published_or_final_version / abstract / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Architecture / Doctoral / Doctor of Philosophy

This thesis studies the application of sensitivity analysis and optimization methods to the design of turbomachinery components. Basic design issues and a survey of current design trends are presented. The redesign of outlet guide vanes (OGV's) in an aircraft high bypass turbofan engine is attempted. The redesign is necessitated by the interaction of the pylon induced static pressure field with the OGV's and the fan, leading to reduced OGV efficiency and shortened fan life. The concept of cyclically varying camber is used to redesign the OGV row to achieve suppression of the downstream disturbance in the domain upstream of the OGV row. The redesign is performed using (a) a linear perturbation CFD analysis and (b) a minimisation of the pressure mismatch integral by using a Newton method. In method (a) the sensitivity of the upstream flow field to changes in blade geometry is acquired from the linear perturbation CFD analysis, while in method (b) it is calculated by perturbing the blade geometry and differencing the resulting flow fields. Method (a) leads to a reduction in the pylon induced pressure variation at the fan by more than 70% while method (b) achieves up to 86%. An OGV row with only 3 different blade shapes is designed using the above method and is found to suppress the pressure perturbation by more than 73%. Results from these calculations are presented and discussed. The quasi-Newton design method is also used to redesign a three dimensional OGV row and achieves considerable reduction of upstream pressure variation. A concluding discussion summarises the experiences and suggests possible avenues for further work.

A utilização da programação "off-line" para robôs é reconhecidamente um procedimento útil em automação industrial, uma vez que possibilita o desenvolvimento de novos programas e a realização de testes de configurações no "workspace" do robô sem comprometimento do tempo de sua utilização, realizando-se conseqüentemente, tarefas de baixo custo, e tempo reduzido. A programação off-line necessita que haja a correspondência dos dados geométricos entre o modelo "off-line" obtido em CAD e o espaço de trabalho do manipulador real. Para que isso ocorra, é preciso fazer a calibração da interface robô-CAD, de maneira a garantir correspondência entre software (modelo CAD/programa off-line) e máquina (manipulador/espaço de trabalho). Atualmente esta calibração é feita de maneira "ad hoc", não sistematizada, acarretando uma carga de trabalho adicional para o operador. Como uma solução alternativa a esse problema, é proposto neste trabalho um procedimento para a calibração desta interface, de maneira a validar os resultados obtidos na programação "off-line", tornando o procedimento menos dependente da intervenção do operador. Este procedimento foi elaborado visando a sua utilização na programação "off-line" de robôs em nível de tarefa, cujo objetivo é aumentar o grau de "inteligência" dos robôs, principalmente em aplicações de montagem. Uma montagem experimental para validação dos resultados foi implementada utilizando o manipulador PUMA 560 da Unimation e o aplicativo CAD, AutoCAD. Os resultados obtidos mostraram que o procedimento proposto pode ser usado com sucesso em aplicações industriais.

Chow Chi Kin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 136-139). / Text in English; abstracts in English and Chinese. / Chow Chi Kin. / Abstract --- p.i / 摘要 --- p.ii / Acknowledgement --- p.iii / Table of content --- p.iv / List of figures --- p.viii / Chapter Chapter 1: --- Introduction --- p.1 / Chapter Chapter 2: --- What is Surface Registration? --- p.7 / Chapter 2.1 --- What is free-form surface --- p.7 / Chapter 2.2 --- Methodologies of surface construction --- p.8 / Chapter 2.2.1 --- CAD Model --- p.9 / Chapter 2.2.2 --- 3D Reconstruction algorithm --- p.11 / Chapter 2.2.3 --- Geometric/Range sensors --- p.12 / Chapter 2.3 --- What is Surface Registration --- p.14 / Chapter 2.4 --- Purpose of Surface Registration --- p.19 / Chapter 2.5 --- Review of exist registration algorithms --- p.20 / Chapter 2.5.1 --- ICP (Iterative Closest Point) algorithm --- p.20 / Chapter A. --- Overview of ICP --- p.21 / Chapter B. --- ICP Kernel --- p.22 / Chapter C. --- Possible pre-processings of ICP --- p.23 / Chapter D. --- Multiple features in the closest point search --- p.24 / Chapter E. --- Advantages of ICP --- p.25 / Chapter F --- . Disadvantages of ICP --- p.26 / Chapter 2.5.2 --- "Feature-based, registration" --- p.27 / Chapter 2.5.3 --- Genetic algorithm approach --- p.28 / Chapter Chapter 3: --- What is Genetic Algorithm? --- p.32 / Chapter 3.1 --- What is Genetic Algorithm (GA) --- p.32 / Chapter 3.2 --- Exists Search Methods --- p.33 / Chapter 3.3 --- Mechanism of Genetic Algorithms --- p.39 / Chapter 3.3.1 --- Initialization --- p.41 / Chapter 3.3.2 --- Reproduction --- p.41 / Chapter A. --- Cross-Over --- p.42 / Chapter B. --- Mutation --- p.44 / Chapter 3.3.3 --- Selection --- p.47 / Chapter A. --- Best Fitness Selection --- p.47 / Chapter B. --- Probabilistic Selection --- p.49 / Chapter 3.3.4 --- Termination checking --- p.52 / Chapter A. --- Fixed number of generation --- p.53 / Chapter B. --- Adaptive number of generation --- p.53 / Chapter 3.3.5 --- Solution Space --- p.54 / Chapter 3.3.6 --- Formation of chromosome --- p.54 / Chapter 3.3.7 --- Fitness function --- p.55 / Chapter 3.4 --- Examples of function optimization using Genetic Algorithm --- p.55 / Experiment 1: 2D Sphere function --- p.56 / Experiment 2: 2D Sinc function --- p.58 / Experiment 3: Foxholes function --- p.61 / Experiment 4: Steps Exponential Decay function --- p.63 / Chapter 3.5 --- Convergence Theorem of Genetic Algorithm --- p.66 / Chapter Chapter 4: --- Surface Registration as an Optimization --- p.71 / Chapter 4.1 --- Solution space --- p.75 / Chapter 4.2 --- Formation of Gene and Chromosome --- p.79 / Chapter 4.3 --- Fitness Function --- p.83 / Chapter 4.4 --- Genetic Algorithm VS. Steepest Gradient Descent --- p.88 / Chapter 4.5 --- Reproduction --- p.94 / Chapter 4.5.1 --- Cross-Over --- p.94 / Chapter 4.5.2 --- Mutation --- p.95 / Chapter 4.5.3 --- Variant --- p.95 / Chapter 4.6 --- Selection --- p.101 / Chapter 4.7 --- Dynamic Boundary --- p.103 / Chapter 4.8 --- Nearest Neighbor Search --- p.108 / Chapter Chapter 5: --- Experimental Results --- p.112 / Chapter 5.1 --- Surface Registration --- p.113 / Chapter 5.2 --- Model Integration --- p.114 / Chapter A. --- Human skull --- p.115 / Chapter B. --- Easter Island stone --- p.115 / Chapter C. --- Child --- p.116 / Chapter D. --- Dinosaur head --- p.116 / Chapter 5.3 --- Noise Sensitivity --- p.117 / Chapter 5.3.1 --- Addition of Gaussian noise --- p.117 / Chapter A. --- Human Skull --- p.117 / Chapter B. --- Human foot bone --- p.119 / Chapter C. --- Human heart --- p.120 / Chapter D. --- Human vertebrae --- p.122 / Chapter E. --- Human fetus --- p.125 / Chapter 5.3.2 --- Smoothing of pre-added Gaussian noise --- p.127 / Chapter A. --- Human skull --- p.128 / Chapter B. --- Human foot bone --- p.129 / Chapter 5.4 --- Model Integration of Real Images --- p.130 / Chapter Chapter 6: --- Conclusion --- p.133 / References --- p.136

Ma Mun Chung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 86-88). / Abstract also in Chinese. / Abstract --- p.i / Declaration --- p.ii / Acknowledgement --- p.iii / List of Figures --- p.iv / List of Tables --- p.ix / Table of Contents --- p.x / Chapter 1. --- Introduction --- p.1 / Chapter 1.1. --- Motivation --- p.1 / Chapter 1.2. --- Thesis Roadmap --- p.3 / Chapter 1.3. --- Contribution / Chapter 2. --- System Architecture --- p.6 / Chapter 2.1. --- Tracker system --- p.6 / Chapter 2.1.1. --- Spatial Information --- p.6 / Chapter 2.1.2. --- Transmitter (Xmtr) --- p.6 / Chapter 2.1.3. --- Receiver (Recvr) --- p.7 / Chapter 2.2. --- Glove System --- p.7 / Chapter 2.2.1. --- CyberGlove Interface Unit (CGIU) --- p.7 / Chapter 2.2.2. --- Bend Sensors --- p.7 / Chapter 2.3. --- Integrating the tracker and the glove system --- p.9 / Chapter 2.3.1. --- System Layout --- p.9 / Chapter 3. --- Deformable Model --- p.11 / Chapter 3.1. --- Elastic models in computer --- p.11 / Chapter 3.2. --- Virtual object model --- p.17 / Chapter 3.3. --- Force displacement relationship --- p.18 / Chapter 3.3.1. --- Stress-strain relationship --- p.19 / Chapter 3.3.2. --- Stiffness matrix formulation --- p.20 / Chapter 3.4. --- Solving the linear system --- p.24 / Chapter 3.5. --- Implementation --- p.26 / Chapter 3.5.1. --- Data structure --- p.26 / Chapter 3.5.2. --- Global stiffness matrix formulation --- p.27 / Chapter 3.5.3. --- Re-assemble of nodal displacement --- p.30 / Chapter 4. --- Collision Detection --- p.32 / Chapter 4.1. --- Related Work --- p.31 / Chapter 4.2. --- Spatial Subdivision --- p.37 / Chapter 4.3. --- Hierarchy construction --- p.38 / Chapter 4.3.1. --- Data structure --- p.39 / Chapter 4.3.2. --- Initialisation --- p.41 / Chapter 4.3.3. --- Expanding the hierarchy --- p.42 / Chapter 4.4. --- Collision detection --- p.45 / Chapter 4.4.1. --- Hand Approximation --- p.45 / Chapter 4.4.2. --- Interference tests --- p.47 / Chapter 4.4.3. --- Searching the hierarchy --- p.51 / Chapter 4.4.4. --- Exact interference test --- p.51 / Chapter 4.5. --- Grasping mode --- p.53 / Chapter 4.5.1. --- Conditions for Finite Element Analysis (FEA) --- p.53 / Chapter 4.5.2. --- Attaching conditions --- p.53 / Chapter 4.5.3. --- Collision avoidance --- p.54 / Chapter 4.6. --- Repeating deformation in different orientation --- p.56 / Chapter 5. --- Enhancing performance --- p.59 / Chapter 5.1. --- Data communication --- p.60 / Chapter 5.1.1. --- Client-server model --- p.60 / Chapter 5.1.2. --- Internet protocol suite --- p.61 / Chapter 5.1.3. --- Berkeley socket --- p.61 / Chapter 5.1.4. --- Checksum problem --- p.62 / Chapter 5.2. --- Use of parallel tool --- p.62 / Chapter 5.2.1. --- Parallel code generation --- p.63 / Chapter 5.2.2. --- Optimising parallel code --- p.64 / Chapter 6. --- Implementation and Results --- p.65 / Chapter 6.1. --- Supporting functions --- p.65 / Chapter 6.1.1. --- Read file --- p.66 / Chapter 6.1.2. --- Keep shape --- p.67 / Chapter 6.1.3. --- Save as --- p.67 / Chapter 6.1.4. --- Exit --- p.67 / Chapter 6.2. --- Visual results --- p.67 / Chapter 6.3. --- An operation example --- p.75 / Chapter 6.4. --- Performance of parallel algorithm --- p.78 / Chapter 7. --- Conclusion and Future Work --- p.84 / Chapter 7.1. --- Conclusion --- p.84 / Chapter 7.2. --- Future Work --- p.84 / Reference --- p.86 / Appendix A Matrix Inversion --- p.89 / Appendix B Derivation of Equation 6.1 --- p.92 / Appendix C Derivation of (6.2) --- p.93

Ho Chi Kit. / Thesis submitted in: September 2005. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 66-70). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.9 / Chapter 1.1 --- Aims and Contribution --- p.9 / Chapter 1.2 --- Dissertation Overview --- p.10 / Chapter 2 --- Literature Review --- p.11 / Chapter 2.1 --- ATPG-based Alternative Wiring --- p.11 / Chapter 2.1.1 --- Post-Layout Logic Restructuring for Performance Optimization --- p.11 / Chapter 2.1.2 --- Timing Optimization by an Improved Redundancy Addition and Removal Technique --- p.12 / Chapter 2.2 --- Logic Synthesis --- p.13 / Chapter 2.2.1 --- Local Logic Substitution Algorithm for Post-Layout Re-synthesis --- p.13 / Chapter 2.2.2 --- SIS: A System for Sequential Circuit Synthesis --- p.13 / Chapter 2.3 --- Fanout Optimization --- p.14 / Chapter 2.3.1 --- Efficient Global Fanout Optimization Algorithms --- p.14 / Chapter 2.3.2 --- Fanout Optimization under a Submicron Transistor-Level Delay Model --- p.15 / Chapter 2.4 --- Genetic Algorithm --- p.15 / Chapter 2.4.1 --- Scalability and Efficiency of Genetic Algorithms for Geometrical Applications --- p.15 / Chapter 2.4.2 --- "The Gambler's Ruin Problem, Genetic Algorithms, and the Sizing of Populations" --- p.16 / Chapter 3 --- Background --- p.18 / Chapter 3.1 --- Redundancy Addition and Removal --- p.18 / Chapter 3.2 --- REWIRE --- p.19 / Chapter 4 --- Standard Cell Logic Synthesis --- p.20 / Chapter 4.1 --- Introduction --- p.20 / Chapter 4.2 --- Objective --- p.22 / Chapter 4.3 --- Use Standard Patterns for Logic Synthesis --- p.22 / Chapter 4.4 --- Optimization --- p.25 / Chapter 4.5 --- Proposed Scheme --- p.26 / Chapter 4.6 --- Criteria for Selection of Wire --- p.28 / Chapter 4.7 --- Experimental Results --- p.30 / Chapter 4.8 --- Conclusion --- p.34 / Chapter 5 --- Theory on GBAW --- p.35 / Chapter 5.1 --- Introduction --- p.35 / Chapter 5.2 --- Notations and Definitions --- p.36 / Chapter 5.3 --- Minimality and Duality --- p.37 / Chapter 5.4 --- Topological Property of GBAW patterns --- p.41 / Chapter 5.5 --- Experimental Results --- p.47 / Chapter 5.6 --- Conclusion --- p.51 / Chapter 6 --- Multi-way GBAW Partitioning Scheme --- p.52 / Chapter 6.1 --- Introduction --- p.52 / Chapter 6.2 --- Algorithm of GBAW Partitioning Scheme --- p.55 / Chapter 6.3 --- Experimental Results --- p.56 / Chapter 6.4 --- Conclusion --- p.63 / Chapter 7 --- Conclusion --- p.64 / Bibliography --- p.66

Kwok, Tsz Ho. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 161-175). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

Engineering design involves a series of activities to handle data, including capturing and storing data, retrieval and manipulation of data. This also applies throughout the entire product lifecycle (PLC). Unfortunately, a closed loop of knowledge and information management system has not been implemented for the PLC. As part of product lifecycle management (PLM) approaches, computer-aided design (CAD) systems are extensively used from embodiment and detail design stages in mechanical engineering. However, current CAD systems lack the ability to handle semantically-rich information, thus to represent, manage and use knowledge among multidisciplinary engineers, and to integrate various tools/services with distributed data and knowledge. To address these challenges, a general-purpose semantic annotation approach based on CAD systems in the mechanical engineering domain is proposed, which contributes to knowledge management and reuse, data interoperability and tool integration. In present-day PLM systems, annotation approaches are currently embedded in software applications and use diverse data and anchor representations, making them static, inflexible and difficult to incorporate with external systems. This research will argue that it is possible to take a generalised approach to annotation with formal annotation content structures and anchoring mechanisms described using general-purpose ontologies. In this way viewpoint-oriented annotation may readily be captured, represented and incorporated into PLM systems together with existing annotations in a common framework, and the knowledge collected or generated from multiple engineering viewpoints may be reasoned with to derive additional knowledge to enable downstream processes. Therefore, knowledge can be propagated and evolved through the PLC. Within this framework, a knowledge modelling methodology has also been proposed for developing knowledge models in various situations. In addition, a prototype system has been designed and developed in order to evaluate the core contributions of this proposed concept. According to an evaluation plan, cost estimation and finite element analysis as case studies have been used to validate the usefulness, feasibility and generality of the proposed framework. Discussion has been carried out based on this evaluation. As a conclusion, the presented research work has met the original aim and objectives, and can be improved further. At the end, some research directions have been suggested.