Wang, Xiaohui. / "November 1999." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Predicting the temperature-strain phase diagram of VO$_2$, including the various structural allotropes, from first principles is a grand challenge of materials physics, and even the phase diagram remains unclear at T = 0K. The coexistence of Peierls and Mott physics suggests that a theory which can capture strong electronic correlations will be necessary to compute the total energies. In order to understand the complex nature of the first-order transition of VO$_2$, we build a minimal model of the structural energetics using the Peirels-Hubbard model and solve it exactly using the Density Matrix Renormalization Group (DMRG) methods demonstrating that the on-site interaction $U$ has a minimal effect on the structural energetics for physical parameters. These results explain the qualitative failures of Density Functional Theory (DFT) and DFT+$U$ for the structural energetics, in addition to the partial success of the unorthodox DFT+$U$ results (i.e. non-spin-polarized and small $U$). It also guides the creation of empirical corrections to the DFT+$U$ functional which allow us to semi-quantitatively capture the phase stability of the rutile and monoclinic phases as a function of temperature and strain. Our work demonstrates that VO$_2$ is better described as a Mott assisted Peierls transition.

Lee Sim Heung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Abstracts in English and Chinese. / ABSTRACT --- p.i / ACKNOWLEGEMENT --- p.vi / LIST OF FIGURES --- p.xi / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1. --- New challenges in telecommunication --- p.2 / Chapter 1.2. --- Introduction to optical non-linearity and its impact to optical network --- p.3 / Chapter 1.3. --- Applications of optical nonlinearity --- p.5 / Chapter 1.3.1. --- Extinction ratio enhancement and wavelength conversion --- p.5 / Chapter 1.3.2. --- All optical ASK to DPSK converter --- p.6 / Chapter 1.3.3. --- All-optical RZ to NRZ format converter --- p.8 / Chapter 1.3.4. --- RF clock component enhancement for NRZ data --- p.10 / Chapter 1.3.5. --- Multi-wavelength converter with multi-channel broadcasting --- p.11 / Chapter 1.4. --- Overview --- p.12 / Chapter 2. --- PRINCIPLES AND THEORIES --- p.18 / Chapter 2.1. --- Optical nonlinearity --- p.19 / Chapter 2.2. --- Self-phase modulation (SPM) --- p.21 / Chapter 2.3. --- Cross-phase modulation (XPM) --- p.25 / Reference: --- p.28 / Chapter 3. --- EXTINCTION RATIO ENHANCEMENT AND WAVELENGTH CONVERSION USING CROSS-PHASE MODULATION IN A DISPERSION-SHIFTED FIBER --- p.29 / Chapter 3.1. --- Introduction --- p.30 / Chapter 3.2. --- Experimental details of extinction ratio enhancement --- p.31 / Chapter 3.3. --- Result and Discussions --- p.32 / Chapter 3.4. --- Conclusion --- p.36 / References: --- p.37 / Chapter 4. --- ALL-OPTICAL ASK TO DPSK FORMAT CONVERSION --- p.38 / Chapter 4.1. --- All Optical ASK to DPSK Format Conversion Using Cross-Phase Modulation in a Non-linear Fiber --- p.39 / Chapter 4.1.1. --- Introduction --- p.40 / Chapter 4.1.2. --- Experimental Details of ASK to DPSK format conversion by XPM in DSF --- p.42 / Chapter 4.1.3. --- Results and Discussion --- p.44 / Chapter 4.1.4. --- Experimental Details of ASK to DPSK format conversion by XPM in PCF --- p.47 / Chapter 4.1.5. --- Result and Discussion of XPM in PCF --- p.49 / Chapter 4.1.6. --- Comparison of DSF and PCF --- p.51 / References: --- p.54 / Chapter 4.2. --- All Optical ASK to ASK/DPSK Orthogonal Code Format Conversion Using Cross-Phase Modulation in a Dispersion-Shifted Fiber --- p.56 / Chapter 4.2.1. --- Introduction --- p.57 / Chapter 4.2.2. --- Experimental Details of ASK to ASK/DPSK format conversion --- p.58 / Chapter 4.2.3. --- Results and Discussion --- p.60 / Chapter 4.2.4. --- Conclusion --- p.63 / References: --- p.64 / Chapter 5. --- ALL-OPTICAL RZ TO NRZ FORMAT CONVERSION --- p.65 / Chapter 5.1. --- Introduction --- p.65 / Chapter 5.2. --- All-Optical RZ to NRZ Data Format Conversion Using Spectral Broadening Effect in a Dispersion-Shifted Fiber --- p.67 / Chapter 5.2.1. --- Principle of RZ-to-NRZ format conversion using SPM --- p.68 / Chapter 5.2.2. --- Experiment Details --- p.71 / Chapter 5.2.3. --- Results and Discussion --- p.72 / Chapter 5.2.4. --- Conclusion --- p.77 / Chapter 5.3. --- Spectral Filtering from a Cross-Phase Modulated Signal for RZ to NRZ Format and Wavelength Conversion --- p.78 / Chapter 5.3.1. --- Principle of RZ to NRZ format conversion by XPM --- p.79 / Chapter 5.3.2. --- Experiment --- p.81 / Chapter 5.3.3. --- Results and Discussion --- p.83 / Chapter 5.3.4. --- Conclusions --- p.87 / References: --- p.88 / Chapter 6. --- ALL-OPTICAL CLOCK COMPONENT EXTRACTION FROM NRZ DATA SIGNALS USING SELF-PHASE MODULATION IN A DISPERSION-SHIFTED FIBER --- p.90 / Chapter 6.1. --- Introduction --- p.91 / Chapter 6.2. --- Experimental Details --- p.92 / Chapter 6.3. --- Results and Discussion --- p.93 / Chapter 6.4. --- Conclusion --- p.96 / References: --- p.97 / Chapter 7. --- ALL-OPTICAL WAVELENGTH MULTICASTING USING SELF- PHASE MODULATION IN A NONLINEAR PHOTONIC CRYSTAL FIBER --- p.98 / Chapter 7.1. --- Introduction --- p.99 / Chapter 7.2. --- Simulation results --- p.100 / Chapter 7.3. --- Experimental Details --- p.103 / Chapter 7.4. --- Result and Discussion --- p.104 / Chapter 7.5. --- Conclusions --- p.109 / References: --- p.110 / Chapter 8. --- CONCLUSION AND FUTURE WORK --- p.111 / Chapter 8.1. --- Conclusion --- p.111 / Chapter 8.2. --- Possible Future Work --- p.114 / References: --- p.116 / APPENDIX --- p.117 / List of Publications --- p.117

Protein modification is an essential tool in Chemical Biology, allowing a functional biomolecule to be equipped with a small molecule tag or label. However, as proteins are constructed from a limited palette of around 20 canonical amino acids, achieving selective modification can be problematic. Previously reported methods for protein modification will be discussed in Chapter 1; these often rely on alteration of the protein sequence to introduce a uniquely reactive (often non-canonical) amino acid which may then be covalently modified in a bioorthogonal manner. An alternative approach is to identify a uniquely reactive site within the native protein sequence, such as the protein N-terminus or the reactive side chain of an amino acid with low frequency, and modify this using selective chemistry. In this project, modification of a native sequence protein was achieved by targeting a low abundance residue, tyrosine (Tyr), in a selective manner. Tyr was identified as the ideal candidate as it displays only ~3% frequency in the proteome and, due to its electron-rich aryl ring, it can be selectively modified by electrophilic aromatic substitution. Using a diazonium salt as the tuned electrophile, modification results in formation of an azobenzene motif which may be orthogonally cleaved under mild reducing conditions. The resulting cleavage product bears an o-aminophenol modification on the Tyr side chain, which can then be conjugated to a fluorescent label using established chemistry. This system has been developed on a solid-phase platform to give further control over the extent of modification achieved. In Chapter 2, the component parts of this method are developed through reactions performed in-solution on small molecule substrates. In Chapter 3, this work is then moved onto a solid-phase resin in order to 'catch-and-release' small molecule and peptide substrates. Finally in Chapter 4, the resin-based catch-and-release system is optimised for use in protein modification, and analysis of the modification site is explored.

The present thesis is examining the forced vibrations of a circular cylinder in the low Reynolds number flow of 200. A numerical study is performed that employs an already existing algorithm developed by (Breuer 1998) and enhanced with the characteristic of the cylinder's motion by (MadaniKermani 2014) who employed the moving frame of reference method of (L. Li, Sherwin et al. 2002). The algorithm was extensively assessed for the benchmark studies of flow around a stationary circular cylinder. A new observation was made on the effect of the aspect ratio of the computational cells in the mid region of the wake. The studies so far are emphasizing on the characteristic of a dense mesh, with a small aspect ratio, in the high divergence areas in the near region of the cylinder surface, neglecting the effect of the regions away from the surface. The present study on a stationary circular cylinder flow, proved that the aspect ratio of the distant cells has a significant effect on the St number and the force coefficients. The main study of the thesis emphasizes on the lock-in region where the wake oscillates in unison with the harmonic motion of the cylinder. The study makes a new observation on the qualitative and quantitative description of the lock-in conditions. In particular, it reveals two regions of resonance and non-resonance lock-in. Despite the fact that the lock-in is achieved, when the frequency ratio is in the first part of the region away from the unity ratio, the forces are not greatly magnified. As the ratio approaches the unity the forces experience a resonance that reaches the highest value after the unity. Furthermore, the adaptation time of the flow to the motion of the cylinder is examined and extends the results of (Anagnostopoulos 2000) to the full extent of the lock-in and the non-lock-in regions. More precisely the flow strives to reach a steady state when it is in the lock-in region rather in the non-lock in cases it reaches the steady state faster. It is postulated that the adaptation time depends on both the numerical and the physical adaptation. Moreover, the force coefficients characteristic of sinusoidal behaviour in the lock-in region is attempted to be approximated by a Newton polynomial that is built by making use of the divided differences method. The amplitude of the forces is approximated by a third degree Netwon polynomial built from the results of the present thesis simulations. The use of an approximation is providing faster results ignoring the need for a full resolution of the Navier-Stokes equation.

Yu Wei-jian. / Thesis submitted in: November 2000. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 70-71). / Text in English; abstracts in English and Chinese. / Yu Wei-jian. / TITLE PAGE --- p.i / THESIS COMMITTEE --- p.ii / ABSTRACT (English) --- p.iii / ABSTRACT (Chinese) --- p.iv / ACKNOWLEDGEMENTS --- p.v / TABLE OF CONTENTS --- p.vi / LIST OF FIGURES --- p.viii / LIST OF TABLES --- p.ix / Chapter CHAPTER 1 --- INTRUDUCTION --- p.1 / Chapter Section 1.1 --- Background of the BN System --- p.1 / Chapter 1.1.1 --- Desirable Properties of c-BN --- p.1 / Chapter 1.1.2 --- Phases in the BN System --- p.2 / Chapter 1.1.3 --- Phase Diagram of BN --- p.4 / Chapter 1.1.4 --- Synthesis Techniques for c-BN Films --- p.5 / Chapter 1.1.5 --- Characterization of BN Films --- p.6 / Chapter Section 1.2 --- Background of Theory --- p.7 / Chapter Section 1.3 --- Objectives --- p.9 / Chapter 1.3.1 --- Determination of Stable State of BN --- p.9 / Chapter 1.3.2 --- Phonon-dispersion Relations of BN --- p.9 / Chapter 1.3.3 --- "Phase (p, T) Diagram" --- p.10 / Chapter 1.3.4 --- Transformation Paths in Direct Compressions --- p.10 / Chapter Section 1.4 --- Roadmap --- p.11 / Chapter CHAPTER 2 --- METHODS --- p.12 / Chapter Section 2.1 --- Density Functional Theory (DFT) for E0 Calculation --- p.12 / Chapter Section 2.2 --- Direct Force-constant Method --- p.16 / Chapter Section 2.2 --- Quasi-harmonic Approximation --- p.26 / Chapter CHAPTER 3 --- RESULTS --- p.27 / Chapter Section 3.1 --- Stable State of BN --- p.27 / Chapter Section 3.2 --- Phonon-dispersion Relations --- p.29 / Chapter Section 3.3 --- "Phase (p, T) Diagram of BN" --- p.36 / Chapter Section 3.4 --- Transformation Paths via Direct Compression --- p.44 / Chapter 3.4.1 --- Direct Compression of h-BN and r-BN --- p.46 / Chapter 3.4.2 --- Direct Compression of t-BN --- p.50 / Chapter Section 3.5 --- Energy Barriers in the Transformation of h-BN to c-BN --- p.52 / Chapter CHAPTER 4 --- DISCUSSION --- p.58 / Chapter Section 4.1 --- Transition States in the Transformation of h-BN to c-BN --- p.58 / Chapter Section 4.2 --- Phonon-dispersion Relations --- p.60 / Chapter Section 4.3 --- Phase Diagrams --- p.62 / Chapter Section 4.4 --- Future Studies --- p.63 / Chapter 4.4.1 --- Cubic BN Films Formation --- p.63 / Chapter 4.4.1.1 --- Nanoarches Nucleation --- p.64 / Chapter 4.4.1.2 --- Growth: Interfaces Between h-BN {0001} and c-BN Planes --- p.64 / Chapter 4.4.2 --- Transformation Paths of w-BN to c-BN and h-BN to r-BN --- p.65 / Chapter CHAPTER 5 --- CONCLUSION --- p.66 / APPENDIX: Mechanistic Models in c-BN Films Formation --- p.67 / REFERENCES --- p.70

Thesis. 1976. Sc.D.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Microfiche copy available in Archives and Engineering. / Vita. / Bibliography: leaves 122-128. / Sc.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Vita. / Includes bibliographical references. / by Lawrence Maxwell Krauss. / Ph.D.

No description available.

Au-delà de son utilisation en géophysique ou en métrologie à grande échelle, la télémétrie laser des longues distances devrait trouver de nombreuses applications pour les missions spatiales. Les instruments d'observation par synthèse ouverture en vols en formation demandent que la géométrie de la constellation soit connue et contrôlée à bien mieux que la longueur d’onde de la fenêtre d’observation. Pour répondre à ces besoins, nous avons étudié un nouveau schéma de mesure qui combine une mesure interférométrique, réalisée sur un faisceau à deux modes et une mesure de temps de vols. Mon travail de thèse a porté sur la conception, mise en œuvre et la caractérisation de la mesure interférométrique. Pour qu'elles ne soient pas affectées par les dérives lentes de l'instrumentation microonde, les deux mesures de phase de longueur d’onde optique (1.55 µm) et de longueur d’onde synthétique (15 mm) sont extraites d'un même signal d’interférence à deux modes en utilisant une procédure de mesure dédiée : on réalise des mesures du signal d’interférence à trois valeurs de la fréquence optique de la source, calculées d'après le résultat de la mesure de temps de vol. Le télémètre met à profit les propriétés du signal d'interférence à deux modes et exploite la phase et l'amplitude du signal à 20 GHz de façon à éliminer les dérives de phase à long terme du signal microonde dans les chaînes de mesure. On peut en attendre, en moins de 0.1 s, une mesure de résolution et d'exactitude inférieures au nanomètre. Le montage expérimental a permis de montrer que le principe de mesure est correct. Sur la mesure d’un chemin optique dans l'air, nous avons obtenu une résolution de 100 pm à 100 µs, qui nous permet d'observer le bruit acoustique. Le bruit sur la mesure des signaux permet d'espérer une résolution de à 10 pm à 43 ms. Les imperfections optiques du montage ont été mises en évidence: elles ont été décrites par une expression analytique, puis à l’aide d’optiques dédiées réduites au niveau nécessaire pour le fonctionnement de l'instrument. La phase des signaux de battement à 20 GHz est affectée d'erreurs de plusieurs 10-3 cycles qui, si elles ne sont pas corrigées, provoquent des erreurs de la mesure de longueur par une ou plusieurs fois la longueur d'onde optique. Nous avons réalisé une étude spécifique du couplage amplitude-phase à l'origine de cette déformation, et montré qu'il est en partie d'origine thermique, lié à la puissance de plusieurs kW/cm² dissipée dans les photodiodes à 20 GHz. Cet effet, voisin de ce qui est connu depuis quelques années en instrumentation microonde sous le nom d' "effet mémoire", est difficile à prendre en compte et la correction qui est faite sur les données ne parvient pas totalement à éviter que le télémètre délivre des valeurs erronées de la distance. En conclusion de ce mémoire deux options sont présentées afin de remédier à cette déformation du signal et d'aboutir à un instrument de haute exactitude. / Beyond its use in geophysics or in large scale metrology, laser-based measurement of long distances is expected to find numerous applications in space missions. Synthetic aperture instruments in formation flight require that the constellation geometry be known and controlled to much better than the wavelength of the observation window. To meet these needs, we have been studying a novel laser ranging scheme that combine an interferometric measurement, performed on a two-mode laser beam, and a time of flight measurement. My thesis focused on the design, implementation, and characterization of the interferometric measurement. To prevent systematic errors due to slow drifts in the microwave components, the two phase measurements of optical wavelength (1.55 microns) and the synthetic wavelength (15 mm) are extracted from the same two-mode interference signal by using a dedicated measurement procedure: we perform interference signal measurements at three optical frequency values of the laser source, calculated based on the time of flight measurement result. The rangefinder utilizes the two-mode interference signal properties and exploits phase and amplitude of the 20 GHz signal in a manner to eliminate long-term phase drifts of the microwave signal in the measurement chain. We can expect in less than 0.1 s, a measurement with sub-nanometer accuracy and resolution. The experimental setup showed that the principle is correct. On an optical path measurement in air, we obtained a 100 pm resolution in 100 us, which allows us to observe the acoustic noise. The measurement signal noise allows expecting a 10 pm resolution in 43 ms. Optical imperfections in the setup have been observed. They were described by an analytical expression, then, using dedicated optics, they were reduced to the level required for the instrument operation. The phase of two-mode signal is affected to several 10-3 cycle errors which, if not corrected, result in errors in the measurement length by multiples of the optical wavelength. We performed a specific study of amplitude-to-phase coupling causing this deformation, and showed that it is part of thermal origin, related to the power of several kW/cm² dissipated in the 20 GHz photodiodes. This effect, close to what has been known for some years in microwave instrumentation under the name of "memory effects", is difficult to take into account and the correction made on the data can not completely prevent the rangefinder from delivering incorrect values of the distance. In concluding this thesis two options are presented to remedy this signal distortion and result in a high accuracy instrument.