Showing papers in "Journal of the Operational Research Society in 1994"
TL;DR: In this article, multiple regression is used to test and interpret multiple regression interactions in the context of multiple-agent networks. But it is not suitable for single-agent systems, as discussed in this paper.
Abstract: (1994). Multiple Regression: Testing and Interpreting Interactions. Journal of the Operational Research Society: Vol. 45, No. 1, pp. 119-120.
13,068 citations
TL;DR: This book proposes a unified mathematical treatment of a class of 'linear' discrete event systems, which contains important subclasses of Petri nets and queuing networks with synchronization constraints, which is shown to parallel the classical linear system theory in several ways.
Abstract: This book proposes a unified mathematical treatment of a class of 'linear' discrete event systems, which contains important subclasses of Petri nets and queuing networks with synchronization constraints. The linearity has to be understood with respect to nonstandard algebraic structures, e.g. the 'max-plus algebra'. A calculus is developed based on such structures, which is followed by tools for computing the time behaviour to such systems. This algebraic vision lays the foundation of a bona fide 'discrete event system theory', which is shown to parallel the classical linear system theory in several ways.
1,424 citations
TL;DR: A neglected aspect of Data Envelopment Analysis: cross-efficiency is examined, and an intuitive understanding of cross- efficiency is ground in the concept of peer-appraisal, as opposed to self-appRAisal implied by simple efficiency.
Abstract: In this paper we examine a neglected aspect of Data Envelopment Analysis: cross-efficiency. We develop the concept of cross-efficiency in a number of new directions. We ground an intuitive understanding of cross-efficiency in the concept of peer-appraisal, as opposed to self-appraisal implied by simple efficiency, and discuss the relative merits of each. We also present mathematical formulations of, and intuitive meanings for three possible implementations of aggressive and benevolent cross-efficiency. We have implemented two of these formulations in computer programs; their performance is compared empirically on a real data set. Finally, we suggest practical uses for cross-efficiency, illustrated with reference to the same data set.
1,127 citations
TL;DR: Inventory models where lead time is one of the decision variables are discussed, whether deterministic or probabilistic, and how this affects decision making in certain cases.
Abstract: Most of the literature dealing with inventory problems assumes lead time as prescribed, whether deterministic or probabilistic. In certain cases, lead time can be reduced but at an added cost. In t...
373 citations
324 citations
TL;DR: In this paper, the authors present strategies for reducing costs and improving services in Logistics and Supply Chain Management (LMSM) using a combination of cost-effective and cost-efficient strategies.
Abstract: (1994). Logistics and Supply Chain Management: Strategies for Reducing Costs and Improving Services. Journal of the Operational Research Society: Vol. 45, No. 11, pp. 1341-1341.
281 citations
TL;DR: In this paper, NIMSAD, a Systemic Framework for Understanding and Evaluating Methodologies (NIMSDA), is presented, which is based on the concept of understanding and evaluating methodologies.
Abstract: (1996). Understanding and Evaluating Methodologies: NIMSAD, A Systemic Framework. Journal of the Operational Research Society: Vol. 47, No. 4, pp. 594-595.
258 citations
TL;DR: In this paper, the authors extend the EPL model to cases where the production rate is a decision variable, and they show that the quality of the production process deteriorates with an increased production rate.
Abstract: The classical economic production lot size (EPL) model assumes a constant production rate that is predetermined and inflexible, and perfect quality. Recent models have removed the assumption of perfect quality while maintaining the inflexible production rate assumption. Production rates in many cases, such as orders filled by a machine, can be changed. Moreover, unit production cost and process quality depend on the production rate. In this paper, we extend the EPL model to cases where the production rate is a decision variable. Unit production cost becomes a function of the production rate. Also, the quality of the production process deteriorates with increased production rate. We solve the proposed model for special cost and quality functions and illustrate the results with a numerical example. The results show that, for cases where increases in the production rate lead to a significant deterioration in quality, the optimal production rate may be smaller than the rate that minimizes unit production cost. For cases where quality is largely independent of the production rate, the optimal production rate may be larger than the rate that minimizes unit production cost.
220 citations
TL;DR: The scheduling problem in the no-wait or constrained flowshop, with the makespan objective, is considered and a simple heuristic algorithm is proposed on the basis of heuristic preference relations and job insertion that is fairly accurate and much superior to those given by the two existing heuristics.
Abstract: The scheduling problem in the no-wait or constrained flowshop, with the makespan objective, is considered in this article. A simple heuristic algorithm is proposed on the basis of heuristic preference relations and job insertion. When evaluated over a large number of problems of various sizes, the solutions given by the proposed heuristic are found to be fairly accurate and much superior to those given by the two existing heuristics.
213 citations
196 citations
TL;DR: In this paper, a robust optimization model for planning power system capacity expansion in the face of uncertain power demand is developed. But the model is not suitable for the case of large-scale power systems.
Abstract: We develop a robust optimization model for planning power system capacity expansion in the face of uncertain power demand. The model generates capacity expansion plans that are both solution and model robust. That is, the optimal solution from the model is ‘almost’ optimal for any realization of the demand scenarios (i.e. solution robustness). Furthermore, the optimal solution has reduced excess capacity for any realization of the scenarios (i.e. model robustness). Experience with a characteristic test problem illustrates not only the unavoidable trade-offs between solution and model robustness, but also the effectiveness of the model in controlling the sensitivity of its solution to the uncertain input data. The experiments also illustrate the differences of robust optimization from the classical stochastic programming formulation.
TL;DR: A comparison between two methods to prevent overfitting is presented: finding the most appropriate network size, and the use of an independent validation set to determine when to stop training the network.
Abstract: This paper presents an empirical comparison of three classification methods: neural networks, decision tree induction and linear discriminant analysis. The comparison is based on seven datasets with different characteristics, four being real, and three artificially created. Analysis of variance was used to detect any significant differences between the performance of the methods. There is also some discussion of the problems involved with using neural networks and, in particular, on overfitting of the training data. A comparison between two methods to prevent overfitting is presented: finding the most appropriate network size, and the use of an independent validation set to determine when to stop training the network.
TL;DR: In this article, the authors relax the assumption that the cumulative distribution function of the lead time demand is completely known and merely assume that the first two moments of F are known and finte.
Abstract: Stochastic inventory models, such as continuous review models and periodic review models, require information on the lead time demand. However, information about the form of the probability distribution of the lead time demand is often limited in practice. We relax the assumption that the cumulative distribution function, say F, of the lead time demand is completely known and merely assume that the first two moments of F are known and finte. The minmax distribution free approach for the inventory model consists of finding the most unfavourable distribution for each decision variable and then minimizing over the decision variable. We solve both the continuous review model and the periodic review model with a mixture of backorders and lost sales using the minmax distribution free approach.
TL;DR: In this article, the authors consider the factors that should be included in any complete evaluation of market forecasting and describe how a company produces its market forecasts, and the perceptions of its managers as to inadequacies in the procedures, concluding with a discussion of the causes behind the organization's mismanagement of their forecasting activity.
Abstract: Quantitative forecasting techniques are not much used in organizations. Instead, organizations rely on the judgement of managers working close to the product market. Increasingly however, developments at the interface between marketing and operations require more accurate forecasting. Quantitative marketing models have that potential. Drawing on theories from the ‘diffusion of innovation’ literature and results on ‘the barriers to effective implementation’, this paper first considers those factors that should be included in any complete evaluation of market forecasting. Using this framework and based on detailed survey work in a multi-divisional organization, the paper then describes how this company produces its market forecasts, and the perceptions of its managers as to inadequacies in the procedures. Reasons are proposed as to why quantitative forecasting techniques are not effectively used. The paper concludes with a discussion of the causes behind the organization's mismanagement of their forecasting activity and how these activities might best be improved.
TL;DR: An ordering policy for raw materials to meet the requirements of a production facility which, in turn, must deliver finished products demanded by outside buyers at fixed interval points in time is developed.
Abstract: A manufacturing system which procures raw materials from suppliers and processes them to convert to finished products is considered here. This paper develops an ordering policy for raw materials to meet the requirements of a production facility which, in turn, must deliver finished products demanded by outside buyers at fixed interval points in time. First, a general cost model is developed considering both supplier (of raw material) and buyer (of finished products) sides. This model is used to determine an optimal ordering policy for procurement of raw materials, and the manufacturing batch size to minimize the total cost for meeting equal shipments of the finished products, at fixed intervals, to the buyers. The total cost is found to be a piece-wise convex cost function. An interval that contains the optimal solution is first determined followed by an optimization technique to identify the exact solution from this interval.
TL;DR: Buying Greenhouse Insurance outlines a way to think about greenhouse-effect decisions under uncertainty and describes an insightful model for determining the economic costs of limiting carbon dioxide emissions produced by burning fossil fuels and provides a solid analytical base for rethinking public policy on the farreaching issue of global warming.
Abstract: This book contains an economic analysis of various options in managing a potential global warming problem, arguing that sensible public policy requires balancing benefits and costs. The authors focus on two major questions: what will reductions in emissions buy in terms of reduced environmental damages and what will the price tag be?
TL;DR: In this paper, data envelopment analysis (DEA) is used to guide secondary schools to improved performance through role-model identification and target setting in a way which recognises the multi-outcome nature of the education process and reflects the relative desirability of improving individual outcomes.
Abstract: The educational process is characterised by multiple outcomes such as the achievement of academic results of various standards and non-academic achievements. This paper shows how data envelopment analysis (DEA) can be used to guide secondary schools to improved performance through role-model identification and target setting in a way which recognises the multi-outcome nature of the education process and reflects the relative desirability of improving individual outcomes. The approach presented in the paper draws from a DEA-based assessment of the schools of a local education authority carried out by the authors. Data from that assessment are used to illustrate the approach presented in the paper. (Key words: Data envelopment analysis, education, target setting.)
TL;DR: In this article, the authors present linear network optimization: Algorithms and Codes, which is a generalization of Linear Network Optimization (LNO) and Linear Network Programming (LNP).
Abstract: (1994). Linear Network Optimization: Algorithms and Codes. Journal of the Operational Research Society: Vol. 45, No. 4, pp. 483-483.
TL;DR: This paper proposes two heuristic methods: a fast straightforward insertion procedure and a method based on tabu search techniques that can reduce the total distance travelled when used in a real-life vehicle routeing problem in a major Swiss company producing pet food and flour.
Abstract: In this paper, we consider a real-life vehicle routeing problem that occurs in a major Swiss company producing pet food and flour. In contrast with usual hypothetical problems, a large variety of restrictions has to be considered. The main constraints are relative to the accessibility and the time windows at customers, the carrying capacities of vehicles, the total duration of routes and the drivers' breaks. To find good solutions to this problem, we propose two heuristic methods: a fast straightforward insertion procedure and a method based on tabu search techniques. Next, the produced solutions are compared with the routes actually covered by the company. Our outcomes indicate that the total distance travelled can be reduced significantly when such methods are used.
TL;DR: This paper describes a two-step algorithm for solving the layout problem while assuming the departments can have varying areas using a heuristic cutting plane routine, which is the only algorithm to solve a general dynamic layout problem with varying department areas.
Abstract: This paper describes a two-step algorithm for solving the layout problem while assuming the departments can have varying areas. The first step solves a quadratic assignment problem formulation of the problem using a heuristic cutting plane routine. The second step solves a mixed-integer linear programming prob- lem to find the desired block diagram layout. The algorithm incorporates two concepts to make the solu- tions more practical. First, rearrangement costs are simultaneously considered along with flow costs in solving a dynamic layout problem involving multiple time periods. It is the only algorithm to solve a general dynamic layout problem with varying department areas. Second, regular department shapes are maintained by requiring all departments to be rectangular. Its formulation for doing this is more efficient than previous algorithms.
TL;DR: This paper demonstrates how a multicriteria decision model (MCDM) using an analytic hierarchy process (AHP) can overcome the difficulties arising from the complexity, subjectivity and lack of group consensus in the evaluation of advertising agency selection criteria.
Abstract: This paper demonstrates how a multicriteria decision model (MCDM) using an analytic hierarchy process (AHP) can overcome the difficulties arising from the complexity, subjectivity and lack of group consensus in the evaluation of advertising agency selection criteria. The model was applied to a publishing house reviewing their selection procedures, providing a list of prioritized values of agency criteria, which ultimately influence agency selection. It was discovered how the level of potential decision making influence, or power, affects the overall group priorities and rankings of criteria by comparing three computer simulations for allocating power amongst the group using Expert Choice Software. The findings suggested that dominant power may not always be critical in affecting group rankings. Any critical level of dominance was subsequently identified using sensitivity analysis. By encouraging reflection and revision, the technique has much potential for improving contributions amongst the group, and restraining critical levels of dominance.
TL;DR: In this paper, a simple Gompertz curve-fitting procedure is proposed for forecasting the stock of cars in the Netherlands, where the stability of the saturation level over a sample period can be checked and no knowledge of its value is necessary for forecasting.
Abstract: In this paper, a simple Gompertz curve-fitting procedure is proposed. Its advantages include the facts that the stability of the saturation level over the sample period can be checked, and that no knowledge of its value is necessary for forecasting. An application to forecasting the stock of cars in the Netherlands illustrates its merits.
TL;DR: The problem of assigning a common due-date and sequencing a set of simultaneously available jobs on several identical parallel-machines is considered and it is shown that the problem is NP-hard with either a total or a maximal penalty function.
Abstract: We consider the problem of assigning a common due-date and sequencing a set of simultaneously available jobs on several identical parallel-machines The objective is to minimize some penalty function of earliness, tardiness and due-date values We show that the problem is NP-hard with either a total or a maximal penalty function For the problem with a total penalty function, we show that the special case in which all jobs have an equal processing time is polynomially-solvable
TL;DR: This paper presents arguments following a postmodern route which views the world as text, where all phenomena and events can be regarded as text and, as such, subject to narrative analysis.
Abstract: The texts of OR are littered, explicitly and implicitly, with myths about the ‘expert’ that are taken for self-evident truths. We would like to challenge these. This paper presents arguments following a postmodern route which views the world as text, where all phenomena and events can be regarded as text and, as such, subject to narrative analysis. Narrative analysis explodes and disperses text to reveal forms and codes according to which meanings are possible. The paper will introduce a case study drawing on our experiences in community OR, which we aim to use to demonstrate this approach.
TL;DR: In this article, the authors present a new approach for global optimization: deterministic approaches (2nd edition) which is based on the deterministic approach of the Operational Research Society (ORS).
Abstract: (1994). Global Optimization: Deterministic Approaches (2nd Edition) Journal of the Operational Research Society: Vol. 45, No. 5, pp. 595-597.
TL;DR: In this article, the authors discuss SSM and its relevance to information systems using SSM in the design of information systems reorienting information systems strategy the role of methodologies in systems strategy development experience of using Multiview empowering the client the appreciative enquiry method modelling subjective requirements objectively new challenges and directions for data analysis and modelling.
Abstract: SSM and its relevance to the development of information systems using SSM in the design of information systems reorientating information systems strategy the role of methodologies in systems strategy development experience of using Multiview empowering the client the appreciative enquiry method modelling subjective requirements objectively new challenges and directions for data analysis and modelling.
TL;DR: The 1992/93 Australian domestic state cricket season was scheduled using the method of simulated annealing, which carried out in conjunction with the Australian Cricket Board and the results were used with some manual modification to produce the final cricket programme.
Abstract: The 1992/93 Australian domestic state cricket season was scheduled using the method of simulated annealing. This included both first-class matches (four days each) and one-day games. The matches had to be scheduled around international fixtures and had to respect a variety of other constraints of varying importance. The work was carried out in conjunction with the Australian Cricket Board and the results were used with some manual modification to produce the final 1992/93 cricket programme.
TL;DR: English county cricket tournaments are run on a league basis as discussed by the authors, where every county plays against every other county exactly once over the season, which lasts from late April to mid-September.
Abstract: Eighteen teams currently compete in the major English county cricket tournaments (although one of the teams is Welsh, the system as a whole is generally known as ‘English’ cricket, and is referred to as such throughout this paper). There are four such competitions: the County Championship, the Sunday League and two knock-out cups. The first two of these are run on a league basis; under the current format, every county plays against every other county exactly once over the season, which lasts from late April to mid-September.