Aplicações móveis que não podem ser recarregadas durante operação, como sensores biomédicos e aplicações da Internet das Coisas, dependem da extração de energia do próprio meio onde se encontram. Tensões de alimentação típicas são normalmente maiores que as disponiveis por métodos de extração de energia do meio e requerem uma conversão de nivel DC que invariavelmente resulta em perdas proporcionais ao fator de conversão. Consequentemente, aplicações projetadas para tensões de alimentação mais próximas da tensão nominal da fonte melhora a eficiência energética. Entretanto, topologias de circuitos elétricos para tensões típicas de alimentação sao impróprias para tensões extremamente baixas. Neste trabalho foram propostas topologias de amplificadores de saída unipolar e diferencial para tensões de alimentaçãoo na casa de centenas de milivolts. As técnicas propostas se baseiam no uso de pares pseudodiferenciais com terminais de corpo polarizados diretamente para vários propósitos, incluindo rejeição de modo comum e polarização de modo comum de saída e corrente DC. Adicionalmente, um oscilador baseado na mesmas técnicas de polarização foi proposto e projetado para duas classes de aplicações: um oscilador de referência intrinsicamente estável e um oscilador controlado por tensão para conversão analógica-digital com melhor linearidade. / Nomadic applications which cannot be recharged while at operation, such as biomedical sensors and Internet of Things applications, rely on energy harvesting from the environment. Typical supply voltages are usually higher than those achieved by energy harvesting methods and requires DC-DC conversion levels, which invariably results in energy loss proportionally to the step of voltage conversion. Consequently, designing at supply voltages closer to the nominal voltage of the energy source improves power efficiency. However, extremely low supply voltages bring design challenges, as circuit topologies for typical voltages employ techniques not suitable for extremely low supply voltages. In this work, single ended and fully differential amplifier topologies for voltage supplies in the range of few hundreds mV were proposed. The proposed approaches use the pseudo differential pairs with the transistor bulk terminals with forward biasing voltages for several purposes, including common mode rejection, output common mode voltage and DC current biasing. Additionally, a ring oscillator based in the same biasing techniques was proposed and designed for two main classes of applications: an intrinsically stable reference oscillator and a voltage controlled oscillator for analog-digital conversion with linearity improvements.

Made available in DSpace on 2014-06-11T19:28:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-11-16Bitstream added on 2014-06-13T20:58:15Z : No. of bitstreams: 1 silva_jl_me_jabo.pdf: 612702 bytes, checksum: 10eaf81ab013fceaeeadf68e95ced4d8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Gravena Ltda / O objetivo desta pesquisa foi avaliar a eficiência, no controle de psilídeos, pulgão-marrom-dos-citros e minadora-das-folhas e também a seletividade a Pentilia egena, da aplicação terrestre em volume ultra baixo (UBV) em pomar de laranja. Foram realizadas 03 pesquisas, sendo que a primeira pesquisa foi realizada visando avaliar a mortalidade de adultos confinados do psilídeo e seletividade sobre a Pentilia egena na estação de pesquisa da Gravena Ltda em Jaboticabal-SP, a segunda pesquisa foi realizada visando avaliar a mortalidade de ninfas do psilídeo, pulgão-marrom-dos-citros e minadora-das-folhas em ramos novos em citros e a terceira pesquisa foi realizada visando avaliar a mortalidade de adultos confinados do psilídeo, sendo estas duas últimas realizadas na Fazenda Cachoeira do São Lourenço em Matão-SP. O delineamento estatístico adotado foi em blocos casualizados com número variável de tratamentos em cada pesquisa e quatro repetições. A aplicação da primeira pesquisa foi realizada no dia 25 de março de 2010, da segunda no dia 17 de novembro de 2010 e da terceira em 03 de maio de 2011, sendo usados nas pesquisas os seguintes produtos: Boveria bassiana (2,0 kg/ha), lambda- cialotrina (0,4 L/ha), dimetoato (2 L/ha), etofenprox (0,5 L/ha), thiamethoxan (0,2 kg/ha), Imidacloprid + espirotetramate (0,25 L/ha) e imidacloprido (0,4 L/ha) usando o pulverizador Pulsfog de volume ultra baixo (U.B.V.) comparado com o tratamento com imidacloprido (0,4L/ha) usando pulverizador com lanças manuais e de jato transportado. Baseado nos resultados obtidos pode-se concluir que os tratamentos, com volume ultra baixo (UBV), foram eficientes no controle de psilídeos, pulgão-marrom-dos-citros e minadora-das-folhas. Quanto à seletividade as modalidades de aplicação usadas foram classificadas de moderada a altamente tóxicos para as larvas e adultos de P. egena / The purpose of this study was to evaluate the efficiency in the control of psyllids, citrus brown aphids and the citrus leaf-miner, and also the selectivity to Pentilia egena, by using ground application in ultra-low volume (ULV) in orchard orange. Three surveys were conducted, the first survey was conducted to evaluate the mortality of adult psyllids (Diaphorina citri) confined and selectivity on the ladybug (Pentilia egena) at the Research Station of Gravena Jaboticabal Ltda. The second survey was performed to evaluate the mortality of nymphs of the psyllid, the citrus brown aphid, and citrus leaf-miner in citrus and new branches. And, the third survey was conducted to evaluate the mortality of adults confined the psyllid, the latter being held in the Farm St. Lawrence Waterfall. The statistical design used was randomized blocks with variable number of treatments in each study and four replications. The implementation of the first survey was conducted on March 25th, 2010, the second on November 17th, 2010 and the third survey on May 3rd, 2011, being used in research the following products: Boveria bassiana (2.0 kg / ha), lambda-cyhalothrin (0.4 L / ha), dimethoate (2 L / ha), etofenprox (0.5 L / ha), thiamethoxan (0.2 kg / ha), Imidacloprid spirotetramat + (0, 25 L / ha) and imidacloprid (0.4 L / ha) using the sprayer Pulsfog ultra-low volume (ULV) compared to treatment with Imidacloprid (0.4 L / ha) using manual spray booms and jet transport. Based on the results obtained it is concluded that the treatments with ultra-low volume (ULV), were effective in controlling adults and nymphs of psyllids, citrus brown aphid and citrus leaf-miner. The selectivity of the used application methods was classified as moderate (M) to high (A) toxic to the larvae and adults of P.egena

abstract: Modern day deep sub-micron SOC architectures often demand very low supply noise levels. As supply voltage decreases with decreasing deep sub-micron gate length, noise on the power supply starts playing a dominant role in noise-sensitive analog blocks, especially high precision ADC, PLL, and RF SOC's. Most handheld and portable applications and highly sensitive medical instrumentation circuits tend to use low noise regulators as on-chip or on board power supply. Nonlinearities associated with LNA's, mixers and oscillators up-convert low frequency noise with the signal band. Specifically, synthesizer and TCXO phase noise, LNA and mixer noise figure, and adjacent channel power ratios of the PA are heavily influenced by the supply noise and ripple. This poses a stringent requirement on a very low noise power supply with high accuracy and fast transient response. Low Dropout (LDO) regulators are preferred over switching regulators for these applications due to their attractive low noise and low ripple features. LDO's shield sensitive blocks from high frequency fluctuations on the power supply while providing high accuracy, fast response supply regulation. This research focuses on developing innovative techniques to reduce the noise of any generic wideband LDO, stable with or without load capacitor. The proposed techniques include Switched RC Filtering to reduce the Bandgap Reference noise, Current Mode Chopping to reduce the Error Amplifier noise & MOS-R based RC filter to reduce the noise due to bias current. The residual chopping ripple was reduced using a Switched Capacitor notch filter. Using these techniques, the integrated noise of a wideband LDO was brought down to 15µV in the integration band of 10Hz to 100kHz. These techniques can be integrated into any generic LDO without any significant area overhead. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2014

Analisa-se no presente trabalho o problema das medidas de relaxação dielétrica a U.B.F. (Ultra Baixa Frequência). Propõe-se um modelo de ponte para tais medidas capaz de varrer o intervalo 10-3 Hz-10Hz, baseada na medida de fase conforme a discussão original de Van Turnhout e colaboradores. Analisa-se também os principais problemas experimentais com tal equipamento de U.B.F. e descreve-se a sua construção e funcionamento. Analisa-se também o modelo teórico de correlação entre medidas de U.B.F. e descarga de eletreto com correntes termo-estimulado. Em particular calculamos uma correção para a expressão integral dado por Van Turnhout e colaboradores que leva em conta a influência da energia de ativação na correlação entre as duas técnicas. Tal conversão é significante para valores da energia de ativação menor que 0,5eV e que ocorrem experimentalmente com frequência / In the present work we investigate the problem of U.L.F. (Ultra Low Frequency) dielectric relaxation. An experimental model is proposed for a bridge covering the range of 10-3Hz-10Hz, based on phase shift measurements originally proposed by Van Turhout and collaborators. We also analyze the main experimental problems with such U.L. F. measurements and describe its construction and performance. We have also investigated the theoretical correlation between U.L.F. dielectric relaxation and electret thermal stimulated currents. We calculate in particular, a correction for the integral expression given by Turnhout and collaborators that takes into account the value of the activation energy in the relation between the two techniques. The correction is important for values of the activation energy below 0,5eV, which occur frequently in dielectric relaxation processes

No presente trabalho descreve-se: a determinação da permitividade dielétrica complexa através de medidas de fase; a aplicação de técnicas de correlação e análise em séries de Fourier, para a determinação da fase, amplitude, qualidade e deformação do sinal atrasado; os circuitos eletrônicos do medidor de fase e do oscilador de U.B.F. programável; a programação desenvolvida em FORTRAN IV e MACRO-ASSEMBLER para o computador PDP 11/45, utilizado para operar o medidor de fase e o oscilador de U.B.F. / In the present work we describe: the determination of the complex dielectric permittivity by phase shift measurements; the application of correlation and Fourier series analyses to determine the phase shift, amplitude, quality and deformation of the shifted signal; the designed electronic hardware of the phase meter and programmb1e ultra-low frequency oscillator; the developed software written in FORTRAN IV and MACRO- ASSEMBLER for PDP 11/45, to operate the phase meter

Background: The total fertility rate (TFR) in South Korea has fallen below 1.3 since 2001. The role of the rapid shift toward a late-childbearing pattern in driving Korean fertility decline to this ultra-low level has been little explored until now. Objective: We provide an in-depth analysis of period fertility trends by birth order in South Korea from 1981 to 2015, when the period TFR fell from 2.57 to extremely low levels. Methods: We combine census and birth registration data to estimate period and cohort fertility indicators by birth order. We compare changes in conventional TFR with tempo- and parity-adjusted total fertility rate (TFRp*) and their birth-order-specific components. Results: The tempo effect linked to the shift toward delayed childbearing has had a strong and persistent negative influence on period TFRs in South Korea since the early 1980s. Without the shift to later childbearing, period fertility rates in South Korea would consistently stay higher and decline more gradually, reaching a threshold of very low fertility, 1.5, only in 2014. The postponement of childbearing and the resulting tempo effect were strongest in the early 2000s, when Korean TFR reached the lowest levels. More recently, Korean fertility has been characterized by a diminishing tempo effect and falling first and second birth rates. This trend marks a break with the previous pattern of almost universal fertility and a strong two-child family model. Contribution: Our study demonstrates the importance of the tempo effect in explaining the shift to ultra-low fertility in South Korea and in East Asia.

Nowadays, integrated circuits (IC) are mostly implemented using Complementary Metal Oxide Semiconductor (CMOS) transistor technology. This technology has allowed the chip industry to shrink transistors and thus increase the device density, circuit complexity, operation speed, and computation power of the ICs. However, in recent years, the scaling of transistor has faced multiple roadblocks, which will eventually lead the scaling to an end as it approaches physical and economic limits. The dominance of sub-threshold leakage, which slows down the scaling of threshold voltage VTH and the supply voltage VDD, has resulted in high power density on chips. Furthermore, even widely popular solutions such as parallel and multi-core computing have not been able to fully address that problem. These drawbacks have overshadowed the benefits of transistor scaling. With the dawn of Internet of Things (IoT) era, the chip industry needs adjustments towards ultra-low-power circuits and systems. In this thesis, energy-efficient Micro-/Nano-electromechanical (M/NEM) relays are introduced, their non-leaking property and abrupt switch ON/OFF characteristics are studied, and designs and applications in the implementation of ultra-low-power integrated circuits and systems are explored. The proposed designs compose of core building blocks for any functional microprocessor, for instance, fundamental logic gates; arithmetic adder circuits; sequential latch and flip-flop circuits; input/output (I/O) interface data converters, including an analog-to-digital converter (ADC), and a digital-to-analog converter (DAC); system-level power management DC-DC converters and energy management power gating scheme. Another contribution of this thesis is the study of device non-ideality and variations in terms of functionality of circuits. We have thoroughly investigated energy-efficient approximate computing with non-ideal transistors and relays for the next generation of ultra-low-power VLSI systems.

In the range of 25°C - 80°C (ultra-low grade heat), a large quantity of waste heat from various processes is available unused. Special alloys made of nickel and titanium, so-called Shape Memory Alloys (SMA), could be an alternative technology to Organic Rankine Cycles to make this energy usable in the low power range. The 'THEAsmart 2' research project is therefore investigating the service life and energy lifecycle of this material to test the benefits of shape memory alloys in energy recovery and the efficiency levels that can be achieved. To this end, a demonstration prototype is being built that converts thermal energy into rotary motion. The next step is to link the demonstration prototype with a conventional fluid pump to create an SMA fluid pump that is driven by the thermal energy of the fluid to be pumped. The advantage of such a pump would be that it would be energy-independent, i.e. it would be operated solely by the thermal energy of the fluid without an electrical connection. Furthermore, such a pump could contribute to energy savings if it is used in cooling circuits in which the thermal energy of the fluid is the waste product from another process. In this case, it replaces an electric pump and utilizes the 'waste product' heat. The aim of the project is to investigate how and whether coil springs made of shape memory alloy are suitable for energy recovery. This is considered via the energy lifecycle: if more energy is required to manufacture a spring than this spring can convert kinetic energy from thermal energy in its lifecycle, then its use for energy recovery does not make sense in principle. As a secondary result of this research, statements about the efficiency of shape memory alloy coil springs and statements about their service life are expected.

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