Replenishment at Sea

This paper describes a case study on the logistics of replenishing a naval warship group. A discrete simulation model of the system was developed. A rule-based adviser was then embedded into the model, thus providing an intelligent decision-maker to automate the simulation model. The simulation methodology was later transformed from simple event-scheduling to the three-phase eLSE system, in preparation for future integration work. Some observations are made about the simulation methodologies used.     

Gas Supply and Storage Planning: A Simulation Approach

This paper describes the problems faced by a region of British Gas in forecasting daily gas demand and gas storage requirements. The discrete simulation approach is used to model the gas supply system. The paper discusses how the relationships and interactions between the various parts of the system may be determined by using the simulation program which has been developed and implemented.     

Using Simulation in Capacity Planning

This paper describes a case study concerning the application of simulation to manufacturing capacity planning. Visual interactive models were developed and used to investigate the manufacturing strategy for a particular organization. However, there are several practical difficulties which may arise in using these techniques to support managerial decisions. One of these concerns the meaning of the term ‘manufacturing capacity’. This problem was overcome by using a visual interactive version of an established procedure to complement the use of a simulation model.     

A Simulation Model for Calculating Annual Congestion Delay Arising from Airport Runway Operations

This paper describes a simulation model of delays to aircraft caused by airport runway congestion. It was developed for the Australian Government as part of the Sydney Airport Project. Subsequently, it was used in a traffic management study of the airport which examined the scope of deferring the need for additional runway capacity by adopting administrative measures affecting runway utilization.     

A Computer Simulation Model Applied to Design Problems of a Petrochemical Complex

This paper describes a computer simulation model which was developed by BP Chemicals International and applied to some of the design problems of a petrochemical complex. The individual plants in this type of complex are closely interlinked in terms of input and output of raw materials, usage from common storage tanks and utilities requirements. Thus decisions taken within a particular area can have serious effects on overall site performance. The simulation model was constructed to assist management in evaluating the consequences of alternative design decisions.The structure and data requirements of the model are described and special mention is made of the decision rules used to arrive at a feasible mass balance. Limitations of the model are discussed and some sample applications are presented, including the problem of the sizing of storage tanks.     

Combining simulation and goal programming for healthcare planning in a medical assessment unit

This paper describes a detailed simulation model for healthcare planning in a medical assessment unit (MAU) of a general hospital belonging to the national health service (NHS), UK. The MAU is established to improve the quality of care given to acute medical patients on admission, and to provide the organisational means of rapid assessment and investigation in order to avoid unnecessary admissions. The simulation model enables different scenarios to be tested to eliminate bottlenecks in order to achieve optimal clinical workflow. The link between goal programming (GP) and simulation for efficient resource planning is explored. A GP model is developed for trade-off analysis of the results obtained from the simulation. The implications of MAU management preferences to various objectives are presented.     

An Operations Research Approach to the Problem of the Sugarcane Selection

Selection for superior clones is the most important aspect of sugar cane improvement programs, and is a long and expensive process. While studies have investigated different components of selection independently, there has not been a whole system approach to improve the process. This study observes the problem as an integrated system, where if one parameter changes the state of the whole system changes. A computer based stochastic simulation model that accurately represents the selection was developed. This paper describes the simulation model, showing its accuracy as well as how a combination of dynamic programming and branch and bound can be applied to the model to optimise the selection system, giving a new application of these techniques. The model can be directly applied to any region targeted by sugarcane breeding programs or to other clonally propagated crops.     

The Use of Models for Environmental Forecasting and Corporate Planning

This paper presents briefly, the forecasting and planning activities which have evolved over the years in Esso Petroleum Company. It describes three computer models developed in the Corporate Planning Department for these activities an econometric model for short-term environmental forecasting and economic analysis; a horizon year optimization model for long-range corporate objectives setting; and a multi-time period simulation model for financial forecasting and planning both in short and long term. The structure, use and limitations of each of the models are discussed.     

Linking Discrete-Event Simulation Models with Expert Systems

This paper describes experiments designed to test the feasibility of linking discrete-event simulation models with expert systems. Two microcomputer systems are used: one contains the simulation model, while the other contains the expert system. The paper shows that by linking a simulation model with an expert system, it is possible to use the combination for simulation parameter learning, expert system development and expert system control of a simulation model.     

A generic model for simulating office process flows

In the field of simulation, the use of application-specific software can bring many benefits to the model-builder in terms of improved productivity and reduced skill requirements. Such software must have at its core a robust generic model for the application area which offers both the generality and sufficient detail to be able to simulate realistically. To develop such a core model, a thorough understanding of the problem area and simulation is needed. This paper describes one design for a generic core model for the simulation of office process flows where work volumes are substantial. It forms a part of a software package called SCOPE which provides a user-interface for data capture, and generates simulation models to be run using the HOCUS simulation software. Also described is the facility for static modelling which has been developed to make further use of the captured data using conventional mathematical modelling.     

Besmod: A strategic balance sheet simulation model

Besmod is a strategic balance sheet simulation model, developed and used for the strategic planning process in the First Austrian Bank. The paper describes the basic concept, the modular structure and the technical realisation of the model. After explaining how to handle the input specifications the experiences using Besmod are reported.     

A simulation-based study of a NHS Walk-in Centre

This paper describes a simulation-based project to help North Mersey Community National Health Service Trust to design and plan the operation of a NHS Walk-in Centre. The simulation model developed of this multi-service facility was used to facilitate managers and health professionals to recognize existing problems and potential future problems, and to investigate ideas for their ‘solution’. In the fast-moving NHS where initiatives to improve access, such as walk-in centres, are a recent development and where no two centres are the same, ideas for best practice borrowed from elsewhere can be quickly tested for suitability in the local situation.     

The Use of Closed Queues in the Deployment of Coal-Face Machinery

Expensive coal-face machinery is deployed to collieries from centralized pools. This paper describes a study of the deployment cycle of such equipment to determine what scope for improvement existed. A queueing model was used to establish the main factors affecting the system and this model enabled broad operating principles to be established. Further analysis was done using a simulation model, the salient features of which are described. The paper goes on to describe how the simulation model was used to lead to the conclusion that the complexity of the deployment cycle could be reduced to the consideration of two simple parameters.     

Hospital bed requirements planning

Within the current environment of British government public spending cuts, the effective use of National Health Service resources is now probably more important than at any time since its formation. For this reason the Management Science Department of University of Swanswa have developed a simulation model to aid decision making in the area of operating theatre time tables and the resultant hospital bed requirements. It has already have agree that the model be adopted in one large South Wales hospital. This paper describes the formulation of the model, the results obtained and its applications within the hospital service.     

A finite volume simulation model for saturated–unsaturated flow and application to Gooburrum,Bundaberg, Queensland,Australia

In this paper, a two-dimensional control volume finite-element computational model is developed for simulating saltwater intrusion in a heterogeneous coastal alluvial aquifer system at Gooburrum located near Bundaberg in Queensland, Australia. The model consists of a coupled system of two non-linear partial differential equations. The first equation describes the flow of a variable-density fluid, and the second equation describes the transport of dissolved salt via a form of the Fokker–Planck equation. The outcomes of the work demonstrate that transport simulation techniques provide excellent tools for hydraulic investigations even when complex transition zones are involved.     

Modeling Reputation Management System on Online C2C Market

This paper discusses the effectiveness of sharing information concerning the reputations of buyers and sellers making online transactions in a consumer-to-consumer (C2C) market. We developed a computer simulation model that describes online transactions with a reputation management system that shares information concerning the reputations of consumers. The model takes an agent-based approach in which agents' actions are based on the iterated prisoner's dilemma. No model exists to analyze C2C markets even though there are many case studies concerning the effectiveness of sharing reputation information among participants in a market. The simulation results revealed that a positive reputation system can be more effective than a negative reputation system for an online transaction, even though the negative one can work for a traditional transaction. The result should be an important consideration when designing practical reputation management systems for online transactions.     

Prison Perimeter Cost-Effectiveness

This paper describes a study which was carried out for Home Office Prison Department. The problem under review was that of providing cost-effective Perimeter Security for Prisons. This involved identifying performance measures for prison perimeters. First performance and cost measures had to be found for individual elements of a perimeter (for example, walls, cameras). Next, a mathematical formulation was developed to assess the cost-effectiveness of perimeter cross-sections as a whole. The mathematical model has formed the basis of a computer model. This paper describes the development and use of the computer model and outlines areas of development for the future.     

An Equipment Replacement Problem

This paper describes a study undertaken to develop a model for the replacement of a particular type of machine. The dominant operating costs are identified, and existing replacement models reviewed. One of the most important factors is the cost of production stoppages which can sometimes result from the breakdown of these machines. In order to predict the effects of this in terms of the machines' age, a simulation model is developed.The results from the replacement model are investigated in terms of their sensitivity to the variability in the estimates of the parameters required by the model. In particular some interesting results relating the method used for calculating the resale values and the optimal replacement interval are presented.     

Simulation for business process re-engineering: case study of a database management system

This paper describes the use of discrete event simulation in the resource, throughput and content analysis and improvement of a business process in the Iranian Information and Documentation Centre (IRANDOC). The process was initially mapped using Data Flow Diagrams (DFD), and the objectives of the study for a range of users were captured using the Delphi method. The time taken for the tasks in the process were estimated by work study, and the simulation was developed in ServiceModel?. The simulation was valuable in understanding why the current systems were not performing satisfactorily and led to a number of proposals for improvement. This mixed use of hard (simulation) and soft (Delphi) methods proved a fruitful way to gain process improvements and could be employed in other organisations.     

A sequential method for the development of visual interactive meta-simulation models using neural networks

This paper proposes a practical and efficient method for the development of visual interactive meta-simulation models using neural networks. The method first uses a randomised simulation experimental design to obtain a set of results from a previously validated simulation model. The bootstrap technique is used on these results to generate a series of neural network models that are then trained using back propagation. The visual interactive meta-simulation model consists of the collective response from the trained neural network models. The accuracy of the meta-simulation model is assessed using the bootstrap technique and improved accuracy obtained by increasing the size of the randomised simulation experimental design set and re-training. This paper describes the approach, gives results for five example problems and suggests that the method is a practical extension to visual interactive simulation.