Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2006. / Schwan, Karsten, Committee Member ; Schimmel, David, Committee Member ; Copeland, John, Committee Member ; Owen, Henry, Committee Chair ; Wills, Linda, Committee Member.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 209-222). Also available on the Internet.

Made available in DSpace on 2014-06-11T19:26:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-14Bitstream added on 2014-06-13T19:47:29Z : No. of bitstreams: 1 carvalho_mp_me_sjrp.pdf: 275726 bytes, checksum: 321f242993a9cb5700217a8d44c3003b (MD5) / Neste trabalho estudamos problemas clássicos de controle para sistemas de equações diferenciais ordinárias lineares. O ponto de partida é a equivalência entre uma equação diferencial ordinária linear de ordem n e um sistema de n equações de primeira ordem. Problemas de controlabilidade completa, observabilidade e estabi- lização de equilíbrio são considerados. / We consider here classic problems on control for a system of ordinary diferential equations. The starting point is the equivalence between a linear equation of nth order of ordinary diferential equation and a system of n equations of first order. Problems on complete controllability, observability and stabilization of equilibrium are considered.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-06-06T20:51:09Z No. of bitstreams: 1 Jobsan Sueny de Sousa Santos – TESE (PPGEP) 2015.pdf: 5161908 bytes, checksum: e975dfcb56689717b5c8ae2d7d2ddb31 (MD5) / Made available in DSpace on 2018-06-06T20:51:09Z (GMT). No. of bitstreams: 1 Jobsan Sueny de Sousa Santos – TESE (PPGEP) 2015.pdf: 5161908 bytes, checksum: e975dfcb56689717b5c8ae2d7d2ddb31 (MD5) Previous issue date: 2015-07-31 / A contaminação do solo e das águas subterrâneas é uma preocupação crescente, visto as atividades que a desencadeiam estarem em processo de crescimento acelerado. Como exemplo, pode-se citar o vazamento em lagoas de estabilização. Tal vazamento pode se dar por rachaduras ou fissuras na base da lagoa, as quais podem estar localizadas ou distribuídas. Visando contribuir coma remediação dos locais atingidos pelos contaminantes e utilizando a fluidodinâmica computacional, neste trabalho realizou-se um estudo do transporte de tais contaminantes no solo que fica logo abaixo de uma lagoa de estabilização genérica. Para tal fim, utilizou-se a técnica dos volumes finitos e a modelagem do escoamento em meios porosos usando o pacote computacional ANSYS CFX® 12. Gerou-se uma malha estruturada bidimensional e realizaram-se as simulações considerando regime laminar, meio isotrópico, solo saturado, escoamento monofásico e isotérmico. Apesar da existência de trabalhos experimentais e/ou numéricos que apresentam o comportamento da pluma ou a variação da concentração do contaminante com o tempo, nenhum apresenta ao mesmo tempo as duas possibilidades de resultados e de forma rápida, já que as simulações duraram apenas uma hora, em média. Analisando-se os perfis de concentração dos poluentes considerados (cádmio e cobre) com a distância longitudinal e com a profundidade obteve-se uma boa concordância com o observado na literatura. O mesmo pode ser afirmado com relação ao histórico de concentração do cádmio e do cobre. Assim, além de visualizar o alcance da pluma devido à simulação, pôde-se determinar em quanto tempo ela ocorreria, de forma a fornecer um subsídio maior aos processos de remediação. / Contamination of soil and groundwater is a growing concern, as the activities that trigger are in process of accelerated growth. For example, can cite the leak stabilization ponds. Such leaks can occur for cracks or breaks in the pond base, which may be located or distributed. To contribute to remediation of sites affected by contaminants and using the computational fluid dynamics, this paper carried out a transport study of such contaminants in soil which is just below a general stabilization pond. To this end, we used the technique of finite volume and modeling of flow in porous media using the ANSYS CFX ® 12 computational package. Generated a twodimensional structured network and realized the simulations considering laminar flow, isotropic medium, saturated soil, single-phase flow and isothermal. Despite the existence of experimental and / or numerical studies show that the plume behavior or variation of the contaminant concentration with time, none has simultaneously both possibilities result and quickly, since the simulation lasted one hour on average. Analyzing the concentration profiles of the considered pollutants (cadmium and copper) with the longitudinal distance and the depth we obtained a good agreement with data from the literature. The same can be said regardinghistory of cadmium and copper. So in addition to viewing the scope of plume due to simulation, it was possible to determine how long it would take place in order to provide greater subsidy to remediation processes.

Dans cette thèse nous avons étudié différents aspects pour le contrôle de systèmes hyperboliques.Tout d'abord, nous nous sommes intéressés à des systèmes hyperboliques à commutations. Cela signifie qu'il existe une interaction entre une dynamique continue et une dynamique discrète. Autrement dit, il existe différents modes dans lesquels peut évoluer la dynamique continue: ces modes sont dictés par la dynamique discrète. Ce changement de mode peut être contrôlé (dans le cas d'une boucle fermée), ou non-contrôlé (dans le cas d'une boucle ouverte). Nous nous sommes intéressés au premier cas. Par une analyse Lyapunov nous avons construit trois règles de commutations capables de stabiliser le système. Nous avons montré comment modifier deux d'entre elles pour obtenir des propriétés de robustesse et de stabilité entrée-état. Ces règles de commutations ont été testées numériquement.Ensuite, nous avons considéré la génération de trajectoire pour des systèmes hyperboliques linéaires 2x2 par backstepping. L'étape suivante a été de considérer une action Proportionnelle-Intégrale pour stabiliser la solution du système autour de la trajectoire de référence. Pour cela nous avons construit une fonction Lyapunov non-diagonale. Nous avons montré que l'action intégrale est capable de rejeter des erreurs distribuées et frontières.Enfin, nous avons considéré des aspects numériques pour l'analyse Lyapunov. Les conditions pour la stabilité et la conception de contrôleurs obtenues par des fonctions de Lyapunov quadratiques font intervenir une infinité d'inégalités matricielles. Nous avons montré que cette complexité peut être réduite en considérant une sur-approximation polytopique de ces contraintes.Les résultats obtenus ont été illustrés par des exemples académiques et des systèmes dynamiques physiques (comme les équations de Saint-Venant et les équations de Aw-Rascle-Zhang). / In this thesis we have considered different aspects for the control of hyperbolic systems.First, we have studied switched hyperbolic systems. They contain an interaction between a continuous and a discrete dynamics. Thus, the continuous dynamics may evolve in different modes: these modes are imposed by the discrete dynamics. The change in the mode may be controlled (in case of a closed-loop system), or may be uncontrolled (in case of an open-loop system). We have focused our interest on the former case. We procedeed with a Lyapunov analysis, and construct three switching rules. We have shown how to modify them to get robustness and ISS properties. We have shown their effectiveness with numerical tests.Then, we have considered the trajectory generation problem for 2x2 linear hyperbolic systems. We have solved it with backstepping. Then, we have considered the tracking problem with a Proportionnal-Integral controller. We have shown that it stabilizes the error system around the reference trajectory with a new non-diagonal Lyapunov function. The integral action has been shown to be able to reject in-domain, as well as boundary disturbances.Finally, we have considered numerical aspects for the Lyapunov analysis. The conditions for the stability and design of controllers by quadratic Lyapunov functions involve an infinity of matrix inequalities. We have shown how to reduce this complexity by polytopic embeddings of the constraints.Many obtained results have been illustrated by academic examples and physically relevant dynamical systems (as Shallow-Water equations and Aw-Rascle-Zhang equations).

Un des plus grands défis dans la commande des robots est de combler l'écart entre la capacité de mouvement de l'humain et des robots humanoïdes. La difficulté réside dans la complexité des systèmes dynamiques représentant les robots humanoïdes: la non linéarité, le sous-actionnement, le comportement non-lisse en raison de collisions et de frottement, le nombre élevé de degrés de liberté. De plus, les robots humanoïdes sont censés opérer dans des environnements non-déterministes, qui exigent une commande temps réel avancée.L'approche qui prévaut actuellement pour faire face à ces difficultés est d'imposer diverses restrictions sur les mouvements et d'employer des modèles approximatifs des robots. Dans cette thèse, nous suivons la même ligne de recherche et proposons une nouvelle approche pour la conception de contrôleurs corps entier qui préservent l'équilibre. L'idée principale est de tirer parti des avantages des modèles approximatifs et de corps entier en les mélangeant dans un seul problème de contrôle prédictif avec des objectifs strictement hiérarchisés.La préservation de l'équilibre est l'une des principales préoccupations dans la commande des robots humanoïdes. Des recherches antérieures ont déjà établi que l'anticipation des mouvements est essentiel à cet effet. Nous préconisons que l'anticipation est utile dans ce sens comme un moyen de maintenir la capturabilité du mouvement, i.e., la capacité de s'arrêter. Nous soulignons que capturabilité des mouvements prévus peut être imposée avec des contraintes appropriées. Dans la pratique, il est fréquent d'anticiper les mouvements du robot à l'aide de modèles approximatifs afin de réduire l'effort de calcul, par conséquent, un contrôleur séparé de mouvement du corps entier est nécessaire pour le suivi. Au lieu de cela, nous proposons d'introduire l'anticipation avec un modèle approximatif directement dans le contrôleur corps entier. En conséquence, les mouvements du corps entier générés respectent les contraintes de capturabilité et les mouvements anticipes du modèle approximatif prennent en compte les contraintes et les tâches désirées pour le corps entier. Nous posons nos contrôleurs du mouvement du corps entier comme des problèmes d'optimisation avec des objectifs strictement hiérarchisés. Bien que cet ordre de priorité soit commun dans la littérature, nous croyons qu'il est souvent mal exploité.Par conséquent, nous proposons plusieurs exemples de contrôleurs, où la hiérarchisation est utile et nécessaire pour atteindre les comportements souhaités. Nous évaluons nos contrôleurs dans deux scénarios simulés, où la tâche du corps entier du robot influence la marche et le robot exploite éventuellement un contact avec la main pour maintenir son équilibre en étant debout. / One of the greatest challenges in robot control is closing the gap between themotion capabilities of humans and humanoid robots. The difficulty lies in thecomplexity of the dynamical systems representing the said robots: theirnonlinearity, underactuation, discrete behavior due to collisions and friction,high number of degrees of freedom. Moreover, humanoid robots are supposed tooperate in non-deterministic environments, which require advanced real timecontrol. The currently prevailing approach to coping with these difficulties isto impose various limitations on the motions and employ approximate models ofthe robots. In this thesis, we follow the same line of research and propose anew approach to the design of balance preserving whole body motion controllers.The key idea is to leverage the advantages of whole body and approximate modelsby mixing them within a single predictive control problem with strictlyprioritized objectives.Balance preservation is one of the primary concerns in the control of humanoidrobots. Previous research has already established that anticipation of motionsis crucial for this purpose. We advocate that anticipation is helpful in thissense as a way to maintain capturability of the motion, i.e., the ability tostop. We stress that capturability of anticipated motions can be enforced withappropriate constraints. In practice, it is common to anticipate motions usingapproximate models in order to reduce computational effort, hence, a separatewhole body motion controller is needed for tracking. Instead, we propose tointroduce anticipation with an approximate model into the whole body motioncontroller. As a result, the generated whole body motions respect thecapturability constraints and the anticipated motions of an approximate modeltake into account whole body constraints and tasks. We pose our whole bodymotion controllers as optimization problems with strictly prioritizedobjectives. Though such prioritization is common in the literature, we believethat it is often not properly exploited. We, therefore, propose severalexamples of controllers, where prioritization is useful and necessary toachieve desired behaviors. We evaluate our controllers in two simulatedscenarios, where a whole body task influences walking motions of the robot andthe robot optionally exploits a hand contact to maintain balance whilestanding.

abstract: It is estimated that wind induced soil transports more than 500 x 106 metric tons of fugitive dust annually. Soil erosion has negative effects on human health, the productivity of farms, and the quality of surface waters. A variety of different polymer stabilizers are available on the market for fugitive dust control. Most of these polymer stabilizers are expensive synthetic polymer products. Their adverse effects and expense usually limits their use. Biopolymers provide a potential alternative to synthetic polymers. They can provide dust abatement by encapsulating soil particles and creating a binding network throughout the treated area. This research into the effectiveness of biopolymers for fugitive dust control involved three phases. Phase I included proof of concept tests. Phase II included carrying out the tests in a wind tunnel. Phase III consisted of conducting the experiments in the field. Proof of concept tests showed that biopolymers have the potential to reduce soil erosion and fugitive dust transport. Wind tunnel tests on two candidate biopolymers, xanthan and chitosan, showed that there is a proportional relationship between biopolymer application rates and threshold wind velocities. The wind tunnel tests also showed that xanthan gum is more successful in the field than chitosan. The field tests showed that xanthan gum was effective at controlling soil erosion. However, the chitosan field data was inconsistent with the xanthan data and field data on bare soil. / Dissertation/Thesis / Ph.D. Civil and Environmental Engineering 2011

abstract: Sensing and controlling current flow is a fundamental requirement for many electronic systems, including power management (DC-DC converters and LDOs), battery chargers, electric vehicles, solenoid positioning, motor control, and power monitoring. Current Shunt Monitor (CSM) systems have various applications for precise current monitoring of those aforementioned applications. CSMs enable current measurement across an external sense resistor (RS) in series to current flow. Two different types of CSMs designed and characterized in this paper. First design used direct current reading method and the other design used indirect current reading method. Proposed CSM systems can sense power supply current ranging from 1mA to 200mA for the direct current reading topology and from 1mA to 500mA for the indirect current reading topology across a typical board Cu-trace resistance of 1 ohm with less than 10 µV input-referred offset, 0.3 µV/°C offset drift and 0.1% accuracy for both topologies. Proposed systems avoid using a costly zero-temperature coefficient (TC) sense resistor that is normally used in typical CSM systems. Instead, both of the designs used existing Cu-trace on the printed circuit board (PCB) in place of the costly resistor. The systems use chopper stabilization at the front-end amplifier signal path to suppress input-referred offset down to less than 10 µV. Switching current-mode (SI) FIR filtering technique is used at the instrumentation amplifier output to filter out the chopping ripple caused by input offset and flicker noise by averaging half of the phase 1 signal and the other half of the phase 2 signal. In addition, residual offset mainly caused by clock feed-through and charge injection of the chopper switches at the chopping frequency and its multiple frequencies notched out by the since response of the SI-FIR filter. A frequency domain Sigma Delta ADC which is used for the indirect current reading type design enables a digital interface to processor applications with minimally added circuitries to build a simple 1st order Sigma Delta ADC. The CSMs are fabricated on a 0.7µm CMOS process with 3 levels of metal, with maximum Vds tolerance of 8V and operates across a common mode range of 0 to 26V for the direct current reading type and of 0 to 30V for the indirect current reading type achieving less than 10nV/sqrtHz of flicker noise at 100 Hz for both approaches. By using a semi-digital SI-FIR filter, residual chopper offset is suppressed down to 0.5mVpp from a baseline of 8mVpp, which is equivalent to 25dB suppression. / Dissertation/Thesis / Ph.D. Electrical Engineering 2011

A capacidade de manter a estabilidade e integridade durante o tempo de exposição às forças destrutivas do intemperismo é um dos aspectos mais importantes da estabilização de solos em projetos de pavimentos. Esta dissertação apresenta resultados de um estudo laboratorial sobre o comportamento mecânico de um solo dispersivo estabilizado com cal. O solo estudado é um solo sedimentar de sedimentos quaternários pertencente à denominada região ocidental do Paraguai. O solo dispersivo se caracteriza por apresentar teores significativos de sódio e por apresentar erosão hídrica acelerada. O objetivo deste estudo foi avaliar a durabilidade de misturas de Solo-Cal submetidos a ciclos de molhagem e secagem. A resistência à compressão simples e resistência à vácuo saturação também foram examinadas para avaliar o desempenho de misturas de Solo-Cal. Medição da velocidade de pulso de ultra-som foi realizado como teste não destrutivo para monitorizar a rigidez das misturas. Os efeitos do tempo de cura, das características de compactação e do teor de cal, foram avaliados. Finalmente, desde um enfoque ambiental através da ferramenta de avaliação do ciclo de vida (ACV) foram avaliadas todas as misturas em função aos impactos ambientais potenciais gerados na construção de 1 m³ de subbase de Solo-Cal. Verificou-se que a durabilidade, a rigidez e a resistência de solos estabilizados com cal aumentam com o tempo de cura, com a energia de compactação e com o aumento do teor de cal. Além disso, a dispersibilidade intermediaria (ND4) que o solo apresentava em seu estado natural, muda para não dispersivo (ND1) com a adição de 2% de cal. Em conclusão ressalta-se que a mistura SC3-5 apresenta um melhor comportamento mecânico comparável com a mistura SC3-7, mas, com um menor impacto potencial gerado. / The ability to retain stability and integrity during the exposure time to the destructive forces of weathering is one of the most important aspects of soil stabilization in pavements design. This thesis presents the results of a laboratory study of the mechanical behavior of a dispersive soil stabilized with lime. The studied soil is a sedimentary soil of the quaternary sediments belonging to the so called western region of Paraguay. The dispersive soil is characterized by having significant levels of sodium and accelerated erosion. The objective of this study was to evaluate the durability of soil-lime mixtures subjected to wetting and drying cycles. Resistance to simple compression and resistance to vacuum saturation were also examined to assess the performance of soil-lime mixtures. Measurement of the ultrasonic pulse velocity was performed as non-destructive testing for monitoring the stiffness of the blends. The effects of curing time, the compression characteristics and lime content, were evaluated. Finally, all mixtures were evaluated from an environmental viewpoint by the life cycle assessment (LCA). All mixtures were evaluated according to the environmental impact in the construction of 1 m³ of Soil-Lime. It was found that durability, rigidity and resistance of soil stabilized with lime increases with cure time, with the energy of compaction and with increased lime content. Moreover, the dispersibility intermediate (ND4) showed that the soil in its natural state, changes to nondispersive (ND1) with the addition of 2% lime. In conclusion it is emphasized that the SC3-5 mixture has a better mechanical behavior comparable to SC3-7 mix, but with less potential impact generated.

Solos que contem sulfatos apresentam complicações no seu comportamento quando são tratados com estabilizadores à base de cálcio como a cal. Quando um solo que contem sulfatos reage com cal, formam-se minerais expansivos como a etringita e a taumasita que são responsáveis pela deterioração e falha de vários projetos de solos estabilizados. Tem-se bem demostrado sob ensaios de laboratório que a relação vazios/(agente cimentante) é um parâmetro adequado para a avaliação e previsão de comportamentos mecânicos, como a resistência à compressão simples de vários tipos de solos cimentados artificialmente. Este trabalho pretende encontrar se as previsões da relação vazios/cal na resistência à compressão simples são efetivas para dimensionar misturas de solos sulfatados estabilizados com cal construídas em campo. Para lograr esse objetivo executou-se um programa experimental de ensaios de laboratório em conjunto com a construção de trechos experimentais de solo-cal. Os ensaios de laboratório ajudaram comprender o comportamento de solos sulfatados estabilizados com cal, e demostraram que a relação vazios/cal controla a resistência à compressão simples desses solos estabilizados evidenciando uma relação coerente com os resultados das resistências de campo, encontrando-se que as resistências de campo e laboratório são controladas por essa relação e que podem ser previstas pela mesma Ensaios de Difração de Raios X (DRX) e Microscopia Eletrônica de Varredura (MEV) identificaram minerais expansivos (etringita) nas amostras estabilizadas com cal e cinza-cal. Finalmente em laboratório foram testadas algumas soluções recomendadas na literatura para melhorar a estabilização de solos sulfatados mediante um projeto experimental demostrando que a estabilização com cinza volante e cal melhoram consideravelmente a resistência, a durabilidade e a estabilidade volumétrica de solos sulfatados enquanto que a técnica do mellowing mostrou melhoras apenas na estabilidade volumétrica do material. / Sulfate rich soils present complications in their behavior when are treated with calcium-based stabilizers such as lime. When a soil containing sulfates reacts with lime, expansive minerals such as ettringite and thaumasite are formed which are responsible for the deterioration and failure of various stabilized soil projects. It has been well demonstrated under laboratory tests that the relationship porosity/cementing agent ratio is an appropriate parameter for the evaluation and prediction of mechanical behavior, such as the unconfined compression strength of various types of artificially cemented soils. This work intends to find out if the predictions of the relation porosity/lime in the unconfined compression strength are effective to design lime stabilized soils mixtures built in field. In order to achieve this objective an experimental program of laboratory tests was carried out together with experimental road sections of lime stabilized soils were built. The laboratory tests helped to understand the behavior of lime stabilized sulfate soils, and demonstrated that the void/lime ratio controls the unconfined compression strength of these stabilized soils and that exist a consistent relationship with the field unconfined compression strength results, finding that both, field and laboratory strengths are controlled and can be predicted by this ratio X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) tests were performed to identify expansive minerals (ettringite) on soils samples stabilized whit lime and fly ash-lime. Finally, some solutions recommended in the literature have been tested in laboratory to improve the stabilization of sulfate rich soils through an experimental design, showing that the fly ash-lime stabilization improve considerably the strength, durability and volumetric stability of the sulfate rich soils whereas that for the mellowing the improve was observed only on the volumetric stability of the material.