摘要:

We present an approach to modeling practical dynamic production planning problems with product sequencing considerations that yields a significant reduction in the number of required binary variables over traditional approaches and improves the structure of special ordered sets which can be exploited in state-of-the-art mixed integer programming codes. In addition, the variable definition enables the modeler to develop a wide variety of objective functions, thus facilitating model development and interpretation.

ISSN:0740-817X    

DOI:10.1080/07408178508975265

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A generalization of cyclical work-force scheduling is presented. We compute the minimal number of workers needed for a seven-days-a-week operation to satisfy cyclic demand forDworkers every weekday andEworkers every weekend day, while giving each worker two days off per week, includingAout ofBweekends off, for anyAandB (A < B).Using this workforce, the generalized cyclical scheduling procedure produces a feasible “master rotation” schedule, which additionally maintains all work stretches between two and four days (unless a worker gets two successive weekends off, in which case he works Monday through Friday), and which gives adjacent weekdays off, as often as possible, to any worker who must work on successive weekends. It is shown that the latter condition can be satisfied for all workers in almost all instances.

ISSN:0740-817X    

DOI:10.1080/07408178508975266

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Comparative Estimating is a work measurement technique which can be used for setting time standards on low repetitive tasks, such as may be met with in the maintenance area. It has been in wide use since 1955 and has probably been more commonly known as Universal Maintenance Standards (UMS). Since its introduction, the concepts of UMS have hardly changed and several reasons could be put forward for this; however, they would be speculative and would serve no real purpose. What is more important is that after almost 30 years it is perhaps time to re-examine the concept. In this paper the concept of Comparative Estimating is re-examined and an alternative approach, which has several advantages, is suggested. Its basic concept is first described with reference to UMS, identifying the problems of time and cost which are associated with this approach. The alternative approach is then outlined. The advantages which can be obtained from this approach are then identified by comparing some of the performance characteristics of the two approaches.

ISSN:0740-817X    

DOI:10.1080/07408178508975267

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

In this paper we consider the joint replenishment problem in the light of recent work by the second and third authors concerning the selection of realistic and consistent reorder intervals in production/ distribution systems. After stating a general dynamic programming formulation of the joint replenishment problem, we present its usual statement which assumes constant reorder intervals. We then restrict the problem further by assuming the constant reorder intervals are powers-of-two multiples of some base planning interval. We present an algorithm based on concepts we developed that solves the joint replenishment problem with the powers-of-two restriction. Like other algorithms proposed for this problem, it is a simple sorting algorithm. Finally, we establish that the algorithm yields a solution whose average annual cost is within 6% of the general problem's long-run minimum average annual cost.

ISSN:0740-817X    

DOI:10.1080/07408178508975268

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

This paper reviews the previous research on the problem of determining optimal lot sizes when production costs decrease on a log-linear function. Problems due to simplifying assumptions of the previous work are discussed and modifications of previous models are presented to address more realistic conditions. Using a dynamic programming approach, the new results for two cases of learning, total transmission of learning (from lot to lot) and partial transmission, indicate that optimal lot sizes are increasing in the long-run and long transient states exist, contrary to conclusions of prior papers. The effect of forgetting indicates that operations managers should consider longer production runs for many processes.

ISSN:0740-817X    

DOI:10.1080/07408178508975269

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

This article describes a methodology by which Decision Support Systems can be better understood by the Industrial Engineer. For years the IE has been at the forefront of technological change in the industrial arena, leading management and decision makers of all kinds in the use of appropriate tools as aids in the decision making process. One such tool has been Information Systems. IE's, as with the use of other tools, have been at the forefront in their planning and use, albeit not in their development. While the information systems industry has evolved from a transaction processing orientation to full-scale computer-based information systems orientation there seems to be a reticence on the IE's part in bringing the full power of the computer into the realm of the decision maker. Although attempts have been made over the years to define a decision support system for the decision maker, the implementation of that technology has been slow and extremely limited in scope. The authors of this paper propose that the slowness to develop adequate decision systems is more of a symptom of poor understanding of the decision process rather than a lack of technological skill. This paper reviews, in a general sense, the decision process, the evolution of information systems as currently understood by Industrial Engineers, and the current efforts in the area of Decision Support Systems. An attempt is then made to chart a course for the future: a course for IE's to follow and a course in which Decision Support Systems can be expected to follow.

ISSN:0740-817X    

DOI:10.1080/07408178508975270

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

paper describes a new procedure for obtaining satisfactory solutions to multiple-response, multiple-input simulation models. A modified version of response surface methodology is incorporated to obtain input values which meet user specified goals for the responses. The approach is illustrated with three examples which demonstrate the method. The desirability of incorporating this approach into an interactive computer mode is also discussed.

ISSN:0740-817X    

DOI:10.1080/07408178508975271

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Application of heuristic solution procedures to the resource-constrained, multi-project scheduling problem is analyzed under equal and unequal penalties. The performance of ten scheduling rules is categorized with respect to four project summary measures, namely, resource-constrainedness, location of the peak requirements, and problem size. It is shown that the choice of a scheduling rule can be based upon the resource-constrainedness, problem size, and penalty. These results are based on scheduling, in detail, over 3000 multi-project scheduling problems, each containing three projects and from 24 to 66 activities.

ISSN:0740-817X    

DOI:10.1080/07408178508975272

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

It has been suggested that the skewness of the probability distribution of the net present value of an investment should be a consideration in judging its desirability. This paper presents an index, referred to as the Expected Value – Variance – Skewness criterion, that incorporates skewness of net present value with its expected value and variance as a measure of investment worth under risk. The effectiveness of this criterion was compared to the expected value and the expected value-variance decision criteria by applying each criterion in a long sequence of investment projects.

ISSN:0740-817X    

DOI:10.1080/07408178508975273

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

This study presents various models for energy planning for the year 2000 in Puerto Rico. Puerto Rico depends on imported oil for 99% of its energy needs. The island has many promising energy sources such as biomass (sugar cane bagasse), photovoltaics (solar energy), ocean thermal energy conversion (OTEC), and wind power systems (WPS). These energy sources present some trade-offs in costs, pollution level, and fuel importation, which are studied. Uncertainty in future demand is taken into account. Integer variables representing the possible electricity generation plants are defined. The best compromise solution using the global criterion method for multiple objectives is presented. The proven alternatives such as coal-steam plants, nuclear plants, and biomass steam plants could have political constraints. New technologies such as photovoltaics, OTEC, and WPS possess many uncertainties. Should the cost of these alternatives be less than the electricity generated using oil, a combination of these energy sources would represent the best alternatives to solve Puerto Rico's electricity needs.

ISSN:0740-817X    

DOI:10.1080/07408178508975274

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor