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Konrad, Stephanie, i Daniela Polziehn. "The Natural Solution? : A Qualitative Study on Attitudes towards Natural Care Products for Men of Generation Y". Thesis, Internationella Handelshögskolan, Högskolan i Jönköping, IHH, Företagsekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-30387.
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Smethurst, Christopher. "A Finite Element Solution of the Natural Convection Problem in 3D". Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517825.
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Donini, Mariovane Sabino. "Numerical solution for the droplet combustion". Universidade Federal do Pampa, 2017. http://dspace.unipampa.edu.br:8080/jspui/handle/riu/1955.
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In the present work, vaporization and combustion of an isolated fuel droplet at diferente ambient temperatures are examined numerically in order to analyze the effect of buoyancy force on the flame. Generally, fuel droplets in combustion devices are so small that the influence of buoyancy force on vaporization and combustion of droplets is negligible. On the other hand, fuel droplets in experimental devices are affected by the buoyancy force due to their diameters being around or more than 1 mm. To reduce the buoyancy effects, expensive experimental studies are performed in microgravity ambient (drop-tower or out of space). In normal-gravity conditions, the buoyancy force is induced by temperature gradient on ambient atmosphere. The buoyancy is positive in regions of hot gases and negative in regions of cold gases compared with the ambient atmosphere gas. Hot gases move upward and cold gases downward. Playing with the positive buoyancy force of hot gases around the flame and with the negative (cold) buoyancy force of cold gases around the droplet via ambient atmosphere temperature, it is possible to modify the flame shape. In the numerical simulations, incompressible Navier–Stokes equations along with mixture fraction and excess enthalpy conservation equations are solved using a finite volume technique with a uniform structured grid. An artificial compressibility method was applied to reach steady state solutions. The numerical predictions have been compared with analytical results for a zero gravity condition, showing good agreement. For normal gravity condition the numerical results showed that when the ambient temperature increases, the velocity gradient and buoyancy source term decreases. Despite that, the flame increased in all directions. The results have also shown that increasing the ambient temperature, decreases the temperature gradient in the flame, which ends up affecting the flame position.
No presente trabalho, a vaporização e a combustão de uma gota de combustível isolada a diferentes temperaturas ambiente são examinadas numericamente para analisar o efeito da força de flutuação na chama. Geralmente, as gotículas de combustível em dispositivos de combustão são tão pequenas que a influência da força de flutuação na vaporização e na combustão de gotículas é insignificante. Por outro lado, as gotículas de combustível em dispositivos experimentais são afetadas pela força de flutuabilidade devido ao seu diâmetro em torno de ou mais de 1 mm. Para reduzir os efeitos de flutuabilidade, estudos experimentais caros são realizados em ambiente de microgravidade (drop-tower ou fora do espaço). Em condições de gravidade normal, a força de flutuação é induzida por gradiente de temperatura na atmosfera ambiente. A flutuabilidade é positiva em regiões de gases quentes e negativas em regiões de gases frios em comparação com o gás atmosférico ambiente. Os gases quentes movem-se para cima e os gases frios para baixo. Jogando com a força de flutuação positiva dos gases quentes ao redor da chama e com a força de flutuação negativa (fria) dos gases frios ao redor da gota através da temperatura da atmosfera ambiente, é possível modificar a forma da chama. Nas simulações numéricas, as equações de Navier-Stokes incompressíveis juntamente com a fração de mistura e as equações de conservação de entalpia em excesso são resolvidas usando uma técnica de volume finito com uma grade estruturada uniforme. Foi aplicado um método de compressibilidade artificial para alcançar soluções de estado estacionário. As previsões numéricas foram comparadas com resultados analíticos para uma condição de gravidade zero, mostrando boa concordância. Para a condição de gravidade normal, os resultados numéricos mostraram que, quando a temperatura ambiente aumenta, o gradiente de velocidade e o termo da fonte de flutuação diminuem. Apesar disso, a chama aumentou em todas as direções. Os resultados também mostraram que aumentar a temperatura ambiente, diminui o gradiente de temperatura na chama, o que acaba afetando a posição da chama.
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Ogunrobo, Emmanuel Osarumwense. "Analysis of hydrocarbon solubility in amine solution used for natural gas processing". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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This Thesis comprises of experimental and the theoretical work done on the analysis of hydrocarbon solubility in amine solutions used for natural gas processing.
The objective of this study is the solubility of hydrocarbons in different Amine solutions and the comparison of the results obtained, in order to understand their behaviour in applications related to Natural Gas processing. From solubility knowledge indeed several informations of interest could be obtained such as: i) quantification of possible losses of hydrocarbons during amine treatment ii) evaluation of the amount of these components reaching the stripper and iii) determination of the additional work to be done for purification of the amine solutions after the absorber.
Data for the solubility of the different hydrocarbon and Amines are indeed important for proper modelling of absorption columns and the strippers.
The peculiarity of the study is that in addition to the analysis of solubility on pure and mixed amine solution also the solubility of loaded amine solutions will be considered, i.e. Amine solution mixed with acid gas like CO2 and/or H2S. Indeed, while there had been previous measurements made on this project, but they were basically for the non-loaded amine solution, giving therefore only partial information on this topic.
This experiment is carried out at the laboratories of the group of Chemical Engineering at Aalto School of Chemical Technology and written at the University of Bologna Italy.
The chief apparatus for this study among others are BBQ apparatus with a capacity of 30 vials and GC Agilent 7890 B.
The following Hydrocarbons were used: Benzene, Ethylbenzene, Toluene, Hexane, Cyclohexane and 2,2,4-Trimethylpentane and the following amines solutions: Diglycolamine (DGA), N-methyl-diethanolamine(MDEA), Monoethanolamine(MEA), Di-Ethanolamine(DEA), and Piperazine.
Tests were carried out at (define T and P) and at H2S and CO2 loading level ranging from about 0.15 to 0.45
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Rhys, Natasha Hazel. "Exploring the structural properties of natural and synthetic biological molecules in aqueous solution". Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/11248/.
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Peptoids are synthetic mimics of naturally-occurring peptides (the natural building blocks of proteins). These interesting building blocks are more resistant to temperature, pH and solvent denaturation, and possess a more exible backbone compared to their peptide counterparts. As a result, peptoids are emerging as promising biomimetic materials for a range of applications. Despite this potential, very little is known about the intermolecular interactions which determine their stability and solubility, including hydrogen-bonding, hydrophobic interactions and hydration properties, as well the structural properties of the individual imino acid blocks that make them. This thesis presents neutron diffraction experiments coupled with isotopic substitution and computational modelling to complete a structural study on a model imino acid in aqueous solution. The focus here has been on glutamine, a molecule that is capable of forming multiple hydrogen bonds and is thought to self-assemble through preferential side-chain hydrogen bond interactions, making it an interesting model system. Furthermore, glutamine is important in many biochemical processes and its presence has been associated with a number of neurodegenerative diseases. By probing the structural properties of the model system in aqueous solution and of its amino acid equivalent, L-glutamine, it has been possible to uncover details of important intermolecular interactions that govern the properties of these biomolecules. The interactions of the model imino acid have also been observed with respect to temperature and concentration and compared to a naturally-occurring imino acid, sarcosine, to determine the impact of side chain on imino acid interactions. This work also serves as a reference for completing structural studies on such biomolecules, covering methodological benefits and limitations. This is the necessary first step in building a framework to understand the self-assembly and driving forces in more complex peptoid and peptide structures and serves as a reference for completing neutron studies on natural and synthetic biomolecules.
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Comuni, Federica. "A natural language processing solution to probable Alzheimer’s disease detection in conversation transcripts". Thesis, Högskolan Kristianstad, Fakulteten för naturvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hkr:diva-19889.
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This study proposes an accuracy comparison of two of the best performing machine learning algorithms in natural language processing, the Bayesian Network and the Long Short-Term Memory (LSTM) Recurrent Neural Network, in detecting Alzheimer’s disease symptoms in conversation transcripts. Because of the current global rise of life expectancy, the number of seniors affected by Alzheimer’s disease worldwide is increasing each year. Early detection is important to ensure that affected seniors take measures to relieve symptoms when possible or prepare plans before further cognitive decline occurs. Literature shows that natural language processing can be a valid tool for early diagnosis of the disease. This study found that mild dementia and possible Alzheimer’s can be detected in conversation transcripts with promising results, and that the LSTM is particularly accurate in said detection, reaching an accuracy of 86.5% on the chosen dataset. The Bayesian Network classified with an accuracy of 72.1%. The study confirms the effectiveness of a natural language processing approach to detecting Alzheimer’s disease.
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Li, Bo. "Synthesis, Kinetics and Mechanisms of Designer and Natural Product Antioxidants: From Solution to Cells". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34335.
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Lipid peroxidation has been implicated in the onset and progression of many degenerative diseases, including cardiovascular disease, Alzheimer’s disease and cancer. Accordingly, for more than 50 years, considerable effort has been devoted to the design of synthetic compounds or the discovery of natural products that can slow lipid peroxidation. Despite the enormous investments made to date, no clear antioxidant strategies have emerged for the treatment and/or prevention of degenerative disease. We argue that this is because of a lack of fundamental understanding of the chemical reactivity of these compounds in relevant contexts. Herein, we describe studies of our optimized synthetic radical-trapping antioxidant (RTA) – the tetrahydronaphthyridinols (THNs). We first present the synthesis of a series of THN analogs of α-tocopherol (Nature’s premier lipid-soluble radical-trapping antioxidant) with varying sidechain substitution and then demonstrate how systematic changes in the lipophilicity of these potent antioxidants impact their peroxyl radical-trapping activities in lipid bilayers and mammalian cell culture. Their regenerability by water-soluble reductants in lipid bilayers, binding to human tocopherol transport protein (hTTP), and cytotoxicity were also evaluated to provide insight on whether this type of antioxidant can be potentially pushed toward animal studies.
We also describe analogous studies of natural products such as the garlic-derived thiosulfinate allicin and the grape-derived polyphenol resveratrol. These compounds have attracted significant attention in the past 20 years due to their purported health benefits, which are often ascribed to their purported radical-trapping activities. To date, systematic studies on their radical-trapping activities in solution, lipid bilayers and mammalian cells have been lacking. We have determined that allicin and petivericin, while effective RTAs in solution, are not so in lipid bilayers. Moreover, the compounds are not antioxidants in cell culture, but instead kill the cells. Similarly, resveratrol and its dimers pallidol and quadrangularin A, are found to be inefficient RTAs in lipid bilayers. Our studies to date rather suggest that they autoxidize readily to produce hydrogen peroxide, which may induce expression of phase 2 antioxidant enzymes, affording cytoprotection. Our insights underscore the need for systematic studies of antioxidant activity in multiple contexts.
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Talbot, James David Ralph. "The conductivity of carbonate and phosphate species in aqueous solution and in some related natural waters". Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280559.
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Jonsson, Åsa. "Enhancement of Dry Content in Coating Solution for Functional Packaging". Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-16576.
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The main goal for a packaging is to protect the product inside. Typical packaging nowadays is made of layers of paper and barriers consisting of plastics or aluminum foil. A problem with the barrier used today is the environmental thinking. Xylophane® is an environmental friendly and biodegradable alternative to the current barrier material used in packaging. It consists of the natural carbohydrate xylan and additives. Xylophane® is an efficient barrier to oxygen, grease and aroma and can prolong the shelf life of sensitive food.
The raw material xylan is water soluble and Xylophane® can be coated on paper, board and plastics without using other solvents. A problem with the drying process is the amount of energy needed and the consumption needs to be decreased. Also, the drying capacity of the equipment to be used is often limited and the amount of water to be dried off is critical for the success of the coating process. By increasing the dry content of Xylophane® without increasing the viscosity too much, the drying process can be more effective. In this thesis, studies were made of using a filler as an additive to increase the dry content without destroying the barrier properties.
With an experimental design, a suitable relationship between the ingredients xylan (X), plasticizer (P) and filler (F) was found. Xylan is the main component and is needed to get a good oxygen barrier. The plasticizer decreases the oxygen barrier properties but is needed to make the material more flexible. The filler is positive for the barrier properties. The chosen composition was X:P = 7:3 and X:F = 1:1. Some extra experiments were made to find a reasonable value of the dry content. Dry contents around 18 % work well with temperatures at and above 45°C, but to manage to perform coating at room temperature the dry content needs to be lower.
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Heeren, Alexander Heeren. "Identifying the Problem or Identifying with the Solution?The Role of Motivated Reasoning and Identity Politics in Environmental Science". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1468073451.
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Nikolkina, Irina. "Modélisation des écoulements de gravité et des ondes longues : application à l'évaluation des risques de catastrophes naturelles dans les Antilles françaises". Thesis, Antilles-Guyane, 2011. http://www.theses.fr/2011AGUY0435/document.
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La thèse est consacrée à la recherche des catastrophes marines (tsunamis, ondes de tempête) dans les Antilles françaises, en utilisant des modèles analytiques et numériques de mécanique des fluides. L'accent est mis sur le développement de modèles de mouvement de glissements de terrain et des vagues causées par ces glissements. Le modèle le plus simple du glissement de terrain «solide block» est utilisé pour évaluer les caractéristiques des flux pyroclastiques du volcan Soufrière-Hills (Montserrat). Un modèle plus complexe de modélisation de glissement de terrain (modèle de Savage-Hutter) a été étudié analytiquement, donnant ainsi une nouvelle famille de solutions exactes décrivant le mouvement de l'écoulement par gravité non linéaire dans une vallée ou dans un canyon sous-marin. Le modèle comprend des ondes simples (Riemann waves),le cas d'un barrage qui cède (dam-break problem), des solutions auto-similaires dans la M-fonne et « chapeaux paraboliques ». Grâce à la théorie linéaire de l'eau peu profonde nous avons étudié le processus de génération de tsunamis par des glissements de terrain de volume variable, se déplaçant à une vitesse variable dans un bassin de profondeur variable. Dans le cas d'un fond marin particulier (cas sans "réflexion"), les phénomènes de résonnance ont été étudiés dans un bassin à profondeur variable. Nous avons utilisé des méthodes numériques pour la résolution non-linéaire des équations des eaux peu profondes afin d'analyser des catastrophes marines réelles (les ondes de tempête causées par le cyclone Lili en 2002, le tsunami volcanique de 2003 à Montserrat) et probables (un tsunami prés des côtes de la Martinique). Des données sur les catastrophesThe dissertation is devoted to research in the field of marine natural hazards (tsunamis, storm surges) in the French West Indies, using analytical and numerical models of fluid mechanics. Emphasis is placed on the development of models of landslide motion and generated tsunami waves. The simple "solid block" model is used to evaluate the characteristics of pyroclastic flow Soufriere Hills volcano (Montserrat). The "fluid model" of a landslide (so called Savage-Hutter model) is studied analytically; within this model a new family of exact solutions that describe the motion of nonlinear gravity flow in a valley or underwater canyon is found: nonlinear Riemann wave, dan break problem, self-similar solutions (M - wave and parabolic cap). In the framework of the linear shallow water theory the process of generation of tsunami waves by landslides of variable volume moving with variable velocity above the basin of variable depth is studied. For the specific bottom profile ("reflectionless" one) the resonant phenomena is investigated in the basin of variable depth. Numerical methods are used to analyze marine hazards: historical (storm surges, caused by Cyclone LILI in 2002; volcanic tsunami 2003 on Montserrat) and possible events (possible tsunami of the coast of Martinique). Various data on marine natural disasters are obtained during field surveys (volcanic tsunami in 2003, stonn surges caused by Hurricane Dean in 2007). Designed catalogs of tsunamis and storm surges are created based on results of numerical modeling and field studies; some statistical analysis is perfomed
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Armagan, Emre. "Decomposition algorithms for global solution of deterministic and stochastic pooling problems in natural gas value chains". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/46629.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Includes bibliographical references (leaves 153-158).
In this thesis, a Benders decomposition algorithm is designed and implemented to solve both deterministic and stochastic pooling problems to global optimality. Convergence of the algorithm to a global optimum is proved and then it is implemented both in GAMS and C++ to get the best performance. A series of example problems are solved, both with the proposed Benders decomposition algorithm and commercially available global optimization software to determine the validity and the performance of the proposed algorithm. Moreover, a two stage stochastic pooling problem is formulated to model the optimal capacity expansion problem in pooling networks and the proposed algorithm is applied to this problem to obtain global optimum. A number of example stochastic pooling problems are solved, both with the proposed Benders decomposition algorithm and commercially available global optimization software to determine the validity and the performance of the proposed algorithm applied to stochastic problems.
by Emre Armagan.
S.M.
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Ndayambaje, Guillaume. "Sorption properties of natural zeolites for the removal of ammonium and chromium ions in aqueous solution". University of the Western Cape, 2011. http://hdl.handle.net/11394/5425.
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>Magister Scientiae - MScThere are huge amount of natural clinoptilolite available in South Africa which can be utilised for wastewater treatment of ammonia and chromium if their characteristics are properly known. However, these deposits have not been well characterised but in this study, the untreated clinoptilolite materials were fully characterised using techniques such as SEM-EDS, HRTEM-SAED, XRD, XRF, FTIR and BET. After acid pretreatment with several extractions, the pretreated samples were again characterised using the above mentioned techniques. These pretreated materials were used for NH₄⁺ and Cr³⁺ adsorption of wastewater. The three natural South African clinoptilolite samples used in this study were from ECCA Holdings (ESC and EHC samples) and Pratley (PC sample) deposits obtained from Western Cape and KwaZulu-Natal Province respectively. This study revealed that the chemical composition and mineral phases of South African clinoptilolites vary considerably from site to site, even clinoptilolite mined from the same deposit sites. The XRD analyses showed that Pratley clinoptilolite (PC) was the most pure clinoptilolite sample (81.41 %) compared to the purity of EHC (67.88 %) and ESC (44.0 %) sample. The ECCA Holdings untreated clinoptilolite samples contained dense phases such as quartz which was not found in Pratley sample. Quartz was found to be the most dominant impurity in both ECCA Holding sample. The cation exchange capacity (CEC) of ESC, EHC and PC samples were found to be 1.23, 1.81 and 2.90 meq/g respectively and these results were compared to that of XRF analyses. The acid solutions of 0.02 and 1.0 M HCl were used to pretreat natural clinoptilolite to determine the optimum acid concentration and number of extractions required to fully replace the exchangeable cations. The pretreatment results showed that 0.02 M HCl was the optimum acid concentration for acid pretreatment of clinoptilolite samples. Between 7 and 22 extractions were required to remove Na⁺, K⁺, Ca²⁺ and Mg²⁺ without causing much dealumination of the framework. Sodium ion was found to be weakly bound cation in the clinoptilolite framework, since it could be completely exchanged by H⁺ after 7 extractions with 0.02 M HCl acid solution. Potassium ion was found to be strongly bound in the clinoptilolite framework since it could not be completely exchanged during the acid pretreatment process even after 22 extractions. The HRTEM-SAED and BET results showed that ESC, EHC and PC were all polycrystalline and microporous materials respectively. It was found that the adsorption capacity of the treated Pratley clinoptilolite sample was increased by 36 % for NH₄⁺ removal, compared to that of the untreated PC sample. The adsorption study results showed that the pretreatment of clinoptilolite samples using 150 mL volumes of 0.02 M HCl with 7 acid extractions at 25 °C for ESC pretreated and EHC pretreated. The pretreatment of PC sample at 22 extractions could remove high percentage of NH₄⁺ (98.11 %) within a short contact time of 10 min. The pretreated Pratley clinoptilolite sample was found to be the best NH₄⁺ adsorbent (98.11 % NH₄⁺ removal) compared to EHC treated (93.89 % NH₄⁺ removal) and ESC treated (75.00 % NH₄⁺ removal) clinoptilolite samples. However, acid-pretreated Pratley clinoptilolite did not sufficiently remove Cr³⁺ (16.10 %) from synthetic wastewater showing that it is not a good adsorbent for this particular metal ion removal. Despite several studies that have been conducted on clinoptilolite, no study has been carried out on the pretreatment and comparison of sorption capacity of different South African clinoptilolites for the removal of NH₄⁺ from wastewater. This study has been able improve on the acid-pretreatment procedure for clinoptilolite. This study demonstrated that it is not only the acid concentration that is important but also the number of extractions needed to remove all the exchangeable cations from the clinoptilolite framework. This study has also been able to prove that South African clinoptilolite can treated ammonia from wastewater.
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Romashko, A. S. "Green economy as a solution of ecological problems". Thesis, Sumy State University, 2014. http://essuir.sumdu.edu.ua/handle/123456789/45223.
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Every year the world’s GDP increases, but mainly due using of natural resources. Every year demand for environmental resources as water wood is increasing. Climate change, depletion of natural resources, increasing energy prices are some of the most important problems. The solution to these problems may be a shift to a "green economy." A new branch of economics called "green economy" is designed to improve the nature of the country. "Green Economy" - a new stage of development, which involves new technologies, ecosystems, the creation of "pure transport", organic food.
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Beltz, Morgan. "The Declining Natural Fish Stock: A Proposed Solution to Public Fear and Perceptions of Genetically Modified Fish". Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/cmc_theses/765.
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The global fish population is declining. Aquaculture production is saturated and the global fish stock is operating at an unsustainable level. Genetically modified (GM) fish is a potential solution to relieve the natural fish stock, if the FDA grants the approval. The global fish population is harmed by environmental conditions and the inability for fish to adapt to changing conditions and human interactions. Genetic modification is a growing technology that has the ability to alleviate the fishing industry by modifying fish to grow faster, be disease tolerant, eat plant-based food, and be more nutritious. However, the approval process has been halted by complications in the approval process and government leaders responding to public fears and concerns of the safety of genetically modified fish. This thesis reviews the background of the fishing industry, concerns over GMOs, and analyzes the politics preventing the approval of GM fish. Lastly, this thesis recommends six approaches the FDA should mandate to reassure the public of the safety of GM fish.
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de, las Heras Reverte Víctor. "Evaluation of natural materials in Sustainable Buildings : A potential solution to the European 2050 long-term strategy". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-300115.
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Today, buildings consume 40% of total energy demand in the EU and are responsible for 36% of GHG emissions. For this reason, and due to the delicate situation of climate change that planet Earth is experiencing, solutions are being sought to make the building sector more sustainable. In the current project, the use of natural materials has been chosen as a solution in line with the EU 2050 long-term strategy. This research broadens the knowledge on sustainable building with natural materials as an alternative to conventional construction. To this end, first, an extensive state of the art has been carried out to gather information and identify research gaps on natural building materials and energy efficiency, proving the suitability of natural construction materials. Special emphasis has been put on straw bale construction and rammed earth construction, which have been studied individually. In addition, geometrically identical building models of both building techniques have been developed and simulated in Stockholm and Valencia in order to see how they would perform in different climates. Total energy demand for the straw-bale building of 140.22 kWh/(m2·year) in the case of Stockholm and 37.05 kWh/(m2·year) in the case of Valencia has been obtained. For the rammed earth building, a total demand of 301.82 kWh/(m2·year) has been obtained in Stockholm and 78.66 kWh/(m2·year) in Valencia. Once passive measures are applied in the different models, a reduction in demand for the straw bale building of 77.8% and 36.3% has been achieved for Stockholm and Valencia, respectively. In the rammed earth building, in contrast, the demand has been reduced by 86.3% in Stockholm and 73.9% in Valencia. Heat recovery ventilation and high insulation level have been identified as imperative needs in Stockholm, in contrast to Valencia. Other improvement strategies such as windows substitution, air permeability improvement, or natural ventilation for cooling have been implemented. Apart from that, better performance of the straw-bale buildings has been identified for both climates. Additionally, focusing on thermal inertia, its influence has been identified as not completely significant in terms of annual demand in the simulated climates.
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Gumgum, Sevin. "The Dual Reciprocity Boundary Element Method Solution Of Fluid Flow Problems". Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611605/index.pdf.
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In this thesis, the two-dimensional, transient, laminar flow of
viscous and incompressible fluids is solved by using the dual
reciprocity boundary element method (DRBEM). Natural convection and
mixed convection flows are also solved with the addition of energy
equation. Solutions of natural convection flow of nanofluids and
micropolar fluids in enclosures are obtained for highly large values
of Rayleigh number. The fundamental solution of Laplace equation is
used for obtaining boundary element method (BEM) matrices whereas
all the other terms in the differential equations governing the
flows are considered as nonhomogeneity. This is the main advantage
of DRBEM to tackle the nonlinearities in the equations with
considerably small computational cost. All the convective terms are
evaluated by using the DRBEM coordinate matrix which is already
computed in the formulation of nonlinear terms. The resulting
systems of initial value problems with respect to time are solved
with forward and central differences using relaxation parameters,
and the fourth-order Runge-Kutta method. The numerical stability
analysis is developed for the flow problems considered with respect
to the choice of the time step, relaxation parameters and problem
constants. The stability analysis is made through an eigenvalue
decomposition of the final coefficient matrix in the DRBEM
discretized system. It is found that the implicit central difference
time integration scheme with relaxation parameter value close to
one, and quite large time steps gives numerically stable solutions
for all flow problems solved in the thesis. One-and-two-sided
lid-driven cavity flow, natural and mixed convection flows in
cavities, natural convection flow of nanofluids and micropolar
fluids in enclosures are solved with several geometric
configurations. The solutions are visualized in terms of
streamlines, vorticity, microrotation, pressure contours, isotherms
and flow vectors to simulate the flow behaviour.
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Koller, David. "A Solution Under Pressure: Integrating Facilitative Practices into Water-Related Civil Litigations". Thesis, University of Oregon, 2017. http://hdl.handle.net/1794/22745.
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The broad scope of this research concerns the field of conflict and dispute resolution, also referred to as alternative dispute resolution (ADR). ADR practices have developed in both executive and judicial branches of government since the early 1900’s. The goal of this paper is to evaluate how ADR practitioners working in water-related civil litigation can apply facilitative practices prior, during, and after the proceeding to reduce harm, cost, and time of litigation and increase the overall satisfaction of the parties when the proceeding has been resolved. To achieve this goal, a framework is constructed and applied to a case study in Cascade Locks, Oregon. This framework is not a way to avoid a court proceeding through use of alternative dispute resolution; instead this paper seeks to add facilitative practices to a civil litigation process to make the entire process more efficient to the parties and effective in resolving the dispute.
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Reséndiz, Marino. "Photochemical decarbonylation of ketones in the solid state and in solution ; Progress towards the total synthesis of natural products". Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1790313711&sid=16&Fmt=2&clientId=48051&RQT=309&VName=PQD.
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Kelly, Sean R. "STRUCTURAL MECHANISMS OF (POLY)ANION SOLID SOLUTION IN SYNTHETIC OH-Cl BINARY APATITE AND NATURAL F-OH-Cl TERNARY APATITE". Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1480963439051542.
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Alsoy-akgun, Nagehan. "The Dual Reciprocity Boundary Element Solution Of Helmholtz-type Equations In Fluid Dynamics". Phd thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615729/index.pdf.
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In this thesis, the two-dimensional, unsteady, laminar and incompressible fluid flow problems governed by partial differential equations are solved by using dual reciprocity boundary element method (DRBEM). First, the governing equations are transformed to the inhomogeneous modified Helmholtz equations, and then the fundamental solution of modified Helmholtz equation is used for obtaining boundary element method (BEM) formulation. Thus, all the terms in the equation except the modified Helmholtz operator are considered as inhomogeneity. All the inhomogeneity terms are approximated by using suitable radial basis functions, and corresponding particular solutions are derived by using the annihilator method. Transforming time dependent partial differential equations to the form of inhomogeneous modified Helmholtz equations in DRBEM application enables us to use more information from the original governing equation. These are the main original parts of the thesis. In order to obtain modified Helmholtz equation for the time dependent partial differential equations, the time derivatives are approximated at two time levels by using forward finite difference method. This also eliminates the need of another time integration scheme, and diminishes stability problems.
Stream function-vorticity formulations are adopted in physical fluid dynamics problems in DRBEM by using constant elements. First, the procedure is applied to the lid-driven cavity flow and results are obtained for Reynolds number values up to 2000. The natural convection flow is solved for Rayleigh numbers between 10^3 to 10^6 when the energy equation is added to the Navier-Stokes equations. Then, double diffusive mixed convection flow problem defined in three different physical domains is solved by using the same procedure. Results are obtained for various values of Richardson and Reynolds numbers, and buoyancy ratios. Behind these, DRBEM is used for the solution of natural convection flow under a magnetic field by using two different radial basis functions for both vorticity transport and energy equations. The same problem is also solved with differential quadrature method using the form of Poisson type stream function and modified Helmholtz type vorticity and energy equations. DRBEM and DQM results are obtained for the values of Rayleigh and Hartmann numbers up to 10^6 and 300, respectively, and are compared in terms of accuracy and computational cost. Finally, DRBEM is used for the solution of inverse natural convection flow under a magnetic field using the results of direct problem for the missing boundary conditions.
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MELLO, Rafael Ferreira Leite de. "A solution to extractive summarization based on document type and a new measure for sentence similarity". UNIVERSIDADE FEDERAL DE PERNAMBUCO, 2015. https://repositorio.ufpe.br/handle/123456789/15257.
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The Internet is a enormous and fast growing digital repository encompassing billions of documents in a diversity of subjects, quality, reliability, etc. It is increasingly difficult to scavenge useful information from it. Thus, it is necessary to provide automatically techniques that allowing users to save time and resources. Automatic text summarization techniques may offer a way out to this problem. Text summarization (TS) aims at automatically compress one or more documents to present their main ideas in less space. TS platforms receive one or more documents as input to generate a summary. In recent years, a variety of text summarization methods has been proposed. However, due to the different document types (such as news, blogs, and scientific articles) it became difficult to create a general TS application to create expressive summaries for each type. Another related relevant problem is measuring the degree of similarity between sentences, which is used in applications, such as: text summarization, information retrieval, image retrieval, text categorization, and machine translation. Recent works report several efforts to evaluate sentence similarity by representing sentences using vectors of bag of words or a tree of the syntactic information among words. However, most of these approaches do not take in consideration the sentence meaning and the words order. This thesis proposes: (i) a new text summarization solution which identifies the document type before perform the summarization, (ii) the creation of a new sentence similarity measure based on lexical, syntactic and semantic evaluation to deal with meaning and word order problems. The previous identification of the document types allows the summarization solution to select the methods that is more suitable to each type of text. This thesis also perform a detailed assessment with the most used text summarization methods to selects which create more informative summaries for news, blogs and scientific articles contexts.The sentence similarity measure proposed is completely unsupervised and reaches results similar to humans annotator using the dataset proposed by Li et al. The proposed measure was satisfactorily applied to evaluate the similarity between summaries and to eliminate redundancy in multi-document summarization.
Atualmente a quantidade de documentos de texto aumentou consideravelmente principalmente com o grande crescimento da internet. Existem milhares de artigos de notícias, livros eletrônicos, artigos científicos, blog, etc. Com isso é necessário aplicar técnicas automáticas para extrair informações dessa grande massa de dados. Sumarização de texto pode ser usada para lidar com esse problema. Sumarização de texto (ST) cria versões comprimidas de um ou mais documentos de texto. Em outras palavras, palataformas de ST recebem um ou mais documentos como entrada e gera um sumário deles. Nos últimos anos, uma grande quantidade de técnicas de sumarização foram propostas. Contudo, dado a grande quantidade de tipos de documentos (por exemplo, notícias, blogs e artigos científicos) é difícil encontrar uma técnica seja genérica suficiente para criar sumários para todos os tipos de forma eficiente. Além disto, outro tópico bastante trabalhado na área de mineração de texto é a análise de similaridade entre sentenças. Essa similaridade pode ser usada em aplicações como: sumarização de texto, recuperação de infromação, recuperação de imagem, categorização de texto e tradução. Em geral, as técnicas propostas são baseados em vetores de palavras ou árvores sintáticas, com isso dois problemas não são abordados: o problema de significado e de ordem das palavras. Essa tese propõe: (i) Uma nova solução em sumarização de texto que identifica o tipo de documento antes de realizar a sumarização. (ii) A criação de uma nova medida de similaridade entre sentenças baseada nas análises léxica, sintática e semântica. A identificação de tipo de documento permite que a solução de sumarização selecione os melhores métodos para cada tipo de texto. Essa tese também realizar um estudo detalhado sobre os métodos de sumarização para selecinoar os que criam sumários mais informativos nos contextos de notícias blogs e artigos científicos. A medida de similaridade entre sentences é completamente não supervisionada e alcança resultados similarires dos anotadores humanos usando o dataset proposed por Li et al. A medida proposta também foi satisfatoriamente aplicada na avaliação de similaridade entre resumos e para eliminar redundância em sumarização multi-documento.
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Caritey, Jean-Philippe. "Relation entre la modification chimique de précurseurs hydrophiles d'origine naturelle et leurs propriétés en solution diluée et semi-diluée". Rouen, 1994. http://www.theses.fr/1994ROUES013.
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Nous avons déterminé l'influence de différentes modifications chimiques sur les propriétés en solution de polysaccharides d'origine végétale déjà largement utilisés dans l'industrie pétrolière, notamment pour des questions de protection de l'environnement: l'hydroxypropylguar (HPG) est un galactomannane neutre. La fixation d'une petite quantité de longues chaînes alkyles hydrophobes lui procure un caractère associatif. Nous avons mis en évidence qu'en régime dilué, l'établissement d'interactions intramoléculaires se traduit par l'adoption d'une conformation plus compacte ce qui explique la diminution de la viscosité intrinsèque. En régime semi-dilué, des interactions intermoléculaires majoritaires sont responsables d'une forte augmentation de viscosité des solutions; la formation d'un réseau de type gel est possible si la concentration en polymère est suffisante. Nous avons observé que la salinité, la température, une faible quantité de tensio-actif et un degré de substitution en groupe hydrophobe élevé, provoquent un renforcement de ces interactions. L'étude de l'effet du temps et de la réversibilité des associations met en évidence l'importance du facteur cinétique. L'ensemble des propriétés permet d'envisager l'application dans des formulations de forage. La carboxyméthylcellulose (CMC) est un éther de cellulose anionique dont les propriétés en solution peuvent être profondément modifiées par une modification chimique appropriée. La nature du substituant et le site de substitution sont les deux paramètres dont on s'est attaché à montrer l'importance. La fixation de groupes hydrophobes sur les fonctions carboxylate provoque une baisse importante de la solubilité, alors qu'un groupe hydrophile fixé sur les fonctions alcool l'améliore. Cependant, une attention particulière doit être portée lors de la réaction de modification afin d'éviter toute dégradation de la chaîne principale du polymère
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De, Pietro Júlia [UNESP]. "Fisiologia pós-colheita de rosas cortadas cv. Vega". Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/96947.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Face à carência de estudos relacionados à fisiologia pós-colheita de flores, a presente pesquisa teve como finalidade estudar a fisiologia e conservação póscolheita de flores cortadas de rosas cv. Vega, considerando os fatores associados à senescência floral e perda de vida decorativa. Os experimentos foram conduzidos em delineamento inteiramente casualizado, em esquema fatorial. Em todos os experimentos, as rosas foram mantidas em ambiente de laboratório com 20±2ºC e 67±3% UR, padronizadas em 50 cm e realizadas as seguintes avaliações (exceto para o experimento 5): perda de massa fresca, massa seca, taxa respiratória, notas de qualidade (escurecimento, turgescência e curvatura), conteúdo relativo de água, carboidratos solúveis e redutores, antocianina e coloração. Para o experimento 5 foi avaliada a quantidade de água absorvida e transpirada das rosas. No primeiro experimento, as flores foram colocadas dentro de uma câmara hermética e expostas ao 1-MCP, por um período de seis horas, nas seguintes concentrações: 1) Água destilada (controle); 2) 1-MCP 100 a ppb; 3) 1-MCP a 250 ppb; 4) 1-MCP a 500 ppb. Ao contrário do tratamento com água destilada, todas as concentrações de 1-MCP foram eficientes para retardar a senescência das flores, com destaque para a de 500 ppb que melhor manteve a qualidade, além de prolongar a vida de vaso das rosas até 19 dias. No segundo experimento, as flores permaneceram nas seguintes soluções de manutenção: 1) Água destilada (Controle); 2) 8-HQC (200 mg.L-1); 3) Sacarose (2%) + 8-HQC (200 mg.L-1); 4) Ácido Cítrico (75 mg.L-1); 5) Sacarose (2%) + Ácido Cítrico (75 mg.L-1); 6) 6- BA (60 mg.L-1); 7) Sacarose (2%) + 6-BA (60 mg.L-1). As rosas foram muito sensíveis à 6-benziladenina, associada ou não à sacarose, e perderam a qualidade aos seis dias de vida de vaso. Em contrapartida, o tratamento com 8-hidroxiquinolina...
Given the lack of studies on postharvest physiology of flowers, this research aims to study the postharvest physiology and keeping quality of Vega cut rose, were observed the factors associated with floral senescence and loss of decorative life. The experiments followed complete randomized design, in factorial arrangement. In all experiments, the roses were kept at room temperature with 20 ± 2ºC and 67±3% UR, standardized at 50 cm and it were analysis (except the fifth experiment): weight loss, dry weight, rate respiratory, quality (browning, turgidity and curvature), relative water content, soluble and reducing carbohydrates, anthocyanin, color and longevity. On the fifth experiment was to evaluation the water absorbed and transpired roses. On the first experiment, the flowers were placed inside an airtight chamber and exposed to 1-MCP for a period of six hours, in these concentrations: 1) Distilled water (control); 2) 1-MCP (100 ppb); 3) 1-MCP ( 250 ppb); 4) 1-MCP (500 ppb). Unlike treatment with distilled water, all concentrations of 1-MCP were effective in delaying the senescence of flowers, however, the concentration of 500 ppb of 1-MCP induced better maintenance of quality and extended vase life of roses to 19 days. On the second experiment, the flowers remained in these following holding solutions: 1) Distilled water (Control); 2) 8-HQC (200 mg.L-1); 3) Sucrose (2%) + 8-HQC (200 mg.L-1); 4) Citric Acid (75 mg.L-1); 5) Sucrose (2%) + Citric Acid (75 mg.L-1); 6) 6-BA (60 mg.L-1); 7) Sucrose (2%) + 6-BA (60 mg.L-1). The roses were very sensitive to 6-benzyladenine, with or without sucrose, and lost quality of six days of vase life. In contrast, treatment with 8-hydroxyquinoline has proved the most promising to maintain the quality of the flowers, for ten days. On the third experiment, the roses were treated this way: 1) Distilled water (Control), 2) STS (1 mM) ... (Complete abstract click electronic access below)
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Pires, Plínio Ferreira. "Estudo da carbonatação avançada em concretos contendo adições minerais". Universidade Federal de Goiás, 2016. http://repositorio.bc.ufg.br/tede/handle/tede/6319.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The carbonation phenomenon consists in a physicochemical process which reduces the alkalinity of concrete. Carbonation can destabilize the protective layer of the steel, leaving it susceptible to corrosion, which is one of the most significant and costly causes of deterioration in reinforced concrete. Accordingly, chemical analysis of the pore solution has been held for about 60 years, but few studies are focused on types of concrete containing mineral additions subjected to carbonation, due to the difficulty of obtaining the pore solution, given its structure densification under these conditions. Depending on the concrete composition, the natural carbonation process can take several years to present sufficient analyzable data, therefore, most of the studies on this topic use accelerated tests to simulate this phenomenon. However, even with full control of the laboratory environment, it is not possible to reproduce the randomness of the variables responsible for the degradation that occur in real situations. This study aims to evaluate the process of natural carbonation in 36 different types of concrete or analysis conditions, which cover a wide range of characteristics and properties of concrete that represent the various service situations of the structures, after about 14 years of exposure, in typical urban environment. The results are presented for types of concrete with and without mineral additions (silica fume, rice husk ash, metakaolin, fly ash and blast furnace slag); three water/binder (0.40, 0.55 and 0.70) and two curing conditions (dry-cured and moist-cured). The study was conducted by the application of simplified models of carbonation and statistical analysis on an extensive experimental database (over 2000 measurements) obtained by eight evaluations of carbonation carried at different ages, through 14 years of natural exposure prototypes of concrete beams. In addition, chemical analysis of pH, ionic strength and conductivity of the pore solution - obtained through innovative method - were conducted in both the carbonated layer and the non-carbonated layer of concrete. The results indicate that the empirically-analytical model proposed by Tuutti, has an excellent representativity of carbonated depth over time. The use of a coefficient of carbonation, from Tuutti’s model, calculated from early ages, can generate mistaken conclusions: underestimating the dry-cured concrete and overestimating the moist-cured concrete. In the overall analysis of the natural carbonation coefficients obtained by ANOVA showed that the water/binder ratio is the most significant factor, followed by curing type and, finally, the type of addition. The best performances as the carbonation are observed to the lower water/binder concretes, subjected to wet cure. Under the method used to obtain the pore solution, it was possible to compare the difference between the chemical properties of non-carbonated and carbonated layers of each type of concrete analyzed.
O fenômeno da carbonatação consiste em um processo físico-químico que leva à redução de alcalinidade do concreto. Isto pode desestabilizar a camada protetora do aço, deixando-o passível de corrosão, que é uma das mais importantes e onerosas causas de deterioração do concreto armado. Nesse sentido, a análise química da solução do poro tem sido realizada há cerca de 60 anos, contudo raros trabalhos focam em concretos submetidos à carbonatação contendo adições minerais, dada a dificuldade de se obter a solução devido à densificação na estrutura porosa nessas condições. Dependendo da composição do concreto, o processo de carbonatação natural pode levar vários anos para apresentar dados passíveis de análise, diante disso, a maioria dos estudos nesse tema utilizam ensaios acelerados para simular tal fenômeno, contudo, mesmo com todo controle do ambiente de laboratório, não se pode reproduzir a aleatoriedade das variáveis que ocorre em situações reais de degradação. Este trabalho tem como objetivo avaliar o processo de carbonatação natural em 36 diferentes concretos ou condições de análise, os quais cobrem uma ampla faixa de características e propriedades dos concretos, representando as mais diversas situações de serviço para as estruturas, após cerca de 14 anos de exposição, em ambiente típico urbano. São, portanto, apresentados resultados de concretos sem e com adições minerais (sílica ativa, cinza de casca de arroz, metacaulim, cinza volante e escória de alto-forno); três relações água/ligante (0,40; 0,55 e 0,70) e duas condições de cura (seca e úmida). O estudo se deu por meio de aplicações de modelos simplificados de carbonatação e análises estatísticas em um extenso banco de dados experimentais (mais de 2000 medidas) obtido por oito avaliações da frente de carbonatação realizadas em diferentes idades, durante 14 anos de exposição natural de protótipos de vigas de concreto. Foram realizadas também análises químicas de pH, força iônica e condutividade da solução do poro, obtida através de método inovador, tanto da camada carbonatada quanto da camada não carbonatada dos concretos. Os resultados indicam que o modelo empírico-analítico, proposto por Tuutti, possui excelente representatividade da profundidade carbonatada ao longo do tempo. A utilização de um coeficiente de carbonatação, do modelo de Tuutti, calculado a partir de idades iniciais pode gerar conclusões equivocadas: subestimando os concretos sem cura e superestimando os de cura úmida. A análise global dos coeficientes de carbonatação, obtidos pela ANOVA, demonstrou que a relação água/ligante é o fator mais significativo, seguido do tipo de cura e, por último, o tipo de adição. Os melhores desempenhos quanto à carbonatação são observados para os concretos de menor relação água/ligante, submetidos à cura úmida. De acordo com o método empregado para obtenção da solução do poro, foi possível comparar a diferença entre as propriedades químicas da camada não carbonatada e a carbonatada, para toda a família de concretos analisada.
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Blachot, Jean-François. "Étude des propriétés rhéologiques des solutions cellulose/monohydrate de N-oxyde de N-méthylmorpholine (NMMO) : filage de cellulose extraite de paille de blé : structure et fibrillation des fils obtenus". Université Joseph Fourier (Grenoble ; 1971-2015), 1995. http://www.theses.fr/1995GRE10189.
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Une etude originale des proprietes rheologiques de solutions de cellulose dissoute dans du monohydrate de n-oxyde de n-methylmorpholine (nmmo) nous a permis de determiner l'influence de la concentration et de la masse molaire de la cellulose sur les valeurs de la viscosite newtonienne et du temps d'ecoulement qui evoluent respectivement comme c#4#,#6m#5 et c#2#,#7m#5. D'autre part, des mesures effectuees en spectrometrie mecanique a differentes temperatures ont permis d'elaborer une courbe maitresse decrivant le comportement de ces solutions depuis l'etat visqueux jusqu'a l'etat vitreux. Nous avons aussi file par voie humide des solutions contenant 10% de pates cellulosiques, plus ou moins raffinees, qui ont ete extraites de la paille de ble grace a un traitement par explosion a la vapeur. Les fils d'un diametre de 13 micrometres presentent une structure fibrillaire tres orientee pouvant conduire a des delaminations de surface. Ce phenomene designe sous le nom de fibrillation est fonction de la nature et de la concentration en lignines. L'analyse de la structure, et plus particulierement, de la dechirure longitudinale des fils montre que la fibrillation est reliee a la cohesion laterale des fibrilles. Par ailleurs, dans une application de type materiaux composites, cette fibrillation augmente le renfort produit par les fibres dans les matrices de polymeres
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Cai, Zhemin. "A High-order Discontinuous Galerkin Method for Simulating Incompressible Fluid-Thermal-Structural Problems". Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/20961.
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The use of discontinuous Galerkin (DG) methods to solve fluid thermal structure interaction problems in numerical modelling is known to offer several advantages. In particular, DG methods provide the flexibility of using different approximations in different elements, which makes the methods ideal for hp-adaptivity. The first objective of this thesis is to present a framework for the computation of fluid thermal structure interaction problems within both the single and multi-solid domain using DG methods on unstructured grids. The full solver consists of four main components: the incompressible fluid solver, the conjugate heat transfer solver, the linear elastic solver and the fluid to structure interaction solver. Based on an earlier developed DG solver for the incompressible Navier-Stokes equation, the fluid advection-diffusion equation, the Boussinesq term, the solid heat equation and the linear elastic equation are introduced using an explicit DG formulation. A Dirichlet-Neumann partitioning strategy has been implemented to achieve the data exchange process via the numerical flux of interface quadrature points in the fluid-solid interface. Formal h and p convergence studies employing the method of manufactured solutions demonstrate that the expected order of accuracy is achieved. Computational effort is documented in detail demonstrating precisely that for all cases the highest order accurate algorithm has several magnitudes lower error than lower-order schemes for a given computational effort. Secondly, this thesis has proposed a detailed compact thermoelectric cooler (TEC) modelling method based on an existing black box like compact TEC model. Close comparisons validate that both the detailed and the black box like compact model are accurate enough to simulate the conduction only case. When air convection is required to carry out a system-level thermal management optimization, the detailed compact modelling method is more reliable.
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Salov, Aleksandar. "Towards automated learning from software development issues : Analyzing open source project repositories using natural language processing and machine learning techniques". Thesis, Linnéuniversitetet, Institutionen för medieteknik (ME), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-66834.
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This thesis presents an in-depth investigation on the subject of how natural language processing and machine learning techniques can be utilized in order to perform a comprehensive analysis of programming issues found in different open source project repositories hosted on GitHub. The research is focused on examining issues gathered from a number of JavaScript repositories based on their user generated textual description. The primary goal of the study is to explore how natural language processing and machine learning methods can facilitate the process of identifying and categorizing distinct issue types. Furthermore, the research goes one step further and investigates how these same techniques can support users in searching for potential solutions to these issues. For this purpose, an initial proof-of-concept implementation is developed, which collects over 30 000 JavaScript issues from over 100 GitHub repositories. Then, the system extracts the titles of the issues, cleans and processes the data, before supplying it to an unsupervised clustering model which tries to uncover any discernible similarities and patterns within the examined dataset. What is more, the main system is supplemented by a dedicated web application prototype, which enables users to utilize the underlying machine learning model in order to find solutions to their programming related issues. Furthermore, the developed implementation is meticulously evaluated through a number of measures. First of all, the trained clustering model is assessed by two independent groups of external reviewers - one group of fellow researchers and another group of practitioners in the software industry, so as to determine whether the resulting categories contain distinct types of issues. Moreover, in order to find out if the system can facilitate the search for issue solutions, the web application prototype is tested in a series of user sessions with participants who are not only representative of the main target group which can benefit most from such a system, but who also have a mixture of both practical and theoretical backgrounds. The results of this research demonstrate that the proposed solution can effectively categorize issues according to their type, solely based on the user generated free-text title. This provides strong evidence that natural language processing and machine learning techniques can be utilized for analyzing issues and automating the overall learning process. However, the study was unable to conclusively determine whether these same methods can aid the search for issue solutions. Nevertheless, the thesis provides a detailed account of how this problem was addressed and can therefore serve as the basis for future research.
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De, Pietro Júlia. "Fisiologia pós-colheita de rosas cortadas cv. Vega /". Jaboticabal : [s.n.], 2009. http://hdl.handle.net/11449/96947.
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Resumo: Face à carência de estudos relacionados à fisiologia pós-colheita de flores, a presente pesquisa teve como finalidade estudar a fisiologia e conservação póscolheita de flores cortadas de rosas cv. Vega, considerando os fatores associados à senescência floral e perda de vida decorativa. Os experimentos foram conduzidos em delineamento inteiramente casualizado, em esquema fatorial. Em todos os experimentos, as rosas foram mantidas em ambiente de laboratório com 20±2ºC e 67±3% UR, padronizadas em 50 cm e realizadas as seguintes avaliações (exceto para o experimento 5): perda de massa fresca, massa seca, taxa respiratória, notas de qualidade (escurecimento, turgescência e curvatura), conteúdo relativo de água, carboidratos solúveis e redutores, antocianina e coloração. Para o experimento 5 foi avaliada a quantidade de água absorvida e transpirada das rosas. No primeiro experimento, as flores foram colocadas dentro de uma câmara hermética e expostas ao 1-MCP, por um período de seis horas, nas seguintes concentrações: 1) Água destilada (controle); 2) 1-MCP 100 a ppb; 3) 1-MCP a 250 ppb; 4) 1-MCP a 500 ppb. Ao contrário do tratamento com água destilada, todas as concentrações de 1-MCP foram eficientes para retardar a senescência das flores, com destaque para a de 500 ppb que melhor manteve a qualidade, além de prolongar a vida de vaso das rosas até 19 dias. No segundo experimento, as flores permaneceram nas seguintes soluções de manutenção: 1) Água destilada (Controle); 2) 8-HQC (200 mg.L-1); 3) Sacarose (2%) + 8-HQC (200 mg.L-1); 4) Ácido Cítrico (75 mg.L-1); 5) Sacarose (2%) + Ácido Cítrico (75 mg.L-1); 6) 6- BA (60 mg.L-1); 7) Sacarose (2%) + 6-BA (60 mg.L-1). As rosas foram muito sensíveis à 6-benziladenina, associada ou não à sacarose, e perderam a qualidade aos seis dias de vida de vaso. Em contrapartida, o tratamento com 8-hidroxiquinolina ... (Resumo completo, clicar acesso eletrônico abaixo)Abstract: Given the lack of studies on postharvest physiology of flowers, this research aims to study the postharvest physiology and keeping quality of Vega cut rose, were observed the factors associated with floral senescence and loss of decorative life. The experiments followed complete randomized design, in factorial arrangement. In all experiments, the roses were kept at room temperature with 20 ± 2ºC and 67±3% UR, standardized at 50 cm and it were analysis (except the fifth experiment): weight loss, dry weight, rate respiratory, quality (browning, turgidity and curvature), relative water content, soluble and reducing carbohydrates, anthocyanin, color and longevity. On the fifth experiment was to evaluation the water absorbed and transpired roses. On the first experiment, the flowers were placed inside an airtight chamber and exposed to 1-MCP for a period of six hours, in these concentrations: 1) Distilled water (control); 2) 1-MCP (100 ppb); 3) 1-MCP ( 250 ppb); 4) 1-MCP (500 ppb). Unlike treatment with distilled water, all concentrations of 1-MCP were effective in delaying the senescence of flowers, however, the concentration of 500 ppb of 1-MCP induced better maintenance of quality and extended vase life of roses to 19 days. On the second experiment, the flowers remained in these following holding solutions: 1) Distilled water (Control); 2) 8-HQC (200 mg.L-1); 3) Sucrose (2%) + 8-HQC (200 mg.L-1); 4) Citric Acid (75 mg.L-1); 5) Sucrose (2%) + Citric Acid (75 mg.L-1); 6) 6-BA (60 mg.L-1); 7) Sucrose (2%) + 6-BA (60 mg.L-1). The roses were very sensitive to 6-benzyladenine, with or without sucrose, and lost quality of six days of vase life. In contrast, treatment with 8-hydroxyquinoline has proved the most promising to maintain the quality of the flowers, for ten days. On the third experiment, the roses were treated this way: 1) Distilled water (Control), 2) STS (1 mM) ... (Complete abstract click electronic access below)
Orientador: Ben-Hur Mattiuz
Coorientador: Teresinha de Jesus Deléo Rodrigues
Coorientador: Claudia Fabrino Machado Mattiuz
Banca: Kathia Fernandes Lopes Pivetta
Banca: Regina Maria Monteiro de Castilho
Mestre
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Kalyva, Maria. "Fate of pharmaceuticals in the environment - A review-". Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-132995.
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The occurrence of pharmaceuticals in environment originating from human consumption has received increased scientific attention during the last decades due to concerns regarding their combined environmental effects in aquatic and terrestrial environments, in flora and biota and by extent in human health. In this review, I summarized the existing knowledge on the entire life cycle of pharmaceutical substances, from their exposure (sources) and fate to their effects on the natural environment. Since the negative effects of several drugs along with the environmental damage they entail are now known, it can be suggested that pharmaceutical companies make greener pharmaceutical products to reduce these effects to the terrestrial and aquatic environment. The present review could provide suggestions to improve the pharmaceutical environmental management globally, such as methodologies for monitoring systems, that need to be put in place for consistent data collection. Another area of research that is important is the release of pharmaceutical compounds in manufacturing plants as well as from landfill effluent. Finally, one more area with need for further research is green chemistry which could reduce or even eliminate the potential hazards of pharmaceutical compounds that enter the environment, irrespective to the source of entry.
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Morris, Graham Peter. "Parameter recovery in AC solution-phase voltammetry and a consideration of some issues arising when applied to surface-confined reactions". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:1b1d40f3-ef1a-4f64-b500-17ce34630c43.
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A major problem in the quantitative analysis of AC voltammetric data has been the variance in results between laboratories, often resulting from a reliance on "heuristic" methods of parameter estimation that are strongly dependent on the choices of the operator. In this thesis, an automatic method for parameter estimation will be tested in the context of experiments involving electron-transfer processes in solution-phase. It will be shown that this automatic method produces parameter estimates consistent with those from other methods and the literature in the case of the ferri-/ferrocyanide couple, and is able to explain inconsistency in published values of the rate parameter for the ferrocene/ferrocenium couple. When a coupled homogeneous reaction is considered in a theoretical study, parameter recovery is achieved with a higher degree of accuracy when simulated data resulting from a high frequency AC voltammetry waveform are used. When surface-confined reactions are considered, heterogeneity in the rate constant and formal potential make parameter estimation more challenging. In the final study, a method for incorporating these "dispersion" effects into voltammetric simulations is presented, and for the first time, a quantitive theoretical study of the impact of dispersion on measured current is undertaken.
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Bose, Sweta. "Dissolution Kinetics of Sulfate Minerals: Linking Environmental Significance of Mineral-Water Interface Reactions to the Retention of Aqueous CrO42- in Natural Waters". Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1207285064.
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Fenger, Julie-Anne. "Les anthocyanes acylées en tant que colorants naturels : réactivité en solution aqueuse, complexation métallique et stabilisation pour des applications alimentaires The chemical reactivity of anthocyanins and its consequences in food science and nutrition The influence of acylation and metal binding on the thermal stability of red cabbage anthocyanins The fate of acylated anthocyanins in neutral solution". Thesis, Avignon, 2020. http://www.theses.fr/2020AVIG0278.
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Les anthocyanes sont des pigments d’origine végétale exprimant des couleurs vives allant du rouge au bleu. Ce sont donc de bons candidats pour remplacer les colorants alimentaires artificiels. Cependant, leur faible stabilité est un frein à ces applications, tout particulièrement en milieu neutre requis pour l’expression de la couleur bleue. Une perspective prometteuse est le recours aux anthocyanes acylées par les acides phydroxycinnamiques, car ces pigments développent des mécanismes protecteurs de la couleur (copigmentation intramoléculaire, auto-association) basés sur de fortes interactions d’empilement entre le chromophore et les résidus acyl. Ce travail étudie donc les transformations structurales d’anthocyanes acylées (transferts de proton, addition d’eau), leur affinité pour les ions métalliques et leur stabilité au cours d’un traitement thermique. Dans ce but, des études cinétiques et thermodynamiques par spectroscopie UV-visible sont combinées à l’identification de produits de dégradation par UPLC-DAD/MS. L’impact des groupements acyl (nombre, position, type) a été étudié grâce à une gamme de pigments isolés du chou rouge et de la patate douce pourpre. Pour les premiers, les groupements acyl sur le sucre externe du groupement sophorose confèrent a) une protection optimale contre les attaques par H2O, H2O2 and SO32-, b) une plus grande affinité pour les ions métalliques, c) une plus grande stabilité thermique (pour les pigments et leurs complexes). En revanche, l’acide caféique, qu’il soit libre ou bien sous forme de résidu acyl (cas des anthocyanes de la patate douce violette), accélère la dégradation des anthocyanes, bien qu’il stabilise la couleur. Un traitement thermique modéré à pH 7 a converti les anthocyanes du chou rouge en acylsophoroses, phloroglucinaldéhyde-2-O-glucoside, acide protocatéchuique, dérivés de la 3,5,7-trihydroxycoumarine et de l’acide 2,4,6-trihydroxyphenylacétique. Un phénomène de migration intramoléculaire de résidus acyl a également été mis en évidence. La base anionique, une forme colorée majeure à pH 7, apparaît comme la plus vulnérable à l’autoxydation. Le peroxyde d’hydrogène ainsi formé est également impliqué dans la dégradation des anthocyanes. Globalement, nos résultats montrent que la forte association des anthocyanes acylées avec les ions du fer et de l’aluminium, voire l’ajout d’antioxydants naturels (par ex., la Nacétylcystéine), constituent des voies d’avenir pour le développement de colorants bleus naturels stablesAnthocyanins are ubiquitous plant pigments that exhibit bright colors from red to blue. Thus, they are good candidates to replace the synthetic food colors. However, the low stability of anthocyanin colors is a real hurdle to their industrial applications, especially under near neutral conditions required to express the blue color. A promising perspective is to resort to anthocyanins acylated by p-hydroxycinnamic acids, as these pigments develop colorstabilizing mechanisms (intramolecular copigmentation, self-association) based on strong stacking interactions between the anthocyanidin chromophore and the acyl residues. Therefore, this work investigates the structural transformations of acylated anthocyanins (proton transfer, water addition), their affinity to metal ions and their resistance to thermal degradation in the presence or absence of added metal ions. To that purpose, kinetic and thermodynamic studies by UV-visible spectroscopy are combined with the identification of degradation products by UPLC-DAD/MS. The impact of the acyl residues (number, location, type) was deciphered from a series of isolated pigments from red cabbage and purple sweet potato. With the former, the acyl residue bound to the external glucose of the sophorose moiety provides a) optimal protection against attacks by H2O, H2O2 and sulfite, b) improved affinity for metal ions, c) enhanced resistance against thermal degradation (for anthocyanins and their metal complexes). By contrast, caffeic acid, whether free or as an acyl residue (in purple sweet potato), accelerates the degradation of anthocyanins in spite of stabilizing the color. Under moderate heating at pH 7, red cabbage anthocyanins were degraded into acylsophoroses, phloroglucinaldehyde-2-O-glucoside, protocatechuic acid, 3,5,7trihydroxycoumarin derivatives, and 2,4,6-trihydroxyphenylacetic acid derivatives. Intramolecular acyl migration was also evidenced. The anionic base, a major colored form at pH 7, appears most vulnerable to autoxidation. The hydrogen peroxide thus produced is further involved in anthocyanin degradation. Overall, the tight binding of acylated anthocyanins to iron and aluminum ions and possibly the addition of natural antioxidants (e.g., N-acetylcysteine) are promising perspectives for the development of stable natural blue colors
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Ji, Yuefei. "Photochemical and photocatalytic degradation of pharmaceutical and personal care products (PPCPS) in aqueous solution : a case study of atenolol and 2-phenylbenzimidazole-5-sulfonic acid". Phd thesis, Université Claude Bernard - Lyon I, 2014. http://tel.archives-ouvertes.fr/tel-01058226.
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In this thesis, the photochemical and photocatalytic degradation of atenolol (ATL) and 2-phenylbenzimidazole-5-sulfonic acid (PBSA) have been investigated in aqueous solutions. Our results show that direct photolysis of ATL is weak and the indirect photolysis, e.g., induced by photosensitizers such as nitrate, may contributed to its major loss process in natural sunlit waters. In the case of PBSA, direct photolysis is found to be important while the indirect photolysis may play a less important role in its elimination in natural surface waters. The photolytic reactions (either direct or indirect) generally obey pseudo-first-order kinetics and can be influence by the solution pH, the co-existence of other water constituents such as dissolved organic matter (DOM) and bicarbonate ion (HCO3-). The photolytic degradation lead to a variety of intermediates and products. However, the reduction in TOC of the photolysis is usually found to be insignificant compared to the disappearance of the mother compound. Nevertheless, the observed decrease in toxicity toward fresh water species D. magna in nitrate-induced photodegradation of ATL implies indirect photolysis of ATL is possibly an important way to reduce the toxicity to ecosystem. It should be noted that direct and indirect photodegradation may process through different pathways and mechanism as observed in the photolysis of PBSA in this work. Photocatalytic oxidation of ATL and PBSA were carried out in illuminated aqueous TiO2 suspensions. Photocatalytic reactions normally follow pseudo-first-order kinetics. The kinetics are strongly affected by the photocatalyst type, the photocatalyst dosage, the solution pH value and the substrate concentration. Hydroxyl radical (HO*) was determined to be the major reactive specie responsible for the remarkable degradation of mother compounds. The degradation efficiency is largely influenced by the water matrices as well as the formation and transformation of intermediates. It should be noted that Degussa P25 showed the highest photocatalytic activity for oxidizing ATL and PBSA compared to pure anatase or rutile catalyst such as Hombikat UV 100, Millennium PC 500 and Aldrich rutile, which is in line with previous reports. The photocatalytic degradation of mother compounds results in the formation of various intermediates (e.g., formic, oxalic, malonic acid) and inorganic ions (e.g., NH4+, NO3-, SO42-). TOC decreases much more slowly as compared to the disappearance of the mother compounds, however, complete mineralization could be obtained with longer irradiation time
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Parks, David William. "Sub-sea gas processing". Thesis, Curtin University, 2011. http://hdl.handle.net/20.500.11937/2588.
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To meet the demands of deeper and more remote reservoirs, subsea processing has been poised as one of the most potentially promising technology developments in the offshore development.Natural Gas usually contains significant quantities of water vapour, which must be removed for gas processing and transmission. A pipeline transporting natural gas at a pressure of 10 Mega Pascals at equilibrium with seawater at 4 C must have water content lower than around 144 parts per million (by volume) to ensure water will not condense within the pipeline. Failure to sufficiently reduce the water content can lead to condensation of liquid water and the formation and accumulation of gas hydrates into pipe blocking plugs. This is particularly important for subsea pipelines with the high pressure and low temperatures conditions that exposes the gas to hydrate formation conditions.This research investigates a novel dehydration solution that is applicable for subsea installation. The technique is based on technology that was trialled in an above ground implementation by Cool Energy with significant system modifications to make it applicable to a subsea environment. The ultimate objective of this research is to develop a sea bed dehydration solution that will reduce the water content of the gas to pipeline quality standard.The solution utilises the concepts of gas cooling through expansion and the controlled formation and management of gas hydrates to reduce the water content of a saturated gas stream to levels suitable for gas transport in subsea pipelines. A pilot plant was implemented to test the solution design at pressures up to 10 Mega Pascals and flow rates of 35 standard cubic meters per hour. The experiments successfully demonstrated gas dehydration to below -40 degrees C, performance that meets the pipeline water specification requirements for subsea transportation of natural gas.This thesis presents the current status of implemented subsea technology, reviews current dehydration technologies and discusses their applicability to subsea implementation. It describes the iterative dehydration process development and presents the achieved dehydration results. A production scenario is defined and a modelled solution presented together with novel approaches in management of the system.
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Capacci, Christian. "Resistenza idraulica del rivestimento arginale vegetato: sperimentazione in canaletta e velocimetria doppler". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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Le tecniche di protezione “a verde” sono ampiamente utilizzate al fine di mitigare il fenomeno dell’erosione superficiale delle sponde fluviali o lungo le scarpate dei pendii, in quanto di facile installazione ed eco-compatibili. Nello studio affrontato si è realizzata una sperimentazione in canaletta idraulica, con lo scopo di stabilire quali sono le caratteristiche che un buon rivestimento vegetativo deve avere per poter garantire un’opportuna protezione all’erosione nel caso di suolo a contatto con l’acqua.
Le prove sperimentali sono state condotte presso il laboratorio di idraulica LIDR del DICAM ed hanno interessato tre potenziali condizioni in cui la sponda si può trovare: terreno privo di vegetazione e terreno con due tipi di piante caratterizzate da tempi di crescita ed impianto radicale diverso, adoperate abitualmente nelle operazioni di inerbimento fluviale.
I dati sperimentali sono stati raccolti impiegando la tecnologia ad ultrasuoni (UVP), il cui utilizzo in ambiente idraulico sta riscuotendo un sempre maggiore interesse, grazie alla precisione ed alla flessibilità che tale strumentazione è in grado di offrire.
Le risultanze emerse, seppur preliminari, evidenziano il ruolo protettivo offerto dalla copertura vegetale che appare in grado di ridurre fortemente le tensioni tangenziali esercitate dalla corrente in prossimità del suolo.
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Natali, Andrea. "Double Dyke System - Natural engineering solutions". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21243/.
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According to various studies, the effects of climate change will be a danger to ecosystems and the population, especially in coastal areas, increasing the risk of floods. Authorities are taking action to prevent future disasters using traditional engineering solutions. These solutions can have high environmental and economic costs, fixing the coastline, increasing the salinization of aquifers, and can be subject to failure mechanisms.
For this reason, studies were made to use natural engineering solutions for coastal protection, instead of traditional solutions, to achieve the UN SDGs. Coastal ecosystems have the natural ability to repair and restore themselves, increasing soil elevation, and attenuating waves. One of these solutions is the Double Dyke System, consisting of creating a salt marsh between the first dyke and a second inland. The goal is to protect the coasts and to restore ecosystems.
The purpose of this study is to compare the costs of natural engineering solutions with traditional ones. It is assumed that these solutions may be more effective and less expensive in the long run. For this evaluation, a suitability analysis of the polders in the Dutch Zeeland region to assess the costs and benefits under different SLR scenarios was made. A saline intrusion model was also created to analyze the effects of a salt marsh on the aquifers. From the analyzes conducted, the implementation of the DDS turns out to be the cheapest coastal defense system in all SLR scenarios. The presence of a salt marsh could also have a positive impact on the prevention of saline intrusion in the various scenarios considered.
The DDS could have a positive economic and environmental impact in the long term, reducing the investment costs for coastal defense and bringing important benefits for the protection of man and nature.
Despite the results, more studies are needed on the efficiency of this defense system and on the economic evaluation of non-marketable ecosystem services.
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Corrales, Juliana. "Modeling a Phosphorus Credit Trading Program in the Lake Okeechobee Watershed". FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2294.
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Lake Okeechobee is the largest lake in the southeastern United States and is a central component of the hydrology and environment of the Everglades ecosystem in South Florida. The natural state of the lake has been degraded as wetlands and natural habitats in the Lake Okeechobee watershed have been replaced with farms, urban areas, and dairy operations. Excessive phosphorus loadings from these diverse sources have been identified as the leading causes of the lake’s impairment. For more than four decades, many resources have been allocated to regional and local restoration efforts to reduce phosphorus loadings into the lake. However, phosphorus loadings have not decreased and the recovery of the lake could take more time, particularly with today’s limited local budgets.
Market-based instruments, such as water quality trading programs, have emerged over the past decades to cost-effectively achieve water quality objectives in impaired watersheds. The main objective of this dissertation was to assess the environmental and economic benefits of implementing a phosphorus trading program in Lake Okeechobee watershed, compared to a conventional command-and-control approach. A comprehensive literature overview of nationally and internationally implemented trading programs was conducted to highlight advantages and challenges of these programs towards achieving water quality goals, and to outline the essential elements of a successful program. Furthermore, a modeling framework, integrating a hydrologic-water quality model with an economic model, was developed to assess the potential cost savings that trading might offer over a command-and-control approach. The modeling framework was applied in three priority basins of the Lake Okeechobee watershed. In each case, while developing trading scenarios to achieve phosphorus load reduction targets, the trading program was less expensive than the conventional command-and-control approach.
This research provided the foundation for stakeholders to better understand whether water quality trading has the potential to work in the Lake Okeechobee watershed and to facilitate the development of a pilot program. In addition, it offered some insights on the potential economic opportunities that pollution sources would have by participating in the trading program. The modeling framework developed in this dissertation could facilitate the assessment of future water quality trading programs in other watersheds.
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Macken, Stephen. "Integrated Optical Solutions for Ubiquitous Sensing". Doctoral thesis, Linköpings universitet, Tillämpad Fysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-63709.
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Ubiquitous chemical sensing aims at exploiting consumer electronic devices as temporary chemical sensing platforms. These devices are a highly disseminated infrastructure, not presently being exploited for chemical sensing purposes. The goal of the ubiquitous chemical sensing field is to create the methodologies and adapted devices to profit from this unexploited resource. DVD drives, flat bed scanners and computer screens used in combination with web cameras, and mobile phones have been demonstrated as measuring platforms, during the past 10 years. In particular the combination of computer screens with web cameras, a technique called the computer screen photo-assisted technique (CSPT), is the most versatile approach to support multiple types of optical detection phenomena, and together with mobile phones are the most ubiquitous type of platforms. The versatility of CSPT comes from the ease with which one can configure a spectrally controlled, 2D micro-positioned, linearly polarized, wide angle and internally modulated illumination with a programmable screen, just by controlling the displayed contents. Concurrently, the imaging devices in CSPT enable one to capture arbitrary assay layouts, the evaluation of which can then be numerically customized. The full exploitation of the CSPT platform requires optically adapted sensing interfaces and specialized methods, in order to increase sensitivity and make use of all available information, for a thorough and complete chemical sensing analysis. In this thesis I have explored the foundations of CSPT sensing on integrated devices, developing methods and sensing’s interfaces that provide enhanced optical detection customized to the CSPT platform.
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Fahs, Amin. "Modeling of naturel convection in porous media : development of semi-analytical and spectral numerical solutions of heat transfer problem in special domains". Thesis, Strasbourg, 2021. https://publication-theses.unistra.fr/restreint/theses_doctorat/2021/Fahs_Amin_2021_ED269.pdf.
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Le problème de la cavité poreuse carrée est largement utilisé comme cas de référence courant pour les problèmes de Convection Naturelle (CN) en milieux poreux. Il peut être utilisé pour plusieurs applications numériques, théoriques et pratiques. Par ailleurs, toutes les solutions de haute précision existantes dans la littérature scientifique sont développées dans des conditions de régime permanent. Cependant, il est bien connu que les processus de CN dans les milieux poreux se produisent naturellement dans un régime dépendant du temps, car les conditions aux limites peuvent être variables dans le temps. Pour surmonter cette difficulté, la solution en régime permanent est souvent simulée comme une solution transitoire qui évolue jusqu'à atteindre l'état d'équilibre. Ces régimes dépendant du temps sont très efficaces pour détecter les effets des variations de paramètres sur le processus physique de CN, en particulier pour les sujets d'intérêt de cette thèse: la variation du niveau d'inclinaison du domaine et la prise en compte des variations de température de la paroi chaude dans le temps. À cet effet, trois objectifs sont identifiés dans cette thèse: 1. Développer une solution de convection naturelle en fonction du temps dans des milieux poreux en utilisant le Modèle Darcy en deux modes: transitoire et instable. 2. Étudier le comportement en fonction du temps de la convection naturelle dans des milieux poreux ayant le niveau d'inclinaison du domaine comme paramètre variable dans deux modes: transitoire et instable. 3. Développer une solution de convection naturelle en fonction du temps dans des milieux poreux en utilisant le Modèle Darcy-Lapwood-Brinkman en deux modes: transitoire et instable. Pour ce faire, du fait de la grande précision dans les domaines simplement connectés, une méthode spectrale de résidus pondérés de type Galerkin est choisie pour développer une solution au problème de CN dans une cavité carrée poreuse. L’application de la procédure de Fourier-Galerkin (FG), deux configurations traitant des régimes instables sont considérées où chaque solution est dérivée pour une large gamme des nombres de Rayleigh (Ra) avec d'autres conditions spéciales. Ce travail de thèse est subdivisé en cinq chapitres. Dans le premier chapitre, nous avons présenté un aperçu physique du processus de convection naturelle en milieux poreux. Dans le deuxième chapitre, le développement mathématique des équations, la méthode de résolution et la procédure de résolution sont décrits en détails. Dans le chapitre trois, la première étude de cas de cette thèse, la solution dépendante du temps de la convection naturelle dans une cavité carrée remplie de milieux poreux saturé utilisant le modèle de Darcy est développé. Dans le chapitre quatre, le problème de variation temporelle de Darcy-Lapwood- Brinkman de CN dans une enceinte poreuse saturée carrée est étudié. Dans le chapitre cinq, les solutions dépendant du temps sont développées pour le problème de convection naturelle utilisant la loi de Darcy dans une cavité poreuse inclinée et considéré comme une étude complète sur les effets de l'inclinaison du domaine sur le processus physique du problème de convection libre. Pour tous les cas, les régimes transitoires et instables sont considérésThe problem of the porous square cavity is extensively used as a common benchmark case for Natural convection (NC) problem in porous media. It can be used for several numerical, theoretical, and practical purposes. All the existing high accurate solutions are developed under steady-state conditions. However, it is well known that the processes of NC in porous media occurs naturally in a time-dependent procedure, as boundary conditions can be variable in time. Also, the convergence of the steady-state solution is known to be difficult. To overcome this difficulty, the steady-state solution is often simulated as a transient solution that evolves until reaching the steady-state condition. These time-dependent modes are very efficient to detect the effects of the parameter variations on the physical process of NC, especially for the subject of interest in this thesis: the domain inclination level and hot wall temperature variation in time. For this purpose, three goals are identified in this Thesis: 1. Developing a time-dependent solution of natural convection in porous media using the Darcy model in two modes: Transient and unsteady. 2. Investigating the time-dependent behavior of natural convection in porous media having the domain inclination level as a variable parameter in two modes: Transient and unsteady. 3. Developing a time-dependent solution of natural convection in porous media using the Darcy-Lapwood-Brinkman model in two modes: Transient and unsteady. To do so, according to the high accuracy in the simply connected domains, one of the Galerkin spectral weighted residual method is chosen to develop a space-time dependent solution for NC problem in a square porous cavity. Applying the Fourier-Galerkin (FG) procedure, two configurations dealing with transient and unsteady regimes are considered where each solution is derived for a wide range of Rayleigh numbers with other special conditions. This work of thesis is explained in details as five chapters.The NC physical process with the time-dependent variations is described in the transient mode to reach the steady-state solution and for the unsteady mode during a one period using periodic sinusoidal boundary conditions on the cavity hot wall. Finally, the work of this thesis is described in details in five chapters; while the sixth and last chapter is devoted to the summary and conclusion.The results in this thesis work provide a set of high-accurate data that are published in three papers to be used for testing numerical codes of heat transfer in time-dependent configurations
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Johansson, Maria. "Natural Light, Space and Perception". Thesis, KTH, Arkitektur, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280168.
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This is a research-based project investigating the relation between natural light, space and perception. It is in the format of a book with eight parts based on the observation and analysis of physical models. The spaces created in this book are divided in three parts, general daylight solutions, perceptual light-spaces and purposeful light-spaces. The first part consists of 19 spaces transferred from drawings found in Sunlighting as Formiver for Architecture by William M.C. Lam. The second part contains ten spaces based on perception and in the third part the focus in of function, which is generally divided into more general purposes of 13 models. The analysis I am using is a combination Light-zone(s) described by Merete Madsens and the Visual Terms and Seven Basic Terms by Anders Liljefors, which is a way to analyse perception. Following is an analysis of possible functions and daylight variability, which are then concluded. The spaces and findings are compared and summarised in order to find general strategies for the use of daylight in architecture. This book is meant to be used as a learning tool, a handbook and/or a basis for further investigation of the relation between natural light, space and perception.
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Rae, Ian Black. "Natural biosorbents for the removal of metals from aqueous solutions". Thesis, Open University, 2008. https://pure.uhi.ac.uk/portal/en/studentthesis/natural-biosorbents-for-the-removal-of-metals-from-aqueous-solutions(02780c75-a23e-41e9-aaae-071f211efafd).html.
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The removal of metals from potable and wastewater to regulatory standards presents unique challenges. Conventional treatments, chemical precipitation, adsorption by activated carbon, ion-exchange, electro-chemical and reverse osmosis can be expensive or ineffective at low concentrations. Recent research has shown that biosorption by low cost biomass can be an effective alternative. Biosorption is the passive (non-metabolic) uptake and concentration of metals by non-viable biological materials. In this work, natural materials and shellfish processing wastes were physiochemically characterised to identify products with suitable characteristics to perform as biosorbents. Brown seaweed (FllCliS vesiculosus), Douglas fir wood bark (Pselldolsllga menziesil), peat and carapace from the edible crab (Cancer pagurus) were assess~d for Cu(II) removal as a function of time and concentration. Mechanically and commercially milled carapace (MMC and CMC) were the most efficient, removing >95.0 % within 40 minutes from 100-1000 mgIL Cu(II) solutions. Extended studies showed MMC was also applicable for use in biosorption columns and effective for the removal of Cd(II), Hg(II), Pb(II), Ni(lI) and Zn(II), at concentrations ranging from 1-1000 mgIL. MMC and CMC were compared with chitin, chitosan, Darco© and Norit© activated carbons and Dowex© ion-exchange resin for the removal of Cu(II). Dowex© and Norit© were the most efficient commercial sorbents removing up to 99.9 % from the 1-1000 mgIL. MMC and CMC compared favourably and were effective over the 1-4000 mg/L range and suitable for use in acidic solutions (pH 4.2-4.7). Sorption of Cu(II), Hg(II), Pb(II) and Zn(II) by MMC were predicted reliably (R2>0.99) using a pseudo-second-order model, with rates of 1.34, 14.6, 1.37 and 1.30 mg/mg/min respectively. An intra-particle diffusion. model and SEM-EDAX microanalysis revealed that the biosorption of metals proceeds via rapid adsorption-precipitation to surface binding sites, followed by rate limiting intra-particle diffusion. Equilibrium uptakes were evaluated using the Langmuir, Freundlich and Redlich-Peterson adsorption isotherm models. The best fits were obtained for the Langmuir model with 416.7, 86.2, 30.5 and 14.6 mg/g MMC for Pb(II), Cu(II), Zn(II) and Hg(II) respectively. The results show that biosorption of metals is complex and proceeds via adsorption, precipitation, absorption, and ion exchange depending on pH, initial concentration and material conditioning. Although CMC was marginally more efficient than MMC, MMC is less labour intensive and more cost effective to produce. Therefore, MMC offers significant potential as a viable metal biosorbent and merits further development.
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Panesar, Kulvinder. "Conversational artificial intelligence - demystifying statistical vs linguistic NLP solutions". Universitat Politécnica de Valéncia, 2020. http://hdl.handle.net/10454/18121.
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yesThis paper aims to demystify the hype and attention on chatbots and its association with conversational artificial intelligence. Both are slowly emerging as a real presence in our lives from the impressive technological developments in machine learning, deep learning and natural language understanding solutions. However, what is under the hood, and how far and to what extent can chatbots/conversational artificial intelligence solutions work – is our question. Natural language is the most easily understood knowledge representation for people, but certainly not the best for computers because of its inherent ambiguous, complex and dynamic nature. We will critique the knowledge representation of heavy statistical chatbot solutions against linguistics alternatives. In order to react intelligently to the user, natural language solutions must critically consider other factors such as context, memory, intelligent understanding, previous experience, and personalized knowledge of the user. We will delve into the spectrum of conversational interfaces and focus on a strong artificial intelligence concept. This is explored via a text based conversational software agents with a deep strategic role to hold a conversation and enable the mechanisms need to plan, and to decide what to do next, and manage the dialogue to achieve a goal. To demonstrate this, a deep linguistically aware and knowledge aware text based conversational agent (LING-CSA) presents a proof-of-concept of a non-statistical conversational AI solution.
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Breckel, Alex Cade. "Regulating electricity and natural gas in Peru : solutions for a sustainable energy sector". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90029.
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Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 57-59).
Peru is one of the fastest growing countries in Latin America, thanks in part to industry fueled by generous endowments of hydro power capacity and natural gas reserves. However, investment in electricity generation capacity has not kept pace with the rapid increase in demand and threatens to stymie future economic growth. A flawed regulatory environment is to blame, and specific roadblocks to increased generation investments include a dysfunctional capacity payment system, low administratively determined gas prices, and structural barriers to investment in hydro. This thesis provides an overview of the design, functioning and historical context for energy regulation in Peru; identifies the key barriers to generation investment; analyzes two potential regulatory reforms; and recommends the specific reform that has the most promise for reigniting investment in hydro. Two reforms strike at the root of the current problem: The first, increasing the price of natural gas for power generators up to the economic netback value of LNG exports, would make hydro a viable investment but would hit consumers with very large increases in their electricity bills. An alternative approach, a reform to the capacity payment mechanism, could provide the same benefits in terms of drawing new generator investment but at a much lower cost to consumers. It would also offer benefits for regulatory discretion in the future evolution of the grid.
by Alex Cade Breckel.
S.M. in Technology and Policy
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Marzo, i. Grimalt Núria. "Natural Language Processing Model for Log Analysis to Retrieve Solutions For Troubleshooting Processes". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-300042.
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In the telecommunications industry, one of the most time-consuming tasks is troubleshooting and the resolution of Trouble Report (TR) tickets. This task involves the understanding of textual data which can be challenging due to its domain- and company-specific features. The text contains many abbreviations, typos, tables as well as numerical information. This work tries to solve the issue of retrieving solutions for new troubleshooting reports in an automated way by using a Natural Language Processing (NLP) model, in particular Bidirectional Encoder Representations from Transformers (BERT)- based approaches. It proposes a text ranking model that, given a description of a fault, can rank the best possible solutions to that problem using answers from past TRs. The model tackles the trade-off between accuracy and latency by implementing a multi-stage BERT-based architecture with an initial retrieval stage and a re-ranker stage. Having a model that achieves a desired accuracy under a latency constraint allows it to be suited for industry applications. The experiments to evaluate the latency and the accuracy of the model have been performed on Ericsson’s troubleshooting dataset. The evaluation of the proposed model suggest that it is able to retrieve and re-rank solution for TRs with a significant improvement compared to a non-BERT model.En av de mest tidskrävande uppgifterna inom telekommunikationsindustrin är att felsöka och hitta lösningar till felrapporter (TR). Denna uppgift kräver förståelse av textdata, som försvåras as att texten innehåller företags- och domänspecifika attribut. Texten innehåller typiskt sett många förkortningar, felskrivningar och tabeller blandat med numerisk information. Detta examensarbete ämnar att förenkla inhämtningen av lösningar av nya felsökningar på ett automatiserat sätt med hjälp av av naturlig språkbehandling (NLP), specifikt modeller baserade på dubbelriktad kodrepresentation (BERT). Examensarbetet föreslår en textrankningsmodell som, givet en felbeskrivning, kan rangordna de bästa möjliga lösningarna till felet baserat på tidigare felsökningar. Modellen hanterar avvägningen mellan noggrannhet och fördröjning genom att implementera den dubbelriktade kodrepresentationen i två faser: en initial inhämtningsfas och en omordningsfas. För industrianvändning krävs att modellen uppnår en given noggrannhet med en viss tidsbegränsning. Experimenten för att utvärdera noggrannheten och fördröjningen har utförts på Ericssons felsökningsdata. Utvärderingen visar att den föreslagna modellen kan hämta och omordna data för felsökningar med signifikanta förbättringar gentemot modeller utan dubbelriktad kodrepresentation.
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Mayer, Timothy David. "Interactions of phosphorus and colloidal iron oxides in model solutions and natural waters /". Full text open access at:, 1995. http://content.ohsu.edu/u?/etd,214.
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HERZOG, PATRICIA. "Macrostructure des asphaltenes de petrole, leur comportement en milieu naturel et en solution". Paris 6, 1990. http://www.theses.fr/1990PA066545.
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Des asphaltenes issus d'un residu sous vide de brut safaniya ont ete etudies par diffusion centrale des rayons x et des neutrons ainsi que par diffraction x. Une etude systematique de ces particules en solution dans des solvants organiques a ete effectuee. La comparaison entre les deux techniques de diffusion aux petits angles des rayons x et des neutrons a ete possible avec la solution d'asphaltenes a une concentration de 1% en poids dans l'ortho-xylene. Nous avons fait varier plusieurs parametres tels que: le vieillissement des solutions, le changement de solvant et la concentration. Les asphaltenes de petroles se presentent sous la forme de particules planes de faible epaisseur (entre 6a et 10a) et de diametre variant entre 80a et 180a selon la concentration et le solvant dispersant. Ces particules revelent une structure interne agregee. Nous avons constate que le vieillissement ainsi qu'une augmentation de la concentration favorisent l'agregation. Nous avons montre que l'organisation de ces systemes est la meme dans les residus de distillation. L'epaisseur est plus importante et on observe la presence d'arrangements periodiques identiques a ceux presents dans les asphaltenes solides. Nous avons observe qu'une augmentation de temperature dans les solutions entraine une diminution de la taille des particules. Dans les residus, l'augmentation de la temperature a pour effet de desorganiser la structure interne microscopique du systeme
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Dai, Xiang. "Recognising Biomedical Names: Challenges and Solutions". Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/25482.
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The growth rate in the amount of biomedical documents is staggering. Unlocking information trapped in these documents can enable researchers and practitioners to operate confidently in the information world. Biomedical Named Entity Recognition (NER), the task of recognising biomedical names, is usually employed as the first step of the NLP pipeline.
Standard NER models, based on sequence tagging technique, are good at recognising short entity mentions in the generic domain. However, there are several open challenges of applying these models to recognise biomedical names:
● Biomedical names may contain complex inner structure (discontinuity and overlapping) which cannot be recognised using standard sequence tagging technique;
● The training of NER models usually requires large amount of labelled data, which are difficult to obtain in the biomedical domain; and,
● Commonly used language representation models are pre-trained on generic data; a domain shift therefore exists between these models and target biomedical data.
To deal with these challenges, we explore several research directions and make the following contributions: (1) we propose a transition-based NER model which can recognise discontinuous mentions; (2) We develop a cost-effective approach that nominates the suitable pre-training data; and, (3) We design several data augmentation methods for NER.
Our contributions have obvious practical implications, especially when new biomedical applications are needed. Our proposed data augmentation methods can help the NER model achieve decent performance, requiring only a small amount of labelled data. Our investigation regarding selecting pre-training data can improve the model by incorporating language representation models, which are pre-trained using in-domain data. Finally, our proposed transition-based NER model can further improve the performance by recognising discontinuous mentions.
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Walsh, Jessica Claire. "Barriers and solutions to implementing evidence-based conservation". Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709460.
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Donado, Garzón Leonardo David. "On multicomponent reactive transports in porous media: from the natural complexity to analitycal solutions". Doctoral thesis, Universitat Politècnica de Catalunya, 2009. http://hdl.handle.net/10803/5918.
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El transporte de solutos no conservativos en medios porosos o fracturados es altamente influenciado por su heterogeneidad. Complejidad adicional se agrega al proceso de transporte, debido a la presencia de diferentes tipos de reacciones químicas que controlan la evolución de las concentraciones de las especies en el medio. Muchas de esas reacciones químicas están gobernadas por la mezcla de aguas con diferente calidad geoquímica. La mezcla produce desequilibrio químico instantáneo en el agua mezclada resultante, y las reacciones dan lugar para que se re-equilibre el sistema.Esta disertación doctoral estudia el transporte en medios heterogéneos cubriendo diferentes y tipos de acuíferos. Primero, el flujo y el transporte se analizan en rocas fracturadas, las cuales poseen baja permeabilidad. Estas formaciones son estudiadas usando como modelo conceptual las Redes Discretas de Fracturas, donde se considera el medio como una densa red de fracturas que se interconectan y conducen agua. Este modelo de es una alternativa válida para conceptualizar el transporte de solutos en el medio fracturado, pero tradicionalmente no se ha utilizado para analizar ni el transporte ni el flujo en una modelación de tipo problema inverso, debido a su alto costo computacional.
El transporte de solutos conservativos en medios heterogéneos puede modelarse con una ecuación efectiva que involucre un término de transferencia de masa entre la zona móvil y la zona inmóvil. La segunda parte de la disertación explora la posibilidad de extender esta idea para tener en cuenta las especies reactivas. Se parte de la consideración de que las especies están en equilibrio químico local, el cual es alcanzado instantáneamente. El impacto de la heterogeneidad del medio en el transporte efectivo es representado por un modelo de tasa de transferencia múltiple de masa (MRMT), el cual aproxima el medio a un multicontinuo de una región móvil y varias regiones inmóviles, las cuales se relacionan por una transferencia de masa cinética. Partiendo del hecho de que todas las regiones están bien mezcladas, el equilibrio global no se preserva. Esta imposición implica que las reacciones tomen lugar en todo el dominio, y sean dominadas tanto por la dispersión local como por la transferencia de masa. Se derivaron expresiones explícitas para calcular las tasas de reacción en las regiones móvil e inmóvil y se estudió el impacto de la transferencia de masa en el transporte reactivo. Las tasas de reacción pueden cambiar significativamente comparadas con aquellas que se obtendrían en un medio homogéneo. Para una amplia distribución de tiempos de residencia en las zonas inmóviles, el sistema podría tomar mucho más tiempo para equilibrar globalmente el medio comparado que para un medio homogéneo.
El último tema abordado en esta disertación es el análisis del transporte de especies bajo condiciones de cinética química o equilibrio no instantáneo. El transporte reactivo a escala local es analizado bajo dos situaciones: (i) con una reacción sencilla y (ii) con dos reacciones simultáneas: una considerada instantánea y la otra como lenta respecto al tiempo característico de transporte. En la primera situación de las dos planteadas, es posible concluir que el problema puede ser reescrito sólo en términos del estado inicial del sistema más una ecuación diferencial para la tasa de reacción.
El resultado clave es que la tasa de reacción en equilibrio depende de un término relativo a la mezcla y a la reacción cinética, la cual es de hecho el factor que controla la disponibilidad de reactantes en el sistema, y la distribución de las combinaciones lineales de las concentraciones acuosas de las especies, llamadas componentes tanto conservativas como cinéticas. Desde un punto de vista operacional, estas expresiones permiten el cálculo directo de las tasas de reacción en equilibrio sin la necesidad de calcular las concentraciones de las especies acuosas.
Transport of non-conservative species or solutes in porous or fractured media is highly influenced by heterogeneity. Additional complexity is added to the processes due to the presence of different types of chemical reactions that control the fate of species concentrations in the medium. Many of these chemical reactions are governed by mixing of waters with different geochemical signature. Mixing yields instantaneous chemical disequilibrium in the resulting mixed water, and reactions take place to re-equilibrate the system.
This dissertation studies transport in heterogeneous media covering different problems (flow, conservative transport and reactive transport) and in different aquifer types. First, we analyze flow and transport in low permeable highly fractured massifs. These are studied using the Discrete Fracture Network (DFN) approach, where a dense network of water-conducting intersecting fractures is considered. The DFN approach traditionally has lacked the possibility of analyzing transport (as well as flow) in an inverse problem framework. The actual tracer test, performed with a conservative solute (deuterium), evidences Non-Fickian behavior, characterized by tailing in the breakthrough curve.
As a consequence, transport of conservative solutes in heterogeneous media can be modeled with an effective equation involving a mass transfer term between the mobile and some immobile zones. In the second part of the thesis we explore the possibility of extending this idea to account for transport of reactive species. We start by considering species where local chemical equilibrium conditions are reached instantaneously. The impact of the medium heterogeneity on effective transport is represented by a multi rate mass transfer approach, which models the medium as a multiple continuum of one mobile and multiple immobile regions, which are related by kinetic mass transfer. Even though all regions (mobile and immobile) are assumed to be well mixed (local equilibrium), globally equilibrium is not preserved. The imposition of local equilibrium at all points implies the need for reactions to take place all through the domain, driven by both local dispersion and mass transfer. We derive explicit expressions for the reaction rates in the mobile and immobile regions and study the impact of mass transfer on reactive transport. The reaction rates can change significantly compared with the ones that would be obtained in a homogeneous media. For a broad distribution of residence times in the immobile zones, the system may take much more time to equilibrate globally than for a homogeneous medium.
The last topic addressed in this Thesis is the analysis of transport of species undergoing non-instantaneous (kinetic) chemical equilibrium. Reactive transport at the local scale is analyzed under two situations: (i) with a single kinetic reaction and (ii) with two simultaneous reactions: one considered instantaneous and the other one being slow related to the transport characteristic time. In the first problem of these problems, we find that the problem can be rewritten only in terms of the initial state of the system plus a non-linear partial differential equation for the reaction rate.
The key result is that the equilibrium reaction rate depends on a mixingrelated term, the kinetic reaction rate, which is actually controlling the availability of reactants in the system, and the distribution of (conservative and kinetic) linear combinations of aqueous species concentrations. From an operational standpoint, our expressions allow direct computation of equilibrium reaction rates without the need to calculate aqueous species concentrations. To illustrate the results, the dissolution of calcite in the presence of precipitating gypsum in a one-dimensional fully saturated system is analyzed. The example highlights the highly nonlinear and non monotonic response of the system to the controlling input parameters.