Les (sub)nanoclusters sont des agrégats d’atomes ou de molécules composés de quelques unités à quelques centaines d’unités. En raison de leur petite taille, ils peuvent avoir des propriétés électroniques, optiques, magnétiques et catalytiques très différentes par rapport au solide correspondant . D'un point de vue expérimental, il est encore très difficile de synthétiser des agrégats de taille calibrée. D'un point de vue théorique, le développement des puissances de calcul, des méthodes de calcul de structure électronique et des algorithmes de recherches globales de structures stables, permettent un calcul toujours plus précis de leurs propriétés physico-chimiques. L’étude théorique permet alors de déterminer de façon fiable les structures stables de ces systèmes qui président aux calculs de leurs propriétés . L’exemple qui illustre ce travail s’inspire du processus observé au sein des piles à combustible dans lequel le Platine (Pt) est couramment utilisé pour produire de l’énergie par oxydation du dihydrogène en favorisant notamment sa dissociation . L’objet de ce travail consiste à comparer la capacité des clusters de Platine de différentes tailles à adsorber la molécule de dihydrogène sous leur forme libre et adsorbée sur substrat. Le graphène , matériaux bidimensionnel cristallin formé de carbone est choisi dans ce travail en tant que substrat en raison de sa grande résistance mécanique et chimique. La première partie de ce travail est consacrée à la recherche d’éléments dopants qui vont permettent à la fois d’améliorer la capacité d’adsorption des clusters de Platine sur la surface et éviter leur migration. L’objectif est ici de proposer un substrat sur lequel peuvent être empêchés les phénomènes d’agglomération, de dissolution et de détachement du cluster qui ainsi limiteraient son efficacité catalytique . Des dopages de la surface, tel qu’ils sont réalisables expérimentalement , par l’Azote, le Bore et le Nitrure de Bore, par substitution atomique et avec ou sans considération préalable de lacunes, ont été étudiés. La seconde partie correspond à l’implémentation dans le code GSAM (Global Search Algorithm of Minima - algorithme de recherche globale de minima) développé au laboratoire , , des éléments qui permettent la recherche de structures de plus basse énergie de clusters moléculaires adsorbés sur substrat, tels que les systèmes [H2-Ptn-Graphène dopé] de cet exemple. La troisième partie concerne l’illustration de la fiabilité de la méthode de recherche globale employée et de la qualité de quelques méthodes de calcul de l’énergie moléculaire (DFT et GUPTA) vis-à-vis de résultats mentionnés dans la littérature sur les clusters de Platine. La dernière partie comporte l’investigation structurale des systèmes [H2-Ptn] et [H2-Ptn-Graphène dopé] pour différentes tailles de clusters allant de n=6 à n=20. La variation de l’énergie d’adsorption de H2 sur les clusters libres et supportés ainsi que celle du cluster moléculaire sur le substrat en fonction de la taille est reportée. / A sub-nanometer sized metal cluster consists of only several to tens of atoms. Due to its small size and quantum effects, it can have very specific electronic, optical, magnetic and catalytic properties as compared with their bulk behaviors . From an experimental point of view, it is still a big challenge to realize size-controlled synthesis for (sub) nanoclusters. From a theoretical point of view, benefiting from the development of faster high-performance computational sources, more efficient electronic structure modelling software and more reliable global search methods for the determination of the most stable structures, the chemical and physical properties of clusters can be determinate more accurately. As it is experimentally a big challenge to realize size-controlled synthesis for (sub) nanoclusters, theoretical studies can provide detailed information on their geometric structure, electronic structure, as well as adsorption and reaction properties . The example chosen to be treated in this study is inspired by the fuel cell, in which the Platinum (Pt) is a typical and most commonly used precious metal catalyst for the production of energy by the oxidation of dihydrogene . Graphene is a recently discovered 2D carbon net structure, has several special properties, such as: low weight, high strength, high surface area, high electrical conductivity, etc. With these properties and their novel combinations, graphene might prove a promising candidate to be used as catalyst supports. The first part of this study is devoted to the search of the doping elements which permit both enhance the adsorption capacity of Pt clusters on the surface and prevent their migration. The aim here is propose one substrate which can avoid the problems of cluster agglomeration, dissolution and detachment, which reduce the performance of the catalysts . The ways of doping of the surface, which have already been experimentally realized , such as Nitrogen, Boron, and N-B patches substitution of Carbon atoms with or without introducing the vacancy on the pristine graphene, are studied. The second part corresponds to the implementation of some new features into the code GSAM (Global Search Algorithm of Minima) developed in our laboratory , , , which permit the search of the most stable structures of the molecular clusters adsorbed on substrate, such as the complex systems of [H2-Ptn-doped Graphene]. The third part is to evaluate the reliabilities of the global search method used, as well as the DFT and the empirical (GUPTA) potential energy surface. Thus, the main discussion appears as a comparison with the results of the literature concerning the Pt clusters. The fourth part consists of the structural investigation of [H2-Ptn] and [H2-Ptn-doped Graphene] systems for different sizes of Pt clusters with n=6 to n=20. The variation of the adsorption energy of H2 on the free and supported Ptn clusters, and the adsorption energy of (H2+Ptn) system on the surface with respect to the size of the cluster is discussed.

Energetic polyatomic cluster beams are increasingly used in materials processing and surface analysis applications. In secondary ion mass spectrometry (SIMS) such beams have previously been utilised to investigate the chemical distribution of organic molecules (polymers, biological molecules and pharmaceuticals etc). One important application is in organic electronics, where the depth-distribution of organic components is important in the device performance. Massive gas cluster ion beams (GCIBs) have produced more successful depth-profiles for organic electronic devices that smaller projectiles including SF5+ and C60+. However, further work is needed to investigate and optimise experimental parameters to deliver the necessary SIMS performance. This study focused on molecular depth profiling of organic insulator (PMMA) and semiconductor (PTAA and TIPS-pentacene) materials, in single and bi-layered combinations, utilising cluster SIMS, using C60+ and Arn+, at different temperatures and energies. In general, at room temperature, the best depth resolution was obtained, using large Ar-GCIBs of low energy per atom (E/n ~10 eV), in comparison with the smaller Ar-GCIBs or with C60+ beams at the same total impact energy. On materials which sputtering under C60+ bombardment, ion and neutral yields were greatest due to the higher E/n, compared with GCIBs. Data from PMMA show that the sputter yield under C60 and Arn projectiles conform to the published 'universal' dependence of Y/n to E/n. Depth profiling of the semiconductor compounds were unsuccessful, using C60+ projectiles. For depth profiles using large GCIB projectiles, an increase in the secondary ion yield was observed at the interface with the silicon substrate - a phenomenon which was not observed for the smaller projectiles. In general, the most successful depth profiles (i.e. more constant molecular and fragment secondary ion yields, observed at pseudo-steady-state regions) and best depth resolutions were obtained at cryogenic temperatures - conditions under which corresponding sputtering yields and secondary ion yields were suppressed.

Wong Shu Yan. / On t.p. "n" is subscript. / Thesis submitted in: January 2003. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 112-115). / Abstracts in English and Chinese. / TITLE PAGE --- p.i / THESIS EXAMINATION COMMITTEE --- p.ii / ABSTRACT (ENGLISH) --- p.iii / (CHINESE) --- p.v / ACKNOWLEDGEMENTS --- p.vii / TABLE OF CONTENTS --- p.viii / LIST OF FIGURES --- p.xi / LIST OF TABLES --- p.xiii / Chapter CHAPTER ONE --- Introduction / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Solvation of clusters --- p.2 / Chapter 1.3 --- Reaction of a sodium atom with water --- p.3 / Chapter 1.4 --- Reaction of a sodium cation with methanol --- p.8 / Chapter 1.5 --- Computational Method --- p.12 / Chapter 1.5.1 --- Born-Oppenheimer (BO) Approximation --- p.12 / Chapter 1.5.2 --- Self-Consistent Fields (SCF) ´ؤ Hartree-Fock (HF) --- p.14 / Chapter 1.5.2.1 --- Moller-Plesset (MP) Perturbation Theory --- p.15 / Chapter 1.5.2.2 --- Ab Initio Molecular Orbital (MO) Calculation --- p.16 / Chapter 1.5.2.3 --- Basis Set Superposition Errors --- p.17 / Chapter 1.5.3 --- Density Functional Theory (DFT) --- p.18 / Chapter 1.5.3.1 --- Generalized-Gradient Approximation (GGA) --- p.20 / Chapter 1.5.3.2 --- Plane-wave Basis Set --- p.21 / Chapter 1.5.3.3 --- Pseudopotential Approximation --- p.21 / Chapter 1.5.3.4 --- Ab Initio Molecular Dynamics (MD) Calculation --- p.23 / Chapter CHAPTER TWO --- Reaction Mechanism of the Hydrogen Elimination Reaction of Na(H20)n clusters for n = 1 - 6 / Chapter 2.1 --- Introduction --- p.25 / Chapter 2.2 --- Computation details --- p.26 / Chapter 2.3 --- Optimized Structure of Na(H20)n and H.. .Na0H(H20)n-1 --- p.27 / Chapter 2.3.1 --- Solvation structures with n = 1-3 --- p.27 / Chapter 2.3.2 --- Solvation structures with n= 4-6 --- p.34 / Chapter 2.3.3 --- Relative energy of isomers --- p.40 / Chapter 2.3.4 --- Energy barrier of hydrogen elimination reaction --- p.42 / Chapter 2.3.5 --- Natural population analysis --- p.42 / Chapter 2.4 --- "Reaction energy for hydrogen loss in Na(H20)n, n = 1 -6" --- p.46 / Chapter 2.5 --- Ionization potential energy --- p.47 / Chapter 2.6 --- Summary --- p.50 / Chapter CHAPTER THREE --- Reaction Mechanism of the Ether Elimination Reaction of Na+(CH3OH)n cluster ions / Chapter 3.1 --- Introduction --- p.52 / Chapter 3.2 --- Computational details --- p.53 / Chapter 3.3 --- Optimized Structure for Na+(CH3OH)n (n = 1) --- p.55 / Chapter 3.4 --- Optimized Structure forNa+(CH3OH)n (n = 2-5) --- p.59 / Chapter 3.4.1 --- Na+(CH3OH)2 --- p.59 / Chapter 3.4.2 --- Na+(CH3OH)3 --- p.67 / Chapter 3.4.3 --- Na+(CH3OH)n(n = 4 and 5) --- p.75 / Chapter 3.5 --- Mechanism of ether elimination reaction --- p.79 / Chapter 3.6 --- Ab initio molecular dynamics study on Na+(CH3OH)n (n =6 and 8) --- p.85 / Chapter 3.6.1 --- Solvation dynamics for Na+(CH3OH)6 --- p.85 / Chapter 3.6.1.1 --- Dynamical structural for Na+(CH3OH)6 --- p.86 / Chapter 3.6.1.2 --- "Optimized Structures for Na+(CH3OH)n, n =6" --- p.95 / Chapter 3.6.2 --- Solvation dynamics for Na+(CH3OH)8 --- p.98 / Chapter 3.6.2.1 --- Dynamical structural for Na+(CH3OH)8 --- p.99 / Chapter 3.6.2.2 --- "Optimized Structures for Na+(CH3OH)n, n =8" --- p.106 / Chapter 3.7 --- Summary --- p.109 / REFERENCES --- p.112

by Ka-Kit Tse. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references. / Acknowledgments --- p.i / List of tables --- p.v / Chapter Chapter 1: --- Overall Review --- p.1 / Chapter Chapter 2: --- Essay one - A Mathematical Programming Approach to Clusterwise Regression Model and its Extensions / Chapter 2.0. --- Abstract --- p.5 / Chapter 2.1. --- Introduction --- p.6 / Chapter 2.2. --- A Mathematical Programming Formulation of the Clusterwise Regression Model --- p.10 / Chapter 2.2.1. --- The Generalized Clusterwise Regression Model --- p.10 / Chapter 2.2.2. --- "Clusterwise Regression Model (Spath, 1979)" --- p.14 / Chapter 2.2.3. --- A Nonparametric Clusterwise Regression Model --- p.15 / Chapter 2.2.4. --- A Mixture Approach to Clusterwise Regression Model --- p.16 / Chapter 2.2.5. --- An Illustrative Application --- p.19 / Chapter 2.3. --- Mathematical Programming Formulation of the Clusterwise Discriminant Analysis --- p.21 / Chapter 2.4. --- Conclusion --- p.25 / Chapter 2.5. --- Appendix --- p.28 / Chapter 2.6. --- References --- p.32 / Chapter 2.7. --- Tables --- p.35 / Chapter Chapter 3: --- Essay two - A Mathematical Programming Approach to Clusterwise Rank Order Logit Model / Chapter 3.0. --- Abstract --- p.40 / Chapter 3.1. --- Introduction --- p.41 / Chapter 3.2. --- Clusterwise Rank Order Logit Model --- p.42 / Chapter 3.3. --- Numerical Illustration --- p.46 / Chapter 3.4. --- Conclustion --- p.48 / Chapter 3.5. --- References --- p.50 / Chapter 3.6. --- Tables --- p.52 / Chapter Chapter 4: --- Essay three - A Mathematical Programming Approach to Metric Unidimensional Scaling / Chapter 4.0. --- Abstract --- p.53 / Chapter 4.1. --- Introduction --- p.54 / Chapter 4.2. --- Nonlinear Programming Formulation --- p.56 / Chapter 4.3. --- Numerical Examples --- p.60 / Chapter 4.4. --- Possible Extensions --- p.61 / Chapter 4.5. --- Conclusion and Extensions --- p.63 / Chapter 4.6. --- References --- p.64 / Chapter 4.7. --- Tables --- p.66 / Chapter Chapter 5: --- Research Project in Progress / Chapter 5.1. --- Project 1 -- An Integrated Approach to Taste Test Experiment Within the Prospect Theory Framework --- p.68 / Chapter 5.1.1. --- Experiment Procedure --- p.68 / Chapter 5.1.2. --- Experimental Result --- p.72 / Chapter 5.2. --- Project 2 -- An Integrated Approach to Multi- Dimensional Scaling Problem --- p.75 / Chapter 5.2.1. --- Introduction --- p.75 / Chapter 5.2.2. --- Experiment Procedure --- p.76 / Chapter 5.2.3. --- Questionnaire --- p.78 / Chapter 5.2.4. --- Experimental Result --- p.78

Lui Ying Kin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 63-65). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Introduction to bootstrap and efficiency bootstrap simulation --- p.5 / Chapter 2.1 --- Background of bootstrap --- p.5 / Chapter 2.2 --- Basic idea of bootstrap --- p.7 / Chapter 2.3 --- Variance reduction methods --- p.10 / Chapter 2.3.1 --- Control variates --- p.10 / Chapter 2.3.2 --- Common random numbers --- p.12 / Chapter 2.3.3 --- Antithetic variates --- p.14 / Chapter 2.3.4 --- Importance Sampling --- p.15 / Chapter 2.4 --- Efficient bootstrap simulation --- p.17 / Chapter 2.4.1 --- Linear approximation --- p.18 / Chapter 2.4.2 --- Centring method --- p.19 / Chapter 2.4.3 --- Balanced resampling --- p.20 / Chapter 2.4.4 --- Antithetic resampling --- p.21 / Chapter 3 --- Methodology --- p.22 / Chapter 3.1 --- Introduction --- p.22 / Chapter 3.2 --- Cluster analysis --- p.24 / Chapter 3.3 --- Regression estimator and mixture experiment --- p.25 / Chapter 3.4 --- Estimate of standard error and bias --- p.30 / Chapter 4 --- Simulation study --- p.45 / Chapter 4.1 --- Introduction --- p.45 / Chapter 4.2 --- Ratio estimation --- p.46 / Chapter 4.3 --- Time series problem --- p.50 / Chapter 4.4 --- Regression problem --- p.54 / Chapter 5 --- Conclusion and discussion --- p.60 / Reference --- p.63

No description available.

The thesis deals with the description and evaluation of the cluster analysis methodology and cluster policies as an adequate tool of growth in a region. Special emphasis is given to the work of M. Porter, which can be looked upon as a genesis of earlier research in the field and represents the current state of affairs in theoretical background and practical application. Also, the Czech republic as a case study is given a special section.

A presente Dissertação propõe uma biblioteca de comunicação de alto desempenho, baseada em troca de mensagens, especificamente projetada para explorar eficientemente as potencialidades da tecnologia SCI (Scalable Coherent Interface). No âmago da referida biblioteca, a qual se denominou DECK/SCI, acham-se três protocolos de comunicação distintos: um protocolo de baixa latência e mínimo overhead, especializado na troca de mensagens pequenas; um protocolo de propósito geral; e um protocolo de comunicação que emprega uma técnica de zero-copy, também idealizada neste Trabalho, no intuito de elevar a máxima largura de banda alcançável durante a transmissão de mensagens grandes. As pesquisas desenvolvidas no decurso da Dissertação que se lhe apresenta têm por mister proporcionar um ambiente para o desenvolvimento de aplicações paralelas, que demandam alto desempenho computacional, em clusters que se utilizam da tecnologia SCI como rede de comunicação. A grande motivação para os esforços envidados reside na consolidação dos clusters como arquiteturas, a um só tempo, tecnologicamente comparáveis às máquinas paralelas dedicadas, e economicamente viáveis. A interface de programação exportada pelo DECK/SCI aos usuários abarca o mesmo conjunto de primitivas da biblioteca DECK (Distributed Execution Communication Kernel), concebida originalmente com vistas à consecução de alto desempenho sobre a tecnologia Myrinet. Os resultados auferidos com o uso do DECK/SCI revelam a eficiência dos mecanismos projetados, e a utilização profícua das características de alto desempenho intrínsecas da rede SCI, haja visto que se obteve uma performance muito próxima dos limites tecnológicos impostos pela arquitetura subjacente. Outrossim, a execução de uma clássica aplicação paralela, para fins de validação, testemunha que as primitivas e abstrações fornecidas pelo DECK/SCI mantêm estritamente a mesma semântica da interface de programação do original DECK.

Chan, Hon Kit. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (p. 57-59). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Cluster Analysis in Time Series --- p.1 / Chapter 1.2 --- Dissimilarity Measure --- p.2 / Chapter 1.2.1 --- Euclidean Distance --- p.3 / Chapter 1.2.2 --- Pearson's Correlation Coefficient --- p.3 / Chapter 1.2.3 --- Other Measure --- p.4 / Chapter 1.3 --- Summary --- p.5 / Chapter 2 --- Algorithm and Methodology --- p.8 / Chapter 2.1 --- Algorithm and Methodology --- p.8 / Chapter 2.2 --- Illustrative Examples --- p.14 / Chapter 3 --- Simulation Study --- p.20 / Chapter 3.1 --- Simulation Plan --- p.20 / Chapter 3.2 --- Measure of Performance --- p.24 / Chapter 3.3 --- Simulation Results --- p.27 / Chapter 3.4 --- Results of k-means Clustering --- p.33 / Chapter 4 --- Application on Gene Expression --- p.37 / Chapter 4.1 --- Dataset --- p.37 / Chapter 4.2 --- Parameter Settings --- p.38 / Chapter 4.3 --- Results --- p.38 / Chapter 5 --- Conclusion and Further Research --- p.55

Bu, Yingyi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 89-94). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.v / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Anomaly Monitoring --- p.1 / Chapter 1.2 --- Privacy Preservation --- p.5 / Chapter 1.2.1 --- Motivation --- p.7 / Chapter 1.2.2 --- Contribution --- p.12 / Chapter 2 --- Anomaly Monitoring --- p.16 / Chapter 2.1 --- Problem Statement --- p.16 / Chapter 2.2 --- A Preliminary Solution: Simple Pruning --- p.19 / Chapter 2.3 --- Efficient Monitoring by Local Clusters --- p.21 / Chapter 2.3.1 --- Incremental Local Clustering --- p.22 / Chapter 2.3.2 --- Batch Monitoring by Cluster Join --- p.24 / Chapter 2.3.3 --- Cost Analysis and Optimization --- p.28 / Chapter 2.4 --- Piecewise Index and Query Reschedule --- p.31 / Chapter 2.4.1 --- Piecewise VP-trees --- p.32 / Chapter 2.4.2 --- Candidate Rescheduling --- p.35 / Chapter 2.4.3 --- Cost Analysis --- p.36 / Chapter 2.5 --- Upper Bound Lemma: For Dynamic Time Warping Distance --- p.37 / Chapter 2.6 --- Experimental Evaluations --- p.39 / Chapter 2.6.1 --- Effectiveness --- p.40 / Chapter 2.6.2 --- Efficiency --- p.46 / Chapter 2.7 --- Related Work --- p.49 / Chapter 3 --- Privacy Preservation --- p.52 / Chapter 3.1 --- Problem Definition --- p.52 / Chapter 3.2 --- HD-Composition --- p.58 / Chapter 3.2.1 --- Role-based Partition --- p.59 / Chapter 3.2.2 --- Cohort-based Partition --- p.61 / Chapter 3.2.3 --- Privacy Guarantee --- p.70 / Chapter 3.2.4 --- Refinement of HD-composition --- p.75 / Chapter 3.2.5 --- Anonymization Algorithm --- p.76 / Chapter 3.3 --- Experiments --- p.77 / Chapter 3.3.1 --- Failures of Conventional Generalizations --- p.78 / Chapter 3.3.2 --- Evaluations of HD-Composition --- p.79 / Chapter 3.4 --- Related Work --- p.85 / Chapter 4 --- Conclusions --- p.87 / Bibliography --- p.89