Dissertations / Theses on the topic 'Surfaces – Erosion'
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Kaye, Peter Langford. "The erosive cleaning of surfaces." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364393.
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Marques, Neto Roberto [UNESP]. "Compartimentação do meio físico, evolução morfológica e aspectos morfotectônicos em São Thomé das Letras (MG)." Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/95587.
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marquesneto_r_me_rcla.pdf: 2544757 bytes, checksum: c23c3787ee6420768ab406cae71bd6c2 (MD5)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
O propósito da presente dissertação consiste na determinação de unidades de paisagem para o município de São Thomé das Letras (MG), no estudo da evolução morfológica da área e na apreciação de aspectos morfotectônicos. O cumprimento dos objetivos estipulados demandou uma série de dispositivos analíticos que se coadunaram para a interpretação da fisiologia da paisagem e para o discernimento de diferentes unidades paisagísticas representadas em documento cartográfico de síntese. O estudo da evolução morfológica demandou a avaliação de elementos do quadro genético-evolutivo regional como meio para o entendimento dos processos operantes em âmbito local. A pesquisa focalizou a ocorrência e posicionamento de diferentes superfícies de erosão na área de estudo, diferenciando remanescentes relacionados à Superfície Sul-Americana, do Terciário Inferior, de modelados de dissecação mais recentes, de idade plio-pleistocência. A esta etapa se somou, com ênfase, estudos interessados na evolução morfológica levada a efeito durante o Quaternário em consonância com as oscilações climáticas que marca o referido período, o que se deu por meio do estudo de processos de pedimentação recente e dos depósitos correlatos, da avaliação da cobertura vegetal atual e dos fenômenos cársticos operantes, também sendo estimada a evolução do relevo com enfoque na estrutura, que confere tipicidade apalachiana para a morfologia local e regional. No tocante aos aspectos morfotectônicos, a pesquisa se valeu da análise do relevo e da drenagem, enfando os fenômenos neotectônicos com base na identificação de feições morfológicas indicativas (shutter ridges, capturas, migração lateral de cursos dágua, canais fluviais com trechos excessivamente retilíneos, etc.) e na identificação e interpretação dos principais lineamentos. Os estudos morfotectônicos...
The aim of this present dissertation consists in the determination of landscape unity for the town of São Thomé das Letras (MG), in the study of the area morphological evolution and appreciation of morphotectonic aspects. The fulfilment of stipulated purpose demanded a serie of analytical device that were gathered for the comprehention of landscape phisiology as well as the understanding of different landscape unities represented in graphic-chart document of synthesis. The study of morphological evolution demanded the evaluation of components the regional genetic-evolutive chart as so as to understand the operating process in local range. The research focused the occurence and status of different erosion surface in the studied area, differenciating remainders related to Superfície Sul-Americana of low Terciary, of latest dissection molded, of plio-pleistocene age. To such stage, with emphasis, was added studies interested in the morphological evolution effectuatedduring the Quaternary in consonance with climatic fluctuations that mark the referred era, which happened by means of process study of recent pedimentation and correlated deposits from evaluation of current vegetal covering and operating carstic phenomenon, also evolution of relief beig estimated focusing the structure, that grants appalachian tipicality to regional and local morphology. Regarding the morphotectonic aspects, the research turned to the relief analisis and drainage emphasizing the neotectonic phenomena based on identification of indicative morphological features (shutter ridges, captures, water-course lateral migration, river channel with excessively right-lined streches, etc.) and identification and interpretation of main lineages. The morphotectonic studies were subsidized by measuring the geomorphic rate useful for estimating neotectonic effects, notoriously the asymmetry Factor of Drainage Basins... (Complete abstract click electronic access below)
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Thomas, Petros. "Novel optical studies of ion-erosion, growth, and diffusion on metal surfaces /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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Baugh, Nicole Faith. "Fluvial Channels On Titan." Thesis, The University of Arizona, 2008. http://hdl.handle.net/10150/193368.
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We present channel length and stream order for possible fluvial channels present in Cassini Synthetic Aperture Radar (SAR) data from Ta to T19. These features are present at most latitudes observed, with the bulk of the channels located in near-equatorial latitudes. Many of them are also organized into four branching channel networks, three of third order and one of fourth order, similar to river systems on Earth and Mars. These networks appear well integrated, with few streams that are not incorporated into the higher order branches. The median channel length for all channels on Titan is 29 km, with the longest channels all being incorporated into the channel networks. Estimates of channel width and depth of 1 km and 100m respectively result in a channel volume of 1012 m3 which, when extrapolated to the entire surface of Titan results in 1013 m3 of sediment.
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Marques, Neto Roberto. "Compartimentação do meio físico, evolução morfológica e aspectos morfotectônicos em São Thomé das Letras (MG) /." Rio Claro : [s.n.], 2007. http://hdl.handle.net/11449/95587.
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Orientador: Adler Guilherme ViadanaBanca: Archimedes Perez Filho
Banca: Francisco Sérgio Bernardes Ladeira
Resumo: O propósito da presente dissertação consiste na determinação de unidades de paisagem para o município de São Thomé das Letras (MG), no estudo da evolução morfológica da área e na apreciação de aspectos morfotectônicos. O cumprimento dos objetivos estipulados demandou uma série de dispositivos analíticos que se coadunaram para a interpretação da fisiologia da paisagem e para o discernimento de diferentes unidades paisagísticas representadas em documento cartográfico de síntese. O estudo da evolução morfológica demandou a avaliação de elementos do quadro genético-evolutivo regional como meio para o entendimento dos processos operantes em âmbito local. A pesquisa focalizou a ocorrência e posicionamento de diferentes superfícies de erosão na área de estudo, diferenciando remanescentes relacionados à Superfície Sul-Americana, do Terciário Inferior, de modelados de dissecação mais recentes, de idade plio-pleistocência. A esta etapa se somou, com ênfase, estudos interessados na evolução morfológica levada a efeito durante o Quaternário em consonância com as oscilações climáticas que marca o referido período, o que se deu por meio do estudo de processos de pedimentação recente e dos depósitos correlatos, da avaliação da cobertura vegetal atual e dos fenômenos cársticos operantes, também sendo estimada a evolução do relevo com enfoque na estrutura, que confere tipicidade apalachiana para a morfologia local e regional. No tocante aos aspectos morfotectônicos, a pesquisa se valeu da análise do relevo e da drenagem, enfando os fenômenos neotectônicos com base na identificação de feições morfológicas indicativas (shutter ridges, capturas, migração lateral de cursos dágua, canais fluviais com trechos excessivamente retilíneos, etc.) e na identificação e interpretação dos principais lineamentos. Os estudos morfotectônicos... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The aim of this present dissertation consists in the determination of landscape unity for the town of São Thomé das Letras (MG), in the study of the area morphological evolution and appreciation of morphotectonic aspects. The fulfilment of stipulated purpose demanded a serie of analytical device that were gathered for the comprehention of landscape phisiology as well as the understanding of different landscape unities represented in graphic-chart document of synthesis. The study of morphological evolution demanded the evaluation of components the regional genetic-evolutive chart as so as to understand the operating process in local range. The research focused the occurence and status of different erosion surface in the studied area, differenciating remainders related to Superfície Sul-Americana of low Terciary, of latest dissection molded, of plio-pleistocene age. To such stage, with emphasis, was added studies interested in the morphological evolution effectuatedduring the Quaternary in consonance with climatic fluctuations that mark the referred era, which happened by means of process study of recent pedimentation and correlated deposits from evaluation of current vegetal covering and operating carstic phenomenon, also evolution of relief beig estimated focusing the structure, that grants appalachian tipicality to regional and local morphology. Regarding the morphotectonic aspects, the research turned to the relief analisis and drainage emphasizing the neotectonic phenomena based on identification of indicative morphological features (shutter ridges, captures, water-course lateral migration, river channel with excessively right-lined streches, etc.) and identification and interpretation of main lineages. The morphotectonic studies were subsidized by measuring the geomorphic rate useful for estimating neotectonic effects, notoriously the asymmetry Factor of Drainage Basins... (Complete abstract click electronic access below)
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Cornejo, Marina Inés [Verfasser]. "Pattern formation on Si surfaces by low-energy ion beam erosion / Marina Inés Cornejo." Aachen : Shaker, 2011. http://d-nb.info/1070150231/34.
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Freitas, De Abreu Marcio. "Experimental Study of Metallic Surfaces Exposed to Cavitation." Thesis, KTH, Materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231937.
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Cylinder liners in heavy-duty truck engines are subjected to intense vibrations and may sustain damage from the cavitation of bubbles in the coolant liquid, with some risks of leakage and engine breakdown. An ultrasonic oscillating probe was used to simulate the pitting rates and behavior of samples extracted from cylinder liners, which are made of grey cast iron, with differences in surface roughness, glycol and inhibitor content in coolant, coolant temperature and graphite flake class; bainitic microstructures were also tested. Measurements consisted of mass losses under set intervals during experiments lasting 2.5 or 4 hours. Affected surfaces were later evaluated with scanning electron microscopy and confocal microscopy. Results indicate higher cavitation damage with: lower concentrations of glycol and absence of corrosion/cavitation inhibitors in the coolant liquid, lower liquid temperatures between 76⁰C and 90⁰C, and presence of B-type graphite class in the microstructure. Results regarding surface roughness were inconclusive. A sequence of surface damage mechanisms has been proposed, with corresponding microscope observations, to explain the mass loss trends and the associated microstructural changes over time.
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Cornejo, Marina Inés Verfasser], and Frank [Akademischer Betreuer] [Mücklich. "Pattern formation on Si surfaces by low-energy ion beam erosion / Marina Inés Cornejo. Betreuer: Frank Mücklich." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2011. http://d-nb.info/1051326745/34.
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Cornejo, Marina Inés [Verfasser], and Frank [Akademischer Betreuer] Mücklich. "Pattern formation on Si surfaces by low-energy ion beam erosion / Marina Inés Cornejo. Betreuer: Frank Mücklich." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:291-scidok-42503.
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Levandovsky, Artem. "Structure and dynamics of interfaces in the epitaxial growth and erosion on (110) and (100) crystal surfaces." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3731.
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Thesis (Ph. D.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains vii, 129 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.
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Tabor, Nathan Kyle. "Development of solution techniques and design guidelines for equestrian trails on public lands." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5023.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on November 6, 2007) Includes bibliographical references.
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Hermansson, Jakob, and Emma Wahlström. "Materialval för minskat slitage av sandformningsverktyg." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-13776.
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På Volvo Group Trucks Operations (GTO) i Skövde tillverkas cylinderblock, cylinderhuvud och svänghjul genom gjutning med sandformar. Då formverktygen som formar sandformarna fylls uppkommer slitage där sandpartiklarna träffar, vilket leder till att formverktygen behöver underhållas regelbundet.Målet med denna studie är att hitta alternativa material som formverktygen kan tillverkas i alternativt förstärkas eller beläggas med för att minska slitaget i formverktygen och på så sätt minska kostnader genom att förlänga underhållsintervallen. Problemet analyseras och en litteraturstudie kring erosiv och abrasiv nötning genomförs.Ett antal material tas fram genom en materialvalsprocess som lämpliga kandidater baserat på litteraturstudien, materialkartor och diskussion. Materialprover testas med en standardmetod för erosion med gasburna partiklar. Resultat från tidigare empiriska studier tyder på att erosion påverkas starkt av materialegenskaper så som hårdhet och seghet men även de eroderande partiklarnas infallsvinkel och hastighet.Erosionstestet utförs för 30 och 90 graders infallsvinkel. Testet visar att de mjukare stålen, Holdax och Sverker 21, har högre beständighet mot erosion vid låga infallsvinklar och det hårdare stålet Nimax har högre beständighet vid höga infallsvinklar. Nimax anses vara ett lämpligt material till formverktyget då Nimax har den totalt lägsta erosionstakten vid hopslagning av den totala erosionstakten över båda infallsvinklarna. Nimax har den lägsta erosionstakten vid 30 graders infallsvinkel och anses även ha god beständighet mot erosion vid 90 graders infallsvinkel.Rekommendation ges kring upprepade erosionstester för att säkerställa resultatet. Rekommendationer finns också kring materialprovning i formverktyget för att se om ett materialbyte skulle leda till besparingar. Undersökning av möjligheter att konstruera bort nötning i formverktyget genom ändring av infallsvinklar mellan den inblåsta sanden och formverktyget, samt ändring av lufttryck rekommenderas.At Volvo Group Trucks Operations (GTO) in Skövde, cylinder blocks, cylinder heads and flywheels are manufactured through sandcasting. As the forming tools that forms the sand forms are filled with sand, wear occurs where the sand particles hit the tool surface. The forming tool thus needs to be regularly maintained. The aim of this study is to evaluate alternative materials that the forming tools can be manufactured in to reduce wear, and thereby reducing costs by extending maintenance intervals. The problem is analyzed and a literature study on erosive and abrasive wear is carried out. A number of materials are presented as suitable candidates based on the literature study, material charts and discussion. Material samples are tested using a standard method for solid particle erosion using gas jets. Results from previous empirical studies indicate that erosion is strongly influenced by material properties such as hardness and toughness but also the angle of impingement and velocity of the erosive particles.The erosion test is performed at 30 and 90 degree angle of impingement. The test shows that the softer steel, Holdax and Sverker 21 have higher resistance to erosion at low angles of impingement and the harder steel Nimax has higher resistance at high angles of impingement. Nimax is considered a suitable material for the forming tool, as Nimax has the overall lowest erosion rate when adding the total erosion over both angles of impingement. Nimax has the lowest erosion rate at 30 degrees angle and is also considered to have good resistance to erosion at 90 degrees angle. Recommendation is given on repeated erosion tests to validate the results. There are also recommendations regarding material testing in the forming tool to see if a material change would lead to savings. Examination of possibilities to make changes in the sand filling process, altering angle of impingement between the sand blown and the forming tool as well as air pressure is recommended.
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Bragança, Mário Teixeira Rodrigues. "Superfícies de erosão do setor centro-oriental da Bacia do Rio Paracatu, no Estado de Minas Gerais." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/8/8135/tde-29082012-091211/.
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A regularidade do relevo da bacia hidrográfica do rio Paracatu, inserida no Escudo Atlântico, preserva uma coluna estratigráfica em suas condições originais de deposição e com registros de movimentos crustais de pequena dimensão. Por isso, bucou-se associar a evolução da geomorfologia da bacia do rio Paracatu aos materiais e estrutura, na busca da compreensão da evolução do relevo da área; para tanto, foram consideradas as sucessões sedimentares, discordâncias e patamares erosivos, condição necessária para identificar e descrever padrões geomórficos regulares na paisagem. Revisão da bibliografia geológica e geomorfológica, manipulação da cartografia geológica e topográfica e sua integração e tratamento em SIG, a construção de perfis topográficos a partir de um modelo digital de terreno e campanhas de reconhecimento de campo nortearam os trabalhos, levando à identificação e descrição de quatro superfícies erosivas que registram as marcas da evolução geomorfológica regional: Superfície de Planaltos Tabulares, Superfície de Planaltos Tabulares com Vales Encaixados, Superfície de Planaltos Baixos com Pedimentos Ravinados e Vales Encaixados e Superfície da Depressão da Planície Fluvial do Rio Paracatu, ponto de convergência da reconstituição da história geomorfológica da área de estudo, resultando na composição de um mapa de superfícies de erosão.The regularity of the relief of Paracatu Catchment inserted into Atlantic Shield, is preserved in weathering and erosion resistant rocky layers. It is organized in a stratigraphic column wich keeps its original conditions of deposition with recordings of small dimension crustal movements, allowing the ideal theoretical conditions for the study of erosion surfaces. To associate the evolution of geomorphology of Paracatu River Catchment to material and structure, looking for explanations to the preservation of erosion surfaces in the arrangement of sedimentary successions, unconformities and erosive plateaus were the conditions to identify and describe four surfaces wich record the regional morphological evolution: Tabular Plateau Surface, Tabular Plateau Surface with Dissected Valleys, Low Tableland with Ravined Pedments and Dissected Valleys Surface, and Paracatu River Fluvial Plain Depression Surface. A broad fieldwork through a general and regional approach, followed by an intense bibliographic review and manipulation of topographic and geologic maps and its manipulation in GIS, through a development of a Digital Terrain Model and many topographic profiles, allowed to describe the relief in suggesting the reconstitution of the geomorphological history of the study area, resulting in an erosion surfaces map. The origin of this erosion surfaces can be correlated to four tectonic cycles, that elevated the Brazilian Platform since the Cretaceous until Pleistocene, with drainage incision and dissection of the landscape.
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Santos, Antonio Carlos de Araújo. "Morfologia e topografia de superfícies de aço inoxidável duplex UNS S32205, submetidas à erosão por impactos de partículas de alumina em fluxo de ar." Universidade do Estado do Rio de Janeiro, 2015. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=9392.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorOs aços inoxidáveis duplex vêm sendo cada vez mais utilizados em aplicações que demandam maior resistência à corrosão que os aços inoxidáveis tradicionais. Suas aplicações em estruturas ao ar livre, ou submersas, motivam estudos sobre seu desempenho em variadas situações, como no caso de exposição ao desgaste erosivo.O presente trabalho estuda os efeitos da erosão por impacto de partículas sólidas em superfícies de amostras de um aço inoxidável duplex UNS S32205, tanto do ponto de vista morfológico quanto do topográfico. Superfícies de amostras polidas e posteriormente submetidas a ataques erosivos com partículas de alumina em fluxo de ar, foram examinadas por microscopia eletrônica de varredura, para verificação das formas de desgaste obtidas, e submetidas a ensaios de rugosidade, para determinação do perfil e avaliação da evolução do processo erosivo. Foi feito um exame mais detalhado de formatos de crateras, para comparação com mecanismos propostos em modelos descritos na literatura e com resultados de simulações pelo método dos elementos finitos. Nesse aspecto, o método utilizado mostrou-se tão eficaz quanto aos métodos tradicionais de estudos balísticos com uma só partícula, além de mais abrangente e econômico. As medidas de rugosidade superficial e as informações estatísticas derivadas sinalizaram a possibilidade de utilização dessa ferramenta para avaliar as condições de efetiva perda de massa, que caracterizam a erosão.
Duplex stainless steels are being increasingly used in applications that require a greater corrosion resistance than traditional stainless steels. Its applications in both, outdoor or submerged structures, motivate the studies on its performance in various situations, as in the case of exposure to erosive wear. This work studies the effects of erosion by impact of solid particles on surfaces of samples of duplex stainless steel UNS S32205, from the point of view of both aspects, morphological and topographycal. Polished surfaces of the samples were subjected to erosive attacks by alumina particles in air flux, with different exposure times. These were examined by scanning electron microscopy, looking at the forms of wear obtained and the surfaces roughnesses were measured, aiming to follow the evolution of the erosive process. It was made a more detailed examination of craters, for comparison with the proposed mechanisms in models described in the literature and with the results of simulations by the finite elements method. In this aspect the method proved to be as effective as the traditional methods of ballistic studies using single particles, as well as to be more comprehensive and economic. The measures of surface roughness and the statistics from the derived data signaled the possibility of use of this tool to evaluate the beginning of the effective loss of mass, which characterizes the erosion.
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Bouzaida, Dalel. "Caractérisation et suivi des états de surfaces éolisés en Tunisie pré-saharienne : approches stationnelle et spatiale." Thesis, Lyon 2, 2012. http://www.theses.fr/2012LYO20016.
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Suite aux changements climatiques, de nouveaux paysages reflétant les interactions entre les processus naturels et les activités humaines inappropriées sont apparus en Tunisie Méridionale. L’érosion éolienne en est l’une des manifestations les plus remarquables. Au cours de cette thèse, une méthodologie opérationnelle et validée (méthode du transect permanent) a été mise au point pour la caractérisation des états de surfaces éolisés et la quantification du bilan sédimentaire d’un transect d’environ 500m de longueur sur une période de deux ans. A l’échelle spatiale, la cartographie des Unités Eoliennes : zones de départ, transit et dépôt de sable a été élaborée. Un essai de caractérisation radiométrique des zones de dépôt ensablées a été ensuite tenté pour l’analyse diachronique des changements survenus durant plus de 35 ans. A l’échelle stationnelle, la méthode du transect permanent permet le calcul diachronique des bilans sédimentaires et la comparaison simultanée des changements des Complexes d’Etat de Surface. La seule observation des états de surface éolisés est insuffisante pour déterminer le fonctionnement éolien précis d’une région, elle induit à des erreurs d’interprétation sur les processus sédimentaires en cours.A l’échelle spatiale, les cartes des Unités Eoliennes permettent de déterminer la vulnérabilité du milieu face aux processus de déflation, transport et dépôt. De plus, la caractérisation des zones ensablées par des indices radiométriques n’est pas évidente avec des images de 30 m de résolution. Les analyses statistiques effectuées ont montré que l’indice de couleur est le plus indiqué pour ce genre d’étude. Le calcul des taux de changement entre deux images de dates successives permet d’estimer l’évolution temporelle des espaces ensablés et la distribution spatiale des zones nouvellement ensablées sur plus de 35 ansUnder the effect of climate change, new landscapes reflecting the interactions between natural processes and human inappropriate activities appeared in Southern Tunisia. Wind erosion is one of the most important events. In this thesis, operational and validated methodology (the permanent transect method) has been developed for the characterization of Surfaces States and quantification of the sediment balance of a 500 m length transect over a period of two years. On spatial scale, mapping of the Aeolian units of deflation, transit and sand deposit was developed. Radiometric characterization of sand accumulations was then tried for the detection of changes that occurred within more than 35 years.At the site level, the permanent transect method enabeled the diachronic sedimentary balance calculation and the comparison of the Surface states changes. The single observation of these areas is insufficient to determine the real eolian process of a region ; moreover it induces to errors of interpretation on the sedimentary process.At the spatial scale, maps of the Aeolian units enabeled to determine the vulnerability of the environment to the process of deflation, transport and deposition. In addition, the characterization of sand accumulations by radiometric indices is not obvious within 30 m resolution images. The statistical analyses have shown that Color Index is the most indicated for this type of study. The calculation of the rates of change between two successive dates images allows to estimate the sandy spaces evolution and their spatial distribution for more than 35 years
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Duncan, S. "Ion erosion in surface analysis." Thesis, Loughborough University, 1985. https://dspace.lboro.ac.uk/2134/28023.
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Low energy ion bombardment is a process used in surface analysis and in the electronics and telecommunications industries. Techniques such as Auger Electron Spectroscopy (AES), X-ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectroscopy (SIMS) employ ion bombardment for surface cleaning and for the provision of composition-depth profiles.
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Wheeler, David William. "Solid particle erosion of CVD diamond coatings." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342748.
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Семко, Петро Володимирович, and Petro Semko. "Дослідження автоматизованої системи підготовки поверхонь деталей до нанесення покриттів." Master's thesis, Тернопільський національний технічний університет ім. І. Пулюя, Факультет прикладних інформаційних технологій та електроінженерії, Кафедра автоматизації технологічних процесів і виробництв, 2019. http://elartu.tntu.edu.ua/handle/lib/29795.
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Робота виконана на кафедрі автоматизації технологічних процесів і виробництв факультету прикладних інформаційних технологій та електроінженерії Тернопільського національного технічного університету імені Івана Пулюя Міністерства освіти і науки України.
Захист відбудеться «26» грудня 2019 р. о 8.00год. на засіданні екзаменаційної комісії №43 у Тернопільському національному технічному університеті імені Івана ПулюяВ даній кваліфікаційній роботі розроблено автоматизовану лінію, для реалізації технологічного процесу підготовки поверхонь деталей до нанесення лакофарбових та гальванічних покриттів. Автоматизована дільниця підготовки поверхонь до нанесення покриття забезпечує наступні технологічні переходи: Очистка поверхонь. В операцію очистки включать наступні операції, - видалення механічних забруднень, обезжирення та видалення хімічних забруднень (окиси, іржа, поверхневі сполуки матеріалу і.т.ін.). Операція очистки проводиться хімічними методами. Пасивування поверхонь. Операція пасивування повинна забезпечити надійність отриманої чистої поверхні, запобігати міжопераційному окисленню перед нанесенням основного покриття деталей. Промивка поверхонь (основна та міжопераційна). Для забезпечення чистоти поверхні від речовин попередніх технологічних переходів. Сушка поверхонь деталей. Видалення залишкової вологи та активних розчинів з поверхні деталей для забезпечення мінімального часу контакту поверхні з вологою, яка сприяє корозії та окисленню матеріалу. Регенерація розчинів. Регенерація активних розчинів їх очистка забезпечить економію витрат речовин, що в результаті збільшить рентабельність її використання. Чистота розчинів впливає на якість проходження хімічних реакцій, скорочує їх тривалість. Міжопераційне транспортування. Для забезпечення транспортування деталей в автоматизованому режимі роботи між позиціями технологічних переходів. В проекті автоматизованої дільниці передбачено загальну систему керування, яка здійснює загальний контроль і управління лінією по основним параметрам.
In this qualification work an automated line has been developed for the implementation of the technological process of preparing the surfaces of parts for the application of paint and electroplating coatings. The automated surface preparation site for coating provides the following technological transitions: Surface cleaning. The cleaning operation will include the following operations - removal of mechanical impurities, degreasing and removal of chemical contaminants (oxides, rust, surface compounds of the material etc.). The cleaning operation is carried out by chemical methods. Passivation of surfaces. The passivation operation must ensure the reliability of the clean surface obtained, and prevent the inter-operative oxidation before the main coating of the parts is applied. Surface washing (basic and inter-operative). To ensure the purity of the surface from the substances of the previous technological transitions. Drying of parts surfaces. Removal of residual moisture and active solutions from the surface of the parts to ensure minimum contact time of the surface with moisture, which promotes corrosion and oxidation of the material. Regeneration of solutions. The regeneration of the active solutions of their purification will save the cost of substances, which as a result will increase the profitability of its use. The purity of the solutions affects the quality of the passage of chemical reactions, reducing their duration. Inter-operative transportation. To ensure the transportation of parts in an automated mode of operation between positions of technological transitions. The design of the automated section provides a common control system that performs general control and line control over the main parameters.
РЕФЕРАТ 3 АBSTRACT 4 ЗМІСТ 5 ВСТУП 9 1. АНАЛІТИЧНА ЧАСТИНА 10 1.1 Підготовка поверхні до нанесення покриття 10 1.2 Методи підготовки поверхні 14 1.3 Хімічні методи 16 1.3.1 Знежирення 16 1.3.2 Знежирення органічними розчинниками. 17 1.3.3 Лужне знежирення. 18 1.3.4 Емульсійне знежирення 24 1.3.5 Контроль і коректування розчинів у ваннах знежирення. 25 1.4 Травлення чорних металів 26 1.5 Механічні методи очистки поверхонь 27 2 НАУКОВО-ДОСЛІДНА ЧАСТИНА 29 2.1 Кавітаційні ефекти й механізми ультразвукового очищення 29 2.2 Виникнення акустичної кавітації в середовищі очищення 32 2.3 Пульсації пухирців у звуковому полі та їх вплив на поверхню очищення 34 3 ТЕХНОЛОГІЧНА ЧАСТИНА 45 ТЕХНОЛОГІЇ ОЧИСТКИ ПОВЕРХОНЬ ВІД ЗАБРУДНЕНЬ ПЕРЕД НАНЕСЕННЯМ ПОКРИТТІВ 45 3.1 Устаткування та процеси підготовки поверхонь деталей до нанесення покриття 45 3.2 Знежирення 46 3.3 Травлення 47 3.4 Створення проміжних покриттів 48 3.4.1 Фосфатування 48 3.4.2Пасивування 48 3.4.3 Хроматування 48 3.4.5 Утилізація олій 49 3.5 Технологія підготовки поверхонь для різних матеріалів 49 3.5.1 Для підготовки сталевої поверхні 49 3.5.2 Для підготовки оцинкованої поверхні. 49 3.5.3 Для підготовки поверхні алюмінію та його сплавів 50 3.6 Приготування розчинів для підготовки поверхонь 51 3.6.1 Знежирення, сполучене знежирення-травлення 51 3.6.2 Розчин для хімічного знежирення "ЕКОМЕТ-003" 51 3.7 Рекомендації з вибору розчинів знежирення 52 4 КОНСТРУКТОРСЬКА ЧАСТИНА 55 4.1 Устаткування для хімічної підготовки поверхні виробів під фарбування 55 4.1.1 Устаткування для підготовки поверхні методом занурення. 55 4.1.2 Устаткування для підготовки поверхні методом струминного обливу. 56 4.1.3 Устаткування для знежирення розчинниками. 62 4.2 Загальні вимоги до лінії підготовки поверхонь деталей для нанесення покриттів 64 4.3 Будова та склад лінії 65 4.4 Будова та принцип дії складових частин лінії. 66 4.5 Розміщення та монтаж лінії 71 4.6 Розробка автоматичної системи керування лінії підготовки поверхонь до нанесення покриття 74 4.7 Розробка та компоновка функціональної схеми автоматичної системи керування лінії 78 4.8 Блок процесорного комплекту. 80 5 СПЕЦІАЛЬНА ЧАСТИНА 85 САПР І РОЗРОБКА ПРОГРАМНОГО ЗАБЕЗПЕЧЕННЯ 85 5.1 Загальні відомості про систему команд КР1816ВЕ51 (МК51) 85 5.2 Група команд пересилання даних 89 5.3 Група команд арифметичних операцій 90 5.4 Група команд логічних операцій 91 5.5 Група команд операцій з бітами 91 5.6 Група команд передачі керування 91 6 ОБГРУНТУВАННЯ ЕКОНОМЧІНОЇ ЕФЕКТИВНОСТІ 94 6.1 Загальні положення по визначенню економічної ефективності. 94 6.2 Розрахунок витрат на виготовлення та використання модернізованої системи управління. 94 6.3 Розрахунок економічного ефекту від виготовлення та експлуатації приладу за розрахунковий період 105 6.4 Розрахунок ефективності капітальних вкладень. 106 7 ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ 108 7.1 ОХОРОНА ПРАЦІ 108 7.1 Правила безпеки при експлуатації обладнання лінії підготовки поверхонь 108 7.2 Заходи забезпечення електробезпечності електроустановки 109 7.2 БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ 113 7.2.1 Розробка заходів які зменшують небезпеку виникнення вибухів і пожеж на дільниці в цеху 113 7.2.2 Оцінка хімічної обстановки на підприємствах, що використовують СДОР в технологічних цілях 115 7.2.3 Поняття про хімічну обстановку на об’єкті та її оцінку 115 7.2.4 Методи оцінки хімічної обстановки на промисловому об’єкті 117 7.2.5 Особливості оцінки хімічної обстановки на хімічно небезпечному об’єкті 118 8 ЕКОЛОГІЯ 122 8.1 Актуальність охорони навколишнього середовища 122 8.2 Основні джерела забруднень гальванічного виробництва та обладнання для їх усунення 123 8.3. Заходи по усуненню шкідливих впливів гальванічного виробництва 128 ВИСНОВОК 131 ПЕРЕЛІК ПОСИЛАНЬ 135 ДОДАТКИ 140
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Enriquez, Adriana Gomez. "Erodibilidade e tensão crítica de cisalhamento no canal de uma estrada não pavimentada situada em um Latossolo Vermelho-Amarelo." Universidade Federal de Viçosa, 2012. http://locus.ufv.br/handle/123456789/3628.
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Previous issue date: 2012-05-23The erosion in unpaved roads associated with the runoff has negative implication in social, economic and environmental development of a region. Therefore the incorporation of techniques for prevention and control of erosion on these roads is important. The techniques developed for this purpose require knowledge of the indices of soil resistance to erosion, principally the soil erodibility and critical shear stress. In this context, the aim of this study was to determine the erodibility and critical shear stress in the channel of an unpaved road implanted in an Oxisol horizons B and C. Study was conducted on an unpaved road in Viçosa-MG, Brazil, where the indices were obtained using a runoff simulator installed on the channel road, which allows to estimate soil loss associated with different shear stress. The results obtained in each test was adjusted using simple linear regression models and, the models identity test proceeded to obtain a representative value of the indices for the study site, and to obtain the confidence interval associated with the erodibility, considering 95% of probability. The erodibility value determined for the horizon B was 0.0044 g cm-2 min-1 Pa-1, and its associated confidence interval with 95% probability was 0.0035 to 0.0053 g cm-2 min-1 Pa-1. The critical shear stress determined for this horizon was 7.61 Pa. The horizon C erodibility value determined was 0.0347 g cm-2 min-1 Pa-1, and its xv associated confidence interval with 95% probability was 0.0288 to 0.0406 g cm-2 min-1 Pa-1. The critical shear stress value for this horizon was 8.16 Pa.
A erosão em estradas não pavimentadas associada ao escoamento superficial interfere negativamente no desenvolvimento social, econômico e ambiental de uma região. Por isso é importante a incorporação de técnicas que visem a prevenção e o controle da erosão nestas estradas. As diferentes técnicas desenvolvidas para este fim requerem o conhecimento dos índices de resistência do solo ao processo erosivo, sendo a erodibilidade e a tensão crítica de cisalhamento os índices de maior importância. Neste sentido, objetivou-se com a realização deste trabalho, determinar a erodibilidade e a tensão crítica de cisalhamento no canal de uma estrada não pavimentada implantada nos horizontes B e C de um Latossolo Vermelho-Amarelo. O estudo foi realizado em uma estrada não pavimentada do município de Viçosa- MG, onde os índices foram obtidos utilizando um método de determinação direta com o uso de um simulador de escoamento instalado no canal da estrada, que permitiu estimar as perdas de solo associadas a diferentes tensões cisalhantes. Aos resultados obtidos em cada teste foi ajustado um modelo de regressão linear simples e, posteriormente, se aplicou a técnica de teste de identidade de modelos, a fim de obter um valor representativo destes índices para o local de estudo, além de obter o intervalo de confiança associado à erodibilidade com um nível de confiança de 95%. O valor de erodibilidade determinado para o horizonte B, foi de 0,0044 g cm-2 min-1 Pa-1, sendo a ele associado um intervalo de confiança com 95% de probabilidade de 0,0035 a 0,0053 g cm-2 min-1 Pa-1. A tensão crítica de cisalhamento determinada para este horizonte foi de 7,61 Pa. Para o horizonte C o valor de erodibilidade determinado foi de 0,0347 g cm-2 min-1 Pa-1, sendo a ele associado um intervalo de confiança com 95% de probabilidade de 0,0288 a 0,0406 g cm-2 min-1 Pa-1. A tensão crítica de cisalhamento determinada para este horizonte foi de 8,16 Pa.
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Menaa, Merouane. "Performance of surface structures subjected to subsurface soil erosion." Mémoire, École de technologie supérieure, 2008. http://espace.etsmtl.ca/148/1/MENAA_Merouane.pdf.
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Plusieurs infrastructures geotechniques (ex. chaussees, dalles, fondations) exercent une
pression a travers leurs surfaces de contact avec le sol. Le dimensionnement de ces
structures suppose un contact parfait tout au long de la vie de service de celles-ci. Par
ailleurs, I'erosion des sols sous-jacents est un mecanisme qui pent contribuer au
developpement de cavites souterraines et par consequent a une perte locale de contact entre
la structure et le sol, caracterisee par un vide sous la structure.
La performance des structures telles que les chaussees en beton, les dalles ainsi que les
trottoirs sujettes a I'erosion souterraine est etudiee experimentalement et numeriquement
dans ce memoire. Les experiences ont ete menees dans un caisson en acier rigide contenant
du sable ou I'erosion souterraine a ete cree artificiellement; le tout supportant une plaque en
acier rigide. Les deformations de la surface ainsi que les pressions de contact a I'interface
plaque-sol ont ete mesurees afin de quantifier les effets de I'erosion souterraine sur les
contraintes developpees dans la structure. L'etude numerique a ete conduite en utilisant un
modele elastoplastique a 2 dimensions. Le modele a ete calibre avec les resultats
experimentaux et divers scenarios ont ete envisages. Des parametres tels que le volume du
sol erode, sa localisation ainsi que les chargements appliques sur la dalle de beton ont ete
varies. Les resultats de cette recherche ont montre que lorsque le vide est centre directement
sous la dalle, les contraintes de traction developpees dans celle-ci augmentent avec la taille
du vide provoquant ainsi la rupture de la dalle. II a egalement ete conclu que lorsque le vide
est excentre, le sol au voisinage de celui-ci est susceptible de subir une rupture avant que
des contraintes de traction excessives ne se developpent dans la fibre la plus tendue de la
dalle en beton.
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Bao, Ruotian. "Effect of Microbial Induced Carbonate Precipitation on Surface Erosion." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1498471342771954.
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Filho, Edison Aparecido Mome. "Quantitative parameterization of soil surface structure with increasing rainfall volumes." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-30092016-095436/.
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The study of soil structure allows inferences on soil behavior. Quantitative parameters are oftentimes required to describe soil structure and the multifractal ones are still underused in soil science. Some studies have shown relations between the multifractal spectrum and both soil surface roughness decay by rainfall and porous system heterogeneity, however, a particular multifractal response to a specific soil behavior is not established yet. Therefore, the objectives of this research were: (i) to establish relations between multifractal parameters and soil structure changes by analyzing both soil surface roughness maps and 2D images from impregnated soil blocks; and (ii) to utilize these parameters to evaluate soil surface degradation by the processes of crusting and sealing. An experiment with simulated rainfall was assembled on a Fine Rhodic Kandiudalf with an intensity of 120 mm h-1 in quadruplicate plots at amounts of 40, 80, and 120 mm, plus a no-rainfall control. The evolution of the surface roughness was evaluated in three scales of measurement: a field microrelief meter (MRM) gathered readings on a fixed grid (10 x 10 mm, 640,000 mm²); a multistripe laser triangulation (MLT) scanner was used in the laboratory in soil blocks, creating a random mesh (0.5 mm of resolution, 5625 mm²); an X-ray tomography (XRT) scanner gathered readings of a soil block on a fixed grid (0.074 x 0.074 mm, 900 mm²). For micromorphometrical analysis, undisturbed soil samples (0.12 x 0.07 x 0.05 m) were impregnated, sliced in blocks and polished. Each block was divided into three layers (0 to 10 mm, 20 to 30 mm and 40 to 50 mm), parallel to surface, and five images (10X magnification, 156.25 μm2 pixel-1) were taken by layer. After segmentation, three representative images were chosen by layer and the pore system was evaluated. Roughness analyzes showed no differences (p > 0.10) between multifractal parameters across rainfall amounts for MRM measurements, while both MLT and XRT could be used to model roughness degradation by rainfall increase. Since the last two scales presented similar results, MLT could replace XRT in such analysis, due to its lower cost and possibility of a larger area coverage. The multifractal behavior of pores changed according to sealing development and depth of measurement, being sensitive to the changes on size distribution and fragmentation degree (number of pores) within each size class. The Hausdorff dimensions at the left side of the spectrum (Lf(α)min, LΔf(α) and D2) showed a linear behavior with increasing rainfall amount, considering both soil surface roughness and area of pores measurements. However, D2 was not different (p > 0.10) along rainfalls for the porosity closer to surface, although parameters D0-D1, D0-D2 and D1-D2 could be used to described the changes in this layer. Was concluded that the multifractal spectrum is sensitive to structure changes caused by rainfall and that it can be used to parameterize both soil surface and pores degradation.O estudo da estrutura do solo permite inferências sobre seu comportamento. Parâmetros quantitativos são comumente utilizados na avaliação da estrutura e os multifractais ainda são subutilizados na ciência do solo. Alguns estudos mostraram relação entre parâmetros multifractais com a diminuição da rugosidade superficial do solo devido à chuva e a heterogeneidade do sistema poroso. No entanto, uma assinatura multifractal relacionada a um comportamento específico do solo ainda não está estabelecida. Portanto, os objetivos desta pesquisa foram: (i) relacionar parâmetros multifractais com mudanças na estrutura do solo por meio da análise de mapas de rugosidade superficial e de imagens 2D provenientes de blocos impregnados de solo; e (ii) utilizar estes parâmetros para identificar as etapas de degradação do solo devido ao selamento e encrostamento superficial. Um experimento com chuva simulada com intensidade de 120 mm h-1 foi montado em uma Nitossolo Vermelho eutroférrico argiloso em parcelas quadruplas onde aplicou-se volumes de 40, 80 e 120 mm, mais um controle sem-chuva. A evolução da rugosidade superficial foi avaliada em três escalas: um rugosímetro de campo (MRM) reuniu leituras numa grade fixa (10 x 10 mm, 640000 mm²); um escâner com triangulação de lasers em multilinhas (MLT) foi usado em laboratório, sobre blocos de solo, criando uma grade aleatório (0,5 mm de resolução, 5625 mm²); um tomógrafo de raios-X (XRT) reuniu leituras de um bloco de solo em uma grade fixa (0,074 x 0,074 mm, de 900 mm²). Para a análise micromorfométrica, amostras de solo indeformado (0,12 x 0,07 x 0,05 m) foram impregnadas, cortadas em blocos, polidas e subdivididas em três camadas (0 a 10 mm, 20 a 30 mm e de 40 a 50 mm), paralelas à superfície, tendo cinco imagens (ampliação de 10x, 156,25 μm2 pixel-1) geradas por camada. Após a segmentação, três imagens foram selecionadas por camada e o sistema poroso foi avaliado. Análises de rugosidade não mostraram diferenças (p > 0.10) entre parâmetros multifractais nas medições da escala MRM, enquanto MLT e XRT puderam ser utilizadas para modelar a degradação da rugosidade com o aumento do volume de chuva. Como essas duas ultimas escalas apresentaram resultados similares, MLT poderia substituir o uso de XRT em tais análises, devido ao seu menor custo e possibilidade de cobrir área mais vasta durante as análises. O comportamento multifractal dos poros mudou de acordo com o desenvolvimento do selamento superficial e da camada avaliada, sendo sensitivo a mudanças no grau de fragmentação (número de poros) dentro de cada classe de tamanho de poros. As dimensões de Hausdorff a esquerda do espectro (Lf(α)min, LΔf(α) and D2) tiveram relação linear com o aumento de volume de chuva para ambas medições de rugosidade superficial do solo e de área de poros. Entretanto, D2 não foi significativo (p > 0.10) entre volumes de chuva para diferenciar a porosidade próxima a superfície, embora os parâmetros D0-D1, D0-D2 e D1-D2 pudessem ser utilizados para descrever mudanças nessa camada. Conclui-se que o espectro multifractal é sensível à mudanças estruturais no solo causadas pela chuva e que pode ser utilizado na parametrização da degradação da rugosidade superficial do solo e da porosidade.
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Zalewsky, Brian J. "Use of the Water Erosion Prediction Project (WEPP) Model to Predict Road Surface Erosion in Mountain Rangeland Areas." DigitalCommons@USU, 1998. https://digitalcommons.usu.edu/etd/3655.
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A significant source of sediment in many watersheds is that associated with the layout, construction, and maintenance of roadways. Much work has been done in more mesic forested environments with little or none in semiarid systems. Acc urate estimation of runoff and sediment yield from native surfaced roads located in semiarid mountainous ecosystems is important to both private and public regulatory agencies. The Watershed Erosion Prediction Project (WEPP) model represents the most current erosion prediction technology. WEPP has been applied to the problems of logging road erosion in more mesic forests but has not been tested or evaluated on roadways located in semiarid mountainous ecosystems.
Six rainfall simulation experiments were conducted to measure runoff and sediment yield off three separate plots located on Tickville Road, located on Camp W.G. Williams, a National Guard Training Center in Utah . These data were compared with runoff and erosion estimates produced by the WEPP model. WEPP cropland and rangeland erodibility equations were used to predict rill erodibility (Kr), interrill erodibility (Ki), and critical shear (TAUc). These were tested for their effectiveness in predicting road erodibilities in these environments. A sensitivity analysis was performed on those parameters that were suspected of having a substantial impact on model output and accuracy.
There was an excellent correlation between predicted and observed total runoff volumes for all simulations (R2= 0.96). The differences were greater than 10% only for plot 2 wet; otherwise, the average difference for all six simulations was 4.9%. When using Kr, K.i , and TAUc as predicted by rangeland methods, predicted sediment yields differed from those measured, on average, by 82%. Predicted sediment yields differed by only 22% compared to calculated sediment yields, when using the cropland erodibility equations to predict Kr, K.i , and TAUc. A sensitivity analysis showed that percent slope, slope length, days since last tillage, and ridge roughness all had a significant impact on WEPP predicted sediment yields. Results show the effectiveness of the WEPP model in predicting runoff and erosion off native surfaced roads in these semiarid mountainous regions.
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Villanueva, Evelyn. "Risk assessment of rock surface spillway erosion using parametric studies." Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-07022007-155027.
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Macgregor, Duncan S. "Surface seepage and sub-surface destructive processes as controls on the distribution of giant oilfields." Thesis, University of Aberdeen, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363645.
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Study of a database of 350 giant oilfields show these to be dynamic short lived phenomena, with a median age of 35 Ma. A third show evidence of post-entrapment destructive processes, particularly erosion, fault leakage and gas flushing. Biodegradation is a destructive process most active during oil entrapment. Re-entrapment of oil released from spilling or breached traps is common. These processes are illustrated with case examples from SE Asia and throughout the world. The main controls on oilfield preservation are post-entrapment tectonism and seal type, with temperature and hydrodynamic regimes being secondary factors. Destructive processes are concentrated in shallow and deep zones and in seepage-prone traps such as compressional anticlines. Such factors strongly influence the distribution of preserved light oilfields, with preservation potential maximised in tectonically quiescent basins with evaporite or thick mudstone seals e.g. the Middle East and the Permian Basin, or in basin centres distant from inverted or uplifted zones e.g. Central Sumatra. More attention is required in prospect and regional evaluations to models involving post-entrapment leakage and re-migration.
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Beyer, Portner Niki. "Erosion des bassins versant [sic] alpins suisses par ruissellement de surface /." [S.l.] : [s.n.], 1998. http://library.epfl.ch/theses/?nr=1815.
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Andermann, Christoff. "Climate, topography and erosion in the Nepal Himalayas." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2012. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-86385.
Full textAbstract:
This thesis deals with the role of precipitation on erosion and landscape formation in the Nepal Himalayas. I investigate all successive steps involved in the erosion process: 1) Starting from the evaluation of precipitation datasets, 2) the transfer of precipitation to river discharge, 3) the mobilization and transport of material out of the mountain range, 4) and finally, erosion constrains over longer time-scales. I show that the dataset derived from the interpolation of rain gauge data performs best in the Himalayas. I demonstrate the importance of an until now unconsidered, major compartment of the Himalayan discharge cycle, which I identify as a fractured basement aquifer, and estimate the snow and ice melt contribution to the Himalayan rivers. Erosion rates calculated from suspended sediment fluxes and cosmogenic nuclide analysis range between 0.1 and 4 mm/yr. The rivers in the Nepal Himalayas are supply limited and the hillslopes as contributing source are transport limited. Last I show that over several thousand years erosion is not related with precipitation, but with reliefCette thèse porte sur le rôle des précipitations sur l’érosion et la formation des reliefs dans l’Himalaya Népalais. J’étudie chaque étape du processus d’érosion : 1) Evaluation des bases de données de précipitations, 2) Transfert des précipitations au débit fluvial, 3) Mobilisation et transport du matériel dans le bassin versant, et enfin 4) Mécanismes d’érosion sur de longues échelles de temps. Je montre que la base de données de précipitations obtenue par interpolation de données pluviométriques est la plus performante pour la région de l\'Himalaya. Je démontre l’importance d’une composante majeure, jusqu’alors ignorée, du cycle de débit de l’Himalaya que j’identifie comme étant les aquifères de sous-sol fracturé, et j’évalue la contribution de la fonte des neiges et glaces aux rivières Himalayennes. Les taux d’érosion calculés à partir des flux de sédiments en suspension et des analyses de nucléides cosmogéniques varient de 0.1 à 4 mm/a. Les rivières au Népal sont limitées par l’apport sédimentaire alors que les versants, en tant que source de sédiments, sont limités par le transport. Enfin, je montre que l’érosion sur des milliers d’années ne dépend des précipitations mais du relief
Die vorliegende Arbeit beschäftigt sich mit der Rolle des Niederschlag bei Erosions- und Oberflächenprozessen im nepalesischen Himalaja. Ich untersuche die Abfolge der Erosionspsozesse im Himalaja: 1) Ausgehend von der Bewertung von Niederschlagsdatensätzen, 2) die Prozesse der Abflussbildung in Flüssen, 3) die Mobilisierung und Transport von Material, 4) und Erosionsraten über längere Zeiträume. Ich zeige, dass interpolierte Niederschlagsdaten die beste Qualität im Himalaya haben. Ich zeige auf, wie wichtig der bislang unberücksichtigt Grundwasserzwischenspeicher für die Abflussbildung im Himalaya ist und schätze den Anteil der Schnee-und Eisschmelze an dem Gesamtabfluss der Flüssen im Himalaja. Erosionsraten die mittels Schwebestofffracht und der Analyse kosmogener Nukluide berechnet wurden, liegen zwischen 0,1 und 4 mm pro Jahr. Der Sedimenttransport in den Flüssen in Nepal ist limitiert durch die Verfügbarkeit von transportierbarem Material, während der Transport und die Mobilisierung auf den Hängen durch die Verfügbarkeit von Wasser limitiert ist. Zudem sind die Erosionsraten über mehrere Jahrhundert nicht von der Niederschlagsverteilung abhängig sondern vom Relief
28
Downward, Kenneth. "Relationships between surface crusts and erosion in the Tabernas Badlands, Almeria, S.E. Spain." Thesis, University of Wolverhampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325975.
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Karagianna, Anthoula. "Changes in the surface chemistry of enamel exposed to acid : a surface study of caries and erosion." Thesis, University of Leeds, 2012. http://etheses.whiterose.ac.uk/3237/.
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Dental caries is a result of acid production by plaque bacteria and manifests with mineral loss and hard tissue dissolution. Dental erosion is the irreversible loss of dental hard tissue caused by acidic agents without bacterial involvement. Numerous techniques have been described for the early detection of dental caries and erosion. However, they all rely on detecting already lost tissue, suggesting that the disease process has been operating for some time. Recent research suggests that uptake of protons from bacterial or dietary acids precedes hard tissue dissolution. The aim of this research project was to examine whether protonation of sound and carious sterile and non-sterile human primary tooth surfaces which have been subjected to acids of known pH occurs and can be detected in vitro and in situ with a simple and clinically applicable technique. A total of 219 human primary tooth surfaces were investigated in vitro. Of these, 110 sound and carious sterile and non-sterile tooth surfaces were examined at baseline and 109 after an acidic challenge. Universal pH indicator solution was used to assess the protonation state of the tooth surfaces. Significantly more tooth surfaces were found protonated after the acidic challenge compared to baseline for all the groups of teeth (p<0.01) with the exception of non-sterile tooth surfaces with caries into dentine (p=0.467). This was probably because the tooth surfaces were already protonated at baseline as a result of the carious process. The in situ study involved five participants and thirty sound enamel slabs. The enamel slabs were obtained from human primary teeth and were incorporated into mandibular removable appliances. The appliances were placed intra-orally for 48 hours to allow plaque accumulation. After removal from the mouth, the enamel slabs were subjected to 10% w/v sucrose rinse. The protonation state of the tooth surface was assessed with universal pH indicator solution. The proportion of protonated tooth surfaces was significantly higher compared to the proportion of non-protonated tooth surfaces (p<0.001). The results of these studies suggest that protonation of human primary tooth surfaces after an acidic challenge occurs and can be detected with a clinically applicable technique both in vitro and in situ. Measuring the degree of protonation can be a novel means to detect tooth surfaces that are at increased risk of caries and erosion at a very early stage before any irreversible change of the hard tissue structure.
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NUNES, Francisco Miquéias Sousa. "Avaliação hidrossedimentologica de uma Bacia sem dados de vazão utilizando o modelo SWAT." Universidade Federal de Campina Grande, 2018. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/382.
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Capes
O crescimento populacional desordenado juntamente com a intensificação das atividades humanas estão acelerando as modificações dos ecossistemas naturais acarretando vários problemas ambientais, em particular , aos recursos hídricos. A necessidade da humanidade por esse recurso vem crescendo de forma rápida e incompatível com a capacidade de recuperação da natureza, causando a escassez e prejuízo na sua qualidade. Além disso, as diversas finalidades para as quais esses recursos são utilizados têm gerado um grande número de conflitos do uso e também degradação qualitativa e quantitativa dos corpos hídricos.No semiárido brasileiro, a situação de escassez hídrica compromete o desenvolvimento econômico e social da região. Assim, torna-se necessário desenvolver ferramentas adequadas para apoiar a tomada de decisão quanto ao uso dos recursos hídricos. Alterações no uso e na ocupação do solo afetam o comportamento do escoamento superficial, e a análise das tendências na vazão dos cursos d’água é importante para o planejamento do uso dos recursos hídricos e do solo. As variações no regime pluviométrico devido às mudanças climáticas também afetam a disponibilidade hídrica nas bacias hidrográficas.Este trabalho tem por objetivomodelar os processos de geração de escoamento superficial, erosão do solo e a recarga potencial subterrânea na bacia do Rio Sucuru a jusante da barragem de Sumé-PB utilizando o modelo SWAT. Foram utilizados dados de precipitação, temperatura, do período de 1994 a 2015, além de mapas de tipos de solo, uso e ocupação do solo com as mudanças observadas no período.Os parâmetros CANMAX, GWQMN, GW_REVAP, ESCO, EPCO e CN foram identificados como os mais influentes sobre o processo de geração de escoamento superficial. O valor do parâmetro GWQMN foi fixado em 2000 mm, pois nenhuma sondagem realizada na bacia indica uma profundidade do solo maior que 2,0 m. Os parâmetros CANMX, ESCO, EPCO e CN se mostraram muito influentes, pois qualquer pequena alteração para mais ou para menos, provocava uma superestimação e/ou subestimação da lâmina escoada, necessitando assim de muitas tentativas antes de obter seus valores finais. Os resultados demosntram a eficiência do modelo SWAT em quantificar e avaliar comparativamente os processos hidrossedimentologicos na região do cariri paraibano. A contribuição deste trabalho se dá pela formulação de uma metodologia para a realização de estudos hidrossedimentologicos em regiões onde não existem dados de escoamento superficial ou de produção de sedimento pela erosão.
Disorganized population growth coupled with the intensification of human activities is accelerating changes in natural ecosystems, leading to a number of environmental problems, in particular water resources. The need of mankind for this resource has been growing rapidly and incompatible with nature's capacity for recovery, causing scarcity and damage in its quality. In addition, the various purposes for which these resources are used have generated a large number of use conflicts and also qualitative and quantitative degradation of water bodies. In the Brazilian semi-arid, the situation of water scarcity compromises the economic and social development of the region. Thus, it is necessary to develop adequate tools to support the decision making regarding the use of water resources. Changes in soil use and occupation affect the behavior of surface runoff, and the analysis of trends in water flow is important for planning the use of water resources and soil. Variations in pluviometric regime due to climate change also affect water availability in river basins. This work aims to model the processes of generation of runoff, soil erosion and potential underground recharge in the Sucuru River basin downstream of the Sumé-PB dam using the SWAT model. Precipitation and temperature data were used from 1994 to 2015, as well as maps of soil types, land use and occupation with changes observed in the period. The parameters CANMAX, GWQMN, GW_REVAP, ESCO, EPCO and CN were identified as the most influential on the process of generation of surface runoff. The value of the GWQMN parameter was set at 2000 mm, since no survey conducted in the basin indicates a soil depth greater than 2.0 m. The parameters CANMX, ESCO, EPCO and CN were very influential, because any small changes for more or less, caused an overestimation and / or underestimation of the drained sheet, thus requiring many attempts before obtaining their final values. The results demonstrate the efficiency of the SWAT model in quantifying and comparing the hydrosedimentological processes in the Paraíba region. The contribution of this work is given by the formulation of a methodology for the realization of hydrosedimentological studies in regions where there is no data of surface runoff or sediment production.
31
Glotzbach, Christoph. "Low-temperature thermochronology from tunnel and surface samples in the Central and Western Alps." [S.l. : s.n.], 2008.
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32
Wong, Stephanie Tomita. "Computer-aided modeling of controlled release through surface erosion with and without microencapsulation." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002206.
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Woodun, Jayashree Khanta. "Surface crusting of soils from the South Downs in relation to soil erosion." Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270498.
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Finke, Manuela. "Studying food-related demineralisation of teeth with atomic force microscopy (AFM) and nanoindentation." Thesis, University of Bristol, 2001. http://hdl.handle.net/1983/8d6de76b-d940-47ad-b0f6-095f56ddf54e.
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35
Andermann, Christoff. "Climate, topography and erosion in the Nepal Himalayas." Doctoral thesis, Rennes 1, 2011. https://tubaf.qucosa.de/id/qucosa%3A22808.
Full textAbstract:
This thesis deals with the role of precipitation on erosion and landscape formation in the Nepal Himalayas. I investigate all successive steps involved in the erosion process: 1) Starting from the evaluation of precipitation datasets, 2) the transfer of precipitation to river discharge, 3) the mobilization and transport of material out of the mountain range, 4) and finally, erosion constrains over longer time-scales. I show that the dataset derived from the interpolation of rain gauge data performs best in the Himalayas. I demonstrate the importance of an until now unconsidered, major compartment of the Himalayan discharge cycle, which I identify as a fractured basement aquifer, and estimate the snow and ice melt contribution to the Himalayan rivers. Erosion rates calculated from suspended sediment fluxes and cosmogenic nuclide analysis range between 0.1 and 4 mm/yr. The rivers in the Nepal Himalayas are supply limited and the hillslopes as contributing source are transport limited. Last I show that over several thousand years erosion is not related with precipitation, but with relief.Cette thèse porte sur le rôle des précipitations sur l’érosion et la formation des reliefs dans l’Himalaya Népalais. J’étudie chaque étape du processus d’érosion : 1) Evaluation des bases de données de précipitations, 2) Transfert des précipitations au débit fluvial, 3) Mobilisation et transport du matériel dans le bassin versant, et enfin 4) Mécanismes d’érosion sur de longues échelles de temps. Je montre que la base de données de précipitations obtenue par interpolation de données pluviométriques est la plus performante pour la région de l\'Himalaya. Je démontre l’importance d’une composante majeure, jusqu’alors ignorée, du cycle de débit de l’Himalaya que j’identifie comme étant les aquifères de sous-sol fracturé, et j’évalue la contribution de la fonte des neiges et glaces aux rivières Himalayennes. Les taux d’érosion calculés à partir des flux de sédiments en suspension et des analyses de nucléides cosmogéniques varient de 0.1 à 4 mm/a. Les rivières au Népal sont limitées par l’apport sédimentaire alors que les versants, en tant que source de sédiments, sont limités par le transport. Enfin, je montre que l’érosion sur des milliers d’années ne dépend des précipitations mais du relief.
Die vorliegende Arbeit beschäftigt sich mit der Rolle des Niederschlag bei Erosions- und Oberflächenprozessen im nepalesischen Himalaja. Ich untersuche die Abfolge der Erosionspsozesse im Himalaja: 1) Ausgehend von der Bewertung von Niederschlagsdatensätzen, 2) die Prozesse der Abflussbildung in Flüssen, 3) die Mobilisierung und Transport von Material, 4) und Erosionsraten über längere Zeiträume. Ich zeige, dass interpolierte Niederschlagsdaten die beste Qualität im Himalaya haben. Ich zeige auf, wie wichtig der bislang unberücksichtigt Grundwasserzwischenspeicher für die Abflussbildung im Himalaya ist und schätze den Anteil der Schnee-und Eisschmelze an dem Gesamtabfluss der Flüssen im Himalaja. Erosionsraten die mittels Schwebestofffracht und der Analyse kosmogener Nukluide berechnet wurden, liegen zwischen 0,1 und 4 mm pro Jahr. Der Sedimenttransport in den Flüssen in Nepal ist limitiert durch die Verfügbarkeit von transportierbarem Material, während der Transport und die Mobilisierung auf den Hängen durch die Verfügbarkeit von Wasser limitiert ist. Zudem sind die Erosionsraten über mehrere Jahrhundert nicht von der Niederschlagsverteilung abhängig sondern vom Relief.
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Кирилів, Ярослав Богданович, Володимир Іванович Кирилів, Богдан Романович Ціж, and Максимів Ольга Володимирівна. "Resistance of surface nanocrystalline and ultrafine-grained structures to wear and cavitation erosion damage." Thesis, LLC «Computer-publishing, information center», Kiev, Ukraine, 2020. http://hdl.handle.net/123456789/6943.
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Kilic, Arif Nesimi 1963. "A multi-region transient erosion model for concrete with time-dependent surface heat flux." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290695.
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A multi-region, transient concrete ablation and decomposition model is developed. The model consists of four regions of concrete containing a thermally affected region, a dry (evaporated and chemically dehydrated) region, and a gas-free (decarboxylated) region with ablated concrete at the melt/concrete interface. Each region has an interface where the latent heat of local decomposition reactions is taken into account as heat sinks due to endothermic characteristics of the reactions. The time dependent temperature profiles, and depth and growth rate of the regions are evaluated by use of the heat balance integral method. Solutions are obtained for surface heat fluxes in forms of constant, e ⁻(λ)ᵗ, t⁻(λ) and -At to analyze various melt cooldown schemes. The erosion front progresses with a constant rate proportional to the surface heat flux in case of constant heat flux, and terminates at a finite erosion depth that is logarithmically proportional to the cooldown rate for surface heat flux in forms of ⁻(λ)ᵗ and t⁻(λ). Sensitivity analyses are performed to investigate the effects of important thermophysical parameters. Larger erosion depth and rate is observed for higher thermal conductivity. Decomposition temperatures are found to be significant in ablation. Model results were compared with previous experiments and models, and determined to be valid and accurate for different types of melt/concrete interaction. The model presented in this study is simple yet very detailed and accurate in simulating the actual molten core/concrete interaction (MCCI) phenomena, and in investigating the concrete reaction to the molten core. It not only can be embodied into the MCCI codes currently being developed, but also can be used to determine the containment integrity, and fission products released into the environment and to the public as a stand alone code.
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García-Atance, Fatjo Gonzalo. "Surface response of ceramics subject to erosive wear." Thesis, Bournemouth University, 2010. http://eprints.bournemouth.ac.uk/17506/.
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Research concerning the surface of technical ceramics is carried out from the viewpoint of their mechanical performance subjected to relevant operating conditions. The selected materials are silicon nitride, zirconia and alumina. They are subjected to cavitation erosion and other wear processes. When polished ceramics are subjected to cavitation, a pseudoplastic deformation pit is discovered, as well as a delayed phase transformation or ageing of the zirconia stored at room temperature. Measured ageing times recorded are of the order of one month. These two discoveries are novel and a full explanation is explored. The creation of cracks that release the slip planes of ceramic grains allowing plastic deformation is proposed to be the main mechanism. In order to understand the relationship of the zirconia surface degradation with its oxides (yttria or magnesia), several material compositions are tested. It is concluded that the delay of phase transformation relies on the existence of partially stabilized tetragonal zirconia regardless of the oxide used to stabilize it. Part of this research consists of understanding the effects of the experimental procedure that is utilised on the behaviour of the material. An unexpected non homogeneous cavitation erosion shape is obtained when an ultrasonic horn of small diameter is used to produce the bubbles. This non homogeneous region, referred to as ring region for this research, affects the erosion pattern of the material and it differs from the typical ones obtained when following the standard test. The acoustic theory does not explain this phenomenon. Therefore, a new approach is followed. This approach consists of using fluid mechanics equations combined with analytical mechanics principles. It is concluded that the location of cavitation clusters fulfils a condition of minimum energy. On the other hand, there are important differences between this experimental set up and the set up suggested by the published standards. These differences are discussed and a criterion for cavitation erosion resistance is developed. The comparison of cavitation resistance of materials is achieved by means of surface loss as criterion instead of volume loss.
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Andermann, Cristoff. "Climate, topography and erosion in the Nepal Himalayas." Phd thesis, Université Rennes 1, 2011. http://tel.archives-ouvertes.fr/tel-00674919.
Full textAbstract:
Cette thèse porte sur le rôle des précipitations sur l'érosion et la formation des reliefs dans l'Himalaya Népalais. J'étudie chaque étape du processus d'érosion : 1) Evaluation des bases de données de précipitations, 2) Transfert des précipitations au débit fluvial, 3) Mobilisation et transport du matériel dans le bassin versant, et enfin 4) Mécanismes d'érosion sur de longues échelles de temps. Je montre que la base de données de précipitations obtenue par interpolation de données pluviométriques est la plus performante pour la région de l'Himalaya. Je démontre l'importance d'une composante majeure, jusqu'alors ignorée, du cycle de débit de l'Himalaya que j'identifie comme étant les aquifères de sous-sol fracturé, et j'évalue la contribution de la fonte des neiges et glaces aux rivières Himalayennes. Les taux d'érosion calculés à partir des flux de sédiments en suspension et des analyses de nucléides cosmogéniques varient de 0.1 à 4 mm/a. Les rivières au Népal sont limitées par l'apport sédimentaire alors que les versants, en tant que source de sédiments, sont limités par le transport. Enfin, je montre que l'érosion sur des milliers d'années ne dépend des précipitations mais du relief.
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King, David. "Sonochemical analysis of the output of ultrasonic dental descalers." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.538276.
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Ultrasonic descalers are used in dentistry to remove calculus and other contaminants from teeth. One mechanism which may assist in the cleaning is cavitation generated in cooling water around the descaler. The spatial distribution of cavitation around three designs of descaler tips and under three load conditions has been observed using sonochemiluminescence from a luminol solution and compared with the vibratory motion of the tips in a water bath, characterised by scanning laser vibrometry. The type of cavitation was confirmed by acoustic emission analysed by a ‘Cavimeter’ supplied by NPL. Surface profilometry and SEM of eroded hydroxyapatite pellets was performed to quantitatively study the erosion caused by a descaler tip in both contact and non-contact modes. Densitometry was used to study the erosion of black ink from a glass microscope slide, and determined that under the majority of conditions, no erosion was demonstrated via cavitation, by descalers operating in non-contact mode, although significant erosion was demonstrated with the tip in contact with the slide.
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Jess, Scott. "Resolving the timing of major erosion events along the West Greenland-Baffin-Bylot continental margins." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=239479.
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Continental passive margins exhibit high elevation topography in many localities across the globe. The source and age of much of this topography remains a subject of great debate within the wider community, with numerous theories being presented, including significant post-rift uplift and isostatically preserved rift anks. Establishing the mechanisms that generate topography and the onshore evolution across passive margins is vital in understanding regional geological histories and their wider development. The passive margins of the NW Atlantic realm exhibit high elevation topography topped with low relief summits. The origin of this topography is debated, with both 3 km of uplift in the post-rift stage and the isostatic preservation of Cretaceous rift anks being suggested within the literature. The work of this thesis aims to resolve this debate by establishing the timing and source of uplift across the region and determining the onshore evolution prior to, during and after rifting with the application of apatite low temperature thermochronology. Contemporary analytical and modelling techniques are utilised to generate thermal histories from across both central West Greenland and SE Baffin Island, helping to de ne how the modern landscape has formed. Results from this work outline an onshore history dominated by uplift in the Cretaceous and exhumation throughout the Cenozoic. Basement samples from SW Greenland exhibit protracted cooling throughout the Mesozoic and Cenozoic, implying low rates of exhumation have been apparent throughout. Within the Nuussuaq Basin, centralWest Greenland, thermal histories display reheating i through the Late Cretaceous/Palaeogene and cooling to present, consistent with events outlined in the basin's stratigraphy and implying uplift of the topography is likely the result of extrusive volcanism and an isostatic response to the unroo ng of the lithosphere. Spatial trends in data and thermal histories across SE Ba n Island imply much of the landscape is shaped by rift ank uplift along its SE coastline, driving exhumation of the region throughout the Cenozoic. Collectively these results suggest the elevated topography of the NW Atlantic realm is the result of rift related uplift in the Cretaceous, magmatism and widespread exhumation throughout the Cenozoic, preserved by isostatic exure. This interpretation of the region's onshore history contributes greatly to our understanding of the NW Atlantic's geological evolution. The results highlight the role of extensional tectonism, exhumation and isostasy in shaping both margin's landscapes and helps to determine the principal characteristics of the wider extensional system and the evolution of the o shore domain. Moreover, these conclusions have a wider relevance to the evolution of passive margins across the North Atlantic, improving our understanding of how topography across other margins, such as of East Greenland, Norway and the UK, has formed.
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Bontrager, Austin. "Estimation of agricultural soil erosion and surface water quality trends in the Cheney Lake watershed." Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/13182.
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Master of ScienceDepartment of Agronomy
Nathan Nelson
Phosphorus and sediment runoff are the primary cause of eutrophication in Cheney Lake, the primary water source for Wichita, Kansas. Best Management Practices (BMPs) such as no-till farming practices and nutrient management can be implemented to reduce phosphorus runoff on high-risk agricultural fields. Past efforts have established BMP use in this watershed, although the effectiveness of these efforts has not been evaluated. The goals of this project were to identify any existing water quality trends in the Cheney Lake watershed, estimate the current distribution of erosion in the watershed, and evaluate the placement of BMPs with regards to field-scale erosion risk. Parametric, multi-linear regression and non-parametric, seasonal Mann-Kendall analyses were used to identify trends in the Total Suspended Solids (TSS) and Total Phosphorus (TP) of grab samples from the North Fork Ninnescah River. A Geographic Information System (GIS) model based on the Revised Universal Soil Loss Equation (RUSLE) was used to estimate watershed-scale erosion, prioritize agricultural land for BMP placement, and evaluate existing placement of BMPs within the Cheney Lake watershed. No detectible trends were identified in the water quality data due to stream variability, frequency of sampling, or absence of actual improvement in water quality. Additional sampling must be done to detect any trends in the future. BMPs were implemented on 13% of prioritized field area, and 11% of non-prioritized field area. Conservation Reserve Program (CRP) fields were placed on 14% of prioritized field area, and 5% of non-prioritized field area. No-till practices were implemented on 13% of prioritized field area, and 18% of non-prioritized field area. The top 20% eroding fields were identified given current conditions, and account for approximately 56% of the watershed-wide erosion. The GIS method has demonstrated utility in evaluating past erosion control measures for the watershed and in informing future decisions concerning BMP placement.
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Alistoun, Judith Robyn. "The origin of endorheic pans on the African erosion surface North of Grahamstown, South Africa." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1011048.
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Pans on the African Erosion Surface near Grahamstown are small features, which, perhaps due to their small size have been neglected by researchers. From the outset the striking difference of these pans relative to other pans in southern Africa, is that the host rock is silcrete, a highly resistant rock well known as being associated with deeply weathered plateaus. The dominant origin theory for pans in southern Africa was developed by Goudie and Thomas (1985), and focuses on mechanisms relating to erosion and deflation. This model does not fit in well with the pans that have formed on substrate that has largely been unaffected by erosion in recent geological history (thousands to 10 000 years). As such this study examined the role of prolonged chemical weathering of Dwyka Tillite, that has led to the formation of silcrete. The hypothesis was that such deep weathering is responsible for local scale volume changes, which have in turn led to the formation of a depression. The centre of the pan indicated the highest concentration of Al₂O₃ and kaolinite at mid depths, and their concentrations decreased vertically away from these depths, and laterally towards the margins of the pan. Similar results were noted for SiO₂, while CaO and MgO (and calcite and dolomite) were highest at mid depths along the margins of the pan, and decreased laterally toward the centre of the pan. Results indicated that there was a positive relationship in the centre of the pan between: - the degree of chemical weathering and volume losses, - relative elevation of the pan and volume changes. Geochemically and mineralogically, there was a link between the high concentrations of Ca and Mg carbonates and volume gains in the margin of the pans. It is proposed that transpiration of vegetation along the margin of the pan caused the lateral movement of solutes, and the selective exclusion of these solutes by plants was associated with carbonate precipitation, leading to the creation of local relief. These results provide evidence to suggest that weathering and precipitation processes occurring over geological time scales are responsible for minor scale relief features, whose origin has been mistakenly attributed to deflation processes occurring over hundreds to thousands of years.
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Santos, Julio Cesar Neves dos. "MensuraÃÃo da erosÃo do solo no semiÃrido em diferentes usos de terras e escalas espaciais." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7299.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoA obtenÃÃo de dados de erosÃo do solo em diferentes escalas espaciais à de fundamental importÃncia, principalmente no semiÃrido do Nordeste brasileiro onde esses dados sÃo escassos. O semiÃrido brasileiro à vulnerÃvel à erosÃo hÃdrica, principalmente devido Ãs suas caracterÃsticas climÃticas, edÃficas e Ãs prÃticas de exploraÃÃes insustentÃveis, resultando no empobrecimento dos solos agrÃcolas e comprometendo a qualidade das Ãguas dos reservatÃrios superficiais (principais reservas hÃdricas da regiÃo). Nesse sentido, o presente estudo objetivou gerar dados bÃsicos de escoamento, produÃÃo de sedimento e analisar os principais processos e fontes de variaÃÃo na perda de solo em diferentes escalas espaciais em regiÃo semiÃrida, bem como os processos naturais atuantes em cada escala, e os efeitos do uso do solo na conservaÃÃo do meio. A Ãrea de estudo està localizada no semiÃrido cearense, na bacia hidrogrÃfica do Alto Jaguaribe no municÃpio de Iguatu, no Centro Sul do Estado do CearÃ. Os estudos de erosÃo e escoamento superficial foram conduzidos em trÃs nÃveis de escala: microbacias com Ãreas em torno de 1 a 3 ha, parcelas de erosÃo de 20 m2 e parcelas de 1 m2, todas sob condiÃÃes de chuvas naturais. Ao todo, foram instaladas quatro microbacias experimentais, seis parcelas de erosÃo de 20 m2 e seis parcelas de 1 m2, sob diferentes usos do solo; Caatinga nativa; Caatinga raleada; desmatamento seguido de enleiramento e cultivo de milho; e desmatamento, queima com cultivo de pastagem. O estudo ocorreu durante os anos de 2009, 2010 e 2011, com chuvas concentradas de janeiro a junho, correspondendo à estaÃÃo chuvosa da regiÃo. As coletas para quantificaÃÃo do volume escoado superficialmente e de amostras para determinaÃÃo da perda de sedimentos foram realizadas a cada evento de chuva erosiva, no acumulado de 24 horas. Ocorreram maiores coeficientes de escoamento e perdas de solo na escala de 20 m que nas escalas de 1 m e de microbacia: em relaÃÃo à escala de 1 mÂ, a parcela de 20 m provoca um aumento da velocidade de escoamento ao longo da vertente, aumentando tambÃm a capacidade de transporte; na escala de microbacia, a presenÃa de Ãreas com baixas declividades atuaram como zonas receptoras de sedimentos. Na Ãrea com cobertura de Caatinga Nativa, a presenÃa de pontos de alta erodibilidade e com solo nu, na escala de microbacia, à responsÃvel pela maior parte das perdas de solo, fato que nÃo pode ser representado na pequena escala de parcela. Jà a Ãrea que recebeu o tratamento de raleamento, apresentou na escala de microbacia menor coeficiente de escoamento superficial e menores perdas de solo em relaÃÃo à Ãrea Caatinga Nativa. O manejo de desmatamento e enleiramento dos restos vegetais e cultivo de milho, proporcionou incremento no coeficiente de escoamento superficial e nas perdas de solo em relaÃÃo ao perÃodo anterior, com cobertura de Caatinga nativa. O tratamento de desmatamento, queimada e cultivo de pastagem (Andropogon gayanus Kunt), resultou nas maiores perdas de solo e Ãgua em relaÃÃo aos demais manejos estudados.
Obtaining data of soil erosion on different spatial scales is of fundamental importance, especially in the semi-arid regions of northeastern Brazil where such data are scarce. The semi-arid region is vulnerable to water erosion, mainly due to its climatic and edaphic characteristics, and the unsustainable land use practices, which result in the impoverishment of agricultural soils, and compromise the water quality of the surface reservoirs (the main water resources of the region). The main goal of this study was generate basic data flow, sediment yield and analyze the main process and sources of variation in soil loss at different scales in semi-arid region. It analyzed the natural process that is operating in each one scale and the land use effects in the conservation of the environment. The study area is located in the semi-arid region of the state of CearÃ, in the watershed of the Upper Jaguaribe in the Iguatu County, in the south central area of the state. Studies of erosion and surface runoff were conducted on three scale levels: watersheds with areas of around 1 to 3 ha, erosion plots of 20 m2, and plots of 1 m2, all under natural-rainfall conditions. In all, four experimental watersheds were installed together with six erosion plots of 20 m2 and six plots of 1m2 with different types of land use; native Caatinga; thinned Caatinga; deforestation followed by bunching and the cultivation of corn, and deforestation, burning and the cultivation of pasture. The study was carried out from 2009 to 2011, with rainfall concentrated in the months of January to June, corresponding to the rainy season in the region. Samples to quantify the volume of surface runoff, and samples to determine sediment loss, were taken for each erosive-rain event in an accumulated period of 24 hours. There were higher runoff coefficients and soil losses on the 20 m2 scale than on the 1 m2 and watershed scales: on the scale of 1 mÂ, the plot of 20 m causes an increase in flow velocity down slopes, also increasing transport capacity; on the scale of the watershed, places with low slopes acted as receiving areas for sediment. In the area with native Caatinga vegetation, the presence of points of high erodibility and of bare soil, on the watershed scale, is responsible for most of the soil loss, a fact that is not present on the small scale of the plots. The area which was thinned out, however, presented a lower runoff coefficient and less soil-loss on the watershed scale, in relation to the area of native Caatinga. After deforestation, bunching of the plant remains, and planting of corn, an increase in the runoff coefficient and soil loss can be seen in relation to the previous period with a coverage of native Caatinga. The treatment of deforestation, burning and the cultivation of pasture (Andropogon gayanus Kunt) resulted in the greatest soil and water losses in relation to the other management strategies studied.
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Lira, Daniely Lidiany Costa. "Assoreamento em densas redes de reservatÃrios: o caso da bacia hidrogrÃfica da barragem Pereira de Miranda, Ce." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8835.
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FundaÃÃo de Amparo à Pesquisa do Estado do CearÃO presente estudo tem como objetivo analisar os impactos da densa rede de reservatÃrios da bacia hidrogrÃfica do aÃude Pereira de Miranda (Pentecoste) na produÃÃo de sedimentos e capacidade de armazenamento hÃdrica do sistema. A bacia estudada localiza-se no Nordeste Brasileiro, no Estado do CearÃ, com uma Ãrea de aproximadamente 3.230 km2. Possui uma precipitaÃÃo mÃdia anual de 854 mm e evaporaÃÃo potencial mÃdia observada em tanque do tipo classe A à de 1.464 mm. O solo e a vegetaÃÃo predominante sÃo do tipo luvissolo e caatinga arbustiva aberta. Imagens de satÃlite de anos Ãmidos foram utilizadas para levantamento da aÃudagem na bacia. Foram identificadas unidades de erosÃo derivadas da sobreposiÃÃo de mapas dos parÃmetros da EquaÃÃo Universal de Perdas do Solo (EUPS), o que permitiu a estimativa da erosÃo localizada na bacia e identificaÃÃo de Ãreas potencialmente produtoras de sedimento. Um modelo simplificado foi utilizado para simular a propagaÃÃo de sedimentos pela densa rede de reservatÃrios da bacia. Para estimativa do assoreamento no reservatÃrio Pereira de Miranda, diferentes cenÃrios de estrutura do sistema foram considerados. Foi estimada uma taxa de erosÃo mÃdia na bacia de 59 t.ha-1.ano-1, sendo que 42% da Ãrea da bacia apresenta grau de erosÃo moderado. De acordo com o modelo, o assoreamento do reservatÃrio Pentecoste pode variar de 1,1 a 2,6% por dÃcada, dependendo do cenÃrio considerado. Observa-se ainda que os reservatÃrios de montante podem reter atà 58% do sedimento que chegaria ao aÃude Pereira de Miranda. Os reservatÃrios muito pequenos, com capacidade de atà 100.000 mÂ, embora representem apenas 1,83% da disponibilidade hÃdrica do sistema, sÃo capazes de reter quase 8% do total de sedimento produzido. AnÃlises de sensibilidade mostram que a capacidade de retenÃÃo de sedimentos nos reservatÃrios de montante pode variar de 20 a 58%, dependendo da estrutura do sistema quanto à existÃncia de reservatÃrios de diferentes classes de tamanho. Constata-se ainda que a taxa de reduÃÃo da capacidade de armazenamento hÃdrica do sistema em funÃÃo do assoreamento dos reservatÃrios de montante à relativamente maior do que a observada para o aÃude Pereira de Miranda, devido à retenÃÃo de sedimentos a montante.
The present study aims at analyzing the impacts of the dense reservoir network of the Pereira de Miranda catchment in its sediment yield and water storage capacity of the system. The studied area is located in the Brazilian Semiarid region, in the State of CearÃ, with an area of approximately 3230 km2. It has an average annual rainfall of 854 mm and an annual potential evaporation of 1464 mm. The predominant soil and vegetation type are luvissolo and open shrub caatinga. Satellite imageries from wet years were used to identify the reservoirs of the catchment. Erosion units were identified derived from map overlay of the parameters of the Universal Soil Loss Equation (USLE), which enables the estimation of sediment yield and the identification of areas with high sediment production. A simplified model was used to simulate the sediment routing through the dense reservoir network of the basin. For the estimation of sedimentation at the Pereira de Miranda Reservoir, different scenarios of the system structure were considered. A mean erosion rate of 59 t.ha-1.year-1 was estimated for the basin, in which 42% of the basin area presents a moderate degree of erosion. According to the model, silting of the Pereira de Miranda reservoir may vary from 1.1 to 2.6 %.decade-1, depending on the scenario considered. One may observe that upstream reservoirs are able to retain until 58% of the sediments that would reach the Pereira de Miranda reservoir. The very small reservoirs, with storage capacity below 100,000 mÂ, are able to retain almost 8% of the generated sediments, although they represent just 1.83% of the system water storage capacity. Sensitivity analysis shows that the sediment retention capacity of the upstream reservoirs may vary from 20 to 58%, depending on the system structure concerning the presence of upstream reservoirs from different size classes. One may still conclude that the reduction rate of water storage capacity at the system as a function of reservoir siltation is relatively larger then that observed for the Pereira de Miranda reservoir, due to the upstream sediment retention.
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Mounirou, Lawani A. "Etude du ruissellement et de l’érosion à différentes échelles spatiales sur le bassin versant de Tougou en zone sahélienne du Burkina Faso : quantification et transposition des données." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20039/document.
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La variabilité spatio-temporelle du ruissellement et de l'érosion hydrique n'est pas un fait nouveau. Leurs caractéristiques s'estiment généralement avec une marge raisonnable sur des parcelles d'un à quelques dizaines de m². Avec l'accroissement de la surface, l'hétérogénéité du milieu croît ce qui induit un effet d'échelle. Le passage de la parcelle au bassin versant n'est pas totalement maîtrisé compte tenu de la complexité et de la variabilité des facteurs mis en jeu. L'objectif de cette thèse est de comprendre les processus de ruissellement et de l'érosion dans différents environnements et à différentes échelles spatiales, d'identifier les sources de variation, puis de développer une méthodologie de transposition des résultats de l'échelle parcellaire à l'exutoire du bassin versant. À cet effet, un réseau de dix-huit parcelles expérimentales de différentes tailles, de deux unités hydrologiques ont permis de quantifier le ruissellement et les pertes en terre sur les principaux états de surface du bassin versant de Tougou.Les résultats obtenus sur les micro-parcelles de 1m², les parcelles de 50 et 150m², les unités hydrologiques de 6 et 34 ha et le bassin versant de 37km², montrent que, tant sur sols cultivés que sur sols dénudés, la lame ruisselée ainsi que les pertes en terres diminuent lorsque la superficie augmente, pour une même pluie et dans des conditions comparables d'humidité préalable des sols. Ce phénomène d'effet d'échelle de la superficie sur l'écoulement et l'érosion est connu des hydrologues qui se heurtent toujours à l'écueil de l'extrapolation des résultats obtenus sur petites superficies à des superficies plus grandes. Nos résultats montrent que l'effet d'échelle observé sur le ruissellement et l'érosion est dû principalement à l'hétérogénéité spatiale des sols (propriétés hydrodynamiques, microrelief) et à sa variabilité (état des variables) et que la dynamique temporelle de l'intensité de la pluie ne fait que l'amplifier.Les résultats obtenus lors des essais de transposition permettent de soutenir avec raison qu'une meilleure extrapolation des données de l'échelle parcellaire à l'échelle du bassin viendra de la prise en compte des questions de la connectivité hydrologique.En définitive, cette étude met en avant l'intérêt d'effectuer des mesures de ruissellement et d'érosion sur des unités homogènes en termes d'occupation du sol qui peuvent représenter une mosaïque hétérogène de surfaces homogènes. La localisation sur le bassin versant et le taux de connectivité de ces unités hydrologiques à l'intérieur desquelles les processus dominants du ruissellement et d'érosion se manifestent peuvent permettre d'approcher la résolution du problème de transfert d'échelleThe spatio-temporal variability of runoff and erosion is not new fact. Their characteristics are generally estimated with a reasonable margin on plots of a few tens of square meters. With the increase of the surface, the heterogeneity of environment increases which induces a scale effect. The passage of the plot to the catchment is not totally controlled because of the complexity and variability of factors come into play. The objective of this thesis is to understand the processes of runoff and erosion in different environments and at different spatial scales, to identify the sources of variation, and to develop a methodology for implementation of the results of field scale to the basin outlet. To this end, a network of eighteen plots of different sizes, two hydrological units were used to quantify runoff and soil loss on the main surface features Watershed Tougou.The results obtained on micro-plots of 1 m², plots of 50 and 150 m², hydrologic units of 6 and 34 ha and the catchment area of 37 km², show that, both in cultivated soils and on bare soils, the runoff excess decreases as the area increases, for the same rain and prior comparable humidity conditions of the soil. This phenomenon of the scale effect of the area on runoff is known to hydrologists who still face the challenge of extrapolating results obtained on small areas to larger areas. Our results show that the scale effect observed on the runoff is mainly due to the spatial heterogeneity of soils (hydraulic properties, microrelief) and its variability (state of the variables) and that temporal dynamics of the intensity of rain just amplifies it. The results obtained in tests of transposition can maintain with reason that a better extrapolation of data from the field scale across the pond comes from the consideration of the issues of hydrologic connectivity.Ultimately, this study highlights the value of measurements of runoff on homogeneous units in terms of land use that may represent a heterogeneous mosaic of homogeneous areas. The location on the watershed and the rate of connectivity of the hydrologic units within which the dominant processes of runoff occur can allow approach the solution of the problem of scale transfer
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Kuhnert, Matthias. "Quantifizierung von Oberflächenabfluss und Erosion auf Böden mit hydrophoben Eigenschaften." Phd thesis, Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2009/3287/.
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Die Zielsetzung der vorliegenden Arbeit ist die Beschreibung hydrophober Bodeneigenschaften und deren Auswirkungen auf Oberflächenabfluss und Erosion auf verschiedenen Skalen. Die dazu durchgeführten Untersuchungen fanden auf einer Rekultivierungsfläche im Braunkohlegebiet Welzow Süd (Südostdeutschland) statt. Die Prozesse wurden auf drei Skalen untersucht, die von der Plotskala (1m²) über die Hangskala (300m²) bis zur Betrachtung eines kleinen Einzugsgebietes (4ha) reichen. Der Grad der hydrophoben Bodeneigenschaften wurde sowohl direkt, über die Bestimmung des Kontaktwinkel, als auch indirekt, über die Bestimmung der Persistenz, ermittelt. Dabei zeigte sich, dass der Boden im Winterhalbjahr hydrophil reagierte, während er im Sommerhalbjahr hydrophobe Bodeneigenschaften aufwies. Die Ergebnisse deuten darauf hin, dass ansteigende Bodenwassergehalte, die in der Literatur häufig als Ursache für einen Wechsel der Bodeneigenschaften angegeben werden, auf dieser Fläche nicht zu einem Umbruch der Bodenbedingungen führen. Stattdessen kam es als Folge des Auftauens von gefrorenem Boden zu hydrophilen Bodeneigenschaften, die zu einem Anstieg des Bodenwassergehalts führten. Räumliche Unterschiede zeigten sich in den geomorphologischen Einheiten. Rinnen und Rillen wiesen seltener hydrophobe Eigenschaften als die Zwischenrillenbereiche und Kuppen auf. Diese räumlichen und zeitlichen Variabilitäten wirkten sich auch auf den Oberflächenabfluss aus, der als Abflussbeiwert (ABW: Quotient aus Abfluss und Niederschlag) untersucht wurde. Der ABW liegt auf Böden mit hydrophoben Bodeneigenschaften (ABW=0,8) deutlich höher als bei jenen mit hydrophilen Eigenschaften(ABW=0,2), wie sie im Winter oder auf anderem Substrat vorzufinden sind (diese Werte beziehen sich auf die Plotskala). Betrachtet man die Auswirkungen auf unterschiedlichen Skalen, nimmt der Abflussbeiwert mit zunehmender Flächengröße ab (ABW = 0,8 auf der Plotskala, ABW = 0,5 auf der Hangskala und ABW = 0,2 im gesamten Gebiet), was in den hydrophil reagierenden Rillen und Rinnen auf der Hangskala und dem hydrophilen Substrat im Einzugsgebiet begründet ist. Zur Messung der Erosion wurden verschiedene, zum Teil neu entwickelte Methoden eingesetzt, um eine hohe zeitliche und räumliche Auflösung zu erreichen. Bei einer neu entwickelten Methode wird der Sedimentaustrag ereignisbezogen über eine Waage bestimmt. In Kombination mit einer Kippwaage ermöglicht sie die gleichzeitige Messung des Oberflächenabflusses. Die Messapparatur wurde für Gebiete entwickelt, die eine überwiegend grobsandige Textur aufweisen und nur geringe Mengen Ton und Schluff enthalten. Zusätzlich wurden zwei Lasersysteme zur Messung der räumlichen Verteilung der Erosion eingesetzt. Für die erste Methode wurde ein punktuell messender Laser in einer fest installierten Apparatur über die Fläche bewegt und punktuell Höhenunterschiede in einem festen Raster bestimmt. Durch Interpolation konnten Bereiche mit Sedimentabtrag von Akkumulationsbereiche unterschieden werden. Mit dieser Methode können auch größere Flächen vermessen werden (hier 16 m²), allerdings weisen die Messungen in den Übergangsbereichen von Rinne zu Zwischenrille große Fehler auf. Bei der zweiten Methode wird mit einer Messung ein Quadratmeter mit einer hohen räumlichen Auflösung komplett erfasst. Um ein dreidimensionales Bild zu erstellen, müssen insgesamt vier Aufnahmen von jeweils unterschiedlichen Seiten aufgenommen werden. So lassen sich Abtrag und Akkumulation sehr genau bestimmen, allerdings ist die Messung relativ aufwendig und erfasst nur eine kleine Fläche. Zusätzlich wurde der Sedimentaustrag noch auf der Plotskala erfasst. Die Messungen zeigen, korrespondierend zu den Bodeneigenschaften, große Sedimentausträge während des Sommerhalbjahrs und kaum Austräge im Winter. Weiterhin belegen die Ergebnisse eine größere Bedeutung der Rillenerosion gegenüber der Zwischenrillenerosion für Niederschlagsereignisse hoher Intensität (>25 mm/h in einem zehnminütigem Intervall). Im Gegensatz dazu dominierte die Zwischenrillenerosion bei Ereignissen geringerer Intensität (<20 mm/h in einem zehnminütigem Intervall), wobei mindestens 9 mm Niederschlag in einer Intensität von mindesten 3,6 mm/h nötig sind, damit es zur Erosion kommt. Basierend auf den gemessenen Abflüssen und Sedimentausträgen wurden Regressiongleichungen abgeleitet, die eine Berechnung dieser beiden Prozesse für die untersuchte Fläche ermöglichen. Während die Menge an Oberflächenabfluss einen starken Zusammenhang zu der Menge an gefallenem Niederschlag zeigt (r² = 0,9), ist die Berechnung des ausgetragenen Sedimentes eher ungenau (r² = 0,7). Zusammenfassend beschreibt die Arbeit Einflüsse hydrophober Bodeneigenschaften auf verschiedenen Skalen und arbeitet die Auswirkungen, die vor allem auf der kleinen Skala von großer Bedeutung sind, heraus.The objective of the thesis is the investigation of water repellent soil conditions and their consequences on surface runoff and erosion by water on different scales. The test site is a lignite mining area situated in Welzow Süd (south east Germany). The processes are to investigate on three different scales, starting with a plot scale (1 m²), then a hill slope scale (300 m²) and, finally, with a small catchment area (4 ha). The level of water repellency was quantified by both direct (contact angle) and indirect measurement (persistence of the soil). The results show seasonal differences with hydrophilic soil conditions during winter and water repellent reactions during summer. For this change in soil conditions, the soil water content is pronounced in literature to be the most important factor. On the test site, the soil water content changed instead as a consequence of the thawing of the soil which affects the hydrophilic conditions of the soil itself. The spatial differences of the soil water content are related to rill and channel areas (hydrophillic) and to knoll areas (water repellent). Both the spatial as well as the temporal variation of the soil conditions affect surface runoff which is investigated as a runoff coefficient (RC: ratio of amount of surface runoff to amount of precipitation). The RC shows higher values on soil with water repellent conditions (RC=0.8) in comparison with the values on hydrophilic soils (RC=0.2). The hydrophilic conditions predominate in areas with different substrates and during the winter. Observations on different scales show a decreasing RC as the size of the area increases (RC = 0.8 on the plot scale, RC = 0.5 on the hill slope scale and RC = 0.2 for the entire catchment area). The reasons for this are the hydrophilic rill in the hill slope area and the hydrophilic substrate in the entire catchment area. The measurement of erosion, based on different methods, some of them just newly developed, quantifies in a good resolution sediment transport spatially as well as temporally. The central part of one of the newly developed approaches is a balance which quantifies an event based sediment output. This approach is coupled with a tipping bucket to measure surface runoff. The system has been developed for coarse textured areas with little amounts of sand and silt. Additionally, two laser systems are used to detect changes in the soil surface over the spatial distribution. The first method contains a laser which measures only a single point and has to be moved in a fixed apparatus above the soil surface in a well defined raster. The areas of sediment abrasion and the detachment areas are restricted by interpolation of the measurement results. This method enables measurements on large areas (16 m² in this project), but tends to result in a high level of errors in the transition zone between rill and interrill. The second laser system covered an area of 1 m² in high resolution. To construct a three-dimensional picture, four different pictures have to be taken from four different directions. This defines the abrasion and detachment areas in a very detailed manner, but the method is very time-consuming and covers only a small area. In addition, measurements on the plots collected the amount of sediment output on a small scale. These results show, corresponding to the water repellent soil conditions, high rates of sediment output during summer, but low rates during winter season. The results show also the dominance of rill erosion in comparison with interrill erosion during high intensity rainfall events (>25 mm/h during one interval of ten minutes). On the contrary, interrill erosion becomes more important during low intensity rainfall events (<20 mm/h during at one interval of ten minutes). At least a 9 mm amount of precipitation with a minimum intensity of 3.6 mm/h is necessary to provoke erosion on this test site. Based on the measurement results regression empirical equations were developed to quantify surface runoff and sediment output. While, surface runoff correlates well with the amount of precipitation (r² = 0,9), sediment output shows little correlation to the amount and intensity of the precipitation (r² = 0,7). In summary, the thesis described effects of water repellent soil conditions on surface runoff and erosion on different scales. The effects on the smaller scales especially are of high interest to hydrological processes.
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Albright, Amy N. "An Analysis of Slope Erosion and Surface Changes on Off-Road Vehicle Trails in Southeastern Ohio." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1276715617.
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Devauchelle, Olivier. "Ecoulements de surface et érosion." Paris 6, 2007. https://hal.archives-ouvertes.fr/tel-01499527.
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L'écoulement laminaire d'un liquide sur un lit granulaire conduit à la formation de divers motifs d'érosion (bancs, méandres, tresses et rides) rencontrés en Géomorphologie fluviale, où les écoulements sont turbulents. En se fondant sur des modèles simples (équations de Saint-Venant, transport par charriage), la présente étude aborde ces systèmes par des méthodes analytiques et numériques. Un modèle de berges érodables est établi pour des micro-rivières. L'étude de leur stabilité éclaire différents phénomènes pour lesquels l'influence des conditions aux bords est cruciale. L'évolution non-linéaire de l'instabilité de banc conduit à l'apparition de fronts d'érosion en forme de chevrons. Le développement des rides est succinctement abordé. Enfin, la théorie de la lubrification est mise en oeuvre pour établir l'existence d'une ligne de contact mobile sur un solide poreux extrait d'un liquide, et sa disparition au profit d'un film de Landau-Levich-Derjagin, au-delà d'une vitesse critique.
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Casas-Apayco, Leslie, Vanessa Manzini Dreibi, Ana Carolina Hipólito, Márcia Sirlene Zardin Graeff, Daniela Rios, Ana Carolina Magalhaes, Marília Afonso Rabelo Buzalaf, and Linda Wang. "Erosive cola-based drinks affect the bonding to enamel surface: an in vitro study." Faculdade De Odontologia De Bauru - USP, 2014. http://hdl.handle.net/10757/324186.
Full textAbstract:
Objective: This study aimed to assess the impact of in vitro erosion provoked by different cola-based drinks (Coke types), associated or not with toothbrushing, to bonding to enamel. Material and methods: Forty-six bovine enamel specimens were prepared and randomly assigned into seven groups (N=8): C- Control (neither eroded nor abraded), ERO-RC: 3x/1-minute immersion in Regular Coke (RC), ERO-LC: 3x/1-minute immersion in Light Coke (LC), ERO-ZC: 3x/1-minute immersion in Zero Coke (ZC) and three other eroded groups, subsequently abraded for 1-minute toothbrushing (EROAB-RC, EROAB-LC and EROAB-ZC, respectively). After challenges, they were stored overnight in artificial saliva for a total of 24 hours and restored with Adper Single Bond 2/Filtek Z350. Buildup coronal surfaces were cut in 1 mm2-specimens and subjected to a microtensile test. Data were statistically analyzed by two-way ANOVA/Bonferroni tests (a=0.05). Failure modes were assessed by optical microscopy (X40). The Interface of the restorations were observed using Confocal Laser Scanning Microscopy (CLSM). Results: All tested cola-based drinks significantly reduced the bond strength, which was also observed in the analyses of interfaces. Toothbrushing did not have any impact on the bond strength. CLSM showed that except for Zero Coke, all eroded specimens resulted in irregular hybrid layer formation. Conclusions: All cola-based drinks reduced the bond strength. Different patterns of hybrid layers were obtained revealing their impact, except for ZC.This study was supported in part by grants given by the São Paulo Research Foundation (FAPESP), Process no. 2009/14986-0, and the National Council for Scientific and Technological Development (CNPq), Process no. 480038/2007-4. In Addition, this study was performed by V.D.M. and A.C.H. as fulfillment of their graduation research, which was supported by FAPESP (Processes no. 2009/01376-9 and 2009/01377-5, respectively). The authors are also grateful to Oral B and SDI, which donated the materials used in the study.
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