D.Ing. (Electrical and Electronics Engineering) / This thesis treats aspects of the modelling techniques required for Computer Aided Design (CAD) of electromagnetically integrated structures for use in power electronic networks. The concept of structural impedance is introduced and developed, building on transmission line theory. Computer based methods for calculating the distributed parameters of a given structure are investigated. These methods are the Finite Element Method and the Incremental Method. Based on the structural impedance lumped element equivalent circuit models for interconnections are developed for modelling of the distributed energy storage effects associated with a physical circuit as part of a lumped element network that can be submitted to circuit simulation programs like SPICE. The models are used in SPICE circuit simulations of power circuits and the simulated results are verified experimentally. Circuit level simulation models for switches are investigated in order to determine the complexity and detail of models suitable for CAD of complete converter topologies. A classification scheme for circuit models of switches is developed as an aid in selection of suitable models for particular simulation purposes. A DC circuit model for power BJT's is developed as a theoretical exercise to determine the requirements, with regard to development time and computational resources, for application of a particular switch model. It is based on new ideas in an attempt to model the effects of power BJT operation of interest to power electronic circuit designers while decreasing the calculation requirements in comparison with sophisticated device physics based models normally used or over simplified models. Finally suggestions are made with regard to a new way of approaching the optimization of power conditioning circuits by using power flow as the basis. This includes the novel use of specially manufactured high permittivity dielectric materials to adjust the characteristic impedance of connections to obtain optimal operation under particular operating conditions.

No description available.

No description available.

He Jie. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 125-131). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iii / Contents --- p.v / Chapter Chapter 1 --- Research Introduction --- p.1 / Chapter 1.1 --- Background 1: Natural character of traditional China urban planning and its modern challenge --- p.2 / Chapter 1.2 --- "Background 2: Urban Natural Landscape Planning Approaches in China: Theory, Research and Practices" --- p.10 / Chapter 1.3 --- Visual Sustainability Research Definition in the Proposed Visual Landscape Analysis System --- p.17 / Chapter 1.4 --- Proposed Research Scope of the Thesis --- p.20 / Chapter Chapter 2 --- Literature Review of Landscape Evaluation and VIA Technologies --- p.22 / Chapter 2.1 --- Landscape Evaluation --- p.23 / Chapter 2.2 --- Visual Impact Assessment Technologies --- p.28 / Chapter 2.3 --- "CAD and GIS Approaches in Landscape Architecture, its Visualization Technologies and Visual Analysis" --- p.33 / Chapter Chapter 3 --- Research Methodology --- p.38 / Chapter 3.1 --- System Framework --- p.38 / Chapter 3.2 --- Theoretical Supporting --- p.43 / Chapter 3.3 --- Technology Supporting --- p.47 / Chapter Chapter 4 --- Case Study --- p.52 / Chapter 4.1 --- Introduction --- p.52 / Chapter 4.2 --- Primal Data Processing and Modeling --- p.57 / Chapter 4.3 --- Road Visual Perception Quality Evaluation of Qiwandao and Bo'ailu --- p.61 / Chapter 4.4 --- Visual Perception Assessment of Jinzishan Skyline --- p.95 / Chapter 4.5 --- Planner's Review and Physical Project Application --- p.110 / Chapter Chapter 5 --- Conclusion --- p.112 / Chapter 5.1 --- Accomplishment of the research --- p.112 / Chapter 5.2 --- "Shortcomings, problems and further opportunities" --- p.115 / Appendices --- p.120 / Appendix I. Comparative Table of Eight Sceneries of Yangcheng of Past Dynasties --- p.120 / Appendix II. Raw Data Resources of the Jinzishan Case Study --- p.122 / Appendix III. List of AutoCAD Blueprint Layer System of Jinzishan Case Study --- p.123 / Bibliography --- p.125

The design of 3D microwave devices can be improved by using computational optimization techniques combined with numerical simulations of the electromagnetic field. However, high accuracy field analysis is often computationally expensive and time consuming. One way to cut costs is to vary the accuracy level of the analysis at different stages of the optimization. This idea is based on the premise that the accuracy need not be constant throughout the optimization, and so the numerical analysis can be run more cheaply without compromising design quality. / This thesis presents a software system that minimizes the return loss of 3D microwave devices over a frequency band efficiently through accuracy control. It combines a custom gradient-based optimizer with a p-adaptive frequency-domain finite element solver. The solver computes the cost function and its gradient to a specified accuracy in a cost efficient manner. The p-adaptive solver comprises of two original components: an a-posteriori error estimator to evaluate the error in the cost function gradient, and an error indicator to identify the high error regions in the mesh. The optimizer controls the accuracy of the cost function evaluation through a link with the solver, specifying the required relative error for the gradient at each optimization step. / The combined adaption-optimization scheme was applied to 3D rectangular waveguide problems for validation: an E-plane miter bend, a U-bend, an impedance transformer and a compensated magic-T. For comparison, all the problems were also optimized using high-order finite elements at every step. Test results prove the computational efficiency of the new combined scheme at various stages of the optimization. In the early stages, when the element orders are low, the scheme is able to attain similar cost function reductions as the high-order analysis, with computational savings up to a factor of 25. Even in the late stages, when the accuracy is more stringent, the scheme manages a reduction in cumulative computation time of at least a factor of 4.

No description available.

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

No description available.

The era of VLSI design necessitates the development of advanced Computer Aided Design tools. The main objective of this research was to introduce an intelligent automatic Sequential Circuit Test System, SCIRTSS, driven by A Hardware Programming Language, AHPL. SCIRTSS can handle the test vector generation process for VLSI circuits in an early state of the design loop, even before the generation of the final technology dependent network logic list. The driving force of the test generation process is the intelligent search program. The search program, supported by a set of heuristics and an accurate function level simulator, generates the test sequence to propagate the single fault effect to a primary output of the circuit. The test sequence generated is a concatenation of the sequences generated by the repeated searches on the state-space of the design. These sequences are verified by a parallel fault simulator. Design for testability techniques could be used to improve the test sequence generated. This system is user friendly and protable. Several circuits were tested under SCIRTSS, the results of some of them were introduced in this paper.

No description available.