One of the greatest technological challenges of the world today is reducing the size and weight of the existing products to make them portable. Specifically, in electric vehicles such as electric cars, UAVs and aero planes, the size of battery chargers and inverters needs to be reduced so as to make space for more parts in these vehicles. Electromagnetic Interference (EMI) filters take up a more than 80 % of these power converters, the size of these filters can be reduced by pushing the switching frequency higher. High frequency operation (> 300 kHz) leads to a size in reduction of EMI filters though it also leads to an increase in switching losses thus compromising on efficiency. Thus, soft switching becomes necessary to reduce the losses, adding more electrical components to the converter to achieve soft switching is a common method. However, it increases the physical complexity of the system. Hence, advanced control methods are adopted for today's power converters that enable soft switching for devices specifically ZVS turn-on as the turn-off losses of next generation WBG devices are negligible. Thus, the goal of this research is to discover novel switching algorithms for soft turn-on. The state-of the-art control methods namely CRM and TCM achieve soft turn-on by enabling bi-directional current such that the anti-parallel body diode starts conducting before the device is turned on. CRM and TCM result in variable switching frequency which leads to asynchronous operation in multi-phase and multi-converter systems. Hence, TCM is modified in this dissertation to achieve constant switching frequency, as the goal of this research is to be able to achieve ZVS turn-on for a three-phase converter. Further, Triangular Current Mode (TCM) to achieve soft switching and phase synchronization for three-phase two-level converters is proposed. It is shown how soft switching and sinusoidal currents can be achieved by operating the phases in a combination of discontinuous conduction mode (DCM), TCM and clamped mode. The proposed scheme can achieve soft switching ZVS turn-on for all the three phases. The algorithm is tested and validated on a GaN converter, 99% efficiency is achieved at 0.7 kW with a density of 110 W/in3. The discussion of TCM in current literature is limited to unity power factor assumption, however this limits the algorithm's adoption in real world applications. It is shown how proposed TCM algorithm can be extended to accommodate phase shift with all the three phases operating in a combination of DCM+TCM+Clamped modes of operation. The algorithm is tested and validated on a GaN converter, 99% efficiency is achieved at 0.7 kVA with a density of 110 W/in3. TCM operation results in 33 % higher rms current which leads to higher conduction losses, as WBG devices have lower on-resistance, these devices are the ideal candidates for TCM operation, hence to accurately obtain the device parameters, a detailed device characterization is performed. Further, proposed TCM+DCM+Clamped control algorithm is extended to three-level topologies, the control is modified to extract the advantage of reduced Common Mode Voltage (CMV) switching states of the three-level topology, the switching frequency can thus be pushed to 3 times higher as compared to state-of-the-art SVPWM control while maintaining close to 99 % efficiency. Two switching schemes are presented and both of them have a very small switching frequency variation (6%) as compared to state-of-the-art methods with >200% switching frequency variation. / Doctor of Philosophy / Power supplies are at the heart of today's advanced technological systems like aero planes, UAVs, electrical cars, uninterruptible power supplies (UPS), smart grids etc. These performance driven systems have high requirements for the power conversion stage in terms of efficiency, density and reliability. With the growing demand of reduction in size for electromechanical and electronic systems, it is highly desirable to reduce the size of the power supplies and power converters while maintaining high efficiency. High density is achieved by pushing the switching frequency higher to reduce the size of the magnetics. High switching frequency leads to higher losses if conventional hard switching methods are used, this drives the need for soft switching methods without adding to the physical complexity of the system. This dissertation proposes novel soft switching techniques to improve the performance and density of AC/DC and DC/AC converters at high switching frequency without increasing the component count. The concept and the features of this new proposed control scheme, along with the comparison of its benefits as compared to conventional control methodologies, have been presented in detail in different chapters of this dissertation.

Using a general, unsteady, nonlinear vortex lattice method, the aerodynamic loads have been found on a 75° delta wing with and without leading edge vortex flaps. The flap had an area approximately 26 percent of the wing area with a constant chord of 6.7 percent of the wing mean aerodynamic chord and was deflected at 30°. Results for lift, drag, axial force, and pitching moment coefficients are compared with experimental data and show very good agreement. Individual pressure difference coefficients along the wing and flap are also presented and compared with experimental data. Overall, the method shows the leading edge vortex flap to be very effective in reducing drag while maintaining lift comparable to that of the plain wing. / Master of Science

Com base especialmente no pensamento da arte-educadora Ana Mae Barbosa de um lado e de outro do educador Paulo Freire, essa Dissertação procura apresentar e refletir sobre o trabalho de Arte-Educação e Educação Ambiental, desenvolvido a partir de uma perspectiva interdisciplinar envolvendo educação e conservação ambiental e o ensino pós-moderno (ou contemporâneo) de arte no âmbito das ações do Programa de Educação e Conservação Ambiental Chão Verde Terra Firme, que, na sua quarta edição, no ano de 2006 com desdobramentos em 2007, 2008 e 2009, envolveu professores da região do Vale do Rio Juquery e Serra da Cantareira, localizada no segmento norte-noroeste da região metropolitana de São Paulo. / Based especially on the thought of art-educator Ana Mae Barbosa on one side and on the other hand the educator Paulo Freire, this paper aims to present and reflect on the work of Art Education and Environmental Education, developed from an interdisciplinary perspective involving education and environmental conservation and post-modern (or contemporary) art teaching in the context of the actions of the Education Program and Environmental Conservation \"Chão Verde Terra Firme\", which in its fourth edition in 2006 with unfold of the shares in 2007, 2008 and 2009, involved teachers from Vale do Rio Juquery and Serra da Cantareira, located in the north-northwest segment of the metropolitan region of Sao Paulo.

Made available in DSpace on 2016-07-27T13:54:20Z (GMT). No. of bitstreams: 1 Elaine Cristina de Almeida Sleiman.pdf: 9124346 bytes, checksum: 7b3a36944ed58f3c47804b18b139b9f5 (MD5) Previous issue date: 2009-03-30 / The purpose of this research is to investigate a methodological proposal of music teaching, whereas it s one of the art s languages to be applied to educators as an exercise with no specific formation. The theme election was motivated by research s reports where is evidenced that Art educators, in many cases, doesn t have a specific formation in the area. In this manner, taking into consideration the relevance of Art in school curriculum and the concrete reality of nonqualified educators, this paper consists of the application of a Musical Education methodology at the classroom, preceded by a preparing of the class educator program. The research was conducted according to characteristics of a didacticeducative trial, derived of Vygotsky searches, that consists of keep up with the educator s work, with a 4º year students group on primary school of private Goiania education system. The trial was based on a teaching plan with music activities, within a period of seven weeks, elaborated jointly by the researcher and the group s educator. The methodological proposal had its theoretical supports on A. M. Barbosa work, geared towards the Art and Education teaching, on Maria T., O. Fonterrada and Koellreutter with their theorization of music teaching, as the theoretical-methodological orientations of historic-cultural theory, mainly on L.S. Vygotsky and V. Davydov formulation. Besides the didactic-educative trial, including class observation, other procedures were realized as the educator s interview, observation of the school and analysis of episodes referring to educator s mind development. The data analysis was orientated with the purpose to verify effects of the researcher s action on preparing the educator based on the teaching methodology and the educator performance on the development of students mind process. / O propósito desta pesquisa foi investigar uma proposta metodológica de ensino de música, enquanto uma das linguagens das aulas de arte a ser aplicada a educadores em exercício sem formação específica. A escolha deste tema foi motivada por relatos de pesquisa em que se constata que educadores que trabalham com o ensino da Arte, em muitos casos, não têm formação específica nessa área. Dessa forma, considerando-se a relevância da presença da Arte nos currículos escolares e a realidade concreta de existência de educadores não habilitados, este trabalho consistiu da aplicação de uma metodologia de ensino de Educação Musical na sala de aula, precedida de um programa de preparação da educadora da classe. A pesquisa foi conduzida conforme as características de um experimento didático-formativo, derivado das pesquisas de Vygotsky, que consiste do acompanhamento assistido do trabalho de uma educadora, numa classe de educandos do 4º ano do ensino fundamental da rede privada de ensino de Goiânia. O experimento teve por base um plano de ensino com atividades de música, num período de sete semanas, elaborado conjuntamente pela pesquisadora e pela educadora da classe. A proposta metodológica teve como suporte teórico a obra de A. M. Barbosa direcionada ao ensino da Arte e Educação, de Marisa T. de O. Fonterrada e de Koellreutter, na teorização do ensino da Música, bem como as orientações teórico-metodológicas da teoria histórico-cultural, principalmente na formulação de L.S.Vygotsky e V. Davydov. Além do experimento didático-formativo, que inclui a observação de aulas, foram utilizados outros procedimentos como a entrevista com a educadora da classe, observação da escola e análise de episódios referentes ao desenvolvimento mental dos educandos. A análise dos dados foi orientada para verificar os efeitos da ação da pesquisadora de preparação da educadora na metodologia de ensino e da atuação da educadora no desenvolvimento dos processos mentais dos educandos.

Com base especialmente no pensamento da arte-educadora Ana Mae Barbosa de um lado e de outro do educador Paulo Freire, essa Dissertação procura apresentar e refletir sobre o trabalho de Arte-Educação e Educação Ambiental, desenvolvido a partir de uma perspectiva interdisciplinar envolvendo educação e conservação ambiental e o ensino pós-moderno (ou contemporâneo) de arte no âmbito das ações do Programa de Educação e Conservação Ambiental Chão Verde Terra Firme, que, na sua quarta edição, no ano de 2006 com desdobramentos em 2007, 2008 e 2009, envolveu professores da região do Vale do Rio Juquery e Serra da Cantareira, localizada no segmento norte-noroeste da região metropolitana de São Paulo. / Based especially on the thought of art-educator Ana Mae Barbosa on one side and on the other hand the educator Paulo Freire, this paper aims to present and reflect on the work of Art Education and Environmental Education, developed from an interdisciplinary perspective involving education and environmental conservation and post-modern (or contemporary) art teaching in the context of the actions of the Education Program and Environmental Conservation \"Chão Verde Terra Firme\", which in its fourth edition in 2006 with unfold of the shares in 2007, 2008 and 2009, involved teachers from Vale do Rio Juquery and Serra da Cantareira, located in the north-northwest segment of the metropolitan region of Sao Paulo.

L’objet de cette thèse est de proposer un régime fiscal applicable à l’imposition des revenus passifs dans les situations triangulaires internationales. La première partie est consacrée à analyser la nature objective du risque de double imposition. Ce sont les situations triangulaires « passives » ou « subies ». La seconde partie est consacrée à analyser des situations triangulaires « actives » ou « choisies » qui peuvent être propices à la mise en place de structures fiscalement « avantageuses ». L’étude est complétée par des propositions de modification du Modèle de convention fiscale. / The purpose of this work is to propose a tax treatment applicable to passive income in international triangular tax cases. The first part of the study is dedicated to the analyses of the double tax exposure. These are “passive” triangular cases or “incurred”, where potential double tax and uncertainty creates an issue for economic growth. The second part of the study is dealing with “active” triangular situations that may be motivated by the tax benefit resulting from these structures. The conclusion of our study will include proposals to amend the OECD treaty Model.

In this PhD thesis, the physics of vacancies in two-dimensional ordered Heisenberg antiferromagnets is investigated. We use semi-classical methods to study the influence of a single vacancy in long-range ordered states, with a focus on non-collinear order. Here, on a classical level, a magnetic distortion is created as the spins readjust in response to the vacancy. We use the non-collinear $120^\\circ$ state on the frustrated triangular lattice as an example, where we determine the impurity contributions to the magnetization and susceptibility. An important discovery is the vacancy moment not being quantized due to non-universal partial screening. The resulting effective moment $m_0 \\ll S$ can be observed as a fractional prefactor to an impurity-induced Curie response $m_0^2/(3k_BT)$ at finite temperature. This is in sharp contrast to collinearly ordered states. Here the moment is always quantized to the bulk spin value, $m_0=S$. Furthermore, we present a detailed analysis of the vacancy-induced distortion cloud. Due to Goldstone modes, it decays algebraically as $r^{-3}$ with distance $r$ to the vacancy. Using leading-order $1/S$-expansion, we determine the quantum corrections to both size and direction of the distorted magnetic moments. Secondly, we study the same problem in the presence of an external magnetic field $h$, both for the square and triangular lattice. For the triangular lattice we use a biquadratic exchange term $K$ to stabilize a unique ground state from a degenerate manifold. The finite-field vacancy moment $m(h)$ is generated by field-dependent screening clouds, as different non-collinear bulk states evolve with increasing field. These distortion clouds decay exponentially on a magnetic length scale $l_h\\propto 1/h$. Most importantly, we find that the magnetic-field linear-response limit $h \\rightarrow 0^+$ is generically singular for $SU(2)$ ordered local-moment antiferromagnets, as the vacancy moment in zero field differs fundamentally from even an infinitesimal but finite field, $m(h \\rightarrow 0^+)\\neq m_0$. Moreover, a part of the screening cloud itself becomes universally singular. Particularly for spin-flop states, this leads to a semi-classical version of perfect screening. We present general arguments to support these claims, as well as microscopic calculations. Another remarkable result is an impurity-induced quantum phase transition for overcompensated vacancies in the $M=1/3$ plateau phase on the triangular lattice with $K<0$. We close our analysis with a discussion about important limits for finite vacancy concentrations, as well as a possible experimental verification of our predictions.

Thesis (M.Com. (Taxation))--University of the Witwatersrand, Faculty of Commerce, Law and Management, School of Accountancy, 2014. / With the international platform for cross border investment and economic development growing year on year at a steady pace, it has become apparent that bilateral income tax treaties do not always operate effectively in multilateral tax situations. Global transactions involving more than two states are certainly not uncommon and it could be said that the most fundamental issue in international taxation is double taxation resulting from the taxing rights of different tax jurisdictions that ‘overlap’ with regard to, generally speaking, one taxpayer or one declared income stream. Multilateral tax situations, commonly known as triangular cases, occur where tax incidence on a particular stream of income is triggered in three countries. These situations typically arise where a person who is a tax resident in two respective countries for tax purposes (a dual resident), or a person who is a tax resident in one country and has a permanent establishment in another, is earning revenue of which the source is in a third country. Taxing rights and jurisdictions of the three countries involved could potentially be in conflict with each other and therefore such situations may bring about lawful international triangular taxation or double taxation which will inevitably discourage enterprises from continuing investment and development internationally. Broad multilateral treaties in the income tax arena are not common1, and most treaties are still of a bilateral nature, i.e. generally addressing tax scenarios where only two specific countries are involved. The Organisation for Economic Cooperation and Development’s (’the OECD’)Model Tax Convention states this: There are no reasons to believe that the conclusion of a multilateral tax convention involving all Member countries could now be considered practicable. The Committee therefore considers that bilateral conventions are still a more appropriate way to ensure the elimination of double taxation at the international level.2

Computational modeling offers better insight into a wide range of bioelectrical and biomechanical problems with improved tools for the design of medical devices and the diagnosis of pathologies. Electromagnetic modeling at low and high frequencies is particularly necessary. Modeling electromagnetic, structural, thermal, and acoustic response of the human body to different internal and external stimuli is limited by the availability of numerically efficient computational human models. This study describes the development to date of a computational full-body human model - Visible Human Project (VHP) - Female Model. Its unique feature is full compatibility both with MATLAB and specialized FEM computational software packages such as ANSYS HFSS/Maxwell 3D. This study also describes progress made to date in using the newly developed tools for segmentation. A visualization tool is implemented within MATLAB and is based on customized version of the constrained 2D Delaunay triangulation method for intersecting objects. This thesis applies a VHP - Female Model to a specific application, transcranial Direct Current Stimulation (tDCS). Transcranial Direct Current Stimulation has been beneficial in the stimulation of cortical activity and treatment of neurological disorders in humans. The placement of electrodes, which is cephalic versus extracephalic montages, is studied for optimal targeting of currents for a given functional area. Given the difficulty of obtaining in vivo measurements of current density, modeling of conventional and alternative electrode montages via the FEM has been utilized to provide insight into the tDCS montage performance. An insight into future work and potential areas of research, such as study of bone quality have been presented too.

行動通訊網路之國際漫遊(以下簡稱：漫遊)的信令傳遞方式，從早期的通信衛星發展至目前的海底纜線，都屬於高維護成本的電信基礎設施，導致漫遊通話費用成本居高不下。隨著行動通訊網路技術發展，無形中促使OTT（Over The Top）的應用逐漸廣泛，甚至取代原本漫遊通話模式。即便如此，漫遊通話節費產品依然盛行，其主要原因是OTT服務無法提供優於目前行動通訊網路所擁有的特性：高通話品質、高移動性以及通話雙方不受應用軟體或終端裝置型號之限制（如Line無法與微信互通）。 由於漫遊的話務必須透過本地端服務網路或國際合作營運商的協議路由，才能順利將信令送達受話方，如此的程序卻造成Tromboning和Triangular等路由問題，對營運商而言，無形中衍生國際營運商合作的路由接續費用等相關成本。為改善上述問題，本論文的研究方法在不增加電信核心網路元件的基礎架構上使用漫遊閘道，分流處理目前行動通訊網路之漫遊的信令傳遞。採用動態更新漫遊用戶資料機制，降低各電信核心網路元件的運算資源，使漫遊的話務能採用更直接的路徑方式進行路由。 本研究所提出的方法，根據數學理論推導驗證可以發現，漫遊路由成本，不論是路由所需經過的國家數、網路元件數以及營運商連結數等，都能有效降低。模擬實驗結果也顯示，本研究方法能有效降低漫遊呼叫接通的時間，並能提升行動通訊網路前端網路元件的運算效能。在避免Tromboning和Triangular等路由問題的同時，降低營運商的話務路由成本，進而降低漫遊通話費用，提升用戶對漫遊通話使用率，達成雙贏局面。 / The ways of transferring signaling of international roaming, abbreviated to roaming in the following, in mobile communication network evolve from satellite communications, submarine cable communications, etc. The huge maintenance cost of telecommunication infrastructure results in high charge of a roaming call. Through the advancement of mobile communication network technologies, the emergent Over The Top (OTT) applications had been widely spread and began to replace the ways of legacy roaming calls. However, the saving call products still popular is due to OTT services are inferior to those of mobile communication in terms of voice quality and mobility. Apart from this, both parties of OTT services are subject to the same application software, e.g. LINE cannot communicate with WeChat. Since roaming traffic should be delivered through the routing protocol between local service network and international cooperative operators, it may cause Tromboning and Triangular problems. Operators, should thus increase the cost of interconnection due to the corporation among international operators. To resolve the problems, we propose to use roaming gateways based on the underlying infrastructure without adding components to the existing telecommunication core network. Roaming gateways can assist in separate processing of roaming signals delivery of the current mobile communication networks. The proposed method adopts the current registration model when roaming users visit a service network. Aside from this, the method dynamically updates users’ data in order to reduce the use of computing resources of core network components. The method is proved to be able to choose more direct paths in making roaming calls. The proposed method is verified by both mathematical analysis and simulations. The mathematical analysis proves that the proposed method is able to reduce roaming routing cost in terms of numbers of countries, network components and interconnected operators. The simulations show that the proposed method is able to shorten the answering time of roaming calls and enhance the computation efficiency of the front-end components of mobile communication network. In summary, the proposed method is able to solve the routing problems of Tromboning and Triangular as well as reduce the traffic routing cost of operators. As the result, the operators will be able to offer better tariff to users.