bluuebunny/crossref_metadata_2025 huggingface dataset:
Trade‐Offs in JIT Production Planning for Multi‐Stage Systems: Balancing Work‐Load Variations and WIP Inventories
Authors: Houghton E. , Portougal V.
Published: August 2006

Production planning for flow shops, job shops and projects has attracted much attention in the OR literature. This is not so for the comparatively new production environment of post‐mass production, wherein a variety of end‐product models is produced on high productivity equipment. As this production environment becomes increasingly dominant in many countries with small markets like Australia and New Zealand, there is a growing urgency for an OR analysis of its complex planning and scheduling problems, This paper presents a planning procedure for balancing workload variations and WIP inventories for an existing multi‐stage processing facility in a post‐mass production environment with discrete planning periods. The methodology is based on a multi‐criteria production planning model which allows the facility to move towards JIT‐processing at each processing stage without a full JIT commitment for the facility.
A Fuzzy Approach to Preference Structure in Multicriteria Ranking
Authors: Radojevic A. , Petrovic S. , Radojevic D.
Published: August 2006

The family of Promethee methods for multicriteria ranking of a finite set of alternatives is well known in literature and used in practice. In order to express her/his preference structure the decision maker is asked to select, for each criterion, a preference function from a predefined set. It is a function that maps differences between criterion values of pairs of alternatives into interval [0,1]. For each preference function, the decision maker has to fix parameters that define indifference and strict preference areas.

A weak point in Promethee methods is that imprecision in judgment of preference functions is handled by relatively simple and rigid mathematical artifacts. We propose fuzzy sets theory and associate approximate reasoning as an appropriate framework to imitate human reasoning in expressing a preference structure. For each criterion, the decision maker uses linguistic terms ‘small difference’, ‘medium difference’, and ‘big difference’, which enable him/her to express his/her preference structure in a linguistic and thus more natural way. These descriptors interpret the system of decision maker's values and are context dependent. We introduce fuzzy IF‐THEN rules that relate the difference of criterion values to the preference function. The proposed modification extends the applicability of Promethee methods significantly, because it enables ranking of alternatives in the case when criteria values are fuzzy variables. The corresponding software is developed and tested on a number of examples.
Common Action and Electricity Trade in Northern Europe
Authors: Larsson T. , Grohnheit P. Erik , Unander F.
Published: August 2006

Common action (CA) increases the possibilities to adapt to restrictions on CO2 emissions. In this paper the value of common action is quantified for Denmark, Norway and Sweden using a systems engineering model, MARKAL. Electricity trade as a means for CA is studied in more detail.
On the General Utility of Discounted Markov Decision Processes
Authors: Kadota Y. , Kurano M. , Yasuda M.
Published: August 2006

We will discuss an expected utility of rewards which are generated by Markov decision processes. This is applied to the optimal stopping problem with a utility treatment. Also a combined model of the decision processes and the stopping problem, called a stopped Markov decision, is considered under the utility.
On Locating a Semi‐desirable Facility on the Continuous Plane
Authors: Brimberg J. , Juel H.
Published: August 2006

The paper considers a bicriteria model for locating a semi‐desirable facility on the plane. One criterion is that of minimizing the sum of weighted distances between customers and facility, where distances are given by an arbitrary norm. The other criterion is that of maximizing the weighted Euclidean distance from the facility to the closest customer. The objective is to generate the set of efficient points, from which the decision maker must choose the preferred one. Two reformulations are considered: in one, the sum of weighted distances is minimized, subject to constraints requiring that each customer must have a weighted Euclidean distance to the facility of at least a given parameter; varying the parameter yields the efficient set. In the other, both criteria are viewed as minimization problems and a convex combination of them is minimized. Properties of the reformulations are given, and the reformulations are compared. Finally, a solution procedure is outlined.
A Neighbourhood‐based Hybrid Method for Scheduling with Fuzzy Due‐dates
Authors: Adamopoulos G.I. , Pappis C.P.
Published: August 2006

In this paper, the single machine scheduling problem with fuzzy due‐dates and controllable processing times is dealt with. The objective is to maximize the “grade of satisfaction” incurred, subject to a total processing cost constraint. The former is a function of the deviations of the jobs completion times from their most desirable due dates. The latter is considered to be a linear function of the jobs compression. The problem is solved via a heuristic approach, which encapsulates concepts from Tabu Search, Genetic Algorithms and Simulated Annealing. Both Complete Enumeration and Branch and Bound techniques are used to evaluate the efficiency of the proposed method.
Measuring Service Quality in the Process of Delivering a Simulation Study: The Customer's Perspective
Authors: Robinson S.
Published: August 2006

Little research has been performed into the assessment of simulation models and even less into the assessment of simulation studies. The purpose of this paper is to describe an instrument (known as SimQual) that has been developed to assess the quality of a simulation study in which the customers are highly involved. The instrument is founded on the principles of quality measurement, and in particular service quality. From the perspective that a simulation project is a service, delivered by providers to customers, it is argued that the customers' quality perceptions are based not only on the outcome of the work (technical quality), but also on the way in which the project is delivered (functional quality). Through a series of interviews with providers and customers a set of technical and functional factors have been identified that relate to the quality of a simulation study. Based on these factors the SimQual instrument has been developed to measure simulation project quality. The paper concludes by reporting the results of empirical tests with the instrument and discussing its application as well as areas for further research.
Modelling of Optimal Expansion of a Fuzzy Competence Set
Authors: Wang H‐F. , Wang C.H.
Published: August 2006

A Competence Set, which is a Habitual Domain (HD), is a collection of knowledge and skills. We use these knowledge and skills to solve problems. Based on the concept of fuzzy set theory, this study proposes a method to find an optimal process to expand one's competence set. This process presents an expansion order and by a directed graph, the optimal path of expansion at each stage can be found by a proposed model. This model is a minimization form constrained by max‐product fuzzy relation inequalities. With this model, not only the compound skills can be considered, but also the levels of the acquired skills to solve a problem can be described. Theoretical support is accompanied by an illustrative example.
A DSS For Modelling Logistic Chains in Freight Transport Policy Analysis
Authors: Tavasszy L.A. , Smeenk B. , Ruijgrok C.J.
Published: August 2006

As the logistics activities of firms are becoming increasingly dynamic and global in nature, private and public decision makers depend more and more on information regarding the expected development of future freight flows. A newly developed Decision Support System (DSS) called SMILE (Strategic Model for Integrated Logistic Evaluations) produces forecasts of freight flows related to the Netherlands for a large number of products and modes of transport. The underlying model describes logistics chains at three levels: production, inventory and (multimodal) transportation. The second level accounts for warehousing by using integrated cost functions comprising handling, stockholding and transport costs, using a new segmentation of goods according to their logistical requirements. By means of a graphical user interface, the DSS assists the user with designing scenarios for simulations up to 25 years ahead and visualises the impacts of policy measures on freight flows and the environment. This paper describes the theory behind the model, characteristics of the DSS and potential policy applications.
Simulation of Railway Traffic Control
Authors: Weits E.A.G.
Published: August 2006

Traffic control is the centre of the railway traffic system. The success of a railway traffic simulation model depends very much on an adequate modelling of the traffic control. The main objective of a traffic control system is to minimise delays. Important tasks which contribute to this goal are controlling connections between trains, deciding about priorities and controlling the rotations of crew and rolling stock. In this paper, we discuss a simulation model of railway traffic which is centred around the traffic control functions. It is observed that an object‐oriented approach to the modelling of traffic control presents itself as very natural. It results in a very flexible model, which can accomodate a range of present and future traffic control systems. Finally, we present some results of a simulation study that investigates the possibility of partially automating traffic control.
Supply Chain Management in Food Chains: Improving Performance by Reducing Uncertainty
Authors: van der Vorst J.G.A.J. , Beulens A.J.M. , de Wit W. , van Beek P.
Published: August 2006

This paper investigates the impact of Supply Chain Management on logistical performance indicators in food supply chains. From a review of quantitative and more qualitative managerial literature, we believe that Supply Chain Management should be concerned with the reduction or even elimination of uncertainties to improve the performance of the chain. The following clusters of sources of uncertainty are identified: order forecast horizon, input data, administrative and decision processes and inherent uncertainties. For each source of uncertainty, several improvement principles are identified. A case study was conducted in a food chain in which a simulation model helped quantify the effects of alternative configurations and operational management concepts. By comparing this simulation study with a pilot study, the model is validated against real data, and organisational consequences are identified. The results of the case study suggest that reduction of uncertainties can improve service levels significantly, although current supply chain configurations restrict possible benefits. The availability of real‐time information systems is found to be a requirement for obtaining efficient and effective Supply Chain Management concepts.
Operations Management of Distribution Centers for Vegetables and Fruits
Authors: Broekmeulen R.A.C.M.
Published: August 2006

We present a tactical decision model that improves the effectiveness of the operations of a distribution center for vegetables and fruits. The operations are complicated in the case of vegetables and fruits due to the seasonal fluctuations in production and demand and the need for special storage conditions for different products. Using the decision model we determine an assignment plan, based on historical data. The assignment plan is used at the operational level for storage advice. We used local search techniques to find an assignment plan. The effect of the assignment plan on several storage policies was examined with a simulation model of the operations in the distribution center. The developed model and algorithms are integrated in a PC‐based decision support system.
Multi‐compartment Distribution in the Catering Supply Chain
Authors: Jansen D.R. , van de Vorst G.A.L. , van Weert A.
Published: August 2006

Multi‐compartment distribution can lead to significant cost reductions and environmental savings. In the Dutch catering supply chain lead times have to become shorter, the delivery frequency needs to increase and the product and process quality must improve to meet new and strict food safety regulations (HACCP). To anticipate these market developments a high quality and efficient distribution system is necessary. Therefore, it is necessary to have knowledge and insight regarding the logistics of delivering fresh produce, other chilled products, dry groceries and frozen products in one consignment to caterers. First, the current logistic performance of the Dutch catering chain was analysed and performance indicators and logistic scenarios were formulated. Then, a model was built for the simulation of these logistic scenarios. The two most promising alternative scenarios for all supply chain partners were tested in a real‐life situation. The outcome of this pilot was used to validate and refine the model.
Efficient Solution of a Multi‐commodity, Two‐stage Distribution Problem with Constraints on Assignment of Customers to Distribution Centres
Authors: Hindi K.S. , Basta T. , Pieńkosz K.
Published: August 2006

A two‐stage, distribution‐planning problem is addressed. Customers are to be served with different commodities from a number of plants, through a number of intermediate distribution centres (DCs). The possible locations for the DCs are given. For each location, there is a fixed cost for opening the DC concerned, as well as an operating cost and a maximum capacity. The demand of each customer for each commodity is known, as well as shipping costs throughout. There are also two additional important requirements. First, each customer must be served with all the products it requires from a single distribution centre. Secondly, it must be possible to ascertain the plant origin of each product quantity delivered. The objective is to choose the locations for opening DCs such that the total cost is minimised. The problem is modelled as a mixed‐integer‐programming problem and solved by branch and bound. Lower bounds are calculated through a series of structural transformations. Much of the power of the solution scheme also stems from frequent generation of good upper bounds. Results of extensive computational experiments are given and discussed.
A Lagrangean Approach to Network Design Problems
Authors: Holmberg K. , Yuan D.
Published: August 2006

Network design is a very important issue in the area of telecommunications and computer networks, where there is a large need for construction of new networks. This is due to technological development (fiber optics for telecommunication) and new ways of usage (Internet for computer networks). Optimal design of such networks requires formulation and solution of new optimization models. In this paper, we formulate several fixed charge network design models, capacitated or uncapacitated, directed or undirected, possibly with staircase costs, and survivability requirements. We propose a common solution approach for all these problems, based on Lagrangean relaxation, subgradient optimization and primal heuristics, which together form a Lagrangean heuristic. The Lagrangean heuristic can be incorporated into a branch‐and‐bound framework, if the exact optimal solution must be found. The approach has been tested on problems of various structures and sizes, and computational results are presented.
Stochastic User Equilibrium Traffic Assignment with Turn‐delays in Intersections
Authors: Nielsen O.A. , Frederiksen R.D. , Simonsen N.
Published: August 2006

Turn‐delays in intersections contribute significantly to travel times and thus route choices in urban networks. However, turns are difficult to handle in traffic assignment models due to the asymmetric Jacobian in the cost functions. The paper describes a model where turn delays have been included in the solution algorithm of Stochastic User Equilibrium (SUE) traffic assignment. When the Jacobian is symmetric, SUE minimises the road users' ‘perceived travel resistances’. This is a probit‐model where the links cost‐functions of the links are traffic dependent. Hereby, overlapping routes are handled in a consistent way. However, no theoretical proof of convergence has been given if the Jacobian is asymmetric, although convergence can be shown probable for model data representing realistic road‐networks. However, according to the authors knowledge SUE with intersection delays have not been tested earlier on a full‐scale network. Therefore, an essential part of the paper presents practical tests of convergence. Both geometric delays and delays caused by other turns are considered for each turn. Signalised and non‐signalised intersections are handled in different ways, as are roundabouts. In signalised intersections a separate model handles queues longer than one green‐period. Green‐waves can also be taken into consideration. The model has been tested on a large‐scale network for Copenhagen with good results. To make it possible to establish the comprehensive data, a GIS‐based ‘expert system’ was implemented (see Nielsen, O.A., Frederiksen, R. D. and Simonsen, N. (1997). Using expert system rules to establish data on intersections and turns in road networks. International Transactions in Operational Research, 5, 513–529.
Information effects on commuters' behavior under varying network patronage
Authors: Sinuany‐Stern Z. , Stern E. , Spharadi Z.
Published: August 2006

The present paper presents one aspect of a more comprehensive study which estimated the possible effects of information presented to commuting drivers on their choice behavior, and thus on the whole network performance. This research shows that the contribution of congestion‐related information decreases as the number of drivers using the information increases, the effect of information on behavioral decisions is examined here in relation to network performance.
A framework for developing a daily activity and multimodal travel planner
Authors: Vaughn K.M. , Abdel‐Aty M.A. , Kitamura R.
Published: August 2006

There is a need to further explore ways to use Advanced Traveler Information Systems (ATIS) to encourage transit and ridesharing. One mechanism is to provide convenient travel itinerary information, not just for one trip, but for a day's travel. The formulation should consider time constraints, activity needs, real transit service parameters and the actual street system. Basic algorithmic development is needed to spur the private sector interest in such a product by demonstrating its utility. The activity travel planner will aid its user in planning his daily itinerary by arranging the sequence of stops, suggesting and possibly selecting stop locations, providing transit route and schedule information, and suggesting travel routes. This paper develops a framework for solving the Travel Itinerary Planning Problem (TIPP) which is a variant of the Traveling Salesman Problem (TSP). Implementation of the solution algorithm would be used to develop and test a prototype for an activity and travel planner.
Simulation assisted design and assessment of vehicle guidance systems
Authors: Barceló J. , Ferrer J.L. , Martín R.
Published: August 2006

This paper presents the description and results obtained using prototypes of two simulators purposely built to assist the design and assessment of vehicle guidance systems, namely those based on cellular radio communication technology. These tools have been used to examine the benefits of dynamic route guidance systems compared to static ones, to investigate the stability of the recommended routes with respect to changes in link travel times, the efficiency of the data collection procedures from the equipped vehicles, and the overheads on the telecommunications channels.
Experiential learning activities in Operations Management
Authors: Ammar S. , Wright R.
Published: August 2006

This paper describes eight in‐class activities that have been effectively used to complement the traditional theoretical presentation in an introductory operation and production management course in either an undergraduate or graduate program. For each activity we include the course topics the activity supports, a description of the activity and an evaluation of its effectiveness based on our experience. The activities include physically played games as well as computer simulations. Most are easily adaptable to different courses and teaching styles.
An energy planning approach based on mixed 0–1 Multiple Objective Linear Programming
Authors: Mavrotas G. , Diakoulaki D. , Papayannakis L.
Published: August 2006

Multiple Objective Linear Programming (MOLP) models have been widely used in the energy sector for taking into account several conflicting objectives pursued in energy planning. However, continuous variables are not suffcient to accurately represent discrete phenomena encountered in many practical decision situations, such as the power generation expansion problem. This paper presents a new approach based on a mixed 0–1 MOLP model and applied to the Greek electricity generation sector for identifying the number and output of each type of power units needed to satisfy the expected electricity demand in the future. The core of the model is a branch and bound algorithm, which has been properly modified for the multi‐objective case and is capable of generating the whole set of effcient solutions. The results provided by this method is the extraction of the effcient combinations of the power generation units, and for each combination the effcient solutions determining electricity production from each unit.
Time–cost evaluation of alternative system/process designs
Authors: Shaftel T.L. , Wilson B.M.
Published: August 2006

Techniques for representing system/process designs are a common feature of most design methodologies. These techniques can be enhanced to provide valuable information regarding a specific design structure's trade‐off between task completion times and cost. In this paper, we present a mathematical model and a solution algorithm which can be used to upgrade any well‐structured representation technique to provide this trade‐off. Having this information readily available allows a design team to focus on less quantifiable features of specific designs, thereby improving the overall design process.
IA supported synchronous digital hierarchy transport network planning
Authors: Romão Cavati C.
Published: August 2006

This paper introduces a methodology for carrying out Transport Networks Synchronous Digital Hierarchy (TN‐SDH) planning, when the objective is the definition of routing fiber optics cables in existing galleries. The proposed methodology employs mathematical programming models in which the traffic matrix is represented by means of fuzzy set concepts, its uncertainties considered due to the existence of various and sophisticated telecommunication services in its networks. The TN‐SDH planning is understood as a problem of multicommodity flow networks and the model obtained has a fuzzy linear programming characteristic. This procedure was applied in a large‐scale realistic network and the results show that it is a method which is more attractive than others and do not employ fuzzy set in modeling the knowledge of traffic matrix.
The effectivity of new traffic‐technologies and transportation‐systems in suburban areas and on motorways
Authors: Ludmann J. , Neunzig D. , Weilkes M. , Wallentowitz H.
Published: August 2006

At the Forschungsgesellschaft Kraftfahrwesen mbH Aachen (fka) the submicroscopic traffic simulation program PELOPS (Program for the dEvelopment of Longitudinal micrOscopic traffic Processes in a Systemrelevant environment) was developed in co‐operation with the BMW AG. It simulates the traffic flow on motorways with a specific view on vehicle affairs. One application for PELOPS was the assessment of ACC (Adaptive Cruise Control) systems inside the PROMETHEUS program. A new research period extends the use of ACC about the functionality to urban areas. This requires an extension of PELOPS to include some specific models. With this extension, it is possible to analyse new traffic technologies for individual vehicles or infrastructure. Based on detailed traffic measurements, different scenarios are simulated to improve the traffic flow and to relieve the environment. These scenarios include ACC systems, inter‐vehicle‐communication and intelligent traffic lights. Another actual application is the analysis of the influence of new road trains (extra‐long trucks with increased speed and enhanced breaking‐capabilities) on traffic‐flow and driving safety on German motorways. The paper gives detailed information about the simulation techniques and the results of the current analysis.
Optimal fleet design in a ship routing problem
Authors: Fagerholt K.
Published: August 2006

The problem of deciding an optimal fleet (the type of ships and the number of each type) in a real liner shipping problem is considered. The liner shipping problem is a multi‐trip vehicle routing problem, and consists of deciding weekly routes for the selected ships. A solution method consisting of three phases is presented. In phase 1, all feasible single routes are generated for the largest ship available. Some of these routes will use only a small portion of the ship's capacity and can be performed by smaller ships at less cost. This fact is used when calculating the cost of each route. In phase 2, the single routes generated in phase 1 are combined into multiple routes. By solving a set partitioning problem (phase 3), where the columns are the routes generated in phases 1 and 2, we find both the optimal fleet and the coherent routes for the fleet.
Job sequencing with uncertain and controllable processing times
Authors: Adamopoulos G.I. , Pappis C.P. , Karacapilidis N.I.
Published: August 2006

In this paper, a single machine scheduling problem is considered. The jobs' processing times are controllable (i.e., they may take any value within a certain range) and non‐precisely defined. They are treated as linguistic variables, whose values are expressed by means of fuzzy numbers. The objective function to be minimised is: (a) the mean flow time cost plus the mean processing cost, and (b) the maximum flow time cost plus the total processing cost. The problem is modelled as an assignment problem and is solved optimally with respect to the defuzzification strategy used.
Towards hybrid evolutionary algorithms
Authors: Preux P. , Talbi E.‐G.
Published: August 2006

Metaheuristics have received considerable interest these recent years in the field of combinatorial optimization. However, the choice of a particular algorithm to optimize a certain problem is still mainly driven by some sort of devotion of its author to a certain technique rather than by a rationalistic choice driven by reason. Hybrid algorithms have shown their ability to provide local optima of high quality. Hybridization of algorithms is still in its infancy: certain combinations of algorithms have experimentally shown their performance, though the reasons of their success is not always really clear. In order to add some rational to these issues, we study the structure of search spaces and attempt to relate it to the performance of algorithms. We wish to explain the behavior of search algorithms with this knowledge and provide guidelines in the design of hybrid algorithms. This paper briefly reviews the current knowledge we have on search spaces of combinatorial optimization problems. Then, we discuss hybridization and present a general classification of the way hybridization can be conducted in the light of our knowledge of the structure of search spaces.
A self‐organizing neural network approach for multiple traveling salesman and vehicle routing problems
Authors: Modares A. , Somhom S. , Enkawa T.
Published: August 2006

This paper addresses several algorithms based on self‐organizing neural network approach for routing problems. The algorithm for Traveling Salesman Problem is elaborated and the extension of the proposed algorithm to more complex problems namely, Multiple Traveling Salesmen and Vehicle Routing is discussed. In order to investigate the performance of the algorithms, a comprehensive empirical study has been provided. The simulations, which are conducted on standard data, evaluate the overall performance of this approach by comparing the results with the best known or the optimal solutions of the problems. The proposed algorithm shows significant advances in both qualities of the solution and computational efforts for most of the experimented data.
Approximating minimum spanning tree of depth 2
Authors: Alfandari L. , Paschos V.T.
Published: August 2006

We prove that the problem of finding, in an undirected graph with non‐negative costs on edges, a minimum cost rooted spanning tree of depth 2 is NP‐hard. We then prove that, in a graph of ordern, this problem cannot be approximated within better thanO)lnn), unless problems in NP can be solved by slightly superpolynomial algorithms. We also prove that the metric version of the problem is MAX‐SNP‐hard and, consequently, cannot be approximated by polynomial time approximation schemes, unless P=NP. We devise approximation algorithms for several restricted cases and, finally, a polynomial time algorithm approximating the general problem within ratio lnn.
An adaptive tabu search algorithm for the capacitated clustering problem
Authors: França P.M. , Sosa N. M. , Pureza V.
Published: August 2006

In the Capacitated Clustering Problem, a given set of customers with distinct demands must be partitioned into p clusters with limited capacities. The objective is to find p customers, called medians, from which the sum of the distances to all other customers in the cluster is minimized. In this article, a new adaptive tabu search approach is applied to solve the problem. Initial solutions are obtained by four constructive heuristics that use weights and distances as optimization criteria. Two neighborhood generation mechanisms are used by the local search heuristic: pairwise interchange and insertion. Computational results from 20 instances found in the literature indicate that the proposed method outperforms alternative metaheuristics developed for solving this problem.
Solving multiple objective quasi‐convex goal programming problems by linear programming
Authors: Li H‐L. , Yu C‐S.
Published: August 2006

This study presents a novel means of resolving multiple objective goal programming (GP) problems with quasi‐convex linear penalty functions. The proposed method initially expresses a quasi‐convex function by the maximum operator of two convex functions, then solves it via a linear programming technique. The proposed method does not contain any zero–one variables; nor does it require dividing the multi‐objective quasi‐convex GP problem into large sub‐problems as in conventional methods. Some illustrative examples are provided.
Classical and modern heuristics for the vehicle routing problem
Authors: Laporte G. , Gendreau M. , Potvin J‐Y. , Semet F.
Published: August 2006

This article is a survey of heuristics for the Vehicle Routing Problem. It is divided into two parts: classical and modern heuristics. The first part contains well‐known schemes such as, the savings method, the sweep algorithm and various two‐phase approaches. The second part is devoted to tabu search heuristics which have proved to be the most successful metaheuristic approach. Comparative computational results are presented.
Very large‐scale neighborhood search
Authors: Ahuja R.K. , Orlin J.B. , Sharma D.
Published: August 2006

Neighborhood search algorithms are often the most effective approaches available for solving partitioning problems, a difficult class of combinatorial optimization problems arising in many application domains including vehicle routing, telecommunications network design, parallel machine scheduling, location theory, and clustering. A critical issue in the design of a neighborhood search algorithm is the choice of the neighborhood structure, that is, the manner in which the neighborhood is defined. Currently, the two‐exchange neighborhood is the most widely used neighborhood for solving partitioning problems. The paper describes the cyclic exchange neighborhood, which is a generalization of the two‐exchange neighborhood in which a neighbor is obtained by performing a cyclic exchange. The cyclic exchange neighborhood has substantially more neighbors compared to the two‐exchange neighborhood. This paper outlines a network optimization based methodology to search the neighborhood efficiently and presents a proof of concept by applying it to the capacitated minimum spanning tree problem, an important problem in telecommunications network design.
Analysis of a ring‐based loss network
Authors: Thompson M.
Published: August 2006

Loss networks are a class of resource allocation models which have proved useful in the study and design of communication networks. A major aim when analysing these models is to obtain measures of performance such as congestion probabilities and throughput. Even for moderately sized networks it is often not possible to calculate the quantities of interest exactly in reasonable time. Accordingly there is motivation to investigate methods of accurate approximation. This paper is concerned with estimating the performance measures of a ring‐shaped network with branches. Two methods are presented: an asymptotic analysis made possible by the network's cyclic structure, and a technique utilising the network's symmetry which could be applied more generally.
Heuristic approaches to the asymmetric travelling salesman problem with replenishment arcs
Authors: Mak V. , Boland N.
Published: August 2006

The Asymmetric Travelling Salesman Problem with Replenishment Arcs (RATSP) is a new class of problem arising from work related to aircraft routing. This paper describes the problem and presents heuristic approaches for solving the RATSP. We use simulated annealing to obtain feasible solutions, and hence, upper bounds on the optimum value, and solve a Lagrangean dual problem using a subgradient optimization method to obtain lower bounds. While previous methods failed to obtain optimal solutions to some problem classes after 2 h of computation time, with average gaps ranging from 15% to 30%, our heuristic approaches take only 15–20 min to obtain feasible solutions, with gaps of less than 3%. We give computational results comparing these approaches.
Simulation in public sector management: a case study
Authors: Hays M‐A. , Bebbington M.
Published: August 2006

We detail the development and application of a simulation model to aid decision making concerning the procedures followed in the Office of Film and Literature Classification, by forecasting the effects of possible management initiatives. The major variables are — the number of censors, the volume of publications to be classified (with special emphasis on computer technology publications) and the procedures, in particular, the number of censors with decision‐making powers. A model of the system was developed using Extend; a simulation software package designed to aid decision support. This model was used to investigate the utilization of “decision‐makers”, and to identify and locate the bottlenecks, in the system under a number of different scenarios suggested by the client. There is also the flexibility to include additional duties that might be imposed on the Office.
Integrating new information and communication technologies in a group decision support system
Authors: Karacapilidis N.
Published: August 2006

We view group decision making as a collaborative process, where decision makers can establish a common belief on the dimensions of the problem by following a series of well‐defined communicative actions. Having first defined these actions, this paper reports on the exploitation of recent advances in information and communication technology, which can be used to: (i) remove the communication impediments among spatially dispersed decision makers; (ii) efficiently elicit and represent the domain of knowledge; (iii) develop efficient mechanisms to structure and consistently maintain the decision analysis; and (iv) automate the decision making process itself. Automation concerns coherence and consistency checking, detection of contradictions, truth maintenance, and information retrieval techniques.
A decision support system for automotive product planning and competitive market analysis
Authors: Guo W. , Weib K.C. , Lia X. , Wanga F.
Published: August 2006

A decision support system (DSS) for automotive product marketing, design and manufacturing in China is presented in this paper. The DSS is developed as a tool to support product planning, competitive market analysis, supply chain analysis and subsequent manufacturing systems planning and deployment. The system consists of a number of automotive related databases which provide information about manufacturers' performance in each market segment as well as production information of all existing market players in the Chinese auto industry. Product planning, one of the key modules of the DSS prototype, is highlighted in this paper. It supports decision makers in determining suitable strategies for market entry by analyzing existing competitors' status, growth estimation of each market segment, and competitive market analysis for new vehicle products. A case study for new market entry is included here to demonstrate the feasibility and effectiveness of the proposed methodology.
Linear programming applied to the flower sector: a Gladiolus bulb production case study
Authors: Caixeta‐Filho J.V. , van Swaay‐Neto J.M. , Lopes R.L.
Published: August 2006

Mathematical modeling structure was developed to support representative Brazilian bulb growing and trading company's decision making process, during the Gladiolus production planning activity. The pertinent LP model was focused on client's bulb requests to be attended and showed interesting results (e.g., profit maximization and suggestions for optimal combinations of types of bulblet and spacing to be planted).
Building scenarios for the University
Authors: Enserink B.
Published: August 2006

Scenario building is a tool for anticipating discontinuous change. Management staff at Delft University of Technology developed scenarios for the strategic environment of their future scientific staffing. A short intensive workshop with stakeholders was organized for developing the scenario‐logic. The same methodological approach was used by an interfaculty research group for determining its future research priorities. Although quite different in scope and methods used for idea generation and structuring, both groups succeeded in designing plausible, creative and consistent scenarios. The paper describes the methodology and the respective processes of scenario construction and shows that short, intensive, highly interactive workshops are a tool for creating a social basis for policy‐in‐the‐making.
The learning curve: a new perspective
Authors: Zangwill W.I. , Kantor P.B.
Published: August 2006

Despite the popularity of the “learning” curve, it should be called the “forecasting” curve. Given an industrial process, the traditional learning curve forecasts how costs are expected to decline (or other performance measures improve) in the future. Forecasting is certainly very useful. Nevertheless, the previous literature is notably mute on how the improvement or learning occurs. Without that information about how the process operates, the traditional learning curve cannot improve the rate of learning. This paper transforms the curve so that it not merely forecasts but rather actively creates the learning and knowledge. By extending work of the authors (Zangwill and Kantor, 1998), this paper constructs a new theoretical framework for learning and making improvements based upon learning cycles. This approach allows what is learned in one period to be intelligently applied to the next, improving the rate of learning right as production is occurring. Previous approaches could not do this. Because it should quickly increase the rate of learning, this approach might have important industrial applications.
A new parallel breadth first tabu search technique for solving production planning problems
Authors: Bock S. , Rosenberg O.
Published: August 2006

This paper presents a new parallel breadth first oriented tabu search extension, which can be used to improve existing tabu search procedures for production planning problems. Especially it is shown that this distributed technique considerably improves existing efficient sequential procedures for a well‐known assembly line balancing problem. Since this technique does not require any communication besides exchanging the solutions reached at the end of the computation, it can be installed on nearly every distributed system.
Analysis of a multi‐server queue with two priority classes and (M, N)‐threshold service schedule I: non‐preemptive priority
Authors: Feng W. , Kowada M. , Adachi K.
Published: August 2006

In this paper, we propose an (M, N)‐threshold non‐preemptive priority service schedule for a queueing system consisting of two‐parallel queues and a multi‐server. The arrival process for each queue is Poisson, and the service times are exponentially distributed with different means. We derive the generating functions of the stationary joint queue‐length distribution, and then obtain the mean queue length and the mean waiting time for each queue.
The ‘West Bank of the Drina’: land allocation and ethnic engineering in Republika Srpska
Authors: Ó Tuathail Gearóid , Dahlman Carl
Published: August 2006

The Bosnian war was driven by fantasies of geopolitical and demographic engineering which led to ethnic cleansing and the separation of Bosnia's ethnic qua national communities from each other. The post‐war peace opened up the possibility of returns, most especially the politically sensitive cross‐boundary return of Bosniaks to their old homes in Republika Srpska and Serbs to the residences in Bosnian Federation. This article considers one response of Bosnian Serb nationalist forces to returns, namely the strategy of distributing land plots to displaced Serbs to preserve the demographic consequences of ethnic cleansing. This study draws upon semi‐structured fieldwork interviews with international and local officials in Republika Srpska to contextualize the policy within former Yugoslav norms, post‐war Bosnian Serb politics and international community governance in Bosnia‐Herzegovina.
Islam, ethnicity and South Asian religions in the London 2001 census
Authors: Peach Ceri
Published: August 2006

The paper examines the relative strengths of the cross‐cutting variables of religion and ethnicity. British Muslims are often referred to as if they were a single community. The 2001 Censuses of England and Wales and Scotland demonstrate that Muslims are ethnically heterogeneous. Ethno‐religious ward‐level data for London from the 2001 census are used to test whether Islam binds together peoples of different ethnicity or whether ethnicity links groups despite religious differences. London Muslims, as a whole, are much less segregated than Sikhs, Jews or Hindus. Paradoxically this low level of overall segregation is produced by high intra‐Muslim ethnic segregation. Intra South‐Asian mixing irrespective of religion is greater than intra‐Muslim mixing, irrespective of ethnicity. Intra‐Black mixing is high irrespective of religion, while religion over‐rides race and ethnicity for Christian groups.
Infant and Neonatal Mortality for Primary Cesarean and Vaginal Births to Women with “No Indicated Risk,” United States, 1998–2001 Birth Cohorts
Authors: MacDorman Marian F. , Declercq Eugene , Menacker Fay , Malloy Michael H.
Published: August 2006

ABSTRACT:  Background:
The percentage of United States’ births delivered by cesarean section has increased rapidly in recent years, even for women considered to be at low risk for a cesarean section. The purpose of this paper is to examine infant and neonatal mortality risks associated with primary cesarean section compared with vaginal delivery for singleton full‐term (37–41 weeks’ gestation) women with no indicated medical risks or complications.
Methods:
National linked birth and infant death data for the 1998–2001 birth cohorts (5,762,037 live births and 11,897 infant deaths) were analyzed to assess the risk of infant and neonatal mortality for women with no indicated risk by method of delivery and cause of death. Multivariable logistic regression was used to model neonatal survival probabilities as a function of delivery method, and sociodemographic and medical risk factors.
Results:
Neonatal mortality rates were higher among infants delivered by cesarean section (1.77 per 1,000 live births) than for those delivered vaginally (0.62). The magnitude of this difference was reduced only moderately on statistical adjustment for demographic and medical factors, and when deaths due to congenital malformations and events with Apgar scores less than 4 were excluded. The cesarean/vaginal mortality differential was widespread, and not confined to a few causes of death.
Conclusions:
Understanding the causes of these differentials is important, given the rapid growth in the number of primary cesareans without a reported medical indication. (BIRTH 33:3 September 2006)
Surveillance of Cesarean Section Deliveries, New Jersey, 1999–2004
Authors: Denk Charles E. , Kruse Lakota K. , Jain Neetu J.
Published: August 2006

Abstract:  Background:
Nationally and in New Jersey, the cesarean delivery rate has been increasing steadily for nearly a decade, and especially since 1999. The purpose of this study was to describe recent trends in cesarean section delivery in New Jersey.
Methods:
Data on delivery method, medical indications and patient characteristics were extracted from electronic birth certificate files.
Results:
Cesarean section deliveries increased as a proportion of live births by 6 percent annually. Growth was roughly uniform across Robson’s clinical classification. Repeat cesareans contributed only proportionately to the overall trend. The greatest acceleration was observed for procedures without trial of labor, and in medical situations where cesarean delivery had been relatively rare.
Conclusions:
Medical indications recorded on the birth certificate explained little of the rapid growth in utilization of cesarean delivery, since trends were comparable in most categories we examined. A sustained autonomous shift in practice patterns, patient preferences, or both seems the most likely driver of the overall trend. (BIRTH 33:3 September 2006)