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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Computer-aided control system design using optimization methods

Grace, A. C. W. January 1989 (has links)
Control System Design methods are presented in terms of optimization techniques that incorporate Multi-Objective design criteria. Computer-Aided Control System Design (CACSD) environments make the approach easy-to-use and accessible to the practising control engineer. Two CACSD environments have been developed using different versions of the MATLAB package, one interfacing the ADS optimization package to an upgraded FORTRAN version of MATLAB, the other using Non-linear Programming algorithms coded in the PRO-MATLAB command language. In both environments, optimization problems are entered interactively and in a flexible manner using simple interpreted commands and programs. A Control System Design method has been implemented using optimal control theory and integral quadratic measures of control. The theory has been developed to incorporate a large number of design options, control structures and disturbance types. An evolutionary design process is used so that the control order and number of design criteria are systematically increased to incorporate more complex control structures and a wide set of performance objectives. In the later stages of this evolutionary design process, a Multi-Objective design strategy, known as the Goal Attainment method, is used to address multiple performance objectives.
202

Computer graphics studies of Islamic geometrical patterns and designs

Salman, Amer Shaker January 1991 (has links)
This thesis results from the following work: (1) We have carried out a comprehensive study of Islamic geometrical patterns. More then 300 patterns have been studied. We have given a critique of the work of previous authors on this subject and have discussed our own Ideas on the evolution of Islamic geometrical designs. (2) We have performed symmetry analysis on the patterns and classified them according to their symmetry groups. (3) We have extracted numerical data for efficient generation of the patterns based on the analysis In (2). The data for more than 300 patterns Is provided on the disk. (4) We have developed a mathematical formalism based on group theory and constructed algorithms suitable for the generation of the patterns using computer graphics. (5) the algorithms have been proved by writing an Interactive computer graphic program called Islamic Geometrical Patterns ' IGP'. A library of geometric Islamic patterns has been constructed. (6) At Lite end of this thesis, In an Appendix, we have provided suggestions for further extension of this work.
203

Computer-aided design and simulation of fibre optic systems for power system protection

Li, Haiyu January 1994 (has links)
No description available.
204

Manufacturing information for engineering design

Chen, Weng-Jen January 1998 (has links)
No description available.
205

Computer mediated colour fidelity and communication

Rhodes, Peter A. January 1995 (has links)
Developments in technology have meant that computercontrolled imaging devices are becoming more powerful and more affordable. Despite their increasing prevalence, computer-aided design and desktop publishing software has failed to keep pace, leading to disappointing colour reproduction across different devices. Although there has been a recent drive to incorporate colour management functionality into modern computer systems, in general this is limited in scope and fails to properly consider the way in which colours are perceived. Furthermore, differences in viewing conditions or representation severely impede the communication of colour between groups of users. The approach proposed here is to provide WYSIWYG colour across a range of imaging devices through a combination of existing device characterisation and colour appearance modeling techniques. In addition, to further facilitate colour communication, various common colour notation systems are defined by a series of mathematical mappings. This enables both the implementation of computer-based colour atlases (which have a number of practical advantages over physical specifiers) and also the interrelation of colour represented in hitherto incompatible notations. Together with the proposed solution, details are given of a computer system which has been implemented. The system was used by textile designers for a real task. Prior to undertaking this work, designers were interviewed in order to ascertain where colour played an important role in their work and where it was found to be a problem. A summary of the findings of these interviews together with a survey of existing approaches to the problems of colour fidelity and communication in colour computer systems are also given. As background to this work, the topics of colour science and colour imaging are introduced.
206

A STEP-based generic mechanical model of electronic products

Moustapha, Imad January 1997 (has links)
This thesis adopts the new STEP standard and accompanying methodologies to solve an important problem facing manufacturing industries: integrating CAD tools and product data information. Using the STEP methodology, a first attempt to develop a multi-Application Protocol application was made, which led to the development of a generic electronic product model that became the conceptual schema of an object oriented database. This model has been actually implemented and tested. The methodology adopted led to the proposal of a new extended Application Protocol designed to meet information requirements of the manufacture of electronic products. The generic model for electronic products is proposed and developed employing STEP resources and methodologies. Using STEP's information modelling language, EXPRESS, extra data constructs were developed to satisfy the information requirements of the model. Novel aspects of the model include: the combination of all aspects of the product, both electronic and mechanical; and the extension of the model over six different STEP Application Protocols. The work involved the proposal of a new extended Application Protocol to meet information requirements of electronic products, and the development of a detailed model of a generic Printed Circuit Board (PCB). A unique feature of this PCB model is its compatibility with any future PCB CAD tool claiming compliance to STEP. The models conformance to STEP was ensured via extensive validation and conformance procedures. Problems related to the implementation of this new standard in the electronics industry were identified and possible solutions discussed. This work includes an industrial case study where an actual activity model of an engineering organisation was developed; the proposed generic model implemented and tested; and the actual data instances of a product generated and stored in a universal object-oriented product database. The implementation of the generic model provided the engineering organisation with an integrated platform for product data, which facilitated the implementation of concurrent engineering practices.
207

Functional interaction : diagnosing interface relationships in new product development

Jones, Tim January 1998 (has links)
This thesis describes the development of a diagnostic tool to identify potential weaknesses in the interfaces between the key functions involved in new product development within manufacturing organisations. It comprises three parts: Part One introduces the field and reviews the literature. It discusses the subject of new product development (NPD), describes how the NPD process has evolved and outlines the key success factors which have been found to apply. It identifies and summarises the key issues which have influenced NPD and discusses the role that teams have had within the field. Key functions and their respective interfaces are identified and the barriers which exist between these functions assessed. A theoretical framework is presented which proposes that problems within these functional interfaces can be overcome by developing appropriate solutions based on accurate diagnosis of imbalance of functional perceptions within organisations. Associated research hypotheses and methodology for the research programme are also presented. Part Two describes the development and testing of a questionnaire to achieve this diagnosis. This details the identification of core issues through interviews in sample companies, initial testing of a questionnaire and the subsequent revision and retesting. Rationalisation of the questionnaire using both item and factor analysis techniques are then described and, following final testing, the use of these same techniques to develop a scoring system are also detailed. Part Three discusses the findings from the research programme and draws conclusions. The results obtained from the use of the diagnostic questionnaire within the participating organisations are compared with the literature and the development of the diagnostic questionnaire is evaluated. Finally the research hypotheses are examined and tested and conclusions relating to both the findings and the questionnaire development are drawn. Finally recommendations for the future use of the developed diagnostic tool are made.
208

Computer-aided optimal open pit design with variable slope angles

Khalokakaie, Reza January 1999 (has links)
The use of open pit mining has increased to extract large and low grade deposits with the growth in demand for raw materials, with the advances in mining technology and with the depletion of high grade and readily accessible orebodies. Development and extraction of minerals by this method is a complex operation that may extend over several decades and require very large investments. Before starting the operation, it is necessary to design the size and final shape of the pit in order to determine minable reserves and amount of waste to be removed. It is also needed to locate the waste dump, processing plant, access roads and to develop a production program. The ultimate pit limit depends upon many factors. One of the most important factors is the pit slopes which affect the stripping ratio and amounts of waste to be removed. When dealing with complex deposits in which the pit slopes may vary in different parts of the orebody due to slope stability requirements, it is necessary to take into account variable pit slopes in the designing of the pit limit. Determination of the pit limit 'in open pit mining is one of the ' most important design factors which may be considered many times during the life of the mine as the design parameters change in the future or more information is obtained during the operation. Therefore the use of a computer is essential in order to design the pit as rapidly as possible. As a result, a number of algorithms such as the various versions of the moving cone method, Lerchs-Grossmann algorithm, network or maximal flow techniques, Korobov algorithm, dynamic programming and parameterization techniques have been developed to determine the optimum ultimate pit limit since the advent and wide spread use of computers. The main objective of these algorithms is to determine the optimum pit limit in order to maximise the overall mining profit within the designed pit limit subject to the mining constraints. Of these, the Lerchs-Grossmann algorithm is well known for being the only method which always yields the true optimum pit limit. However, the algorithm which utilises graph theory was based on fixed slope angles that are governed by the block dimensions when it was introduced. In spite of the fact that many attempts have been made to incorporate variable slope angles, none of them provide an adequate solution where there are, variable slopes controlled by complex structures and geology. This algorithm is reconsidered and modified to deal with variable slope angles. It is assumed that the orebody and the surrounding waste are divided into regions or domain sectors within which the rock characteristics are the same and each region is specified by four principal slope angles including North, South, East and West face slope angles. Consequently slope angles can vary through the deposit to follow the rock characteristics and are independent of the block dimensions. In addition, two methods were also developed to estimate the four principal slope angles from geotechnical information to use as input parameters in the optimal pit, design algorithm. A general PC software was also developed to determine the optimum pit limit with variable slope angles for an open pit mine. The software is a Windows application that'can be implemented under 32-bit operating systems such as. Windows 95, Windows NT and. Windows 98. It is capable of taking advantage of all the computer memory and designing the optimum pit limit for complex, large and low grade deposits due to solving the memory limitation. The software includes both graphical and numerical presentation of the, input data and the results of optimisation. Two case studies have been used to validate the software developed.
209

Graphical modelling of modular machines

Yan, Xiu Tan January 1992 (has links)
This research is aimed at advancing machine design through specifying and implementing (in "proof of concept" form) a set of tools which graphically model modular machines. The tools allow mechanical building elements (or machine modules) to be selected and configured together in a highly flexible manner so that operation of the chosen configuration can be simulated and performance properties evaluated. Implementation of the tools has involved an extension in capability of a proprietary robot simulation system. This research has resulted in a general approach to graphically modelling manufacturing machines built from modular elements. A focus of study has been on a decomposition of machine functionality leading to the establishment of a library of modular machine primitives. This provides a useful source of commonly required machine building elements for use by machine designers. Study has also focussed on the generation of machine configuration tools which facilitate the construction of a simulation model and ultimately the physical machine itself. Simulation aspects of machine control are also considered which depict methods of manipulating a machine model in the simulation phase. In addition methods of achieving machine programming have been considered which specify the machine and its operational tasks. Means of adopting common information data structures are also considered which can facilitate interfacing with other systems, including the physical machine system constructed as an issue of the simulation phase. Each of these study areas is addressed in its own context, but collectively they provide a means of creating a complete modular machine design environment which can provide significant assistance to machine designers. Part of the methodology employed in the study is based on the use of the discrete event simulation technique. To easily and effectively describe a modular machine and its activity in a simulation model, a hierarchical ring and tree data structure has been designed and implemented. The modularity and reconfigurability are accommodated by the data structure, and homogeneous transformations are adopted to determine the spatial location and orientation of each of the machine elements. A three-level machine task programming approach is used to describe the machine's activities. A common data format method is used to interface the machine design environment with the physical machine and other building blocks of manufacturing systems (such as CAD systems) where systems integration approaches can lead to enhanced product realisation. The study concludes that a modular machine design environment can be created by employing the graphical simulation approach together with a set of comprehensive configuration. tools. A generic framework has been derived which outlines the way in which machine design environments can be constructed and suggestions are made as to how the proof of concept design environment implemented in this study can be advanced.
210

Design guideline support for manufacturability

Nowack, Mark Lorenz January 1997 (has links)
Matching the configuration of a product to available production capabilities during the design process directly affects product cost and hence product competitiveness. Existing approaches to improving manufacturability are helpful in the latter stages of the design process and usually involve corrective redesign. To avoid redesign, designers require appropriate guidance in the early stages of the design process. Guidelines, that is prescriptive recommendations for actions to address issues, are frequently used to provide this guidance. However, guideline sets are often poorly structured, incomplete, and the guidelines difficult to retrieve and apply. The overall aim of this research is to improve guidance to designers, particularly manufacturability guidance, early in the design process. Particular objectives of this research are to improve existing methods of guideline collection, storage, and retrieval. The research proceeded in the following pattern: - Case studies explored manufacturability problems in a small company. - Guideline support concepts were developed using a retrospective case study. - Collection concepts were developed with observational studies. - Storage approaches were developed using advanced composite guidelines. - A link-based retrieval technique was validated with a mechanical design protocol study. - Collection, storage, and retrieval methods were empirically tested. The results of this research were: - a technique to directly relate guidelines to the design process - a system of links relating guidelines to each other - an Action-Centred Guideline Approach - a preliminary software implementation of the approach - validation of the utility of the approach. The conclusions from this research are: - Guidance in the early stages of the design process can be improved through the use of structured guidelines. - The Action-Centred Guideline Approach improves the collection, storage, and retrieval of guidelines. - Empirical validation showed that guideline links are an effective means for improving guideline retrieval. - Further research is required in the areas of integrating the approach with other design tools, and in extending the link technique.

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