Wong Wai Kin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 195-200). / Wong Wai Kin. / Acknowledgements --- p.i / Abstract --- p.ii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Kelvin features in easterly surges in southern China --- p.5 / Chapter 1.2 --- Northerly surges in southern China --- p.7 / Chapter 1.3 --- Objectives and Methodology --- p.8 / Chapter 2 --- Theory of Kelvin Waves against an Incline --- p.9 / Chapter 2.1 --- Introduction --- p.9 / Chapter 2.2 --- General formalism --- p.13 / Chapter 2.3 --- Vertical barrier --- p.17 / Chapter 2 4 --- Infinite incline --- p.18 / Chapter 2.5 --- Finite incline --- p.21 / Chapter 2.6 --- Analysis of scales and non-dimensional variables --- p.24 / Chapter 2.7 --- The governing equation of pressure disturbance --- p.30 / Chapter 2.7.1 --- Variational Principle --- p.31 / Chapter 2.7.2 --- Integration of continuity equation --- p.32 / Chapter 2 8 --- Kelvin waves against a topography --- p.33 / Chapter 2.9 --- Summary --- p.37 / Chapter 3 --- Numerical Study of Linear Kelvin Waves --- p.39 / Chapter 3.1 --- Introduction --- p.39 / Chapter 3.2 --- Shallow Water Wave Theory --- p.40 / Chapter 3.3 --- Kelvin wave in the presence of topography --- p.43 / Chapter 3.4 --- Numerical model --- p.47 / Chapter 3.5 --- Uniform or slowly varying topography depth --- p.50 / Chapter 3.5.1 --- Uniform topographical depth --- p.51 / Chapter 3.5.2 --- Slowly varying bottom topography --- p.52 / Chapter 3.6 --- Numerical study on infinite incline --- p.54 / Chapter 3.7 --- Finite incline --- p.57 / Chapter 3.8 --- Numerical experiments using more realistic terrain --- p.61 / Chapter 3.8.1 --- Experiment A --- p.61 / Chapter 3.8.2 --- Experiment --- p.64 / Chapter 3.9 --- Further discussion --- p.69 / Chapter 3.10 --- Coastal Kelvin waves features of northeasterly cold surges in Southern China --- p.74 / Chapter 3.11 --- Summary --- p.75 / Chapter 4 --- Nonlinear Kelvin Waves Features --- p.78 / Chapter 4.1 --- Introduction --- p.78 / Chapter 4.2 --- Mathematical Model --- p.82 / Chapter 4.3 --- Existence of Non-linear Travelling Solution --- p.85 / Chapter 4.4 --- Qualitative discussion on solution --- p.86 / Chapter 4.4.1 --- Linearized equation at Z = 0 --- p.87 / Chapter 4.4.2 --- Linearized equations at Z1 --- p.88 / Chapter 4.4.3 --- Case with no viscosity --- p.88 / Chapter 4.4.4 --- Case with viscosity: m2 > m2 > 0 --- p.92 / Chapter 4.4.5 --- Case with viscosity: m2 > m2 > 0 --- p.94 / Chapter 4.5 --- Expression for the wave speed --- p.95 / Chapter 4.5.1 --- Solitary Wave --- p.96 / Chapter 4.5.2 --- Travelling Wave --- p.96 / Chapter 4.6 --- Numerical Calculations --- p.98 / Chapter 4.6.1 --- Shooting method --- p.98 / Chapter 4.6.2 --- Nonlinear Periodic Solution --- p.100 / Chapter 4.6.3 --- Nonlinear Solitary Wave Solution --- p.100 / Chapter 4.6.4 --- Oscillatory Travelling Wave Solution --- p.102 / Chapter 4.6.5 --- Monotonic Travelling Wave Solution --- p.104 / Chapter 4.7 --- Wave Disturbance along y direction --- p.107 / Chapter 4 8 --- Existence of the terrain gradient --- p.109 / Chapter 4.9 --- Summary --- p.116 / Chapter 5 --- Froude Number Study on Northerly Cold surges --- p.118 / Chapter 5.1 --- Introduction --- p.118 / Chapter 5.1.1 --- Prediction of cold surges passing over the NanLing Range --- p.118 / Chapter 5.1.2 --- Theoretical studies on orographic blocking effect and the Froude number --- p.119 / Chapter 5.2 --- Methodology --- p.123 / Chapter 5.2.1 --- Physical meaning of the Froude number --- p.123 / Chapter 5.2.2 --- Definition of northerly cold surges --- p.125 / Chapter 5.2.3 --- Method of calculation using ECMWF data set --- p.126 / Chapter 5 .2. --- 4 Calculation using the meteorological station data --- p.127 / Chapter 5.3 --- Result --- p.127 / Chapter 5.3.1 --- Froude Number Statistics using ECMWF data --- p.127 / Chapter 5.3.2 --- Froude number statistics using meteorological station data --- p.133 / Chapter 5.4 --- Non-dimensional number statistics combining rotation and stratification --- p.135 / Chapter 5.5 --- Summary --- p.138 / Chapter 6 --- Diagnostic Study on Northerly Cold Surge --- p.140 / Chapter 6.1 --- Introduction --- p.140 / Chapter 6. 2 --- Diagnostic variables in the study --- p.141 / Chapter 6.2.1 --- Diagnosis of geopotential tendency in terms of advection of relative vorticity --- p.142 / Chapter 6.2.2 --- Diagnosis of the vertical motion --- p.144 / Chapter 6.3 --- Data and calculation --- p.147 / Chapter 6.4 --- Results and Discussion --- p.149 / Chapter 6. 4 --- .1 Brief description on the cold surge --- p.149 / Chapter 6.4.2 --- Diagnosis using ECMWF data set --- p.149 / Chapter 6.4.3 --- Diagnosis using the limited area model simulation results --- p.161 / Chapter 6.5 --- Summary --- p.162 / Chapter 7 --- Conclusion --- p.169 / Appendices --- p.172 / Chapter A --- Non-dimensional Governing Equations --- p.172 / Chapter B --- Governing Equation for Pressure Disturbance --- p.177 / Chapter B.1 --- Variation Approach --- p.177 / Chapter B.2 --- Integration of Continuity Equation --- p.180 / Chapter C --- "Semigeostrophic Theory, Dispersion and Dissipation" --- p.182 / Chapter C.1 --- Semigeostrophic Approximation --- p.182 / Chapter C.2 --- Dispersive effects --- p.188 / Chapter C.3 --- Dissipative effects --- p.190 / Chapter D --- Bibliography

An expansive repertoire of original chamber works is available for ensembles comprised of saxophone, wind and percussion instruments. Many musicians, including saxophonists and conductors, are unaware of this enormous body of literature. This produces a compelling need for sources of identification available to conductors, performers and teachers. This study begins to provide such a source through the presentation of selected works and the accompanying annotated bibliography. The lack of awareness of available scores for chamber music with saxophone, winds and percussion among conductors and many performers often contributes to the absence of these works in concert halls. The objective of this lecture-recital document is to make available a tool that includes only original works for the saxophone in a variety of chamber ensemble settings. The nature of this study will be descriptive. The literature chosen for this project reveals varying levels of performance difficulty, compositional techniques, form, and instrumentation. Chosen works employ an ensemble size that requires a conductor or are more successfully performed with a conductor. Selected compositions are illustrated in which the saxophone is identified as a vital ingredient in an already existing repertoire of serious chamber literature. Works in this study include original compositions using from seven to seventeen musicians. Some of the works discussed in this study include double bass and piano. Chapters include information on the Parameters of Study (Introduction, Historical Perspective, Sources, Criteria, Selection of Works for Analysis), composer Jean Françaix, a Historical Overview and Detailed Study of Danses Exotiques, composer Fisher Tull, a Historical Overview and Detailed Study of Nonet and an Annotated Bibliography of compositions matching the established criteria. Appendices include List of Works of Fisher Tull and Jean Françaix.

Wong Ho Man, William. / "Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 2002-2003, design report." / Chapter 1 --- Introduction --- p.P.02 / Chapter 2 --- Project Vision --- p.P.03 / Chapter 3 --- Project Objectives --- p.P.04 / Chapter 4 --- Research Plan and Methodology --- p.P.05 / Chapter 5 --- Developed Wind Phenomenons --- p.P.07 / Chapter 6 --- Investigation Process and Findings --- p.P.17 / Chapter 7 --- Design Development --- p.P.24 / Chapter 8 --- Final Design --- p.P.33 / Chapter 9 --- Conclusion --- p.P.41

Coastal South African cities like Port Elizabeth are said to have a strong potential for wind energy. This study aims to model wind data in order to be able assess the power potential belonging to a given site. The main challenge in modelling wind direction data is that it is categorized as circular data and therefore requires special techniques for handling that are different from usual statistical samples. Statistical tools such as descriptive measures and distribution fitting, were re-invented for directional data by researchers in this field. The von Mises distribution is a predominant distribution in circular statistics and is commonly used to describe wind directions. In this study, the circular principles described by previous researchers were developed by using the statistical software, Mathematica. Graphical methods to present the wind data were developed to give an overview of the behaviour of the winds in any given area. Data collected at Coega, an area near Port Elizabeth, South Africa, was used to illustrate the models which were established in this study. Circular distributions were fit to the directional data in order to make appropriate conclusions about the prevailing wind directions in this area.

Coastal South African cities like Port Elizabeth are said to have a strong potential for wind energy. This study aims to model wind data in order to be able assess the power potential belonging to a given site. The main challenge in modelling wind direction data is that it is categorized as circular data and therefore requires special techniques for handling that are different from usual statistical samples. Statistical tools such as descriptive measures and distribution fitting, were re-invented for directional data by researchers in this field. The von Mises distribution is a predominant distribution in circular statistics and is commonly used to describe wind directions. In this study, the circular principles described by previous researchers were developed by using the statistical software, Mathematica. Graphical methods to present the wind data were developed to give an overview of the behaviour of the winds in any given area. Data collected at Coega, an area near Port Elizabeth, South Africa, was used to illustrate the models which were established in this study. Circular distributions were fit to the directional data in order to make appropriate conclusions about the prevailing wind directions in this area.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Meteorology and Physical Oceanography, 1981. / Microfiche copy available in Archives and Science. / Bibliography: leaves 53-54. / by James Che-Ming Chung. / M.S.

Equatorial plasma bubbles (EPBs) are large structures consisting of depleted plasma that generally form on the nightside of Earth's ionosphere along magnetic field lines in the upper thermosphere/ionosphere. While referred to as `bubbles', EPBs tend to be longer along magnetic latitudes and narrower along magnetic longitudes which are on the order of thousands and hundreds of kilometers, respectively. EPBs are a well documented occurrence with observations spanning many decades. As such, much is known about their general behavior, seasonal variation of occurrences, increasing/decreasing occurrences with increasing/decreasing solar activity, and their ability to interact and interfere with radio waves such as GPS. This dissertation expands on this understanding by focusing on the detection and tracking of EPBs in the upper thermosphere/ionosphere along equatorial to low latitudes. To do this, far ultraviolet (FUV) emission observations of the recombination of O$^+$ with electrons via the Global-Scale Observations of the Limb and Disk (GOLD) mission are analyzed. GOLD provides consistent data from geostationary orbit with the eastern region of the Americas, Atlantic, and western Africa. The optical data can be used to pick out gradients in brightness along the 135.6 nm wavelength which correlate with the location of EPBs in the nightside ionosphere. The dissertation provides a novel method to look at and analyze 2-dimensional data with inconsistent time-steps for EPB detection and tracking. During development, preprocessing of large scale (multiple years) data proved to be the largest time sync. To that end, this dissertation tests the possibility of using convolution neural networks for detection of EPBs with the end goal of reducing the amount of preprocessing necessary. Further, data from the Ionospheric Connection Explorer's (ICON's) ion velocity meter (IVM) are compared to EPBs detected via GOLD to understand how the ambient plasma around the EPBs behave. Along with the ambient plasma, zonal and meridional thermospheric winds observed by ICON's Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument are analyzed in conjunction with the same EPBs to understand how winds coincident with EPBs behave. An analysis of winds before EPBs form is also done to observe the potential for both zonal and meridional winds' ability to suppress and amplify EPB formation. / Doctor of Philosophy / Equatorial plasma bubbles (EPBs) are large structures that generally form during post- sunset along Earth's magnetic equator. While referred to as `bubbles', EPBs tend to be thousands of kilometers from north to south and hundreds of kilometers from east to west and well over a thousands kilometers in altitude. EPBs are a well documented occurrence with observations spanning many decades. This includes their ability to interfere with radar and GPS. This dissertation expands on the scientific community's understanding by focusing on the detection and tracking of EPBs along the magnetic equator. To do this, observations from the NASA Global-Scale Observations of the Limb and Disk (GOLD) mission are analyzed. GOLD provides consistent observations looking over the eastern region of the Americas, Atlantic, and western Africa. A unique method to look at and analyze this data for EPB detection and tracking is developed. This dissertation also tests the possibility of using machine learning for detection of EPBs. Further, data from the NASA Ionospheric Connection Explorer (ICON) mission is compared to EPBs detected via GOLD to understand how the behavior of the upper atmosphere and the conductive region therein, known as the ionosphere, interact with the EBPs themselves.

Thesis (PhD (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 1992. / The effect of cross-winds on the performance of natural draft dry-cooling towers is studied by means of isothermal model tests, a numerical simulation and full scale measurements. The action of the wind on such towers is found to be complex and is influenced by a number of different parameters including the wind speed, the shape of the approaching wind profile, the inlet diameter to the inlet height ratio of the tower, the tower height, the shape of the tower shell, the pressure loss coefficient of the heat exchangers and the amount of heat rejected by the tower. For a horizontal arrangement of the heat exchangers the wind effect on the tower is shown to be strongly dependent on both the shape and pressure loss coefficient of the tower supports. In practical cooling towers the heat exchangers are either arranged horizontally in the inlet cross-section of the tower or vertically around the circumference of the tower and the wind effect is found to be dependent on the particular layout. The wind effect on a tower is furthermore found to increase if the heat exchangers are arranged in the form of A-frames. Additional reductions in the heat rejection rate of the tower are caused by a non-uniform air temperature distribution inside the tower and flow distortions through the heat exchanger. Significant reductions in the wind effect on a cooling tower can be achieved by installing windbreak walls below the heat exchangers if the latter are arranged horizontally in the tower inlet.

Thesis (PhD)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT:This work is concerned with the numerical simulation of the aeolian snow transportation process (drifting or wind blown snow) and especially the snow deposition and erosion phenomenon (snow drift). The research work is interested in modelling the atmospheric boundary layer wind flow and its associated snow drifting processes around threedimensional obstacles by means of computational fluid dynamics (CFD). A modelling method is required to predict and evaluate the snow drifting phenomenon surrounding the SANAE IV research station in Antarctica. This station is of an elevated design to ensure that wind blown snow may travel around the structure relatively undisturbed and without deposition near the structure. This design is partly successful but localised drifts are formed especially leeward of the interconnecting structures that join the main building sections together. The theoretical and numerical description to describe the turbulent transport of the two-phase mixture of air and snow particles is investigated. This theory is subsequently employed to describe the snow deposition and erosion process and two models are developed to determine the deposition flux onto the snow surface. These models presented and discussed are a threshold based approach and a conservative based approach. The first model is dependent on a threshold shear velocity to determine the onset of either erosion or deposition. The second model determines the deposition or erosion flux based on the conservation of the snow mass transport in the near surface control volume. A numerical scheme that evaluates the snow deposition flux at the surface and forces a temporal surface adaptation during the simulation is established and implemented in a commercial CFD software code by means of user subroutines. Various test cases for which observed snow drift data are available are numerically modelled to validate the snow drift schemes presented in this work. These tests include the wind driven snow accumulation around a three-dimensional cube, around two adjacent three-dimensional cubes and near a typical porous snow fence. The results indicate that both methods can predict realistic snow drifts for a variety of wind flow conditions but also show that the conservative approach is superior to the threshold based approach in describing the snow drift process around obstacles. This model allows drifts to form not only in areas of low flow velocities but also under high shear conditions. The theoretical investigation and the development and validation of the conservatively based snow drift scheme shows that drift formation depends strongly on the near surface flow divergence and secondary flow structures. To resolve the snow drift formation under a variety of flow conditions a three-dimensional field solution is required to determine velocity and snow concentration gradients and include the effects of near surface convective and turbulent entrainment. The model is applied to numerically simulate and predict snow drifting around the SANAE IV base for a moderate as well as a high wind speed event. The predicted snow drift around the base agrees favourably with the observed drifts at the station. Further numerical simulations are carried out to evaluate the effects a few design modifications may have on the snow deposition. These results suggest that a simple baffle plate installation near the bottom of the interconnecting link structures may minimise the snow accumulation leeward of that area. This study shows that to achieve realistic numerical snow drift predictions around, on or near obstacles, a conservative based snow drift scheme should be considered using some form of temporal terrain adaptation strategy. Only then does one include a sufficient level of important flow effects such as deposition along near surface boundaries of strong flow divergence which plays as an important role as vertical settling and entrainment in determining deposition rates. / AFRIKAANSE OPSOMMING:Hierdie studie behels die numeriese simulasie van windgedrewe sneeubeweging asook die daarmee gepaardgaande sneeu neerslag en erosie eienskappe. Die navorsing het verder belang in die berekening van die atmosferiese grenslaag vloei en die simulasie van sneeu neerslag naby drie-dimensionele strukture deur gebruik te maak van berekeningsvloeimeganika (BVM). ‘n Berekeningsmetodiek is nodig om die eienskappe van die sneeu neerslag rondom die SANAE IV navorsingsstasie in Antarktika te voorspel en te evalueer. Die bogrondse struktuur is spesifiek so ontwerp om te verseker dat wind gedrewe sneeu hoofsaaklik onversteurd verby die struktuur kan beweeg sonder neerslag teenaan die struktuur. Die ontwerp is grotendeels suksesvol alhoewel sneeu neerslag wel lokaal plaasvind, wind af vanaf die aansluitings strukture tussen die hoof geboue. Die teoretiese en numeriese beskrywing van die twee-fase lug- en sneeumengsel beweging word ondersoek en gebruik om die sneeu neerslag en erosie einskappe te beskryf. Twee modelle wat hierdie verskynsel beskryf word beskryf en bespreek naamlik ‘n drumpel gebaseerde benadering en ‘n konserwatief gebaseerde benadering. Die eerste model is afhanklik van ‘n drumpel skuifsnelheid om die aanvang van of erosie of neerslag te bereken. Die tweede model bereken die neerslag eerder gebaseer op die behoud van die sneeu massa vloei in die kontrole volume naby aan die oppervlak. ‘n Numeriese metode is ontwikkel en geimplementeer in ‘n kommersiële BVM sagteware pakket deur van gebruikerssubroetines gebruik te maak. Die ontwikkelde kode evalueer die sneeu neerslag vloed by die oppervlak en forseer ‘n tydafhanklike oppervlak aanpassing gedurende die simulasie. Die sneeu neerslag metode wat beskryf word in hierdie studie word ge-evalueer teen verskeie toetsgevalle waarvoor daar waargenome sneeu neerslag resultate beskikbaar is. Hierdie toetse sluit in die wind gedrewe sneeu neerslag rondom ‘n drie-dimensionele kubus, rondom twee naby geleë kubusse en naby ‘n tipiese poruese sneeu heining. Die resultate dui aan dat beide die metodes realistiese sneeu neerslag voorspel vir verskeie wind toestande. Die studie wys ook dat die konserwatief gebaseerde benadering vir die beskrywing van die sneeu neerslag proses meer akkuraat is as die drumpel gebaseerde benadering aangesien die neerslagvoorspel kan word nie net alleenlik in gebiede met lae vloeisnelhede nie, maar ook in gebiede waar hoë skuifsnelhede teenwoordig is. Die teoretiese ondersoek, ontwikkeling en toepassing van die konserwatief gebaseerde model dui daarop dat die neerslag afhanklik is van die divergensie van die vloeiveld asook van die sekondêre vloei patrone naby die oppervlak. Ten einde die sneeu neerslag vir verskeie toestande op te los is dit nodig om snelheids- en sneeukonsentrasie gradiënte te kan bereken in ‘n drie-dimensionele vloei veld om sodoende die invloed van naby-oppervlak konveksie en turbulente verspreiding in ag te neem. Die metode word toegepas deur die sneeu neerslag rondom die SANAE IV navorsingsstasie te voorspel vir ‘n gematigde asook ‘n hoë wind snelheid toestand. Die sneeu neerslag voorspelling stem gunstig ooreen met die waargenome neerslag by die struktuur. Verdere numeriese simulasies is uitgevoer om die invloed van ontwerpsverandering op die neerslag te evalueer. Uit hierdie resultate blyk dit dat ‘n eenvoudige plaat struktuur onder die aansluitingsstrukture die sneeu neerslag wind af mag verminder. Hierdie navorsingsstudie dui daarop dat ‘n tydafhanklike terrein aanpassing strategie saam met die konserwatiewe neerslag model noodsaaklik is ten einde realistiese resultate te behaal vir die sneeu opbou rondom of naby strukture. Sodoende word genoegsame vlakke van belangrike vloei verskynsels, soos die invloed van vloei divergensie, in ag geneem wat net so ‘n belangrik rol in neerslag speel soos vertikale afsetting.

We present axisymmetric hydrodynamical simulations of the long-term accretion of a rotating gamma-ray burst progenitor star, a "collapsar," onto the central compact object, which we take to be a black hole. The simulations were carried out with the adaptive mesh refinement code FLASH in two spatial dimensions and with an explicit shear viscosity. The evolution of the central accretion rate exhibits phases reminiscent of the long GRB [gamma]-ray and X-ray light curve, which lends support to the proposal by Kumar et al. (2008a,b) that the luminosity is modulated by the central accretion rate. In the first "prompt" phase, the black hole acquires most of its final mass through supersonic quasiradial accretion occurring at a steady rate of [scientific symbols]. After a few tens of seconds, an accretion shock sweeps outward through the star. The formation and outward expansion of the accretion shock is accompanied with a sudden and rapid power-law decline in the central accretion rate Ṁ [proportional to] t⁻²̇⁸, which resembles the L[subscript x] [proportional to] t⁻³ decline observed in the X-ray light curves. The collapsed, shock-heated stellar envelope settles into a thick, low-mass equatorial disk embedded within a massive, pressure-supported atmosphere. After a few hundred seconds, the inflow of low-angular-momentum material in the axial funnel reverses into an outflow from the thick disk. Meanwhile, the rapid decline of the accretion rate slows down, which is potentially suggestive of the "plateau" phase in the X-ray light curve. We complement our adiabatic simulations with an analytical model that takes into account the cooling by neutrino emission and estimate that the duration of the prompt phase can be ~ 20 s. The model suggests that the steep decline in GRB X-ray light curves is triggered by the circularization of the infalling stellar envelope at radii where the virial temperature is below 10¹⁰ K, such that neutrino cooling is inefficient and an outward expansion of the accretion shock becomes imminent; GRBs with longer prompt [gamma]-ray emission should have more slowly rotating envelopes. / text