Energy efficiency optimization of electric machines is an important research field and is part of the objectives of several international projects such as the European Commission Climate and Energy package which has set itself a 20% energy savings target by 2020, and was extended for 2030 with higher targets. Therefore, this thesis proposes an efficiency optimization method of the Induction Machine (IM) through the variation of the control parameters. To achieve this goal, the flux in the airgap is modified according to an optimal flux table computed off-line for all possible operating points. The flux table is calculated with the best possible accuracy through an improved dynamic model of the IM, developed in these works. The latter avoids the main drawback of the classic dynamic model, by considering the effect of core losses. The core loss model established by Bertotti is used. It depends on the frequency and the amplitude of the magnetic field. The losses are then represented by a variable resistor, continuously evaluated according to the operating point. The established optimal flux table is a function of the operating conditions in terms of torque and speed. Indeed, the results show that the flux can be optimized for torque values less than about half the rated torque, and that this threshold is influenced by the speed. The proposed optimization method is simulated, then tested for the scalar control and the field-oriented control, in order to show the genericity of the proposed approach. The validation is carried on an experimental test bench for two 5.5 kW induction motors of different efficiency standards (IE2 and IE3). The results obtained show the reduction of the losses in the motor, thus an improvement of the overall efficiency while preserving a satisfactory dynamic behavior. Consequently, the optimization of the energy efficiency is validated for the two control structures and for the two studied motors. In addition to the validation of the simulation results, the proposed approach is compared to existing methods to assess its effectiveness

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15652号 / 工博第3310号 / 新制||工||1500(附属図書館) / 28189 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 小尻 利治, 教授 椎葉 充晴, 教授 角 哲也 / 学位規則第4条第1項該当

Abstract A stripline structure is closed and therefore protected against surrounding EMI and it is easy to bury in multiplayer structures, which offer higher circuit density. This thesis focuses on the evaluation (and verification via actual structures) of the correct simulation of striplines and, as a new aspect, the advantages of using a dual-stripline. Multiple design methods and electromagnetic simulation systems were tested and properties of these are compared. For a reliable design it is still necessary to use at least two tools, at first a very fast tool having excellent circuit parameter optimization methods and then some electromagnetic simulator, which can be used to the complete the realizable layout. That is, because all the electromagnetic simulators suffer from the same limiting factors, the memory capacity of the computer and the unacceptable calculation time. It has been discovered through modelling that the "cat-eye" shape having many more and larger local inaccuracies at the thinned edge areas of the sintered conductor in LTCC structures increases the conductor losses. Therefore it is important to develop new manufacturing methods capable of producing better-shaped conductors. A combination of broadside coupled parallel connected striplines has been tested both in High Temperature Superconducting ( HTS ) and LTCC materials. A two-conductor stripline, a dual stripline, raises the power handling capability of a microwave bandpass HTS filter. In addition, it offers the possibility to use a normal metal protection layer at the surface of the superconductor without degradation of electrical properties, thus increasing the power handling capability even more. The dual stripline solution in LTCC would offer some preferable properties in high power filters only. The shape of the ground plane used for trimming the coupling between resonators was also found to have a remarkable influence on the quality factor of the resonator. A quite narrow ground strip can offer a much better quality factor with the same coupling level than a meshed or continuous ground plane, but it requires accurate design and manufacturing methods. It would help to design filters with lower loss in the passband without compromises in the attenuation outside the passband.

[pt] Neste trabalho analisam-se perdas de calor para as formações adjacentes a reservatórios de petróleo submetidos a métodos térmicos de recuperação, em especial para os métodos de injeção de vapor e combustão in-situ. O cálculo desta perda usualmente utiliza um modelo unidimensional vertical de condução de calor nos estratos adjacentes, desprezando a condução nas direções paralelas ao reservatório. O objetivo do trabalho consiste em avaliar diversos modelos unidimensionais existentes na literatura e desenvolver e utilizar modelos bidimensionais para verificar a validade da hipótese. Verifica-se que para algumas situações de injeção Cíclica de Vapor e Combustão in-situ o modelo uni-dimensional pode levar a diferenças no campo de temperaturas, mas em geral a aproximação é válida. / [en] In this work the calculation of the heat losses to the surrouinding formations in petrolum reservouis submitted to thermal recovery processes is analyzed. Particular attention is given to steam injection an in-situ combustion methods. The heat losses are commonly modeled by the use of a unidimensional conduction equation in the vertical direction, where the longitudinal conduction is neglected. The aim of thus work is to compare some of the existing unidemnsional models and to test the validity of the simplification by the development and use of bidimensional ones. Its is concluded that for some cases of cyclic steam injection and in-situ combustion the unidimensional approach may result in deviations in the temperature profiles, but in general it is valid.

Read the abstract in the section 00front of this document. / Thesis (PhD (Plant Pathology))--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted

DC to DC step-down applications with high input voltage and high voltage conversion ratio operational requirements, such as photovoltaic battery chargers, are subject to high conduction losses, high switching losses and substantial reverse-recovery losses when minority carrier principle diodes are used. The recent introduction of silicon carbide diodes with high breakdown voltages has made possible the elimination of reverse-recovery losses at high voltage levels and as such has sparked interest in their use due to the potential efficiency improvements. This report presents the results of a comprehensive analysis on the use of silicon carbide diodes and their counterparts, ultrafast silicon diodes, in conventional buck converters and isolated current-fed buck converters in high input voltage and high voltage conversion ratio step-down applications. The analysis illustrates both theoretically, with the use of steady-state average models, and experimentally the substantial efficiency benefits of the use of reverse-recovery free silicon carbide diodes in the conventional buck converter and the small but significant improvement in the efficiency of the isolated current-fed buck converter. The improvements of the conventional buck converter paired with silicon carbide diodes are shown to be significant enough to grant the variant the most efficient position for power levels below 1 kW. In addition, the four variants are categorized based on their cost and performance; therefore, providing engineers with a convenient guide to aid their selection of the appropriate converter depending on the operational requirements. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The use of livestock guarding dogs (LGDs) to mitigate farmer-predator conflict in Namibia was evaluated. As farmer-predator conflict has two sides, LGDs were evaluated in terms of livestock production and conservation. The main objectives in terms of livestock production were to document: 1) the perceived ability of LGDs to reduce livestock losses in a cost-effective manner; 2) the farmers’ satisfaction with LGD performance; and 3) factors influencing LGD behaviour. The main objectives in terms of conservation were to record: 1) predator killing by farmers relative to LGD introduction; 2) direct impacts of LGDs on target (damage-causing) species; and 3) the impact of LGDs on non-target species. This evaluation was conducted on LGDs bred by the Cheetah Conservation Fund (CCF) and placed on farms in Namibia. The data were collected during face-to-face interviews with farmers using LGDs. Historical data from the CCF programme were used in conjunction with a complete survey of the farmers in the CCF LGD programme during 2009-2010. In terms of livestock production, 91 percent of the LGDs (n = 65) eliminated or reduced livestock losses. Subsequently, 73 percent of the farmers perceived their LGDs as economically beneficial, although a cost-benefit analysis showed that only 59 percent of the LGDs were cost-effective. Farmers were generally satisfied with the performance of their LGDs. However, farmer satisfaction was more closely linked to good LGD behaviour than the perceived reduction in livestock losses. The most commonly-reported LGD behavioural problems (n = 195) were staying at home rather than accompanying the livestock (21 percent) and chasing wildlife (19 percent). LGD staying home behaviour was linked to a lack of care on subsistence farms, as high quality dog food was not consistently provided. Care for LGDs declined with LGD age on subsistence, but not commercial, farms. In terms of conservation, predator-killing farmers killed fewer individuals in the year since LGD introduction than previously; this result was only significant for black-backed jackal Canis mesomelas. However, 37 LGDs killed jackals, nine killed baboons Papio ursinus, three killed caracals Caracal caracal and one killed a cheetah Acinonyx jubatus (n = 83). Farmers and LGDs combined killed significantly more jackals in the survey year than the same farmers (n = 36) killed before LGD introduction. Conversely, five farmers killed 3.2 ± 2.01 cheetahs each in the year before LGD introduction, whereas LGDs and these farmers combined killed only 0.2 ± 0.2 cheetahs per farm in the survey year. Only 16 LGDs (n = 83) killed non-target species. The high LGD success rate in terms of livestock production was facilitated by livestock husbandry practices in the study area. In terms of conservation, LGDs were more beneficial for apex predators than for mesopredators and had a minor impact on non-target species.

L'étude du coût des inondations passées est essentielle pour permettre aux parties prenantes, publiques et privées, d'améliorer la gestion et la prévention des risques. Les retours d'expérience sur les dommages économiques sont notamment utiles aux gestionnaires de bassin pour justifier leurs mesures de protection ou aux assureurs pour évaluer l'exposition réelle de leurs portefeuilles. Pourtant seuls les événements les plus meurtriers, coûteux ou médiatiques sont étudiés de manière approfondie. Même si elles sont rares, il existe des informations et des données sur des événements moins dommageables, plus locaux et fréquents ; mais elles sont difficiles à exploiter car produites par des acteurs très variés qui communiquent peu entre eux et agissent sur des périmètres différents.L'objectif de cette thèse est de favoriser le partage d'informations entre assureurs et acteurs locaux pour améliorer les connaissances sur les facteurs explicatifs de sinistralité et proposer des pistes d'amélioration dans la prévention des inondations, en exploitant les concepts de périmètres spatio-temporels des événements naturels, l'évaluation des dommages causés par les inondations et les notions d'observation territoriale. / Cost analysis of past flood events is essential for public and private stakeholders to improve the management and risk prevention. For instance, past events lessons learnt allow floodplain managers to justify their preventive measures or insurers to comfort by experience the assessments made on their portfolio's exposure. Yet only the most deadly, costly or dramatic (in the media at least) floods are being studied. Few in number, information and data are available on less damaging events which are more local and frequent, but they are difficult to use because they are produced by a variety of actors who do not communicate with each other and have different scopes of actions.The aim of this PhD work is to promote the sharing of knowledge between public and private stakeholders to better understand the origin of the claims and propose new ways to improve the flood prevention. The research is therefore based on the concept of natural event spatio-temporal scopes, the flood damage assessment and territorial observation.

Domestic sheep farmers in the lower Fraser Valley (L.F.V.) had reported increasing losses of sheep to coyote (Canis latrans) and dog (C. familiaris) predation. The objectives of this study were: (1) to determine if management and geographic factors predispose sheep farms to coyote and dog predation; (2) to assess the relative impact of coyote and dog predation on the L.F.V. sheep population; (3) to record basic attributes of coyote biology (taxonomy, reproduction, food habits, home range, movements, activity patterns, and predatory behaviour); (4) to provide practical and economical recommendations to reduce or prevent coyote and dog predation on sheep in the L.F.V. One hundred and twelve sheep farmers were interviewed over three years, 1979 to 1981. Farms which lost sheep to coyotes characteristically had relatively large flocks (>50 ewes) on large fields (4+ ha), did not confine sheep at night, and either buried or left sheep carcasses exposed. There were no common factors among farms which lost sheep to dogs. Predation accounted for 28.2% of all mortality and 2.4% of the total population sampled. Coyotes killed 69.7% and 74.7% of all ewes and lambs lost to predators. An average of 24.3% of the farms lost sheep to coyotes and dogs each year. However, 55.2% of the farms which lost sheep to coyotes did so in two or three consecutive years compared to 17.4% of farms which lost sheep to dogs. Coyotes in the L.F.V. were similar in most biological aspects studied to other coyote populations in North America. The only exception was that small rodents, primarily Microtus townsendi composed over 70% (scat volume) of their diet, a proportion higher than in other areas. Domestic livestock (mostly poultry carrion) comprised only 4.3% of the diet, sheep only 0.2%. I concluded that in the rural-urban L.F.V. interface, prevention of coyote predation (and secondarily dog predation) on hobby farms is largely a matter of management. The most effective and economical solution is to provide predator-proof enclosures for night confinement of sheep because coyotes were most active at night. This method could be further enhanced by removing livestock carcasses off the farm or by burying and liming them to avoid attracting coyotes to the farm vicinity. / Land and Food Systems, Faculty of / Graduate

Orientador: José Vicente Hallak d'Angelo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-18T13:13:04Z (GMT). No. of bitstreams: 1 Moreira_CintiaCristinaGarcia_M.pdf: 1646345 bytes, checksum: 6924d108b277ad4e1638c59be0e3def6 (MD5) Previous issue date: 2007 / Resumo: A sutura de categute é um material composto basicamente de colágeno, o qual é uma proteína obtida da camada serosa do intestino delgado de bovinos e é facilmente absorvido pelo corpo humano. Devido a esta característica, fios de categute são muito utilizados em vários tipos de cirurgias, como por exemplo: gastrintestinais, amarraduras de vasos na tela subcutânea, cirurgias ginecológicas e urológicas. De fácil manipulação, a sutura de categute, comporta-se como um corpo estranho, desencadeando uma reação inflamatória intensa ao seu redor. O categute possui uma sólida aceitação no mercado de produtos médicos hospitalares. Seu processo de produção ainda apresenta um alto índice de rejeição (cerca de 25%) do material semi-acabado. Deste percentual rejeitado, mais da metade é devido ao aparecimento de manchas no fio. Esta rejeição se dá, num primeiro momento, exclusivamente em função do aspecto visual, uma vez que fios com manchas são tomados como sendo fios defeituosos. Este trabalho teve por finalidade identificar a influência dos defeitos de manchas no material semi-acabado e também no produto final, comparando o desempenho dos fios com e sem manchas. Nesta comparação entre os fios foram realizados testes visuais (aparência); químicos (teor de cromo e de formol); físicos (resistência à tração com nó, resistência ao encastoamento, diâmetro) e estudos in-vivo (resistência tênsil, reação tissular). Os resultados obtidos demonstraram que os fios manchados possuem um desempenho tão bom quanto os sem mancha e podem ser utilizados sem comprometer a qualidade do produto. Isto possibilitou uma redução significativa das perdas totais no processo, de 25% para 17% de todo o material processado / Abstract: Catgut suture is a material composed basically of collagen which is a fibrous protein obtained from the serosa of bovines intestine and is easily absorbed by the human body. Due this characteristic, catgut sutures can be used in several types of surgeries like: endosurgery, ophthalmology, gynecology and urology. Catgut suture is easy to manipulate, however it can produce an intense inflammatory reaction around it. Catgut is considered a very good product in the market of medical devices. In the catgut raw material process there is a great loss of material (approximately 25%). About half of this rejected material is lost because of the presence of speckles. This rejection is, at first time, because of its visual appearance, once the strands with speckles are considered as a damaged suture. The aim of this work is to study the influence of the presence of speckles in the raw material (semi-finished) as well as in the final product, comparing the performance between the strands with and without speckles. In this comparison the tests performed were: visual (appearance); chemicals (chromium an formaldehyde content); physics (knot tensile strength, needle attachment tensile, diameter); "in-vivo" tests (tensile strength, tissue reaction). The results obtained have shown that it is possible to use the suture with speckles because its performance is as good as the ones without speckle and the quality of the product is not affected by their presence. After this study the total losses in the process were significantly reduced from 25% to 17% of all processed material / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química