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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2007.10.019 Byline: Kazuki Matsumoto (a), Hiroyoshi Miwa (b), Toshihide Ibaraki (b) Keywords: Scheduling; Corrugated paper; Complexity; Contiguous set; Integer programming Abstract: Corrugated paper is produced by gluing three types of papers of the same breadth. Given a set of orders, we first assign each order to one of the standard breadths, and then sequence those assigned to each standard breadth so that they are continuously manufactured from the three rolls of the specified standard breadth equipped in the machine called corrugator. Here we are asked to achieve multi-goals of minimizing total length of roll papers, total loss of papers caused by the differences between standard breadths and real breadths of the orders, and the number of machine stops needed during production. We use integer programming to assign orders to standard breadths, and then develop a special purpose algorithm to sequence the orders assigned to each standard breadth. This is a first attempt to handle scheduling problems of the corrugator machine. Author Affiliation: (a) Department of Applied Mathematics and Physics, Graduate School of Informatics, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan (b) Department of Informatics, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen Sanda, Hyogo 669-1337, Japan Article History: Received 24 March 2007; Accepted 5 October 2007

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2007.08.033 Byline: Philip C. Jones, Jeffrey W. Ohlmann Keywords: OR in agriculture; Forest economics; Normal forest; Regulated forest; Newsvendor model; Forestry supply chain management Abstract: We consider a vertically integrated papermaking operation composed of an integrated pulp and paper mill with its regional supply network. Considering land procurement and harvest rotation as strategic decision variables, we construct a model to establish a long-range timber supply plan that minimizes the total discounted cost of meeting annual virgin wood fiber demand over an infinite horizon. Under appropriate assumptions on costs and storage, the land procurement and harvest rotation decisions are separable with harvest rotation being determined via a forest economics-type equation and land procurement being determined by a newsvendor-type equation. Author Affiliation: Department of Management Sciences, 108 John Pappajohn Business Building, University of Iowa, Iowa City, IA 52242-1994, United States Article History: Received 18 January 2006; Accepted 24 August 2007

A container loading software package for solving the different problems involved in the containerization of pulp and paper products is presented. The software boasts of a packing algorithm for creating a two-dimensional pattern for placing reels on the floor of container, a heuristic algorithm for two-dimensional stowing of reels of a common diameter and a second packing algorithm for stowing pallets of various sizes. Its applicability has been validated in several decision situations which include the determination of feasible reel diameters and efficient stowage patterns.

Issues are presented concerning the primitive concepts and oversights in the 'jump search' heuristic presented by S. Tsubakitani and J.R. Evans in their research paper entitled 'An empirical study of a new metaheuristic for the traveling salesman problem'.

Usage of pairwise comparison method in sense of analytic hierarchy process to rank factors affecting industrial decision making process is discussed.

A revision was made of the Christofides, Alvarez-Valdez and Tamarit (CAT) procedure for solving the single project scheduling problem. A 9-activity counterexample problem was used to prove that the branching strategy that was originally implemented can generate nonoptimal solutions. The construction of additional precedence relations or delay arcs used in the original CAT procedure for delaying activities was proven to be highly restrictive.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2006.09.007 Byline: Eric Taillard Author Affiliation: HEIG-VD, University of Applied Sciences of Western Switzerland, 1, Route de Cheseaux, Case postale CH-1401 Yverdon-Les-Bains, Switzerland

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2005.08.011 Byline: J.B.G. Frenk Abstract: In this technical note, we give a short proof based on some standard results in convex analysis of some important characterization results listed in Theorems 3 and 4 of Benson [Benson, H.P., 2006. Fractional programming with convex quadratic forms and functions. European Journal of Operational Research]. Actually our result is slightly more general since we do not specify the nonempty convex set X. For clarity we use the same notation for the different equivalent optimization problems as done in Benson (2006). Author Affiliation: Econometric Institute, Erasmus University, P.O. Box 1738, 3000DR Rotterdam, The Netherlands Article History: Received 11 February 2005; Accepted 3 August 2005

Convex analysis of quadratic equations, using fractional programming, is discussed.

Research describing project scheduling problems is examined. In particular a critical analysis of classification schemes compatible with machine scheduling proposed by Brucker et al. is presented.

The trim loss problem of a paper-converting company is considered using mixed integer non-linear programming and mixed integer linear programming (MILP). The resulting algorithm incorporating MILP has been found to be globally optimal in generating cutting patterns as it takes into account widths and lengths of paper rolls as well as cutting patterns and constraints in conversion.

Supply chain problem of a large international pulp producer with five pulp mills located in Scandinavia is studied. The company currently uses manual planning for harvesting and transportation of pulp, production scheduling, and distribution of products to customers.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.07.009 Byline: Sangmun Shin (a), Pauline Kongsuwon (a), Byung Rae Cho (b) Keywords: Process parameters; Tolerance; Quality loss; Lambert W function; Optimization Abstract: Most of previous research on tolerance optimization seeks the optimal tolerance allocation with process parameters such as fixed process mean and variance. This research, however, differs from the previous studies in two ways. First, an integrated optimization scheme is proposed to determine both the optimal settings of those process parameters and the optimal tolerance simultaneously which is called a parametric tolerance optimization problem in this paper. Second, most tolerance optimization models require rigorous optimization processes using numerical methods, since closed-form solutions are rarely found. This paper shows how the Lambert W function, which is often used in physics, can be applied efficiently to this parametric tolerance optimization problem. By using the Lambert W function, one can express the optimal solutions to the parametric tolerance optimization problem in a closed-form without resorting to numerical methods. For verification purposes, numerical examples for three cases are conducted and sensitivity analyses are performed. Author Affiliation: (a) Department of Systems Management and Engineering, Inje University, Gimhae 621749, South Korea (b) Department of Industrial Engineering, Clemson University, Clemson, SC 29634, USA Article History: Received 5 December 2008; Accepted 7 July 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.06.020 Byline: David Hager (a)(b), Lasse B. Andersen (a) Keywords: Risk management; OR in financial institutions; Bayesian networks; Loss determinants; Advanced measurement approach Abstract: Modelling loss severity from rare operational risk events with potentially catastrophic consequences has proved a difficult task for practitioners in the finance industry. Efforts to develop loss severity models that comply with the BASEL II Capital Accord have resulted in two principal model directions where one is based on scenario generated data and the other on scaling of pooled external data. However, lack of relevant historical data and difficulties in constructing relevant scenarios frequently raise questions regarding the credibility of the resulting loss predictions. In this paper we suggest a knowledge based approach for establishing severity distributions based on loss determinants and their causal influence. Loss determinants are key elements affecting the actual size of potential losses, e.g. market volatility, exposure and equity capital. The loss severity distribution is conditional on the state of the identified loss determinants, thus linking loss severity to underlying causal drivers. We suggest Bayesian Networks as a powerful framework for quantitative analysis of the causal mechanisms determining loss severity. Leaning on available data and expert knowledge, the approach presented in this paper provides improved credibility of the loss predictions without being dependent on extensive data volumes. Author Affiliation: (a) University of Stavanger, Department of Industrial Economics, Risk Management and Planning, 4036 Stavanger, Norway (b) Bayes Risk Management AS, P.O. Box 6069, 4088 Stavanger, Norway Article History: Received 10 June 2009; Accepted 14 June 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.06.001 Byline: Wen Cao, Bo Jiang, Deming Zhou Keywords: Retailing; Demand uncertainty; Retail channel structure; Duopoly competition Abstract: Motivated by the business practice whereby some manufacturers open their own retail stores despite the existence of more efficient independent retailers, this paper examines the distribution channel choice of competing manufacturers under demand uncertainty and resale price maintenance. We characterize the conditions for the equilibrium channel structures. We find that (1) manufacturers tend to distribute products with more design attributes through their own retail stores, (2) manufacturers with highly substitutable products are more likely to use independent retailers, and (3) at least one manufacturer has more incentive to open its own retail stores when facing an increase of the market size asymmetry. Author Affiliation: Department of Decision Sciences and Managerial Economics, Faculty of Business Administration, The Chinese University of Hong Kong, Hong Kong Article History: Received 13 April 2009; Accepted 1 June 2010 Article Note: (footnote) [star] The authors are listed alphabetically and all authors contributed to the paper equally.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.07.016 Byline: M.K. Luhandjula (a), J.W. Joubert (b)(c) Keywords: Fuzziness; Randomness; Optimisation; Probabilistic set; Uncertain probability; Fuzzy random variable Abstract: This paper is on fuzzy stochastic optimisation, an area that is quickly coming to the forefront of mathematical programming under uncertainty. An even stronger motivating factor for the growing interest in this area can be found in the ubiquitous nature of decision problems involving hybrid imprecision. More precisely, we consider a range of situations in which random factors and fuzzy information co-occur in an optimisation setting. Related hybrid optimisation models are discussed and converted into deterministic terms through appropriate tools like probabilistic set, uncertain probability, and fuzzy random variable, making good use of uncertainty principles. We also discuss ways to deal with the resulting problems. Numerical examples carried out using class optimisation software demonstrate the efficiency of the proposed approaches. We shall end this article by pointing out some of the challenges that currently occupy researchers in this emerging field. Author Affiliation: (a) Department of Decision Sciences, University of South Africa, Pretoria, Unisa 0003, South Africa (b) Department of Industrial and Systems Engineering, University of Pretoria, Pretoria 0002, South Africa (c) Built Environment, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001, South Africa Article History: Received 2 September 2008; Accepted 14 July 2010 Article Note: (footnote) [star] An early version of this paper was presented at the NAFIPS 2008 Conference, New York, USA, May 2008.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.07.015 Byline: Pedro Godinho (a), Joana Dias (b) Keywords: Location; Game theory; Simultaneous decisions; Optimization algorithms; Nash equilibrium Abstract: In this paper we will describe and study a competitive discrete location problem in which two decision-makers (players) will have to decide where to locate their own facilities, and customers will be assigned to the closest open facilities. We will consider the situation in which the players must decide simultaneously, unsure about the decisions of one another, and we will present the problem in a franchising environment. Most problems described in the literature consider sequential rather than simultaneous decisions. In a competitive environment, most problems consider that there is a set of known and already located facilities, and new facilities will have to be located, competing with the existing ones. In the presence of more than one decision-maker, most problems found in the literature belong to the class of Stackelberg location problems, where one decision-maker, the leader, locates first and then the other decision-maker, the follower, locates second, knowing the decisions made by the first. These types of problems are sequential and differ significantly from the problem tackled in this paper, where we explicitly consider simultaneous, non-cooperative discrete location decisions. We describe the problem and its context, propose some mathematical formulations and present an algorithmic approach that was developed to find Nash equilibria. Some computational tests were performed that allowed us to better understand some of the features of the problem and the associated Nash equilibria. Among other results, we conclude that worsening the situation of a player tends to benefit the other player, and that the inefficiency of Nash equilibria tends to increase with the level of competition. Author Affiliation: (a) Faculdade de Economia and GEMF, Universidade de Coimbra, Av. Dias da Silva, 165, 3004-512 Coimbra, Portugal (b) Faculdade de Economia and Inesc-Coimbra, Universidade de Coimbra, Av. Dias da Silva, 165, 3004-512 Coimbra, Portugal Article History: Received 17 November 2009; Accepted 14 July 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.07.013 Byline: Ryusuke Hohzaki (a), Hiroki Maehara (b) Keywords: Dynamic programming; Game theory; Inspection game; Two-person zero-sum; Multi-period Abstract: This paper deals with an inspection game of Customs and a smuggler during some days. Customs has two options of patrolling or not. The smuggler can take two strategies of shipping its cargo of contraband or not. Two players have several opportunities to take an action during a limited number of days but they may discard some of the opportunities. When the smuggling coincides with the patrol, there occurs one of three events: the capture of the smuggler by Customs, a success of the smuggling and nothing new. If the smuggler is captured or no time remains to complete the game, the game ends. There have been many studies on the inspection game so far by the multi-stage game model, where both players at a stage know players' strategies taken at the previous stage. In this paper, we consider a two-person zero-sum single-shot game, where the game proceeds through multiple periods but both players do not know any strategies taken by their opponents on the process of the game. We apply dynamic programming to the game to exhaust all equilibrium points on a strategy space of player. We also clarify the characteristics of optimal strategies of players by some numerical examples. Author Affiliation: (a) Department of Computer Science, National Defense Academy, Yokosuka 239-8686, Japan (b) Japan Coast Guard, Japan Article History: Received 20 December 2009; Accepted 12 July 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.07.012 Byline: Derek Atkins (a), Liping Liang (b) Keywords: Marketing; Supply chain outsourcing; Channel competition Abstract: This note generalises models from two influential papers in the theory of supply chain outsourcing under competition: . The first paper studies the impact of competitive intensity on the outsourcing decision from the supplier's point of view for linear supply cost; the second paper examines the impact of supply economies of scale from the retailer's point of view when selling perfectly substitutable products. By considering competitive intensity and supply economies of scale simultaneously, we find that equilibrium channel structures are primarily determined by the competitive intensity, which is true even under supply diseconomies of scale; the key message in the second paper of scale economies driving retailer's outsourcing supply decision is highly dependent on the assumption of perfect substitutes. Our finding has no qualitative difference when either the suppliers or the retailers are modeled as the channel leader and make the outsourcing decisions. Author Affiliation: (a) Sauder School of Business, University of British Columbia, 2053 Main Mall, Vancouver, BC, Canada V6T 1Z2 (b) Department of Computing and Decision Sciences, Lingnan University, Tuen Mun, N.T., Hong Kong Article History: Received 1 December 2009; Accepted 9 July 2010 Article Note: (footnote) [star] The authors are grateful to the editor and two anonymous referees for their insightful comments that helped improve this note.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.05.016 Byline: E. Khorram, M. Zarepisheh, B.A. Ghaznavi-ghosoni Keywords: Multiple objective programming; Vector optimization; Preemptive priority; Lexicographic ordering; Sensitivity analysis Abstract: This paper deals with a class of multiple objective linear programs (MOLP) called lexicographic multiple objective linear programs (LMOLP). In this paper, by providing an efficient algorithm which employs the preceding computations as well, it is shown how we can solve the LMOLP problem if the priority of the objective functions is changed. In fact, the proposed algorithm is a kind of sensitivity analysis on the priority of the objective functions in the LMOLP problems. Author Affiliation: Faculty of Mathematics and Computer Science, Amirkabir University of Technology, 424, Hafez Avenue, 15914 Tehran, Iran Article History: Received 9 May 2008; Accepted 13 May 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.12.019 Byline: John Mingers (a), Leroy White (b) Keywords: Systems thinking; Systems approach; Complexity theory; System dynamics; Soft systems methodology; Cybernetics; Critical systems; Multimethodology Abstract: The systems approach, or systems thinking, has been intimately connected with the development of OR and management science initially through the work of founders such as Churchman and Ackoff and latterly through innovations such as soft systems. In this paper we have undertaken a review of the contribution that systems thinking has been making more recently, especially to the practice of OR. Systems thinking is a discipline in its own right, with many theoretical and methodological developments, but it is also applicable to almost any problem area because of its generality, and so such a review must always be selective. We have looked at the literature from both a theoretical and an applications orientation. In the first part we consider the main systems theories and methodologies in terms of their recent developments and also their applications. This covers: the systems approach, complexity theory, cybernetics, system dynamics, soft OR and PSMs, critical systems and multimethodology. In the second part we review the main domains of application: strategy, information systems, organisations, production and operations, ecology and agriculture, and medicine and health. Our overall conclusion is that while systems may not be well established institutionally, in terms of academic departments, it is incredibly healthy in terms of the quantity and variety of its applications. Author Affiliation: (a) Kent Business School, University of Kent, Canterbury CT7 2PE, UK (b) Department of Management, University of Bristol, UK Article History: Received 17 April 2009; Accepted 17 December 2009 Article Note: (footnote) [star] Because of the large number of references some of them are not printed with the paper but they are available online at the publisher's website. These references are cited in italics.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.07.005 Byline: Rommel G. Regis Keywords: Global optimization; Stochastic search; Random search; Convergence; Evolutionary algorithm; Evolutionary programming Abstract: This paper presents some simple technical conditions that guarantee the convergence of a general class of adaptive stochastic global optimization algorithms. By imposing some conditions on the probability distributions that generate the iterates, these stochastic algorithms can be shown to converge to the global optimum in a probabilistic sense. These results also apply to global optimization algorithms that combine local and global stochastic search strategies and also those algorithms that combine deterministic and stochastic search strategies. This makes the results applicable to a wide range of global optimization algorithms that are useful in practice. Moreover, this paper provides convergence conditions involving the conditional densities of the random vector iterates that are easy to verify in practice. It also provides some convergence conditions in the special case when the iterates are generated by elliptical distributions such as the multivariate Normal and Cauchy distributions. These results are then used to prove the convergence of some practical stochastic global optimization algorithms, including an evolutionary programming algorithm. In addition, this paper introduces the notion of a stochastic algorithm being probabilistically dense in the domain of the function and shows that, under simple assumptions, this is equivalent to seeing any point in the domain with probability 1. This, in turn, is equivalent to almost sure convergence to the global minimum. Finally, some simple results on convergence rates are also proved. Author Affiliation: Mathematics Department, Saint Joseph's University, Philadelphia, PA 19131, USA Article History: Received 29 September 2008; Accepted 3 July 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.05.043 Byline: Chenghu Ma (a), Wing-Keung Wong (b) Keywords: Decision analysis; Risk analysis; Risk attributes; Utility; Stochastic dominance Abstract: Is it possible to obtain an objective and quantifiable measure of risk backed up by choices made by some specific groups of rational investors? To answer this question, in this paper we establish some behavior foundations for various types of VaR models, including VaR and conditional-VaR, as measures of downside risk. In this paper, we will establish some logical connections among VaRs, conditional-VaR, stochastic dominance, and utility maximization. Though supported to some extents with unanimous choices by some specific groups of expected or non-expected-utility investors, VaRs as profiles of risk measures at various levels of risk tolerance are not quantifiable - they can only provide partial and incomplete risk assessments for risky prospects. We also include in our discussion the relevant VaRs and several alternative risk measures for investors; these alternatives use somewhat weaker assumptions about risk-averse behavior by incorporating a mean-preserving-spread. For this latter group of investors, we provide arguments for and against the standard deviation versus VaR and conditional-VaRs as objective and quantifiable measures of risk in the context of portfolio choice. Author Affiliation: (a) School of Management, Fudan University, China (b) Department of Economics and Institute for Computational Mathematics, Hong Kong Baptist University, Hong Kong Article History: Received 3 June 2009; Accepted 26 May 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.05.027 Byline: Dengfeng Zhang (a), Renato de Matta (b), Timothy J. Lowe (b) Keywords: Retailing; Production; Pricing; Channel coordination Abstract: With the emergence of virtual market places, consignment selling has been thriving at an unprecedented pace. It has been shown in the literature that inefficiency exists in a decentralized consignment channel with a single revenue share agreement. In our study, we analyze contracts observed in practice that contain bonus or side payment terms, and examine whether they can promote better coordination between the supplier and the retailer. We found that no multi-tier Bonus system can fully coordinate the consignment channel. However, fine adjustments of bonus parameters can bring the channel close to full coordination. Additionally, we found revenue sharing with side payment contracts not only fully coordinate the channel, but they can also be customized to meet the needs of small, medium and large suppliers for extra retailer services such as warehousing and transportation. Managerial insights on how to design the contracts from the supplier, retailer and channel perspectives are discussed in the paper. Author Affiliation: (a) Department of Computing and Decision Sciences, Lingnan University, Tuen Mun, Hong Kong (b) Department of Management Sciences, University of Iowa, Iowa City, IA 52242-1000, United States Article History: Received 18 December 2008; Accepted 19 May 2010 Article Note: (footnote) [star] The authors are grateful to two anonymous referees and the editor for their valuable comments and suggestions that helped improve the paper.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.04.011 Byline: M.N.M. Kahar (a)(b), G. Kendall (a) Keywords: Optimisation; Timetabling; Heuristic; Scheduling Abstract: This paper presents a real-world, capacitated examination timetabling problem from Universiti Malaysia Pahang (UMP), Malaysia. The problem has constraints which have not been modelled before, these being the distance between examination rooms and splitting exams across several rooms. These constraints provide additional challenges in defining a suitable model and in developing a constructive heuristic. One of the contributions of this paper is to formally define this real-world problem. A further contribution is the constructive heuristic that is able to produce good quality solutions for the problem, which are superior to the solutions that are produced using the university's current software. Moreover, our method adheres to all hard constraints which the current systems fails to do. Author Affiliation: (a) Automated Scheduling, Optimisation and Planning (ASAP) Group, School of Computer Science, University of Nottingham, Jubilee Campus, Nottingham, NG8 1BB, UK (b) Faculty of Computer Systems & Software Engineering, Universiti Malaysia Pahang, Locked Bag 12, Kuantan 25000, Pahang, Malaysia Article History: Received 15 July 2009; Accepted 8 April 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.05.049 Byline: Soushi Suzuki (a), Peter Nijkamp (b), Piet Rietveld (b), Eric Pels (b) Keywords: Distance friction minimization (DFM) method; Data envelopment analysis (DEA); Multiple Objective Quadratic Programming (MOQP); Efficiency improving projection; Airport efficiency Abstract: This paper aims to present a newly developed distance friction minimization (DFM) method in the context of data envelopment analysis (DEA) in order to generate an appropriate (non-radial) efficiency-improving projection model, for both input reduction and output increase. In this approach, a generalized distance function, based on a Euclidean distance metric in weighted spaces, is proposed to assist a decision making unit (DMU) to improve its performance by an appropriate movement towards the efficiency frontier surface. A suitable form of multidimensional projection function for efficiency improvement is given by a Multiple Objective Quadratic Programming (MOQP) model. The paper describes the various steps involved in a systematic manner. The above-mentioned DFM model is illustrated empirically by using a data set on 30 European airports, where the aim is to present a comparative analysis of the efficiency of operational management in these airports. In addition, the comparative analysis of these airports is able to assess both input slacks and output slacks (or a combination of input reduction and output rise). Author Affiliation: (a) Hokkai-Gakuen University, Department of Civil and Environmental Engineering, 1-1, South 26 West11, Chuo-ku, 064-0926 Sapporo, Japan (b) VU University Amsterdam, Department of Spatial Economics, De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands Article History: Received 14 November 2007; Accepted 31 May 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.01.014 Byline: Hsing Kenneth Cheng, Qian Candy Tang Keywords: Software free trial; Network effects; Information goods Abstract: A common business strategy to promote product adoption in software industry is to provide a free trial version with limited functionalities of the commercial product to increase the installed user base. The increase of user base will lead to higher value of the software because of positive network effects. However, offering a free trial version may cannibalize some demand of the commercial software. This paper examines the tradeoff between network effects and the cannibalization effect, and aims to uncover the conditions under which firms should introduce the free trial product. We find that when network intensity is strong, it is more profitable for a software monopoly to offer free trial than to segment the market with two versions of different qualities. In addition, this paper solves the joint decision problem of finding the optimal quality for the firm's free trial software and the optimal price of its commercial product. Author Affiliation: Department of Information Systems and Operations Management, Warrington College of Business Administration, University of Florida, Gainesville, FL 32611-7169, USA Article History: Received 9 August 2008; Accepted 7 January 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.12.008 Byline: John Mingers, Fang Xu Keywords: Citations; Impact factors; Journals; Research quality Abstract: The number of citations is becoming an increasingly popular index for measuring the impact of a scholar's research or the quality of an academic department. One obvious question is: what are the factors that influence the number of citations that a paper receives? This study investigates the number of citations received by papers published in six well-known management science journals. It considers factors that relate to the author(s), the article itself, and the journal. The results show that the strongest factor is the journal itself; but other factors are also significant including the length of the paper, the number of references, the status of the first author's institution, and the type of paper, especially if it is a review. Overall, this study provides some insights into the determinants of a paper's impact that may be helpful for particular stakeholders to make important decisions. Author Affiliation: Kent Business School, University of Kent, Canterbury CT7 2PE, UK Article History: Received 20 February 2009; Accepted 4 December 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.12.027 Byline: J.R. Figueira (a)(b), A. Liefooghe (c), E.-G. Talbi (c)(d), A.P. Wierzbicki (e) Keywords: Multiple objective programming; Parallel computing; Multiple reference point approach; Evolutionary computations; Bi-objective flow-shop scheduling Abstract: This paper presents a multiple reference point approach for multi-objective optimization problems of discrete and combinatorial nature. When approximating the Pareto Frontier, multiple reference points can be used instead of traditional techniques. These multiple reference points can easily be implemented in a parallel algorithmic framework. The reference points can be uniformly distributed within a region that covers the Pareto Frontier. An evolutionary algorithm is based on an achievement scalarizing function that does not impose any restrictions with respect to the location of the reference points in the objective space. Computational experiments are performed on a bi-objective flow-shop scheduling problem. Results, quality measures as well as a statistical analysis are reported in the paper. Author Affiliation: (a) CEG-IST, Center for Management Studies, Instituto Superior Tecnico, Technical University of Lisbon, Tagus Park, Av. Cavaco Silva, 2780-990 Porto Salvo, Portugal (b) LAMSADE, UMR CNRS 7024, Universite Paris-Dauphine, Place du Marechal De Lattre de Tassigny, 75775 Paris Cedex, France (c) Universite Lille 1, LIFL - CNRS, INRIA Lille-Nord Europe, Parc Scientifique de la Haute Borne, 40 av. Halley, 59650 Villeneuve d'Ascq, France (d) King Saud University, Riyadh, Saudi Arabia (e) National Institute of Telecommunications, Szachowa Str. 1, 04-894 Warsaw, Poland Article History: Received 21 May 2009; Accepted 27 December 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.09.026 Byline: Jose M. Framinan (a), Ruben Ruiz (b) Keywords: Scheduling systems; Architecture; Functional requirements Abstract: This paper deals with the development of customised and realistic manufacturing scheduling systems. More specifically, we focus onto a key element that may help driving their efficient design and implementation: i.e., the set of building blocks that should include a generic scheduling system and its interconnections, a set collectively known as the architecture of a system. To do so, we first analyse existing contributions on the topic together with papers describing different functional requirements of scheduling systems. These contributions are then discussed and classified, and a modular architecture for manufacturing scheduling systems is proposed. This proposal updates, extends and refines the well-known architecture proposed earlier by Pinedo and Yen's [Pinedo, M.L., Yen, B.P.-C., 1997. On the design and development of object-oriented scheduling systems. Annals of Operations Research 70 (1), 359-378], and serves to integrate the different requirements identified in the literature review. Author Affiliation: (a) Industrial Management, School of Engineering, University of Seville, Ave. Descubrimientos s/n, E41092 Seville, Spain (b) Grupo de Sistemas de Optimizacion Aplicada, Instituto Tecnologico de Informatica, Universidad Politecnica de Valencia, Valencia, Camino de Vera s/n, 46021 Valencia, Spain Article History: Received 20 April 2009; Accepted 17 September 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.11.034 Byline: Hamed Samarghandi, Kourosh Eshghi Keywords: Facilities planning and design; Linear ordering problem; Tabu search; Integer programming Abstract: The general goal of the facility layout problem is to arrange a given number of facilities to minimize the total cost associated with the known or projected interactions between them. One of the special classes of the facility layout problem is the Single Row Facility Layout Problem (SRFLP), which consists of finding an optimal linear placement of rectangular facilities with varying dimensions on a straight line. This paper first presents and proves a theorem to find the optimal solution of a special case of SRFLP. The results obtained by this theorem prove to be very useful in reducing the computational efforts when a new algorithm based on tabu search for the SRFLP is proposed in this paper. Computational results of the proposed algorithm on benchmark problems show the greater efficiency of the algorithm compared to the other heuristics for solving the SRFLP. Author Affiliation: Sharif University of Technology, Tehran, Iran Article History: Received 25 September 2008; Accepted 29 November 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.11.029 Byline: Jens Lysgaard Keywords: Routing; Pyramidal traveling salesman; Branch-and-cut-and-price Abstract: This paper introduces the pyramidal capacitated vehicle routing problem (PCVRP) as a restricted version of the capacitated vehicle routing problem (CVRP). In the PCVRP each route is required to be pyramidal in a sense generalized from the pyramidal traveling salesman problem (PTSP). A pyramidal route is defined as a route on which the vehicle first visits customers in increasing order of customer index, and on the remaining part of the route visits customers in decreasing order of customer index. Moreover, this paper develops an exact branch-and-cut-and-price (BCP) algorithm for the PCVRP. A main feature of the algorithm is that exact pricing over elementary routes are done in pseudo-polynomial time. Computational results suggest that PCVRP solutions are highly useful for obtaining near-optimal solutions to the CVRP. Furthermore, pricing of pyramidal routes may prove to be very useful in column generation for the CVRP. Author Affiliation: CORAL, Department of Business Studies, Aarhus School of Business, University of Aarhus, Fuglesangs Alle 4, DK-8210 Aarhus V, Denmark Article History: Received 29 April 2008; Accepted 21 November 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.12.017 Byline: Christopher J. Woodruff Keywords: Multiple criteria analysis; Cost benefit analysis; Purchasing Abstract: It is shown that the design of some inventory structures such as critical protective items for local emergency response elements, or selection of some types of sports team (e.g. baseball, cricket), is appropriately formulated as the selection of an optimal set of options over multiple criteria. This paper examines the problem of defining what might constitute optimum sets under such conditions. Noting that options may be characterised with data of various scale types, the paper introduces a number of different policies for optimality appropriate to the different scale types, and derives closed expressions that implement the various policies. It is shown that simply choosing the best individual options to construct a preferred team is likely to be sub-optimal particularly if the policy is hard to meet. This result is shown to be robust over data structures and data scale types. Managerial implications are briefly considered. Author Affiliation: Human Protection & Performance Division, DSTO, 506 Lorimer St, Fishermans Bend, Victoria 3207, Australia Article History: Received 9 April 2009; Accepted 16 December 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.09.024 Byline: Ruben Ruiz (a), Jose Antonio Vazquez-Rodriguez (b) Keywords: Scheduling; Hybrid flow shop; Review Abstract: The scheduling of flow shops with multiple parallel machines per stage, usually referred to as the hybrid flow shop (HFS), is a complex combinatorial problem encountered in many real world applications. Given its importance and complexity, the HFS problem has been intensively studied. This paper presents a literature review on exact, heuristic and metaheuristic methods that have been proposed for its solution. The paper briefly discusses and reviews several variants of the HFS problem, each in turn considering different assumptions, constraints and objective functions. Research opportunities in HFS are also discussed. Author Affiliation: (a) Grupo de Sistemas de Optimizacion Aplicada, Instituto Tecnologico de Informatica, Universidad Politecnica de Valencia, Valencia, Spain (b) Automated Scheduling, Optimization and Planning Research Group, School of Computer Science, University of Nottingham, Jubilee Campus Wollaton Road, Nottingham NG8 1BB, UK Article History: Received 11 March 2009; Accepted 17 September 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.08.003 Byline: Meryem Duygun Fethi (a), Fotios Pasiouras (b) Keywords: Artificial intelligence; Banks; Data envelopment analysis; Efficiency; Operational research; Literature review Abstract: This paper presents a comprehensive review of 196 studies which employ operational research (O.R.) and artificial intelligence (A.I.) techniques in the assessment of bank performance. Several key issues in the literature are highlighted. The paper also points to a number of directions for future research. We first discuss numerous applications of data envelopment analysis which is the most widely applied O.R. technique in the field. Then we discuss applications of other techniques such as neural networks, support vector machines, and multicriteria decision aid that have also been used in recent years, in bank failure prediction studies and the assessment of bank creditworthiness and underperformance. Author Affiliation: (a) School of Management, University of Leicester, UK (b) School of Management, University of Bath, UK Article History: Received 25 February 2009; Accepted 5 August 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.10.027 Byline: Isabel Correia (a), Luis Gouveia (b), Francisco Saldanha-da-Gama (b) Keywords: Capacitated facility location; Modular link costs; Extended reformulations Abstract: In this paper we study a discretization reformulation technique in the context of a facility location problem with modular link costs. We present a so-called 'traditional' model and a straightforward discretized model with a general objective function whose variable coefficients are computed by solving a simple knapsack problem. We show that the linear programming relaxation of the discretized model dominates the linear programming relaxation of the original model. The discretized model suggests quite intuitive valid inequalities that considerably improve the linear programming relaxation of the original model. Computational results based on randomly generated data show that in the context of problems with modular costs, the proposed discretized models perform significantly better than the 'traditional' models. An important outcome of our research is the result, whose proof is also presented in this paper, that a restricted version of the discretized model gives an extended description of the convex hull of the integer solutions of a subproblem that usually arises in network design problems with modular costs. Author Affiliation: (a) Universidade Nova de Lisboa, Faculdade de CiA*ncias e Tecnologia, Departamento de Matematica, CMA 2829-516 Caparica, Portugal (b) Universidade de Lisboa, Faculdade de CiA*ncias, Departamento de Estatistica e Investigacao Operacional/Centro de Investigacao Operacional, 1749-016 Lisboa, Portugal Article History: Received 12 June 2008; Accepted 28 October 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.07.012 Byline: Aliaksandr Shyshou (a), Irina Gribkovskaia (a), Jaume Barcelo (b) Keywords: Maritime transportation; Discrete-event simulation; Fleet sizing problem; Strategic planning; Oil and gas industry Abstract: A fleet sizing problem arising in anchor handling operations related to movement of offshore mobile units is presented in this paper. Typically, the intensity of these operations is unevenly spread throughout the year. The operations are performed by dedicated vessels, which can be hired either on the long-term basis or on the spot market. Spot rates are frequently a magnitude higher than long-term rates, and vessels are hired on the spot market if there is a shortage of long-term vessels to cover the ongoing anchor handling operations. Deciding the cost-optimal fleet of vessels on the long-term hire to cover future operations is a problem facing offshore oil and gas operators. This decision has a heavy economic impact as anchor handling vessels are among the most expensive ones. The problem is highly stochastic because durations of anchor handling operations vary and depend on uncertain weather conditions. Moreover, future spot rates for anchor handling vessels are extremely volatile. The objective of this paper is to describe a simulation model for the fleet sizing problem. The study was initiated by the largest Norwegian offshore oil and gas operator and has received considerable acceptance among the planners. Author Affiliation: (a) Molde University College, Postbox 2110, N-6402 Molde, Norway (b) Department of Statistics and Operations Research, CENIT, Universitat Politecnica de Catalunya, Campus Nord, Edifici C5, Office 215, Jordi Girona Salgado 1-3, 08034 Barcelona, Spain Article History: Received 10 February 2009; Accepted 11 July 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.07.027 Byline: Benito A. Stradi-Granados (a), Emmanuel Haven (b) Keywords: Interval arithmetic; Interval Gauss-Seidel method; IN/GB method; Rational expectations; Forward-looking macroeconomics models Abstract: The use of interval mathematics to solve non-linear problems is an attractive alternative to traditional real-number techniques. It was demonstrated in a previous paper [Stradi, B., Haven, E., 2005. Optimal investment strategy via interval arithmetic. International Journal of Theoretical and Applied Finance 8(2), 185-205] that interval arithmetic in the form of the Interval-Newton Generalized Bisection (IN/GB) method is effective in solving highly non-linear problems. In this paper we solve a rational expectations models with the help of the IN/GB method. This method is capable of (i) rapidly eliminating no solution sections of the multidimensional space and (ii) concentrate computational efforts on those areas of multidimensional space where there may be a solution. Author Affiliation: (a) Department of Materials Science and Engineering, Institute of Technology of Costa Rica, Cartago, Costa Rica (b) School of Management, University of Leicester, Leicester, United Kingdom Article History: Received 5 January 2009; Accepted 15 July 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.07.032 Byline: Denis Bouyssou (a)(b), Thierry Marchant (c) Keywords: Additive conjoint measurement; Multiple criteria analysis; Sorting; Ordered categories Abstract: Conjoint measurement studies binary relations defined on product sets and investigates the existence and uniqueness of, usually additive, numerical representations of such relations. It has proved to be quite a powerful tool to analyze and compare MCDM techniques designed to build a preference relation between multiattributed alternatives and has been an inspiring guide to many assessment protocols. The aim of this paper is to show that additive representations can be obtained on the basis of much poorer information than a preference relation. We will suppose here that the decision maker only specifies for each object if he/she finds it 'attractive' (better than the status quo), 'unattractive' (worse than the status quo) or 'neutral' (equivalent to the status quo). We show how to build an additive representation, with tight uniqueness properties, using such an ordered partition of the set of objects. On a theoretical level, this paper shows that classical results of additive conjoint measurement can be extended to cover the case of ordered partitions and wishes to be a contribution to the growing literature on the foundations of sorting techniques in MCDM. On a more practical level, our results suggest an assessment strategy of an additive model on the basis of an ordered partition. Author Affiliation: (a) CNRS-LAMSADE, Place du Marechal de Lattre de Tassigny, F-75775 Paris Cedex 16, France (b) Universite Paris Dauphine, Place du Marechal de Lattre de Tassigny, F-75775 Paris Cedex 16, France (c) Ghent University, Department of Data Analysis, H. Dunantlaan, 1, B-9000 Gent, Belgium Article History: Received 20 May 2008; Accepted 17 July 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.07.013 Byline: Jose Villen-Altamirano Keywords: Simulation; Queueing; Rare event probabilities; RESTART Abstract: RESTART is an accelerated simulation technique that allows the evaluation of extremely low probabilities. In this method a number of simulation retrials are performed when the process enters regions of the state space where the chance of occurrence of the rare event is higher. These regions are defined by means of a function of the system state called the importance function. Guidelines for obtaining suitable importance functions and formulas for the importance function of two-stage networks were provided in previous papers. In this paper, we obtain effective importance functions for RESTART simulation of Jackson networks where the rare set is defined as the number of customers in a particular ('target') node exceeding a predefined threshold. Although some rough approximations and assumptions are used to derive the formulas of the importance functions, they are good enough to estimate accurately very low probabilities for different network topologies within short computational time. Author Affiliation: Departamento de Matematica Aplicada, Universidad Politecnica de Madrid, Calle Arboleda s/n, 28031-Madrid, Spain Article History: Received 31 July 2008; Accepted 23 July 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.06.004 Byline: Mohsen Jahangirian (a), Tillal Eldabi (b), Aisha Naseer (a), Lampros K. Stergioulas (a), Terry Young (a) Keywords: Simulation; System dynamics; Modelling methods; Business and manufacturing Abstract: This paper reports the results of a review of simulation applications published within peer-reviewed literature between 1997 and 2006 to provide an up-to-date picture of the role of simulation techniques within manufacturing and business. The review is characterised by three factors: wide coverage, broad scope of the simulation techniques, and a focus on real-world applications. A structured methodology was followed to narrow down the search from around 20,000 papers to 281. Results include interesting trends and patterns. For instance, although discrete event simulation is the most popular technique, it has lower stakeholder engagement than other techniques, such as system dynamics or gaming. This is highly correlated with modelling lead time and purpose. Considering application areas, modelling is mostly used in scheduling. Finally, this review shows an increasing interest in hybrid modelling as an approach to cope with complex enterprise-wide systems. Author Affiliation: (a) School of Information Systems, Computing and Mathematics, Brunel University, Uxbridge, Middlesex UB8 3PH, UK (b) Brunel Business School, Brunel University, Uxbridge, Middlesex UB8 3PH, UK Article History: Received 17 October 2008; Accepted 5 June 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.06.033 Byline: Nguyen Huynh Tuong, Ameur Soukhal, Jean-Charles Billaut Keywords: Scheduling; Single machine; Parallel machines; Dynamic programming Abstract: This paper deals with a scheduling problem of independent tasks with common due date where the objective is to minimize the total weighted tardiness. The problem is known to be ordinary NP-hard in the case of a single machine and a dynamic programming algorithm was presented in the seminal work of Lawler and Moore [E.L. Lawler, J.M. Moore, A functional equation and its application to resource allocation and sequencing problems, Management Science 16 (1969) 77-84]. In this paper, this algorithm is described and discussed. Then, a new dynamic programming algorithm is proposed for solving the single machine case. These methods are extended for solving the identical and uniform parallel-machine scheduling problems. Author Affiliation: Laboratoire d'Informatique, Universite Francois Rabelais, Tours 64 Avenue Jean Portalis - 37200 Tours, France Article History: Received 29 July 2008; Accepted 22 June 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.06.028 Byline: Maryam Ehsani (a), Ahmad Makui (a), Soheil Sadi Nezhad (b) Keywords: Distributed decision network; Informational complexity of decision network; Shannon entropy; U uncertainty in possibility theory Abstract: This paper assumes the organization as a distributed decision network. It proposes an approach based on application and extension of information theory concepts, in order to analyze informational complexity in a decision network, due to interdependence between decision centers. Based on this approach, new quantitative concepts and definitions are proposed in order to measure the information in a decision center, based on Shannon entropy and its complement in possibility theory, U uncertainty. This approach also measures the quantity of interdependence between decision centers and informational complexity of decision networks. The paper presents an agent-based model of organization as a graph composed of decision centers. The application of the proposed approach is in analyzing and assessing a measure to the organization structure efficiency, based on informational communication view. The structure improvement, analysis of information flow in organization and grouping algorithms are investigated in this paper. The results obtained from this model in different systems as distributed decision networks, clarifies the importance of structure and information distribution sources effect's on network efficiency. Author Affiliation: (a) Industrial Engineering Dept., Iran University of Science and Technology, Tehran, Narmak 1684613114, Iran (b) Industrial Engineering Dept., Science and Research Branch Islamic Azad University (SRBAIU), Tehran 1477893855, Iran Article History: Received 7 October 2007; Accepted 29 June 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.05.010 Byline: Fredrik Olsson, Patrik Tydesjo Keywords: Inventory control; Perishable items; Stochastic Abstract: Our model deals with a single-product and a single-stock location with Poisson demand. The replenishment leadtime from the external supplier is fixed. The lifetime of the product is also fixed, and aging is assumed to begin when the order is placed. When the age of a unit has reached its lifetime, the unit is useless and thus discarded from the system. The replenishment policy is assumed to be an order-up-to S-policy. Demand that cannot be met immediately is backordered. We consider three different cases where the service requirements are represented by: (1) backorder costs per unit, (2) a service level constraint, (3) backorder costs per unit and time unit. Cases 1 and 2 are solved exactly, while an approximation is developed for case 3. We show how the results from an earlier paper assuming lost sales can be used to solve the considered problems. Our results are compared to the results in a related paper considering (Q, r)-policies. Author Affiliation: Department of Industrial Management and Logistics, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden Article History: Received 8 November 2006; Accepted 11 May 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.04.009 Byline: Shaoxiang Chen (a), Guillermo Gallego (b), Michael Z.F. Li (a), Bing Lin (c) Keywords: Dynamic programming; Yield/revenue management; Optimal booking policies; Switching curves Abstract: In this paper, we study a two-flight model where there are two flights between two cities in a day (e.g., one departs at 9:00am and another at 11:00am) and booking requests in each fare class arrive according to a random process. There are three types of booking requests: the first and second types are respectively for the first and the second flight only; whereas the third type is flexible and willing to take either flight. Upon receiving a booking request, the airline has to decide whether to accept it, and in case a third type is accepted, which flight to accommodate it. This paper uncovers the structure of optimal booking policies through four monotone switching curves. We also present an extension of the basic model to multiple-flight case. Finally, a numerical example is used to illustrate the derivation and the dynamics of the optimal booking policies. Author Affiliation: (a) Division of Information Technology and Operations Management, Nanyang Business School, Nanyang Technological University, Nanyang Avenue, Singapore 639798, Singapore (b) Department of Industrial Engineering and Operations Research, Columbia University, New York City, NY 10027, USA (c) Department of Management Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong Article History: Received 26 August 2008; Accepted 16 April 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.03.032 Byline: Maria Psillaki (a), Ioannis E. Tsolas (b), Dimitris Margaritis (c) Keywords: G21 Abstract: This paper investigates whether productive inefficiency measured as the distance from the industry's 'best practice' frontier is an important ex-ante predictor of business failure. We use samples of French textiles, wood and paper products, computers and R&D companies to obtain efficiency estimates for individual firms in each industry. These efficiency measures are derived from a directional technology distance function constructed empirically using non-parametric data envelopment analysis (DEA) methods. Estimating binary and ordered logit regression models we find that productive efficiency has significant explanatory power in predicting the likelihood of default over and above the effect of standard financial indicators. Author Affiliation: (a) University of Nice-Sophia Antipolis, GREDEG-CNRS, 250 rue A. Einstein, 06560 Valbonne, France (b) National Technical University of Athens, School of Applied Mathematics and Physics, 9 Iroon Polytechniou, Zografou Campus, Athens 157 80, Greece (c) Department of Finance, Faculty of Business, AUT, 42 Wakefield St., Auckland 1010, New Zealand Article History: Received 11 January 2008; Accepted 24 March 2009 Article Note: (footnote) [star] We would like to thank two anonymous referees for helpful and insightful comments and the Editor for his guidance and encouragement.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.04.012 Byline: Kankana Mukherjee Keywords: Data Envelopment Analysis; Directional distance function; Energy efficiency; Indian manufacturing; OR in energy Abstract: In recent years the Indian economy has achieved a rapid growth rate. However, one of the challenges facing the economy is the large energy supply that would be needed to sustain this growth path. Hence attaining energy efficiency is crucial for the economy. This paper examines the Indian manufacturing sector and utilizes a variant of the directional distance function to obtain comprehensive measures of performance of the major manufacturing states, given the joint goals of achieving energy conservation and output growth. The results of the empirical application reveal that given the prevailing technology, the average manufacturing firm across the states could reduce energy input and increase output simultaneously by an annual average of 3.84%, by improving technical efficiency. To accommodate a larger simultaneous increase in output and reduction in energy use, India should adopt superior technologies so as to shift the efficient frontier outward. Author Affiliation: Department of Management, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA Article History: Received 9 January 2008; Accepted 16 April 2009 Article Note: (footnote) [star] The paper has benefited from valuable comments received from participants at the 2007 INFORMS Annual Meeting as well as three anonymous referees of this journal.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.04.011 Byline: Brecht Cardoen (a)(b), Erik Demeulemeester (b), Jeroen BeliA'n (b)(c) Keywords: OR in health services; Operating room; Scheduling; Planning; Literature review Abstract: This paper provides a review of recent operational research on operating room planning and scheduling. We evaluate the literature on multiple fields that are related to either the problem setting (e.g., performance measures or patient classes) or the technical features (e.g., solution technique or uncertainty incorporation). Since papers are pooled and evaluated in various ways, a diversified and detailed overview is obtained that facilitates the identification of manuscripts related to the reader's specific interests. Throughout the literature review, we summarize the significant trends in research on operating room planning and scheduling, and we identify areas that need to be addressed in the future. Author Affiliation: (a) Vlerick Leuven Gent Management School, Operations and Technology Management Center, Reep 1, B-9000 Gent, Belgium (b) Katholieke Universiteit Leuven, Faculty of Business and Economics, Department of Decision Sciences and Information Management, Naamsestraat 69, B-3000 Leuven, Belgium (c) Hogeschool-Universiteit Brussel, Campus Economische Hogeschool, Centrum voor Modellering en Simulatie, Stormstraat 2, B-1000 Brussel, Belgium Article History: Received 6 May 2008; Accepted 17 April 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2009.03.051 Byline: Yanfeng Ouyang, Xiaopeng Li Keywords: Supply chain management; Network; The bullwhip effect; Frequency domain analysis Abstract: This paper analyzes the propagation and amplification of order fluctuations (i.e., the bullwhip effect) in supply chain networks operated with linear and time-invariant inventory management policies. The supply chain network is allowed to include multiple customers (e.g., markets), any network structure, with or without sharing information. The paper characterizes the stream of orders placed by any supplier for any stationary customer demand processes, and gives exact formulas for the variance of the orders placed and the amplification of order fluctuations. The paper also derives robust analytical conditions, based only on inventory management policies, to predict the presence of the bullwhip effect for any network structure, any inventory replenishment policies, and arbitrary customer demand processes. Numerical examples show that the analytical results accurately quantify the bullwhip effect; managerial insights are drawn from the analysis. The methodology presented in this paper generalizes those in previous studies for serial supply chains. Author Affiliation: Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States Article History: Received 3 June 2007; Accepted 31 March 2009