This dissertation presents the analysis and development of an innovative semiconductor device and topology for the high power current source converter (CSC). The CSC is very attractive in high power applications due to its lower output dv/dt, easy regeneration capability and implicit short-circuit protection. Traditionally, either a symmetrical gate turn-off (GTO) thyritor or an asymmetrical GTO in series with a diode is used as the power switch in the CSC. Since the GTO has a lower switching speed and requires a complicated gate driver, the symmetrical GTO based CSC usually has low dynamic response speed and low efficiency. To achieve high power rating, fast dynamic response speed and low harmonics, an advanced semiconductor device and topology are needed for the CSC. Based on symmetrical GTO and power MOSFET technologies, a symmetrical emitter turn-off (ETO) thyristor is developed that shows superior switching performance, high power rating and reverse voltage blocking capability. The on-state characteristics, forced turn-on characteristics, forced turn-off characteristics and the load-commutated characteristics are studied. Test results show that although the load-commutation loss is high, the developed symmetrical ETO is suitable for use in high power CSC due to its low conduction loss, fast switching speed and reverse voltage blocking capability. The snubberless turn-on capability is preferred for a semiconductor device in a power conversion system, and can be achieved for devices with forward biased safe operation area (FBSOA). The FBSOA of the ETO is investigated and experimentally demonstrated. The ETO device has excellent FBSOA due to the negative feedback provided by the emitter switch. However, the FBSOA for a large area ETO is poor. A new ETO concept is therefore proposed for future development in order to demonstrate the FBSOA over a large area device. To improve the turn-on performance of the large area ETO, a novel concept, named the transistor-mode turn-on, is proposed and studied. During the transistor-mode turn-on process, the ETO behaves like a transistor instead of a thyristor. Without a snubber, the transistor-mode turn-on for the ETO is hard to achieve. Through the selection of a proper gate drive and di/dt snubber, the transistor-mode turn-on can be implemented, and the turn-on performance for the ETO can be dramatically improved. To increase the power rating of the CSC without degrading the utilization of power semiconductor devices, a novel multilevel CSC, named the parallel-cell multilevel CSC, is proposed. Based on a six-switch CSC cell, the parallel-cell multilevel CSC has the advantages of high power rating, low harmonics, fast dynamic response and modularity. Therefore, it is very suitable for high power applications. The power stage design, modeling, control and switching modulation scheme for a parallel-cell multilevel CSC based static var compensator (STATCOM) are analyzed and verified through simulation. / Ph. D.

Within the set of all vehicle crashes that occur annually, of intersection-related crashes are over-represented. The research conducted here uses an empirical approach to study driver behavior at intersections, in a naturalistic paradigm. A data-mining algorithm was used to aggregate the data from two different naturalistic databases to obtain instances of unprotected turns at the same intersection. Several dependent variables were analyzed which included visual entropy, mean-duration of glances to locations in the driver's view, gap-acceptance/rejection time. Kinematic dependent variables include peak/average speed, and peak longitudinal and lateral acceleration. Results indicated that visual entropy and peak speed differs amongst drivers of the three age-groups (older, middle-age, teens) in the presence of traffic in the intersecting streams while negotiating a left turn. Although not significant, but approaching significance, were differences in gap acceptance times, with the older driver accepting larger gaps compared to the younger teen drivers. Significant differences were observed for peak speed and average speed during a left turn, with younger drivers exhibiting higher values for both. Overall, this research has resulted in contribution towards two types of engineering application. Firstly, the analyses of traffic levels, gap acceptance, and gap non-acceptance represented exploratory efforts, ones that ventured into new areas of technical content, using newly available naturalistic driving data. Secondly, the findings from this thesis are among the few that can be used to inform the further development, refinement, and testing of technology (and training) solutions intended to assist drivers in making successful turns and avoiding crashes at intersections. / Master of Science

No / Fusing two key concerns of contemporary sociology: globalization and its discontents, and the 'complexity turn' in social theory, authors Chesters and Welsh utilize complexity theory to analyze the shifting constellation of social movement networks that constitute opposition to neo-liberal globalization. They explore how seemingly chaotic and highly differentiated social actors interacting globally through computer mediated communications, face-to-face gatherings and protests constitute a 'multitude' not easily grasped through established models of social and political change. Drawing upon extensive empirical research and utilizing concepts drawn from the natural and social sciences this book suggests a framework for understanding mobilization, identity formation and information flows in global social movements operating within complex societies. It suggests that this 'movement of movements' exhibits an emergent order on the edge of chaos, a turbulence that is recasting political agency in the twenty-first century.

Silicon carbide (SiC) outperform Si chips in terms of high blocking voltage capability, low on-resistance, high-temperature operation, and high switching frequency. Several SiC MOSFETs are usually paralleled to increase current capability, considering cost effectiveness and manufacturability. For a SiC power module with current rating higher than 100 A, high did/dt and dvds/dt could possibly cause cross-turn-on (crosstalk-induced turn-on) through the gate-to-drain capacitance Cgd of the MOSFET dies and the package inductances. Mismatches in threshold voltage (Vth) up to 33% have been observed among paralleled SiC MOSFETs. This leads to unbalanced transient peak currents and switching energies. Both cross-turn-on and current unbalance degrade the reliability of a power module. Increasing the immunity to cross-turn-on while maintaining the similar switching energies and balancing the transient peak currents below 10% without sacrificing the voltage stress are the goals of this work. Development of a SPICE model free of non-convergence – A simulation model for a SiC power module is necessary for evaluations of cross-turn-on and current unbalance; however, most SiC power modules do not have models. No existing modeling methods discuss how to build an accurate SPICE model that is free of non-convergence when hundreds of parasitic inductances are present. A modeling process is introduced for paralleled MOSFETs encapsulated in a power module that gives access to both the internal channel current and voltage of each bare die inside the package. This model is free of non-convergence and accurate. Parasitic ac resistances, dc resistances, and ac inductances are extracted by Q3D Extractor. Non-convergence is avoided by including the ac resistance of the conduction trace in the model. Also, a series model which is set default in Q3D Extractor is converted to parallel model to accurately reflect how the current flows through the dc and ac resistances of the trace. A complete SPICE model of a commercial SiC power module was derived and validated by experiments. The error between predicted turn-on peak current of the developed model and that of the experimental data is 2%, significantly lower than the 28% difference between prediction result of commercial model and experimental data. Detection of internal cross-turn-on – Terminal current of a power module does not reflect the internal channel current due to the numerous parasitic inductances of the package. No existing method is able to detect the cross-turn-on in a power module since dies are usually encapsulated and the channel currents are hard to measure. A nonintrusive method to identify cross-turn-on based on the changing ringing current is developed. The detection method was analyzed theoretically and validated by experiments using a 1.2-kV SiC module. The negative drive voltage and gate resistance for safe operation can be determined by the detection method. Influence of layout symmetry on immunity to cross-turn-on – Gate resistance, gate-to-drain capacitance of the MOSFET, slew rate of drain-to-source voltage, and temperature have been recognized as the only elements impacting the immunity to cross-turn-on for a single chip and module. Layout symmetry is newly discovered to be another factor that contributes to the immunity. Asymmetrical and symmetrical modules following commercial layouts were tested by a double pulse tester. The peak cross-turn-on currents, high-side switching energy, and total switching energy at various input voltages, low-side gate resistances, and load currents are normalized for comparison. The peak cross-turn-on current of the symmetrical module is 84% lower than that of the asymmetrical module at nominal condition. Longer power-loop and gate-drive loop are required to achieve symmetrical layout for more than two dies in parallel. This increases the low-side switching energy of the symmetrical module. The total switching energies of the two modules are similar. In this case, a symmetrical layout is still recommended since current stress caused by cross-turn-on is much smaller in symmetrical module than in the asymmetrical module and chances to have shoot-through between the high side and the low side are reduced. Magnetic integration into a power module for current balancing – Existing power modules do not have balanced transient currents when threshold voltage mismatch exists. A module with integrated coupled inductors was designed, fabricated, and validated to be effective to balance the currents without sacrificing voltage stress and switching energy. The designed integrated coupled inductors achieve inverse coupling by utilizing the copper trace of the substrate and bond wires and have the following features: size comparable to the silicon carbide (SiC) die, coupling coefficient higher than 0.98, tens of nH operating at tens of MHz, and current rating of tens of Amperes. The coupled inductors with the magnetic material of low-temperature co-fired ceramics (LTCC) are compatible with existing packaging technology for module fabrication. The effectiveness of reducing transient-current mismatch at various input voltages, load currents, and gate resistances was verified by experiments. Compared with the baseline module following commercial practice, the module with integrated coupled inductors reduces current unbalance from 36% to 6.4% and turn-on-energy difference from 28% to 2.6% while maintaining the same total switching energy and a negligible change of voltage stress. / Ph. D. / A silicon carbide (SiC) power module with high di_d/dt and dv_ds/dt could possibly cause crossturn-on (crosstalk-induced turn-on) through the gate-to-drain capacitance C_gd of the MOSFET dies and package inductances. Mismatches in threshold voltage (V_th) up to 33% have been observed among paralleled SiC MOSFETs. This leads to unbalanced transient peak currents. Both crossturn-on and current unbalance degrade the reliability. Increasing the immunity to cross-turn-on while maintaining the similar switching energies and balancing the transient peak currents below 10% without sacrificing the voltage stress are the goals of this work. The development of a SPICE model for a SiC power module is necessary for evaluations of cross-turn-on and current unbalance; however, no existing modeling methods discuss how to build an accurate SPICE model of a power module free of non-convergence when hundreds of parasitic inductances are present. The modeling method to overcome these challenges is introduced. The error between predicted turn-on peak current of the developed model and that of the experimental data is 2%, significantly lower than the 28% difference between prediction result of commercial model and experimental data. No existing method is able to detect the cross-turn-on in a power module since the dies are usually vi encapsulated and the channel currents are hard to measure. A nonintrusive method to identify the cross-turn-on based on the changing ringing current is developed. The detection method was analyzed theoretically and validated by experiments using a 1.2-kV SiC module. Layout symmetry is newly discovered to be another factor that contributes to the immunity. The peak cross-turn-on current of the symmetrical module is 84% lower than that of the asymmetrical module at nominal condition. The symmetrical layout greatly decreases cross-turn-on currents without increasing total switching energy. Power modules in the market cannot have balanced transient currents when mismatches in threshold voltage V_th exist. A module with integrated coupled inductors was designed, fabricated, and validated to be effective to balance the currents with the presence of V_th mismatch. Compared with the baseline module following commercial practice, the module with integrated coupled inductors reduces current unbalance from 36% to 6.4% and turn-on-energy difference from 28% to 2.6% while maintaining the same total switching energy and negligible change of voltage stress.

The rise of ubiquitous computing devices has provided the catalyst for the next generation World Wide Web, one that shifts the focus from the desktop computer to mobile devices such as cell phones and PDAs, in an ever increasing range of modalities. Web interaction management in this setting must contend with a plethora of interaction interfaces and a diverse range of content types in addition to helping realize the full potential of multimodality (i.e., supporting flexible and personalized interactions between humans and sites). This thesis presents WS://IM, a new software framework for web interaction management that is capable of supporting multimodal interactions. In addition to presenting a loosely bundled, factorized architecture that supports hyperlink interaction, WS://IM has the unique facilitation for out-of-turn interaction. Out-of-turn interaction is a novel technique that helps realize mixed-initiative interactions between humans and Web sites. Design methodology, implementation details, and exposition through three implemented case studies are provided. / Master of Science

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Geographies of sexualities started to develop within the Anglo-American academic context during the late 1980s. In the 1990s, propelled by the cultural turn, the swelling of post-structuralist and postmodern critiques, and a growing recognition of the limitations to scientific knowledge production and representation, geographers of sexualities introduced queer theory into human geography. Queer theory provided human geography with powerful tools for approaching not only straightforward spatialities of sexualities, but this new lens contributed to the development of human geographies as such. Currently, at least in the Anglo-Saxon geographical context, the field of geographies of sexualities is considered part of mainstream human geography. Therefore, the main goal of this thesis is to provide a few lines of reasoning for the development of geographies of sexualities in Czechia and Central Eastern Europe (CEE) and introduction of post-structuralist understandings, specifically queer theory. In contrast to other phenomena that may be locally exclusive or particular, human sexualities are everyplace, albeit quite variable and dependent on the context in which they "enter into language," become institutionalized, and are regulated. Geographers have been specifically insightful about the ways in which...

Esta pesquisa tem como objetivo analisar o período compreendido entre a metade do século XIX e o começo do século XX a fim de identificar que aspectos e componentes da estética e valores culturais japoneses teriam sido eventualmente integrados aos movimentos artísticos europeus e ao design de moda. O interesse ocidental pelo Oriente sempre existiu, porém, foi intensificado após a abertura dos portos japoneses em 1854, depois de mais de dois séculos em reclusão. O encontro entre duas culturas tão distintas causou grande entusiasmo na Europa, com diversos autores que defendem que esta aproximação influenciou o rumo das artes, do design e de outros diversos campos, resultando em um movimento estético denominado Japonismo. Desse modo, esta pesquisa de natureza qualitativa, na modalidade histórica, gerada a partir de estudos bibliográficos e estudo de campo em museus e exposições, pretende expor exemplos e tecer reflexões sobre a importância do intercâmbio cultural entre o Japão e a Europa do final do século XIX e início do século XX, mais especificamente nos campos da arte e da moda / The aim of this research is to study the period between mid-19th century and beginning of 20th century to identify which aesthetic and cultural values aspects and components would eventually have been integrated to European fashion design and art movements. The occidental interest towards the orient have always existed, although, it was intensified after the opening of Japanese ports on 1854, after more than two centuries of seclusion. The encounter of such different cultures triggered enthusiasm in Europe, and several authors suggest that this gathering led the way of art, design and many several fields, resulting in an aesthetic movement called Japonism. Therefore, this qualitative research, on history, generated from bibliographical and field study in museums and exhibits, intends to bring into thought the importance of cultural exchange between Japan and Europe on the end of 19th Century and beginning of 20th century, specifically on art and fashion

Stockholm County is a post-industrial Swedish region characterized by high levels of mobility and technologization as well as ethnic and religious diversity. Among its religious minorities exist various strands of charismatic Christianity, some of which originate from the Pentecostal revival of the early 20th century and some of which belong to more recent movements. The aim of this ethnographic study is to examine how affiliates of the multicultural charismatic Christian congregation New Life Church practice religiosity within the context of their personal daily lives, within the framework of the general congregation and in terms of their involvements with other religious organizations in the area of Stockholm. Beginning with the assumption that the practice of contemporary religiosity and the development of a religious identity are part of an ongoing process of habituation, the study describes how practitioners cultivate a form of charismatic piety characterized by certain embodied orientations, patterns of ritualization and narrative genres. To shed further light on this process, it draws upon a variety of theories concerning ritualization, embodiment, performance, narratives and materiality. Apart from this, the study also constitutes an attempt to explore and measure the impact on the practitioners’ religiosity of late modern developments such as urbanization, detraditionalization and global mobility as well as the growing absorption in consumerism, emotional intimacy and the unfolding of the “authentic” inner self. While pursuing these ends, the study also calls into question previous assumptions about charismatic Christianity in Sweden, most particularly the assumption that today’s practitioners remain inclined to be entirely faithful to one given institution and its system of beliefs and practices. Indeed this view is directly challenged herein by the finding that contemporary charismatics are far more inclined to eclectically appropriate elements and models of thoughts from various contexts of origin as well as to affiliate with and/or visit multiple Christian institutions.

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