Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 155-168). Also available in electronic version.

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The development of monolithic microwave integrated circuits (MMICs) has enabled the expansion of multiple circuit elements on a single piece of semiconductor, enclosed in a package with connecting leads. Attributable to the widespread use of wireless circuits and sub-systems, MMICs meet stringent demands for smaller chip area, low loss and low cost. These require highly integrated MMICs with compact features. This thesis provides valuable insight into the design of compact multifunctional MMICs using three-dimensional (3-D) multilayer technology. The proposed technology offers compact, hence low-cost solutions, where all active and passive components are fabricated vertically on the same substrate and no expensive via hole or backside processing is required. The substrate used in this work contains pre-fabricated 0.5 µm pseudomorphic High Electron Mobility Transistor (pHEMT) GaAs active devices. The performances of the uncommitted and committed pHEMTs are compared in terms of their DC, small-signal and large-signal RF measurements and modelling results. Committed pHEMT refers to the pHEMT that is connected to multilayer circuit, whereas uncommitted pHEMT is not. The effect of integrating committed pHEMTs with multilayer passive components is studied and the suitability of the multilayer fabrication processing is assessed. Using this technology, two pHEMT Schottky diodes with 120 µm and 200 µm gate widths are designed, fabricated and extensively characterised by I-V, C-V and S-parameter measurements. The information gained from the measurements is then used to extract all unknown equivalent circuit model parameters using high-frequency on-wafer microwave probing. The measured results showed good agreement with the modelled ones over the frequency range up to 40 GHz. Preliminary demonstrations of the use of these pHEMT Schottky diodes in microwave limiter and detector circuit applications are also discussed, showing promising results. Finally, the implementation of 3-D multilayer technology is shown for the first time in single-pole single-throw (SPST) and single-pole double-throw (SPDT) switches design by utilising the pre-fabricated pHEMTs. The design and analysis of the switches are demonstrated first through simulation using TriQuint's Own Model - Level 3 (TOM3). Three optimised SPST and SPDT pHEMT switching circuits which can address applications ranging from L to X bands are successfully fabricated and tested. The performance of the pHEMT switches is comparable to those of the current state-of-the-art, while simultaneously offering compact circuits with the advantages of integration with other MMIC components. All works reported in this thesis should facilitate foundry design engineers towards further development of 3-D multilayer technology.

O presente estudo tem como objetivo identificar os papéis na compra de interruptores de luz por clientes finais e identificar as influências desses papéis e como ocorrem. O método utilizado foi dividido em duas fases, a primeira com abordagem qualitativa e a segunda com abordagem quantitativa. Inicialmente foram feitas entrevistas em profundidade com consumidores e profissionais da área, com o objetivo de identificar quais os tipos de papéis que ocorrem durante a compra de interruptores e identificar os influenciadores. O segundo passo foi uma survey, sendo entrevistadas 1.013 pessoas divididas nas cinco regiões do país, Região Centro Oeste, Nordeste, Sul, Norte e Sudeste. Foram identificados cinco papéis de compra e sete influenciadores desse processo. Os resultados da pesquisa quantitativa foram analisados com análises univariadas e multivariadas. As análises indicam que os compradores adquirem interruptores para outros usuários, mas a grande maioria deles adquirem o produto para uso próprio e são responsáveis pela compra e pelo pagamento do produto. Os resultados também indicam que as pessoas próximas são os maiores influenciadores. Espera-se que com os resultados obtidos esse trabalho possa contribuir para executivos e empresas do setor elétrico na tomada de decisões. / The present paper has the objective to identify which are the final consumers purchase roles of light switches and identify the influences about this roles and how it occurs. The analysis method was dividing in two steps, the first with a qualitative approach and the second with a quantitative approach. First of all, had been made depth interviews with consumers and professionals from the area, with the objective to identify the influencers. After that, a survey has been made, 1.013 people were interviewed and divided at five regions of the country, Midwest region, Northeast, South, North and Southeast. Were identified five purchase roles and seven influencers of this process. The quantitative research results were analyzed with univariate and multivariate analysis. The analysis indicate that the buyers also buy the light switches for other users, but the majority buy the product for own use and is responsible for the purchase and the product payment. The results also indicate that, in general, close people are the major influencers. With the obtained results throw crossing and the performed analyses, the expectations with this paper is contribute with executives and companies of the area on theirs decision-making.

O presente estudo tem como objetivo identificar os papéis na compra de interruptores de luz por clientes finais e identificar as influências desses papéis e como ocorrem. O método utilizado foi dividido em duas fases, a primeira com abordagem qualitativa e a segunda com abordagem quantitativa. Inicialmente foram feitas entrevistas em profundidade com consumidores e profissionais da área, com o objetivo de identificar quais os tipos de papéis que ocorrem durante a compra de interruptores e identificar os influenciadores. O segundo passo foi uma survey, sendo entrevistadas 1.013 pessoas divididas nas cinco regiões do país, Região Centro Oeste, Nordeste, Sul, Norte e Sudeste. Foram identificados cinco papéis de compra e sete influenciadores desse processo. Os resultados da pesquisa quantitativa foram analisados com análises univariadas e multivariadas. As análises indicam que os compradores adquirem interruptores para outros usuários, mas a grande maioria deles adquirem o produto para uso próprio e são responsáveis pela compra e pelo pagamento do produto. Os resultados também indicam que as pessoas próximas são os maiores influenciadores. Espera-se que com os resultados obtidos esse trabalho possa contribuir para executivos e empresas do setor elétrico na tomada de decisões. / The present paper has the objective to identify which are the final consumers purchase roles of light switches and identify the influences about this roles and how it occurs. The analysis method was dividing in two steps, the first with a qualitative approach and the second with a quantitative approach. First of all, had been made depth interviews with consumers and professionals from the area, with the objective to identify the influencers. After that, a survey has been made, 1.013 people were interviewed and divided at five regions of the country, Midwest region, Northeast, South, North and Southeast. Were identified five purchase roles and seven influencers of this process. The quantitative research results were analyzed with univariate and multivariate analysis. The analysis indicate that the buyers also buy the light switches for other users, but the majority buy the product for own use and is responsible for the purchase and the product payment. The results also indicate that, in general, close people are the major influencers. With the obtained results throw crossing and the performed analyses, the expectations with this paper is contribute with executives and companies of the area on theirs decision-making.

Made available in DSpace on 2014-06-12T15:58:06Z (GMT). No. of bitstreams: 2 arquivo3252_1.pdf: 2382561 bytes, checksum: c2a06bbc48d03850db39ab0f6ef2859e (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2011 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Este trabalho apresenta uma proposta para gerenciamento e monitoramento de redes virtuais através da adaptação do Nagios, uma ferramenta de gerência e monitoramento amplamente utilizada em datacenters por administradores de rede. Esta adaptação foi implementada através da criação de um plug-in que coleta dados relevantes de switches virtuais realizando inferências de estados de disponibilidade destes switches. Para verificação da usabilidade do plug-in, foi criada uma rede virtual utilizando o software de padrão aberto Openflow e OpenvSwitch em conjunto com o NOX, além da criação de máquinas virtuais sobre o virtualizador KVM com o auxílio da biblioteca libvirt para criação das máquinas virtuais e interfaces virtuais

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Cette thèse propose un schéma entièrement distribué de routage résilient pour les réseaux de switches. Dans cette approche une panne est traitée localement ; ainsi les autres nœuds du réseau n’ont pas besoin de prendre des mesures spécifiques. Contrairement aux systèmes classiques de routage IP qui se base uniquement sur la destination, le routage est fait en se basant sur l’arc de l’entrée et la destination. La contrainte qui en résulte est que les deux flux à la même destination entrant dans un nœud par un arc commun doivent fusionner après cet arc. Nous montrons que sous des faibles hypothèses (en supposant que le réseau est symétrique et bi-connexes au sens des liens), il existe un schéma de routage résilient pour toutes les situations de pannes simples de liens. Nous modélisons le problème de dimensionnement par un programme linéaire en nombres entiers qui peut être résolu exactement pour des réseaux de taille modeste. Nous proposons également plusieurs heuristiques pour traiter des instances de grande taille. Notre méthode généralise les méthodes de la littérature, en particulier celles de Xi et al. et de Nelakuditi et al. qui ont proposé des approches similaires. Notre approche permet d’obtenir de meilleurs résultats sur de nombreuses instances de test. Nous avons également étudié l’existence d’un schéma de routage résilient pour situation de panne de nœud dans le réseau basée sur les switches. Nous montrons que dans le cas des pannes de plusieurs liens, la condition de connexité n’est pas suffisante. / This thesis presents a fully distributed resilient routing scheme for switch-based networks. A failure is treated locally, so other nodes in the network do not need to undertakespecial actions. In contrast to conventional IP routing schemes, each node routesthe traffic on the basis of the entering arc and of the destination. The resulting constraintis that two flows to the same destination entering in a node by a common archave to merge after this arc. We show that this is sufficient for dealing with all singlelink failure situations, assuming that the network is symmetric and two-link connected.We model the dimensioning problem with an Integer Linear Program which can besolved exactly for small networks. We also propose several heuristics for larger networks.Our method generalizes the methods of Xi et Chao and Li and of Nelakuditiet al. who have proposed similar schemes in the context of IP. Our methods are moreefficient than previous ones. We have also studied the existence of a resilient routingscheme for single node failure situation in switch-based network. We study also thecase of multi-link failure situations and show that requiring the network to be connectedafter any failure does not guarantee the existence of a resilent routing schemeas described above.

The current temperature operating range of semiconducting materials is given to be between -10°C and 105°C. Current plans are to increase this range due to an industry demand for semiconducting materials able to operate outside these bounds. Wide bandgap semiconductor materials have been researched for some time in an effort to manufacture commercially viable controlled semiconductor switches. Samples of such a controlled switch have been obtained and promises to be close to commercial rollout. This controlled switch takes on the form of a Junction Field Effect Transistor (JFET), which is a depletion mode component. Depletion mode switches are normally-on, and have thus far not been used in the power electronics field. Due to difficult switching and availibility of component which are switched more easily, these components were quicklier and easierly adopted for use. The Silicon Carbide JFET promises to circumvent these cons with the ability to block higher voltages, at higher temperatures and at higher speeds. Lower on resistance and smaller size of substrates are other benefits that the use of Silicon Carbide semiconducting material promises. A variety of properties of the Silicon Carbide JFET are investigated. Some of these properties include the component on-resistance, gate charge, breakthrough voltage of the gate and leakage current of the channel. Switching performance is also investigated as well as the reverse recovery of the body diode. All properties were measured as a function of temperature in an effort to describe the difference in performance at high temperatures. / Prof. Ivan Hofsajer

The IEEE Standard for Gigabit Networking was accepted in June 1998 and ratified as IEEE 802.3z. This standard uses considers an optical cable for signal transmission. One year later a new standard for Gigabit Ethernet over unshielded twisted pair of the 5th category was certified under the name 802.3ab. Nowadays, there are a couple of younger and older studies about Gigabit Ethernet technology and performance. This Meta Analysis is intended to put the main results altogether into one document suitable for a proper choice of gigabit networking equipment for cluster computers.