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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
601

Analýza faktorů ovlivňujících přímý odtok z povodí / Analysis of factors affecting the direct runoff

VLASÁK, Ivo January 2016 (has links)
This diploma thesis deals with the analysis of the factors which influence the direct drainage from the drainage area. The thesis specifically deals with the drainage area of the Kopaninský brook. Drainage is always influenced by several factors at the same time. These factors are above all climate, anthropogenic impact, underdrainage, shape and extent of a drainage area, land use, geologic structure, location and altitude of a drainage area. The direct drainage can be separated by different methods (modificated semi-graphical method, GROUND method, method of hydrogram separation, method of digitals filtres) or CN- curves can be used for calculation. This thesis used the method of CN curves to process the results of a given drainage area. In the methodical part of the thesis I reached to the creation of direct drainage maps with the utilisation of the BPEJ maps together with the input data gained by the method of CN curves. These outputs were created at different values of design rains repetition time N= 2, 10, 50 and 100 years. The volume of a direct drainage was calculated by a classic method and by a method using the ArcMap programme. Another part of the thesis was simulation of different area utilisation situations (real condition versus grassing of ploughland) and saturation of drainage area, or more precisely water content in soil (dry soil, middle dry soil, wet soil).
602

An investigation into the efficacy of eggshells as a low cost adsorbent for the removal of potentially toxic inorganic elements from aqueous solutions

Mashangwa, Terence Dambudzo 09 1900 (has links)
Excessive release of metals and metalloids into the environment is a major global environmental concern and there is need for environmentally friendly and cost effective methods for their removal. The present study investigated the adsorptive removal of zinc, lead, copper and nickel ions from synthetic aqueous solutions and various metals from three acid mine drainage (AMD) sites using chicken eggshells. Process parameters including the initial metal concentration were evaluated and the optimum conditions obtained were pH 7, adsorbent dose of 7 g and contact time of 360 minutes (for the removal of 100ppm metal ions). Under these conditions the percentage adsorptions were; 97% for lead, 95% for copper, 94% for nickel and 80% for zinc. Aluminium, iron, potassium, nickel and zinc ions all had percentage adsorptions above 75% in AMD Sample 1. Potassium had a 98.78% adsorption while magnesium, strontium and zinc had 72.33; 68.75 and 53.07% adsorption respectively in Sample 2. Arsenic, chromium, copper, iron, antimony and tellurium ions were above 75% for Sample 3. The study demonstrated the efficacy of chicken eggshells and presents it as a viable low-cost adsorbent for bioremediation. / Environmental Science / M. Sc. (Environmental Science)
603

Évaluation environnementale et géométallurgique de minerais sulfurés polymétalliques, basée sur une approche minéralogique pluridisciplinaire / Environmental assessment of polymetallic sulfide ores based on a multidisciplinary approach

Chopard, Aurélie 20 December 2016 (has links)
Ce travail de thèse a pour objectif de développer une méthodologie permettant de prédire l’impact environnemental des futurs projets miniers, dès l’étape d’exploration. Le drainage minier acide, connu comme le principal problème environnemental des gisements sulfurés, se produit lors de l’oxydation des sulfures par l’oxygène et l’eau. Des échantillons de sulfures et sulfosels ont été soumis à des tests géochimiques afin d’étudier leur taux de réactivité. Les minéraux ont été classés par ordre décroissant: gersdorffite > pyrrhotite > arsénopyrite > Ni-pyrite > Ni-pyrrhotite > Fe-sphalérite > pyrite > galène > chalcopyrite. L’influence des interactions galvaniques sur le taux de réactivité de la pyrite, la chalcopyrite et la sphalérite a été étudiée. La pyrite est protégée galvaniquement en présence de chalcopyrite mais n’est pas complètement protégée en présence de sphalérite. Des mélanges synthétiques de minéraux purs ont permis la modification du calcul de potentiel de génération d’acidité par l’ajout d’un facteur cinétique, basée sur les équations de Paktunc (1999) et Bouzahzah et al. (2013). Dix minerais polymétalliques et aurifères ont été caractérisés selon une méthodologie pluridisciplinaire. La caractérisation minéralogique des minerais a permis de connaître leur composition minéralogique quantitative et de détecter les éléments contaminants ainsi que leur spéciation. Une méthode automatisée de quantification minéralogique basée sur la microscopie optique multispectrale a été développée. Cette innovation vise à développer la microscopie optique pour des applications métallurgiques et environnementales de routine / This thesis proposes the implementation of a reliable methodology, based on the characterization of ores at the exploration stage. The main environmental issues for the mining industry are acid mine drainage and contaminated neutral drainage. Sulfides and sulfosalts, when in contact with water and oxygen, oxidize at different rates, resulting in the production of acid and release of various contaminants. Samples of pure sulfides were submitted to geochemical testing to determine their oxidation rates. The pure minerals can be ordered from the highest to the lowest reactivity as: gersdorffite > pyrrhotite > arsenopyrite > Ni-pyrite > Ni-pyrrhotite > Fe-sphalerite > pyrite > galena > chalcopyrite. Galvanic interactions between pyrite, chalcopyrite, and sphalerite were geochemically investigated. Pyrite was galvanically protected in presence of chalcopyrite, and partially protected in presence of sphalerite. Five synthetic tailings, simulating realistic tailings sulfides compositions, were prepared to compare geochemical behaviors and produce a better assessment of the acid-generation potential (AP). A new method is proposed by adding a kinetic factor. Ten polymetallic and gold sulfide ores were fully characterized with multidisciplinary techniques. Mineralogical investigations allowed for the mineralogical quantification of the ores, and for the knowledge of trace elements and their speciation. A method was developed to automatically quantify sulfides by multispectral optical microscopy. Detailed mineralogical work can save time and money and allows detecting the problems at the beginning of mining developments, improving mine waste management and mine closure planning
604

Estudo morfológico do sistema de drenagem lacrimal no cão

Sampaio, Gabriela Rodrigues [UNESP] January 2005 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:31:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2005Bitstream added on 2014-06-13T18:41:51Z : No. of bitstreams: 1 sampaio_gr_dr_botfmvz.pdf: 1495410 bytes, checksum: cd1d0ecf2c912ddfa90cc41a09e5627e (MD5) / Universidade Estadual Paulista (UNESP) / O mecanismo de drenagem lacrimal do cão não é totalmente conhecido. O objetivo deste estudo foi avaliar a via lacrimal excretora do cão normal do ponto de vista histológico, na tentativa de melhor conhecer esta estrutura. Método: realizou-se um estudo envolvendo 30 cães normais (60 olhos), sem raça definida, adultos, pesando de 4,15 a 30 kg. Esses animais foram submetidos a exame ectoscópico (exame externo), dacriocistográfico e avaliação histológica da via lacrimal excretora. Resultados: a via lacrimal excretora do cão é formada por pontos, canalículos e saco lacrimal, e ducto nasolacrimal, o qual se abre no meato inferior da narina, observados ao exame dacriocistográfico. Histologicamente, a via lacrimal excretora do cão é, em parte, revestida por epitélio escamoso estratificado não queratinizado, o qual repousa em estroma de tecido conjuntivo denso; e, em parte, revestida por epitélio estratificado colunar, repousando em estroma de tecido conjuntivo frouxo. As regiões do saco lacrimal e do ducto nasolacrimal são circundadas por rica rede vascular. Não foram evidenciadas fibras musculares circundando (intimamente dispostas) a via lacrimal excretora do cão, ou justapostas a essa via. Conclusão: o cão não possui estruturas contráteis envolvendo intimamente a via lacrimal excretora, podendo-se supor que o mecanismo de drenagem lacrimal não envolva mecanismos de contração muscular. / The mechanism of lacrimal drainage system in dogs is not still completely understood. The aim of this study was to evaluate the histological aspects of lacrimal drainage system in the healthy dog, trying to know better this anatomical structure. Method: thirty healthy adult cross-bred dogs (sixty eyes), weighting from 4.1 to 30 kg were used in this study. These animals were submited to an extern ophthalmic examination, dacryocystorhinography and a histological analysis of lacrimal drainage route. Results: the lacrimal drainage system is composed by points, lacrimal canaliculi, lacrimal sac and nasolacrimal duct. As showed at the dacryocystorhinography, the nasolacrimal duct opens towards to the meato inferior da narina. By the histological analysis, the lacrimal drainage route is partially composed by non-keratinized stratified squamous epithelium which lies on dense conjunctive tissue stroma, and partially covered by stratified columnar epithelium over a layer of cells of loose conjunctive tissue stroma. The lacrimal sac and nasolacrimal duct areas are rounded by a well developed blood vessels net. It were not observed muscle fibers rounding, or nearby, the lacrimal drainage route. Conclusion: contractile structures rounding lacrimal drainage route were not observed in the dog. We supposed that the mecanism of lacrimal drainage is not related to a muscle contractile responses.
605

Evolution du refroidissement, de l'exhumation et de la topographie des arcs magmatiques actifs : exemple des North Cascades (USA) et de zone de faille Motagua (Guatemala) / Cooling, exhumation and topographic evolution in continental magmatic arcs : an integrated thermochronological and numerical modelling approach : example from North Cascades (U.S.A.) and the Motagua fault zone (Guatemala)

Simon-Labric, Thibaud 27 January 2011 (has links)
Cette thèse cible l'étude de la structure thermique de la croûte supérieure (<10km) dans les arcs magmatiques continentaux, et son influence sur l'enregistrement thermochronologique de leur exhumation et de leur évolution topographique. Nous portons notre regard sur deux chaînes de montagne appartenant aux Cordillères Américaines : Les Cascades Nord (USA) et la zone de faille Motagua (Guatemala). L'approche utilisée est axée sur l'utilisation de la thermochronologie (U-Th-Sm)/He sur apatite et zircon, couplée avec la modélisation numérique de la structure thermique de la croûte. Nous mettons en évidence la variabilité à la fois spatiale et temporelle du gradient géothermique, et attirons l'attention du lecteur sur l'importance de prendre en compte la multitude des processus géologiques perturbant la structure thermique dans les chaînes de type cordillère, c'est à dire formées lors de la subduction océanique sous un continent. / This thesis focuses on the influence of the dynamic thermal structure of the upper crust (<10km) on the thermochronologic record of the exhumational and topographic history of magmatic continental arcs. Two mountain belts from the American Cordillera are studied: the North Cascades (USA) and the Motagua fault zone (Guatemala). I use a combined approach coupling apatite and zircon (U-Th-Sm)/He thermochronology and thermo-kinematic numerical modelling. This study highlights the temporal and spatial variability of the geothermal gradient and the importance to take into account the different geological processes that perturb the thermal structure of Cordilleran-type mountain belts (i.e. mountain belts related to oceanic subduction underneath a continent).
606

Écoulements lors d'inondations en milieu urbain : influence de la topographie détaillée et des échanges avec le réseau d'assainissement / Flows during floods in urban areas : influence of the detailed topography and exchanges with the sewer system

Bazin, Pierre-Henri 05 December 2013 (has links)
Le but de cette thèse est d'étudier la modélisation détaillée des écoulements qui ont lieu lors des inondations urbaines. Dans une première partie, des écoulements en bifurcation incluant des petits obstacles génériques ou des profils de canaux avec trottoirs sont étudiés sur une maquette expérimentale, puis simulés numériquement avec le modèle bidimensionnel Rubar20. Les résultats expérimentaux et numériques montrent l'avantage d'inclure des obstacles de petite taille dans un modèle d'inondation urbaine, alors qu'il n'y a qu'un intérêt limité à utiliser une topographie détaillée des rues. Dans une deuxième partie, les interactions entre écoulements de surface et écoulements en conduites souterraines sont étudiées. Un modèle physique de système de drainage urbain permet de valider un modèle analytique prédisant les débits d'échange entre les deux couches d'écoulement. Une modélisation 1D/2D (conduite/rue) est mise en place avec les modèles Rubar3/Rubar20 et validée sur des écoulements expérimentaux observés sur le modèle physique. Dans une troisième partie, les inondations dans la ville d'Oullins (près de Lyon, France) sont étudiées. La modélisation des écoulements de surface est validée avec des données de terrain, et nous discutons l'intérêt de plusieurs représentations du milieu urbain. L'intégration du réseau d'assainissement dans un modèle 1D/2D reste affectée par plusieurs incertitudes, mais cette étape montre l'intérêt de la modélisation couplée pour décrire les interactions complexes des écoulements lors d'inondations urbaines, ainsi que les limites de l'approche développée pour les écoulements à faible profondeur / Aim of this thesis is to study the detailed modelling of flows that occur during urban floods. In a first part, bifurcation flows including small obstacles or channel profiles with sidewalks are studied on an experimental facility, and then numerically simulated with the two dimensional model Rubar20. Experimental and numerical results show the benefits of including small obstacles in an urban flood model, whereas there is only little benefit of using a detailed representation of the streets topography. In a second part, interactions between surface and underground pipe flows are studied. A physical model of an urban drainage system allows the validation of an analytical model predicting exchange discharges between both flow layers. A 1D/2D modelling (pipe/street) is set up with the models Rubar3/Rubar20 and validated on experimental flows observed on the physical model. In a third part, floods in the city of Oullins (near Lyon, France) are studied. Surface flows modelling is validated with field data, and we discuss the interest of several representations of the urban area. Integration of the sewer system in a 1D/2D model remains impacted by several uncertainties, yet this step shows the interest of the coupled modelling to describe complex flows interactions during urban floods, as well as limitations of the developed approach for shallow flows
607

Dynamique rapide dans les mousses liquides : expériences de drainage et de vibration à l’échelle d’un bord de Plateau / Fast dynamic in liquid foams : drainage and vibrations experiments at the Plateau border scale

Cohen, Alexandre 22 September 2015 (has links)
Je reporte ici une étude expérimentale sur la réorganisation inertielle de liquide dans un microcanal, constitutif des mousses liquides, appelé le bord de Plateau qui est soutenu par trois films de savon. Deux perturbations sont appliquées sur un bord de Plateau. Premièrement, une goutte y est ajoutée. La viscosité du liquide et taille initiale du bord de Plateau et de la goutte sont variés. La redistribution du liquide ajouté est pilotée par les forces capillaires. On observe un régime inertiel où un ressaut hydraulique capillaire se déplace à vitesse et géométrie constantes dans le bord de Plateau. Ce régime est décrit théoriquement et révèle le rôle majeur joué par les films de savon. On observe aussi un régime dominé par les effets visqueux où le liquide ajouté est redistribué selon une dynamique de type diffusive. La transition entre les deux régimes dépend des paramètres de contrôle du système et est caractérisée. La seconde perturbation est acoustique. Une plaque vibrante perturbe le bord de Plateau et les films. La taille du bord de Plateau, la fréquence et l’amplitude de forçage sont variées. Une onde de flexion se propage dans les films qui ont le bord de Plateau pour condition limite fixe ou libre selon sa masse. A haute amplitude, un régime non linéaire apparaît et le liquide dans le bord de Plateau se réorganise en trois zones de taille et d’amplitude d’oscillation très contrastées. Dans chacune des zones, le déphasage entre l’onde dans le film et l’onde dans le bord de Plateau est différent. Le système couplé du film et du bord de Plateau est modélisé par un oscillateur forcé dont la fréquence propre dépend de la fréquence de forçage. / I report an experimental study of inertial liquid reorganization into a liquid foam microchannel, also called a Plateau border supported by three soap films. Two perturbations are applied on the Plateau border. Firstly, a liquid drop is injected. Liquid viscosity, drop size and Plateau border size are changed. The liquid redistribution is drived by capillary forces. We observe an inertial regime where a capillary hydraulic jump move on the Plateau border with a constant shape and a constant velocity. This regime is modeled and shows the importance of soap films. We also observe a viscous-dominated regime where the added liquid is redistributed with a diffusive-like dynamic. The transition between the two regimes is investigated and qualitatively accounted for. Secondly, the Plateau border and the three films are vibrated by a plate. A bending wave is shown to propagate in the soap films with the Plateau border for free or fixed limit conditions according to its mass. For high amplitudes, a non linear regime appears and the liquid inside the Plateau border is redistributed along three zones of very contrasted size and oscillation amplitudes. In each zone, the phase difference between the wave in soap films and the wave in Plateau border is different. The system composed of films and the Plateau border is modelled by a forced oscillator with a resonance frequency which depends on the forced frequency.
608

Connaissances et modélisations pour la gestion du pluvial en zone urbaine : application à la ville de Nice / Knowledge base and modelling for urban stormwater management : application to Nice, France

Salvan, Leslie 18 December 2017 (has links)
Les contours théoriques en hydrologie, hydraulique et les outils de calcul correspondants sont largement développés et utilisés dans le monde. Cependant en parallèle, des problématiques importantes surviennent pendant les crises sans pouvoir être résolues et des solutions développées peinent à être implémentées. En plus, le changement climatique ne va pas faciliter les choses. Pour noircir le tableau, les moyens économiques locaux en France ne vont pas augmenter pour aider les communes à s’attaquer au problème. L’objectif de cette thèse est de conduire une investigation des moyens à disposition pour améliorer notre connaissance locale des concepts en lien avec le pluvial pour permettre une modélisation efficiente. La méthodologie proposée est composée de trois étapes évolutives incluant : 1. Une analyse approfondie des données topographiques locales ; 2. L’évaluation des interactions entre les écoulements de surface et le souterrain ; 3.Une approche intégrée permettant de modéliser les inondations générées par la pluie en zone urbanisée. Les résultats de l’étape 1 montrent que la donnée topographique est essentielle pour la définition des chemins d’écoulement et impactent significativement les résultats de modélisation hydrauliques. Ceci conduit à l’étape 2 lors de laquelle on observe que les débordements provenant du réseau souterrain contribuent à l’inondation mais seulement en partie. Les volumes d’inondations générés par le ruissellement de surface devraient être inclus dans les modèles d’inondation. L’étape 3 présente une configuration possible de modèle intégré permettant de mieux représenter les processus réels en jeu. / Theoretical background about hydrology, hydraulics and computational tools and methods are widely developed and worldwide used. In the same time however, important issues during flood crisis are not solved and practical solutions take time to be implemented. On top of that, ongoing climatic change will not make things easier and intense events will increase in frequency. To worsen the picture, local economic means in France will not increase to help municipalities and local communities to tackle the issue. The objective of this thesis is to investigate on the available ways to improve our local knowledge of stormwater related concepts to allow an efficient modelling. The proposed methodology consists in a three-step-approach including: 1. A thorough analysis of local topography data; 2. The assessment of sewer-surface interactions; 3. An integrated approach to model pluvial flood in urban areas. The results of Step 1 show that topography data is essential in flow path definition and significantly impacts hydraulic modelling results. This leads to Step 2 where it is seen that sewer overflow is one aspect of urban flood issues but represents only part of flood sources. Overland flow generated by runoff should be included in flood models. Then Step 3 presents that integrated urban pluvial modelling is possible with existing tools and can represent the real processes better. This proposed modelling approach should not be disconnected from the reality of stormwater management practical aspects and current constraints. It is shown how complementary actions can be taken to enrich local knowledge and memory thus allowing a more efficient and wiser modelling process.
609

Pumpstationen mit Heberauslässen - ein Beitrag zur Intensivierung der Be- und Entwässerung in der Landwirtschaft

Bollrich, Gerhard 15 January 1976 (has links)
Mit der Intensivierung der landwirtschaftlichen Produktion gewinnen Pumpstationen für die Be- und Entwässerung landwirtschaftlicher Nutzflächen zunehmend an Bedeutung. Zur Beseitigung schädlicher Bodennässe werden offene Gräben oder Dränrohrleitungen angelegt, welche das Wasser bei nicht vorhandener Vorflut einem Entwässerungsschöpfwerk zuleiten. Dieses Schöpfwerk fördert das Wasser aus einem Speicherraum (Mahlbusen) in den Vorfluter. In der DDR sind zahlreiche derartige Entwässerungsschöpfwerke vorhanden. (...):1. Einleitung S. 1 2. "Konventionelle" Pumpstationen S. 4 3. Pumpstationen mit Heberauslässen S. 9 4. Ökonomischer Vergleich S. 22 5. Vergleich mit anderen Anwendungsarten des Hebers S. 32 6. Gegenwärtiger Stand der hydraulischen Berechnung von Heberauslässen und Aufgabenstellung für eigene Untersuchungen S. 43 7. Hydraulische Versuche an Heberauslässen S. 47 8. Betriebsverhalten und hydraulische Berechnung von Heberauslässen S. 56 9. Zusammenfassung und Ausblick S. 186 10. Literatur-, Konsultations- und Exkursionsverzeichnis S. 190 11. Symbolverzeichnis S. 200
610

Evaluating drainage water recycling in tile-drained systems

Benjamin D Reinhart (8071469) 03 December 2019 (has links)
<p>Drainage water recycling (DWR) is the practice of capturing, storing, and reusing subsurface drained agricultural water to support supplemental irrigation and has recently been proposed as a practice for improving the crop production and water quality performance in the tile-drained landscape of the U.S. Midwest. This study describes the development of a modeling framework to quantify the potential irrigation and water quality benefits of DWR systems in tile-drained landscapes and the application of the model using ten years of measured weather, tile drain flow and nutrient concentrations, water table, and soil data from two sites in the U.S. Midwest. From this modeling framework, the development and testing of an open-source online tool is also presented.</p><p></p><p>A spreadsheet model was developed to track water flows between a reservoir and drained and irrigated field area at each site. The amount of tile drain flow and associated nutrient loads that could be captured from the field and stored in the reservoir was estimated to calculate the potential water quality benefits of the system. Irrigation benefits were quantified based on the amount of applied irrigation annually. A reservoir size representing 6% to 8% of the field area with an average depth of 3.05 m was sufficient in meeting the annual irrigation requirements during the 10-year period at each site. At this reservoir size, average annual nitrate-N loads were reduced by 20% to 40% and soluble reactive phosphorus loads by 17% to 41%. Variability in precipitation within and across years, and differences in soil water characteristics, resulted in a wide range of potential benefits at the two sites.</p><p>An online tool was developed from the model, and a variance-based global sensitivity analysis was conducted to determine influential and low-sensitivity input parameters. The input parameter, depth of root zone, was the most influential input parameter suggesting that the estimation of total available water for the field water balance is a critical component of the model. Input settings describing the irrigation management and crop coefficients for the initial establishment and mid-season crop growth periods were also influential in impacting the field water balance. Reservoir seepage rate was influential in regard to the reservoir water balance, particularly at larger reservoir sizes. Sensitivity analysis results were used to develop a user-interface for the tool, Evaluating Drainage Water Recycling Decisions (EDWRD).</p><p>This study shows that DWR is capable of providing both irrigation and water quality benefits in the tile-drained landscape of the U.S. Midwest. The developed modeling framework supports future research on the development of strategies to implement and manage DWR systems, and the online tool serves as a resource for users to increase their awareness and understanding of the potential benefits of this novel practice.</p><p></p>

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