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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.
61

Novos desenvolvimentos na localização de faltas em sistemas de distribuição de energia elétrica fundamentada na impedância

Salim, Rodrigo Hartstein January 2008 (has links)
Apesar do crescente desenvolvimento das metodologias de localização de faltas fundamentadas na impedância para sistemas de distribuição de energia elétrica nas últimas décadas, alguns aspectos ainda carecem de progressos, especialmente frente à crescente necessidade de aumento da qualidade da energia elétrica entregue aos consumidores. Um destes aspectos diz respeito à consideração da capacitância das linhas de distribuição, efeito nunca dantes considerado para este fim pelas metodologias baseadas em impedância aparente. Assim sendo, o presente trabalho apresenta novos desenvolvimentos relativos à consideração do efeito capacitivo para as metodologias de localização de faltas fundamentadas na impedância para sistemas de distribuição de energia elétrica. O principal desenvolvimento apresentado é um novo equacionamento para fins de localização de faltas, que torna necessária a apresentação de outro desenvolvimento, o de um algoritmo de localização de faltas que considere a capacitância da linha. As novas equações são apresentadas para todos os tipos de faltas e constituem-se de equações polinomiais de segunda ordem em relação ao local da falta. De forma a entender a resposta destas equações frente a diferentes casos de faltas e determinar qual a solução fisicamente correta destas equações, as mesmas são analisadas sob três pontos de vista, a saber, matemático, físico, e numérico. Inicialmente estas equações são analisadas de forma analítica considerandose faltas em um mesmo local, mas com resistências diferentes. Posteriormente a mesma análise é realizada numericamente através de simulações computacionais. Os desenvolvimentos propostos são também submetidos a testes de faltas, simuladas computacionalmente em um sistema sem laterais ou cargas intermediárias. Os resultados obtidos são comparados frente a resultados obtidos também para outras metodologias que constituem atualmente o estado da arte em localização de faltas fundamentada na impedância para sistemas de distribuição de energia elétrica. Através destes resultados é possível mostrar a grande influência que o efeito capacitivo possui nestas metodologias, mesmo em sistemas aéreos de distribuição, e elucidar as grandes melhorias obtidas através dos desenvolvimentos propostos. / Despite the increasing development of impedance-based fault location techniques for electric power distribution systems in the last decades, some aspects still require to progress, especially with the increasing necessity of power quality enhancement. One of these aspects regards to the distribution line shunt admittance consideration, effect that has never been considered before by the impedance-based fault location methods for power distribution systems. In this way, this work presents further improvements regarding the capacitive effect consideration for impedance-based fault location methods for power distribution systems. The main improvement presented is the development of new fault location equations, which yield the necessity of another improvement, a modified fault location algorithm that also considers the line shunt admittance. The new equations are presented for all fault types and are constituted by second-order polynomials in relation to the fault location. In order to understand the response from these equations regarding different fault situations and determine which solution is the physically feasible one, these equations are analyzed from three different points of view, i.e., mathematical, physical, and numerical. First, the developed equations are analytically analyzed considering faults in one location with different fault resistances. After, the same analysis is numerically carried out through computational simulations. The performance of the proposed improvements are also evaluated through computational simulations of faults in a power distribution system without laterals or intermediate loads. The obtained results are compared with results from the current state-of-the-art impedance-based fault location methodologies for power distribution systems. Through these results it is possible to show the great effect that the line shunt admittance, even in aerial distribution systems, has on the existing fault location methodologies and also the great improvements brought by the proposed developments.
62

Seismic source properties of slow and fast earthquakes in the Guerrero seismic gap, Mexico / メキシコ・ゲレロ地震空白域周辺の地震とスロー地震の震源特性

Plata Martínez, Raymundo Omar 24 September 2021 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第23454号 / 理博第4748号 / 新制||理||1681(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)准教授 伊藤 喜宏, 准教授 宮澤 理稔, 教授 久家 慶子 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
63

A Survey of Water Losses – The Case of The Ramotswa Village in Botswana.

Kholoma, Ezekiel January 2011 (has links)
Water-related problems in major populated areas of Botswana continue to grow unabated. At the heart of these problems are escalating demands, dwindling water supplies, deteriorating infrastructures and water losses. Several reports indicate that water managers in this area have been engrossed more on increasing supplies and less on demand management and conservation. The latest construction of the Dikgatlhong Dam is an example of the measures taken to supplement the existing water sources. However, much of the supplied water continues to be lost from the distribution systems of some of the villages. The highest losses have been reported in the Ramotswa village. This study surveyed the causes of the water losses and factors affecting their developments and frequencies. The study’s view was that reducing those losses would improve the system efficiency and save more water for supplies. The data for the study was acquired from reports of earlier studies, field visits and oral interviews administered on the water managers and consumers. Leakages from the Boatle-Ramotswa supply pipeline, service pipes, reservoirs and valves, unmetered fire-fighting consumptions and water theft were identified to be the main sources of the losses. The utility’s loss control activities were inefficient due to the lack of measures for identifying and reducing each individual loss. The study proposed that all the different uses and losses into which the system input volume goes should be identified and measured and measures for controlling each of them be designed and instituted.
64

Apparent Diffusion Coefficient as an MR Imaging Biomarker of Low-Risk Ductal Carcinoma in Situ: A Pilot Study / 低リスク非浸潤性乳管癌のMRI上のバイオマーカーとしてのみかけの拡散係数 : パイロット研究

Iima, Mami 24 March 2014 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18128号 / 医博第3848号 / 新制||医||1001(附属図書館) / 30986 / 京都大学大学院医学研究科医学専攻 / (主査)教授 福山 秀直, 教授 戸井 雅和, 教授 平岡 眞寛 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DGAM
65

Diagnostic Accuracy of Apparent Diffusion Coefficient and 123I-Metaiodobenzylguanidine for Differentiation of Multiple System Atrophy and Parkinson's Disease / 多系統萎縮症とパーキンソン病の鑑別診断におけるMRI拡散係数とMIBG心筋シンチの有用性

Umemura, Atsushi 25 May 2015 (has links)
京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第12945号 / 論医博第2097号 / 新制||医||1010(附属図書館) / 32204 / (主査)教授 髙橋 良輔, 教授 富樫 かおり, 教授 髙橋 淳 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM
66

Pretreatment Mean Apparent Diffusion Coefficient Is Significantly Correlated With Event-Free Survival in Patients With International Federation of Gynecology and Obstetrics Stage Ib to IIIb Cervical Cancer / FIGO進行期分類IB-IIIB期子宮頸癌の予後予測因子としての治療前ADC値の有用性の検討

Himoto, Yuki 23 March 2016 (has links)
This is a non-final version of an article published in final form in International Journal of Gynecological Cancer. Final publication is available at http://journals.lww.com/ijgc/Pages/default.aspx / 京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19557号 / 医博第4064号 / 新制||医||1013(附属図書館) / 32593 / 京都大学大学院医学研究科医学専攻 / (主査)教授 武藤 学, 教授 平岡 眞寛, 教授 古川 壽亮 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
67

Temporal impulse response function of the visual system estimated from ocular following responses in humans / 追従眼球運動から推測されたヒト視覚系の時間インパルス応答関数

Ohnishi, Yusuke 23 March 2017 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20259号 / 医博第4218号 / 新制||医||1020(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 渡邉 大, 教授 林 康紀, 教授 髙橋 良輔 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
68

Apparent Competition with Bromus tectorum Through Pyrenophora semeniperda Reduces Establishment of Native Grasses

Merrill, Katherine Temus 16 March 2011 (has links) (PDF)
Contributing to the success of Bromus tectorum in the Intermountain West may be a mechanism called apparent competition, which occurs when one species increases the pressure of a consumer on a second species. This indirect interaction has been documented only a few times in invasive plant systems, and never in a fungal pathosystem. We examined the effects of the invasive annual Bromus tectorum and predation by the seed pathogen Pyrenophora semeniperda on seedling emergence and survival for two native grasses (Pseudoroegneria spicata and Elymus elymoides), by manipulating B. tectorum densities and P. semeniperda inoculum loads in randomized plots. Identical field studies were conducted in Skull Valley, Utah (xeric site) and Sprague, Washington (mesic site). The addition of inoculum decreased emergence of native grass seedlings at both sites and increased the amount of unemerged native seeds that were killed by P. semeniperda. Higher densities of B. tectorum decreased native grass survival at the mesic site and increased survival at the xeric site probably due to the beneficial effects of B. tectorum litter on soil moisture. At both sites, there were more B. tectorum seeds found in the seed banks in plots with high B. tectorum densities than in low-density plots. This indicates an increase in available prey for P. semeniperda. There was a much lower level of infection in B. tectorum seed bank seeds at the mesic site than at the xeric site. The high level of ungerminated native seeds killed by background levels of P. semeniperda, combined with the increase in available prey for the fungus in high-density B. tectorum plots, shows that apparent competition may play a role, along with direct competition, in the success of B. tectorum. This interaction is important to consider when dealing with control of B. tectorum.
69

Physically Effective Fiber Threshold, Apparent Digestibility, and Novel Fecal Microbiome Identification of the Leopard tortoise (Stigmochelys pardalis)

Modica, Breanna Paige 01 September 2016 (has links) (PDF)
Particle size distribution of diet, feces, and change from diet to feces, as well as apparent digestibility (aDig, %) of selected nutrients, and novel fecal microbiome identification of mature female leopard tortoises (Stigmochelys pardalis, n = 16) fed exclusively one of three, nutritionally complete, pelleted diets were evaluated in a blind, complete randomized design study. Two diets included insoluble fiber (powdered cellulose) consisting of either 2.0 mm or 0.2 mm length. Insoluble fiber provides nutritional and physical benefits to both the animal host and the microorganisms that inhabit the gastrointestinal tract. Insoluble fiber length was used as a means of evaluating a physically effective fiber (peNDF) definition for hindgut-fermenting vertebrates. Numerical trends of each diet particle size distribution indicated a greater amount of particle recovery on the 2.0 mm sieve for the 2.0 mm diet, and a greater particle recovery on the 0.125 mm sieve for the 0.2 mm diet, both as expected based on the added fiber lengths. Fecal particle size distributions were not different between diets, however, distributions of the change in particle size from diet to feces were different between diets. Similar fecal particle size distributions across diets suggests both cellulose lengths are below the peNDF threshold of the leopard tortoise. Apparent digestibility (aDig, %) of dry matter (DM) and organic matter (OM) was not different based on diet, method, or a diet and method interaction; aDig (%) of neutral detergent fiber (aNDF) and sequential acid detergent fiber (sADF) was different based only on diet. These results suggest that while aDig (%) of OM did not change, the source of OM digestibility shifted, as both aNDF and sADF digestibility increased with the cellulose-added diets compared to the control diet. An increase in insoluble fiber digestibility suggests an "effectiveness" of the cellulose lengths. At both bacterial phyla and genera levels, fecal microbiomes were more similar between tortoises fed the cellulose-added diets versus the control diet, suggesting that the hindgut microbial communities adjusted in the hindgut of the tortoises fed the cellulose-added diets by shifting proportions of microbes, based on their role in the hindgut (i.e., cellulose digestion), to accommodate for the addition of cellulose in the two treatment diets. This may explain the similarity among fecal particle size distributions, and suggests that adaptability of the hindgut microbial communities should be considered when defining peNDF for hindgut-fermenting vertebrates.
70

Evaluation of Cobb MV × Cobb 500 broiler response to various nutrient regimens to maximize performance and economics

Hirai, Rosana 09 August 2019 (has links)
To maximize the economics of a new commercial broiler cross, research on its nutritional specifications is necessary. Study 1 investigated the effects of feeding four amino acid densities (AAD) on performance and yield of Cobb MV × Cobb 500 broilers at d 33 and 36. Data demonstrated a stepwise decrease in feed conversion ratio (FCR) as AAD level increased. Improvements in performance, processing, and economic return were observed when feeding higher AAD levels. Study 2 estimated the digestible lysine (dLys) requirements of Cobb MV × Cobb 500 broilers from d 0-14 and evaluated the impact of varying starter dLys levels on their performance, processing, and economic return during a 42 d grow-out. Data suggested that d 0-14 dLys requirements varied based on broiler response and statistical model. Improvements in overall performance was observed when feeding ≥1.12% dLys during the starter phase. The greatest economic return was associated with feeding starter dLys of 1.20%. Due to the potential interaction between AA and apparent metabolizable energy (AME), Study 3 examined the response of Cobb MV × Cobb 500 to varying dLys and AME levels from d 0-14 on d 0-42 performance and processing. A dLys × AME interaction was observed for d 0-28 FCR and for dLys and AME for early performance parameters. However, this significance was lost by the end of the study. Due to the variation in broiler response to feeding strategies at different ages, Study 4 evaluated the impact of varying dLys and AME levels from d 14-28 on performance and processing of 42-day old Cobb MV × Cobb 500 broilers. Data demonstrated significant dLys × AME interactions for d 14-28 and 14-35 FCR, as well as significances for main effect of dLys and AME for performance and processing (d 42). Feeding grower diets formulated to 1.18% dLys + 3028 kcal/kg AME was the most profitable diet. Overall, this research demonstrates that higher AAD improved broiler performance, especially ≥1.12% starter dLys. Varying dLys and AME during the starter phase did not affect performance at d 42; however, it did when this regimen was exercised during the grower phase.

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