Model-based assessment of military aircraft engine maintenance systems

The paper describes the development and use of a modular system dynamics model for analysing the dynamics and for assessing the long-term performance of military aircraft engine maintenance systems. Life-cycle engine maintenance is considered as a dynamic system whose behaviour is influenced by parameters specific to the engine's reliability and maintenance characteristics, to the operational requirements, and to the maintenance infrastructure. We show how the model can be used for supporting the aircraft procurement decision through the assessment of its engine's maintenance system, as well as for understanding and determining maintenance system behaviours, towards which operational adjustments of the maintenance infrastructure can be made in a more informed way.     

Models to estimate average route lengths in different geographical environments

This paper investigates how average route lengths for travelling salesman-type (TSP) journeys are influenced by the pattern and number of points visited. Two mathematical functions to estimate average route lengths are presented. The first function relates to average route lengths when n points are randomly located and the second to average route lengths when certain areas are more likely to be visited than the others, as defined by ‘demand surfaces’. Estimation of route lengths in this way can be a useful tool in the analysis of strategic and operational distribution problems, particularly in public services such as health and social services.     

Making decisions in the absence of clear facts

Bennis and O’Toole [Bennis, W.G., O’Toole, J., 2005. How business schools lost their way. Harvard Business Review 83, 96–104] have recently argued that decision makers need guidance in ‘making decisions in the absence of clear facts’. As such, decision makers must be able to resourcefully use whatever limited information is available and advantageously portray its implications. Based on recently published theory which directly addresses this requirement, this paper demonstrates, through a practical example, how decision makers can make systemic decisions in situations characterized by extremely limited information and, furthermore, what form such decisions can take. Evidence is provided, therefore, that operational research can effectively address what appears to be a gap in management training.     

Sources of Information for Operational Research Studies

The information explosion and the wide-ranging interests of operational research workers cause severe problems in the finding of information relevant to their studies. This paper attempts to show how an operational research worker can set about finding information for himself on any aspect of his work and a hundred examples of sources of information likely to be useful are briefly described with special reference to the needs of British workers.     

一种新的武器总体综合设计方法

对武器装备的作战效能、寿命周期费用、风险和研制周期的模型进行了研究,提出了综合运用这四维指标作为目标函数的武器总体综合设计的思路和数学模型,可以全面而系统地认识武器装备的发展问题,避免设计中由于只注重提高性能而引起的弊端.     

Adding value to bank branch performance evaluation using cognitive maps and MCDA: a case study

Bank branch performance evaluation is a difficult endeavour. Some of the main reasons for this difficulty are the complexity inherent in the variety of aspects considered in the evaluation, and the multiple and conflicting interests of the different stakeholders involved. In this paper, we show how cognitive mapping and measuring attractiveness by a categorical-based evaluation technique can be used to support the evaluation of bank branches through the development of multidimensional performance evaluation systems, and to deal explicitly with the trade-offs between the different dimensions of performance and interests of different stakeholders. A case study is discussed where these techniques are used in a constructive way, making the learning activity easier and introducing transparency in the decision-making process. The strengths and weaknesses of the integrated use of these two operational research techniques in this context are also discussed.     

Making efficient simulation experiments interactively with a desktop simulation package

It has been shown how a design of simulation experiments methodology can be used interactively with practical simulation models constructed in a desktop simulation package (SIMUL8). The methodology includes new ideas on how to improve the accuracy of a simulation response. It is implemented as a set of computer program modules that are not specific to a particular simulation model and provide an interface that lets the modeller construct an efficient simulation experiment with only an operational understanding of how the methodology works. The methodology and program modules are illustrated with a practical simulation model, and the results show how they can improve simulation response with negligible increase in computational effort.     

Operational Research Education for Practitioners and Managers∗

The paper reviews the history of education in operational research and indicates the needs both of a practitioner and of a manager. It describes how these can be met by standard course teaching and suggests some areas of development.

     

Constraint satisfaction problems: Algorithms and applications

A constraint satisfaction problem (CSP) requires a value, selected from a given finite domain, to be assigned to each variable in the problem, so that all constraints relating the variables are satisfied. Many combinatorial problems in operational research, such as scheduling and timetabling, can be formulated as CSPs. Researchers in artificial intelligence (AI) usually adopt a constraint satisfaction approach as their preferred method when tackling such problems. However, constraint satisfaction approaches are not widely known amongst operational researchers. The aim of this paper is to introduce constraint satisfaction to the operational researcher. We start by defining CSPs, and describing the basic techniques for solving them. We then show how various combinatorial optimization problems are solved using a constraint satisfaction approach. Based on computational experience in the literature, constraint satisfaction approaches are compared with well-known operational research (OR) techniques such as integer programming, branch and bound, and simulated annealing.     

An education in operational research: A personal viewpoint

A distinction is drawn between management, management science and operational research, which determines the content of operational research courses. Personal views are expressed on how the subjects should be taught and practical experience given, so fitting graduates for careers in operational research and in management.     

Operational Research and Corporate Planning in Railway Management

The current corporate planning process in Westrail is described and the roles played by operational research and mathematical modelling identified. They do not include forecasting the future. Instead of the "predict and prepare paradigm" a planning approach that tries to design the future has been adopted. The organisation is described in terms of how it has evolved, what it now is, and the key features of its environment. The three stages of planning are described-strategic, tactical and operational. These provide the means for management control of the railway. Environmental assessments linked to goal setting activities are incorporated within the planning process. The significance of operational research in planning, in particular mathematical modelling, is also described. Instead of finding problems to which existing techniques can be applied, O.R. is used to provide effective operational and planning systems as a means of assisting management to design the future for the organisation.     

Object-Oriented Modelling of Military Communications Networks

Military communications networks are large complex systems; their physical dynamics, composition, workload characteristics and operational goals make them very hard to model and analyse. It is particularly difficult to build a generalized model that can adequately fit each instance, generate a workload that exercises the network in a realistic way, and measure network effectiveness in terms of the operational goals. In this work, we describe our approach to building such a model for the US Marine Corps, and demonstrate the model's use by solving a particular equipment allocation problem. We combine object-oriented simulation with new concepts for workload modelling and measuring effectiveness that are based on the operational tasks the Marines perform.     

Operational Research in the Central Electricity Generating Board

The growth and developments in the organization of the Electricity Supply Industry are outlined and the way in which operational research has been fitted into the organization as a number of separate, co-operating teams is described.Some of the main problems of the Generating Board are explained and the contributions that have been made and that might be made by operational research are discussed.A picture is presented of the widening appreciation of the utility of operational research which, beginning as a service used almost wholly on operational problems of generation, is now being used by an increasing number of departments.     

The optimal operational risk capital requirement by applying the advanced measurement approach

The purpose of this paper is to construct a risk quantification model to achieve the accurate operational risk management and gain the satisfying estimation and control of future possible extreme losses by using capital charges to assess operational risk. The paper takes a case bank as the research object and compares the differences under various circumstances engaging the Basic Indicator Approach, the Standardized Approach, and the Advanced Measurement Approach for the operational risk capital requirement of a bank. The results indicate that it is more appropriate to adopt the Advanced Measurement Approach to estimate the operational risk capital requirement; this way can help a bank enjoy a much lessened capital charge required and subsequently its available capital increases. Hence, it allows a bank to have sufficient funds in operations and reduce the burden of capital costs. Therefore, it will bring the positive benefits to the whole banking industry when enforcing the Advanced Measurement Approach.     

Synthetic Impedance Circuits in Semi-Passive Vibration Control with Piezo-Ceramics - Efficiency and Limitations

Electrical circuits that represent complex impedance connected to the plates of piezo element affect the frequency response function of compound electromechanical systems. The external network consisting of inductance results in absorbing a certain frequency of vibrations. The performance can significantly be increased using negative capacitance. All the negative impedance elements are achievable via semi-passive way with the use of an electronic gyrator realized by operational amplifiers that require power supply. Its performance is limited due to the maximum voltage operational amplifiers can produce. The higher excitation forces require higher output voltages of amplifiers. The aim of the paper is to present the relation between the required voltage on synthetic impedance and force excitation in 1DOF vibrating system regarding parameters of piezo element and mechanical system for absorbing case. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Teaching Operational Research Technique

Good technique, i.e. competence in carrying out operational research, is as vital for the practitioner to acquire as competence in the traditional ‘techniques’. It is suggested that universities should teach students how to conduct simple projects prior to alerting them to more sophisticated methodological issues.As an aid to this task, the traditional five or six parts of an operational research project are broken down and extended into 39 steps, and regrouped into three phases. Also, five skills are identified as being conceptually essential to "good" operational research, which students can develop through tackling suitable case studies.     

The Implications of Cognitive-style Findings for Operational Research

Cognitive style refers to differences that can be perceived in individuals due to differing cognitive structures. There has been a large amount of research on how cognitive style affects managerial decision-making, particularly in the context of management information systems, but little or no attempt to relate these findings to operational research. This paper reviews the findings of cognitive-style research from the perspective of operational research, and draws a number of useful inferences concerning the matching of OR aids to managers, the presentation of information and recommendations, the use and acceptance of OR, and the structure of OR groups. Further, it is argued that cognitive-style findings help to give a justification to the move towards ‘soft’ approaches to analysis.     

Profile of Current Members of the Operational Research Society

The study described here was based on a questionnaire survey in the summer of 1967 of all the then members of the Operational Research Society. It concerns factual data about Operational Research Society members relating to their general background, the area of operational research and the industry they are engaged in, age and salary, undergraduate and postgraduate education, training in operational research, time spent in operational research and in industry prior to operational research. It examines the relationships between these aspects of their background and looks for trends which may indicate how the nature of the men entering the profession may be changing.