Browsing by Author "Saw, R."

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    An alternative approach to inventory control and forecasting methods in the public and private sectors
    (1989-10) Southworth, M. S.; Saw, R.
    This research was spawned by the questions and answers from the 33rd report of the committee of Public Accounts session 1983-84. The Key to the ensuing arguments about the report hinged on 3 words "Best Commercial Practice". In order to deduce a baseline the present systems of public and private concerns were investigated to find out what is actually being done. The thesis research examined what is actually happening today and in certain instances where companies have been prepared to speculate (and be open) what they believe they will be doing in the future. A review of the American and Germany Army systems has been included to ensure that the question 'best practice' could be examined between other systems having identical constraints^ The research includes both new and old literature by both academics and practitioners of the science of inventory. The hypothesis is that inventory is regarded in the singular whereas for all large concerns it should be considered in the plural, how the plural should be defined, what and how these sub inventories are and how they should be identified. The hypothesis whilst proven has the caveat that it only relates to inventories which are subject to similar structures and constraints. The effect of implementing the hypothesis in a working environment, possible areas for future work and research, largely due to the embryonic technical breakthroughs in information technology are examined briefly. The recommendations and conclusions represent an alternative approach to inventory control and forecasting not previously covered by either theoretical or practical work.
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    A computer graphics approach to logistics strategy modelling
    (Cranfield University, 1990-11) Khan, Q.; Rushton, A. S.; Saw, R.
    This thesis describes the development and application of a decision support system for logistics strategy modelling. The decision support system that is developed enables the modelling of logistics systems at a strategic level for any country or area in the world. The model runs on IBM PC or compatible computers under DOS (disk operating system). The decision support system uses colour graphics to represent the different physical functions of a logistics system. The graphics of the system is machine independent. The model displays on the screen the map of the area or country which is being considered for logistic planning. The decision support system is hybrid in term of algorithm. It employs optimisation for allocation. The customers are allocated by building a network path from customer to the source points taking into consideration all the production and throughput constraints on factories, distribution depots and transshipment points. The system uses computer graphic visually interactive heuristics to find the best possible location for distribution depots and transshipment points. In a one depot system it gives the optimum solution but where more than one depot is involved, the optimum solution is not guaranteed. The developed model is a cost-driven model. It represents all the logistics system costs in their proper form. Its solution very much depends on the relationship between all the costs. The locations of depots and transshipment points depend on the relationship between inbound and outbound transportation costs. The model has been validated on real world problems, some of which are described here. The advantages of such a decision support system for the formulation of a problem are discussed. Also discussed is the contribution of such an approach at the validation and solution presentation stages.
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    Configuring Simulation Models Using CAD Techniques: A New Approach to Warehouse Design
    (Cranfield University, 1992-10) Brito, A. E. S. C.; Saw, R.
    The research reported in this thesis is related to the development and use of software tools for supporting warehouse design and management. Computer Aided Design and Simulation techniques are used to develop a software system that forms the basis of a Decision Support System for warehouse design. The current position of simulation software is reviewed. It is investigated how appropriate current simulation software is for warehouse modelling. Special attention is given to Visual Interactive Simulation, graphics, animation and user interfaces. The warehouse design process is described and common difficulties are highlighted. A Decision Support System (DSS) framework is proposed to give support during all the warehouse design phases. The use of simulation in warehouse design is identified as being essential for evaluating different warehouse configurations. Several simulation models are used to show that the warehouse systems special characteristics require a new way of defining the simulation model and new modelling elements to represent the complex logic of a warehouse system. AWARD (Advanced WARehouse Design) is a data-driven generic model, developed to build warehouse simulation models. It uses Computer Aided Design (CAD) techniques for drawing the warehouse layout and configuring the simulation model. The user has no need for programming skills and a user-friendly interface makes it easy to use. High resolution colour graphics and a scale drawing of the warehouse makest he dynamic display of the model a good representationo f the real system. Several examples illustrate the use of the AWARD system. The experience and advantages of the AWARD approach is discussed and the extension of this approach to other areas is explored.
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    An integrated approach to logistics strategy planning using visual interactive modelling and decision support
    (Cranfield University, 1994-10) Guedes, A. P.; Saw, R.
    The research in this thesis relates to the use of mathematical models and ièigputer-based modelling tools for supporting the Logistics Strategy Planning (LSP) process. conceptual modelling framework and a computer-based modelling and decision support system are developed to address practical LSP problems and improve the level of decision support currently reported. A LSP process T is described, its h complexity recognised, e and the problem domain defined. The evolution of the logistics strategy concept is addressed and defined a integrating procurement, production and distribution aspects. The need for decision support is also identified. A comprehensive review of models and modelling techniques from Management Science / Operations Research (MS/OR), and computer based tools in the LSP context is carried out. The appropriateness of the various models and types of computer tools is assessed. Gaps and drawbacks in current approaches to LSP are also identified. This revealed that past efforts have been directed towards producing more efficient solving techniques and tools for limited aspects of LSP, rather than developing models and tools that could address more realistic problems, recognising a integrated view of LSP. Hence, current approaches to LSP are fragmented in their handling of the procurement, production and distribution aspects. A conceptual modelling framework is proposed to support the LSP process. It includes a planning process, the logistics elements and key drivers required to define a model/representation of the LSP problem, and a selection of models/techniques to address various classes of LSP (sub-) problems. The framework provides a integrated view of all elements involved and contributes to formalise the knowledge necessary to address LSP problems. A modelling and decision support system is developed in order to demonstrate the framework and assess the approach here proposed to address practical LSP studies. STRATOVISION combines Visual Interactive Modelling (VIM) and Knowledge-Based (KB) techniques with "traditional" MS/OR models and modelling techniques. Additionally, the system implements a problem centred approach, combining various MS/OR solving techniques (e.g. simulation, heuristics and optimisation) into a unique modelling environment. A comparative analysis and discussion of functionality supports the view that STRATOVISION overcomes most limitations found with other modelling systems and provides better functionality to address LSP problems. The discussion covers the modelling phase, the options generation and the detailed evaluation of scenarios. Special emphasis is given both to the use of the Visual Interactive ( I) functionality for modelling and problem solving, and to the use of models/techniques included in STRATOVISION's model base. Several case studies are used to illustrate STRATOVISION's integrated approach to LSP and validate the model design. Comparison with fragmented approaches to LSP is carried out and the use of STRATOVISION in practical LSP studies including procurement, production and distribution decisions is reported. The analysis provides supporting evidence of the benefits achieved by using STRATOVISION's integrated approach to LSP. Finally, contributions of the approach are discussed and areas of further work pointed out.