Wide-bandgap (WBG) semiconductor materials such as silicon carbide (SiC) and gallium-nitride (GaN) allow higher voltage ratings, lower on-state voltage drops, higher switching frequencies, and higher maximum temperatures. All these advantages make them an attractive choice when high-power density and high-efficiency converters are targeted. Two different gate-driver designs for SiC power devices are presented. First, a dual-function gate-driver for a power module populated with SiC junction field-effect transistors that finds a trade-off between fast switching speeds and a low oscillative performance has been presented and experimentally verified. Second, a gate-driver for SiC metal-oxide semiconductor field-effect transistors with a short-circuit protection scheme that is able to protect the converter against short-circuit conditions without compromising the switching performance during normal operation is presented and experimentally validated. The benefits and issues of using parallel-connection as the design strategy for high-efficiency and high-power converters have been presented. In order to evaluate parallel connection, a 312 kVA three-phase SiC inverter with an efficiency of 99.3 % has been designed, built, and experimentally verified. If parallel connection is chosen as design direction, an undesired trade-off between reliability and efficiency is introduced. A reliability analysis has been performed, which has shown that the gate-source voltage stress determines the reliability of the entire system. Decreasing the positive gate-source voltage could increase the reliability without significantly affecting the efficiency. If high-temperature applications are considered, relatively little attention has been paid to passive components for harsh environments. This thesis also addresses high-temperature operation. The high-temperature performance of two different designs of inductors have been tested up to 600_C. Finally, a GaN power field-effect transistor was characterized down to cryogenic temperatures. An 85 % reduction of the on-state resistance was measured at −195_C. Finally, an experimental evaluation of a 1 kW singlephase inverter at low temperatures was performed. A 33 % reduction in losses compared to room temperature was achieved at rated power. / <p>QC 20160922</p>

Esta dissertação analisa alguns aspectos fonéticos e fonológicos das consoantes glotalizadas da língua Dâw. Argumenta-se a favor da proposta de que, na língua Dâw, a glotalização é uma propriedade segmental e distintiva, conforme descrito por Martins (2004), restrita à classe das consoantes soantes. Observa-se mais de uma forma fonética nas consoantes glotalizadas, que incluem, sobretudo, fonação rangeada e voz áspera (ESLING; HARRIS, 2003). Quando comparadas às consoantes simples equivalentes, as consoantes glotalizadas são, em geral, mais curtas, têm forma de onda dos ciclos glotais mais irregular, H1H2 menor e frequência fundamental mais alta (nos casos sem rangeado). Exceto pelos níveis de frequência fundamental, as propriedades acústicas dos segmentos vizinhos não são afetadas. A glotalização confina-se ou manifesta-se com maior intensidade nas partes das consoantes que se encontram mais distantes das vogais adjacentes, padrão que também foi notado em outras línguas do mundo (PLAUCHÉ et al., 1998). Verificou-se que o aumento de frequência fundamental causado pela glotalização não provoca restrições no sistema tonal da língua Dâw e que os níveis de frequência fundamental dos tons lexicais são priorizados. A confirmação fonética do processo de redução silábica descrito por Martins (2004) permite defender que a glotalização e a oclusiva glotal compartilham o mesmo traço ou se definem por gestos semelhantes, sobretudo porque a comparação das características de ambas e a avaliação das consoantes soantes vizinhas de oclusivas glotais reforçam a semelhança. Entretanto, não há dados suficientes para sustentar a proposta de Martins (2005) de que as consoantes glotalizadas da língua Dâw originaram-se simplesmente da incorporação de traços das oclusivas glotais pelas consoantes simples. Por fim, observou-se que as ocorrências das formas da glotalização se relacionam com a nasalidade dos segmentos e com o sexo e a faixa etária dos falantes. A relação entre nasalidade e forma da glotalização, assim como o padrão temporal das consoantes glotalizadas, talvez possam ser explicados por fatores aerodinâmicos ou perceptuais (GORDON; LADEFOGED, 2001). Entretanto, este estudo não pôde avançar na compreensão da motivação desses fatos. A relação entre sexo, faixa etária e forma da glotalização não indica mudança em curso e demanda uma pesquisa sociolinguística mais aprofundada. / This thesis analyses some phonetic and phonological aspects of the glottalized sonorants of Dâw language. It argues in favor of the proposal that characterizes glottalization in Dâw language as a contrastive and a segmental property restricted to the class of the sonorant consonants (MARTINS, 2004). It describes more than one phonetic form for the glottalized consonants, mainly including creaky voice and harsh voice (ESLING; HARRIS, 2003). In general, the glottalized consonants are shorter, their glottal cycles have a more irregular waveform, they have smaller H1H2 and higher fundamental frequency (when creaky voice is absent) than the correspondent plain consonants. Except for the fundamental frequency levels, glottalization does not affect the acoustic properties of the neighbor segments. Glottalization is limited to or appears more noticeably in the parts of the consonants that are found at a greater distance from the neighbor vowels, a pattern that was also found in other languages (PLAUCHÉ et al., 1998). It was found that the increase in the fundamental frequency caused by glottalization does not restrict the tonal system in Dâw and the fundamental frequency levels of the lexical tones are prioritized. The phonetic confirmation of the process of syllable reduction described by Martins (2004) allows us to defend that glottalization and the glottal stop share the same feature or are defined by similar gestures, especially because the similarity is reinforced by the phonetic comparison between both phonemic entities and by the evaluation of the sonorant consonants in the neighborhood of the glottal stops. However, there is not sufficient information to sustain the proposal of Martins (2005) that the glottalized consonants in Dâw were originated merely from the incorporation of the glottal stop features by the plain consonants. Finally, this thesis notes that the occurrences of the glottalization types relate with the nasalization of the segments and the sex and the age group of the speakers. The relation between nasalization and glottalization type, as well as the glottalization timing, perhaps can be explained by aerodynamic and perceptual factors (GORDON; LADEFOGED, 2001). Nevertheless, this study was not able to deepen the understanding of the reasons for the aforementioned facts. The relation between sex, age group and glottalization type does not imply an ongoing change and demands further sociolinguistic research.

Esta dissertação analisa alguns aspectos fonéticos e fonológicos das consoantes glotalizadas da língua Dâw. Argumenta-se a favor da proposta de que, na língua Dâw, a glotalização é uma propriedade segmental e distintiva, conforme descrito por Martins (2004), restrita à classe das consoantes soantes. Observa-se mais de uma forma fonética nas consoantes glotalizadas, que incluem, sobretudo, fonação rangeada e voz áspera (ESLING; HARRIS, 2003). Quando comparadas às consoantes simples equivalentes, as consoantes glotalizadas são, em geral, mais curtas, têm forma de onda dos ciclos glotais mais irregular, H1H2 menor e frequência fundamental mais alta (nos casos sem rangeado). Exceto pelos níveis de frequência fundamental, as propriedades acústicas dos segmentos vizinhos não são afetadas. A glotalização confina-se ou manifesta-se com maior intensidade nas partes das consoantes que se encontram mais distantes das vogais adjacentes, padrão que também foi notado em outras línguas do mundo (PLAUCHÉ et al., 1998). Verificou-se que o aumento de frequência fundamental causado pela glotalização não provoca restrições no sistema tonal da língua Dâw e que os níveis de frequência fundamental dos tons lexicais são priorizados. A confirmação fonética do processo de redução silábica descrito por Martins (2004) permite defender que a glotalização e a oclusiva glotal compartilham o mesmo traço ou se definem por gestos semelhantes, sobretudo porque a comparação das características de ambas e a avaliação das consoantes soantes vizinhas de oclusivas glotais reforçam a semelhança. Entretanto, não há dados suficientes para sustentar a proposta de Martins (2005) de que as consoantes glotalizadas da língua Dâw originaram-se simplesmente da incorporação de traços das oclusivas glotais pelas consoantes simples. Por fim, observou-se que as ocorrências das formas da glotalização se relacionam com a nasalidade dos segmentos e com o sexo e a faixa etária dos falantes. A relação entre nasalidade e forma da glotalização, assim como o padrão temporal das consoantes glotalizadas, talvez possam ser explicados por fatores aerodinâmicos ou perceptuais (GORDON; LADEFOGED, 2001). Entretanto, este estudo não pôde avançar na compreensão da motivação desses fatos. A relação entre sexo, faixa etária e forma da glotalização não indica mudança em curso e demanda uma pesquisa sociolinguística mais aprofundada. / This thesis analyses some phonetic and phonological aspects of the glottalized sonorants of Dâw language. It argues in favor of the proposal that characterizes glottalization in Dâw language as a contrastive and a segmental property restricted to the class of the sonorant consonants (MARTINS, 2004). It describes more than one phonetic form for the glottalized consonants, mainly including creaky voice and harsh voice (ESLING; HARRIS, 2003). In general, the glottalized consonants are shorter, their glottal cycles have a more irregular waveform, they have smaller H1H2 and higher fundamental frequency (when creaky voice is absent) than the correspondent plain consonants. Except for the fundamental frequency levels, glottalization does not affect the acoustic properties of the neighbor segments. Glottalization is limited to or appears more noticeably in the parts of the consonants that are found at a greater distance from the neighbor vowels, a pattern that was also found in other languages (PLAUCHÉ et al., 1998). It was found that the increase in the fundamental frequency caused by glottalization does not restrict the tonal system in Dâw and the fundamental frequency levels of the lexical tones are prioritized. The phonetic confirmation of the process of syllable reduction described by Martins (2004) allows us to defend that glottalization and the glottal stop share the same feature or are defined by similar gestures, especially because the similarity is reinforced by the phonetic comparison between both phonemic entities and by the evaluation of the sonorant consonants in the neighborhood of the glottal stops. However, there is not sufficient information to sustain the proposal of Martins (2005) that the glottalized consonants in Dâw were originated merely from the incorporation of the glottal stop features by the plain consonants. Finally, this thesis notes that the occurrences of the glottalization types relate with the nasalization of the segments and the sex and the age group of the speakers. The relation between nasalization and glottalization type, as well as the glottalization timing, perhaps can be explained by aerodynamic and perceptual factors (GORDON; LADEFOGED, 2001). Nevertheless, this study was not able to deepen the understanding of the reasons for the aforementioned facts. The relation between sex, age group and glottalization type does not imply an ongoing change and demands further sociolinguistic research.

Growing need for application of electronics at temperatures beyond their rated limit, (usually > 150 °C) and the non availability of high temperature compatible electronics necessitates thermal management solutions that should be compact, scalable, reliable and be able to work in environments characterized by high temperature (150 -250 °C), mechanical shock and vibrations. In this backdrop the proposed research aims at realization of an adsorption cooling system for evaporator temperatures in the range of 140 °C-150 °C, and condenser temperature in the range of 160 °C-200 °C. Adsorption cooling systems have few moving parts (hence less maintenance issues), and the use of Thermo-Electric (TE) devices to regenerate heat of adsorption in between adsorbent beds enhances the compactness and efficiency of the overall 'ThermoElectric-Adsorption' (TEA) system. The work presented identifies the challenges involved and respective solutions for high temperature application. An experimental set up was fabricated to demonstrate system operation and mathematical models developed to benchmark experimental results. Also, it should be noted that TEA system comprises TE and adsorption chillers. A TE device can be a compact cooler in its own right. Hence a comparison of the performance of TEA and TE cooling systems has also been presented.

<p>This master thesis is about investigation a power efficient anti-moisture device thatcan be implemented in electronic enclosures in severe climatic environments.First, some of the existing knowledge and previous works were introduced. Then arelevant theoretical background including three main approaches in humiditymanagement are described, comparison between the enclosure heaters and localheaters, some psychrometics concepts that have been used in the project, heattransfer fundamentals, environmental test basics, some humidity and temperaturesensing techniques, computational fluid dynamics, programmable logic controlfundamentals, comparison PLCs with microcontrollers was provided.A series experiments have been performed in order to find the power efficient andmost effective anti-moisture method. Based on the analysis of the experiment data,the local heater system has been designed. CFD assisted parametric study of thelocal heater has been performed in order to find the best feasible design includingthe size and location. The local heater has been built based on the results ofparametric study. Different materials have been tested in laboratory in order tofind the proper material for final prototype of heater. The implemented localheater has been integrated with programmable logic control device. The controlalgorithm has been developed for activation/deactivation of local heater. The logiccontrolled PCB local heater has been experimentally evaluated.In the end the results achieved from environmental test have been presented andanalyzed. Some conclusions on the results and also future work have been discussed.</p>

There is often an assumption that there is a right and a wrong way for consumers to behave. For example, with regard to eating, people should make food choices based on maximizing vitamins and minerals and not consuming more calories than one expends in a day. Likewise, it is assumed that buying products to conspicuously signal a message to another is wasteful and maladaptive. The research in this thesis challenges these assumptions and argues that these behaviours can be both adaptive and maladaptive depending on one’s environmental conditions. In this thesis, I describe three experiments that examine how perception of environmental harshness affects appetite for different types of foods. The data shows that food desirability in adulthood varies depending on early childhood socio-economic status, the type of environmental stressor (harsh social, harsh economic and harsh physical safety) and the intensity of the stressors within each of these environments. It was also found that different types of environmental harshness differentially affects food desire based on energy density and food category type. In addition to the experiments on harshness and food desirability, I have examined how environmental harshness affects desire for products that are used to conspicuously signal information to others. For example, under conditions of environmental stress, products may be used to advertise that a male possesses financial or physical power which is desirable to a potential mate. Likewise, a women may buy products to display she possess financial power or she may purchase products that augment her beauty and sexual attractiveness. These studies reveal that product desire is also affected by different types of environmental harshness and the intensity of the stress generated by these environmental conditions. Through the research described in this thesis, we gain a more comprehensive understanding of the proximate variables that influence two subsets of consumer behaviour, namely food desire and product signalling, and how these behaviours may have been selected for due to their adaptive value.

La Thèse a été réalisée en cotutelle entre l’Université Jean Monnet de Saint Etienne (France) et l’université de Palerme (Italie) et en collaboration avec l’Agence nationale pour la gestion des déchets radioactifs (ANDRA). Le travail de recherche concerne l'étude des capteurs répartis à fibres optiques (utilisant la lumière rétrodiffusée Raman et Brillouin) destinés à l’observation et à la surveillance des ouvrages dédiés au stockage géologique de déchets radioactifs de haute activité et moyenne activité à vie longue (projet CIGEO : centre industriel de stockage géologique). Dans ce contexte, les fibres optiques sont envisagées en tant qu’élément sensible de capteurs pour la mesure de paramètres environnementaux tels que la température ou la déformation. Les conditions environnementales extrêmes d’exploitation entrainent la dégradation des propriétés de la fibre optique et des performances du capteur. La réponse des capteurs Brillouin et Raman est influencée par la présence de rayonnement y et d’hydrogène dans l’atmosphère Cigéo. Dans les deux cas, une diminution de la transmission linéique de la fibre optique est observée. Ce phénomène est dû à l’atténuation induite par radiation (RIA) ou par hydrogène (HIA) réduisant ainsi la portée de la mesure. En outre le rayonnement y et l’hydrogène provoquent des erreurs sur la mesure de température ou de déformation pour les deux types de capteurs. L’étude a permis d’établir les lignes directrices pour la sélection et le développement des capteurs repartis à fibre optique appropriés pour travailler dans l’environnement Cigéo / This PhD thesis is conducted in the joint supervision of both the University Jean Monnet of Saint Etienne (France) and the University of Palermo (Italy) in collaboration with the French national agency for the management of radioactive wastes (ANDRA). The aim of the Thesis is to evaluate the performances of distributed optical fiber sensors (based on Raman and Brillouin scattering technologies) that will be employed for monitoring industrial site for deep geological disposal for high and long-lived intermediate level activity radioactive waste (HL-W and LL/IL-W, respectively), called Cigéo. In this context, the distributed optical fiber sensors will provide a time and spatial cartography of the strain and temperature inside the disposal cell. The severe environment of Cigéo requires the sensor evaluation taking into account the resulting degradation of the sensing optical fiber. The sensor response is affected by y-rays and hydrogen presences inside the storage cells. In both cases a decrease of the optical fiber transmission, due to the radiation or hydrogen induced attenuation (RIA or HIA) is observed and limits the sensing distance range of the sensor. Moreover, the two different environment constraints lead to errors in the temperature or strain evaluation for both sensor technologies. This Thesis work establishes the guidelines to select and design distributed optical fiber sensors suitable to operate in radiation environment such as Cigéo one

Since the 1990s water quality monitoring projects using aquatic insects or macroinvertebrates as bioindication in Mongolia has mostly occurred in rivers drainage to the Arctic Ocean. They have been conducted to identify different anthropogentic stressors and impacts upon these running water ecosystems. However, there are still knowledge gaps and uncertainties concerning the research of these macroinvertebrates, in particular, a life cycle study of representative species are one such section of information missing. The specific aim for the study was to determine their life cycles and secondary production of selected species in the Kharaa River Basin, Mongolia, where these animals are exposed to harsh environment conditions. The main challenges for the research project were selecting the most suitable methods for use in the field sampling campaigns as well as establishing biomonitoring criteria for the target species under the extreme harsh climatic conditions. The research also sorts to address the pre-existing taxonomical identification problems. Consequently, a multi-habitat quantitative sampling method, and emergence traps type ‘Model week’ were selected. Five specific traits were chosen as selection criteria from the literature, where the life cycles of numerous species were investigated under comparable conditions to this study. Based on those five distinct criteria, a total of 18 species from EPT group (Ephemeroptera, Plecoptera, and Trichoptera) were selected for deeper analysis. This thesis provided the first quantitative results on the life cycle, production, growth rate and emergence of aquatic insects from Mongolia, to allow comparisons with studies in other regions using the same methods. However, it still needs more quantitative research of population dynamics for a wider range of species including fecundity, accurate development rates, mortality losses (e.g., due to predation), and food availability across environmental gradients of hydraulic conditions and substrate types. In conclusion, last not least it is essential to obtain knowledge especially about life cycle strategies of macroinvertebrates to identify the indicator-properties of single species and to predict re-colonisation potential of disturbed habitats and to evaluate the efficiency of management measures.

No description available.

Low-power wireless networks consist of spatially distributed, resource-constrained devices – also referred to as nodes – that are typically equipped with integrated or external sensors and actuators. Nodes communicate with each other using wireless transceivers, and thus, relay data – e. g., collected sensor values or commands for actuators – cooperatively through the network. This way, low-power wireless networks can support a plethora of different applications, including, e. g., monitoring the air quality in urban areas or controlling the heating, ventilation and cooling of large buildings. The use of wireless communication in such monitoring and actuating applications allows for a higher flexibility and ease of deployment – and thus, overall lower costs – compared to wired solutions. However, wireless communication is notoriously error-prone. Message losses happen often and unpredictably, making it challenging to support applications requiring both high reliability and low latency. Highly reliable, low-latency communication – along with high energy-efficiency – are, however, key requirements to support several important application scenarios and most notably the open-/closed-loop control functions found in e. g., industry and factory automation applications. Communication protocols that rely on synchronous transmissions have been shown to be able to overcome this limitation. These protocols depart from traditional single-link transmissions and do not attempt to avoid concurrent transmissions from different nodes to prevent collisions. On the contrary, they make nodes send the same message at the same time over several paths. Phenomena like constructive interference and capture then ensure that messages are received correctly with high probability. While many approaches relying on synchronous transmissions have been presented in the literature, two important aspects received only little consideration: (i) reliable operation in harsh environments and (ii) support for event-based data traffic. This thesis addresses these two open challenges and proposes novel communication protocols to overcome them.