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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.
21

Utilidad de la ecografía de alta resolución en la valoración de la aterosclerosis preclínica, riesgo cardiovascular y diagnóstico de la hipercolesterolemia familiar

Junyent Priu, Mireia 21 November 2006 (has links)
La presente tesis valora la utilidad de la ecografía carotídea de alta resolución, como técnica diagnóstica incruenta, útil, validada, reproducible y de bajo coste que nos permite:1. La detección de la aterosclerosis preclínica incipiente mediante la determinación del grosor íntima-media (GIM) carotídeo.2. La detección de la aterosclerosis avanzada mediante la presencia de placas de ateroma.3. La estratificación del riesgo cardiovascular más allá de los factores de riesgo tradicionales evaluados mediante la ecuación de riesgo de Framingham.4. La evaluación de la carga aterosclerótica de cada sujeto en función del impacto de los diferentes factores de riesgo en la pared arterial.5. Adaptar la intensidad de la intervención sobre los factores de riesgo en función de los hallazgos ecográficos.Asimismo, la ecografía de los tendones de Aquiles nos permite confirmar la probabilidad diagnóstica de la Hipercolesterolemia Familiar mediante la detección de unos tendones engrosados o con una ecoestructura alterada (xantomas tendinosos).
22

The boundary of the subducting slab and mantle wedge of an incipient arc: P-T-D history, mixing, and fluid-related processes recorded in the Dalrymple Amphibolite, Palawan Ophiolite (the Philippines) / 初期島弧の沈み込むスラブーマントルウェッジ境界:フィリピン・パラワンオフィオライト中のダーリンプル角閃岩に記録された温度・圧力・変形履歴、岩石混合および流体の関与プロセスについて

VALERA, Gabriel Theophilus Vinalay 23 March 2022 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第23713号 / 理博第4803号 / 新制||理||1687(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 河上 哲生, 教授 田上 高広, 教授 下林 典正 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
23

Diagnostico de carie : metodo clinico e de fluorescencia laser

Pinelli, Camila 06 August 2001 (has links)
Orientadores: Monica Campos Serra, Leonor de Castro Monteiro Loffredo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-07-28T08:37:40Z (GMT). No. of bitstreams: 1 Pinelli_Camila_D.pdf: 3436834 bytes, checksum: 2866910ab5e9e39232f71400818f21be (MD5) Previous issue date: 2001 / Resumo: O diagnóstico de cárie tem assumido uma importância particular, desde que a habilidade em se detectar lesões reversíveis oferece diversas vantagens para o paciente, em termos de tratamento e cuidados preventivos. A inspeção visual das superfícies é um dos métodos diagnósticos mais utilizados e os critérios: cor, brilho, textura e distância das lesões em relação à margem gengival precisam ser considerados para a determinação da atividade de cárie no esmalte não-cavitado. Um aparelho laser fluorescente, KaVo DIAGNOdent@, foi proposto para quantificar a perda mineral de lesões de cárie e, a validade e reprodutibilidade de seus resultados têm sido investigadas in vitro. Devido a dificuldade em se determinar clinicamente a atividade ou inatividade de lesões de cárie incipientes e, frente à possibilidade de utilização do laser fluorescente como um auxiliar diagnóstico na quantificação da perda mineral, o recente trabalho teve como objetivos: 1. promover a difusão de conhecimentos e de critérios clínicos para o diagnóstico de lesões de cárie ativas e paralisadas; 2. determinar, in vivo, a reprodutibilidade de duas escalas de classificação dos resultados do laser DIAGNOdent@, propondo uma escala para o diagnóstico de cárie em superficies lisas livres; 3. pesquisar a reprodutibilidade e a validade do laser DIAGNOdent@, em lesões de cárie de superflcies lisas livres, quando comparado com o critério clínico de validação, in vivo. Dentro das condições experimentais deste trabalho, observou-se que: 1. através da divulgação de casos clínicos, os critérios de atividade e inatividade das lesões de cárie foram ilustrados, incentivando o diagnóstico diferencial e precoce; 2. a escala de classificação dos valores do laser DIAGNOdent@ que mostrou melhor desempenho no diagnóstico de cárie, em superfícies lisas livres, foi a escala de LUSSI et al., 1999 adaptada por PINELLI et al., 2001 (unpublished data), sendo proposta para o diagnóstico de lesões incipientes em superfícies lisas livres; 3. o laser DIAGNOdent@ mostrou-se reprodutível e válido no diagnóstico de cárie in vivo, e a associação dos métodos clínico e laser pode aprimorar a eficácia do diagnóstico / Abstract: Caries diagnosis has assumed a particular importance, since the ability to detect earlier the reversible lesions offers several advantages for the patients, in terms of treatment and preventive measures. The visual inspection of the surfaces remains the method of first choice and clinical criteria such as color, shininess, roughness, and distance from the lesion to the gingival margin must be considered when determining caries activity on non-cavitated enamel. A laser fluorescent system, Ka V o DIAGNOdent@, was proposed to quantify mineral loss of caries lesions, and the validity and the reproducibility of the laser results has been investigated in vitro. Due to difficulty at determining clinical caries activity or inactivity, and due to possibilities of applying the laser fluorescence device as an auxiliary method to quantify mineral loss, the present work was aimed to: 1. disclose some clinical criteria for detecting active or arrested caries lesions; 2. verify, in vivo, the reproducibility of two scales of classification for DIAGNOdent@, and to propose a scale for the diagnosis of caries on free smooth surfaces; 3. test the reproducibility and validity of DIAGNOdent@, on caries lesions of free smooth surfaces, when the validation criterion was the visual examination, in vivo. Under the experimental conditions, it was verified: 1. afier the publication of clinical cases, the clinical criteria related to caries activity or inactivity were illustrated, aiming at differential and earlier diagnoses; 2. the scale which showed a better performance in caries diagnosis of free smooth surfaces was the scale proposed by LUSSI et al., 1999, modified by PINELLI et al., 2001 (unpublished data), and _it was suggested to diagnose incipient caries on free smooth surfaces; 3. the laser DIAGNOdent@ was reproducible and valid for caries diagnosis in vivo, and the utilization of both methods can improve caries diagnostic efficacy / Doutorado / Dentística / Doutor em Clínica Odontológica
24

Effects of Diluent Addition and Metal Support Interactions in Heterogeneous Catalysis: SiC/VPO Catalysts for Maleic Anhydride Production and Co/Silica Supported Catalysts for FTS

Kababji, Ala'a Hamed 23 March 2009 (has links)
This work begins with an introduction to catalysis focusing on heterogeneous systems and surface science phenomena. A study on the partial oxidation reaction of n-butane to maleic anhydride (MA) is presented in the first part. MA supplies are barely adequate for market requirements due to continued strong demand. Only slight improvement in catalytic performance would be welcome in the industrial community. The vanadium phosphorus oxide (VPO) catalyst was used in this work. The reaction is highly exothermic and the need to properly support the catalyst, not only for good dispersion but adequate heat dissipation is of crucial importance. For this, alpha-SiC commercial powders were used in synthesizing the catalyst due to its high thermal conductivity. Up to 25% MA yields were obtained and the reaction temperature was lowered by up to 28% using SiC/VPO mixed catalysts. The second part of this work is focused on the Fischer-Tropsch synthesis (FTS) process using cobalt silica supported catalysts. The main objective is the production of synthetic ultra high purity jet fuel (JP5). This is a very timely topic given the energy issues our world is facing. Almost all aspects of the FTS process have been extensively studied, however the effects of calcination temperature and silica support structure on the catalyst performance are lacking in literature. The catalysts were prepared using various silica supports. The catalysts had different drying and calcination temperatures. It was found that lower support surface area and calcination temperature catalysts exhibited higher activity due to lower support cobalt phase interaction. Co/silica catalysts calcined at 573K showed the highest CO conversion and the lowest CH4 selectivity. Catalysts prepared with 300m²/g support surface area exhibited 79.5% C5+ selectivity due to higher reducibility and less metal support interaction. The properties and performance of various prepared catalysts in both VPO and Co/silica systems are characterized by FTIR, XRD, BET, GC and XPS techniques. Theoretical FTS deactivation by sintering calculations and SiC/VPO particle temperature gradient calculations are presented as well. Finally, conclusions and future work on improving the yield and selectivity and scaling up the bench top setups are also presented.
25

Development of Iron-based Catalyst for Isobutane Dehydrogenation to Isobutylene

Alahmadi, Faisal 07 1900 (has links)
Abstract: Isobutylene is a high demand chemical that contributes to the production of fuel, plastic, and rubbers. It is produced industrially by different processes, as a byproduct of steam cracking of naphtha or a fluidized catalytic cracking or by isobutane dehydrogenation. Catalytic dehydrogenation of isobutane is in increasing importance because of the growing demand for isobutylene and the better economic advantage compared to other isobutylene production processes. Isobutane dehydrogenation is an endothermic reaction and to achieve good yields; it is preferred to work at higher temperatures. At these temperatures, carbon deposition leads to catalyst deactivation, which requires the catalyst to be regenerated on a frequent basis. Most of the current processes to produce isobutylene use either expensive platinum-based metal or toxic chromium-based catalysis. Hence, there is a demand to search for alternative catalysts that are a relatively cheap and non-toxic. To achieve this goal, Zirconia-supported Iron catalysts were prepared. To study the effect of active phase distribution, different iron loadings were tested for impregnation (3% to 10%) and co-precipitation (10%-20%). The catalysts show promising results that can achieve an isobutylene selectivity and yield of 91% and 31%, respectively, with isobutane conversion of 35%.
26

Features of the Femoral Proximocaudal Joint Capsule Insertion Among Canids

Lawler, Dennis, Tangredi, Basil, Owens, Jerry, Evans, Richard, Widga, Christopher, Martin, Terrance, Smith, Gail, Schulz, Kurt, Kohn, Luci 01 December 2019 (has links)
This observational study was conducted to evaluate the anatomic relationship between the proximocaudal femoral joint capsule insertion and the femoral caudolateral curvilinear osteophyte (CCO), across ancient and modern domestic and non-domestic canids. Museum specimens of proximal femora were screened for presence of remnant enthesophytes of the caudal joint capsule insertion (first inclusion criterion) and then for the CCO (second inclusion criterion). The initially screened population included 267 dry bone specimens: Six Canis species, hybrid coyote × domestic dog, and five vulpines (three Vulpes species, one Urocyon, and one Nyctereutes). Proximocaudal joint capsule insertion remnant enthesophytes were limiting at n = 19 specimens: Seven ancient domestic dogs, four modern coyotes, two ancient coyotes, two modern hybrid coyote × dog, two modern red foxes, and two modern raccoon dogs. The joint capsule enthesophytes are associated with inflammation, but are observed far less frequently than the CCO. The CCO is seen radiographically but is visible more frequently by direct inspection. The primary inclusion criterion necessarily was a visible caudal joint capsule insertion; spatial relationships of the CCO can be assigned with confidence only when a capsule insertion line can be recognized clearly. We demonstrate that the anatomic CCO associates with the joint capsule insertion being nonspecific and species-independent. A joint capsule insertion-CCO spatial relationship across species is an important new observation, strongly indicating that both are pathological features. Our data indicate need for new research to characterize the canid coxofemoral joint and its overt and incipient pathology in a phylogenetic context. Anat Rec, 302:2164–2170, 2019.
27

High Impedance Arc Fault Detection in a Manhole Environment.

Cooke, Thomas Arthur 18 December 2010 (has links) (PDF)
The scope of this thesis was to develop a prototype high-impedance arc detection system that a utility worker could use as an early warning system while working in a manhole environment. As part of this system sensors and algorithms were developed to increase the sensitivity of detecting an arc while ignoring loads that can give false positive signatures for arcing. The latest technology was used to repeat measurements performed in previous research from decades ago that lacked in sampling speed and amplitude resolution. Several types of arcs were produced and analyzed so to establish a library of various waveform and frequency signatures. The system was constructed as a development unit and is currently gathering information in the field. Data being collected will be analyzed so future revisions will give higher confidence levels of arc detection. Other future plans involve designing a more compact and portable unit.
28

Effect of Seepage on Incipient Motion and Rheology of Cohesionless Soil / 非粘着性土の初期移動過程に対する浸透の影響とレオロジー特性

Jewel, Md. Arif Hossain 24 September 2021 (has links)
京都大学 / 新制・課程博士 / 博士(農学) / 甲第23528号 / 農博第2475号 / 新制||農||1087(附属図書館) / 学位論文||R3||N5359(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 藤原 正幸, 教授 中村 公人, 准教授 藤澤 和謙 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM
29

Experimental Investigation of the Role of Turbulence Fluctuations on Incipient Motion of Sediment

Celik, Ahmet Ozan 08 September 2011 (has links)
The movement of granular material along a streambed has been a challenging subject for researchers for more than a century. Predicting the limiting case of nearly zero bedload transport, usually referred to as threshold of motion or critical condition, is even more challenging due to the highly fluctuating nature of turbulent flow. Numerous works have advocated that the peak turbulent forces, randomly occurring in time and space with magnitudes higher than the average, initiate the bed material motion. More recent findings have shown that not only the magnitude of the peak turbulent forces acting on individual grains but their duration as well have to be considered for determining the incipient conditions. Their product, or impulse, is better suited for specifying such conditions. The goal of this study was to investigate the mechanism responsible for initiation of sediment motion under turbulent flow conditions. The impulse concept was investigated by utilizing appropriate measurement methods in the laboratory for determining the condition of incipient motion. The experimental program included measurements of particle entrainment rates of a mobile grain and turbulence induced forces acting upon a fixed grain for a range of flow conditions. In addition, near bed flow velocities were measured synchronously with both the entrainment and pressure measurements at turbulent resolving frequencies. Results of this work covered the limitations and uncertainties associated with the experimental methods employed, and the description of the inadequacies of existing incipient motion models via the impulse framework. The extreme sensitivity of bed material activity to minute adjustments in flow conditions was explained by the associated change in the frequency of impulse events. The probability density function proposed for impulse was used together with the critical impulse to estimate the particle entrainment rate for a range of flow conditions. It was shown that the impulse events with potential to dislodge the grain were occurring mostly during sweep type of flow structures. The impulse events were also typically accompanied by positive lift forces. The force patterns showed that the positive peaks in the lift consistently occurred before and after the impulse events in the drag force. The magnitude of these lift forces were significantly higher in the wake of a cylinder compared to that of uniform flow conditions. The time average lift force in the wake of a cylinder was also observed to be positive with magnitudes reaching more than 30% of the submerged weight of the particle. The cylinder caused the downstream turbulence intensity to increase slightly but the particle entrainment rate to increase significantly. This finding provided a physically based explanation for the modification of turbulent force fluctuations and resulting changes in the particle movement rates by such unsteady flow conditions. / Ph. D.
30

Hydraulic Characterization of Mounded Gravel Fish Nests: Incipient Motion Criteria and Despiking Acoustic Doppler Velocimeter Data

Kraus, Samuel Aloysius 06 June 2024 (has links)
The bluehead chub (Nocomis leptocephalus) is a keystone species, an ecosystem engi- neer that constructs mounded gravel nests for spawning. Chubs provide benefits for other spawning fishes, predators, and benthic organisms through their nest construction. This study seeks to apply sediment transport models to find incipient motion criteria and erosion susceptibility of chubs nests. Field water flow velocities were measured with an acoustic Doppler velocimeter (ADV) in Tom's Creek, Blacksburg, Virginia, USA. ADVs are often used to collect in-situ turbulent velocity data. In almost all applications of ADVs, erroneous spikes are recorded during collection, which can significantly distort turbulence statistics de- rived from velocity fluctuations. In this study, a bivariate kernel density estimation despiking algorithm is compared to a novel univariate simplification developed as part of this work. Despiking methods are evaluated using field ADV and direct numerical simulation (DNS) data of a turbulent boundary layer. Visual assessment of despiked velocity time series and power spectra and corresponding changes in statistical moments, as well as response to arti- ficial spiking of DNS data, yield valid performance of the univariate method. After despiking chub nest data, multiple methods of finding bed shear stress from velocity vertical profiles are evaluated. Bed shear stress is found over the profile of 26 field nests. The ambient to peak flow stress amplification due to a nest's bed protrusion is found to be a proportion of τ = 1.66τ to determine a critical ambient Shields parameter of approximately τ∗ = 0.03 pa c,a for nests. / Master of Science / The bluehead chub is a keystone species, an ecosystem engineer that constructs mounded gravel nests for spawning. These nests benefit numerous other species within their habitat. The possibility of nest erosion is characterized in this study using existing sediment transport principles. Nest flow characteristics are measured using an acoustic Doppler velocimeter (ADV). ADVs are often the instrument of choice in measuring water velocity. The high resolution of these devices can capture turbulent flows well, however data collection often results in inclusion of erroneous spikes in velocity. These spikes represent points deemed impossible due to their sudden change in velocity magnitude. Spikes do not have a large effect on average velocities of ADV data, but can influence turbulence statistics that describe the turbulent fluctuations in flow velocities. To remove spikes, multiple methods incorporate different outlier detection principles. This study evaluates a popular method that employs a two-dimensional kernel density estimation (KDE) algorithm. A recent study suggested the possible simplification of this method to use a one-dimensional kernel density estimation instead. Both the 1D and 2D methods are evaluated in this study in how they filter ADV data and whether it results in a clean, improved velocity time series that would be expected in turbulent flows. A novel 1D KDE method was also developed as part of this study. The new method is found to produce the most reliable filtering. Despiked ADV data is used to characterize the hydraulics over bluehead chub nests sampled in Tom's Creek, Blacksburg, Virginia, USA. Hydraulics are evaluated to see if ambient flow upstream of a nest can characterize the flow characteristics over the peak of the nest. Shear stress amplification over the nest is used to find a critical threshold for nest erosion based on ambient flows. Stress amplification in the ambient flow to the peak over the nest is found to be a simple proportion, and amplification factor of 1.66. This means we expect shear stress over the peak of a chub nest to be 1.66 times greater than the ambient bed shear stress upstream of the nest. This amplification factor can be used with existing methods to calculate critical non- dimensional shear stress values, also known as the critical Shields stress. After accounting for the amplification factor of 1.66, a critical Shields of approximately 0.03 is found.

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