Lau Chun Keung = 受調諧下溫度湍流的實驗研究 / 劉振強. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 86-88). / Text in English; abstracts in English and Chinese. / Lau Chun Keung = Shou diao xie xia wen du tuan liu de shi yan yan jiu / Liu Zhenqiang. / Chapter 1 --- Acknowledgments --- p.iii / Chapter 2 --- Introduction --- p.1 / Chapter 2.1 --- Pulsating flow --- p.1 / Chapter 2.2 --- Rayleigh Bernard Convection: Equations and Parameters --- p.5 / Chapter 2.3 --- Rayleigh Benard Convection: Physical Picture --- p.7 / Chapter 2.4 --- Previous work on Turbulent Convection --- p.10 / Chapter 2.5 --- Motivation --- p.11 / Chapter 3 --- Experimental Setup --- p.13 / Chapter 3.1 --- The Convection cell --- p.13 / Chapter 3.2 --- Heating and Cooling --- p.18 / Chapter 3.3 --- Temperature and Voltage measurement --- p.20 / Chapter 3.3.1 --- Temperature Probes --- p.20 / Chapter 3.3.2 --- "Data, acquisition: Multimeters and Lock-In" --- p.22 / Chapter 4 --- Experimental Results --- p.27 / Chapter 4.1 --- Steady State Convection --- p.27 / Chapter 4.1.1 --- Experimental parameters and its determination --- p.27 / Chapter 4.1.2 --- Fluctuations at various locat ion of cell --- p.28 / Chapter 4.1.3 --- Nusselt Number --- p.37 / Chapter 4.2 --- Modulated Convection --- p.38 / Chapter 4.2.1 --- Parameters of the system --- p.40 / Chapter 4.2.2 --- Temperature variation at the plates: general picture --- p.41 / Chapter 4.2.3 --- Temperature variation at the plates: modulatiou frequency dependence --- p.42 / Chapter 4.2.4 --- Phase differences between response and modulation --- p.58 / Chapter 4.2.5 --- Temperature Variation at the Plates: Further Exploration of Parameter Space --- p.61 / Chapter 4.2.6 --- Local Signals at Mid-Height under modulation --- p.63 / Chapter 4.2.7 --- Time lag between two probes --- p.76 / Chapter 5 --- Conclusion --- p.83 / Chapter 5.1 --- Conclusion --- p.83 / Chapter 5.2 --- Outlook for further studies --- p.85 / Bibliography --- p.86 / Thermal dissipation rate --- p.89

Zhou Sheng-qi = 高瑞利數湍流熱對流中溫度和速度場的結構和統計性質研究 / 周生启. / "December 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 134-147) / 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. / Zhou Sheng-qi = Gaoruili shu tuan liu re dui liu zhong wen du he su du chang de jie gou he tong ji xing zhi yan jiu / Zhou Shengqi.

by Lui Siu Lung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 132-136). / by Lui Siu Lung. / Abstract --- p.i / Acknowledgements --- p.ii / Table of Contents --- p.iii / List of Figures --- p.v / Chapter / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- The Parameters --- p.1 / Chapter 1.2 --- The Stories of Turbulent Convection --- p.2 / Chapter 1.3 --- The Models: Plumes with no Flow or a Flow with no Plumes? --- p.3 / Chapter 1.4 --- Building up the Picture --- p.5 / Chapter 1.5 --- Starting Point of the Experiment --- p.6 / Chapter 2. --- Setup of the Experimental Environment --- p.8 / Chapter 2.1 --- The Convection Cell --- p.8 / Chapter 2.2 --- The Temperature Probe --- p.12 / Chapter 2.3 --- The Thermistors --- p.15 / Chapter 2.4 --- The Large Scale Circulation and the Plumes --- p.19 / Chapter 2.5 --- Building up the Convection --- p.22 / Chapter 3. --- Hard Turbulence Properties and Scalings in the Normal Cell --- p.27 / Chapter 3.1 --- Heat Transfer Efficiency --- p.27 / Chapter 3.2 --- Thermal Boundary Layer --- p.32 / Chapter 3.3 --- The RMS Temperature Fluctuation --- p.39 / Chapter 3.4 --- Temperature Time Series --- p.42 / Chapter 3.5 --- Histograms --- p.48 / Chapter 3.6 --- Power Spectrum --- p.53 / Chapter 3.7 --- Summary on the Normal Cell --- p.56 / Chapter 4. --- Horizontal-Position-Dependent Thermal Boundary Layer --- p.58 / Chapter 4.1 --- Orientation --- p.59 / Chapter 4.2 --- Along the Large Scale Circulation --- p.60 / Chapter 4.3 --- Perpendicular to the Large Scale Circulation --- p.70 / Chapter 4.4 --- Horizontal Measurement for the A = 2 Cell --- p.78 / Chapter 4.5 --- Summary on the Horizontal Measurement --- p.81 / Chapter 5. --- Sphere in the Cell --- p.84 / Chapter 5.1 --- Heat Transfer Efficiency --- p.84 / Chapter 5.2 --- Thermal Boundary Layer --- p.86 / Chapter 5.3 --- The RMS Temperature Fluctuation --- p.87 / Chapter 5.4 --- Temperature Time Series --- p.88 / Chapter 5.5 --- Histograms --- p.92 / Chapter 5.6 --- Summary on the Sphere Cell --- p.94 / Chapter 6. --- Fingers in the Cell --- p.96 / Chapter 6.1 --- The Gear Cell --- p.96 / Chapter 6.1.1 --- Heat Transfer Efficiency --- p.96 / Chapter 6.1.2 --- Thermal Boundary Layer --- p.98 / Chapter 6.1.3 --- Flow Pattern in the Gear Cell --- p.100 / Chapter 6.1.4 --- Temperature Time Series --- p.104 / Chapter 6.1.5 --- Histograms --- p.109 / Chapter 6.1.6 --- Power Spectrum --- p.110 / Chapter 6.2 --- The Finger Cell --- p.117 / Chapter 6.2.1 --- Heat Transfer Efficiency --- p.117 / Chapter 6.2.2 --- Temperature Time Series --- p.120 / Chapter 6.2.3 --- Histograms --- p.122 / Chapter 6.2.4 --- Power Spectrum --- p.125 / Chapter 6.3 --- Summary on the Finger Cells --- p.127 / Chapter 7. --- Conclusions --- p.129 / References --- p.132 / Appendix --- p.137

Thesis--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution. / Includes bibliographical references (leaves 220-233).

Rayleigh-Bénard convection has been extensively studied in literature owing to its ubiquitous nature. However, most of the studies have been confined to geometries where the aspect ratio of the cylinder was less than 1. Here we study the motion of fluid in geometries with aspect ratio greater than 1, with particular application to use of such motion to actuate biochemical reactions, such as the polymerase chain reaction. We show that it is possible to accelerate the rate of reaction by using a geometry that promotes chaotic motion versus a geometry that promotes quasi- periodic motion. We also simulate chemical kinetics using the fluid motion as a starting point and we prove that chaotic motion indeed enhances the rate of the reaction. We also provide qualitative and quantitative measures for chaotic motion in a fluid flow, which helps to distinguish between different types of fluid motion. We highlight the transitions between different types of flow that are possible with Rayleigh-Bénard convection. Finally, we compare our simulations against experimental data obtained from particle image velocimetry, laser induced fluorescence and optical microscopic visualization.

In mobile radio systems, the bandwidth of spread spectrum signals for CDMA system is very wide. If the bandwidth exceeds the coherence bandwidth of the channel, the signal is transmitted in the frequency-selective channel, and the signal is severely distorted by the multiple propagation paths. Each bandwidth of the signals for Multi-Carrier CDMA system is smaller. If the bandwidth is smaller than the coherence bandwidth of the channel, the channel is said to be frequency-nonselective. Besides, the data rate of Multi-carrier-CDMA is higher than the data rate of CDMA. If the traditional combing detector is used for Multi-Carrier CDMA system, the channel coefficients have to be estimated first. The error of the estimated channel coefficients will result in the performance of detector degrade. The blind adaptive algorithm doesn

Gas bearings enable successful applications in high speed oil-free microturbomachinery. This thesis presents analysis and experiments of the dynamic performance of a rotor supported on Rayleigh step gas bearings. Comprehensive experiments demonstrate that Rayleigh step hybrid gas bearings exhibit adequate stiffness and damping capability in a narrow range of shaft speeds, up to ~ 20 krpm. Rotor coastdown responses were performed for two test bearing sets with nominal radial clearance of 25.4 ?m and 38.1 ?m, respectively. A near-frictionless carbon (NFC) coating was applied on the rotor to reduce friction against its bearings at liftoff and touchdown. However, the rotor still experienced dry friction at low shaft speeds (below ~ 4,000 rpm). Experiments show that the supply pressure raises the rotor critical speed and decreases the system damping ratio. The geometry of the Rayleigh steps distributed on the rotor surface generates a time varying pressure field and results in a sizable 4X super synchronous component of bearing transmitted load. The external supply gas pressure affects slightly the onset speed of instability of the rotor-bearing system. The unstable whirl frequencies are nearly fixed at the system natural frequency (~ 120 Hz). Analysis with a finite element model predicts the stiffness and damping force coefficients for the bearing accounting for a purely hydrodynamic operation condition. Predictions show the synchronous stiffness and damping coefficients decrease with shaft speed. Predicted threshold speeds of instability are lower, ~ 50% or less than the measurement due to the analytical model limitations assuming a grooved stator. The predicted synchronous responses to imbalance correlate well with the measurements, however. The Rayleigh step gas bearing shows similar characteristics to the flexure pivot tilting pad bearing (FPTPB) tested in 2003. However, the test Rayleigh step gas bearings exhibit a much reduced stable operating speed range, below 20 krpm. The maximum speed achieved is much lower to that determined with an identical rotor supported on FPTPBs, i.e. rotor dynamically stable up to 100 krpm. The FPTPB is more reliable in high speed oil-free applications due to its excellent stability characteristics.

Experiments and direct numerical simulations (DNS) have been performed to examine the e¤ects of initial conditions on the dynamics of a Rayleigh-Taylor unsta- ble mixing layer. Experiments were performed on a water channel facility to measure the interfacial and velocity perturbations initially present at the two-fluid interface in a small Atwood number mixing layer. The experimental measurements have been parameterized for use in numerical simulations of the experiment. Two- and three- dimensional DNS of the experiment have been performed using the parameterized initial conditions. It is shown that simulations implemented with initial velocity and density perturbations, rather than density perturbations alone, are required to match experimentally-measured statistics and spectra. Data acquired from both the exper- iment and numerical simulations are used to examine the role of initial conditions on the evolution of integral-scale, turbulence, and mixing statistics. Early-time turbu- lence and mixing statistics are shown to be strongly-dependent upon the early-time transition of the initial perturbation from a weakly-nonlinear to a strongly-nonlinear flow.

Optical fiber access technology is the key to realize a broadband communication for everyone, and the passive optical network (PON) is enabling customers to enjoy high-speed internet access now. As the demand for the broadband access is still growing, a study to find out technologies to realize wider bandwidth for the access system is quite important. At this moment, wavelength division multiplexing (WDM) PON is the most promising technology for the future optical fiber access system. Current PON system covers a reach of within 20km from a central office, because the market of the access system is focusing on well-populated area. It is required to extend the reach of the PON system to enhance the applicable area, because there are many regions in the world where are not so highly populated. Therefore, this master thesis is focusing on to enhance the reach of the WDM-PON system. A little more specifically, a single fiber bidirectional 80 km WDM PON system with symmetric up-and-downstream data rate of 10.66Gb/s is reported. In order to enhance the reach of the WDM-PON system, Raman amplifier is utilized. As the Raman amplifier can amplify both directional optical signals simultaneously, it is quite effective to enhance the reach of the WDM-PON system. Even though, there are several effects that cause performance degradations of the system by introducing the Raman amplifier. It is important to clarify such effects and to provide solutions. This thesis discusses these issues also. One factor to degrade the system performance is the Rayleigh backscattering. As the Raman amplifier amplifies the Rayleigh backscattering, it interferes to the signal and causes the crosstalk penalty. At first, an experimental study has been conducted to clarify the significance of the Rayleigh backscattering, and the method to overcome the crosstalk penalty is presented. Then, another experiment to realize 80km WDM PON system with Raman amplifier is conducted, and it demonstrates a feasibility of such system. Finally, this thesis is concluded by a successful demonstration of the WDM-PON system with an enhanced reach.

Thesis (M.S.)--Missouri University of Science and Technology, 2009. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 25, 2009) Includes bibliographical references (p. 23-24).