Spelling suggestions: "subject:"cnen""
71 |
Radiated Electric and Magnetic Fields Caused by Lightning Return Strokes to the Toronto CN TowerBoev, Ivan Krasimirov 05 August 2010 (has links)
In the present PhD work, three sophisticated models based on the "Engineering" modeling approach have been utilized to conveniently describe and thoroughly analyze details of Lightning events at the CN Tower. Both the CN Tower and the Lightning Channel are represented by a number of connected in series Transmission Line sections in order to account for the variations in the shape of the tower and for plasma processes that take place within the Lightning Channel. A sum of two Heidler functions is used to describe the "uncontaminated" Return Stroke current, which is injected at the attachment point between the CN Tower and the Lightning Channel. Reflections and refractions at all points of mismatched impedances are considered until their contribution becomes less than 1% of the originally injected current wave.
In the proposed models, the problem with the current discontinuity at the Lightning Channel front, commonly taken care of by introducing a "turn-on" term when computing radiation fields, is uniquely treated by introducing reflected and transmitted components.
For the first time, variable speed of propagation of the Return Stroke current front has been considered and its influence upon the predicted current distributions along the whole Lightning Channel path and upon the radiated distant fields analyzed.
Furthermore, as another novelty, computation of the electromagnetic field is accomplished in Cartesian Coordinates. This fact permits to relax the requirement on the verticality of the Lightning Channel, normally imposed in Cylindrical Coordinates. Therefore, it becomes possible to study without difficulty the influence of a slanted Lightning Channel upon the surrounding electromagnetic field.
Since the proposed sophisticated Five-Section Model has the capability to represent very closely the structure of the CN Tower and to emulate faithfully the shape of, as well as physical processes within the Lightning Channel, it is believed to have the potential of truthfully reproducing observed fields.
The developed modeling approach can be easily adapted to study the anticipated radiated fields at tall structures even before construction.
|
72 |
Connection between Severe Weather and Intense LightningYandulska, Kateryna 17 February 2010 (has links)
This Thesis researches, explains and provides conclusions for the question of correlation between data and criteria used by Environment Canada (EC) and Lightning Studies Research Group (LSG) of University of Toronto. The necessity of such correlation arises from the question of common criteria between severe weather, as it shown in graphical data from EC, and intense lighting storms, recorded by LSG, despite deep differences in area, time scale and object of observation used by those two organizations.
The objective of the Thesis is not only to compare those two, very different sets of data and criteria and find out the common ground between them, but also to provide in-depth explanation of criteria, used by Lighting Studies Research Group, along with revisiting and establishing some of them. Eight storm cases, taken from years 2005-2008 provide cases for practical research, which affects intermediate Greater Toronto Area.
|
73 |
Synthèse d'iminosucres d'intérêt thérapeutique / Synthesis of iminosugars with therapeutic potentialDilmac, Alicia Merve 25 June 2012 (has links)
Les iminosucres constituent une famille de puissants inhibiteurs de glycosidases et glycosyltransférases. Ces propriétés inhibitrices confèrent à ces composés un potentiel thérapeutique important pour diverses maladies (maladies virales et lysosomales, diabète, cancers…). Une méthodologie de synthèse d’iminosucres de type 2-cyano-6-oxazolopipéridines trihydroxylées a été récemment mise au point et s’appuie sur la condensation d’un glutaraldéhyde polyhydroxylé et d’une amine chirale, en présence de cyanure de potassium. Le premier objectif de ces travaux de thèse fut l’étude de la réactivité de dérivés du hexahydro-3-phényl-6,7,8-trihydroxy-3R-[3R ,5R ,6S ,7R ,8S ,8aR]-5H-oxazolo[3,2-a]pyridine-5-carbonitrile, obtenu par cette méthodologie de synthèse. A travers cette étude, il nous fut possible de proposer des conditions optimales d’alkylation de ce type de châssis moléculaire en α de la fonction nitrile et de décrire ainsi une dizaine de nouveaux iminosucres. Le second objectif fut l’extension de cette méthodologie à la synthèse de 2-cyano-6-oxazolopipéridines trihydroxylées de configurations diverses. Ceci permit d’accéder à des 2-cyano-6-oxazolopipéridines trihydroxylées de type allose, mannose et galactose entre autre, également précurseurs d’iminosucres pipéridiniques. L’hydrogénation du hexahydro-3-phenyl-6,7,8-trihydroxy-3R-[3R ,5R ,6S ,7R ,8S ,8aR]-5H-oxazolo[3,2-a]pyridine-5-carbonitrile conduit ainsi à un analogue de l’iminosucre naturel D-allo-déoxynojirymicine. Un accès à des iminosucres de type pyrrolidine fut également proposé. La vingtaine de nouveaux iminosucres synthétisés lors de ces travaux de thèse pourront maintenant être soumis à des tests biologiques, en vue de déterminer leurs activités inhibitrices de diverses glycosidases (fucosidases, glucosidases, mannosidases, galactosidases). / Iminosugars are a family of powerful glycosidases and glycosyltransferases inhibitors. These properties give them an important therapeutic potential towards various diseases (viral and lysosomal diseases, diabetes, cancers…). A fast and efficient methodology have been recently elaborated for the synthesis of trihydroxylated 2-cyano-6-oxazolopiperidines. This methodology consists in the condensation of a chiral amine onto a polyhydroxylated glutaraldehyde in presence of potassium cyanide. The first objective of this thesis was the study of the reactivity of hexahydro-3-phenyl-6,7,8-trihydroxy-3R-[3R ,5R ,6S ,7R ,8S ,8aR]-5H-oxazolo[3,2-a]pyridine-5-carbonitrile derivatives, obtained by the methodology previously described. Their modifications were performed by alkylation of the α position to their nitrile. This gave access to ten new iminosugars. The objective of this work was the appplication of the mentioned methodology to the synthesis of configurationally related iminosugars. Trihydroxylated 2-cyano-6-oxazolopiperidines mimicking the allose, mannose and galactose configurations were obtained. These compounds were also suitable precursors for piperidine type iminosugars. For example, the hydrogenation of hexahydro-3-phenyl-6,7,8-trihydroxy-3R-[3R ,5R ,6S ,7R ,8S ,8aR]-5H-oxazolo[3,2-a]pyridine-5-carbonitrile afforded an analog of the natural compound D-allo-deoxynojirimycin. An access to pyrrolidine related iminosugars was also proposed. The biological evaluation of the twenty three new iminosugars obtained through this work will be soon performed against various glycosidases (fucosidases, glucosidases, mannosidases, galactosidases).
|
74 |
Návrh protierozních a protipovodňových opatření proti nepříznivým účinkům soustředěného povrchového odtoku v k.ú. Lužkovice / Protection of the built-up area of the village Dobrouc against the adverse effects of concentrated runoffKulihová, Martina January 2017 (has links)
The aim of the thesis was to evaluate the erosion and drainage conditions in the cadastral Lužkovice under the Complex land consolidation and then the design of protective measures. The impact of climate change was considered and for that reason evaluation and design was made in two versions. The climate change is one of the most important issues of our time.
|
75 |
Hydrological Modelling of Al Auja Earth Dam in the Lower Jordan Valley. / Hydrologisk modellering av Al Auja jorddammen i lägre Jordandalen.Rimfors, Otto, Velichkin, Vadim January 2015 (has links)
In a populated region with very high potential evapotranspiration, where the rainwater falls only during the winter and mostly in the mountains, the need for sustainable water management and fair distribution is crucial. In the West Bank, Palestine, the main potable water source is a karst mountain aquifer system. Precipitation occurs usually in the form of rainfall in the mountainous regions during winter period and recharges the groundwater systems. The water either reaches the surface as spring water, or is extracted through pumped wells. But the scarcity of drinking water in Palestine is not due to lack of water resources or technical knowledge of water extraction but a direct consequence of Israeli policies, water management, breached water rights and the occupation of Palestinian territories. Because of such restrictions, ground water is not an option to provide more freshwater, instead it is suggested to collect rainwater runoff in reservoirs. In 2011, the first surface water dam was built in Palestine in Al Auja, just north of Ariha. It was built as an experimental project for future dams and is therefore a small earth fill dam which will be expanded to collect water also from an adjacent watershed, much larger than the current one. The purpose of this study is to determine how much bigger the reservoir needs to be to safely store the inflowing rainwater runoff in the future. This was achieved through hydrological modelling using the HEC-HMS software which is a physical based model. The data used in this study were: 25 m DEM, land use data, soil data (both from remote sense and field visit), river network map, precipitation data, location of the gauges and geological formations. Field visits and soil tests were also great contributions of insights and knowledge crucial for the project. Hourly time-series data for precipitation for the winters 2011-2012 and 2012-2013 and monthly evapotranspiration for 2010-2011 were used as input to the model. Water level data in Al Uja reservoir with 20 minutes intervals were used to evaluate the simulations. Simulations were first optimized for the current scenario to find sets of parameters that match the changes in water level in the dam reservoir. This was done both for single rainfall events as well as for the whole seasons. The parameters creating the most matching results were used in additional simulations with the adjacent watershed included. The difference in results between the simulations with the current watershed and the expanded one was used to answer how much more water the reservoir would have received during 2011-2012 and 2012-2013 if the larger watershed were included. The model results reveal that the reservoir should have been able to hold about three times as much water as today. Installation of an inflow meter is suggested for the future along with an evaluation of local climate change in precipitation and evapotranspiration.
|
76 |
Modelagem concentrada e semi-distribuída para simulação de vazão, produção de sedimentos e de contaminantes em bacias hidrográficas do interior de São Paulo / Parsimonious and physically-based models to evaluate streamflow, soil loss and pollution in watersheds in the interior of São PauloSantos, Franciane Mendonça dos 11 September 2018 (has links)
A escassez de dados hidrológicos no Brasil é um problema recorrente em muitas regiões, principalmente em se tratando de dados hidrométricos, produção de sedimentos e qualidade da água. A pesquisa por modelos de bacias hidrográficas tem aumentado nas últimas décadas, porém, a estimativa de dados hidrossedimentológicos a partir de modelos mais sofisticados demanda de grande número de variáveis, que devem ser ajustadas para cada sistema natural, o que dificulta a sua aplicação. O objetivo principal desta tese foi avaliar diferentes ferramentas de modelagem utilizadas para a estimativa da vazão, produção de sedimentos e qualidade da água e, em particular, comparar os resultados obtidos de um modelo hidrológico físico semi-distribuído, o Soil Water Assessment Tool (SWAT) com os resultados obtidos a partir de modelos hidrológicos concentrados, com base na metodologia do número da curva de escoamento do Soil Conservation Service (SCS-CN) e no modelo Generalized Watershed Loading Function (GWLF). Buscou-se avaliar e apresentar em quais condições o uso de cada modelo deve ser recomendado, ou seja, quando o esforço necessário para executar o modelo semi-distribuído leva a melhores resultados efetivos. Em relação à simulação da vazão, os resultados dos dois modelos foram altamente influenciados pelos dados de precipitação, indicando que existem, possivelmente, falhas ou erros de medição que poderiam ter influenciado negativamente os resultados. Portanto, foi proposto aplicar o modelo semi-distribuído com dados de precipitação interpolados (DPI) de alta resolução para verificar a eficiência de seus resultados em comparação com os resultados obtidos com a utilização dos dados de precipitação observados (DPO). Para simulação da produção de sedimentos, e das concentrações de nitrogênio e fósforo, o SWAT realiza uma simulação hidrológica mais detalhada, portanto, fornece resultados ligeiramente melhores para parâmetros de qualidade da água. O uso do modelo semi-distribuído também foi ampliado para simular uma bacia hidrográfica sob a influência do reservatório, a fim de verificar a potencialidade do modelo para esse propósito. Os modelos também foram aplicados para identificar quais os impactos potenciais das mudanças no uso do solo previstas e em andamento. Os cenários estudados foram: I – cenário atual, II – cenário tendencial, com o aumento da mancha urbana e substituição do solo exposto e de parte da mata nativa por uso agrícola; III – cenário desejável, complementa o crescimento urbano tendencial com aumento de áreas de reflorestamento. As metodologias foram aplicadas em duas bacias hidrográficas localizadas no Sudeste do Brasil. A primeira é a bacia do rio Jacaré-Guaçu, incluída na Unidade de Gerenciamento de Recursos Hídricos 13 (UGRHI-13), a montante da confluência do rio das Cruzes, com uma área de 1934 km2. O segundo caso de estudo, é a bacia do rio Atibaia, inserida na UGRHI-5, tem uma área de 2817,88 km2 e abrange municípios dos estados de São Paulo e Minas Gerais. Como principal conclusão, o desempenho do modelo semi-distribuído para estimar a produção de sedimentos, e as concentrações de nitrogênio e fósforo foi ligeiramente melhor do que as simulações do modelo concentrado SCS-CN e GWLF, mas essa vantagem pode não compensar o esforço adicional de calibrá-lo e validá-lo. / The lack of hydrological data in Brazil is a recurrent problem in many regions, especially in hydrometric data, sediment yield and water quality. The research by simplified models has increased in the last decades, however, the estimation of hydrossedimentological data from these more sophisticated models demands many variables, which must be adjusted for each natural system, which makes it difficult to apply. At times it is necessary to respond quickly without much precision in the results, in these situations, simpler models with few parameters can be the solution. The objective of this research is to evaluate different modelling tools used estimate streamflow, sediments yield and nutrients loads values, and namely to compare the results obtained from a physically-based distributed hydrological model (SWAT) with the results from a lumped hydrological, the Soil Conservation Service (SCS-CN) and the Generalized Watershed Loading Function (GWLF) model. Both models use the curve number (CN) concept, determined from land use, soil hydrologic group and antecedent soil moisture conditions and were run with a daily time step. We are particularly interested in understanding under which conditions the use of each model is to be recommended, namely when does the addition effort required to run the distributed model leads to effective better results. The input variables and parameters of the lumped model are assumed constant throughout the watershed, while the SWAT model performs the hydrological analysis at a small unit level, designated as hydrological response units (HRUs), and integrates the results at a sub-basin level. In relation to the flow simulation, the results of the two models were highly influenced by the rainfall data, indicating that, possibly, faults or measurement errors could have negatively influenced the results. Therefore, it was proposed to apply the distributed model with high-resolution grids of daily precipitation to verify the efficiency of its results when compared to rainfall data. For simulation of sediment, nitrogen and phosphorus, SWAT performs a more detailed simulation and thus provides slightly better results. The use of the SWAT was also extended to simulate the influence of reservoir, in order to verify the potentiality of the model, in relation to the simulation. The models also were used to identify which are potential impacts of the ongoing land use changes. The scenarios were: I - Current scenario, II - trend scenario, with the increase of urban land and replacement of the exposed soil and part of the native forest by agricultural use; III - desirable scenario complements the trend urban growth with the replacement of exposed soil and part of the agricultural use by reforestation. The methodologies were applied on two watersheds located in the Southeast of Brazil. The first one is the Jacaré-Guaçu river basin, included in the Water Resources Management Unit 13 (UGRHI-13), upstream of Cruzes river confluence, with an area of 1934 km2. The second watershed is the Atibaia River Basin, a part of Water Resources Management Unit 5 (UGRHI-5). It has an area of 2817.88 km2 and covers municipalities of the states of São Paulo and Minas Gerais.
|
77 |
Intégration de la programmation basée entités pour la fabrication sur machines à commandes numériques dans un contexte multi-processLaguionie, Raphael 17 November 2010 (has links) (PDF)
Les travaux présentés portent sur l'intégration de la programmation basée entités des machines-outils à commande numérique (MOCN). Cette programmation émergente s'appuie sur les concepts véhiculés par le standard STEP-NC et la norme ISO 14649. Quatre axes de recherche sont proposés. Le premier concerne l'évolution de la programmation actuelle vers la programmation basée entités et l'enrichissement du standard STEP-NC. Pour ceci, nous proposons deux contributions principales au standard STEP-NC dans le cadre de notre participation au comité normatif de l'ISO 14649 : l'intégration de stratégies d'usinage à motifs avec pour application l'usinage trochoïdal et le tréflage, et l'élaboration d'un modèle fonctionnel STEP-NC des MOCN. Le deuxième axe se focalise sur l'évolution du système de fabrication pour tirer profit de la programmation basée entités. Nous proposons un concept de système étendu de fabrication intégrée XMIS (eXtended Manufacturing Integrated System) ainsi qu'une déclinaison concrète à travers la CAO étendue et la CN étendue. Au cours du troisième axe, nous étendons l'étude à l''intégration de plusieurs procédés au sein d'une même gamme de fabrication STEP-NC et étudions l'organisation des outils de simulation dans ce contexte multi-process avec la description d'espaces de simulation. Le quatrième axe porte sur la validation et la mise en œuvre des concepts proposés avec le développement de la plate-forme SPAIM (STEP-NC Platform for Advanced and Intelligent Manufacturing) qui intégre la programmation basée entités du modèle à la pièce usinée sur des moyens industriels et montre l'impact multidirectionnel des modifications tout au long de la chaîne numérique.
|
78 |
Elaboration et étude des propriétés physico - chimiques de nouveaux composés magnétiquesLe Goff, Xavier 11 April 2006 (has links) (PDF)
Ce travail a été partagé en deux parties dédiées à (i) l'élaboration de sels de C60 (KC60) et la caractérisation de leurs propriétés physico-chimiques ; et (ii) à l'étude et l'analyse des propriétés magnétiques de dérivés du Bleu de Prusse. Notre but a été d'apporter des réponses expérimentales et théoriques aux résultats contradictoires publiés sur ces deux sujets. Pour cela, un effort particulier a été porté sur la maîtrise des conditions de synthèse du KC60 qui nous a permis de contrôler la nature de l'état fondamental. Cette étude a par ailleurs mis en évidence le rôle clef de l'insertion d'atome d'argon sur les propriétés électroniques de ces composés. En ce qui concerne les dérivés du Bleu de Prusse, nous avons montré que l'ordre magnétique observé à basse température est de nature ferrimagnétique et que cette phase magnétique possède une anisotropie magnétique originale induite dans ces matériaux par l'unité Mo(CN)7 4-.
|
79 |
Systém přírodě blízkých protierozních a protipovodňových opatření a jejich optimalizace v procesu pozemkových úprav. / System near natural erosion and flood control measures and optimization of the process of land consolidation.BLÁHA, Vladimír January 2013 (has links)
The thesis is focused on the system erosion and the flood control measures in the cadastral territory of Smetanova Lhota. For the calculation of the erosion threat was used universal soil loss equation (USLE) and runoff characteristics are calculated using the runoff CN - curves. The proposal has the influence of several factors. It's rainfall, vegetation cover, soil characteristics, morphology and other. Several calculations were carried out using the program ERCN.
|
80 |
Determinação de aminoácidos neuroativos em amostras de microdiálise utilizando eletroforese capilar e microchips com detecção por fluorescência / Determination of neuroactive amino acids in microdialysis samples using capillary and microchip electrophoresis with fluorescence detectionCosta, Elton Elias Melo 17 February 2016 (has links)
Specific amino acids (i.e. arginine, citrulline, aspartic acid, histamine, glutamic acid and taurine) play significant roles in a number of physiological processes such as neurotransmission, inflammation and cell proliferation. Analytical methods that are capable of measuring these compounds in small volumes are important for in vivo sampling strategies and single cell analysis. Electrophoresis-based methods (e.g. capillary (CE) and microchip (ME) electrophoresis) with fluorescence detection have been applied to determine various biological compounds due to the high separation efficiency, simplicity, very low sample and solvent volume consumption and short analysis time. In this study, selected amino acids were off-line derivatized with naphthalene-2,3-dicarboxaldehyde/cyanide (NDA/CN-). NDA itself is not fluorescent, but can react with primary amines in the presence of cyanide to produce N-substituted 1-cyanobenz[f]isoindole (CBI) derivatives, which are fluorescent. Run conditions (e.g. buffer additives, organic solvent and separation voltage) were optimized for both methods (CE and ME) to obtain baseline separation of the six analytes. Excitation was accomplished using a diode laser (λex = 445 nm and λem = 490 m). Based on five-point calibration curves, both methods showed good linearity in the range of 10 to 0.1 µmolL-1 for each amino acid. Precision with %RSDs of less than 6.9 and 13.2% was obtained from CE and ME, respectively. For CE, the number of plates (N) was greater than 150 000/m, resolution values were more than 3.4 and migration time was between 11.2 to 18.2 min. ME offered a better efficiency (N > 300 000/m) and resolution (Rs > 3.9) with a much shorter analysis time (3.8 min) than the CE method. Limits of detection and quantification were significantly lower than the concentrations measured in microdialysis sample (MD) for both methods. According to the results with MD, it was possible to identify and quantify all analytes using CE and ME method. A portable fluorescence detection system for use with microchip electrophoresis was developed. Using the portable system with ME, limits of detection for the analytes of interest were 250 nmolL-1 – 1.3 μmolL-1, which were adequate for most analyte detection in brain microdialysis samples. (P.S.: some expressions without training) / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Aminoácidos específicos (arginina, citrulina, ácido aspártico, histamina, ácido glutâmico e a taurina) apresentam funções importantes em vários processos fisiológicos, tais como neurotransmissão, inflamação e proliferação celular. Métodos analíticos que são capazes de quantificar estes compostos utilizando baixo volume de amostra são importantes para estratégias de amostragem in vivo e análises de célula única. Métodos baseados em eletroforese, como eletroforese capilar (EC) e microchip eletroforético (ME), com detecção por fluorescência têm sido utilizados para determinar vários compostos biológicos, devido à elevada eficiência de separação, simplicidade, baixo consumo de amostra, volume do solvente e o curto tempo de análise. Neste estudo, os aminoácidos selecionados foram derivatizados off-line com naftaleno-2,3-dicarboxaldeído/cianeto (NDA / CN-). NDA não é por si só fluorescente, mas pode reagir com aminas primárias na presença de cianeto para produzir 1-cianobenz[f]isoindoline N-substituídos (CBI), que são derivados fluorescentes. As condições de execução, incluindo aditivos no tampão, solvente orgânico e voltagem de separação foram otimizados para ambos os métodos (EC e ME) visando obter adequada resolução de separação para seis analitos. A excitação foi conseguida utilizando um laser de diodo (λex = 445 nm e λem = 490 m). Com base nas curvas analíticas com cinco pontos, os dois métodos demonstraram uma boa linearidade no intervalo de 10 a 0,1 µmolL-1 para cada aminoácido. Precisão com RSD% menor do que 6,9 e 13,2% foram obtidos a partir da técnica de EC e ME, respectivamente. Para EC, o número de pratos teóricos (N) foi maior do que 150 000 / m, com valores de resolução maiores que 3,4; sendo que o tempo de migração variou entre 11,2-18,2 min. ME ofereceu uma melhor eficiência (N> 300 000 / m) e resolução (Rs> 3,9) com um tempo de análise muito mais curto (3,8 minutos) do que o método aplicando EC. Os limites de detecção e quantificação para ambos os métodos foram significativamente menores do que as concentrações medidas nas amostras de microdiálise (MD). De acordo com os resultados com MD, foi possível identificar e quantificar todos os analitos usando o método de EC e ME. Um sistema portátil de detecção de fluorescência para ser utilizado com microchip eletroforético foi desenvolvido. Usando o sistema portátil com o ME, os limites de detecção para os analitos de interesse foram 250 nmolL-1 – 1,3 μmolL-1, que são adequados para a detecção da maioria dos analitos nas amostras de microdiálise cerebral. (OBS.: algumas expressões sem formação)
|
Page generated in 0.0464 seconds