The initiation,evaluation and selection of operational research projects

This paper discusses the problems involved in conducting successful Operational Research within a large organisation and suggests ways of overcoming them. It describes ways in which Operational Research projects arise, methods of assessing their relative merits, and methods used by the authors to obtain a suitable portfolio of projects. It is argued that an Operational Research Group should apply to its own project planning the scientific approach that it advocates for others.     

Facilitating problem definition in teams

The problems that a team comes to define as needing to be worked on depend upon idiosyncratically defined subjective, qualitative and organizationally political factors affecting the individual members of the team. In this paper we shall argue that Operational Research tends to pay little attention to the process of problem definition and that when it does, the emphasis is towards determining an accurate or correct interpretation of the external situation that the team confronts and the organizational objectives which have been laid down for the team. We suggest, however, that Operational Researchers are particularly well placed to act in a way which pays attention to both these fields. This paper is addressed to those Operational Researchers who predominantly work with complex policy problems belonging to a team of decision-makers. We shall demonstrate that group techniques, new computer simulation technology, and attention to process can lead to a team negotiating a definition and redefinition of a problem so that solutions have a greater commitment from the team, and therefore a higher chance of being implemented.     

基于概念的数学系统及其结构

随着科学技术的发展，应用定量分析的数学方法已从自然科学发展到社会科学、思堆科学．为了处理这些问题的需要，许多学者建立了多种数学模型和数学方法，这些模型和方法都直接或间接地涉及到概念，因此归纳并研究基于概念的数学方法显得很有必要。本文应用系统的方法，尝试络出数学系境的概念，并建立了基于概念的数学系统及其结构的一般方法，期望更多的学者予以关注和研究。     

运筹学在复杂网络社团结构分析中的应用

社团结构研究是复杂网络这一前沿领域中的重要问题,同运筹学有着密切的关联。本文介绍了传统社团结构问题的基本定义,以及最近十年通过应用运筹学理论对该问题的研究进展。这些进展包括启发式模型,到随后的概率优化模型,以及组合优化模型。通过这些介绍,说明了运筹学方法论和基本工具在复杂系统研究中所起到的重要作用。     

Forty Years On: Challenges and Successes

The 40th anniversary of the Operational Research Society has prompted an informal survey of the successes of Operational Research over that period and the challenges still to be met. This triggers comments on the areas where the subject still needs development, including more concentration on publicizing the operational science aspects of the subject. Finally, the way the Society is shaping up to some of these challenges is discussed.     

A note on “Location of hubs in a competitive environment”

This note suggests modifications to two models for locating hubs in a competitive environment introduced by Marianov et al. [European Journal of Operational Research 114 (1999) 363–371]. They make it possible to provide optimal solutions much faster. It is also shown that the implementation of the heuristic proposed by Marianov et al. contains a flaw. Yet the heuristic itself is correct.     

In Praise of Unicorns

The general thrust of this paper will be to put the recent ‘King is Dead’ controversy into its proper perspective, to review the consequences of Russell Ackoff's criticisms of the 1978 Conference, to look with a critical yet benevolent eye on university courses in the light of these criticisms and to suggest a menu of unsolved problems which might indicate exciting developments in our subject.The paper will start with a discussion of the three disasters which have hit Operational Research in the last twenty years. It is the contention of the speaker that the ‘King is Dead’ controversy was largely a controversy about nothing of significance and, by sapping the energies of those who could otherwise have been constructively employed, was itself one of these disasters (the other two can be left as exercises for the reader).The criticisms of Russell Ackoff were of a much more substantial nature. The author does not agree completely either with Ackoff's diagnosis or his suggestion of the way the patient should be treated. The paper will suggest ways in which the universities have reacted to these criticisms and the extent to which they are moving away from the mind-bending dullness and boredom which seems to run through so much Operational Research teaching. The place of universities in contemporary society will be discussed with particular emphasis on research and on the need to serve the community.We shall discuss an outline of some of the major unsolved problems which at present are largely ignored by Operational Research scientists. None of these problems involves or needs the development of formal mathematics and for that reason they are much more difficult than the normal problems on which mathematicians give their advice. The paper will try to convey the sense of intellectual excitement which is needed to be reintroduced into Operational Research, particularly in order to move away from the nervous, defensive and apologetic posture assumed by so many Operational Research scientists as a reaction to recent criticisms.     

Adaptive Filtering: An Integrated Autoregressive/Moving Average Filter for Time Series Forecasting

Journal of the Operational Research Society - This paper extends the applicability of a heuristic filtering technique, adaptive filtering, by dealing with a number of practical considerations in...     

Assessing problem complexity

The difficulty of objectively measuring the decision-making load imposed by a complex decision problem on a human decision maker is identified. It is suggested that a technique for such measurement would be useful in Operational Research. The secondary task technique, a method much used by psychologists and ergonomists to assess the mental processing load presented to subjects by a variety of tasks, is discussed. It is observed that the type of complex problem often of interest in Operational Research is characterised by the involvement of model building in the process of solution. An experiment is presented to compare the mental load presented by a number of different chess problems using a mental arithmetic secondary task, and it is shown that the method appears to be valid for the study of complex problems.     

A note on the proportionate flow shop with a bottleneck machine

Choi, B.-C., Yoon, S.-H., Chung, S.-J., 2007. Minimizing maximum completion time in a proportionate flow shop with one machine of different speed. European Journal of Operational Research 176, 964–974 consider the proportionate flow shop with a slow bottleneck machine and propose the SLDR heuristic for it. Choi et al. (2007) derive a data-dependent worst-case ratio bound for the SLDR heuristic which is then bounded by two. In this note, we show that the tight worst-case ratio bound of the SLDR heuristic is 3/2.     

Corporate Planning and Its Use of O.R. in the N.C.B.: A Personal View

Moving from Operational Research to Corporate Planning within one organisation is a rather modest change, which nevertheless leads to a different perspective. While still an advisory function, Corporate Planning, to be successful, has to maintain itself at the centre of a `messy' system tackling `messy' problems. Holding on to a clear strategy in such circumstances is not only difficult but vital. The success of the strategy depends on its robustness and ability to adapt to new circumstances. Recent debates in the O.R. literature have focused on the importance of robustness and the nature of uncertainty using the paradigms of rational and bureaucratic processes. This is a useful perspective from which to view our activities and the relative roles of Operational Research and Corporate Planning, either separately or together. The term `mature' O.R. is used to differentiate research that has been built up over many years in the N.C.B. from the problem solving activity often used to characterise O.R. The challenge is to prevent maturity developing into old age.     

A study of heuristic combinations for hyper-heuristic systems for the uncapacitated examination timetabling problem

Research in the domain of examination timetabling is moving towards developing methods that generalise well over a range of problems. This is achieved by implementing hyper-heuristic systems to find the best heuristic or heuristic combination to allocate examinations when constructing a timetable for a problem. Heuristic combinations usually take the form of a list of low-level heuristics that are applied sequentially. This study proposes an alternative representation for heuristic combinations, namely, a hierarchical combination of heuristics. Furthermore, the heuristics in each combination are applied simultaneously rather than sequentially. The study also introduces a new low-level heuristic, namely, highest cost. A set of heuristic combinations of this format have been tested on the 13 Carter benchmarks. The quality of the examination timetables induced using these combinations are comparable to, and in some cases better than, those produced by hyper-heuristic systems combining and applying heuristic combinations sequentially.     

The Curse of Unintended Rounding Error: A Case from the Vehicle Scheduling Literature

In their recent paper, which was published in the Journal of the Operational Research Society, Cheshire et al. describe "A dual heuristic for vehicle scheduling". The authors claim, on the basis of 17 academic test problems from the vehicle scheduling literature, that "in most cases the new results are comparable with those of Foster and Ryan, whose technique showed improvements over all previous methods". But a careful examination of the relevant source materials shows that one subset of authors, which includes the authors mentioned here, forced possibly premature rounding upon intermediate results in their calculations. Thus the comparisons performed by Cheshire et al., and their conclusions, are suspect in principle. They are later shown to be rather misleading in practice.     

Critical heuristics of social systems design

Health care planning, city and regional planning, energy and transportation planning, environmental design and other areas of social systems design are becoming issues of increasing concern to policy makers. Faced with complex steering problems that may have far-reaching societal implications, they except help from applied disciplines such as Operational Research, systems science, technology assessment, program evaluation, cost-effectiveness analysis, and similar approaches to scientifically informed planning. But these approaches offer little help in critically reflecting on the normative implications of the problem definitions and solution proposals they inspire.Critical Heuristics seeks to provide both the involved planners and affected citizens with a conceptual framework for identifying and discussing the normative implications of problem definitions, systems designs, program evaluations, etc. The paper introduces some key concepts of Critical Heuristics and briefly discusses their significance to ‘rational’ planning.     

An exact algorithm for the fixed-charge multiple knapsack problem

We formulate the fixed-charge multiple knapsack problem (FCMKP) as an extension of the multiple knapsack problem (MKP). The Lagrangian relaxation problem is easily solved, and together with a greedy heuristic we obtain a pair of upper and lower bounds quickly. We make use of these bounds in the pegging test to reduce the problem size. We also present a branch-and-bound (B&B) algorithm to solve FCMKP to optimality. This algorithm exploits the Lagrangian upper bound as well as the pegging result for pruning, and at each terminal subproblem solve MKP exactly by invoking MULKNAP code developed by Pisinger [Pisinger, D., 1999. An exact algorithm for large multiple knapsack problems. European Journal of Operational Research 114, 528–541]. As a result, we are able to solve almost all test problems with up to 32,000 items and 50 knapsacks within a few seconds on an ordinary computing environment, although the algorithm remains some weakness for small instances with relatively many knapsacks.     

A Survey of Local Delivery Vehicle Routing Methodology

Vehicle routing techniques which have offered fascinating combinatorial problems to the academic operational research worker, become of real concern to practitioners of Operational Research as managements become increasingly aware of the need to control the rising costs of the physical distribution activity. The systematic construction of efficient vehicle route structures for local delivery operations provides an important tool for the control of costs in the short-term, for adapting the vehicle fleet size and composition in the medium-term, and even for the location of depots in the longer term.The bases of the many heuristic algorithms which have been proposed in the literature for the design of efficient vehicle route structures are critically appraised. The issues which arise when integrating such techniques into an operational setting are described in the light of the real needs of management. It is concluded that the design of "flexible fixed routes" is the real target which only a few of the many algorithms can approach.     

A particle swarm optimization algorithm for makespan and total flowtime minimization in the permutation flowshop sequencing problem

In this paper, a particle swarm optimization algorithm (PSO) is presented to solve the permutation flowshop sequencing problem (PFSP) with the objectives of minimizing makespan and the total flowtime of jobs. For this purpose, a heuristic rule called the smallest position value (SPV) borrowed from the random key representation of Bean [J.C. Bean, Genetic algorithm and random keys for sequencing and optimization, ORSA Journal of Computing 6(2) (1994) 154–160] was developed to enable the continuous particle swarm optimization algorithm to be applied to all classes of sequencing problems. In addition, a very efficient local search, called variable neighborhood search (VNS), was embedded in the PSO algorithm to solve the well known benchmark suites in the literature. The PSO algorithm was applied to both the 90 benchmark instances provided by Taillard [E. Taillard, Benchmarks for basic scheduling problems, European Journal of Operational Research, 64 (1993) 278–285], and the 14,000 random, narrow random and structured benchmark instances provided by Watson et al. [J.P. Watson, L. Barbulescu, L.D. Whitley, A.E. Howe, Contrasting structured and random permutation flowshop scheduling problems: Search space topology and algorithm performance, ORSA Journal of Computing 14(2) (2002) 98–123]. For makespan criterion, the solution quality was evaluated according to the best known solutions provided either by Taillard, or Watson et al. The total flowtime criterion was evaluated with the best known solutions provided by Liu and Reeves [J. Liu, C.R. Reeves, Constructive and composite heuristic solutions to the P∥∑C_i scheduling problem, European Journal of Operational Research 132 (2001) 439–452], and Rajendran and Ziegler [C. Rajendran, H. Ziegler, Ant-colony algorithms for permutation flowshop scheduling to minimize makespan/total flowtime of jobs, European Journal of Operational Research, 155(2) (2004) 426–438]. For the total flowtime criterion, 57 out of the 90 best known solutions reported by Liu and Reeves, and Rajendran and Ziegler were improved whereas for the makespan criterion, 195 out of the 800 best known solutions for the random and narrow random problems reported by Watson et al. were improved by the VNS version of the PSO algorithm.     

Bridging the gap between clinicians and health managers

This contribution is about bridging the gap between professionals and managers in health care: clinicians on the one hand and managers on the other hand. The paper looks at the problems along the road ahead: those that confront the governmental authorities and those that confront the health care sector. It identifies the driving forces that confront the health care sector and shows in what direction they are pushing management. Three steps are indicated to bridge the gap between clinicians and managers: (1) New discussion forums; (2) patient information systems; (3) communication tools. Operational Research can and should contribute. However, some shifts in emphasis are necessary. Three propositions are put forward: (1). Operational Research should infiltrate the discussion forums on health care; (2) Operational Research should orient itself to the “operationalisation” of the thousands of basic concepts and indicators used in health care rather than to the formulation of models which take all these concepts and indicators for granted; (3) Operational Research can contribute by helping to master the voluminous data in sensible ways in order to arrive at information on health, health care and health care management… under any type of constraint, resource or otherwise. This information needs, however, to be communicated.     

The Language of Operational Research

This paper is concerned with the language used to describe the OR approach. Much confusion is caused by a failure to properly distinguish Operational Research from science. Recognising the distinctions that should exist, leads to a modification of the model of the practice of OR and could lead to more practical papers being published in the journals.