摘要:

An automated Guided Vehicle (AGV) System with a limited number of vehicles cannot perform all of the transportation requests on demand. When a capacitated AGV system is used, then it is possible for the material handling system to become the bottleneck. There are many factors that affect the efficiency of an AGV system including how vehicles are routed and schedules. This paper presents a new dynamic approach to AGV routing. Simulation is used to study the effectiveness of this approach.

ISSN:0020-7543    

DOI:10.1080/00207549508945352

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper presents an integer programming model for existing FMS users to select the most cost effective set of parts to run simultaneously on an FMS during a specified production horizon. Two heuristic solution algorithms are developed by dividing the part-selection procedure in two stages. One stage deals strictly with the limitations on machining time, storage capacity, and AGV time. For the other stage, three different stages are used to choose a set of pan solely based on tooling and fixture constraints. The best algorithm-strategy combination has been identified and proved to be very efficient in finding optimal or near optimal solutions.

ISSN:0020-7543    

DOI:10.1080/00207549508904838

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The problem of scheduling a single batch processing machine with incompatible job families was studied, where jobs of different families cannot be processed together in the same batch. First static problems where all jobs are available simultaneously were considered and showed that for a regular performance measure there will be no unnecessary partial batches. This allowed us to develop efficient optimal algorithms to minimize makespan(Cmax), maximum lateness(Lmax)and total weighted completion time and apply some of these results to problems with parallel identical batch processing machines. Then problems withdynamic job arrivals were considered and an efficient optimal algorithm for minimizingCmaxand several heuristics to minimizeLmaxwere provided. Computational experiments showed that the heuristics developed for the latter problem consistently improve on dispatching solutions in very reasonable CPU times.

ISSN:0020-7543    

DOI:10.1080/00207549508904839

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Process planning for the manufacture of free surfaces is mainly concerned with determination of machining configuration. In this paper, we investigate the machining configuration problem stated as: For a given surface model, find (1) The minimum number of control axes, (2) The minimum range of the rotational axes, and (3) The workpart setup orientation. In deriving the solution algorithm, we ensured implementability by casting the problem into an algebraic domain. Using a digitized visibility map, called thebinary spherical map, the machining configuration problem can be solved in a unified fashion without falling into numerical complexity. The solution algorithms are implemented and validated via computer simulations, indicating they can be implemented on the CAD/CAM system as a process planner.

ISSN:0020-7543    

DOI:10.1080/00207549508904841

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The design of cellular systems is a complex, multi-criteria and multi-step process which can have significant implications for the entire organization. Most research in this area focuses on the formation of pan families and associated machine groups, one step in the cell design process. Numerous quantitative techniques have been developed to address this part-family/machine group formation problem. Existing approaches include math programming, algorithms for matrix diagonalization, the application of network modelling and the use of similarity coefficients. These mathematically-oriented techniques can handle a relatively limited set of quantitative objectives and. in addition, require many simplifying assumptions. For this reason, the solutions generated by these techniques are of limited usefulness in actual cell design.This paper proposes an expert system approach to cell system design. The starting point for the expert system is the initial solution generated by traditional mathematical techniques. Based on a flexible set of user-driven quantitative and qualitative factors, the expert system evaluates these preliminary solutions for feasibility and quality. If the solutions are not satisfactory (infeasible or of low quality), the system suggests modifications.

ISSN:0020-7543    

DOI:10.1080/00207549508904842

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper presents a critical evaluation of several widely used manufacturing simulators: WITNESS, SIMFACTORY 11·5. ProModelPC and XCELL +. Following a review of research into simulation software evaluation, an evaluation and comparison of the above simulators is performed on the basis of a case study. The main purpose of this evaluation was to discover the suitability of certain types of simulators for particular purposes.

ISSN:0020-7543    

DOI:10.1080/00207549508904843

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper considers the number of defective items in a lot to be a random variable and derives a modified (s, Q) model with stochastic demand and constant lead time. The paper develops explicit results for the case of exponential and uniform demand during lead time when the number of defective items in a lot follows a binomial process. It also investigates the effect of lower setup costs on the operating characteristics of the model. A numerical example is given and sensitivity analysis is performed.

ISSN:0020-7543    

DOI:10.1080/00207549508904844

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Industrial experience has shown that it is virtually impossible to implement a large-scale flexible manufacturing system (FMS) without using the group technology manufacturing concept. However, grouping machines into product cells can limit the FMS flexibility. Thus when the production cells are not completely disjoint, problems under multi-cell flexible manufacturing systems (MCFMS) can be caused by changes in job mix and demand which lead to a workload imbalance both between cells and between machine centres within the same cell. The problems can be mitigated and shop performance improved by transferring workloads from a congested machine centre in one cell to an alternative, less congested machine centre in another cell. Such inter-cell workload transfer results in a hybrid MCFMS which is a cross between a parts similarity-based MCFMS and a process similarity-based MCFMS. Results of a simulation study carried out by the author show that inter-cell workload transfer is very effective in improving shop performance. This paper briefly describes the simulation study and discusses the implications of its results for the design and operation of FMSs. The operational viability, and economic feasibility of hybrid MCFMSs are also discussed in the paper.

ISSN:0020-7543    

DOI:10.1080/00207549508904845

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Effective management of loading and work flow is becoming increasingly important in manufacturing. However, research has not addressed the associated dynamic internal performance issues as effectively as possible. This paper investigates an integrated approach to input and shop floor control under conditions of controlled delivery performance. Several new mechanisms are developed, including a method of dynamically adjusting buffer sizes based on system loads. Lead time and several measures related to the level and distribution of work in the system are used to evaluate performance. Results show that performance can be improved by taking loading and work flow issues into consideration when input release, dispatching and buffer space decisions are being made.

ISSN:0020-7543    

DOI:10.1080/00207549508904846

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The properties of a first-order, constant variance, dynamic linear model when monitoring ani.i.d.process are used to develop a framework for monitoring processes under startup conditions. Under stationary conditions, the statistic used for updating the estimate of the posterior mean of the process is just the exponentially weighted moving average (EWMA) control chart statistic. As such, an adaptation of the EWMA chart, referred to within as a dynamicEWMA chart, is proposed for monitoring short production runs. The model is driven by a specification of a prior distribution in the mean and variance of the process. Simple approximations are developed for the posterior estimates of the model parameters to enable its use by shop floor personnel. It is based upon specifications in the sensitivity of the control chart procedure to special cause phenomena when the chart is operated in its stationary phase. Ani.i.d.process is simulated to determine the required control chart standard deviation multiplier to achieve an in-control average run length (ARL) of 500. The results of simulation runs of 5000 replicates are evaluated for a range of settings of the EWMA weighting factor.

ISSN:0020-7543    

DOI:10.1080/00207549508904847

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor