Hydropower at Canford: A Case Study in Investment Appraisal

This paper reports a case-study investigation into the economic desirability of generating hydroelectric power from the River Stour for Canford School, Dorset, as part of a larger feasibility study, which won a 1985 Molins Design Prize. A parametric discounting approach to net present-value assessment was used to examine the economic benefits of installing a small run-of-river hydropower scheme. Sensitivity analysis was used to clarify the effects of uncertainties in the limited cost and rate data available at the feasibility stage of the project. The role of the economic analysis in relation to other aspects of the feasibility study is indicated.     

The Design of Storage Calorifiers: A Case Study

To date, no scientific method for the sizing of storage calorifiers has existed. This short paper outlines the analytical methods which were established to provide design criteria for the storage calorifiers serving hospital ward units. A full report of the survey which was carried out is contained in a paper entitled “A study of water consumption in ward units”.     

The Adult Training Centre Problem: A Case Study

An optimal solution is found to a real-world problem which has the characteristics of a multiple travelling-salesman problem. It deals specifically with methods of obtaining the 'best' routeing for four vehicles which provide a daily service from a depot to 38 locations. The solution technique uses both heuristic and exact algorithms to derive the order for visits to the 38 locations.     

Records of Proceedings at Meetings

Held on Friday 15 November 1996 at the Linnean Society's Rooms,Burlington House, Professor N. J. Hitchin, FRS, President, inthe Chair. There were present about 110 members and visitors.     

Replacement-Policy Development: A Case Study of Glove Replacement at a Nuclear Processing Facility

Individual/group replacement models were used to identify the minimum-cost policy for replacing protective gloves that are utilized in product fabrication at a nuclear processing facility. Since historical data on glove longevity were not available to determine the failure-rate distribution, the classical replacement model for items that fail was modified to consider glove life as a normally distributed variable. Moreover, the absence of replacement-cost required that the classical model be transformed to incorporate the ratio of single to unit-group replacement cost. Sensitivity analysis on these two input parameter values provided guidance for the development of an appropriate replacement policy.     

Requisite Decision Modelling: A Case Study

This case study in decision analysis concerns a company that had to decide between continuing to manufacture an old product that might in the near future by banned by the government or introducing an improved but conventional product that would beat the ban but might lose market share to competing products using microchip technology. A decision tree with three attributes describing the consequences over a ten-year horizon modelled the problem. Implementation on a micro computer facilitated extensive sensitivity analyses, the final round of which were conducted by the Board of Directors. More and more pessimistic assumptions were made until the decision switched from the new to the old product; at that point no Director believed all the assumptions. Thus, agreement was reached about the decision even though the Directors disagreed about the uncertainties. The case illustrates ‘requisite’ rather than optimal decision modelling and shows the essential roles of problem structure and sensitivity analysis.     

Solid Waste Collection: A Case Study

Planning for urban solid waste management requires an assessment of many complex interactions among transportation systems, land use patterns, urban growth and development, and public health considerations. The authors discuss the application of a data acquisition and analysis system and a simulation model to the complex problems of the solid waste management system in Cleveland, Ohio. As the result of applying these techniques, Cleveland's solid waste managers reduced their annual budget of $14.8 million in 1970 to a low of $8.8 million in 1972. The total savings in a 3-yr period were $14.6 million based on the 1970 budget. In addition, the city reduced its solid waste work force from 1640 to 850 and the number of collection routes from 224 to 102, and it redesigned its collection routing system. The management structure of the Division of Solid Waste Collection and Disposal was completely reorganized to take advantage of and to supplement these major organizational changes. The City Council has, moreover, passed an ordinance which will allow the construction of transfer stations, as recommended in the study; one such facility has been built, and land has been purchased for the other.     

Optimization in Pottery Manufacturing: A Case Study

The paper reports what is believed to be the first application of mathematical programming to the manufacture of pottery. The problem has a number of distinctive features requiring special treatment in its specification. Short term (product mix) and medium term (acquisition of new plant) decisions within the firm are examined and a framework for the evaluation of improvements in methods to reduce production losses is given.     

Assessment of Manufacturing System Reliability: A Case Study

Reduction of unproductive work-in-process (WIP) inventory has been a subject of global concern lately. Detailed examination often reveals that such unproductive WIP is the result of a low manufacturing system reliability (MSR). The impact of poor MSR is felt all the more in industries where material cost constitutes a significant portion of the total manufacturing cost. Guided by these considerations, in this paper a case study is reported wherein an analysis has been made to assess MSR in a multinational switchgear industry located in Western India. The paper provides a few practical guidelines towards maintaining a certain level of MSR by suitably adjusting factors like utilization level of machines, utilization level of tools, tool down-time, mean production rate per tool, etc. Detailed sensitivity analysis on the simulation results has also been presented, which is believed to help substantially in decisions related to the finer adjustments of these factors.     

The Effectiveness of Substituting Locally Available Materials in Teaching Chemistry in Nigeria: A Case for Science Education in Developing Countries

This article investigates the effectiveness of improvising locally available materials for teaching chemistry in Nigeria, as a case for a culture of improvisation for teaching the sciences in developing countries. The scarcity and cost of imported materials for teaching science has remained a major challenge to teaching sciences in developing countries, and the fact that many teachers from developing countries tend to wait for these imported materials before they can teach continues to present a set‐back for science education in many non‐Western nations. In this experimental study, second year students in 3 Nigerian Senior Secondary schools in the state of Lagos, Nigeria, were sampled to determine whether there will be a significant difference in their performance when taught using imported materials compared to when taught using local substitutes. The study reveals that whereas their attitudes towards local materials may not be as positive as their attitudes towards imported materials, their performances did not differ when taught with either, as long as they were unaware of which material was local or imported. The result of this study proved that science education will flourish if teachers in Nigeria, and probably other developing countries, can begin to improvise local materials for science instruction.     

Optimal Size Selection in Standardization: A Case Study

Application of ‘preferred numbers’ to select the sizes of a product to be standardized may lead to relatively large ‘adaptation losses’ due to alterations and inefficient utilization. In this paper, a simple model is presented that can be used to select the sizes such that adaptation losses are minimal, given the number of sizes that is chosen. Application of this model reduces the adaptation losses usually by 20-40% and the production costs by 2-8%. The model is illustrated by a case study concerning the standardization of the horizontal dimensions of concrete piles.     

Chartwell Books: A Case Study in Mathematical Modelling

A case is described that has been used successfully many times as a vehicle for teaching mathematical modelling. The case has been closely derived from a consultancy assignment with Chartwell Books. The place of mathematical modelling within decision-support systems is examined, and this is followed by an outline of one such mathematical modelling methodology. The problem situation facing the managing director of Chartwell Books concerning the modelling of labour and material costs is described. A detailed application of the mathematical modelling methodology is worked through, finishing with a discussion of the value of the case for student teaching and of the problems that students have encountered when tackling the Chartwell case. Possible extensions to the basic methodology, such as validation and the human-computer interface, are also briefly considered.     

Multiple Container Packing: A Case Study of Pipe Packing

While the problem of packing single containers and pallets has been thoroughly investigated very little attention has been given to the efficient packing of multiple container loads. Normally in practice a multiple container load is packed by a single container algorithm used in a greedy fashion. This paper introduces the issues involved in multiple container loading. It lays out three different strategies for solving the problem: sequential packing using a single container heuristic, pre-allocating items to the containers and choosing container loads using simultaneous packing models. The principal simultaneous models are pattern selection IP models. We present an application of packing pipes in shipping containers using two pattern selection IP models, a pattern selection heuristic, a sequential greedy algorithm and a pre-allocation method. The experimental results use randomly generated data sets. We discuss several useful insights into the methods and show that for this application the pattern selection methods perform best.     

A Steel Pricing Case Study

Britain's entry into the European Community required fundamental changes to be made to the methods of charging U.K. home trade steel customers. The paper describes O.R. involvement in the design and implementation of the new charging methods for wide strip products sold by British Steel Corporation. The methodology employed was simple but none the less proved to be valuable in allowing management to make sense of what appeared at the outset to be a highly unstructured problem.     

The Impact of Automated Timetabling on Universities — A Case Study

Since September 1978, Memorial University of Newfoundland has registered its first-year students by a fully computerized timetabling and registration process. This system includes the provision of an individual class schedule for each student in a manner which optimizes the use of the University's classroom and timetable resources. This paper describes the reasons for the design of the computerized system, the characteristics of the system which was created, how the system currently works and its impact on the University. In particular, it illustrates how, given the appropriate administrative structure, the system can be used to help control (or even decrease) expenditures, at a time when increases in enrolment have outpaced those in budgets.     

Case Study: The Cost Minimization of Refuse Collection Operations

This paper describes an approach developed to minimize the cost of refuse collection operations in a city of 150,000 population. The method is general and applicable to a city of any size.A model is derived for collection which is a function of varied housing layouts, collection times, team sizes and the distance of the collection rounds from the disposal point. Then a computational method is developed which allocates collection operatives to vehicles and designs rounds which together minimize the total collection cost.The advantages of the method are:(a) It reduces collection costs. The “one-off” cost of applying the method to 10 per cent of the local authorities in the U.K. would be [pound]150,000 and yield a reduction in costs of [pound]500,000 p.a.(b) It enables management to replan rounds quickly as circumstances change.(c) Other applications, which are being investigated, are also discussed.     

Designing Modular Software: A Case Study in Introductory Statistics

Modular programming is a development paradigm that emphasizes self-contained, flexible, and independent pieces of functionality. This practice allows new features to be seamlessly added when desired, and unwanted features to be removed, thus simplifying the software's user interface. The recent rise of web-based software applications has presented new challenges for designing an extensible, modular software system. In this article, we outline a framework for designing such a system, with a focus on reproducibility of the results. We present as a case study a Shiny-based web application called intRo, that allows the user to perform basic data analyses and statistical routines. Finally, we highlight some challenges we encountered, and how to address them, when combining modular programming concepts with reactive programming as used by Shiny. Supplementary material for this article is available online.