Made available in DSpace on 2015-05-14T12:13:59Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 283471 bytes, checksum: 3c03d229984755f09c77c7e98c3f465e (MD5) Previous issue date: 2011-06-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work we present a quantum description of a mesoscopic RLC circuit without source. For this purpose, we model this system for that of a damped harmonic oscillator which is described by the Caldirola-Kanai Hamiltonian. Then, with the aid of the quantum invariant method we solve the Schrödinger equation associated with this Hamiltonian and write the corresponding wave functions in terms of a particular solution of the Milne-Pinney equation. We also construct coherent states for the RLC quantized, and evaluate the quantum fluctuations of the charge and the magnetic flux, as well as the corresponding product of uncertainty. / Nesta dissertação, apresentamos uma descrição quântica de um circuito RLC mesoscópico sem fonte. Com esta finalidade, modelamos este sistema para aquele de um oscilador harmônico amortecido, que é descrito pelo Hamiltoniano de Caldirola-Kanai. Então, com a ajuda do método de invariantes quânticos, resolvemos a equação de Schrödinger para este Hamiltoniano e escrevemos as funções de onda correspondentes em termos da solução particular da equação de Milne-Pinney. Também construímos estados coerentes para o circuito RLC quantizado, e calculamos as flutuações quânticas da carga e do fluxo magnético, bem como o produto de incerteza correspondente.

4G LTE is a new cellular phone network standard to provide both the capacity and Quality of Service (QoS) needed to support multimedia applications. Recent research in LTE has explored modifications to the current QoS setup, creating MAC layer schedulers and modifying the current QoS architecture. However, what has not been fully explored are the effects of LTE retransmission choices and capabilities on QoS. This thesis examines the impact of using acknowledgments to recover lost data over the wireless interface on VoIP, FTP and MPEG video applications. Issues explored include interaction between application performance, network transport protocols, LTE acknowledgment mode, and wireless conditions. Simulations show that LTE retransmissions improve FTP throughput by 0.1 to 0.8 Mb/s. With delay sensitive applications, like VoIP and video, the benefits of retransmissions are dependent on the loss rate. When the wireless loss rate is less than 20%, VoIP has similar performance with and without LTE retransmissions. At higher loss rates the use of LTE retransmissions adds degrading the VoIP quality by 71%. With UDP video, the choice of retransmissions or not makes little change when the wireless loss rates are less than 10%. With higher wireless loss rates, the frame arrival delay increases by up to 539% with LTE retransmissions, but the frame rate of the video decreases by up to 34% without those retransmissions. LTE providers should configure their networks to use retransmission policies appro- priate for the type of application traffic. This thesis shows that VoIP, FTP and video require different configurations in the LTE network layers.

Made available in DSpace on 2015-05-14T12:14:17Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 686892 bytes, checksum: cec59fce2ac377aef923c62e1cac0207 (MD5) Previous issue date: 2014-06-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / We present an alternative quantum treatment for a generalized mesoscopic RLC circuit with time-dependent resistance, inductance and capacitance. Taking advantage of the Lewis and Riesenfeld and quadratic invariants we obtain exact nonstationary Schrödinger states for this electromagnetic oscillation system. Afterwards, we construct coherent states for the quantized RLC circuit and employ them to investigate some of the system s quantum properties, such as quantum fluctuations of the charge and the magnetic flux and the corresponding uncertainty product. In addition, we derive the geometric, dynamical and Berry phases for this nonstationary mesoscopic circuit. Finally we evaluate the dynamical and Berry phases for three special circuits. Surprisingly, we find identical expressions for the dynamical phase and the same formulae for the Berry s phase. / Apresentamos um tratamento quântico alternativo para um circuito RLC mesoscópico generalizado com resistência, indutância e capacitância dependentes do tempo. Usando o método de invariantes quânticos de Lewis e Riesenfeld e invariantes quadráticos, obtemos os estados de Scrhödinger não-estacionários para este circuito com oscilação eletromagnética. Em seguida, construímos os estados coerentes para o circuito RLC quantizado e os empregamos para investigar algumas das propriedades quânticas do sistema, tais como flutuações quânticas da carga, do fluxo magnético e o produto incerteza correspondente. Além disso, obtemos as fases geométricas, dinâmicas e de Berry para este circuito mesoscópico não estacionário. Finalmente, calculamos as fases dinâmica e de Berry para três casos particulares. Surpreendentemente, encontramos expressões idênticas para a fase dinâmica, e as mesmas expressões para a fase da Berry.

Au cours de ces dernières années, les communications sans fil connaissent une croissance vertigineuse, avec le développement de standards de communication de plus en plus nombreux, qui ouvrent la voie à de multiples applications telles que : la téléphonie mobile, le biomédical, le maritime, le civil et le militaire. De nos jours, les communications sans fil se sont diversifiées et multipliées. Cela entraîne la conception d’antennes toujours plus innovantes, performantes et de taille de plus en plus réduite (miniaturisation). Le projet FLEXBEA (FLEXible BEAcon) a pour but le développement d’un nouveau concept de balises de détresse miniatures (AIS et COSPAS-SARSAT), faible coût, intégrées dans des équipements de sécurité maritime tels qu’un radeau de survie et un gilet de sauvetage. Ces équipements sont destinés aux professionnels de la mer et aux plaisanciers. L’atout majeur de ce nouveau concept est l’intégration dans des équipements de sécurité maritime d’une fonction de détresse en cas de problème majeur : homme à la mer (MOB, Man OverBoard) par exemple lors d’un naufrage. Différentes antennes ont été étudiées. Nous présentons des antennes planaires (de type dipôle ou monopôle imprimé) développées dans la bande UHF : une solution de dipôle avec brins repliés est proposée afin de réduire l'encombrement, et deux modes d'alimentation (symétrique / dissymétrique) sont comparés. Des exemples d'antenne monopôle sont ensuite présentés avec une modification de leur géométrie (structures de type Bow-tie ou méandre) pour assurer une miniaturisation optimale. Puis les antennes filaires retenues pour le projet, avec une modélisation de ces antennes par un circuit équivalent (RLC). Des formules analytiques sont proposées afin de déterminer les valeurs de composants RLC qui interviennent dans le modèle circuit. Ensuite, nous sommes passés à la conception de l’antenne de la balise. Deux antennes ont été conçues et mesurées. Un monopôle ruban avec introduction de composants localisés pour la balise AIS et COSPAS-SARSAT, et une antenne hélice fonctionnant dans la bande AIS, intégrée dans la balise "SIMY". De nombreuses réalisations et mesures ont été effectuées pour caractériser ses antennes. / Over the last few years, wireless communications have grown dramatically, with the development of more and more communication standards, which open the way to multiple applications such as: mobile telephony, biomedical, maritime, the civilian and the military. Today, wireless communications have diversified and multiplied. This leads to the design of antennas that are always more innovative, more efficient and smaller in size (miniaturization). The FLEXBEA project (FLEXible BEAcon) aims to develop a new concept of low cost miniature distress beacons (AIS and COSPAS-SARSAT) integrated into marine safety equipment such as a life raft and a lifejacket safety. This equipment is intended for professionals of the sea and boaters. The main advantage of this new concept is the integration in maritime safety equipment of a distress function in case of major problem: man overboard (MOB, Man OverBoard) for example during a shipwreck. Different antennas have been studied. We present planar antennas (dipole type or printed monopoly) developed in the UHF band: a dipole solution with folded strands is proposed to reduce the bulk, and two modes of supply (symmetrical / asymmetrical) are compared. Examples of monopole antennas are then presented with a modification of their geometry (Bow-tie or meander type structures) to ensure optimal miniaturization. Then the wired antennas selected for the project, with a modeling of these antennas by an equivalent circuit (RLC). Analytical formulas are proposed to determine the RLC component values ​​involved in the circuit model. Then we went to the design of the beacon antenna. Two antennas were designed and measured. A ribbon monopoly with introduction of localized components for the AIS and COSPAS-SARSAT beacon, and a helix antenna operating in the AIS band, integrated into the "SIMY" beacon. Many achievements and measurements have been made to characterize its antennas.

The fracture of brittle materials is of utmost importance for civil engineering and seismology applications. A different approach towards the aim of early identification of fracture and the prediction of failure before it occurs is attempted in this work. Laboratory experiments were conducted in a variety of rock and cement based material specimens of various shapes and sizes. The applied loading schemes were cyclic or increasing and the specimens were tested to compression and bending type loading of various levels. The techniques of Pressure Stimulated Current and Bending Stimulated Current were used for the detection of electric signal emissions during the various deformation stages of the specimens. The detected signals were analysed macroscopically and microscopically so as to find suitable criteria for fracture prediction and correlation between the electrical and mechanical parameters. The macroscopic proportionality of the mechanically stimulated electric signal and the strain was experimentally verified, the macroscopic trends of the PSC and BSC electric signals were modelled and the effects of material memory to the electric signals were examined. The current of a time-varying RLC electric circuit was tested against experimental data with satisfactory results and it was proposed as an electrical equivalent model. Wavelet based analysis of the signal revealed the correlation between the frequency components of the electric signal and the deformation stages of the material samples. Especially the increase of the high frequency component of the electric signal seems to be a good precursor of macrocracking initiation point. The additional electric stimulus of a dc voltage application seems to boost the frequency content of the signal and reveals better the stages of cracking process. The microscopic analysis method is scale-free and thus it can confront with the problems of size effects and material properties effects. The AC conductivity time series of fractured and pristine specimens were also analysed by means of wavelet transform and the spectral analysis was used to differentiate between the specimens. A non-destructive technique may be based on these results. Analysis has shown that the electric signal perturbation is an indicator of the forthcoming fracture, as well as of the fracture that has already occurred in specimens.

<p>The Internet has mainly been interconnecting stationary computers by wired links, but an increasing number of mobile clients require wireless communication. One way to connect these clients is to use the Universal Mobile Telecommunication System, UMTS. UMTS is a third generation mobile system. </p><p>A network can be seen as nodes interconnected by links. The functionality of the nodes can be described as a layered hierarchy. A reference model for this hierarchy was developed by OSI. In this model the second lowest layer is called data link layer. The data link layer is responsible for making the raw transmission appear error free to upper layers. </p><p>The focus for this thesis is the data link layer in the UMTS. Compared to the data link layer in a wired scenario it contains more control and error correction mechanisms. These mechanisms use a lot of timers and triggers, which makes it very difficult to analyze them mathematically. Therefore simulation is the preferred method. </p><p>For the simulations the network simulator version 2 was used. This is an open source discrete event simulator. It has a modularized wireless stack already implemented. This can not be used to simulate UMTS though. Some modules in this stack were replaced by a new implementation to make simulations on UMTS possible. </p><p>Tests were performed on the new implementation and the results were what could be expected. The results were also consistent with previous research in the area.</p>

The Internet has mainly been interconnecting stationary computers by wired links, but an increasing number of mobile clients require wireless communication. One way to connect these clients is to use the Universal Mobile Telecommunication System, UMTS. UMTS is a third generation mobile system. A network can be seen as nodes interconnected by links. The functionality of the nodes can be described as a layered hierarchy. A reference model for this hierarchy was developed by OSI. In this model the second lowest layer is called data link layer. The data link layer is responsible for making the raw transmission appear error free to upper layers. The focus for this thesis is the data link layer in the UMTS. Compared to the data link layer in a wired scenario it contains more control and error correction mechanisms. These mechanisms use a lot of timers and triggers, which makes it very difficult to analyze them mathematically. Therefore simulation is the preferred method. For the simulations the network simulator version 2 was used. This is an open source discrete event simulator. It has a modularized wireless stack already implemented. This can not be used to simulate UMTS though. Some modules in this stack were replaced by a new implementation to make simulations on UMTS possible. Tests were performed on the new implementation and the results were what could be expected. The results were also consistent with previous research in the area.

3D design is being recognized widely as the next BIG thing in system integration. However, design and analysis tools for 3D are still in infancy stage. Power supply noise analysis is one of the critical aspects of a design. Hence, the area of noise analysis for 3D designs is a key area for future development. The following research presents a new parasitic RLC modeling technique for 3D chips containing TSVs as well as a novel optimization algorithm for power-ground network of a 3D chip with the aim of minimizing noise in the network. The following work also looks into an existing commercial IR drop analysis tool and presents a way to modify it with the aim of handling 3D designs containing TSVs.

Fusion neutrons from high energy density plasmas generated by pulsed laser irradiation of nanoscale atomic clusters have been explored in recent experiments at the University of Texas at Austin. A sufficiently strong (~200 T) magnetic field is expected to produce a magnetized, high temperature (10 keV) plasma with beta [approximately equal to] 1. Such a field along the laser axis may confine the plasma’s radial expansion, thus increasing fusion yield. As part of a multi-stage project to implement this experiment, a scaled (~40 T, ~500 KA) version of the final 200 T, 2.2 MA pulsed power device has been designed and built by Sandia National Laboratories and is now at UT-Austin. This apparatus, named MegaGauss, is meant to serve as a preparation tool for the 200 T system; as such, its current pulse was recorded for analysis, and is compared to a theoretical model to verify its response parameters (e.g. peak current, time to peak). Techniques and results of this comparison are discussed, followed by explanations of basic construction of the 40 T device and current sensing instrumentation. Discussion of MegaGauss is completed with a survey of notable failure modes, and a description of the often severe effects the miniature field-generating Helmholtz coil experiences due to the current pulse and magnetic field. Finally, a novel data archive scheme, structured around the familiar MDSplus archive system, is implemented in Labview and integrated into the main pulsed power control program. Specifically, methods for linking MDSplus’s robust functionality with Labview’s intuitive development environment are realized by means of a specialized software bridge between the two. These methods are used in software that allows MDSplus archives to be written and read exclusively through Labview. / text

This Master’s dissertation focuses on engineering artificial nanostructures, namely, arrays of metamolecules on a substrate (metasurfaces), with the goal to achieve the desired linear and nonlinear optical responses. Specifically, a simple analytical model capable of predicting optical nonlinearity of an individual metamolecule has been developed. The model allows one to estimate the nonlinear optical response (linear polarizability and nonlinear hyperpolarizabilities) of a metamolecule based on the knowledge of its shape, dimensions, and material. In addition, a new experimental approach to measure hyperpolarizability has also been investigated. As another research effort, a 2D plasmonic metasurface with the collective behaviour of the metamolecules known as hybrid plasmonic-Fabry-Perot cavity and surface lattice resonances was designed, fabricated and optically characterized. We experimentally discovered a novel way of coupling the microcavity resonances and the diffraction orders of the plasmonic metamolecule arrays with the low-quality plasmon resonance to generate multiple sharp resonances with the higher quality factors. Finally, we experimentally observed and demonstrated a record ultra-high-Q surface lattice resonance from a plasmonic metasurface. These novel results can be used to render highly efficient nonlinear optical responses relying on high optical field localization, and can serve as the stepping stone towards achieving practical artificial nanophotonic devices with tailored linear and nonlinear optical responses.