An ID generating circuit is unquestionably the core of a chipless RFID tag. For convenience of printing process and cost consideration, the circuit should be kept as simple as possible. Based on the cognition, an 8-bit time-domain based ID generating circuit that merely consists of a ML and eight capacitors was offered, and implemented on photo-paper substrates via inkjet printing process. In addition to the experimental measurements, the circuit was also input into circuit simulators for cross-validation. The good agreement between simulations and measurements is observed, exhibiting the tag technical feasibility. Besides of low cost, the tag has wide compatibility with current licensed RFID spectrum, which will facilitate the future deployment in real applications. Compared   to  time-domain   based  chipless   tags,  frequency   signatures   based chipless RFID tags are expected to offer a larger coding capacity. As a response, we presented a 10-bit frequency-domain based chipless RFID tag. The tag composed of ten configurable LC resonators was implemented on flexible polyimide substrate by using  fast  toner-transferring  process.  Field  measurements  revealed  not  only  the practicability  of  the  tag,  but  also  the  high  signal  to  noise  ratio  (SNR).  Another frequency domain tag consists of a configurable coplanar LC resonator. With the use of all printing process, the tag was for the first time realized on common packaging papers.  The tag feasibility was confirmed by subsequent measurements. Owing to the ultra-low cost potential and large SNR, The tag may find wide applications in typical RFID solutions such as management of paper tickets for social events and governing of smart documents. Ultra wide band (UWB) technology possesses a number of inherent merits such as high speed communication and large capacity, multi-path immunity, accurate ranging and positioning, penetration through obstacles, as well as extremely low-cost and low- power transmitters. Thus, passive UWB RFIDs are expected to play an important pole in  the future identification applications for IoT. We explained the feature difference between  UWB  chipless  tags  and  chip  based  tags,  and  forecasted  the  applications respectively  based on the comparison  between the two technologies.  It is expected that the two technologies will coexist and compensate each other in the applications of IoT. Lastly, the thesis ends up with brief summary of the author’s contributions, and technical prospect for the future development of printable chipless RFID tags. / <p>QC 20140304</p>

This dissertation presents a study on velocity modeling using ocean-bottom seismometer data (OBS) collected in 2004 and 2006 on the western Scotian slope. Gas hydrate and free gas concentrations and their distribution along the Scotian margin were derived based on the velocity results modeled with two different OBS data sets. A strong velocity increase (140-300 m/s) associated with gas hydrate was modeled for a depth of 220 m below seafloor (bsf). At the base of that high velocity zone (330 mbsf) the velocity decreases with 50-130 m/s. This depth is associated with the depth of the bottom-simulating reflector (BSR) observed in previous 2-D seismic reflection data. The gas hydrate concentrations (2-18 %) based on these velocities were calculated with an effective medium model. The velocity modeling shows that a sparser OBS spacing (~ 1 km) reveals more velocity uncertainties and smaller velocity contrasts than a denser (100 m) spaced OBS array. The results of the travel-time inverse modeling are applied in a waveform inverse modeling with OBS data in the second part of the thesis. The modeling tests were performed to obtain information on OBS instrument spacings necessary to detect low-concentration gas hydrate occurrences. The model runs show that an increase in instrument spacing leads to an increasing loss of model smoothness. However, large instrument spacings (>500 m) are beneficial for covering a wide target region with only using a few instruments, but decreasing the lateral resolution limits of the subsurface targets. In general half of the instrument spacing defines the lower boundary for the lateral width of the target structure. Waveform modeling with the 2006 OBS data has shown that low frequencies (<8 Hz) in the source spectrum are necessary to recover the background velocity of the model. The starting model derived from travel-time inversion of the 2006 data is not close enough to the true model. Thus the first-arrival waveforms do not match within half a cycle. Modeling with a starting frequency of 8 Hz and and applying data with a low signal-to-noise ratio (1.25) introduces artifacts into the final model result without updating the velocity. / Graduate

La résolution de l'équation des ondes acoustiques et élastiques en 3D dans le domaine fréquentiel représente un enjeu majeur dans le cadre de l'inversion des formes d'ondes pour l'imagerie haute résolution de cibles crustales (Virieux, 2009). Après discrétisation, ce problème revient à résoudre un système linéaire à valeurs complexes, creux, de grande taille non défini et mal conditionné. Les méthodes d'inversion sismique requièrent la solution de ce problème pour l'évaluation du problème direct pour un grand nombre de sources (plusieurs milliers voir dizaines de milliers). Dans l'approximation acoustique, les méthodes directes sont privilégiées. Cependant, le coût mémoire de ces méthodes les rendent aujourd'hui inutilisables pour résoudre les problèmes élastiques 3D. En raison de leur plus faible coût mémoire, les méthodes itératives pour les équations en fréquence peuvent être considérées pour l'élastodynamique. Cependant, une convergence rapide passe par des préconditionneurs adaptés pour les solveurs itératifs. Par ailleurs, les stratégies pour résoudre des systèmes linéaires avec des seconds membres multiples ne sont pas aussi efficaces que pour les méthodes directes. La modélisation dans le domaine temporelle quant à elle présente une importante complexité en coût de calcul et cette complexité croît linéairement avec le nombre de sources.Dans cette thèse, l'approche utilisant un solveur itératif est considérée. Le solveur itératif CARP-CG introduit par Gordon (2010) est considéré. Cette méthode est basée sur la méthode de Kaczmarz qui transforme un système linéaire mal conditionné en un système hermitien, positif et qui peut être résolu en utilisant les méthodes du type gradient conjugué (CG). Dans des configurations de forts contrastes et hétérogénéités, ce solveur s'est révélé être extrêmement robuste alors que les méthodes itératives standards basées sur les sous-espaces de Krylov telles que GMRES et BiCGSTAB nécessitent l'utilisation d'un préconditionneur pour converger (Li, 2015). Malgré les bonnes propriétés de la méthode CARP-CG, le nombre d'itérations nécessaires pour atteindre une précision suffisante reste néanmoins élevé. Je présente alors une stratégie de préconditionnement adaptée au problème de propagation des ondes et à la méthode CARP-CG. Ce préconditionneur est un inverse creux et approché d'un opérateur de propagation des ondes fortement amorti. Le calcul du préconditionneur est réalisé grâce un algorithme massivement parallèle pour les architectures à mémoire distribuée.La méthode développée est appliquée à des cas d'étude réalistes. Les applications sont faites sur des modèles synthétiques 2D dans l'approximation visco-acoustique pour des fréquences allant jusqu'à 40 Hz puis dans l'approximation élastique pour des fréquences allant jusqu'à 20 Hz. Ces études montrent l'efficacité de la méthode CARP-CG munie de la stratégie de préconditionnement. Le nombre d'itérations est fortement réduit (jusqu'à un facteur 9) permettant d'améliorer considérablement la complexité de la méthode CARP-CG. Des gains en temps de calcul allant jusqu'à un facteur 3.5 sont ainsi obtenus. La méthode est ensuite appliquée à un cas 3D synthétique et réaliste dans l'approximation visco-élastique pour des fréquences allant de 1.25 Hz à 7.5 Hz. Des résultats encourageants sont obtenus. Munie du préconditioneur, la méthode CARP-CG permet de résoudre ces systèmes linéaires deux fois plus rapidement.La stratégie de préconditionnement implique la nécessité de plus grandes ressources en mémoire pour le solveur itératif; cependant, elles ne constituent pas une limitation pour la méthode et restent très négligeables devant celles requises par les solveurs directs. La principale limitation réside dans le temps de calcul qui demeure assez significatif. Cependant, cette méthode constitue un solveur compétitif comparé aux autres solveurs en temps et direct utilisés aujourd'hui dans le cadre de l'inversion des formes d'ondes. / A robust and efficient wave modeling method is the cornerstone of high resolution seismic inversion methods such as the frequency-domain Full Waveform Inversion (Virieux, 2009). After discretization, frequency-domain wave modeling amounts to the solution of large (up to several billion of unknowns for realistic case studies), sparse, indefinite and ill-conditioned linear systems. Furthermore, seismic inversion methods require the solution of this problem for numerous sources (from several thousands up to tens of thousands). In the acoustic approximation, 3D real case studies can be handled efficiently using direct solvers. However because of their tremendous intrinsic memory requirements, they are not yet adapted to the solution of the 3D elastodynamics equations. Iterative solvers provide an alternative to direct solvers. However, they require a preconditioning strategy to ensure convergence for the frequency-domain wave equation. Besides, multiple right-hand sides linear systems are not treated as efficiently as direct solvers do.In this thesis, we are interested in the use of a robust iterative solver adapted to the solution of these systems called CARP-CG (Gordon, 2010). The CARP-CG method has shown robust convergence properties for 2D and 3D elastic problems in highly heterogeneous media compared to standard Krylov methods such as GMRES or Bi-CGSTAB which require the use of a preconditioner to ensure convergence (Li, 2015). Despite the good convergence properties of CARP-CG, the latter still requires a large number of iterations to reach sufficient accuracy. I introduce an efficient preconditioning strategy adapted to the CARP-CG method and the frequency-domain wave problem. This preconditioner is computed as a sparse approximate inverse of a strongly damped wave propagation operator. The computation of the preconditioner is performed in a massively parallel algorithm for distributed memory architectures.The efficiency of the preconditioner is evaluated on several case studies. First, applications are performed on realistic synthetic models in the 2D visco-acoustic approximation (up to $40$ Hz) and the 2D visco-elastic approximation (up to $20$ Hz). These studies show that the CARP-CG method together with the preconditioning strategy is robust and efficient. The number of iterations is significantly reduced (up to a factor $9$) enabling a speedup in the computation time by a factor up to $3.5$. Second, this method is investigated in the 3D elastic approximation on a realistic synthetic case study on the range of frequencies 1.25 to 7.5 Hz. Very encouraging results are obtained with a significant reduction in the number of iterations. A slow increase of the number of iterations with respect to the frequency is noted.This preconditioning strategy adapted to the CARP-CG method implies larger memory requirements. However, this extra memory cost remains one order lower compared to direct solver memory requirement, and should be affordable on standard HPC facilities. The main bottleneck preventing from the possible use of this iterative solver for 3D elastic FWI remains the computation time for the wave equation solves.

abstract: Pulse Density Modulation- (PDM-) based class-D amplifiers can reduce non-linearity and tonal content due to carrier signal in Pulse Width Modulation - (PWM-) based amplifiers. However, their low-voltage analog implementations also require a linear- loop filter and a quantizer. A PDM-based class-D audio amplifier using a frequency-domain quantization is presented in this paper. The digital-intensive frequency domain approach achieves high linearity under low-supply regimes. An analog comparator and a single-bit quantizer are replaced with a Current-Controlled Oscillator- (ICO-) based frequency discriminator. By using the ICO as a phase integrator, a third-order noise shaping is achieved using only two analog integrators. A single-loop, singlebit class-D audio amplifier is presented with an H-bridge switching power stage, which is designed and fabricated on a 0.18 um CMOS process, with 6 layers of metal achieving a total harmonic distortion plus noise (THD+N) of 0.065% and a peak power efficiency of 80% while driving a 4-ohms loudspeaker load. The amplifier can deliver the output power of 280 mW. / Dissertation/Thesis / Ph.D. Electrical Engineering 2011

Made available in DSpace on 2014-06-11T19:27:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-05-17Bitstream added on 2014-06-13T20:35:25Z : No. of bitstreams: 1 borges_as_me_ilha.pdf: 1848055 bytes, checksum: baddb0e3ae6ff7e75ac2a367efd5a7a3 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O presente trabalho propõe o estudo e implementação de uma metodologia para a estimação dos parâmetros modais de estruturas utilizando uma técnica de identificação baseada apenas na resposta do modelo, denominada Decomposição no Domínio da Freqüência (DDF). Para tal são abordados os conceitos básicos envolvidos na análise modal, análise modal baseada apenas na resposta e métodos de identificação. A formulação do algoritmo é baseada na decomposição da matriz densidade espectral de potência utilizando a técnica da decomposição em valores singulares (SVD). A decomposição da matriz densidade espectral nas linhas de freqüências correspondentes aos picos de amplitude, permite a estimativa dos modos de vibrar do sistema. Tem-se ainda que, o primeiro vetor singular obtido com a decomposição da matriz densidade espectral, para cada linha de freqüência, na região em torno do modo, contém as respectivas informações daquele modo e o correspondente valor singular leva a uma estimativa da função densidade espectral de um sistema de um grau de liberdade (1GL) equivalente. Neste caso, a matriz densidade espectral de saída é decomposta em um conjunto de sistemas de 1 grau de liberdade. Posteriormente, esses dados são transformados para o domínio do tempo, utilizando a transformada inversa de Fourier, e as razões de amortecimento são estimadas utilizando o conceito de decremento logaritmo. A metodologia é avaliada, numa primeira etapa, utilizando dados simulados e posteriormente utilizando dados experimentais. / The present work proposes the study and implementation of a methodology for the estimating of the modal parameters of structures by using the output-only data. The technique called Frequency Domain Decomposition (DDF) identifies the modal parameters without knowing the input. For that, it is discussed the basic concepts involved in identification, modal analysis and output-only modal analysis. The formulation of the algorithm is based on the decomposition of the power spectral density matrix by using the singular values decomposition technique (SVD). The decomposition of the spectral density matrix for the lines of frequency corresponding to the amplitude peaks, allows the estimating of the modes shape of the system. Additionally, the first singular vector obtained with the decomposition of the spectral density matrix, for each line of frequency, in the area around of the peak, contains the respective information of that mode. The corresponding singular value leads to an estimating of the spectral density function of an equivalent system of one degree of freedom. Therefore, the output spectral density matrix is decomposed in a set of one degree of freedom system. Later on, those data are transformed for the time domain by using the inverse Fourier transform and the damping ratios estimated from the crossing times and the logarithm decrement of the corresponding single degree of freedom system correlation function. The methodology is evaluated using simulated and experimental data.

Made available in DSpace on 2014-06-11T19:22:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-11-30Bitstream added on 2014-06-13T20:27:56Z : No. of bitstreams: 1 carvalho_cg_me_ilha.pdf: 1013674 bytes, checksum: 2251b87eda27daaaa94e554489ebe5d0 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho é desenvolver uma metodologia para definir um condutor equivalente para um condutor múltiplo. O método baseia-se no fato de que os parâmetros dos subcondutores estão distribuídos ao longo do comprimento dos mesmos e, deste modo, cada subcondutor deve ser tratado como uma linha de transmissão. Inicialmente são obtidas as relações entre as correntes e tensões nos dois terminais de cada subcondutor. Em seguida, considera-se que a corrente no condutor múltiplo deve ser igual à corrente no condutor equivalente. Uma vez que as tensões e correntes nos terminais do condutor equivalente são conhecidas, é possível obter a impedância longitudinal e a admitância transversal deste condutor. O método desenvolvido foi aplicado em um condutor múltiplo hipotético constituído de dois subcondutores. Os resultados obtidos com este método são comparados com o método clássico de obtenção do condutor equivalente, que se baseia no raio médio geométrico dos subcondutores do condutor múltiplo. Para isto foi mostrado que quando o raio médio geométrico é usado para definir um condutor equivalente de um condutor múltiplo, os parâmetros longitudinais e transversais do condutor equivalente são afetados. / The objective of this work is to improve a methodology to define an equivalent conductor for a bundled conductor. The proposed methodology takes into account that the longitudinal and transversal parameters are distributed along the subconductors. This way, each subconductor of a bundled conductor needs to be considered as being a transmission line. Initially the relationships among currents and voltages at sending and receiving end of each subcondutor are obtained. Then, it is considered that total currents and voltages at sending and receiving end of the bundled conductor is equal to currents and voltages at sending and receiving end of the equivalent conductor. Taking into account that parameters of the equivalent conductor are distributed parameters, it is possible to obtain them from currents and voltages at sending and receiving end. The proposed methodology was applied in a hypothetical bundled conductor constituted by two subconductors. The results were compared with results obtained by using geometric mean radius. It was shown that when geometric mean radius is used to define an equivalent conductor of a bundled conductor, the longitudinal and transversal parameters of the equivalent conductor are severely affected.

Neste trabalho, propomos um novo mÃtodo de modulaÃÃo Ãptica usando um filtro acÃstoÃptico sintonizÃvel (AOTF) convencional e um filtro acÃsto-Ãptico com polarizaÃÃo sintonizÃvel (AOTPF) baseado em fibra de cristal fotÃnico (PCF), onde portas lÃgicas Ãpticas E e OU sÃo obtidas pela operaÃÃo simultÃnea da modulaÃÃo em dupla banda lateral Ãptica (ODSB) e da modulaÃÃo por posiÃÃo de pulso no domÃnio da frequÃncia (PPFDM). Estes dispositivos sÃo operados com pulsos sÃlitons ultracurtos de 100 ps e 55,5 fs para o AOTF convencional e para o AOTPF baseado em PCF, respectivamente. Desta forma, um pulso leva dois bits de informaÃÃo apÃs ser criptografado pela modulaÃÃo proposta aqui. Em seguida, analisamos a modulaÃÃo ODSB-PPFDM para os pulsos de entrada, polarizados nos dois modos de entrada, permitindo uma variaÃÃo no parÃmetro de codificaÃÃo &#949;cod para cada pulso de entrada. Para o AOTF convencional, consideramos uma diferenÃa de fase de dfi = pi rad entre ambos os pulsos de entrada. Como resultado, obtivemos vÃrios valores do parÃmetro de codificaÃÃo |&#949;cod| onde as operaÃÃes lÃgicas E e OU foram possÃveis. JÃ para o AOTPF baseado em PCF, consideramos uma diferenÃa de fase de dfi = 1,28pi rad entre ambos os pulsos de entrada para obtermos valores do parÃmetro de codificaÃÃo |&#949;cod| onde as operaÃÃes lÃgicas E e OU foram possÃveis. / We propose a new method of optical modulation using a conventional Acousto-Optic Tunable Filter (AOTF) and an Acoustic Optic Tunable Polarization Filter (AOTPF) based on Photonic Crystal Fiber (PCF). In both devices the all-optical logic gates, namely AND and OR, are obtained by simultaneously operation of Optical Double Sideband (ODSB) modulation and a Pulse Position Frequency Domain Modulation (PPFDM). These devices shall operate with ultrashort soliton light pulses 100 ps and 55.5 fs for conventional AOTF and all-fiber AOTPF based on PCF, respectively. In this way, a pulse will carry two bits of information after been encoded by the modulation proposed here. We then analyze the modulation ODSB - PPFDM for input pulses, polarized in the two input modes, allowing a variation in the modulation parameter &#949;cod for each input pulse. For conventional AOTF, a phase difference dfi = pi rad was considered between both input pulses, obtaining various values of the coding parameter offset |&#949;cod| where the AND and OR logic operations were possible. For the all-fiber AOTPF based on PCF, a phase difference of dfi = 1,28pi rad was necessary between both input pulses to generate values of coding parameter offset |&#949;cod|, for which AND and OR logic operations were possible.

Made available in DSpace on 2014-08-20T14:33:08Z (GMT). No. of bitstreams: 1 Dissertacao_Viviane_Santos_Silva_Terra.pdf: 2073573 bytes, checksum: 19ddda03c961d08b0c0179b761552932 (MD5) Previous issue date: 2010-02-12 / The South region of Brazil (Pelotas, state of Rio Grande do Sul) is responsible for the production of temperate fruit trees. Among them, the peach crop has been a good option for crops diversification. The knowledge of the amount of available soil water to supply water needs during the peach different stages of development is of interest to the agronomic point of view. In this sense, we highlight the importance of the use of irrigation in peach orchards in order to provide an adequate crop water supply. It is therefore important to know the response of peach to water deficit so that we can assess the influence of the practice of irrigation in crop production. Among the methodologies, the soil water balance, which consists of applying the equation of conservation of mass, has been used. Based on this, the main objective of this work was to evaluate and quantify the different components of water balance in a Red Yellow Podzolic soil, planted with peach trees, cultivar Maciel, under irrigation and without irrigation and to verify the adequacy of Domain Reflectometry Frequency (FDR) equipment for monitoring the water content over time. The evaluation and quantification of different components of water balance of soil water were measured in an experimental area which belongs to Embrapa Clima Temperado, Pelotas-RS, Brazil, planted with peach cultivar Maciel, nearby plants irrigated and not irrigated. For this, the water balance calculation was carried out weekly and divided into 32 periods, of which 4 periods (12, 20, 24 and 26) were discarded because they had precipitation above 30 mm week-1. The experimental area containing irrigated and no irrigated plants was divided into five strips. The irrigated plants belonged to the strip 1 (tubes 3 and 6), strip 2 (tube 2) and strip 3 (tube 1), each one with an area of 0.5 m². The no-irrigated area belonged to the strip 4 (tube 8) and 5 (tube 7), with an area of 1 meters each one. Strips 1, 2 and 4 were under canopy and the other outside of the canopy. Rainfall was measured by rain gauges; irrigation water supply was made based on the average daily evapotranspiration of the region; the variation of water storage in the soil was measured by readings of soil water content up to 0.50 m depth, using an equipment based on reflectometry in the frequency domain (FDR) which was calibrated from readings of tensiometers; the runoff and internal drainage or capillary rise were neglected; and the actual evapotranspiration (ETr) was taken as the unknown variable. From the results we can conclude that it is possible to use an indirect method, using tensiometers and soil water retention curves to obtain calibration curves of the reflectometry equipment in the frequency domain (FDR); the adopted irrigation management, based on the average evapotranspiration of the region, may not be sufficient to supply the water requirements of peach crop; peach trees with water supply through irrigation have higher values of actual evapotranspiration; and soil water storage ranged in all irrigated and no irrigated strips between 60 and 140 mm week-1, unaffected by the adopted treatments in the study. / A região de Pelotas é responsável pela grande produção de frutíferas de Clima Temperado, em especial a cultura do pessegueiro que tem sido uma boa opção para a diversificação de culturas. O conhecimento da quantidade de água disponível no solo para atender as necessidades hídricas do pessegueiro durante os seus diferentes estádios de desenvolvimento é de interesse do ponto de vista agronômico. Neste sentido, destaca-se o uso da irrigação na cultura do pessegueiro, visando fornecer a cultura um adequado suprimento de água. Desta forma, é importante conhecer a resposta do pessegueiro ao déficit hídrico para que se possa avaliar a influência da prática da irrigação na produção da cultura. Dentre as metodologias que tem sido utilizada, destaca-se a do balanço hídrico no solo, que consiste na aplicação da equação de conservação de massa. Baseado no acima exposto, este trabalho teve como o objetivo principal avaliar e quantificar os diferentes componentes do balanço hídrico em um solo Argissolo Vermelho Amarelo, cultivado com plantas de pessegueiro, cultivar Maciel, em condições de irrigação e sem irrigação, bem como verificar a adequação de um equipamento de Reflectometria no Domínio da Frequência (FDR) para monitorar o seu conteúdo de água ao longo do tempo. A avaliação e quantificação dos diferentes componentes do balanço hídrico de água no solo foram realizadas em uma área experimental pertencente a Embrapa Clima Temperado, Pelotas-RS, cultivada com pessegueiro, cultivar Maciel, próximo às plantas irrigadas e não irrigadas. Para tal, o cálculo do balanço hídrico foi realizado semanalmente e dividido em 32 períodos, sendo a área experimental contendo as plantas irrigadas e não irrigadas dividida em cinco faixas. As plantas irrigadas pertenciam a faixa 1 (tubos 3 e 6), faixa 2 (tubo 2) e faixa 3 (tubo 1), cada uma com área de 0,5 m². As não irrigadas pertenciam a faixa 4 (tubo 8) e faixa 5 (tubo 7), com uma área de 1,0 m² cada. As faixas 1, 2 e 4 encontravamse na subcopa da planta e as demais fora da copa. A precipitação foi medida por meio de pluviômetros; a irrigação foi feita diariamente baseada na média evapotranspirativa da região; a variação da armazenagem de água no solo foi medida por meio de leituras de umidade do solo até 0,50 m de profundidade, utilizando-se um equipamento baseado na reflectometria no domínio da frequência (FDR), o qual foi calibrado a partir de leituras de tensiometria; o escoamento superficial e a drenagem interna ou ascensão capilar foram desprezados; a evapotranspiração foi tomada como variável incógnita. A partir dos resultados podese concluir que é possível a utilização de um método indireto, usando tensiômetros e curvas de retenção para a obtenção de curvas de calibração do equipamento de reflectometria no domínio da frequência (FDR); o manejo de irrigação adotado, baseado na média de evapotranspiração da região, pode não ser suficiente para suprir a demanda hídrica da cultura do pessegueiro; plantas de pessegueiro com suprimento hídrico por meio da irrigação apresentam valores maiores de evapotranspiração real e a armazenagem variou em todas as faixas irrigadas e não irrigadas entre 60 a 140 mm semana-1, não sendo afetada pelos manejos adotados no estudo.

Abstract The quantitation of the variability in cardiovascular signals provides information about the autonomic neural regulation of the heart and the circulatory system. Several factors have an indirect effect on these signals as well as artifacts and several types of noise are contained in the recorded signal. The dynamics of RR and QT interval time series have also been analyzed in order to predict a risk of adverse cardiac events and to diagnose them. An ambulatory measurement setting is an important and demanding condition for the recording and analysis of these signals. Sophisticated and robust signal analysis schemes are thus increasingly needed. In this thesis, essential points related to ambulatory data acquisition and analysis of cardiovascular signals are discussed including the accuracy and reproducibility of the variability measurement. The origin of artifacts in RR interval time series is discussed, and consequently their effects and possible correction procedures are concidered. The time series including intervals differing from a normal sinus rhythm which sometimes carry important information, but may not be as such suitable for an analysis performed by all approaches. A significant variation in the results in either intra- or intersubject analysis is unavoidable and should be kept in mind when interpreting the results. In addition to heart rate variability (HRV) measurement using RR intervals, the dy- namics of ventricular repolarization duration (VRD) is considered using the invasively obtained action potential duration (APD) and different estimates for a QT interval taken from a surface electrocardiogram (ECG). Estimating the low quantity of the VRD vari- ability involves obviously potential errors and more strict requirements. In this study, the accuracy of VRD measurement was improved by a better time resolution obtained through interpolating the ECG. Furthermore, RTmax interval was chosen as the best QT interval estimate using simulated noise tests. A computer program was developed for the time interval measurement from ambulatory ECGs. This thesis reviews the most commonly used analysis methods for cardiovascular vari- ability signals including time and frequency domain approaches. The estimation of the power spectrum is presented on the approach using an autoregressive model (AR) of time series, and a method for estimating the powers and the spectra of components is also presented. Time-frequency and time-variant spectral analysis schemes with applica- tions to HRV analysis are presented. As a novel approach, wavelet and wavelet packet transforms and the theory of signal denoising with several principles for the threshold selection is examined. The wavelet packet based noise removal approach made use of an optimized signal decomposition scheme called best tree structure. Wavelet and wavelet packet transforms are further used to test their effciency in removing simulated noise from the ECG. The power spectrum analysis is examined by means of wavelet transforms, which are then applied to estimate the nonstationary RR interval variability. Chaotic modelling is discussed with important questions related to HRV analysis.ciency in removing simulated noise from the ECG. The power spectrum analysis is examined by means of wavelet transforms, which are then applied to estimate the nonstationary RR interval variability. Chaotic modelling is discussed with important questions related to HRV analysis.

Inferência da força de interação nos fenômenos físicos/biológicos é objetivo comum a diversas áreas da ciência. Em particular, nas neurociências tem-se assistido a uma mudança no paradigma experimental em que a atenção tem-se voltado à compreensão da interação entre grupamentos neuronais. Em vista desta demanda surgiram naturalmente diversos métodos estatísticos de medida de dependência entre grupamentos neurais. Alguns foram desenhados para inferência de fluxo de informação, sem contudo precisar o que se entende por fluxo de informação, gerando consequentemente controvérsias na literatura. O principal objetivo deste trabalho é aplicar os conceitos da Teoria da Informação na análise de processos estacionários de segunda ordem para precisar as idéias de fluxo de informação utilizadas na literatura de forma ad hoc e obter um melhor entendimento da relação existente entre as diferentes medidas de dependência propostas. / We study the relationship between different measures of causality or information flow. We show that the concept of partial measures of dependence are related to the definition of inverse random variables.