Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 176-180).

The dark matter search CRESST-II completed its most recent run, Run 32, in 2011. Compared to previous runs, the quantity of data taken in this run increased , significantly. In this work, Oxrop, analysis software in use within the CRESST collaboration, is upgraded to analyse this new data. At the same time, Oxrop's internal structure is improved so that it can now handle data from detectors across different experiments consistently. This upgrade was performed with a view to developing Oxrop's candidacy for use with EURECA, a future dark matter experiment. Oxrop is then used to model CRESST-II data .. First, light detector response to scintillation light produced in y interactions in CRESST -Il' s target crystals is examined. A factor influencing detector efficiency is the time constant of scintillation light production, and this light detector examination is performed with a view to extracting the scintillation time constants of the target crystals. A simple model of light detector response of one exponential rise and two exponential decay times is initially considered. It is shown that this simple model does not closely match the light detector response to y interactions in the crystal scintillator. Empirical extensions to this expected model are then made, allowing for additional decay times. These extensions allow the light detector response to crystal scintillator interactions to be well modelled, and allow estimates of the millikelvin y scintillation time of Ca W04 and Zn W04. This model is then also applied to X-ray interactions directly in the light detectors. It is seen that, even with these model extensions, interactions directly in the light detector still show significant tension with the applied model. This implies that direct calibration of light detectors with X-rays is not possible without a further understanding of light detector response, or that future direct calibrations should be done with optical photons. Position dependent effects in Run 32 calibration data are then studied. A phenomenon that has previously been considered as unrelated to position dependence, the anti-correlation effect between phonon and light detector signals, is shown to exhibit a position dependent effect in at least one lightjphonon detector pair under study. Additionally, the collection efficiency of the light detector is shown to be related to the mean interaction position. Collection efficiency is found to reduce when mean interaction position is close to the cylindrical surfaces of CRESST's Ca W04 target crystals. The magnitude of the difference in light collection: efficiency between surface and bulk interactions is also seen to be correlated with high energy light detector resolution. The WIMP-nucleon cross section limits resulting from the CRESST-II commissioning run (2007) are also reanalysed in this work. The original analysis of the commissioning run accounted only for tungsten recoils in the Ca W04 crystals used in CRESST - II. Here, interactions from calcium and oxygen nuclei are also accounted for. The resulting WIMP-nucleon cross section limits were improved at light WIMP masses -0(10 GeV j c2). These limits show a mild tension with a recent dark matter analysis of Run 32, particularly for WIMP masses below 10 GeV j c2. Possible causes of this tension are discussed

Made available in DSpace on 2014-06-11T19:34:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-10Bitstream added on 2014-06-13T19:44:44Z : No. of bitstreams: 1 catai_re_dr_guara.pdf: 5048506 bytes, checksum: 92a0c290f63def07988a569548fd0d34 (MD5) / Universidade Estadual Paulista (UNESP) / Diante do elevado desenvolvimento tecnológico mundial, o processo de retificação surge cada vez mais como um dos processos de usinagem mais importantes dentro das indústrias. Diante disto, na procura incessante por processos mais capazes e econômicos é que as empresas vêm buscando a otimização da retificação, por exemplo, através da redução da quantidade de fluido de corte a ser utilizada. Desta forma este projeto pretendeu explorar o conceito da utilização racional de fluidos de corte no processo de retificação, e a utilização de defletores aerodinâmicos para minimizar os efeitos das camadas de ar provindas da rotação do rebolo. Foram utilizados dois fluidos de corte (uma solução sintética e um óleo emulsionável), duas ferramentas abrasivas (um rebolo convencional e outro superabrasivo de CBN com ligante vitrificado), um bocal convencional (para o sistema de lubri-refrigeração convencional) e um bocal otimizado de formato arredondado (para o sistema otimizado, que conta ainda com o emprego ou não dos sistemas defletores). Nas condições de aplicação otimizada, fez-se quatro variações da velocidade de saída do fluido, partindo-se de uma relação unitária (velocidade de saída do fluido de corte igual à velocidade de corte do rebolo), tentando verificar se uma velocidade de fluido um pouco menor poderia afetar negativamente às variáveis de saída analisadas (força tangencial de corte, energia específica de retificação, emissão acústica, rugosidade, desgaste diametral, circularidade, tensão residual e microscopia eletrônica de varredura), com o intuito de se buscar a mínima quantidade de fluido de corte possível de ser aplicada sem prejudicar o processo e a qualidade final das peças. Os resultados mostraram a eficiência na utilização dos defletores aerodinâmicos na condição otimizada, os quais para todas... . / Given the high world technological development, the grinding process appears like one of the most important processes inside the industries. Thus, companies are looking for the optmization of the grinding process, for example, through the reduction of the amount of cutting fluid used as the incessant search for more capable and economical processes takes place. Therefore, this project intended to explore the concept of the rational use of cutting fluids in the grinding process, and the utilization of the aerodynamics deflectors to minimize the effects of the air layers created by the grinding wheel rotation. Two cutting fluids (a synthetic cutting fluid and an emulsion oil), two grinding wheels (a conventional and other CBN superabrasive grinding wheel with vitrified bond), a conventional nozzle (for the conventional system of coolant and lubrication) and an optimized nozzle with round format (that was used with and without the deflector system) were used. For conditions of optimized coolant and lubrication, four variations of the coolant jet speed were developed, starting from the unitary relationship (coolant jet speed equal to the wheel peripheral speed), trying to verify whether a minor coolant jet speed could affect negatively the output variables (tangential cutting force, grinding specific energy, acoustic emission, roughness, diametrical wear of grinding wheel, roundness, residual stress and scanning electron microscopy), with the intention of looking for the minimal quantity of cutting fluid that can be applied without harming the process and the final quality of the workpieces. The results showed the efficiency of the aerodynamic deflectors in the optimized coolant/lubrication for all the machining conditions. In relation to the different coolant jet speeds used, it has been noticed that the tendency was to improve the final... (Complete abstract, click electronic address below).

No description available.

Low-head dams are capable of creating dangerous counter-currents just downstream from the structure. These dangerous counter-currents are known as submerged hydraulic jumps and are responsible for hundreds of fatalities at numerous low-head dams across the United States. The counter-current creates high upstream-directed surface velocities across the width of the channel, making it nearly impossible for an individual to escape. This submerged jump can occur during a range of upstream and downstream conditions. Effective, safe and low-cost remediation options must be explored in order to prevent further fatalities at these structures. This document explores such a remediation option: the Multiple Staggered Deflector Design. This remediation option will disrupt uniform upstream-directed surface velocities across the channel within a submerged jump for nearly all downstream conditions that create a submerged jump for a range of upstream conditions. The dam modification is designed such that an individual will escape the submerged jump without severe injury or harm, while being relatively inexpensive and simple to install.

The purpose of this thesis was to perform a comprehensive evaluation of proposed sluiceway deflectors in Hells Canyon Dam with the use of Computational Fluid Dynamics (CFD). A CFD model developed and validated by Politano et al. (2010) was used to assess the downstream performance of the deflectors. Relative performance is measured by effects of the deflectors on the flow field, Total Dissolved Gas (TDG) production, and probability of mechanical fish injury. The deflectors evaluated in this model included the deflector with dimensions determined from a physical model as well as three additional deflector geometries that adjusted elevation, length and transition radius based on the physical model deflector. Physical model testing, at a 1:48 scale, of deflectors on Hells Canyon Dam performed by Haug and Weber (2002) provided a baseline deflector for the deflectors modeled in this study. The physical model was built and tested by the IIHR Hydroscience and Engineering. The performance study that this thesis focuses on was performed at two different tailwater elevations, established with two different total river flowrates of 25 kcfs and 45 kcfs. Each deflector was evaluated considering the spillway jet regime, tailrace flow pattern, and total dissolved gas (TDG) production. According to the model, decreasing the deflector length or increasing the transition radius results in more TDG production at all tailwater elevations. At 45 kcfs, the height of the deflector does not appreciably affect the spillway jet regime or the TDG distribution in the tailrace. However, increasing the deflector elevation at this river flow increases the amount of powerhouse entrainment and induces a recirculation in the western region of the tailrace. The baseline deflector performed best because it had the smallest impact on the tailrace flow pattern and produced the least TDG. The performance of the selected deflector was further evaluated for additional river flow rates of 37 kcfs, 45 kcfs and a 7Q10 flow condition of 71.5 Kcfs, with the 7Q10 condition being tested with and without the deflector. Although the deflector was able to prevent the spillway flow from creating a large amount of downstream TDG the 7Q10 flow condition significantly increased the TDG values downstream of the deflector relative to the other tested conditions. With the chosen deflector TDG values returned to forebay levels after 1 and 3.5 miles for the 37 kcfs and 45 kcfs river flowrates, respectively. With the deflector installed the 7Q10 flow condition creates considerable TDG production however the deflectors are able to reduce TDG production by 10% from the test without a deflector installed. For all evaluated river flows, with the chosen deflector, entrainment from the powerhouse is observed in the simulations; this entrainment is caused by the sluiceway surface jets. As powerhouse flow increases there is an observed decrease in entrainment. This is due to the increase of flow velocity in the streamwise direction, or perpendicular to the direction of entrainment. An important western recirculation that is prominent in the 7Q10 flow condition is also caused by the introduction of deflectors onto the spillways. Reversed flows near the fishtrap region and water directed back into the aerated section of the spillway are consequences of this recirculation. The effect causes a 25% percent increase of entrained flow relative to the no deflector 7Q10 flow. Injury of fish traveling over the spillway and through the sluiceway was estimated with the use of inert spherical particles and the computed flow field. Acceleration and strain experienced by the particles was calculated over the length of the spillway region. Numerical results were compared against literature values published by Deng (2005). Including the deflectors in the design increases the probability that fish will be injured. The most extreme cases of fish injury probability were 37 kcfs and the 7Q10 kcfs flowrates. For these cases, injuries experienced by the fish were 10% and 3% for minor and major injuries respectively. With comparison of the 7Q10 flows it appears that the inclusion of the deflector increases the induced minor injury induce from 5% to 10% and the major injury from 1% to 3%. Fish tailrace residence time was calculated using inert particles introduced to the computed fluid flow field. These particles were tracked for 650 feet past the sluiceway inlets and their time to completion was recorded. Particles were released from the sluiceways as well as the powerhouses for the 37 kcfs, 45kcfs and 7Q10 flow conditions. Particles released from the sluiceways reduced in residence time with an increase in sluiceway flowrate. With some amount of powerhouse entrainment increasing the residence time of the particles released from the powerhouse. These particles follow the entrainment to the deep low velocity region in the stilling basin. As the lateral flow increases some of the particles released from the spillway will join the high speed jets produced by the deflectors and their residence time will be reduced. According to the model, deflectors consistently reduce overall residence time and are therefore not expected to increase fish migration time. Water surface elevation near the fishtrap was measured for the 25 kcfs, 37 kcfs, 45 kcfs and 7Q10 flow conditions. The wave height near the fishtrap for the 7Q10 deflector case was predicted to be about one foot above the estimated water surface elevation. According to the model the inclusion of the deflector reduces the wave height.

Thesis (M.E.E.)--University of Delaware, 2006. / Principal faculty advisor: Fouad Kiamilev, Dept. of Electrical and Computer Engineering. Includes bibliographical references.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 85-89). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 85-89). Also available on the Internet.

Resumo: Diante do elevado desenvolvimento tecnológico mundial, o processo de retificação surge cada vez mais como um dos processos de usinagem mais importantes dentro das indústrias. Diante disto, na procura incessante por processos mais capazes e econômicos é que as empresas vêm buscando a otimização da retificação, por exemplo, através da redução da quantidade de fluido de corte a ser utilizada. Desta forma este projeto pretendeu explorar o conceito da utilização racional de fluidos de corte no processo de retificação, e a utilização de defletores aerodinâmicos para minimizar os efeitos das camadas de ar provindas da rotação do rebolo. Foram utilizados dois fluidos de corte (uma solução sintética e um óleo emulsionável), duas ferramentas abrasivas (um rebolo convencional e outro superabrasivo de CBN com ligante vitrificado), um bocal convencional (para o sistema de lubri-refrigeração convencional) e um bocal otimizado de formato arredondado (para o sistema otimizado, que conta ainda com o emprego ou não dos sistemas defletores). Nas condições de aplicação otimizada, fez-se quatro variações da velocidade de saída do fluido, partindo-se de uma relação unitária (velocidade de saída do fluido de corte igual à velocidade de corte do rebolo), tentando verificar se uma velocidade de fluido um pouco menor poderia afetar negativamente às variáveis de saída analisadas (força tangencial de corte, energia específica de retificação, emissão acústica, rugosidade, desgaste diametral, circularidade, tensão residual e microscopia eletrônica de varredura), com o intuito de se buscar a mínima quantidade de fluido de corte possível de ser aplicada sem prejudicar o processo e a qualidade final das peças. Os resultados mostraram a eficiência na utilização dos defletores aerodinâmicos na condição otimizada, os quais para todas... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: Given the high world technological development, the grinding process appears like one of the most important processes inside the industries. Thus, companies are looking for the optmization of the grinding process, for example, through the reduction of the amount of cutting fluid used as the incessant search for more capable and economical processes takes place. Therefore, this project intended to explore the concept of the rational use of cutting fluids in the grinding process, and the utilization of the aerodynamics deflectors to minimize the effects of the air layers created by the grinding wheel rotation. Two cutting fluids (a synthetic cutting fluid and an emulsion oil), two grinding wheels (a conventional and other CBN superabrasive grinding wheel with vitrified bond), a conventional nozzle (for the conventional system of coolant and lubrication) and an optimized nozzle with round format (that was used with and without the deflector system) were used. For conditions of optimized coolant and lubrication, four variations of the coolant jet speed were developed, starting from the unitary relationship (coolant jet speed equal to the wheel peripheral speed), trying to verify whether a minor coolant jet speed could affect negatively the output variables (tangential cutting force, grinding specific energy, acoustic emission, roughness, diametrical wear of grinding wheel, roundness, residual stress and scanning electron microscopy), with the intention of looking for the minimal quantity of cutting fluid that can be applied without harming the process and the final quality of the workpieces. The results showed the efficiency of the aerodynamic deflectors in the optimized coolant/lubrication for all the machining conditions. In relation to the different coolant jet speeds used, it has been noticed that the tendency was to improve the final... (Complete abstract, click electronic address below). / Orientador: Eduardo Carlos Bianchi / Coorientador: Marcos Valério Ribeiro / Banca: Paulo Roberto de Aguiar / Banca: Marcos Tadeu Tibúrcio Gonçalves / Banca: Leonardo Roberto da Silva / Banca: Anselmo Eduardo Diniz / Doutor