Cardiovascular disease (CVD) is the leading cause of death in the United States. Analysis of vascular reactivity (VR) in response to brachial artery occlusion is used to estimate arterial health and to determine the likelihood of future cardiovascular complications. Development of a sensitive technique to assess VR is fundamental to the field of preventive cardiology. The conventional technique to study VR is by monitoring arterial diameter changes during hyperemia following occlusion using ultrasound based methods. Such measurements require highly qualified technicians and expensive equipment; and are complicated by signal noise introduced by motion and posture among others. It is well known that tissue temperature changes are a direct response to variations in blood flow, and it has been observed in small clinical studies that variations in fingertip temperature during brachial artery occlusion and subsequent hyperemia is a simple surrogate for the measurement of vascular reactivity and endothelial dysfunction. Given the promising nature of thermal monitoring to study VR, this thesis focuses on the analysis of the underlying physics affecting fingertip temperature during vascular occlusion and subsequent hyperemia. I will quantify the contribution of hemodynamic, anatomical and environmental factors over digit temperature changes, which will serve to determine the sensitivity of the digital thermal monitoring (DTM) technique. I have quantified the effect of several contributing factors to fingertip temperature and DTM results. The aims of this thesis focus on: (1) creation of a mathematical model of heat transfer at baseline, during, and after a reactive hyperemia test; and (2) validation of the model and experimental analysis of thermal and flow parameters in healthy volunteers. The proposed project is an innovative study that intends to show and quantify the relationship between VR and digital thermal reactivity, translating mathematical models based on the physics of heat transfer and fluid mechanics to clinical application. The parametric studies performed with the zeroth order model served to separate the contribution of environment and blood flow over the temperature curves measured during brachial artery occlusion. The thermal models developed were able to reproduce the trend of the temperature response observed experimentally at the fingertip.

Continued improvements of transceiver systems-on-a-chip play a key role in the advancement of mobile telecommunication products as well as wireless systems in biomedical and remote sensing applications. This dissertation addresses the problems of escalating CMOS process variability and system complexity that diminish the reliability and testability of integrated systems, especially relating to the analog and mixed-signal blocks. The proposed design techniques and circuit-level attributes are aligned with current built-in testing and self-calibration trends for integrated transceivers. In this work, the main focus is on enhancing the performances of analog and mixed-signal blocks with digitally adjustable elements as well as with automatic analog tuning circuits, which are experimentally applied to conventional blocks in the receiver path in order to demonstrate the concepts. The use of digitally controllable elements to compensate for variations is exemplified with two circuits. First, a distortion cancellation method for baseband operational transconductance amplifiers is proposed that enables a third-order intermodulation (IM3) improvement of up to 22dB. Fabricated in a 0.13µm CMOS process with 1.2V supply, a transconductance-capacitor lowpass filter with the linearized amplifiers has a measured IM3 below -70dB (with 0.2V peak-to-peak input signal) and 54.5dB dynamic range over its 195MHz bandwidth. The second circuit is a 3-bit two-step quantizer with adjustable reference levels, which was designed and fabricated in 0.18µm CMOS technology as part of a continuous-time SigmaDelta analog-to-digital converter system. With 5mV resolution at a 400MHz sampling frequency, the quantizer's static power dissipation is 24mW and its die area is 0.4mm^2. An alternative to electrical power detectors is introduced by outlining a strategy for built-in testing of analog circuits with on-chip temperature sensors. Comparisons of an amplifier's measurement results at 1GHz with the measured DC voltage output of an on-chip temperature sensor show that the amplifier's power dissipation can be monitored and its 1-dB compression point can be estimated with less than 1dB error. The sensor has a tunable sensitivity up to 200mV/mW, a power detection range measured up to 16mW, and it occupies a die area of 0.012mm^2 in standard 0.18µm CMOS technology. Finally, an analog calibration technique is discussed to lessen the mismatch between transistors in the differential high-frequency signal path of analog CMOS circuits. The proposed methodology involves auxiliary transistors that sense the existing mismatch as part of a feedback loop for error minimization. It was assessed by performing statistical Monte Carlo simulations of a differential amplifier and a double-balanced mixer designed in CMOS technologies.

Submitted by ROGÉRIO ZANARDE BARBOSA null (rogerio.zanarde@hotmail.com) on 2016-02-15T16:09:03Z No. of bitstreams: 1 TESE_ROGERIO_FINAL (pdf).pdf: 3648253 bytes, checksum: 709d16b4ff9a0a30de2b8ad951471639 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-02-16T17:03:04Z (GMT) No. of bitstreams: 1 barbosa_rz_dr_bot.pdf: 3648253 bytes, checksum: 709d16b4ff9a0a30de2b8ad951471639 (MD5) / Made available in DSpace on 2016-02-16T17:03:04Z (GMT). No. of bitstreams: 1 barbosa_rz_dr_bot.pdf: 3648253 bytes, checksum: 709d16b4ff9a0a30de2b8ad951471639 (MD5) Previous issue date: 2015-12-16 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Este é um trabalho de tecnologia computacional aplicada na área agrícola, cujo objetivo principal do trabalho é desenvolver uma rede de sensores sem fio, que envolve aspectos de software e hardware, para o monitoramento térmico no interior de uma casa de vegetação. Além da rede propriamente dita, o trabalho também inclui a sua aplicação no levantamento quantitativo da variabilidade térmica na casa de vegetação o que pode ser aplicado em diversas atividades agrícolas a serem desenvolvidas no interior da estrutura. A proposta é que a rede desenvolvida seja de fácil implementação e manuseio, com baixo custo, e que use técnicas computacionais eficientes a fim de permitir a sua fácil adaptação a diferentes necessidades das pesquisas. As redes de sensores sem fios dependem fundamentalmente de estruturas chamadas de nós de sensoriamento, que são responsáveis pelas medições de um parâmetro físico e também pela troca de informações via rádio. No presente e trabalho, o nó de sensoriamento desenvolvido é constituído pelo módulo de rádio XBee Pro S2B; por um módulo de processamento Arduino Nano e por sensores de temperatura modelo LM35. O processador de cada nó de sensoriamento da rede desenvolvida executa um programa que faz a captura dos dados dos sensores de temperatura e os enviam por rádio à um computador onde existe um software que também foi desenvolvido no presente trabalho com o objetivo de receber, separar e gravar os dados de uma rede de sensores sem fio para o monitoramento térmico em casas de vegetação. Cada nó de sensoriamento possui capacidade de ser conectado a até 8 sensores LM35. Na análise térmica, foram distribuídos dois nós de sensoriamento e um total de 15 sensores distribuídos sistematicamente no interior de uma casa de vegetação do tipo teto em arco com dimensões de 8 X 16 metros localizada em Garça – SP. Os sensores foram corrigidos e instalados numa altura de 1,70 metros avaliando o comportamento, variação, e a variabilidade espacial da temperatura do ar no interior da estrutura. Foi avaliado também a distribuição espacial da evapotranspiração de referência utilizando a metodologia proposta por Hargreaves-Samani, que leva em consideração os valores de temperatura diária e radiação solar no topo da atmosfera. A avaliação dos dados mostra que o comportamento da temperatura do ar no interior da casa de vegetação sofreu variações significativas tanto em termos espaciais quanto temporais, evidenciando que o microclima neste ambiente é dinâmico, podendo modificar conforme a localização do sensor e hora do dia, sendo que as maiores variações térmicas ocorreram no período que varia das 8:00 às 14:00 horas. Com esta análise também é possível fazer um cálculo da evapotranspiração no interior da casa de vegetação, o que compõe no sistema desenvolvido uma ferramenta eficaz para a irrigação de precisão. A análise dos dados permite concluir que o sistema desenvolvido atendeu de maneira satisfatória o objetivo proposto, sendo uma importante ferramenta no monitoramento de parâmetros físicos à distância e em tempo real. O emprego desta tecnologia facilita a aquisição de dados e a tomada de decisão em cultivos agrícolas. / This work presents the use of computer technology applied in agricultural systems, which involves aspects of software and hardware for thermal monitoring inside a greenhouse. It includes detailed analyses of the thermal variability in the greenhouse, which can be used in various agricultural activities implemented within the structure. The work also includes de design of a wireless sensor network with main features are easy implementation, low cost, and efficient use of computational techniques to allow easy adaptation to new different needs of research. Wireless sensor networks depend of a structure called sensor node, which are responsible for measuring a physical parameter and by wireless information exchange. In this work, the sensing node was designed with a radio module XBee Pro S2B; an Arduino Nano by a processing module; and the LM35 temperature sensor. The sensor nodes processor runs a program that makes the capture of data from temperature sensors and sends them by radio to a computer where a software which was also developed in this work and aim to receive, separate and record data from a wireless sensor network for monitoring the air temperature inside greenhouses. Each sensor node has the ability to be connected to up to eight LM35 sensors. In greenhouse thermal analysis, they were distributed in two sensing nodes connected to 15 sensors systematically distributed into the greenhouse with dimensions of 8 x 16 meters located in Garça – SP, Brazil. The sensors were fixed and installed at a height of 1.70 meters evaluating the behavior variation and spatial variation of the air temperature inside the structure. It was also evaluated the spatial distribution of reference evapotranspiration using the methodology proposed by Hargreaves-Samani, which takes into account the daily temperatures and solar radiation in the top of the atmosphere. The temperature data analyses shows that the air temperature presents significant variations in spatial and temporal terms, showing that the microclimate in this environment is dynamic and can change as the sensor location and time of day with the greatest temperature changes occurred in the period ranging from 8:00AM to 2:00PM. This analysis is also possible to make a calculation of evapotranspiration inside the greenhouse, which makes up the system developed an effective tool for precision irrigation. The data analysis shows that the system developed satisfactorily met the proposed objective, being an important tool in monitoring physical parameters remotely and in real time. The use of this technology facilitates data acquisition and decision making in agricultural crops.

The objective of the dissertation is to develop simplified analytical models for typical linear-motion and rotary-motion energy-conversion systems under active DC excitation without tedious numerical-simulation effort, and provide practical implementation of the models in optimal-design and thermal-protection aspects. The model of a vacuum automatic circuit recloser (a typical linear-motion system under DC excitation) is first developed in the form of a non-linear discontinuous eighth-order dynamic system. The model is then used to simulate the transient mechanical and electromagnetic performance during the opening and closing movements of the recloser. Such a model is not found in the literature. Although the model is based on certain simplifying assumptions, the result is validated by high-speed-camera measurements. In addition, the impact of key design variables is explored, based on which an improved recloser design is proposed, and helps to optimize capital and production costs without degrading performance. Further analytical investigation is carried out in modeling an inverter-fed induction motor (IM) (a typical rotary-motion system) with active DC injection. The IM is closed-loop controlled via two popular motor-control algorithms, namely, the direct-torque-control (DTC) algorithm and field-oriented-control (FOC) algorithm. Quantitative relationships between the changes of various machine variables during the active DC excitation are provided in the theoretical analysis. The developed DC-injection model is further simplified for practical implementation. The developed IM model under DC injection results in practical ways to excite a proper amount of DC current directly or indirectly into IM stator windings via different closed-loop motor-control algorithms. In a DTC motor-drive system, the modeling work makes it possible to excite the DC current indirectly inside the motor by superimposing a stator-flux-linkage-bias command in the flux-control loop or a torque-ripple command in the torque-control loop. The proposed flux-linkage-injection and torque-injection methods are the first novel efforts to implement the DC-signal-injection method in a DTC motor-drive system. In addition, the analysis carried out in a standard FOC drive system brings about an improved DC-current-injection approach: the torque ripple in this method is significantly mitigated compared to all existing DC-injection methods in FOC systems. The proposed DC-injection methods, either in a DTC or an FOC system, lead to a simple, low-cost, accurate, and non-invasive thermal-monitoring scheme for closed-loop-controlled IMs, where the stator temperature is indirectly estimated from stator resistance. Furthermore, considering inverter non-idealities, there is a challenge for a typical inverter drive to accurately estimate the DC component of motor terminal voltages. The existing methods are extended to provide a complete study of the real-time signal-processing technique for both DTC and FOC algorithms, and are finally implemented in a custom-built programmable motor-drive system. The experimental results demonstrate that the proposed technique gives accurate and robust stator-temperature estimation, regardless of the operating conditions and cooling modes. The analytical modeling method for the linear-motion and rotary-motion energy-conversion systems can be further extended to other power devices with similar mechanisms, and implemented in optimal design, control, and thermal-protection areas.

L'utilisation de caméras infrarouges bas coûts pour la surveillance long-terme d'infrastructures est prometteuse grâce aux dernières avancées technologiques du domaine. Une mesure précise de la température des surfaces observées in-situ se heurte au manque de connaissance des propriétés radiatives de la scène. L'utilisation d'une instrumentation multi-capteurs permet d'affiner le modèle de mesure afin d'obtenir une estimation plus précise de la température. A contrario, il est montré qu'il est toujours possible d'exploiter des données climatiques en ligne pour pallier un manque de capteur. Des méthodes bayésiennes d'estimation conjointe d'émissivité et de température sont ensuite développées et comparées aux méthodes de la littérature. Un simulateur d'échanges radiatifs diffus de scènes 3D a été implémenté afin de tester ces différentes méthodes. Ce logiciel utilise l'accélération matérielle de la machine pour réduire les temps de calcul. Les résultats numériques obtenus mettent en perspective une utilisation avancée de la thermographie infrarouge multi-spectrale pour la surveillance de structures. Cette estimation conjointe permet alors d'obtenir un estimé de la température par thermographie infrarouge avec une incertitude connue. / The latest technological improvements in low-cost infrared cameras have brought new opportunities for long-term infrastructures monitoring. The accurate measurement of surfaces' temperatures is facing the lack of knowledge of radiatives properties of the scene. By using multi-sensors instrumentation, the measurement model can be refined to get a better estimate of the temperature. To overcome a lack of sensors instrumentation, it is shown that online and free available climatic data can be used. Then, Bayesian methods to estimate simultaneously the emissivity and temperature have been developed and compared to literature's methods. A radiative exchange simulator of 3D scenes have been developed to compare those different methods on numerical data. This software uses the hardware acceleration as well as a GPGPU approach to reduce the computation time. As a consequence, obtained numerical results emphasized an advanced use of multi-spectral infrared thermography for the monitoring of structures. This simultaneous estimation enables to have an estimate of the temperature by infrared thermography with a known uncertainty.

In dieser Arbeit wird ein Motorschutzsystem vorgestellt, das die Temperaturen in Asynchronmotoren während des Betriebes zuverlässig und sensorarm berechnet und dabei leicht auf andere Motoren übertragbar ist. Neben dem Schutz vor unzulässiger Erwärmung können die auftretenden Wicklungsverluste für eine wirkungsgradoptimale Ansteuerung genauer ermittelt werden. Basis ist ein thermisches 9-Körper-Modell, das die Temperaturverläufe wesentlicher Maschinenteile abbilden kann. Der vorgeschlagene Identifikationsalgorithmus sorgt für eine hohe Übereinstimmung der Temperaturverläufe. Fehler im thermischen Modell oder der Verlustleistungsberechnung können durch die Rückführung eines einzelnen Temperatursensors und eines verbesserten Schätzers der Läuferwicklungstemperatur korrigiert werden. Das Überschreiten definierter Temperaturgrenzen kann mit der vorgeschlagenen Abschaltzeitprognose auch im Fehlerfall frühzeitig erkannt werden.