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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.
51

Application and Evaluation of Extended Release Technology to Loop Diuretics

Hamed, Ehab Ahmed Mamdouh January 2002 (has links)
No description available.
52

ELECTROCHEMICAL/ELECTROFLOTATION PROCESS FOR DYE WASTEWATER TREATMENT

Butler, Erick 08 August 2013 (has links)
No description available.
53

Rapid Prediction of Tsunamis and Storm Surges Using Machine Learning

Lee, Michael 27 April 2021 (has links)
Tsunami and storm surge are two of the main destructive and costly natural hazards faced by coastal communities around the world. To enhance coastal resilience and to develop effective risk management strategies, accurate and efficient tsunami and storm surge prediction models are needed. However, existing physics-based numerical models have the disadvantage of being difficult to satisfy both accuracy and efficiency at the same time. In this dissertation, several surrogate models are developed using statistical and machine learning techniques that can rapidly predict a tsunami and storm surge without substantial loss of accuracy, with respect to high-fidelity physics-based models. First, a tsunami run-up response function (TRRF) model is developed that can rapidly predict a tsunami run-up distribution from earthquake fault parameters. This new surrogate modeling approach reduces the number of simulations required to build a surrogate model by separately modeling the leading order contribution and the residual part of the tsunami run-up distribution. Secondly, a TRRF-based inversion (TRRF-INV) model is developed that can infer a tsunami source and its impact from tsunami run-up records. Since this new tsunami inversion model is based on the TRRF model, it can perform a large number of tsunami forward simulations in tsunami inversion modeling, which is impossible with physics-based models. And lastly, a one-dimensional convolutional neural network combined with principal component analysis and k-means clustering (C1PKNet) model is developed that can rapidly predict the peak storm surge from tropical cyclone track time series. Because the C1PKNet model uses the tropical cyclone track time series, it has the advantage of being able to predict more diverse tropical cyclone scenarios than the existing surrogate models that rely on a tropical cyclone condition at one moment (usually at or near landfall). The surrogate models developed in this dissertation have the potential to save lives, mitigate coastal hazard damage, and promote resilient coastal communities. / Doctor of Philosophy / Tsunami and storm surge can cause extensive damage to coastal communities; to reduce this damage, accurate and fast computer models are needed that can predict the water level change caused by these coastal hazards. The problem is that existing physics-based computer models are either accurate but slow or less accurate but fast. In this dissertation, three new computer models are developed using statistical and machine learning techniques that can rapidly predict a tsunami and storm surge without substantial loss of accuracy compared to the accurate physics-based computer models. Three computer models are as follows: (1) A computer model that can rapidly predict the maximum ground elevation wetted by the tsunami along the coastline from earthquake information, (2) A computer model that can reversely predict a tsunami source and its impact from the observations of the maximum ground elevation wetted by the tsunami, (3) A computer model that can rapidly predict peak storm surges across a wide range of coastal areas from the tropical cyclone's track position over time. These new computer models have the potential to improve forecasting capabilities, advance understanding of historical tsunami and storm surge events, and lead to better preparedness plans for possible future tsunamis and storm surges.
54

Response Surface Design and Analysis in the Presence of Restricted Randomization

Parker, Peter A. 31 March 2005 (has links)
Practical restrictions on randomization are commonplace in industrial experiments due to the presence of hard-to-change or costly-to-change factors. Employing a split-plot design structure minimizes the number of required experimental settings for the hard-to-change factors. In this research, we propose classes of equivalent estimation second-order response surface split-plot designs for which the ordinary least squares estimates of the model are equivalent to the generalized least squares estimates. Designs that possess the equivalence property enjoy the advantages of best linear unbiased estimates and design selection that is robust to model misspecification and independent of the variance components. We present a generalized proof of the equivalence conditions that enables the development of several systematic design construction strategies and provides the ability to verify numerically that a design provides equivalent estimates, resulting in a broad catalog of designs. We explore the construction of balanced and unbalanced split-plot versions of the central composite and Box-Behnken designs. In addition, we illustrate the utility of numerical verification in generating D-optimal and minimal point designs, including split-plot versions of the Notz, Hoke, Box and Draper, and hybrid designs. Finally, we consider the practical implications of analyzing a near-equivalent design when a suitable equivalent design is not available. By simulation, we compare methods of estimation to provide a practitioner with guidance on analysis alternatives when a best linear unbiased estimator is not available. Our goal throughout this research is to develop practical experimentation strategies for restricted randomization that are consistent with the philosophy of traditional response surface methodology. / Ph. D.
55

Characterization and modeling of dry etch processes for titanium nitride and titanium films in Cl₂/N₂ and BCl₃ plasmas

Muthukrishnan, N. Moorthy 06 June 2008 (has links)
In the past few years, the demands for high speed semiconductor integrated circuits have warranted new techniques in their fabrication process which will meet the ever-shrinking dimensions. The gaseous plasma assisted etching is one of these revolutionary processes. However, the plasma and the etch process are very complex in nature. It has been very difficult to understand various species present in the plasma and their role in the etch reaction. In addition, the submicron geometries also require interconnect materials which will satisfy the necessary properties such as thermal stability and low electrical resistance. Titanium (Ti) and titanium nitride (TiN) are widely used as barriers between aluminum (Al) and silicon (Si) to prevent the destructive intermixing of these two materials. The process of patterning of the interconnect containing Ti and TiN along with Al has been a challenge to the semiconductor process engineers. Therefore, complete characterization of the plasma etch process of Ti and TiN films and development of mathematical models to represent the responses such as the etch rate and uniformity is necessary for a good understanding of the etching process. A robust and well controlled metal etch process usually results in good die yield per wafer and hence can translate into higher profits for the semiconductor manufacturer. The objective of this dissertation is to characterize the plasma etch processes of Ti and TiN films in chlorine containing plasmas such as BCl₃ and Cl₂/N₂ and to develop mathematical models for the etch processes using statistical experimental design and analysis technique known as Response Surface Methodology (RSM). In this work, classical experiments are conducted on the plasma etch process of Ti and TiN films by varying the process parameters, such as gas flow, radio frequency (RF) power, reaction pressure, and temperature, one parameter at a time, while maintaining the other parameters constant. The variation in the etch rate with the change in the process parameter of the film is studied and the results were explained in terms of the concepts of plasma. These experiments, while providing very good understanding of the main effects of the parameters, yield little or no information on the higher order effects or interaction between the process parameters. Therefore, modern experimental design and analysis techniques using computerized statistical methods need to be employed for developing mathematical models for these complex plasma etch processes. The second part of this dissertation concentrates on the Design and Analysis of Experiments using Response Surface Methodology (RSM) and development of models for the etch rate and the etch uniformity of the Ti and TiN films in chlorine-containing plasmas such as Cl₂/N₂ and Cl₂/N₂/BCl₃. A complete characterization of the plasma etch process of Ti and TiN films is achieved with the RSM technique and a well fitting and statistically significant models have been developed for the process responses, such as the etch rate and the etch uniformity. These models also provide a means for quantitative comparison of main effects, which are also known as first order effects, second order effects and two factor interactions. The models, thus developed, can be effectively used for an etch process optimization, prediction of the responses without actually conducting the experiments, and the determination of process window. This dissertation work has achieved a finite study of the plasma etch process of Ti and TiN films. There is tremendous potential and scope for further research in this area, limited only by the available resources for wafer processing. A few of the possibilities for further research is discussed in the next few sentences. The optimized process derived from the RSM technique needs to be implemented in the actual production process of the semiconductor ICs and its effects on the wafer topography, etch residue and the resulting die yield have to be studied. More research studies are needed to examine the effect of process parameters such as temperature, the size and shape of the etch chamber, the quality of the film being etched, among other parameters. It is worth emphasizing in this respect that this dissertation marks beginning of research work into the ever-increasing complexities of gas plasma. / Ph. D.
56

Performance study of photocatalytic oxidation for the abatement of volatile organic compounds from indoor air environments / Étude de l’efficacité de l’élimination par photocatalyse des composés organiques volatils présents dans l’air intérieur

Vildozo, Daniel 02 July 2010 (has links)
Ces derniers temps, des procédés commerciaux basés sur la technologie photocatalytique, sont arrivés sur le marché, afin de satisfaire la demande croissante du traitement de l’air intérieur. L’objectif de ce présent travail est de développer une nouvelle méthodologie pour évaluer l’efficacité de ce nouveau procédé. Pour l’étude de l’application de la photocatalyse au traitement de l’air intérieur, un dispositif expérimental a été mis au point et deux méthodes analytiques ont été développées (ATD-GCMS et GC-PDHID). La performance de la dégradation photocatalytique du 2-propanol et du toluène à faibles concentrations (ppbv) a été étudiée. L’influence des différents paramètres (humidité relative, débit, concentration initiale, etc.) et leurs interactions sur la conversion, la formation des intermédiaires et la minéralisation au CO2 a été établie / Many commercial systems based in the photocatalytic technology have reached the market recently in order to address the growing demand for improve poor indoor air qualities. The present work deals with the development of a new methodology in order to evaluate the efficiency of this process. For the study of photocatalytic oxidation for indoor air applications, an experimental set-up was designed and two analytical tools (ATD-GC-MS and GC-PDHID) were developed. The performance of the photocatalytic treatment of 2-propanol and toluene at indoor air concentrations levels (ppbv) were realised. The influence of several parameters and their interactions effects on the conversion, by-product formation and mineralization to CO2 were established
57

Residual stresses in Ti-6Al-4V from low energy laser repair welding / Restspänningar i Ti-6Al-4V av lågenergetisk laserreparationssvetsning

Ericson, Peter January 2018 (has links)
Millimeterstora och svårupptäckta defekter kan uppstå internt i stora och komplexa gjutgods av Ti-6Al-4V, ibland går dessa oupptäckta tills detaljen genomgått mekanisk bearbetning och en stor kostnad redan har gått in i den. Dessa defekter och andra industriella olyckshändelser leder till ett behov av additiva reparationsmetoder där den för tillfället rådande metoden är TIG-svetsning. Denna metod reparerar defekterna men leder till oacceptabla restspänningar vilka kan åtgärdas med värmebehandling som i sin tur kan orsaka ytdefekten alpha case. Därav finns ett industriellt behov av reparationsmetoder som leder till mindre eller negligerbara restspänningsnivåer i reparerad detalj. Detta arbete utfört hos GKN Aerospace – Engine Products Sweden i Trollhättan analyserar eventuella förhållanden mellan parametrarna Effekt, Spot size, och Svetshastighet och de resulterande restspänningarna i ett lågparameterområde på materialet Ti-6Al-4V. En parameterrymd uppspänd av 17 parameteruppsättningar etablerades, svetsades och analyserades med mikrografi. Ur denna rymd simulerades de 8 yttre parametrarna med hjälpa av Finita Elementmetoden i svetssimuleringsmjukvaran MARC och ett förhållande mellan ingående parametrar och resulterande restspänningar undersöktes. En statistiskt säkerställd trend erhölls för att en minskad Svetshastighet leder till minskade tvärspänningar i mitten på en 20mm lång svetssträng. Detta är applicerbart för svetsar nyttjande start och stopplåtar. Det noterades även att en ökning i Effekt eller Spot size, eller en minskning utav svetshastigheten leder till att det av restspänningar utsatta området ökar i storlek. Detta är har implikationer för efterföljande värmebehandling i avgörandet av form och storlek på området som skall värmebehandlas. / Minute defects may occur in large complex Ti-6Al-4V castings, sometimes these are unnoticed until after machining and a high cost has been sunk into the part. These defect and other potential manufacturing mishaps render a need for additive repair methods. The state of the art method TIG welding can repair the parts but may leave unacceptable residual stresses, where the state of the art solution of Post Weld Heat Treatment might create a surface defect known as alpha case. Therefore there is a need for a repair weld method that results in lesser or negligible residual stresses. This thesis, carried out at GKN Aerospace – Engine Products Sweden, Trollhättan analyses the potential relationships between the laser welding parameters Power, Spot size, and Weld speed and the resulting residual stresses in a low energy parameter area on the material Ti-6Al-4V. A parameter box of 17 parameter sets was established, laid down and analyzed under micrograph, of this box the outer 8 parameter sets were simulated via the Finite Element Analysis welding simulation software MARC and a relationship between the input parameters and their resulting residual stresses was analyzed. A statistically significant trend was found supporting the claim that a decrease in transversal stresses in the center of a 20mm weld line is caused by an increase in Weld speed. This has implications for welds using run-on & run-of plates. It was also noted that an increase in Power or Spot size, or a decrease in Weld speed increases the area under residual stress; both as individual parameters and in synergy. This has implications for Post Weld Heat Treatment in determining the size and shape of the area in need of treatment.
58

Vývoj a optimalizace SPE metody pro prekoncentraci a stanovení fluorotelomerních alkoholů ve vodách / Development and optimization of SPE method for preconcentration and determination of fluorotelomeric alcohols in water

Ševčík, Václav January 2012 (has links)
New GC-MS method combined with SPE preconcentration step has been developed and optimized for the determination of selected fluorotelomer alcohols in aqueous samples by advanced statistical method in this thesis. 1H,1H,2H,2H-perfluoro-1-octanol (6:2 FTOH) and 1H,1H,2H,2H-perfluoro-1-decanol (8:2 FTOH) have been selected as the analytes. The influence of several factors, such as the sample volume, the carrier gas pressure, the sampling time and the injector temperature on the system response have been studied during the optimization. Utilizing the statistical software Minitab 16 and series of experiments, the optimal values of relevant factors and a suitable type of ionization were found for both analytes. Limits of detection of GC-MS method are 0.24 ng/mL for 6:2 FTOH and 0.42 ng/mL for 8:2 FTOH. Several factors, such as the type and the volume of conditioning agent, the speed of conditioning, the speed of sample flow, the method of column drying, the type and the volume of eluent have been tested for SPE. The optima of these factors were determined using Minitab 16 software. The extraction efficiency dependence on the concentration and volume of the stock solution was used to set the limitation of SPE for the determination of fluorotelomer alcohols. The maximum volume of sample equals to 400 mL...
59

Utilização da metodologia de superfície de resposta no desenvolvimento de um molho tipo Pesto visando a atividade antioxidante / Utilization of response surface methodology in the development of a Pesto sauce to maximize its antioxidant activity

Afonso, Guilherme 06 September 2006 (has links)
Evidências recentes têm demonstrado que dietas com elevado conteúdo de vegetais, frutas e grãos podem reduzir o risco de diversas doenças não transmissíveis. As propriedades benéficas desses alimentos têm sido atribuídas, em grande parte, à presença de substâncias antioxidantes, que são capazes de diminuir os efeitos prejudiciais dos radicais livres. O objetivo deste trabalho foi desenvolver uma formulação de molho tipo Pesto, com base nas propriedades antioxidantes dos seus ingredientes principais: manjericão, castanha do Brasil e azeite de oliva extra virgem. A metodologia foi divida em duas fases: a primeira consistiu na avaliação da interação entre os componentes com atividade antioxidante (AA) presentes nos ingredientes principais do molho, realizada através da metodologia de superfície de resposta por modelagem de misturas. Foi utilizado um planejamento centróide simplex, no qual a resposta medida foi a atividade antioxidante dos extratos de diferentes polaridades obtidos das diferentes formulações. Utilizando-se o método DPPH (1,1-difenil-2-picrilhidrazil) e o sistema ß-caroteno/ácido linoléico, não foi encontrada interação entre os componentes com AA presentes nos ingredientes. Apesar dos modelos obtidos não descreverem adequadamente a variação dos resultados, o manjericão foi identificado como o ingrediente de maior contribuição para a AA total do molho. Foi realizada análise sensorial para determinar a formulação melhor aceita dentre as possibilidades obtidas. A segunda fase consistiu em submeter a formulação determinada na fase 1 às análises de composição centesimal, quantificação dos compostos fenólicos totais e quatro métodos in vitro de avaliação da AA: método do poder redutor, sistema ß-caroteno/ácido linoléico, DPPH e ensaio em meio lipídico pelo aparelho Rancimat®. A formulação final pode ser considerada como uma boa fonte de antioxidantes naturais e portanto fazer parte de uma dieta saudável. / Recent evidences have shown that high consumption of vegetables, fruits and grains can reduce the risk of non-communicable diseases. The healthy properties of these foods have been related mostly to the presence of antioxidants, substances which are known as capable of decreasing the harmful effects of free radicals. The objective of this work was to develop a Pesto sauce formulation, based on the antioxidant properties of its main ingredients: sweet basil, Brazil nut and extra-virgin olive oil. The methodology was divided in two phases: The first one consisted in the evaluation of the interaction between the components with antioxidant activity (AA) present in the sauce\'s main ingredients, applying the response surface methodology with a mixture model. A centroid simplex plan was used, in which the response measured was the AA of the extracts of different polarities from the different formulations. By using the DPPH (1,1-diphenyl-2-picryhydrazyl) method and the ß-carotene/linoleic acid system, no interaction between the components with AA was detected. Although the models could not describe properly the response variation, sweet basil was identified as the main responsible for the total AA of the sauce. Sensory analysis was conducted to determine the most accepted formulation among the possibilities. The second phase consisted in submitting the formulation obtained in phase 1 to centesimal composition analysis, quantification of total phenolics and four in vitro AA methods: reducing power, DPPH method, ß-carotene/linoleic acid system and the Rancimat® method. The final formulation may be considered a good source of natural antioxidants and therefore be part of a healthy diet.
60

Otimização para a obtençao de extrato aquoso de tremoço branco (Lupinus albus L.) adicionado de suco de pitanga /

Botaro, Juliana Aparecida. January 2010 (has links)
Orientador: José Paschoal Batistuti / Banca: Rubens Monti / Banca: Alice Yoshiko Tanaka / Resumo: Recentemente, a indústria de alimentos está preocupada em desenvolver novos produtos, usando ingredientes inovadores, que promovam benefícios à saúde. O uso de proteínas de leguminosas como uma alternativa para a proteína animal tem sido estudada. O tremoço branco (Lupinus albus L.) apresenta elevada concentração de proteína e óleo, principalmente ácidos graxos insaturados e poliinsaturados, fibra alimentar, açúcares e vitaminas B1 e B2. Por outro lado, o tremoço não pode ser consumido diretamente porque possui alcaloides, que além de serem tóxicos, atribuem gosto amargo ao grão. Como a maioria dos alcaloides é solúvel em água, a quantidade de alcaloide do grão pode ser diminuída através de água corrente, fervente ou salmoura. Sucos de frutas são bastante consumidos no Brasil, especialmente no verão, não somente pelo sabor, mas como fonte de hidratação e por serem ricos em nutrientes. Os sucos de frutas tropicais conquistam cada vez mais o mercado consumidor, sendo o Brasil, um dos principais produtores. A pitanga, fruto da pitangueira (Eugenia uniflora L.) é uma planta frutífera nativa do Brasil (das regiões Sul e Sudeste e que tem se adaptado favoravelmente às condições climáticas e edáficas da região Nordeste), da Argentina e do Uruguai. A pitanga é uma fruta cuja polpa apresenta excelentes condições para industrialização, devido ao seu alto rendimento, aroma agradável e sabor exótico. O objetivo do presente estudo foi o de verificar, através da metodologia de superfície de resposta, as melhores condições para a utilização simultânea de extrato aquoso de tremoço branco e de suco tropical de pitanga, no desenvolvimento de uma bebida. Para tanto, as variáveis independentes foram representadas pelo volume de extrato aquoso de tremoço (mL) e pelo volume de suco de pitanga... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Recently, the food industry is concerned about developing new products, using innovative ingredients that promote health benefits. The use of vegetable protein as an alternative to animal protein is being studied. The white lupine (Lupinus albus L.) has high concentrations of protein and oil, especially non saturated fatty acids and polynonsaturated fats, dietary fiber, sugars and vitamins B1 and B2. On the other hand, the lupine bean can't be consumed straight because it has alkaloids which besides being toxic, add a bitter taste to the bean. As most alkaloids are water soluble, the amount of alkaloid in the beans can be reduced by running water, boiling or brine. Fruit juices are widely consumed in Brazil, especially in the summer, not only for their flavor, but as a source of hydration and because they are rich in nutrients. The tropical fruit juices are conquering the market more and more, with Brazil being one of the main producers in the world. The Pitanga (Eugenia uniflora L.) is the fruit of the Pitangueira, a native plant of southern Brazil (which has adapted positively to weather and soil conditions in the country's Northeast), Argentina and Uruguay. Pitanga is a fruit which pulp presents excellent conditions for industrialization, due to its high yield, pleasant aroma and exotic flavor. The aim of the present study was to verify, through the response surface methodology, the optimum conditions for the combined use of aqueous extract of white lupine and tropical pitanga juice in the development of a drink. Therefore, the independent variables were represented by the volume of aqueous extract of lupine (mL) and by the volume of pitanga juice (mL). The dependent variables (responses) were obtained through sensory test of acceptance ("appearance", "aroma", "taste" and "overall acceptability"). The combined... (Complete abstract click electronic access below) / Mestre

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