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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.
611

Développement d'un système in situ à base de tâches pour un code de dynamique moléculaire classique adapté aux machines exaflopiques / Integration of High-Performance Task-Based In Situ for Molecular Dynamics on Exascale Computers

Dirand, Estelle 06 November 2018 (has links)
L’ère de l’exascale creusera encore plus l’écart entre la vitesse de génération des données de simulations et la vitesse d’écriture et de lecture pour analyser ces données en post-traitement. Le temps jusqu’à la découverte scientifique sera donc grandement impacté et de nouvelles techniques de traitement des données doivent être mises en place. Les méthodes in situ réduisent le besoin d’écrire des données en les analysant directement là où elles sont produites. Il existe plusieurs techniques, en exécutant les analyses sur les mêmes nœuds de calcul que la simulation (in situ), en utilisant des nœuds dédiés (in transit) ou en combinant les deux approches (hybride). La plupart des méthodes in situ traditionnelles ciblent les simulations qui ne sont pas capables de tirer profit du nombre croissant de cœurs par processeur mais elles n’ont pas été conçues pour les architectures many-cœurs qui émergent actuellement. La programmation à base de tâches est quant à elle en train de devenir un standard pour ces architectures mais peu de techniques in situ à base de tâches ont été développées.Cette thèse propose d’étudier l’intégration d’un système in situ à base de tâches pour un code de dynamique moléculaire conçu pour les supercalculateurs exaflopiques. Nous tirons profit des propriétés de composabilité de la programmation à base de tâches pour implanter l’architecture hybride TINS. Les workflows d’analyses sont représentés par des graphes de tâches qui peuvent à leur tour générer des tâches pour une exécution in situ ou in transit. L’exécution in situ est rendue possible grâce à une méthode innovante de helper core dynamique qui s’appuie sur le concept de vol de tâches pour entrelacer efficacement tâches de simulation et d’analyse avec un faible impact sur le temps de la simulation.TINS utilise l’ordonnanceur de vol de tâches d’Intel® TBB et est intégré dans ExaStamp, un code de dynamique moléculaire. De nombreuses expériences ont montrées que TINS est jusqu’à 40% plus rapide que des méthodes existantes de l’état de l’art. Des simulations de dynamique moléculaire sur des système de 2 milliards de particles sur 14,336 cœurs ont montré que TINS est capable d’exécuter des analyses complexes à haute fréquence avec un surcoût inférieur à 10%. / The exascale era will widen the gap between data generation rate and the time to manage their output and analysis in a post-processing way, dramatically increasing the end-to-end time to scientific discovery and calling for a shift toward new data processing methods. The in situ paradigm proposes to analyze data while still resident in the supercomputer memory to reduce the need for data storage. Several techniques already exist, by executing simulation and analytics on the same nodes (in situ), by using dedicated nodes (in transit) or by combining the two approaches (hybrid). Most of the in situ techniques target simulations that are not able to fully benefit from the ever growing number of cores per processor but they are not designed for the emerging manycore processors.Task-based programming models on the other side are expected to become a standard for these architectures but few task-based in situ techniques have been developed so far. This thesis proposes to study the design and integration of a novel task-based in situ framework inside a task-based molecular dynamics code designed for exascale supercomputers. We take benefit from the composability properties of the task-based programming model to implement the TINS hybrid framework. Analytics workflows are expressed as graphs of tasks that can in turn generate children tasks to be executed in transit or interleaved with simulation tasks in situ. The in situ execution is performed thanks to an innovative dynamic helper core strategy that uses the work stealing concept to finely interleave simulation and analytics tasks inside a compute node with a low overhead on the simulation execution time.TINS uses the Intel® TBB work stealing scheduler and is integrated into ExaStamp, a task-based molecular dynamics code. Various experiments have shown that TINS is up to 40% faster than state-of-the-art in situ libraries. Molecular dynamics simulations of up to 2 billions particles on up to 14,336 cores have shown that TINS is able to execute complex analytics workflows at a high frequency with an overhead smaller than 10%.
612

In-situ Untersuchungen von zementgebundenen Baustoffen mittels röntgenographischer Verfahren

Schlegel, Moritz-Caspar 06 March 2013 (has links)
Die Materialeigenschaften und Dauerhaftigkeit von zementgebundenen Baustoffen hängen von den Hydratationsbedingungen und dem Wiederstand gegen chemische Angriffe während bzw. nach der Fertigstellung eines Bauwerkes ab. In dieser Arbeit wurden experimentelle Aufbauten entwickelt, um in diesen Zeiträumen von zementgebundenen Baustoffen die Änderungen des Phasenbestandes hochaufgelöst zu untersuchen. Sie basieren auf Röntgenbeugungsexperimente unter der Nutzung intensiver Synchrotronstrahlung. Dieses ermöglicht einen detaillierten Einblick in die Dynamik der Hydratationsprozesse im Frühstadium und die Änderung des Phasenbestandes durch alltägliche Lösungen. / The material properties and life time of cementitious materials depends on both hydration conditions and resistance against chemical attacks during and after the construction of buildings respectively. In this study, experimental setups were developed to investigate the changes of the phase composition with a high resolution during this different time periods of cementitious materials life. They based on X-Ray diffraction methods using intensive synchrotron radiation. This provides a detail view into the dynamics of the hydration processes at early ages and the change of the phase composition due to interaction with common solution.
613

Experimental Study of In Situ Combustion with Decalin and Metallic Catalyst

Mateshov, Dauren 2010 December 1900 (has links)
Using a hydrogen donor and a catalyst for upgrading and increasing oil recovery during in situ combustion is a known and proven technique. Based on research conducted on this process, it is clear that widespread practice in industry is the usage of tetralin as a hydrogen donor. The objective of the study is to find a cheaper hydrogen donor with better or the same upgrading performance. Decalin (C10H18) is used in this research as a hydrogen donor. The experiments have been carried out using field oil and water saturations, field porosity and crushed core for porous medium. Four in situ combustion runs were performed with Gulf of Mexico heavy oil, and three of them were successful. The first run was a control run without any additives to create a base for comparison. The next two runs were made with premixed decalin (5 percent by oil weight) and organometallic catalyst (750 ppm). The following conditions were kept constant during all experimental runs: air injection rate at 3.1 L/min and combustion tube outlet pressure at 300 psig. Analysis of the performance of decalin as a hydrogen donor in in-situ combustion included comparison of results with an experiment where tetralin was used. Data from experiments of Palmer (Palmer-Ikuku, 2009) was used for this purpose, where the same oil, catalyst and conditions were used. Results of experiments using decalin showed better quality of produced oil, higher recovery factor, faster combustion front movement and higher temperatures of oxidation. API gravity of oil in a run with decalin is higher by 4 points compared to a base run and increased 5 points compared to original oil. Oil production increased by 7 percent of OOIP in comparison with base run and was 2 percent higher than the experiment with tetralin. The time required for the combustion front to reach bottom flange decreased 1.6 times compared to the base run. The experiments showed that decalin and organometallic catalysts perform successfully in in situ combustion, and decalin is a worthy replacement for tetralin.
614

The study of glucose-6-phosphate dehydrogenase (G6PD) gene regulation in HepG2 cells by glucose induction and the study of G6PD mRNA localization by fluorescent in situ hybridization (FISH)

Griffith, Brian Nelson. January 2002 (has links)
Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains viii, 100 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 80-96).
615

Tjärsandsindustrins miljöpåverkan : Alberta, Kanada

Kjelleros, Fredrik January 2015 (has links)
In Alberta, Canada, amongst its mixture of sand, clay, water and other minerals, the tar sand’s heavy and viscous component bitumen, a thick, sticky form of crude oil is extracted through two methods; open-pit mining for shallower deposits (<75 m), and in situ for deeper deposits (>75 m). This degree project consists of a comparison between these two extraction methods impact on air, nature and water, which all have been evaluated by reviewing and analyzing literature. Studies showed that in situ methods cause a higher impact on air than open-pit mining, through higher emissions of greenhouse gases and sulfur dioxide (SO2), and will surpass the carbon dioxide (CO2) emissions caused by the open-pit mines when the shallower, more accessible tar sands dwindle. Open-pit mining causes a higher impact on water due to its large tailing ponds that causes leakage of processing water and fine tailings, polyaromatic hydrocarbons (PAH: s) and these 13 following elements considered priority pollutants (PPE) by the US Environmental Protection Agency (EPA); antimony (Sb), arsenic (As), beryllium (Be), lead (Pb), cadmium (Cd), copper (Cu), chromium (Cr), mercury (Hg), nickel (Ni), selenium (Se), silver (Ag), thallium (Tl) and zinc (Zn). However studies remain unclear whether or not in situ methods are worse due to underground tailing ponds. Finally, when it comes to nature, open-pit mining causes a more direct environmental impact through deforestation, drainage of peat and wetland, and blasting of rock. In situ methods however, seem to cause more of a long term environmental impact through fragmentation. Dividing the landscape into smaller units through roads, wells, pipelines and seismic lines, leads to domestic biodiversity and homogenization of flora and fauna as unfavorable conditions is created for the nature’s wildlife. In conclusion, in situ methods causes a bigger impact on air than open-pit mining, while open-pit mining causes a bigger impact on water. Due to lack of time and resources, more research about the direct impact on nature is needed to fully evaluate which of the two extraction methods causes the least environmental impact.
616

PAPRASTOJO KMYNO (CARUM CARVI L.) LIETUVOS POPULIACIJOS FENOTIPINĖ IR GENETINĖ ĮVAIROVĖ / PHENOTYPIC AND GENETIC DIVERSITY OF CARAWAY (CARUM CARVI L.) POPULATION IN LITHUANIA

Petraitytė, Nijolė 16 January 2006 (has links)
In 1996-2000 during expeditions were found and described 123 Carum carvi habitats. Mostly common caraway is found in pasture type habitats of Cynosurion cristati confederation communities. Plants of Carum carvi cenopopulations are characterized by wide diversity of phenotypic traits strongly influenced by ecological conditions and anthropogenic activity in natural habitats. The most stable parameters are weight of 1000 fruit and biochemical composition of essential oil. Essential oil synthesis in fruits is positively affected by warm and dry weather at the stage of caraway flowering – fruit ripening, carvone content – by warm and wet weather. The identified morphological types of Carum carvi leaves were as follows: normal, dill and parsley. Early-season caraway forms in comparison to others distinguished for the lowest height, fruit weight and total yield, but had the highest carvone content in fruit essential oil. Pink petals are characteristic for early-season caraway cenopopulations. White petal color, greater pigments amount in leaves, higher fruit productivity, as well as essential oil and carvone output characterize medium late and late forms. Various caraway genotypes with different levels of leaf carotinoids, chlorophyll content and ratio, anthocianins amount in petals, different reaction to cold and lighting stress reveal specific adaptive plasticity of caraway. Caraway intercenopopulation genetic diversity was determined at the molecular level.
617

Les relations entre la scène et le cinéma dans le spectacle d'avant-garde : une étude intermédiale et in situ de Relâche de Picabia, Satie et Clair

Bouchard, Karine January 2009 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal / Pour respecter les droits d'auteur, la version électronique de cette thèse ou ce mémoire a été dépouillée, le cas échéant, de ses documents visuels et audio-visuels. La version intégrale de la thèse ou du mémoire a été déposée au Service de la gestion des documents et des archives de l'Université de Montréal.
618

The challenge of informal settlement upgrading : Breaking new ground in Hangberg, Cape Town?

Ehebrecht, Daniel January 2014 (has links)
Despite its many challenges and limitations the concept of in situ upgrading of informal settlements has become one of the most favoured approaches to the housing crisis in the ‘Global South’. Due to its inherent principles of incremental in situ development, prevention of relocations, protection of local livelihoods and democratic participation and cooperation, this approach is often perceived to be more sustainable than other housing approaches that often rely on quantitative housing delivery and top down planning methodologies. While this study does not question the benefits of the in situ upgrading approach, it seeks to identify problems of its practical implementation within a specific national and local context. The study discusses the origin and importance of this approach on the basis of a review of international housing policy development and analyses the broader political and social context of the incorporation of this approach into South African housing policy. It further uses insights from a recent case study in Cape Town to determine complications and conflicts that can arise when applying in situ upgrading of informal settlements in a complex local context. On that basis benefits and limitations of the in situ upgrading approach are specified and prerequisites for its successful implementation formulated. / Trotz vieler Herausforderungen und Beschränkungen gilt das Konzept des in situ upgrading informeller Siedlungen als eine der wichtigsten Herangehensweisen an die Wohnraumkrise im „globalen Süden“. Aufgrund seiner immanenten Prinzipien einer schrittweisen Entwicklung an Ort und Stelle, der Vermeidung von Umsiedlungen, dem Erhalt lokaler Existenzgrundlagen sowie demokratischer Beteiligung und Kooperation, wird oftmals angenommen, dass diese Herangehensweise nachhaltiger ist, als eine quantitativ ausgerichtete Wohnraumversorgung und Top-Down-Planungsansätze. Während diese Studie die Vorteile des in situ upgrading nicht in Frage stellt, zielt sie darauf ab, Probleme der praktischen Umsetzung dieses Ansatzes in einem spezifischen nationalen und lokalen Kontext zu identifizieren. Die Studie diskutiert die Herkunft und die Bedeutung des in situ upgrading auf der Grundlage einer Rückschau auf die Entwicklung internationaler Wohnraumpolitik und analysiert den politischen und sozialen Kontext der Einbettung dieses Ansatzes in die südafrikanische Wohnraumpolitik. Darüber hinaus macht sie sich Einblicke einer kürzlich durchgeführten Fallstudie in Kapstadt zunutze, um Probleme und Konflikte zu erfassen, die bei der Umsetzung des in situ upgrading in einem komplexen lokalen Kontext entstehen können. Auf dieser Grundlage werden die Vorteile wie auch die Beschränkungen des in situ upgrading näher spezifiziert und zentrale Voraussetzungen für eine erfolgreiche Umsetzung des Konzeptes formuliert.
619

In situ bioremediation and natural attenuation of dinitrotoluenes and trinitrotoluene

Han, Sungsoo 09 June 2008 (has links)
Contamination of soils and groundwater with nitroaromatic compounds such as 2,4,6-trinitrotoluene (TNT) and dinitrotoluenes (DNTs) has drawn considerable attention due to widely distributed contamination sites and substantial efforts for cleanup. Two isomers of DNT, specifically 2,6-dinitrotoluene (2,6-DNT) and 2,4-dinitrotoluene (2,4-DNT), occur as soil and groundwater contaminants at former TNT production sites. The discovery of bacteria that use DNT isomers as electron donors has encouraged bioremediation at contaminated sites. Current work is extending the existing engineered bioremediation to naturally occurring in situ biodegradation and focuses on the application of natural attenuation (NA) as a remediation strategy for residual DNT at contaminated sites. More specifically this research evaluated factors influencing in situ bioremediation of DNTs and TNT in surface soils, vadose zones, and saturated medium. Applications involving surface soils and vadose zones investigated the potential of water infiltration to promote in situ bioremediation. Studies in saturated media were more applicable to NA. Factors that were also considered in studies conduced included: 1) the presence and distribution of degrading microbes in field soils (Barksdale, WI); 2) the dissolution and bioavailability of contaminants in historically contaminated soils; and 3) the effect of mixtures of contaminants (i.e., DNTs and TNT) on biodegradation processes. This research provided information useful for practitioners considering an in situ bioremediation NA as a remedial solution for contaminated sites. Under the condition simulating downflow of surface waters or rainwater, the rapid rate of DNT degradation could be facilitated by the availability of oxygen in the soil gas without concern of toxicity (i.e., nitrite evolution and pH drop) and addition of nutrients. As a result, in situ bioremediation or NA should be strongly considered as a remedial option for Barksdale soils and similar sites where relatively low concentrations of DNT isomers are present as contaminants. At TNT contaminated sites TNT was not mineralized by indigenous microorganisms despite oxidative biotransformation, and mixed culture capable of growth on DNT also could not develop the mineralization of TNT during DNT degradation. This suggests that the mixtures of contamination did not improve the potential for in situ TNT bioremediation.
620

Desenvolvimento e avaliação de um método in vitro para estimar a degradabilidade das proteínas no rúmen / Development and evaluation of an in vitro method to estimate the degradation of proteins in the rumen

Härter, Carla Joice 13 February 2009 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / A set of assays was carried out to develop a method for estimating ruminal degradation of proteins based on ammonia production in vitro. Samples of soybean meal, meat and bone meal, ryegrass (Lolium multiflorum) and cynodon (Cynodon dactilon var. Dactylon) were incubated by using the procedures of the in vitro/gas method. The effects of sample amount; starch inclusion to correct for ammonia uptaked by bacteria; nitrogen concentration in buffer solution and preview treatment of samples for soluble nitrogen extraction were evaluated. Short-time in vitro assays were also carried out to estimate degradation rate or solubilization rate of soluble fraction of nitrogen. Results of protein degradation obtained for some samples incubated in vitro were compared to those obtained from in situ and in vivo assays carried out in parallel. Results of protein degradation of different samples were not affected by sample size (15 mg N/ sample 1 g of sample) whereas degradability and dagradation rate of ryegrass protein, without starch correction, was negativelly affected by exclusion of ammonium bicarbonate from buffer solution (P<0,05). The preview extraction of soluble fraction of samples affected (P<0.05) protein degradation only of the ryegrass and soybean meal samples. Estimates of protein degradation for concentrate samples were not affected by starch inclusion. However, starch inclusion increased (P<0.05) protein degradation for ryegrass samples. Determination coefficient (r²) of regressions relating ammonia concentration and incubation time were usually high (above 0.80). Protein degradability of soybean meal, meat and bone meal and ryegrass samples were lower by in vitro than by in situ method (P<0.05). In turn, protein degradability of ryegrass and cynodon samples estimated in vitro was similar to obtained in vivo. In conclusion, although it needs more consistent validation, the in vitro/gas method might be an useful tool for estimating rumen degradabilty of proteins. / Foi conduzido um conjunto de ensaios in vitro com o objetivo de desenvolver um método para estimar a degradação de proteína no rúmen baseado na liberação de amônia no meio de incubação. Foram incubadas amostras de farelo de soja, farinha de carne e ossos, azevém (Lolium multiflorum) e cynodon (Cynodon dactilon var. Dactylon) utilizando-se os procedimentos da técnica in vitro/gases. Foi avaliado o efeito da quantidade de amostra incubada, da inclusão de amido para corrigir a fração de nitrogênio capturado pelas bactérias, do teor de nitrogênio na solução tampão e do tratamento prévio das amostras para remoção da fração solúvel do nitrogênio. Foram conduzidos também ensaios in vitro de curta duração para medir a taxa de degradação ou de solubilização da fração solúvel da proteína das amostras. Os resultados de degradação protéica obtidos em algumas amostras incubadas in vitro foram comparados com os obtidos em ensaios in vivo e in sito, que foram conduzidos paralelamente. A degradação da proteína de diferentes amostras não foi afetada pelo tamanho de amostra (15 mg N/ amostra 1 g de amostra), entretanto a degradabilidade e a taxa de degradação protéica do azevém, sem correção de amido, foram negativamente afetadas pela exclusão do bicarbonato de amônio da solução tampão (P<0,05). O tratamento prévio da amostra interferiu (P<0,05) nos resultados de degradação protéica das amostras de azevém e farelo de soja, mas não da farinha de carne. Em geral, a inclusão de amido para correção da amônia utilizada pelos microorganismos, resultou em maiores valores de degradabilidade da proteína do azevém (P<0,05), mas não das outras amostras. O coeficiente de determinação (r²) das estimativas da taxa de degradação, calculada com base na variação da concentração de amônia no meio ao longo do tempo de incubação, foram geralmente altos (superiores a 80%). As degradabilidades efetivas da proteína das amostras de farelo de soja, farinha de carne e azevém, estimadas pelo método in vitro foram inferiores às estimadas pelo método in situ (P<0,05). Por outro lado, a degradabilidade efetiva da proteína de amostras de azevém e Cynodon estimada pelo método in vitro não diferiu dos valores obtidos in vivo com ovinos fistulados no duodeno. Em conclusão, o método in vitro/gases pode ser uma ferramenta útil para estimar a degradabilidade ruminal das proteínas, embora ainda necessite ser melhor validado com estudos in vivo.

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