No description available.

No description available.

Since the early 80s, the computer industry has undergone great expansion. Processors are becoming faster and more powerful. Power management issues in computing systems are becoming more complex and challenging. An evolution began when the high-performance Pentium processor was driven by a non-standard, less-than-5V power supply, instead of drawing its power from the 5V plane on the system board. A so-called Voltage Regulator Module (VRM), is put close to the processor in order to provide the power as quickly as possible. Nowadays, for desktop and workstation applications, VRM input voltage has moved to the 12V output of the silver box. In the meantime, microprocessors will run at very low voltage (below 1V), will consume up to 100A of current, and will have dynamics of about 400A/us. This work presents an investigation of three 12V VRM topologies: the synchronous buck converter, the tapped-inductor buck converter and the active-clamp couple-buck converter. The limitations of today¡¯s synchronous buck approach are identified. The extreme duty cycle of the current topology makes it difficult to design an efficient VRM with decent transient response. The tapped-inductor buck and the active-clamp couple-buck converters are discussed as solutions. The transient response and efficiency of each type of converter are compared. Ripple cancellation is also addressed. The analytical and experimental results are presented: The tapped-inductor buck can improve the efficiency, but suffers a voltage spike, which nullifies its candidacy; the active-clamp couple-buck converter can improve the efficiency while maintaining good transient response, and it is therefore a good candidate for 12V VRMs. / Master of Science

The explosive growth in wireless communications has led to an increased demand for wireless products that are cheaper, smaller, and lower power. Recently there has been an increased interest in using CMOS, a traditional digital and low frequency analog IC technology, to implement RF components such as mixers, voltage controlled oscillators (VCOs), and low noise amplifiers (LNAs). Future mass-market RF links, such as BlueTooth, will require the potentially low-cost single-chip solutions that CMOS can provide. In order for such single-chip solutions to be realized, RF circuits must be designed that can operate in the presence of noisy digital circuitry. The voltage controlled oscillator (VCO), an important building block for RF systems, is particularly sensitive when exposed to an electrically noisy environment. In addition, CMOS implementations of VCOs have been hampered by the lack of high-quality integrated inductors. This thesis focuses on the design of a fully integrated 2.5 GHz LC CMOS VCO. The circuit is intended as a vehicle for future mixed RF/digital noise characterization. The circuit was implemented in a 0.35 μm single poly, 4 metal, 3.3 V, CMOS process available through MOSIS. The oscillator uses a complementary negative transconductance topology. This oscillator circuit is analyzed as a negative-resistance oscillator. Monolithic inductors are designed using full-wave electromagnetic field solver software. The design of an "inversion-mode" MOS (I-MOS) tuning varactor is presented, along with a discussion of the effects of varactor nonlinearity on VCO performance. I-MOS varactors are shown to have substantially improved tuning range (and tuning curve linearity) over conventional MOS varactors. Practical issues pertaining to CMOS VCO circuit design, layout, and testing are also discussed. The characterization of the VCO and the integrated passives is presented. The VCO achieves a best-case phase noise of -106.7 dBc/Hz at 100 kHz offset from a center frequency of 2.73 GHz. The tuning range is 425 MHz (17%). The circuit consumes 9 mA from a 3.3 V supply. This represents excellent performance for CMOS oscillator designs reported at this frequency. Finally, several recommendations for improvements in oscillator performance and characterization are discussed. / Master of Science

Over the recent years many people have been trying to reduce the size and weight of magnetic components and thus the overall system [ 19 ]. One attempt at this is to increase the switching frequency of the system. However, this attempt has its limitations due to increased device switching losses. Device limitations usually confine this frequency to lower value than is desired. An effective approach, reducing the size and weight is to use the planar magnetics for possible integration with the power circuit and thus eliminating the associated interconnections. Planar magnetics uses the printed circuit board as the windings. This will allow the magnetic component to be implemented into the circuit. The integration of the magnetic components and power circuit will decrease the number of connections, reduce the height, and ensure the parasitic repeatability. Having external connections can cause problems in the system. In this case the system must carry a large amount of current. The connections can cause heating from resistance and inductance of the connection. The planar approach also will decrease the height of the system. This is because the planar magnetic cores have a higher surface area with a decreased height. This can reduce the height of the system by 25 %- 50 % [ 19 ]. The parasitic repeatability is also a very important factor. In many cases the typology relies on the parasitic elements for energy storage. Since, the parasitic elements are mainly a result from the geometry of the system; and the planar system has the windings made from the printed circuit board, the parasitic elements will be very consistent through the manufacturing process. For topologies that rely on the parasitic elements for soft switching, the planar design can incorporate parasitic elements with the leakage components for the soft-switching requirement. This thesis redefines the conventional term of leakage inductance as the sum of a set of lumped parasitic inductances and the transformer leakage inductance for the integrated planar magnetics and inverter power circuitry. For the conventional non-integrated transformer, either planar or non-planar, the leakage inductance is defined between two terminals of the transformer. However, for the integrated planar magnetics, the new lumped parasitic and leakage inductance should include the inverter switch and dc bus interconnections. The transformer was first designed using a closed-form solution for a known geometry with different copper thickness. The calculated leakage inductance was then verified with finite element analysis and the impedance analyzer measurement. It was found that the theoretical calculation and the finite element analysis results agreed very well, but the measurement was more than one order of magnitude higher. This prompted the study of interconnect parasitics. With geometrical structure and proper termination and lumping, a set of parasitic inductances were defined, and the results were verified with measurements of both impedance analyzer and phase-shifted modulated full-bridge inverter testing. In addition to parasitic inductance analysis, the flux distribution and associated thermal performance of the planar structure were also studied with finite element analysis. The resulting plots of flux distribution and temperature profile indicate the key locations of mechanical mounting and heat sinking. Overall the thesis covers essential design considerations in electrical, mechanical, and thermal aspects for the planar magnetics integration. / Master of Science

Baigiamajame magistro darbe atlikta daugiainduktorės elektros pavaros valdymo būdų analizė. Pateikiami tiesiaeigio asinchroninio variklio statinių charakteristikų skaičiavimai. Sudaryti daugiainduktorės elektros pavaros kompiuteriniai modeliai: fazinėje koordinačių sistemoje ir x, y koordinačių sistemoje. Tiriamojoje dalyje pateiktos daugiainduktorės elektros pavaros jėgos, pagreičio, greičio, kelio, srovės dinaminės charakteristikos, kai induktoriai maitinami iš pastovios įtampos ir dažnio elektros tinklo. Taip pat pateikiamos jėgos, pagreičio, greičio, kelio, srovės dinaminės charakteristikos, kai induktoriai maitinami iš skirtingos įtampos ir dažnio elektros tinklo. Remiantis gautais rezultatais baigiamojo darbo pabaigoje suformuluotos išvados ir pasiūlymai. Prieduose pateikiami TAV statinių charakteristikų skaičiavimo rezultatai, kompiuterinio modelio programa. Darbą sudaro 8 dalys: įvadas, literatūros apžvalga, tyrimo tikslas ir uždaviniai, teorinė dalis, tiriamoji dalis, išvados ir pasiūlymai, literatūra ir kiti šaltiniai, priedai. Darbo apimtis – 64 p. teksto be priedų, 65 iliustr., 2 lentelės 33 bibliografiniai šaltiniai. / In the Final Master Thesis analyzed control methods of multi inductor linear electric drive . Provided the linear induction motor operating characteristics calculations. Moreover, two types of computer models are created: in phase coordinate system and x, y coordinate system. At the research part presented multi inductor electric drive force, acceleration, speed, road, current dynamic characteristics, when inductors are powered by a constant voltage and frequency of the mains. Also presents force, acceleration, speed, road, current dynamic characteristics, when inductors are powered from different voltage and frequency of the mains. Based on the results of the thesis provides conclusions and recommendations. At the annexes part presented calculation results of linear electric motor static characteristics and application of a computer model. The Thesis consists of 8 sections: introduction, literature review, research purpose and objectives, the theoretical part, research part, conclusions and suggestions, references and other sources and annexes. The Thesis includes: 64 pages of the text without annexes, 65 figures, 2 tables, 33 references.

This theses analyzes Cuk converter, that is one of the dc to dc switching converters. For continuous inductor current mode and discontinuous inductor current mode, stedy state operation is analysied. Characteristic parameters are determined. Through State Space Averge Models, Small Signal Models are obtained. Parasitic Resistance effects on steady state and small signal models are determined. Efficency of the switching converter is derived. Open loop transfer functions for continous and discontinuous inductor curret mode are obtained. Parmeters for small signal behaviour is determined and stability is analysied. Parasitic resistance effects on transfer functions is determined. Therotecial analysis are verified with a simulations of designed converter.

No description available.

Orientador: Adriano Sakai Okamoto / Resumo: Uma das principias doenças transmitida por alimento é a salmonelose, causada pela bactéria Salmonella spp., ela está presente em vários aviários, e com o aumento da produção avícola, se disseminou nos aviários, tornando-se um problema pertinente e de grande importância na saúde pública e animal. Com isso medidas de controle foram instituídas, entre elas o uso de antimicrobiano, causando diversas discussões, principalmente em relação a resistência bacteriana á antimicrobianos utilizados na medicina humana, onde medidas alternativas estão sendo desenvolvidas para evitar o uso dos antimicrobianos. Dessa forma o objetivo do projeto foi avaliar a capacidade dos Lactobacillus spp., isolados na inibição da Salmonella Heidelberg (SH), pelo mecanismo de quorum sensing in vitro e in vivo. Foram colhidos de suabes cloacal de frangos de corte que passaram por provas fenotípica e molecular. Esses isolados foram submetidos ao teste de inibição em placa para avaliar a capacidade de inibição da SH. Em seguida foram produzidos os filtrados, a partir dos Lactobacillus sp. (ATCC), separadamente, com contato com a SH. Esses isolados foram cultivados com os filtrados, separadamente e em seguida submetidos novamente ao teste de inibição em placa. Dessa maneira, foi possível medir e comparar os halos de inibição, para a verificação da ocorrência da comunicação bacteriana entre os Lactobacillus sp. (ATCC) e os isolados. Foi realizada a análise estatística selecionando um Lactobacillus spp. isolado d... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: One of the main food-borne diseases is salmonellosis, caused by the bacterium Salmonella spp., It is present in several aviaries, and with the increase of poultry production, it has spread in aviaries, becoming a relevant problem and of great importance in health public and animal. With this, control measures were instituted, including the use of antimicrobial, causing several discussions, mainly regarding bacterial resistance to antimicrobials used in human medicine, where alternative measures are being developed to avoid the use of antimicrobials. Thus, the objective of the project was to evaluate the ability of Lactobacillus spp., isolated in the inhibition of Salmonella Heidelberg (SH), by in vitro and in vivo quorum sensing mechanism. They were harvested from cloacal swabs of chickens that underwent phenotypic and molecular tests. These isolates were subjected to plaque inhibition test to assess the inhibitory capacity of SH. Filtrates were then produced from Lactobacillus sp. (ATCC), separately, with SH. These isolates were cultured with the filtrates separately and then replate inhibited. In this way, it was possible to measure and compare inhibition halos to verify the occurrence of bacterial communication between Lactobacillus sp. (ATCC) and the isolates. Statistical analysis was performed by selecting a Lactobacillus spp. isolated from chickens and a filtrate which obtained better results in the in vitro test. The in vivo test was divided into four treatments, Lacto... (Complete abstract click electronic access below) / Mestre

Objetivando reduzir o manejo em protocolos de inseminação artificial em tempo fixo (IATF), quatro experimentos foram realizados para avaliar a dinâmica folicular (Experimentos 1A e 1B) e a taxa de concepção (TC; Experimentos 2, 3 e 4) em vacas de corte tratadas com Cipionato (CE) ou Benzoato (BE) de estradiol como indutores da ovulação. No Experimento 1A, 51 animais receberam 2mg de BE e um dispositivo intravaginal de progesterona (DIB) novo no D0. No D8, os animais foram distribuídos entre quatro tratamentos (G-BE8, G-BE8,5, G-BE9 e G-CE8). Neste dia, o dispositivo foi removido, 0,530mg de Cloprostenol e 300UI de eCG foram administrados [manhã (M) no G-BE8, G-CE8 e G-BE9; tarde (T) no G-BE8,5]. As vacas do G-CE8 receberam 1,0mg de CE, as do G-BE8 e G-BE8,5 receberam 1,0mg de BE na retirada do DIB, e aquelas do G-BE9 receberam 1,0mg de BE 24 horas após. Análises ultra-sonográficas foram realizadas a cada 12 horas, da retirada do dispositivo até a ovulação. Foram utilizados os PROC GLM e GLIMMIX do SAS para análise estatística. Nos experimentos não foram observadas interações. Os resultados para G-BE8, G-CE8, G-BE8,5 e G-BE9 foram, respectivamente: diâmetro do folículo ovulatório (FO;11,9±0,4b; 14,3±0,4a; 12,3±0,4b; e 13,3±0,abmm; P=0,01), taxa de ovulação (TO;100%; 90,0%; 100% e 91,7%; P=0,99] e intervalo retirada/ovulação (IRO;58,3±2,1b; 72,0±2,0a; 57,6±1,3b e 72,0±0,0ah; p<0,001). No Experimento 1B (n=35), foi utilizado arranjo fatorial 3x3 [números de uso do DIB vs protocolos de indução da ovulação (PIO)]. No D0, os animais foram divididos em três grupos [DIB novo (DIBN), usado 8 (DIB8) e 16 dias (DIB16)]. Na retirada do DIB, os animais foram redistribuídos para os PIOs descritos no Experimento 1A (exceto G-BE8). Os resultados para G-CE8, G-BE8,5 e G-BE9 foram, respectivamente: FO (14,0±0,6; 13,8±0,6 e 13,6±0,5mm; P=0,88), TO [81,8%; 83,3% e 83,3%; P=0,93] e IRO (72,0±2,0a; 59,6±1,6b e 73,2±1,2ah; p<0,01). Os resultados para DIBN, DIB8 e DIB16 foram respectivamente: FO (13,8±0,7; 13,5±0,6 e 13,9±0,5mm; P=0,99), TO [90,9%; 83,3% e 75,0%; P=0,93] e IRO (74,4±1,6a; 72,0±0,0ab e 68,0±2,0bh; P=0,02). No Experimento 2, 584 animais foram alocados em fatorial 3x2 [PIO (CE8, BE8,5 e BE9) e período de IATF (IATF-M ou IATF-T)], utilizando DIBN. Não houve diferença na TC: CE8 (57,5%), BE9 (59,9%) e BE8,5 (49,5%; P=0,09) e IATF M (56,6%) ou T (54,8%; P=0,66). No Experimento 3, 521 vacas foram divididas como no Experimento 2, porém com DIB8. Não houve diferença na TC nos PIOs: CE8 (47,3%), BE9 (53,3%) e BE8,5 (55,2%; P=0,10). Porém, houve diferença na TC para IATF-M (60,7%) ou IATF-T (48,3%; P=0,01). No Experimento 4, 1192 vacas foram distribuídas em fatorial 2x3x2 (DIBN e DIB8; BE8,5, BE9 e CE8; IATF-M e IATF-T). Não houve diferença na TC para: IATF-M (64,6%) ou IATF-T (59,5%; P=0,06) e PIOs; CE8 (65,8%), BE9 (61,8%) e BE8,5 (58,6%; P=0,12). Entretanto, houve diferença na TC (P=0,04) para uso do DIB; DIBN (65,0%) e DIB8 (59,4%). Esses resultados indicam que os PIOs apresentam mesma eficiência. Com DIB8, a IATF-T apresentou menor TC e o uso de DIB8 resultou em menor TC do que DIBN. / Aiming to minimize the number of handling during protocols for fixed-time artificial insemination (FTAI), four experiments were performed to evaluate the follicular dynamics (Experiments 1A and 1B) and conception rate (CR; Experiments 2, 3 e 4) in beef cows treated with estradiol cypionate (EC) or benzoate (EB) as ovulation inducers. In Experiment 1A, 51 animals received 2mg of EB and a new intravaginal progesterone device (DIB) on D0. On D8, animals were assigned into four treatments (G-EB8, G-EB8.5, G-EB9 and G-EC8). On the same day, the device was removed, 0.530mg of Cloprostenol and 300UI of eCG were administered [morning (AM) - G-EB8, G-EC8 and G-EB9; afternoon (PM) - G-EB8.5]. Cows of G-EC8 received 1.0mg of EC, while G-EB8 and G-EB8.5 received 1.0mg of EB at DIB removal, and those of G-EB9 received 1.0mg of EB 24h later. Ultrasonography was performed every 12h from DIB removal until ovulation. Statistical analysis was performed using PROC GLM and PROC GLIMMIX (SAS). No interactions were observed between treatments. Results of G-EB8, G-EC8, G-EB8.5 and G-EB9 were, respectively: diameter of ovulatory follicle (OF;11.9±0.4b; 14.3±0.4a; 12.3±0.4b; and 13.3±0.6abmm; P=0.01), ovulation rate (OR; 100%; 90.0%; 100% and 91.7%; P=0.99) and interval between device removal-ovulation (IRO; 58.3±2.1b; 72.0±2.0a; 57.6±1.3b and 72.0±0.0ah; p<0.001). Experiment 1B (n=35) was performed using a fatorial design 3x3 [DIB reutilization and ovulation inducer (OI)]. On D0, animals were allocated into three groups [new DIB (DIBN), used 8 (DIB8) and 16 days (DIB16)]. At DIB removal, animals were reallocated into the same OIs described on Experiment 1A, except by the G-EB8. The results of G-EC8, G-EB8.5 and G-EB9 were, respectively: OF (14.0±0.6; 13.8±0.6 and 13.6±0.5mm; P=0.88), OR [81.8%; 83.3% and 83.3%; P=0.93], and IRO (72.0±2.0a; 59.6±1.6b and 73.2±1.2ah; p<0.01). Results of DIBN, DIB8 and DIB16 were, respectively: OF (13.8±0.7; 13.5±0.6 and 13.9±0.5mm; P=0.99), OR (90.9%; 83.3% and 75.0%; P=0.93), and IRO (74.4±1.6a; 72.0±0.0ab and 68.0±2.0bh; P=0.02). At Experiment 2, 584 animals were allocated into a 3x2 fatorial design [OI (EC8, EB8.5 and EB9) and FTAI period (FTAI-AM or FTAI-PM)], being treated with DIBN. There was no difference on CR: EC8 (57.5%), EB9 (59.9%) and EB8.5 (49.5%; P=0.09) and IATF AM (56.6%) or PM (54.8%; P=0.66). On Experiment 3, 521 cows were allocated into the same experimental design of Experiment 2, however using DIB8. There was no difference on CR between different OIs: EC8 (47.3%), EB9 (53.3%) and EB8.5 (55.2%; P=0.10). However, there was difference on CR between FTAI-AM (60.7%) and FTAI-AM (48.3%; P=0.01). On Experiment 4, 1192 cows assigned into a 2x3x2 fatorial design (DIBN and DIB8; EB8.5, EB9 and C8; FTAI-AM and FTAI-PM). No differences were found on CR between FTAI-AM (64.6%) or FTAI-PM (59.5%; P=0.06), and OIs; EC8 (65.8%), EB9 (61.8%) and EB8.5 (58.6%; P=0.12). Cows treated with DIBN showed higher CR when compared to those treated with DIB8 (65.8 vs. 59.4%, respectively; P=0.04). These results indicate a similar efficiency using different OIs. Using DIB8, the FTAI-PM showed lower CR. Also the protocol using DIB8 resulted in lower CR than using DIBN.