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Interactions between the neural and musculoskeletal systems are a prerequisite for the production of robust movement. In spite of this, the neural control and musculoskeletal structure underlying biological movements are typically studied independently, with little attention paid to how changes in one may affect the other. Understanding these interactions may be critical to improving current rehabilitation technologies and therapy methods. As an example, balance disorders are multifactorial in nature and identifying whether biomechanical or neural changes are the source of instability remains an unanswered question. I have used a combined experimental and modeling approach to understand neural and biomechanical interactions governing human balance control. I developed a simple four-bar linkage model with delayed feedback to investigate frontal-plane standing balance. Using methods from time-delay systems I present evidence from this model that biomechanical structure is important for behavioral function and show that neural control and biomechanical structure co-vary for stable human balance. Predictions from the model were tested experimentally to dissociate the effects of inertia and postural configuration on balance. In addition, I applied robust control methods to solve the difficult problem of comparing the relative performance between neuromechanical systems that differ in parameter values and predicted a common mechanism to explain changes in neural control across biomechanical contexts. In the future, the analytical tools and simulation methods I have developed can be generalized to investigate changes in neuromechanical interactions of various deficits in biomechanics (ACL rupture, amputation) and neural control (Parkinson's disease, stroke). Furthermore, this approach can be used to explain how neural control and biomechanical structure relate to the diversity of animal form and function, as well as suggest biomimetic control policies for robotics.

Markov trees generalize naturally to bounded tree-width Markov networks, onwhich exact computations can still be done efficiently. However, learning themaximum likelihood Markov network with tree-width greater than 1 is NP-hard, sowe discuss a few algorithms for approximating the optimal Markov network. Wepresent a set of methods for training a density estimator. Each method isspecified by three arguments: tree-width, model scoring metric (maximumlikelihood or minimum description length), and model representation (using onejoint distribution or several class-conditional distributions). On thesemethods, we give empirical results on density estimation and classificationtasks and explore the implications of these arguments.

This study is concerned with the effect that mean annual precipitation (P) has on the relationship between bankfull channel width (Wbf) and drainage area (Ada). Several other studies have been conducted in which relationships were developed for predicting Wbf as a function of Ada and P. In most cases, however, the relationships were developed for specific regions, e.g., physiographic regions. This study is unusual in that it evaluates the relationship between Wbf, Ada, and P over a broad area (i.e., across a range of geologic, terrestrial, and climatic environments). In one study, where a broad area was considered, the relationship between Wbf, Ada, and P was found to be linear. The dataset for this study was compiled from data in U.S. Geological Survey flood-flow-frequency reports, regional curve studies (i.e., studies in which Wbf vs. Ada relationships are developed) and other sources. A total of 435 sites that span across 12 states of the continental U.S. are represented in the dataset. Streams represented in the dataset are alluvial and have widths from 1 to 110 m, drainage areas from 0.50 to 22,000 km2, and mean annual precipitation depths ranging from 22 to 277 cm/yr. Data from the U.S. Environmental Protection Agency's Wadeable Streams Assessment study were employed in validating the results of this study. An analysis of covariance (ANCOVA) model was developed and it was determined that the intercept coefficient for the relationship between Wbf and Ada varies as follows: for P < 50 cm/yr the intercept coefficient (α) is constant; for 50 cm/yr ¡Ü P ¡Ü 100 cm/yr, α increases with P, and for P ¡Ý100 cm/yr, α is again constant. Across all values of P, the slope coefficient is constant (90% Confidence level). Changes in the relationship between Wbfand Ada are attributed to vegetation by noting that biome types changes from shrubland to forest as P increases from 50 to 100 cm/yr. These findings can be incorporated in regional curve studies and landscape evolution models (i.e., models which aim to integrate hydrology, land use history, geomorphology and climate change with models of vegetation succession).

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Apresenta-se neste trabalho um estudo sobre a largura de decaimento total do bóson de Higgs através do canal H&#8594; ZZ &#8594; (4e, 4, 2e2). Segundo o Modelo Padrão da Física de Partículas Elementares, um bóson de Higgs com massa de 126 GeV deve ter uma largura de decaimento total &#915;H = 4.15 MeV, muito abaixo da resoluções dos experimentos instalados no LHC. Isto impede uma medida direta sobre os eventos da ressonância. Recentemente foi proposto limitar &#915;H a partir da relação entre a taxa de eventos observados na região da ressonância e na região off-shell. Utilizando o pacote de análise desenvolvido pela colaboração CMS obteve-se um limite de &#915;H < 31.46(12.82) MeV em 95(68.3)% CL combinando os dados coletados pelo LHC em colisões pp em &#8730;s = 7 TeV (5.1fb-1) e em &#8730;s = 8 TeV (19.7fb -1). / We present in this work a study about the Higgs boson total width using the channel H&#8594; ZZ &#8594; (4e, 4, 2e2. According to the Standard Model of Elementary Particle Physics, the Higgs boson with mass around 126 GeV should have a total decay width of &#915;H = 4.15 MeV, very below the resolution of the experiments installed at the LHC. This fact prevents a direct measurement on the events of the Higgs resonance. Recently it was proposed limit &#915;H from the relationship between the rate of events observed in the resonance and the off-shell regions. Using the package of analysis developed by CMS collaboration was obtained a limit of &#915;H < 31.46(12.82)MeV in 95(68.3)% CL combining the data collected by the LHC in pp collisions at &#8730;s = 7 TeV (5.1fb-1)and at &#8730;s = 8 TeV (19.7fb -1).

Submitted by Maike Costa (maiksebas@gmail.com) on 2016-03-23T13:16:44Z No. of bitstreams: 1 arquivo total.pdf: 1967447 bytes, checksum: af6baac55076357093ed86cc379bab4b (MD5) / Made available in DSpace on 2016-03-23T13:16:44Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 1967447 bytes, checksum: af6baac55076357093ed86cc379bab4b (MD5) Previous issue date: 2015-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this paper, we study a special class of planar curves, convex curves of constant width. Moreover show basic examples of these curves, starting with the Reuleaux triangle that indeed is what has the smallest area when the constant width is de ned unlike the circle has the largest area and is also constant width. We generalize the construction of the Reuleaux triangle to regular polygons with odd numbers of sides that are called Reuleaux polygons. Finally we propose activities for the polygons of study in primary and secondary education as a suggestion for a school education, by reference to the polygons of Reuleaux in particular the Reuleaux triangle. / Neste trabalho, estudaremos uma classe especial de curvas planas, as curvas convexas de largura constante. Mostraremos ademais os exemplos básicos destas curvas, começando com o Triângulo de Reuleaux que de fato é o que tem a menor área quando a largura constante é de nida ao contrário do círculo que tem a maior área e também é de largura constante. Generalizamos a construção do Triângulo de Reuleaux aos polígonos regulares com um número ímpar de lados que são chamados polígonos de Reuleaux. Por último propomos atividades para o estudo de polígonos no ensino fundamental e médio como sugestão para uma educação escolar, tendo como referência os Polígonos de Reuleaux em particular o Triângulo de Reuleaux.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Apresenta-se neste trabalho um estudo sobre a largura de decaimento total do bóson de Higgs através do canal H&#8594; ZZ &#8594; (4e, 4, 2e2). Segundo o Modelo Padrão da Física de Partículas Elementares, um bóson de Higgs com massa de 126 GeV deve ter uma largura de decaimento total &#915;H = 4.15 MeV, muito abaixo da resoluções dos experimentos instalados no LHC. Isto impede uma medida direta sobre os eventos da ressonância. Recentemente foi proposto limitar &#915;H a partir da relação entre a taxa de eventos observados na região da ressonância e na região off-shell. Utilizando o pacote de análise desenvolvido pela colaboração CMS obteve-se um limite de &#915;H < 31.46(12.82) MeV em 95(68.3)% CL combinando os dados coletados pelo LHC em colisões pp em &#8730;s = 7 TeV (5.1fb-1) e em &#8730;s = 8 TeV (19.7fb -1). / We present in this work a study about the Higgs boson total width using the channel H&#8594; ZZ &#8594; (4e, 4, 2e2. According to the Standard Model of Elementary Particle Physics, the Higgs boson with mass around 126 GeV should have a total decay width of &#915;H = 4.15 MeV, very below the resolution of the experiments installed at the LHC. This fact prevents a direct measurement on the events of the Higgs resonance. Recently it was proposed limit &#915;H from the relationship between the rate of events observed in the resonance and the off-shell regions. Using the package of analysis developed by CMS collaboration was obtained a limit of &#915;H < 31.46(12.82)MeV in 95(68.3)% CL combining the data collected by the LHC in pp collisions at &#8730;s = 7 TeV (5.1fb-1)and at &#8730;s = 8 TeV (19.7fb -1).

This dissertation deals with frequency domain identification of linear dynamic systems in a deterministic set-up. Various untuned algorithms are suggested, including one which is robustly convergent and asymptotically optimal (in n-width sense) for a finite model order. The suggested algorithms can easily be implemented in commercially available software for convex optimization.

A demanda por qualidade nas aplicações envolvendo radiação laser exigiu melhorias no seu desempenho. Conseqüentemente, equipamentos mais rápidos e precisos nas medidas dos seus parâmetros são indispensáveis. Nas áreas onde o laser é empregado, três parâmetros sobressaem-se nas suas aplicações: (1) potência ou energia, (2) freqüência e (3) comprimento espacial ou largura do feixe. A determinação das bordas, isto é, da largura do feixe, está ligada a um percentual do máximo valor atingido pela energia. O diâmetro do feixe, juntamente com a energia, determina-se a densidade do feixe. Outros parâmetros como: divergência e fator de qualidade (M2), podem ser determinados também. O presente trabalho busca desenvolver um sistema de translação bidimensional que possa ser empregado na caracterização espacial do feixe de lasers. Para determinar o perfil do feixe de lasers utiliza-se o método borda-da-lâmina (knife-edge), relacionando o deslocamento da lâmina posicionada transversalmente ao feixe, com a energia transmitida. Obstruindo o feixe com uma lâmina opaca, obtêm-se a variação da energia do feixe em função da posição da lâmina. Esta variação representa a integral do perfil Gaussiano do feixe. Para a automação do sistema foi empregado o programa Labview (National Instruments). O funcionamento do protótipo mostrou-se eficiente na caracterização de feixes laser e com uma instrumentação de baixo custo para a comercialização nacional. No entanto, apresentou-se lento na aquisição de dados, tornando a tarefa de caracterização do laser mais demorada. Fatores como velocidade do motor de passo e linguagem de programação contribuíram para tornar a aquisição lenta. / The demand for quality in the applications involving laser radiation demanded improvements in its performance. Faster equipments in the measures of its parameters are indispensable. In the areas where the laser is employee, three parameters are important in its applications: (1) power or energy, (2) frequency and (3) beam spatial. The determination of the edges, i. e., the width of the beam, is correlated to a percentage of the maximum reached energy. This parameter, together with the energy, determines beam density; beyond this parameter it also possible to determine the divergence and quality factor (M2). This work searches to develop a system of bi-dimension translation that can be used in the spatial characterization of laser beam. To determine the profile of laser beam it is used the knife-edge method, that it relates the displacement of the blade located transversally to the beam, with the transmitted energy. Blocking the beam with a blade the energy variation of the beam is correlated with blade position; this variation represents the integral of the beam Gaussian profile. For the automation it will be used the Labview program(National Instruments). The prototype had showed to be efficient in the characterization of laser beams and a low cost for national commercialization; however was slow in the data acquisition resulting a longer time to acquire the laser parameters. Instrumental components as step motors or programming language had contributed to slowly acquisition.

Neutral-point-clamped (NPC) three-level inverter is capable of handling higher dc bus voltage and producing output waveform of better quality than a conventional two-level inverter. The main objective of the present work is to analyze the existing PWM schemes for two-level and three-level inverters in terms of line current ripple, and to design new PWM techniques for the NPC inverter to reduce line current distortion. Various discontinuous PWM or bus-clamping PWM (BCPWM) methods for a two-level voltage source inverter are analyzed in terms of rms line current ripple, which is evaluated by integrating the error voltage (i.e. error between the applied and reference voltages). The BCPWM schemes can be broadly classified into continual-clamp PWM (CCPWM) and split-clamp PWM (SCPWM). It is shown that split-clamp PWM scheme leads to lower harmonic distortion than CCPWM scheme. Further, advanced bus-clamping PWM (ABCPWM) methods for a two-level inverter are also studied. These methods clamp each phase to the positive and negative DC terminals over certain intervals as in BCPWM schemes, and also switch each phase at double the nominal frequency in certain other intervals unlike in BCPWM. Analytical closed-form expressions are derived for the total rms harmonic distortion due to SCPWM, CCPWM and ABCPWM schemes. Existing sinusoidal and bus-clamping PWM schemes for three-level NPC inverters are also analyzed in the space vector domain. These methods are compared in terms of line current ripple analytically as well as experimentally. As earlier, closed-form expressions are derived for the harmonic distortion factors corresponding to centered space vector PWM (CSVPWM) and the various BCPWM methods. A three-level inverter can be viewed as an equivalent two-level inverter in each sixth of the fundamental cycle or hextant. This is widely used to simplify the control of an NPC inverter. Further, this approach makes it simple to extend the BCPWM and ABCPWM methods for two-level inverters to three-level inverters. Furthermore, the method of analysis of line current ripple for the two-level inverter can also be easily extended to the three-level case. The pivot vector, which is half the length of the longest voltage vectors produced by the NPC inverter, acts as an equivalent null vector for the conceptual two-level inverter. Each pivot vector can be produced by two inverter states termed as “pivot states”. Typically, in continuous modulation methods for NPC inverter such as sinusoidal PWM and centered space vector PWM, the switching sequence (i.e. the sequence in which the voltage vectors are applied) begins and ends with the same pivot vector in each subcycle, which is equivalent to a half-carrier cycle. To be more precise, the switching sequence starts with one pivot state and ends with the other in each subcycle. However, in case of BCPWM schemes, only one pivot state is used in a subcycle. The choice of pivot state results in a variety of BCPWM schemes for an NPC inverter. Different BCPWM schemes are evaluated in terms of rms line current ripple. The optimal BCPWM, which minimizes the rms current ripple, is determined for an NPC inverter, controlled as an equivalent two-level inverter. Further, four new switching sequences are proposed here for a three-level inverter, controlled as a conceptual two-level inverter. These sequences apply the pivot vector only once, but employ one of the other two vectors twice within the subcycle. These four switching sequences are termed as “ABCPWM sequences” for three-level inverter. These sequences exploit the flexibility available in the space vector approach to PWM to switch a phase more than once in a subcycle, which results in the application of an active vector twice within the subcycle. Influence of the proposed ABCPWM sequences on the line current ripple over a subcycle is studied. The various sequences are compared in terms of rms line current ripple over a subcycle. An analytical closed-form expression for rms line current ripple over a subcycle is derived in terms of reference magnitude, angle of reference voltage vector, and subcycle duration for each of the sequences. Further, closed-form expressions are also derived for the rms current ripple over a line cycle in terms of modulation index and subcycle duration, corresponding to the various sequences. The four proposed ABCPWM sequences for the NPC inverter can be grouped into two pairs of sequences. Each pair of sequences is shown to perform better than the individual sequences, if the two sequences are employed in appropriate spatial regions. Hence, with these two pairs of sequences, two hybrid PWM schemes are proposed. Finally, a hybrid PWM technique is proposed which employs all five sequences (conventional and proposed four sequences) in spatial regions where each performs the best. This is termed as “five-zone hybrid PWM”. The total harmonic distortion (THD) in the motor current, pertaining to all the proposed schemes, is studied theoretically over the entire range of linear modulation. The theoretical investigations are validated experimentally on a 2.2 kW, 415V, 4.9A, 50 Hz induction motor drive. The no-load current THD is measured over a range of fundamental frequency from 10 Hz to 50 Hz in steps of 2 Hz for the various PWM methods. Theoretical and experimental results bring out the reduction in current THD due to the proposed BCPWM schemes at fundamental frequencies of 45 Hz and above, compared to CSVPWM. The ABCPWM methods improve the performance at higher as well as lower modulation indices. Further improvement is achieved with the proposed five-zone hybrid PWM. At the rated frequency (50 Hz) of the drive, the improvement in line current distortion is around 36% with this hybrid PWM scheme over CSVPWM. The reduction in THD is also experimentally verified at different loads on the motor. The difference between the top and bottom capacitor voltages is measured at various operating conditions, corresponding to CSVPWM and the proposed schemes. No significant difference is observed in the dc neutral voltage shifts with the different proposed schemes and CSVPWM method. Thus, the proposed methods improve the THD at low and high speed ranges without appreciable worsening of the dc voltage unbalance.