Three novel single-stage electronic ballasts with the advantages of high-power-factor, low current harmonic, high efficiency, and low cost are proposed for rapid-start fluorescent lamps. Included are (1) single-stage high-power-factor electronic ballast with asymmetrical topology, (2) single-stage high- power-factor electronic ballast with symmetrical topology, and (3) single-stage single-switch high-power-factor electronic ballast. The circuit configurations are obtained by integrating the buck-boost power-factor-correction converter into the Class D or the Class E resonant inverter. With simple circuit configuration and less component count, desired circuit performances of high-power-factor and high efficiency are realized. The control methods of pulse-width-modulation (PWM) with asymmetrical and symmetrical approaches are utilized for the three presented ballasts. The buck-boost conversion stage is operated at discontinuous current mode (DCM) to achieve nearly unity power factor at a fixed switching frequency. With carefully designed circuit parameters, the power switches can exhibit either zero-voltage switching-on (ZVS) or zero-current switching-on (ZCS). As a result, high circuit efficiency can be ensured. Design equations are derived and computer analyses are performed based on the lamp¡¦s equivalent resistance model and fundamental approximation. Accordingly, design guidelines for determining circuit parameters are provided. Prototypes of the three proposed circuits designed for a T8-36W lamp, two series-connected T9-40W lamps and a PL-27W lamp are built and tested to verify the computer simulations and analytical predictions.

Active water management uses real-time information to continually respond and adjust to water management needs and situations. To support active water management, the Texas Commission on Environmental Quality (TCEQ) needs tools to access and understand data and to apply that understanding to operational decisions. The work described herein addresses two objectives in providing decision-support for the TCEQ: (1) methods for including environmental pulse flow regulations in water rights documents, and (2) improved ease of access to information needed for TCEQ watermaster operations, particularly in times of drought. A Pulse Scaling Method for calculating the trigger flow rate, volume, and duration of flow pulses, using known characteristics at a reference location A, that are appropriate at a target location B (with unknown characteristics) was developed from three key relationships found in the written environmental flow regulations for fifteen locations in the Trinity, San Jacinto, Sabine, and Neches basins. Applying the method and analyzing the results shows that the predictions are statistically consistent with original regulations. A Common Operating Picture is a layered web-map allowing simultaneous access to one or more spatially-related datasets that TCEQ watermaster staff need to consider in decision-making. By its very nature as a dynamic map with associated time series, the Common Operating Picture presents data as information in a way that can support water resource management and decision-making. The project is currently in the pilot stage, with a number of data sources included and an interface available, but with additional work planned and further testing needed before larger-scale implementation. / text

This work is concerned with the design, development and performance evaluation of an inertance Pulse Tube Cryocooler (PTC). The main components of a PTC are the compressor, regenerator, pulse tube and inertance tube coupled to a reservoir. The inertance tube is a key component that affects the pressure and mass flow and phase shift between them and hence the performance. In conjunction with the compressor, it also plays a strong role in determining the frequency of operation. The PTC is designed based on system level numerical models (SAGE and DeltaE), component level thermo-acoustic models (DeltaE) of inertance tube and regenerator and experimental data of earlier fabricated Stirling coolers. As a starting point, an inertance tube with a diameter of 3 mm and 3.1 m long was chosen through component level analysis that provides phase shift of around 50 degrees at a pressure ratio of 1.1 for an acoustic power of about 4 W (in order to achieve 1 W of net cooling at 80 K) at 25 bar mean pressure and 60 Hz. From this inertance tube geometry, an estimate of the mass flow rate at the cold heat exchanger is obtained. Based on this mass flow rate, the initial dimensions of the pulse tube and regenerator are arrived at. A parametric study using system level model is carried out to obtain the maximum COP by varying inertance tube length and regenerator diameter. A flexure bearing compressor consisting of moving coil linear motor coupled to a piston is designed for the above cold head. Based on the above design considerations, the PTC compressor and cold head are fabricated and assembled. The PTC is charged with helium at mean pressure of 25 bar and instrumented with pressure and position transducers, temperature sensors and a skin-bonded heater for simulating the heat load on the cold head. Experimental data for the PTC were obtained with two different inertance tube lengths for different frequencies of operation. The cold head temperature exhibited a minimum with respect to the frequency. This optimum frequency shifts towards lower frequency with increased length of the inertance tube. The experimental data clearly shows that with different inertance tube lengths the optimum frequency locates itself for obtaining zero phase shift at the middle of the regenerator. It is observed that the optimum frequency is closely linked to the natural frequency of the pressure wave in the inertance tube suggesting a standing wave within the inertance tube with the pressure node at the reservoir. Thus the inertance tube is found to be analogous to a quarter wave resonator in a thermo-acoustic device. It may thus be possible to pre-fix an operating frequency for a given PTC cold head by choosing an inertance tube length close to quarter wave resonator length. This study has given insights on the phase shift between pressure and mass flow rate governed by the inertance tube and the connection between the optimum and natural frequencies which can be used for better design of PTCs.

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T13:39:10Z No. of bitstreams: 0 / Made available in DSpace on 2016-06-22T13:39:10Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:11/00769-7

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2014. / The application of digital control techniques has become dominant in power electronics owing to several advantages they present, when compared to analogue solutions. Their development is based on the use of microprocessors and microcontrollers, such as Application Specific Integrated Circuit (ASIC), Digital signal processors (DSP), Field Programmable Gate Arrays (FPGA), or a combination of these devices. This thesis presents an investigation of a soft-core based FPGA control system as a solution for power electronic applications. The aim was the development and implementation of a conversion controller, which purpose is to supply control inputs in the form of digital Pulse Width Modulation (PWM) signals, to a number of power electronic applications, such as single half and full bridge DC-DC converters, three phase and multicell inverters. The PWM control technique is achieved via their power semiconductor switching devices. These PWM control signals are necessary for the high frequency conversion of an analog input voltage (AC, DC or unregulated) to an analog output voltage of another level (AC or DC). This was intended to be achieved by exploiting and combining the advantages that FPGA and embedded processors provide such as high reconfigurability and multipurpose ability. This controller’s digital outputs, namely PWM switching signals, can be directly delivered to an analog signal amplification circuit to create an adequate voltage level before being processed by the converters’ switches.

Orientador: Jose Antenor Pomilio / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-06T14:09:31Z (GMT). No. of bitstreams: 1 Rondani_Bruno_M.pdf: 5870538 bytes, checksum: 69f2b2bd154400cd5b620b87a2c4fe8c (MD5) Previous issue date: 2005 / Resumo: Descreve-se neste trabalho o desenvolvimento de uma topologia de modulador de pulso estado-sólido e a linha de retardo modular, para aplicação em transmissores pulsados de alta potência que utilizem válvulas de microondas magnetron empregadas comumente em radares de trajetografia, meteorologia e controle de tráfego aéreo. A pesquisa abrange o projeto, desenvolvimento e construção de um modulador de pulso destinado à modernização do transmissor do radar de trajetografia Bearn do Centro de Lançamentos de Foguetes da Barreira do Inferno, Natal -RN. O equipamento desenvolvido fornece pulsos de até 37,5kV e 60A em três modos de transmissão, a saber: monopulso longo, monopulso curto e bipulso. No modo monopulso longo, a largura de pulso é de 1,7µs e nos outros dois modos, 0,85µs. A taxa de repetição dos pulsos é de 585,5Hz. A unidade de modulação de pulso consiste de oito módulos de chaveamento em paralelo, conectados ao primário de um transformador de pulso de razão 1:50. Cada módulo contém dois trechos de linha de retardo e duas chaves estado-sólido e é capaz de gerar pulsos de até 790V e 390A nos diferentes modos de operação. A alimentação da linha de retardo é feita através de um circuito de carga composto por um indutor de alimentação e um circuito de Clipper. O indutor de alimentação faz com que a tensão de carga na linha seja dobrada em relação à tensão contínua presente na saída da fonte de alimentação de entrada, devido à ressonância série criada entre esse indutor e a capacitância total das linhas de retardo. O circuito de Clipper garante a regulação de tensão pulso a pulso e a proteção do modulador contra surto de sobre-corrente na carga e sobre-tensão nas linhas de retardo. Esta topologia foi desenvolvida para melhorar a confiabilidade e facilitar a manutenção dos transmissores de radar com a implementação do conceito de degradação suave (graceful degradation) do modulador de pulso / Abstract: This work describes the development of a modular line-type solid-state pulse modulator topology to be applied in magnetron pulsed power radar transmitters, commonly found on tracking, weather and air traffic management radars. This research includes the design, development and assembling of a pulsed modulator for the Barreira do Inferno Launching Center (CLBI, Natal-RN) Bearn tracking radar upgrade program. The equipment developed provides pulses of 37.5 KV and 60 A in three transmission modes: single long pulse, single short pulse and bipulse. In the single long pulse the pulse width is 1.7 µs and in the other modes 0.85 µs. The pulse repetition frequency is of 585.5Hz. The modulator unit is composed by eight switching modules connected in parallel with the primary windings of a 1:50 ratio pulse transformer. Each module has two pulse-forming network and two IGBT switches and it is capable of handling 790 V and 390 A in the three operational modes. An inductor and a Clipper circuit implement the pulse-forming network charging. The charging inductor allows charging the pulse-forming network with twice the supply voltage since there is a resonance with the total modulator capacitance. The Clipper circuit assures the pulse-to-pulse charging voltage regulation and protects the modulator against load over-current and over-voltage charging. This topology was developed to improve reliability and maintainability of radar transmitters by implementing the graceful degradation (soft failure mode) in the pulse modulator / Mestrado / Sistemas e Controle de Energia / Mestre em Engenharia Elétrica

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T13:39:10Z No. of bitstreams: 0 / Made available in DSpace on 2016-06-22T13:39:10Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A emissão de poluentes em megacidades e áreas industriais pode ter fortes impactos no clima e na saúde. Nos últimos anos tem sido crescente a preocupação com emissões atmosféricas contendo partículas nanométricas, cuja presença, juntamente com compostos orgânicos voláteis, óxidos de nitrogênio e outros, pode resultar na formação de uma série de substâncias gasosas poluentes e na formação de aerossóis. Medições mais precisas da concentração e distribuição de tamanho de fuligem são importantes, não só do ponto de vista ambiental, mas também para a saúde humana. O objetivo deste trabalho foi determinar a distribuição de tamanho de partículas na chaminé de uma refinaria em Cubatão. Para isso foi utilizada uma abordagem baseada nos métodos de inversão, tradicionalmente usados para calcular parâmetros de aerossóis atmosféricos, ao contexto dos aerossóis de tochas industriais. Os resultados se mostraram consistentes com a literatura científica, sendo possível determinar alguns parâmetros da distribuição do tamanho de partículas provenientes da chama de uma tocha industrial utilizando um sistema lidar de três comprimentos de onda com um nível de discrepância aceitável. Um estudo do expoente de Angström foi realizado com o objetivo de validar o algoritmo de inversão desenvolvido neste trabalho. Os resultados deste estudo mostraram que os dados experimentais corroboram com as curvas teóricas e, portanto, o algoritmo pode ser utilizado como ferramenta para a medição de emissões atmosféricas provenientes de tochas industriais. O desenvolvimento deste projeto representará um passo importante, não somente do ponto de vista tecnológico, mas principalmente como recurso para tratar de problemas de emissões que futuramente poderão surgir, dentre as medidas voltadas ao controle de mudanças climáticas. / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:11/00769-7

Vaginal photoplethysmography was utilized in combination with standardized sleep-recording procedures to investigate changes in vaginal pulse amplitude (VPA) during both waking and sleeping conditions in low- and high-arousability females (n = 10 per group), as classified by the Sexual Arousability Inventory. Based upon previous research, it was predicted that both groups would exhibit similar mean levels of VPA during waking exposure to erotic stimuli and during various stages of sleep. Despite hypothesized physiological similarities between groups, the low-arousability group was expected to subjectively report less arousal during the waking erotic conditions.

The thesis addresses the conceptual design and implementation of the switched-mode power supply having the adjustable dc voltage output up to 25V and current output up to 15A. The half-bridge topology is used for this supply. Design features and quantities are simulated in PSpice and Micro-Cap simulation tools. The thesis covers the simulation results, assembly data and the results measured on the implemented functional sample.

This paper deals with the effect of the MR pulse sequences on the temperature of the measured object. The theoretical part is dedicated to basic principle of magnetic resonance, the selected pulse sequences and risks that are connected with MRI. There is also described the draft of the testing phantom and information about the measurement and record of temperature during MR measurement. In the experimental part the effect of RF coils, pulse sequences and parameters of pulse sequences are tested on drafted phantom with experimental MR device located at the Institut of Scientific Instruments of the AS CR in Brno. These findings are then tested on live laboratory mouse. All results are analyzed and used as default data for developed simulation program.