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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

Hybrid powertrains analysis for ship propulsion using energy storage. / Análise de alimentação híbrida para propulsão de navios usando sistemas de armazenamento de energia.

Giovani Giulio Tristão Thibes Vieira 05 September 2018 (has links)
The ship emission already occupy the eighth position in the world biggest emitters ranking. This happens because the ship operations have a huge demand variation therefore in order to reduce the ship emissions is required an efficient operation of the generators. This work aims at integrating advanced storage systems into the operation of diesel generators. The variation of the operation point has a direct interference on the emissions and on the diesel consumption, this variation is allowed through the frequency and voltage control. The use of lithium batteries for various operation points of the generators is analyzed. The use of an energy storage system allowed the operation of the generators in a better operation point therefore there was a reduction in diesel consumption and in CO2 emissions when the diesel generators. The main result of this work could also shed light in the operation of isolated power systems equipped with advanced storage systems and diesel generators. / As emissões dos navios já ocupam a oitava posição entre os países com maior emissão no mundo. Isso pode ser explicado pelo fato de que as operações dos navios têm uma grande variação de demanda de potência, com isso a operação inteligente dos geradores a diesel é fundamental para a redução das emissões. A abordagem desenvolvida nesse trabalho integra o uso de sistemas de armazenamento avançados na operação dos geradores a diesel. A variação do ponto de operação dos geradores a diesel interfere diretamente no consumo e nas emissões, essa variação só é possível por meio do controle de frequência e tensão providos pelo sistema de armazenamento de energia. Nesse trabalho foram analisados o uso de baterias de lítio para diferentes pontos de operação do gerador a diesel. O uso das baterias possibilitou a operação dos geradores num melhor ponto de carga com isso houve uma redução das emissões e do consumo de combustível. Os resultados encontrados nesse trabalho podem ser extrapolados qualitativamente para outros sistemas de potência offshore, como plataformas de petróleo e de perfuração, que operem com sistemas de baterias avançadas e geradores a diesel.
272

Biochemical and pharmacological studies of morphine-6-glucuronide and related compounds

Martin, Jason Lewis January 1994 (has links)
Morphine-6-glucuronide is a minor metabolite. representing 5% of an administered dose of morphine. The metabolite has analgesic activity exceeding that of morphine and may contribute to analgesia following morphine administration. The aims of the study were to attempt to identify the reasons behind the improved activity of morphine-6-glucuronide over the parent compound and to examine a series of 6-substituted compounds, based on 6-substituted benzoate esters, as potential mimics of morphine-6-glucuronide. Morphine-6-glucuronide was seen to have similar affinity to morphine at l1-opioid receptors as assessed by ligand-binding assays in mouse brain homogenates. However a three-fold improved affinity at S-opioid receptor binding sites was observed and a ten-fold reduction in affinity at K-opioid sites. Using in vitro bioassay systems the glucuronide showed a two-fold improved potency over morphine in both the guinea-pig ileum and the mouse vas deferens preparations. Following in vivo (s.c.) administration in the mouse the glucuronide was seen to be equipotent with morphine in the tail-flick test, but was of much longer duration, lasting up to 9 hours. Exvivo binding assays confirmed that morphine-like material was still present in the central nervous system six hours after administration of the glucuronide, but was not observed at a similar time after morphine administration. Activity was retained if the hydroxyl groups of the sugar moiety of the glucuronide were protected as esters. In contrast the more prevalent morphine metabolite morphine-3-glucuronide was inactive in all in vitro and in vivo tests used and did not antagonise morphine in vitro or in vivo. A group of 3-substituted derivatives containing saturated and unsaturated substituents did show affinity for opioid receptors but no agonist activity of the compounds could be demonstrated in vitro. A series of synthetic 6-substituted compounds showed a variety of affinities for, and agonist potencies at, opioid receptors, though low affinity at Kopioid receptors was a general finding. For example, morphine-6- nitrobenzoate was l1-opioid receptor preferring, while morphine-6- phthalate had improved O-opioid receptor affinity and acted via Il-opioid receptors in the mouse vas deferens and in vivo. However the compounds were weaker than morphine and the duration of action in vivo was shorter than morphine-6-glucuronide. The conclusions from these studies are that morphine-6-glucuronide and morphine have similar in vitro affinities at the l1-receptor, although morphine-6-glucuronide has somewhat improved binding affinity for Il receptor sites, it has less affinity for K receptor sites. Pharmacokinetic reasons are probably responsible for the improved activity and duration of action of morphine-6-glucuronide over morphine. None of the synthetic compounds examined are potentially useful as direct mimics of the glucuronide because morphine-6-glucuronide is more potent and has a longer duration of action than the synthetic derivatives, though alteration at the 6-position of the morphine nucleus can lead to dramatic changes in selectivity and potency of ligands for the differing opioid receptors.
273

O índice de Poincaré-Hopf e generalizações no caso singular / The Poincaré-Hopf index and generalizations in singular case

Dalbelo, Thaís Maria 25 February 2011 (has links)
Neste trabalho,estudamos o índice de Poincaré-Hopf, definido para singularidades isoladas de campos de vetores sobre variedades diferenciáveis. Além disso, investigamos algumas definições de índices de campos de vetores definido sem variedades singulares, como o índice de Schwartz e o índice GSV. Estudaremos estes invariantes no caso específico em que (V; 0) é um germe de uma interseção completa com singularidade isolada na origem / In this work, we study thePoincaré-Hopf index, defined for isolated singularities of vector fields on manifolds. Moreover, we investigate some definitions of indices of vector fields defined on singular varieties, as the Schwartz index and the GSV index. We study these invariants in the case where (V; 0) is a germ of a complete intersection with an isolated singularity at the origin
274

Studies on affective disorders in rural Ethiopia

Fekadu, Abebaw January 2010 (has links)
Background Affective disorders are poorly defined and studied in sub-Saharan Africa despite their substantial public health impact. Objectives Overall objective: To describe the epidemiology of selected affective disorders in rural Ethiopia. Specific objectives 1. To describe the validity and utility of the concept of minor depressive disorder (mD). 2. To describe the manifestation, prevalence and the short-term clinical and functional course and outcome of bipolar disorder. Subjects and methods Population: Zay community residents (age ≥16), and residents of Butajira (ages 15-49), in Southern Ethiopia. Study design: Population-based cross-sectional and longitudinal studies Case identification: For the identification of cases with bipolar disorder, a two stage process was employed. An initial screen used key informants and interview with the Composite International Diagnostic Interview (CIDI) to identify cases with probable bipolar disorder. A second confirmatory diagnostic assessment stage employed the Schedules for Clinical Assessment in Neuropsychiatry (SCAN). For the identification of cases with mD, data from the CIDI was used. Follow-up: 312 cases with bipolar disorder from Butajira were followed up for a mean of 2.5 years (ranging 1-4 years) through monthly clinical assessments and annual symptom and functional ratings. Results The CIDI was administered to 1714 adults among the Zay and to 68, 378 adults among the Butajira residents. The prevalence of mD among the Zay and Butajira was 20.5% and 2.2% respectively. Up to 80% of cases with mD had used services for their symptoms, while a third to a half of cases had thought about self harm. Up to a sixth of cases had attempted suicide. Age, marital status, education and somatic symptoms were independently associated with mD. The prevalence of bipolar disorder among the Zay was 1.8%. During a 2.5-year follow-up of 312 cases with bipolar disorder from Butajira, 65.9% relapsed (47.8% manic, 44.3% depressive and 7.7% mixed episodes) while 31.1% experienced persistent illness. Female gender predicted depressive relapse whereas male gender predicted manic relapse. Only being on psychotropic medication predicted remission (OR=3.42; 95% CI=1.82, 6.45). Disability was much worse among bipolar patients than in the general population and was predicted by symptom se3verity. Conclusions This is the largest study on mD and bipolar disorder in Africa. mD appears to have potential clinical utility in this setting given its association with service use and risk. The identified risk factors for mD also suggest potential aetiological continuity with major depression. The relatively high prevalence of bipolar disorder among the Zay may be related to genetic predisposition perhaps mediated through a founder effect, but other factors need exploring. In relation to the outcome of bipolar disorder, this study indicates that, contrary to previous assumptions, the course of bipolar disorder is characterised by both manic and depressive relapses in a relatively proportionate fashion. Bipolar disorder also leads to significant levels of disability. This is the only prospective outcome study of bipolar disorder in Africa where cases were monitored systematically at short assessment intervals. Therefore, findings are likely to be more robust than previous reports.
275

Mechanisms for Cadmium Lumen-to-Cell Transport by the Luminal Membrane of the Rabbit Proximal Tubule

Wang, Yanhua 04 May 2007 (has links)
The lumen-to-cell transport, cellular accumulation, and toxicity of ionic cadmium (109Cd2+) and cadmium-cysteine conjugate (Cys-S-109Cd-S-Cys) were studied in isolated perfused S2 segments of the proximal tubule of the rabbit kidney. All perfusion solutions were HEPES buffered and contained 3H-L-glucose which functioned as a volume and leak marker along with 250 nM FD & C Green dye as a vital dye. When ionic cadmium, 0.73µM Cd2+, or 0.73µM cadmium-cysteine conjugate (Cys-S-109Cd-S-Cys) containing solution was perfused through the lumen of the tubule there was no visual evidence of toxicity such as blebbing of the luminal membrane, cellular vital dye uptake, and cellular swelling. Ionic Cd2+ transport was temperature dependent (87% reduction at 22°C and 100% at 11°C) and inhibited by FeCl2 (42% reduction at 10µM) and ZnCl2 (48% reduction at 20µM), and high Ca2+ concentrations (27% reduction at 1.95mM and 69% at 2.6mM). The ionic Cd2+ transport was not affected by verapamil and diltiazem. The cadmium conjugate (Cys-S-Cd-S-Cys) transport was also temperature dependent (76% reduction at 22°C and 100% at 11°C) and inhibited by the amino acids L-cystine and L-arginine (55% and 50% respectively), stimulated by L-methionine (56%), but not affected by L-aspartate, L-glutamate and Gly-Sar. 2, 3-Dimercaptopropane-1-Sulfonate (DMPS) co-perfused with Cd2+ decreased absorption of 20µM Cd2+ (39% reduction at 30 µM and 94.6% reduction at 200 µM), while DMPS added to the bathing solution has no effect on the luminal transport of Cd2+. DMPS co-perfused with 20 µM Cys-S-Cd-S-Cys substantially reduced Cd2+ transport (62% reduction at 30 µM). We conclude that cadmium can be transported at the luminal membrane of the S2 segment of the proximal tubule by multiple mechanisms, depending on the form which it is presented to membrane. Ionic cadmium appears to be transported by iron (DCT1), zinc (ZTL1) transporters and some kind of calcium-selective channel while cadmium conjugate of L-cysteine appears to be transported by L-cystine transporters (system b0+). Dipeptide transporter is not involved in the transport of cadmium. DMPS appears to be a chelator for cadmium.
276

Reliability and cost/worth evaluation of generating systems utilizing wind and solar energy

Gen, Ba 29 August 2005
The utilization of renewable energy resources such as wind and solar energy for electric power supply has received considerable attention in recent years due to adverse environmental impacts and fuel cost escalation associated with conventional generation. At the present time, wind and/or solar energy sources are utilized to generate electric power in many applications. Wind and solar energy will become important sources for power generation in the future because of their environmental, social and economic benefits, together with public support and government incentives. <p>The wind and sunlight are, however, unstable and variable energy sources, and behave far differently than conventional sources. Energy storage systems are, therefore, often required to smooth the fluctuating nature of the energy conversion system especially in small isolated applications. The research work presented in this thesis is focused on the development and application of reliability and economic benefits assessment associated with incorporating wind energy, solar energy and energy storage in power generating systems. A probabilistic approach using sequential Monte Carlo simulation was employed in this research and a number of analyses were conducted with regards to the adequacy and economic assessment of generation systems containing wind energy, solar energy and energy storage. The evaluation models and techniques incorporate risk index distributions and different operating strategies associated with diesel generation in small isolated systems. Deterministic and probabilistic techniques are combined in this thesis using a system well-being approach to provide useful adequacy indices for small isolated systems that include renewable energy and energy storage. The concepts presented and examples illustrated in this thesis will help power system planners and utility managers to assess the reliability and economic benefits of utilizing wind energy conversion systems, solar energy conversion systems and energy storage in electric power systems and provide useful input to the managerial decision process.
277

Reliability and cost/worth evaluation of generating systems utilizing wind and solar energy

Gen, Ba 29 August 2005 (has links)
The utilization of renewable energy resources such as wind and solar energy for electric power supply has received considerable attention in recent years due to adverse environmental impacts and fuel cost escalation associated with conventional generation. At the present time, wind and/or solar energy sources are utilized to generate electric power in many applications. Wind and solar energy will become important sources for power generation in the future because of their environmental, social and economic benefits, together with public support and government incentives. <p>The wind and sunlight are, however, unstable and variable energy sources, and behave far differently than conventional sources. Energy storage systems are, therefore, often required to smooth the fluctuating nature of the energy conversion system especially in small isolated applications. The research work presented in this thesis is focused on the development and application of reliability and economic benefits assessment associated with incorporating wind energy, solar energy and energy storage in power generating systems. A probabilistic approach using sequential Monte Carlo simulation was employed in this research and a number of analyses were conducted with regards to the adequacy and economic assessment of generation systems containing wind energy, solar energy and energy storage. The evaluation models and techniques incorporate risk index distributions and different operating strategies associated with diesel generation in small isolated systems. Deterministic and probabilistic techniques are combined in this thesis using a system well-being approach to provide useful adequacy indices for small isolated systems that include renewable energy and energy storage. The concepts presented and examples illustrated in this thesis will help power system planners and utility managers to assess the reliability and economic benefits of utilizing wind energy conversion systems, solar energy conversion systems and energy storage in electric power systems and provide useful input to the managerial decision process.
278

Implementation of a Dual-Active-Bridge Bidirectional Isolated DC to DC Converter in Home Area Network

Lo, Sheng-Chieh 13 September 2012 (has links)
In recent years, smart gird has received much attention, and many researchers have devoted to home area network (HAN) to improve the efficiency of grid. This thesis proposes a bidirectional isolated DC-DC converter (Dual Active Bridge, DAB) with phase shift control to implement the concept of HAN. Li+Fe battery is used as storage device of the converter, and a bidirectional communication between Laboratory Virtual Instrumentation Engineering Workbench (LabVIEW) and Digital Signal Processor (DSP) is realized by CAN-bus. By setting the current command given by LabVIEW system, the converter is able to charge the Li+Fe battery with constant current and constant voltage method as well as discharge the Li+Fe battery with constant current. Operation principle of the converter and the associated loss are presented.
279

A Novel Music Algorithm Based Electromagnetic Target Recognition Method In Resonance Region For The Classification Of Single And Multiple Targets

Secmen, Mustafa 01 February 2008 (has links) (PDF)
This thesis presents a novel aspect and polarization invariant electromagnetic target recognition technique in resonance region based on use of MUSIC algorithm for the extraction of natural-resonance related target features. In the suggested method, the feature patterns called &ldquo / MUSIC Spectrum Matrices (MSMs)&rdquo / are constructed for each candidate target at each reference aspect angle using targets&rsquo / scattered data at different late-time intervals. These individual MSMs correspond to maps of targets&rsquo / natural-resonance related power distributions. All these patterns are first used to obtain optimal late-time interval for classifier design and a &ldquo / Fused MUSIC Spectrum Matrix (FMSM)&rdquo / is generated over this interval for each target by superposing MSMs. The resulting FMSMs include more complete information for target resonances and are almost insensitive to aspect and polarization. In case of multiple target recognition, the relative locations of a multi-target group and separation distance between targets are also important factors. Therefore, MSM features are computed for each multi-target group at each &ldquo / reference aspect/topology&rdquo / combination to determine the optimum late-time interval. The FMSM feature of a given multi-target group is obtained by the superposition of all these aspect and topology dependent MSMs. In both single and multiple target recognition cases, the resulting FMSM power patterns are main target features of the designed classifier to be used during real-time decisions. At decision phase, the unknown test target is classified either as one of the candidate targets or as an alien target by comparing correlation coefficients computed between MSM of test signal and FMSM of each candidate target.
280

Design Of An Educational Purpose Multifunctional Dc/dc Converter Board

Baglan, Fuat Onur 01 August 2008 (has links) (PDF)
In this thesis a multifunctional DC/DC converter board will be developed for utilization as an educational experiment set in the switched-mode power conversion laboratory of power electronic courses. The board has a generic power-pole structure allowing for easy configuration of various power converter topologies and includes buck, boost, buck-boost, flyback, and forward converter topologies. All the converters can be operated in the open-loop control mode with a switching frequency range of 30-100 kHz and a maximum output power of 20 W. Also the buck converter can be operated in voltage mode control and the buck-boost converter can be operated in peak-current-mode control for the purpose of demonstrating the closed loop control performance of DC/DC converters. The designed board allows for experimentation on the DC/DC converters to observe the macroscopic (steadystate/ dynamic, PWM cycle and low frequency) and microscopic (switching dynamic) behavior of the converters. In the experiments both such characteristics can be clearly observed such that students at basic learning level (involving only the macroscopic behavior), and students at advanced learning level (additionally involving the parasitic effects) can benefit from the experiments. The thesis reviews the switch mode conversion principles, gives the board design and proceeds with the experiments illustrating the capabilities of the experimental system.

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