The study aims to generate a simulated, ultra high-resolution climatology over the southwestern Cape of South Africa, and in particular the Stellenbosch wine producing region, by the dynamical downscaling of observed synoptic-scale circulation. A variable-resolution global model, the conformal-cubic atmospheric model (CCAM), and a multiple-nudging strategy are applied in order to reach this goal. CCAM is employed in stretched-grid mode as a regional climate model (RCM) to simulate climate for the period 1976-2005 at four different spatial resolutions. Nudging from coarse-resoltion (2.5° in latitude and longitude), the model was first applied at a 60 km resolution over southern Africa in order to obtain a simulation of the synoptic-scale circulation over the region. Two higher resolution simulations, at 8 km and 1 km resolution, were obtained consecutively over the western and southwestern Cape, nudging from the 60 km and 8 km simulations, respectively. Finally, a 200 m simulation was performed over the Stellenbosch region. Because of the high computational requirements of high-resolution runs, each progressively higher resolution simulation is performed over a progressively smaller area of interest over which the spatial resolution is high. The simulations verify well against observed datasets, and generally capture the important climatic features over the area of interest. The 60 km CCAM simulation gives a good representation of the synoptic scale weather over southern Africa, with realistic seasonal circulation patterns and rainfall percentages as well as intra-annual rainfall totals over various regions. The mesoscale climate over the Western Cape of South Africa is captured by the 8 km simulation, especially with respect to seasonal variations in temperature and rainfall percentages - although the actual rainfall over the southwestern tip of the Western Cape is severely underestimated. The ultra high-resolution simulated diurnal cycle of temperature, relative humidity and screen level wind speed compared well against observations for the month of February. The CCAM climate simulations might not be accurate enough for some of the very sensitive studies of the wine industry, but it can have great value for the demarcation of areas which are climatically suited for viticulture and some more general viticultural studies. Ultra high-resolution climate parameter maps are presented for 1976-2005. / Dissertation (MSc)--University of Pretoria, 2009. / Geography, Geoinformatics and Meteorology / Unrestricted

Spin-1/2 chains demonstrate some of the striking effects of interactions and quantum fluctuations in one-dimensional systems. The XXZ model has been used to study the unusual properties of anisotropic spin chains in an external magnetic field. The zero temperature phase diagram for this model exhibits a critical or quasi-long-range-ordered phase which is a realization of a Luttinger liquid. While many static properties of spin-1/2 chains have been explained by combinations of analytical techniques such as bosonization and Bethe ansatz, the standard approach fails in the calculation of some time-dependent correlation functions. I present a study of the longitudinal dynamical structure factor for the XXZ model in the critical regime. I show that an approximation for the line shape of the dynamical structure factor in the limit of small momentum transfer can be obtained by going beyond the Luttinger model and treating irrelevant operators associated with band curvature effects. This approach is able to describe the width of the on-shell peak and the high-frequency tail at finite magnetic field. Integrability is shown to affect the low-energy effective model at zero field, with consequences for the line shape. The power-law singularities at the thresholds of the particle-hole continuum are investigated using an analogy with the X-ray edge problem. Using methods of Bethe ansatz and conformal field theory, I compute the exact exponents for the edge singularities of the dynamical structure factor. The same methods are used to study the long-time asymptotic behavior of the spin self-correlation function, which is shown to be dominated by a high-energy excitation. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The Conformal C-Band/Multi-band Antenna project will support the AWS-3 auction by providing the technology to integrate C-Band or multi-band telemetry(TM) antennas on test articles such as missiles, weapons, or aircraft. These test articles would then provide C-Band or multi-band TM data to ground station receivers that are relocated to the C-Band frequency range through the AWS-3 Spectrum Relocation Fund program. This project would advance the technology of antennas in the C-Band region for test article TM integration. Successful use of C-Band and Multi-Band antennas for aeronautical mobile telemetry (AMT) on test and training ranges is dependent on the advancement of key technologies. This paper will detail the technology areas being matured by this project as well as the capabilities to be demonstrated.

In this dissertation, a low energy theory approach is applied to the studies of Dark Matter direct detection experiments and two-dimensional Quantum Chromodynamics (QCD) spectra. We build a general framework of non-relativistic effective field theory of Dark Matter direct detection using non-relativistic operators. Any Dark Matter particle theory can be translated into the coefficients of an effective operator and any effective operator can be related to a most general description of the nuclear response. Response functions are evaluated for common Dark Matter targets. Based on the effective field theory we perform an analysis of the experimental constraints on the full parameter space of elastically scattering Dark Matter. We also formulate an analytic approach to solving two-dimensional gauge theories. We find that in theories with confinement, in a conformal operator basis, the decoupling of high scaling-dimension operators from the low-energy spectrum occurs exponentially fast in their scaling-dimension. Consequently the low-energy spectrum of a strongly coupled system like QCD can be calculated using a truncated conformal basis, to an accuracy parametrized exponentially by the cutoff dimension. We apply the conformal basis approach in two models, a two-dimensional QCD with an adjoint fermion at large N, and a two-dimensional QCD with a fundamental fermion at finite N. It is shown that the low energy spectrum converges efficiently in both cases.

Quantum Field Theory (QFT) is the language that describes a wide spectrum of physics. However, it is notoriously hard at strong coupling regime. We approach this problem in an old Quantum Mechanical method - keep a finite number of states and diagonalize the Hamiltonian as a finite-size matrix. To study a QFT, we take the Hamiltonian to be the Conformal Field Theory as the Ultraviolet fixed point of the theory's Renormalization Group Flow, deformed by a relevant operator. We use a recent framework known as the Lightcone Conformal Truncation (LCT), where we use conformal basis and lightcone quantization. As an application of the method, we study the two dimensional Supersymmetric (SUSY) Gross-Neveu-Yukawa Model. The model is expected to have a critical point in the universality class of tri-critical Ising model, a massive phase and a massless SUSY-breaking phase. We use the LCT to compute the spectrum and the spectral density of the theory at all couplings and map the entire phase diagram.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第22996号 / 理博第4673号 / 新制||理||1670(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 高柳 匡, 教授 杉本 茂樹, 教授 田中 貴浩 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

<p>Current small satellite propellant tank design is driven by three factors: volume op-timization, manufacturing capability, and propellant management. Conformal propellanttanks offer solutions to the design challenges of optimizing satellite volume and manufac-turing costs. Conformal propellant tank designs that meet these challenges have unknowneffects on propellant management. Compounding this uncertainty is the industry shift to-wards new green propellants with large contact angles. Improper propellant managementcan deliver gas to a thruster or leave propellant trapped away from the tank outlet whiledraining. Both scenarios reduce the lifespan of satellites.</p> <p>Stamping is one manufacturing process that can produce tanks that optimize volumeand are relatively easy to manufacture. The effects of the stamping process on tank shapeand propellant management is evaluated through testing four different tank geometries. Thestamping process sometimes leaves behind a seam where two sides of a tank are joinedtogether. A total of six tank and vane combinations are tested. One set of traditional tanksserve as a control. Three tanks tested share vane geometry and have different interiors toevaluate the effects of the stamping process on propellant management. The first tank hasa smooth interior, the second has a seam at the joints and the third tank has a seam andridges for increased stiffness. The last two tanks have an interior in the shape of an arc andhave different vanes. The experiment is flown on the ZeroG airplane to test the tank andvane designs in a weightless environment.</p> <p>The experiment consists of a payload rack, eleven experimental pods and one powerdistribution pod. Each experimental pod is designed to be modular and independent fromall other experimental pods. Each experimental pod hosts a camera, electrical box, secondcontainment and fluid system with four tanks.</p> <p>The results of this study show no discernible difference could be observed between tankswith or without a seam from the stamping process. When ridges are added to a tank thatare parallel to the contact line, liquid may not wick into the ridge if it is dry. If the ridgeis wet the liquid spreads out on the surface of the tank further. The differences betweenpropellant positioning for zero and nonzero contact angle fluids are discussed</p> <p><br></p>

The basic cube satellite (CubeSat) is a modern small satellite that has a standard size of about one liter (the 1U CubeSat). Three 1U CubeSats could be stacked to form a 3U CubeSat. Their low-cost, short development time, and ease of deployment make CubeSats popular for space research, geographical information gathering, and communication applications. An antenna is a key part of the CubeSat communication subsystem. Traditionally, antennas used on CubeSats are wrapped-up wire dipole antennas, which are deployed after satellite launch. Another antenna type used on CubeSats is the patch antenna. In addition to their low gain and efficiency, deployable dipole antennas may also fail to deploy on satellite launch. On the other hand, a solid patch antenna will compete for space with solar cells when placed on a CubeSat face, interfering with satellite power generation. Slot antennas are promising alternatives to dipole and patch antennas on CubeSats. When excited, a thin slot aperture etched on a conductive sheet (ground plane) is an efficient bidirectional radiator. This open slot antenna can be backed by a reflector or cavity for unidirectional radiation, and solar cells can be placed in spaces on the ground plane not occupied by the slot. The large surface areas of 3U CubeSats can be exploited for a multifunctional antenna by integrating multiple thin slot radiators, which are backed by a thin cavity on the CubeSat surfaces. Solar cells can then be integrated on the antenna surface. Polarization diversity and frequency diversity improve the overall performance of a communication system. Having a single radiating structure that could provide these diversities is desired. It has been demonstrated that when a probe excites a square cavity with two unequal length crossed-slots, the differential radiation from the two slots combines in the far-field to yield circular polarization. In addition, it has been shown that two equal-length proximal slots, when both fed with a stripline, resonate at a frequency due to their original lengths, and also resonate at a lower frequency due to mutual coupling between the slots, leading to a dual-band operation. The multifunctional antenna designs presented are harmonizations and extensions of these two independent works. In the multifunctional antenna designs presented, multiple slots were etched on a 83 mm x 340 mm two-layer shallow cavity. The slots were laid out on the cavity such when the cavity was excited by a probe at a particular point, the differential radiation from the slots would combine in the far-field to yield Left-Handed Circular Polarization (LHCP). Furthermore, when the cavity was excited by another probe at an opposite point, the slots would produce Right-Handed Circular Polarization (RHCP). In addition, as forethought, these slots were laid out on the cavity such that some slots were close together enough to give Linearly Polarized (LP) dual-band operation when fed with a stripline. This antenna was designed and optimized via computer simulations, fabricated using Printed Circuit Board (PCB) technology, and characterized using a Vector Network Analyzer (VNA) and NSI Far Field Systems.

Indiana University-Purdue University Indianapolis (IUPUI) / Plastic injection molding is a versatile process and a major part of the present plastic manufacturing industry. Traditional die design is limited to straight (drilled) cooling channels, which dont impart optimal thermal (or thermos-mechanical) per- formance. Moreover, reducing the cycle time in plastic injection molding has become significantly important to the industry nowadays. One approach that has been pro- posed is to use conformal cooling channels. With the advent of additive manufacturing technology, injection molding tools with conformal cooling channels are now possible. However, optimum conformal channels based on thermo-mechanical performance are not found. This study proposes a design methodology to generate optimized design configurations of such channels in plastic injection molds. Numerical models have been developed here to represent the thermo-mechanical behavior of the molds and predict the stress and cooling time. The model is then validated experimentally and used in conjunction with DOE (Design of Experiments) to study the effect of differ- ent design parameters of the channels on the die performance. Design of experiments (DOEs) is used to study the effect of critical design parameters of conformal channels as well as their cross section geometries. These DOEs are conducted to identify op- timal designs of conformal cooling channels which can be incorporated into injection molds that are used to manufacture cylindrical and conical shapes of plastic parts. Though these are simplified forms, the study provides useful insight into the poten- tial deign parameters for all kind of injection molds.Based on the DOEs, designs for best thermo-mechanical performance are identified (referred to as ”optimum”). The optimization study is basically a trade-off and the solution is based on a specific sample size. This approach is highly result-oriented and provides guidelines for selecting optimum design solutions given the plastic part thickness.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18794号 / 理博第4052号 / 新制||理||1583(附属図書館) / 31745 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 川合 光, 准教授 福間 將文, 教授 田中 貴浩 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM