A cost-effective approach to stochastic line balancing with off-line repairs

The layout of production facilities is an important determinant of the productivity potential of a manufacturing enterprise. It is particularly important in the design of assembly lines where the objective is to assign tasks to work stations in such a way as to minimize total variable production costs.Early approaches to the line balancing problem assumed known constant task times and sought a line layout which would produce the desired output with the fewest number of work stations, which is equivalent to minimizing idle time. Studies have shown that task times are random variables, therefore the cost of task incompletion must be considered a part of total production cost. Incompletion cost will be the cost of repairing or completing tasks which cannot be completed within the cycle time after the item has reached the end of the assembly line.This paper describes a methodology for designing approximately minimum cost paced assembly lines under conditions of random task times and off-line repair of incompleted tasks. Task times are assumed to be normally distributed random variables with known means and variances. The methodology consists of heuristically identifying a large number of feasible balances for each of which total costs are computed. The line design with the lowest total is retained as the “best.”In order to evaluate candidate line layouts, a total cost model is developed. Total cost is the sum of normal operating cost—which is simply a function of the number of work stations—and the cost of repairing products containing incompleted tasks. Because this latter cost is a random variable for a given balance, the expected value is used to evaluate a candidate layout. The cost associated with one or more workers exceeding the cycle time is the product of the probability of this happening and the expected cost of off-line repair.The heuristic method for generating feasible balances builds work stations from continually updated lists of precedence satisfying tasks. Qualifying tasks are added to the station as long as the probability of the station exceeding the cycle time remains below a pre-specified threshold. The methodology requires systematically varying this threshold to permit a lowest total cost solution to emerge. The process of generating a large number of balances for a particular threshold is efficient. Evaluating the total costs of the resulting balances takes the majority of the computational time.An experiment was conducted in order to compare the above cost-effective methodology with a purely deterministic approach and a commonly used industrial approximation method for dealing with task time variability. The experiment applied the three methods to four problems from the literature under a variety of repair cost and time variance conditions. In 21 of the 24 cases studied, the stochastic method produced a lower cost balance than the two alternatives. In the remaining 3 cases, the deterministic method also found the lowest cost balance. The stochastic method saved an average of 22.5 percent in total operating cost over the deterministic method and 8.4 percent over the industrial method.The experiment clearly showed the need to explicitly consider task time variability in arriving at a line balance. The stochastic approach of this paper offers large potential savings with no risk of obtaining a less desirable balance and so should be considered for implementation whenever there is a variation in task times. Even for large-scale problems, the computational cost is infinitesimal in the context of assembly line balancing, where very small improvements in productivity can mean substantial increments to profitability.     

炼钢厂降低生产线成本方法研究

2015年钢铁行业产能过剩,低价格、低效益局面继续在行业蔓延。各大钢铁企业利润持续降低,都面临降低生产成本难题。文章通过对炼钢厂生产线特点以及生产成本分析,提出了导入先进管理方式和创新发展模式的方法,以降低企业生产线成本。     

A method for quantitative evaluation of burglary resistance

Quantitative models which could be used for comparison of security systems do not seem to be available in the literature. This paper presents a model which could be used to compare the resistance to burglary of differing building designs. Emphasis is on the burglary of apartments. The model is a stochastic process, and computes the probability of successful burglary, and also the probability of burglars being thwarted without being able to attempt entry into an apartment.     

作业成本法与传统的制造费用分配法的比较

<正> 现代企业制度的特点是产权明晰、责权分明以及科学管理、政企分开。成本管理是企业管理的一个重要方面。正确的成本计算方法,能够提供正确的会计信息资料,有利于企业各项改革措施协调一致、齐头并进地推动各项专业管理朝着科学方向发展。     

烟草专卖网格化管理中的零售终端动态评价方法研究

文章以当前烟草行业的网格化管理实践为基础,研究构建烟草零售终端的评价指标体系,并引入动态管理的理念,研究烟草零售终端分类中的等级转化机制,以望江县烟草网格化管理实践为例进行实证研究,由此体现烟草零售终端的分类管理和动态评价在烟草专卖市场监管中的积极作用。     

论成本性态分析中的混合成本分解方法

成本性态又称成本习性 ,是指成本总发生额与业务量之间的依存关系。进行成本性态分析就是要考察成本发生额与业务量之间规律性的联系。按照成本对业务量的依存关系 ,我们通常将成本区分为固定成本、变动成本和混合成本三类。按照一定的方法把混合成本分解为变动成本和固定成本 ,叫做混合成本的分解。其分解方法有以下几种 :一、合同确认法合同确认法是通过检查与其他单位签订的合同中有关支付费用的具体规定 ,来确定成本中的固定成本和变动成本的。二、技术测定法技术测定法又称技术估算法 ,是通过技术测定与估算的办法来划分成本中的固定成…     

An impulse-control method for investment decisions in dynamic technology

This paper presents a new framework to augment standard methods in evaluating profitability of investments, especially those involved in dynamic technology. In this case there is a possibility that although a certain investment is profitable using standard methods, it should not be undertaken because it precludes a more profitable investment later on, when more advanced equipment will be available. The investment decision faced by a firm is presented here as an impulse-control problem, where the process of technological progress is modelled explicitly. The outcome of the optimization yields, in addition to investment expenditures, the expected time period between consecutive investments. A simple example demonstrates the use of the technique in actual investment decisions.     

A component model for dynamic correlations

We propose a model of dynamic correlations with a short- and long-run component specification, by extending the idea of component models for volatility. We call this class of models DCC-MIDAS. The key ingredients are the Engle (2002) DCC model, the Engle and Lee (1999) component GARCH model replacing the original DCC dynamics with a component specification and the Engle et al. (2006) GARCH-MIDAS specification that allows us to extract a long-run correlation component via mixed data sampling. We provide a comprehensive econometric analysis of the new class of models, and provide extensive empirical evidence that supports the model’s specification.     

A fine balancing act: Freedom and accountability

The recent Funding Options Review identified a minimum additional funding requirement of 900 million per annum for higher education by 2004/05 and also considered more specific needs, such as correcting for past under-investment in infrastructure. At the same time, it contributed to the debate about the'key choice'of funding by government or by the'beneficiaries of higher education.'Government will need to match its aspirations for higher education with adequate funding and the universities will have to be'even more sensitive and responsive to the needs of students.'     

A fine balancing act: freedom and accountability

The recent Funding Options Review identified a minimum additional funding requirement of 900 million per annum for higher education by 2004/05 and also considered more specific needs, such as correcting for past under-investment in infrastructure. At the same time, it contributed to the debate about the‘key choice’of funding by government or by the‘beneficiaries of higher education.’Government will need to match its aspirations for higher education with adequate funding and the universities will have to be‘even more sensitive and responsive to the needs of students.’     

试论作业成本法在物流成本管理中的应用

从历史发展过程来看,人类社会经济发展曾经先后出现过两个大量提供利润的领域,第一个是资源领域,第二个是人力领域。前习惯称为“第一利润源”,后习惯称为“第二利润源”,在这两个利润源潜力越来越小,利润开拓越来越困难的情况下,物流领域的潜力越来越被人们所重视,并被称为“第三利润源”。物流管理将是挖掘“第三利润”的直接手段,中通过对物流管理中的中心问题－物流成本管理的探讨来阐述企业应用作业成本法对加强物流成本核算和物流成本管理的必要性。     

A note on the balancing factors of gravity models

Application of the production constrained gravity-type spatial interaction model generally incorporates a “balancing of attractions” procedure to yield the fully constrained condition. Two techniques for balancing a singly constrained gravity model are compared in this note. These are the Federal Highways Administration adjusted attraction factor method and the Furness column and row balancing procedure. This comparison shows firstly that the two techniques are identical, and secondly that the balancing procedure results in an arbitrary distortion of the calibrated distribution function. Furthermore, some empirical results show that the balancing procedure does not necessarily improve the model's predictions on a cell by cell basis. These results indicate that balancing may be an unnecessary as well as undesirable step in the application of the singly constrained gravity model.     

A stochastic frontier cost function for residential child care provision

Within a public authority (the firm), there are often several production units. Costs and policy formulation are concerned with the units themselves, though inefficiency might arise at both the firm and unit levels. A stochastic frontier cost function is developed and estimated to describe one such situation where the firms are English local authorities and the production units are homes providing residential care for children. Measures of inefficiency are found for individual authorities.     

A suggested methodology for calculating the cost of university graduates

Costs are the valuations placed on the use of resources; they include operating and opportunity costs. As such they vary according to one's orientation. In higher education, costs can be evaluated from the point of view of three entities: the university as an economic firm (institutional cost); the students as private individuals (private cost); and society at large (social cost). This paper considers the institutional costs of higher education.Based on a hypothetical college model, two methodologies are suggested for evaluating the institutional costs in the “production’ of university graduates. The net-value-added method assumes that the cost of dropouts is inherent in the cost of graduates. The cost-per-student-year method assumes that dropouts and graduates are joint products of the educational system each with their own separate costs.The application of the two cost models is demonstrated with empirical data based on the University of Mosul in Iraq. The implications of the suggested methodologies for institutions with diverse specializations, high dropout rates, or large proportions of transfer students are also discussed.     

A strategy for the cost containment of surgical implant purchases

Although the experience of the Hospital for Joint Diseases is unique in terms of size of market controlled, the cost-containment techniques described above are applicable to almost any hospital. A crucial factor in any such process is enlisting the active participation of the surgical staff at every stage. On the basis of the success, this cost-containment procedure is being applied to other components of the medical device purchases.     

A dynamic priority rule for scheduling against due-dates

We simulate the performance of a simple production system in which due-dates are set internally. We investigate priority rules aimed at minimizing tardiness, emphasizing a “modified duedate rule” which functions effectively in conjunction with internally-set deadlines and which adapts to both tight and loose conditions in the due-dates. This rule is simple and logical, and shows considerable promise for application in complex production systems.