ISSN:0020-7543    

DOI:10.1080/00207543.1992.9728458

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In this paper two approaches to the automatic pairwise clustering of two-dimensional shapes for press tool design are discussed. The first is based on extracting the edge information in the form of edge arrays, which are manipulated to obtain the optimum pairing; while the second applies the non-deterministic concepts of genetic algorithms. The results of applying both approaches are also presented.

ISSN:0020-7543    

DOI:10.1080/00207543.1992.9728459

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

As a first step we develop an interactive simulation-based planning method for campaign production. Then the efficiencies of some lot-sizing methods for this type of production are analysed. A campaign is a set of products that must be manufactured in a certain sequence. Realistic problems include multistage–multiproduct-situations with arborescent structures. With such assumptions simulation studies are performed to show that heuristics developed for the non- time-phased production are not suitable for the time-phased production. Based on simulation results recommendations are made for the use of certain heuristics to examine situations with known data constellations. These recommendations are embedded in the interactive planning process called the ICOP-method.

ISSN:0020-7543    

DOI:10.1080/00207543.1992.9728460

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor