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Åsen, Kristina, e Anna Boking. "Dental erosion : kolsyrade vattens erosiva potential". Thesis, Kristianstad University College, School of Health and Society, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hkr:diva-5272.
Testo completoAbstract (sommario):
Syftet med studien var att undersöka den erosiva potentialen av vanligt förekommande kolsyrade vatten med eller utan smaksättning. Studien genomfördes som en laboratoriestudie vid Institutionen för Odontologi vid Göteborgs universitet. Totalt omfattades studien av 34 buteljerade kolsyrade vatten med eller utan smak, tre kolsyrade vatten producerade i kolsyreapparat samt sex referensdrycker. Samtliga produkter testades genom registrering av initialt pH med pH-elektrod och buffring med 0,1 M NaOH till det värde då pH neutraliserats. Dryckens surhetsgrad beräknades därefter vilket anses som ett mått på dess erosiva potential. Resultatet visade att majoriteten av kolsyrade vatten hade ett initialt pH-värde >5 men variationer fanns mellan varumärken. Samtliga studerade vatten uppvisade en lägre erosiv potential jämfört med referensdrycker som färskpressad citron- och apelsinjuice, men inte jämfört med läskedrycker. Data visade att syrakoncentrationen steg när mängden kolsyra ökade. Olika smaktillsatser hade endast en mindre påverkan på den erosiva potentialen. Denna studie visade att kolsyremängden var av större betydelse än smaktillsats för syrakoncentrationen i vattnet.
The aim of this study was to investigate the erosive potential of the most commonly used carbonated waters with or without flavouring. The study was preformed as an in vitro study at the Institution of Odontology at University of Gothenburg. The study was comprised by 34 bottled carbonated waters with or without flavouring, three carbonated waters produced in a carbonator machine and six control drinks. Products were tested and pH was measured using a pH electrode and buffered gradually with 0,1 M NaOH until pH reached neutral value. Calculation of the acidity of the drinks, which is a grade on its erosive potential, was measured. The results showed that a majority of the studied carbonated waters had a pH baseline value >5, but variations existed among the different labels. All of the studied waters showed a lower erosive potential compared with the control products freshly squeezed lemon- and orangejuice, but compared to soft drinks. Data showed that the acid concentration gradually arouse when carbondioxide was added to the water. Different flavouring had only a slight influence on the erosive potential. This study showed that adding carbondioxide was of larger importance than adding flavouring for the acid concentration in the water.
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Giovanini, Junior Nelson. "Análise e aplicação de metodologias de predição de processos erosivos utilizando SIG na Bacia Hidrográfica do Córrego do Engano, Nova Canaã Paulista - SP /". Ilha Solteira, 2019. http://hdl.handle.net/11449/181272.
Testo completoAbstract (sommario):
Orientador: César Gustavo da Rocha LimaResumo: A bacia hidrográfica é uma unidade geomorfológica que agrega os impactos das interferências antrópicas e naturais sobre os recursos hídricos. Mudanças significativas nas características de uma bacia, causadas por processos naturais ou atividades antrópicas, podem gerar alterações, efeitos e impactos na estabilidade biótica e abiótica do sistema, desencadeando desequilíbrios ambientais e, portanto, a degradação da paisagem. Dentre os processos causadores dessa degradação, destaca-se a erosão dos solos. A erosão é um processo geológico responsável pela remoção e pelo transporte de partículas do solo, principalmente pela ação da água das chuvas sendo um importante agente na modelagem da paisagem terrestre e na redistribuição de energia no interior da bacia hidrográfica. Neste trabalho será analisada a relação entre algumas metodologias – e suas modificações - de predição de ocorrência de processos erosivos na Bacia Hidrográfica do Córrego do Engano utilizando um ambiente de Sistemas de Informações Geográficas. Foram aplicados três diferentes métodos: Vulnerabilidade Natural à Erosão (VNE), Equação Universal de Perda de Solos (USLE) e processo de análise hierárquica (AHP). Para a aplicação dos três métodos foi utilizado um Sistema de Informação Geográfica com a criação de um banco de dados com diversas informações necessárias para a aplicação dos métodos, como: mapa de precipitação, erosividade, tipos de solo, erodibilidade, tipos de rochas, fatores topográficos e uso e ocupação.... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The drainage basin is a geomorphological unit that aggregates the protection of anthropic and natural interferences on water resources. Changes in the characteristics of a basin, caused by natural processes or anthropic activities, can generate changes, effects and stability in the biology and in the abiotic system, triggering environmental imbalances and, therefore, a degradation of the landscape. Among the processes that causes this degradation, there is soil erosion. Erosion is a geological process responsible for the removal and transport of soil particles, mainly by the action of rainwater, being an important agent in the modeling of the terrestrial landscape and in the redistribution of energy within a drainage basin. This work will analyze the relationship between some methodologies - and their modifications - of predicting the occurrence of erosive processes in the Corrego do Engano drainage basin using a Geographic Information Systems environment. Three different methods were applied: Natural Erosion Vulnerability (VNE), Universal Soil Loss Equation (USLE) and hierarchical analysis process (AHP). For the application of the three methods was used a Geographic Information System with the creation of a database with several information needed to work with these methods, such as: precipitation map, erosivity, soil types, erodibility, types of rocks, factors topography and land use. For each methodology was determined the probability of occurrence of erosive processes bas... (Complete abstract click electronic access below)
Mestre
3
Hamlin, Lauren Kearns. "Erosion". The University of Montana, 2009. http://etd.lib.umt.edu/theses/available/etd-05282009-130629/.
Testo completo
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Lönnborg, Pernilla. "Erosion". Thesis, KTH, Arkitektur, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168677.
Testo completoAbstract (sommario):
Byggnader är under ständig förändring. Den omkringliggande miljön orsakar en nedbrytning i form av vittring. Material som bryts ner. Vi vet att en byggnad inte kommer att finns för alltid så vad händer om vi låter nedbrytningen vara en tillgång. Naturens processer ger oss perspektiv på tid. Årstider som följer varandra. Berg som eroderar och formeras. Hur kan man förstärka upplevelsen av tid och rum genom en byggnad som tillåts interagera med den omkringliggande miljön och vara under ständig förändring?Buildings are constantly changing. The surrounding environment partly causes a breakdown through weathering. Materials that breaks down. We know that a building won’t stand forever so what happens if we turn the decomposition to an asset? The process of nature gives us perspective of time. Seasons that follows each other. Rocks that erodes and forms. How can we enhance the experience of time through a building that allows integrating with the surrounding environment and being in constant change?
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Slotte, Mikael. "Erosion". Thesis, KTH, Arkitektur, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146183.
Testo completoAbstract (sommario):
Rosenlunds sandbankar är ett naturskyddsområde mellan Jönköping och Huskvarna som rasar med ungefär 30 cm per år. Platsen tillåts att årligen krympa men inte att användas. Det görs inga större ansatser för att dokumentera den för framtida generationer eller synliggöra den för nu levande generationer. I detta examensarbete undersöks ett naturligt fenomen som kommer att påverka civilisationer i tusentals år. Examensarbetet syftar i första hand till att återintroducera en bortglömd plats och beskriva hur den förändras i tid och rum. Med hjälp av studier om erosion, landhöjning, istid och med hjälp av fältstudier tolkas platsens förgänglighet i fotografier och i en serie ritningar. Därefter föreslås ett promenadstråk där det direkt går att beskåda de geologiska processer som omformar platsen. Stråket knyts ihop över tre terränger – sandbank, strandkant och sjö. Den enkla konstruktionen består av balkar och trädäck som placeras på träpålar och gabioner. Konstruktionens livstid är i ett idealfall detsamma som platsens – pelare kommer att ruttna, delar av platsen kommer att växa igen och i ett längre tidsperspektiv kommer branten att flackas ut. Under hela konstruktionens livstid kommer den att kunna användas för att tolka de processer som pågår på platsen och spegla platsens unika förgänglighet.Rosenlunds sandbankar is a nature reserve between Jönköping and Huskvarna eroding about 30 cm per year. It is allowed to annually shrink but not to be used. There are no major attempts to document it for future generations or to make it visible for the present. This thesis examines a natural phenomenon that will affect civilizations for thousands of years. The work is primarily aimed at reintroducing a forgotten site and describe how it changes in time and space. Using studies of erosion, land uplift, ice age and with the help of field studies the site's transformation is interpreted in photographs and a series of drawings. I propose a promenade where the geological processes that transform the site can be observed and followed. The footpath connects three terrains - sand bluff, shore and lake. The structure consists of beams and decking placed on wooden piles and gabions. In an ideal case it will exist as long as the site itself. Pillars will rot, parts of the site will be overgrown, and in the longer term, the slope will flatten out. During its life span, the structure can be used to interpret the processes and reflect the site's unique transience.
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Dotson, Matthew. "Erosion". Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/490.
Testo completoAbstract (sommario):
In my work I am often drawn to relatively simple systems that unfold before the listener. In Erosion, there are several of these processes which unfold simultaneously. The piece begins with a pitch cluster that gradually spreads into total chromatic saturation (about half-way through the piece) before shrinking back into clusters. As this is happening there is, on a macro level, a gradual speeding of events throughout the entire duration of the work. The interactions between this linear progression in the time domain and the (relatively) cyclical progression in the frequency domain form the main dialogue of the work.
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Garcia-Chevesich, Pablo Andres. "Erosion Processes and Control". Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195844.
Testo completoAbstract (sommario):
This dissertation represents a unique contribution to the Spanish literature of soil erosion. The author of this document has written and published "Procesos y control de la erosion", a textbook about the engineering of soil erosion processes and the design of the most up-to-date methods and products used for erosion control. The text has been presented in Appendix A.Besides the above, the author of this dissertation is an active committee member at the International Erosion Control Association (IECA), specifically the International Development and the SOIL Fund programs. IECA members are drawn from individuals and erosion control business of different sizes. However, there was a lack of knowledge within IECA members about the formation of post-fire water repellent layers. For instance, Appendix B is represented by an article written by the author of this document, published in Environmental Connection (Volume 2, Issue 3), on July of 2008. The article gives a general description of what post-fire water repellency is, how is it formed, what factors affect it, its consequences on soil erosion, and how to control soil erosion on an efficient way when such a layer has been formed as a consequence of fire.Finally, Appendix C is a research paper in process of submission to the International Journal of Wildland Fire, about the formation of post-fire water repellent layers on Chilean Monterrey pine plantations. Since water repellent layers following wildfires have never been documented on Chilean soils, the need for such a publication is urgent, because Chilean land managers have been ignorant of such phenomenon.
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Cruz, Carla da [UNESP]. "Análise comparativa da evolução das boçorocas nos anos de 1962 e 1999 nos municípios de Pompéia e Oriente SP". Universidade Estadual Paulista (UNESP), 2003. http://hdl.handle.net/11449/92940.
Testo completoAbstract (sommario):
Made available in DSpace on 2014-06-11T19:26:15Z (GMT). No. of bitstreams: 0
Previous issue date: 2003-01-13Bitstream added on 2014-06-13T18:54:25Z : No. of bitstreams: 1
cruz_c_me_rcla.pdf: 5048620 bytes, checksum: c2c3ba7c2e63bbfe95d39f75f71b9604 (MD5)Realizou-se neste trabalho a análise comparativa entre boçorocas existentes no ano de 1962 com as do ano de 1999, enfocando sua evolução, estabilização e reutilização nos municípios de Pompéia e Oriente, localizados no Planalto Ocidental Paulista, Esta análise constituiu-se de fotointerpretação de fotografias aéreas da área de estudo, na escala 1:25. 000, e trabalhos de campo que incluíram o cadastramento e mensuração das boçorocas do primeiro período, e suas alterações recentes ao longo destes anos, bem como novas boçorocas na mesma área para efeitos de comparação e atualização. Os municípios estudados, ficam entre as cidades de Tupã e Marília, área de aproximadamente 20 km , constituída geologicamente pelas Formações Marília e Adamantina pertencentes ao Grupo Bauru e geomorfologicamente pelos Planaltos Residual de Marília e Centro Ocidental. A metodologia aplicada neste caso constou de levantamento geológico expedito, análise pedológica parcial e delimitação da compartimentação geomorfológica. Estes elementos foram analisados a luz das atuais condições climáticas, da atual vegetação e do recente uso e ocupação do solo e suas implicações com as boçorocas anteriores e as atuais. Esta análise implicou na proposta de estabelecer a interação entre as características naturais associadas às atividades antrópicas e ao processo erosivo implantado na área em questão. Obteve-se com a comparação dos resultados à influência conjunta dos fatores citados na ocorrência de erosões e na permanência do processo erosivo nos municípios estudados, verificando-se modificações nas boçorocas de 1962, tendo sido utilizados meios de contenção e de reutilização dessas feições erosivas. Em outros casos, as boçorocas apresentaram quadro de estabilização natural. Demonstrou-se com os dados obtidos que a mudança...
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Oliveira, Rodolfo Lopes de Souza. "Análise e caracterização da dinâmica geomórfica erosiva da área urbana de Alfenas, sul de Minas Gerais". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/8/8135/tde-13052015-112055/.
Testo completoAbstract (sommario):
Os processos relativos à urbanização promovem alterações nas dinâmicas naturais, inclusive, sobre o relevo. Assim, a Geomorfologia apresenta-se como uma área de conhecimento importante para orientar a ocupação, estudando a evolução das formas e como estas passam a ser definidas na paisagem. Por essa premissa, este trabalho objetiva analisar o grau de suscetibilidade dos materiais superficiais e da morfologia do relevo da área urbana de Alfenas MG a processos erosivos, justificando-se pela sua proposta de direcionamento para entender as respostas e as reações do relevo e do uso do solo às precipitações, ao comportamento da hidrologia (superficial e subsuperficial) e às interferências antrópicas, tendo por base informações detalhadas sobre esses elementos, pois há modificações nos fluxos de matéria e de energia operantes. Isso ajuda a explicar as ocorrências de processos erosivos da área, além de prever estados da morfologia onde estão operando esses processos ou seja, até mesmo para compreender a antropogeomorfologia da área. A área de estudo corresponde à sede do município de Alfenas, localizada entre as coordenadas de 21º15 e 21º35 de latitude S e 46º00 e 46º50 de longitude W, incluída na carta topográfica de Alfenas, na escala 1:50.000. Foram utilizados materiais como a Planta Cadastral de Alfenas e fotografias aéreas na escala de 1:6.000, além de sistemas de informações geográficas e mapeamentos de detalhe para as análises, bem como ensaios de campo e de laboratório. Com a análise de dados morfométricos e da mecânica dos materiais superficiais, foi possível identificar e caracterizar os processos erosivos observados nos compartimentos de relevo definidos. Constatou-se que a ocupação antrópica alterou as formas e tem, de fato, contribuído para a deflagração de erosão acelerada.Urbanization causes changes in natural dynamics, including relief. On this way, Geomorphology represents an important scientific area that helps to guide occupancy actions, due to morphology evolutions studies and how forms are defined in landscape. Starting by this point, this work aims to analyze the level of susceptibility of surface materials and morphology of urban area of Alfenas, Minas Gerais, Brazil, to erosion. This is justified by a proposed guidance to understand the responses and the reactions of relief to land use, climate precipitation, hidrology (superficial and subsuperficial) and antropic processes, based on detailed information about these elements, because there are changes in flows of matter and energy operant. All of this helps to explain the occurrence of erosion in the area, besides to preview morphology states where erosional processes are occurring ie, even to understand the antropomorphology of area. The study area is the city of Alfenas, Minas Gerais, Brazil, located between coordinates 21º15 and 21º 35 of latitude S and 46º00 and 46º50 of longitude W, included in topographic map of Alfenas (scale 1:50.000). Materials such the Cadastral Plant of Alfenas and aereal photographs (scale 1:6.000), as well geographic information systems, detail mapping and geotechnic essays were used for analysis. The obtained morphometric and surface materials mechanics data were fundamental to identify and to characterize erosional processes observed on the defined forms. It was found that human occupation has altered the forms and has contributed to the outbreak of accelerated erosion.
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Schmidt, Walter, e Marcus Schindewolf. "Erosion 3D Sachsen". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-38172.
Testo completoAbstract (sommario):
Für die Erstellung von Bewirtschaftungs- und Maßnahmenplänen (FFH, EU-WRRL) ist es erforderlich, den bislang noch sehr hohen Aufwand für die Datenbeschaffung und -generierung im Rahmen der Modellierung mit EROSION 3D zu senken. Erreicht werden soll eine schnellere sowie effizientere Abschätzung von Landnutzungsänderungen, Landschaftseingriffen, des Klimawandels usw. auf Oberflächenabfluss, Bodenabtrag sowie Sedimenteintrag in Gewässer mit EROSION 3D.
Im vorliegenden Projekt ist es gelungen, Parametrisierung und Modellanwendung so zu kombinieren, dass eine Bodenabtragssimulation mit dem Modell EROSION 3D flächendeckend für Sachsen mit vertretbarem Zeitaufwand durchführbar ist.
Der korrigierte und angepasste Geo-Basisdatensatz liefert die Primärinformationen zur Datenbankabfrage der Parametrisierungssoftware DPROC. Durch eine interaktive Flächenauswahl, kombiniert mit einem Flächendatenzuschnitt, können Landnutzungs- und Bearbeitungsszenarien für hydrologische Einzugsgebiete oder Oberflächenwasserkörper schnell parametrisiert werden. Die grundlegend korrigierte und erweiterte Datenbank des DPROC erlaubt die verbesserte Abschätzung erosionsrelevanter Bodenparameter, besonders für die dauerhaft konservierende Bodenbearbeitung und die Direktsaat. Die umfangreiche Dokumentation der Arbeitsschritte und die Transparenz der Datenbank ermöglichen es, jederzeit Aktualisierungen (Geo-Basisdaten) und Erweiterungen (DPROC-Datenbank) vorzunehmen.
Von den Projektergebnissen profitieren vor allem die Anwender des Programms EROSION 3D.
Beim Druck des Dokumentes ist zu beachten, dass die Karten im Format DIN A3 erstellt wurden.
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Dormoy, Thomas Gerard. "Arctic Coastal Erosion". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-27046.
Testo completoAbstract (sommario):
With the recent increase of interest in Arctic, the need rises for new tools for understanding the typical mechanisms of this very unique and so vulnerable area. The coast, which concentrates nearly all of the human activities, is in the front line and probably the most critical part of the system. Trough the past decades, mappings of the Arctic’s shorelines point out huge erosion rates and show the threat of a climate change upon the coast. Recent studies seem to link those tremendous moves to the annual thermal variations within the soil. However, the mechanisms of thermal abrasion that are suggested to be at the hearth of the process are not yet completely understood.In answer for the need of numerical models for thermal analysis of the erosion process, this thesis proposes a toolbox specially designed, based on literature review and fieldwork data. Trough the chapters, the reader shall find essential tools for estimations of the heat transfer into a soil and complete understanding of the physical mechanisms behind. Critical parameters that influence the erosion process are highlighted. To assess the operational deployment of those tools, a thermal analysis of a site has been performed. The conclusions demonstrate the capacity of numerical models to underline the critical gears of the heat transfers, and hopefully will help understanding the erosion processes of this particular place.
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Cruz, Carla da. "Análise comparativa da evolução das boçorocas nos anos de 1962 e 1999 nos municípios de Pompéia e Oriente SP /". Rio Claro : [s.n.], 2001. http://hdl.handle.net/11449/92940.
Testo completoAbstract (sommario):
Orientador: Joel Barbujiani SígoloBanca: Leandro Eugenio da Silva Cerri
Banca: Paulo César Fonseca Giannini
Resumo: Realizou-se neste trabalho a análise comparativa entre boçorocas existentes no ano de 1962 com as do ano de 1999, enfocando sua evolução, estabilização e reutilização nos municípios de Pompéia e Oriente, localizados no Planalto Ocidental Paulista, Esta análise constituiu-se de fotointerpretação de fotografias aéreas da área de estudo, na escala 1:25. 000, e trabalhos de campo que incluíram o cadastramento e mensuração das boçorocas do primeiro período, e suas alterações recentes ao longo destes anos, bem como novas boçorocas na mesma área para efeitos de comparação e atualização. Os municípios estudados, ficam entre as cidades de Tupã e Marília, área de aproximadamente 20 km , constituída geologicamente pelas Formações Marília e Adamantina pertencentes ao Grupo Bauru e geomorfologicamente pelos Planaltos Residual de Marília e Centro Ocidental. A metodologia aplicada neste caso constou de levantamento geológico expedito, análise pedológica parcial e delimitação da compartimentação geomorfológica. Estes elementos foram analisados a luz das atuais condições climáticas, da atual vegetação e do recente uso e ocupação do solo e suas implicações com as boçorocas anteriores e as atuais. Esta análise implicou na proposta de estabelecer a interação entre as características naturais associadas às atividades antrópicas e ao processo erosivo implantado na área em questão. Obteve-se com a comparação dos resultados à influência conjunta dos fatores citados na ocorrência de erosões e na permanência do processo erosivo nos municípios estudados, verificando-se modificações nas boçorocas de 1962, tendo sido utilizados meios de contenção e de reutilização dessas feições erosivas. Em outros casos, as boçorocas apresentaram quadro de estabilização natural. Demonstrou-se com os dados obtidos que a mudança...(Resumo completo, clicar acesso eletrônico abaixo)
In this work in two cities, Pompéia and Oriente, located in São Paulo State, a comparative analysis of gully erosion verified in 1962 and 1999was carried out to verify their development, stabilization and reutilization. The tools used for the analysis were photo interpretation of air photographs of the area studied, using the 1:25.000 scale, as well as works in loco including register and measurement of the gully erosion in the first period and its recent changes, together with further erosion in the same area, aiming additional comparison and updating. The two towns object of this study are located between the cities: Tupã and Marília, in an area of around 20 km2 , with Geologic Formations - Marília and Adamantina - belonging to the Bauru Group, and Geomorphologic Formation with Plateaus - Central Western and Planalto Residual in Marilia. The approach used consisted of expeditious geologic raising, partial Pedologic analysis, and delimitation of geomorphologic compartments. These were analysed in the light of the current climate conditions, woods and recent soil utilization and occupation with their implications for the previous and present gully erosion. The proposal of this analysis was to establish the interaction between the natural conditions and human activities and the erosive process implemented in the area. The comparison of results showed the influence of both factors on the erosion and running erosive process in the towns focused, with changes in the gully erosion of 1962, where means of contention and reutilization were used. In other cases the gully erosion showed natural stabilization. As a result of the intense erosive process in the 60s, the Aguapeí River Basin shows obstruction impairing the water flow. In some affluents several levels of terrace plain of sediments narrow the channels and only few centimeters of water flow...(Complete abstract click electronic access below)
Mestre
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Dun, Shuhui. "Adapting WEPP (Water Erosion Prediction Project) for forest watershed erosion modeling". Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/Summer2006/S%5FDun%5F073106.pdf.
Testo completo
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Ferdos, Farzad. "Internal Erosion Phenomena in Embankment Dams : Throughflow and internal erosion mechanisms". Doctoral thesis, KTH, Byggvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193627.
Testo completoAbstract (sommario):
In this study, two major internal erosion initiation processes, suffusion and concentrated leak mechanisms, which lead to both defect formation in a dam’s body and its foundation and high throughflow in dams subjected to internal erosion were studied. This understanding has the potential to facilitate numerical modelling and expedite dam safety assessment studies. The throughflow properties of coarse rockfill material were studied by; analysing filed pump test data, performing extensive laboratory experiments with a large-scale apparatus and numerically simulating the three-dimensional flow through coarse rock materials, replicating the material used in the laboratory experiments. Results from the tests demonstrate that the parameters of the nonlinear momentum equation of the flow depend on the Reynolds number for pore Reynolds numbers lower than 60000. Numerical studies were also carried out to conduct numerical experiments. By applying a Lagrangian particle tracking method, a model for estimating the lengths of the flow channels in the porous media was developed. The shear forces exerted on the coarse particles in the porous media were found to be significantly dependent on the inertial forces of the flow. Suffusion and concentrated leak mechanisms were also studied by means of laboratory experiments to develop a theoretical framework for continuum-based numerical modelling. An erosion apparatus was designed and constructed with the capability of applying hydraulic and mechanical loading. Results were then used to develop constitutive laws of the soil erosion as a function of the applied hydromechanical load for both suffusion and concentrated leak mechanisms. Both the initiation and mass removal rate of were found to be dependent on the soil in-situ stresses. A three-dimensional electrical-resistivity-based tomography method was also adopted for the internal erosion apparatus and was found to be successful in visualising the porosity evolution due to suffusion.QC 20161006
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Boden, Wiebke. "Prediction of erosion damages in hydraulic machines for hydro-abrasive erosion". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC034/document.
Testo completoAbstract (sommario):
L’énergie hydraulique, où l’énergie cinétique de l’eau est transformée en énergie électrique, représente une contribution importante aux énergies renouvelables. L’eau qui passe par les turbines hydrauliques contient toujours une partie solide, par exemple du sable et de l’argile. Ces sédiments peuvent atteindre des niveaux de concentration élevés, ce qui nuit considérablement à la structure de la turbine par un mécanisme d’endommagement appelé érosion hydro-abrasive. Des types de turbine impliquant des vitesses d’écoulement très élevées, comme les turbines Pelton, sont particulièrement sensibles à l’érosion hydro-abrasive. Les simulations numériques présentent un moyen efficace d’étudier le sujet de l’érosion hydro-abrasive dans les turbines Pelton car elles permettent facilement la variation des nombreux paramètres. Ainsi, une réponse immédiate aux questions opérationnelles, de conception ou d’optimisation peut être obtenue. Cependant, il a été démontré que l’application des modèles d’érosion généraux et souvent utilisés ne fournit pas de résultats corrects en raison des propriétés particulières du matériel et de l’écoulement des turbines Pelton. Par conséquent, ce travail étudie le potentiel de la modélisation de l’érosion directe basée sur des principes fondamentaux. Cela implique que le mouvement des sédiments dans le fluide est simulé, leurs paramètres au moment de l’impact enregistrés et ensuite l’endommagement macroscopique global du matériel calculé sur la base des simulations de structure en microéchelle. Une formulation très appropriée pour les simulations fluides dans les turbines Pelton est une méthode sans maillage, plutôt nouvelle, qui s’appelle Smoothed Particle Hydrodynamics (SPH). Par conséquent, la première partie de ce travail aborde la mise en oeuvre et l’évaluation d’un modèle Lagrangien de transport des sédiments dans le cadre de cette méthode où les sédiments sont transportés par une équation de mouvement. L’effet du bruit inhérent à la méthode SPH sur le mouvement des sédiments est évalué par rapport à l’effet de la dispersion turbulente des sédiments, qui a été introduite par un modèle basé sur l’équation de Langevin. En outre, les termes liés aux différentes forces dans l’équation du mouvement sont étudiés dans le cadre de la méthode SPH. Une deuxième partie de ce travail développe une approche efficace et généralement applicable pour obtenir l’endommagement globale sans adopter des modèles d’érosion. Pour obtenir cet endommagement global en macroéchelle, l’endommagement causé par un seul impact de sédiment, qui est calculé par des simulations de structure en microéchelle, est combiné avec les statistiques d’impact des simulations du fluideHydraulic energy represents one important contribution to the growing source of renewable energies where the kinetic energy of water is transformed into electric energy. The water flowing through the hydraulic turbines always contains a solid part, for example sand and clay. Those sediments can reach high concentrations, harming importantly the turbine structure by a mechanism called hydro-abrasive erosion. Turbine types implying very high flow velocities, like Pelton turbines, are in particular sensitive to hydro-abrasive erosion. Numerical simulations present an efficient way to study the topic of hydro-abrasive erosion in Pelton turbines as they allow the variation of numerous parameters. Thus an immediate response to operational, design or optimization questions can be obtained. However it has been shown that the application of general, widely used erosion models do not deliver physical correct results due to the particular material and flow properties of Pelton turbines. Consequently this work investigates the potential of erosion modeling based on first principals. That means the sediment movement in the fluid is simulated, their state at impact tracked and then the overall macroscopic material damage calculated based on microscale structural simulations. A convenient formulation for fluid simulations in Pelton turbines is the rather novel, meshless method Smoothed Particle Hydrodynamics (SPH). Therefore the first part of this work addresses the implementation and evaluation of a Lagrangian sediment transport model in the framework of this method where sediments are transported by a particle equation of motion. The effect of the SPH method inherent noise on the sediment movement is evaluated against the effect of the turbulent dispersion of the sediments, which has been introduced via an ad-hoc model based on the Langevin equation. Furthermore the different force terms in the particle equation of motion are investigated with respect to the SPH method. A second part develops an efficient and general applicable approach to obtain the overall erosion damage without adopting erosion models. Therefore the damage caused by a single sediment impact is calculated by structural simulations on the microscale in a first step. In a second step that isolated damage is combined with impact statistics from the fluid simulations and hence gives the overall damage profile on the macroscale
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Bertrand, Fabienne. "Fluvial erosion measurements of streambank using Photo-Electronic Erosion Pins (PEEP)". Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/642.
Testo completoAbstract (sommario):
Fluvial erosion incites significant bridge scour and large-scale bank erosion causing estimated $1.1 billion damage in the Midwest. Conventional, manual, field monitoring methods, typically erosion pins, cross-section resurveys or terrestrial photogrammetry, used to monitor fluvial erosion rates merely provide a net change in bank surface retreat since the previous measurement. If mass wasting has occurred, the ongoing fluvial erosion would be masked. Erosion event timing, and the precise bank response to individual flow or flow hydrograph changes, is generally uncertain. Thus, a technique that automatically quantifies bank erosion on a continuous basis is needed. This study will monitor the bank response to individual flow (i.e., fluvial erosion) using the Photo-Electronic Erosion Pin (PEEP) sensors in Clear Creek Iowa. It attends to monitor a full episode of bank change, including event timings and magnitude information for specific erosion and deposition events, which can be compared to flow discharges and hydrographs. If exploited, this method can lead to more detailed analysis of bank erosion related to temporal fluctuations in the suspected hydraulic forces.
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Smith, Jennifer Lynn. "The use of rolled erosion control products (RECPs) for minimizing soil erosion". Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available, full text:, 2007. http://wwwlib.umi.com/cr/syr/main.
Testo completo
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Pickles, Matthew Jonathan. "Hydrodynamic erosion of coatings". Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243503.
Testo completo
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Duncan, Helen. "Erosion corrosion by minerals". Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278290.
Testo completo
20
Feng, Zheng, e Zheng Feng. "The erosion of materials". Doctoral thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/23076.
Testo completoAbstract (sommario):
Solid particle erosion tests of glass, stainless steel, WC-Co and sintered alumina, have been performed with seven erodents using a range of particle diameters D (63 μm - 1000 μm), velocities V (33 m.s⁻¹ - 131 m.s⁻¹ ) and impact angles α (30° - 90°). The seven erodents are steel shot, glass beads, silica, alumina, tungsten carbide, silicon carbide and diamond· particles. In addition, the target materials have been subjected to cavitation erosion using a conventional ultrasonic horn in distilled water. Systematic studies of the influence of the impact variables on the erosion rate have been made. Scanning electron microscopy of the eroded surfaces and the erodents after impact has been performed. Empirical correlations between erosion rate and the parameters of erosion and the erodents were obtained and are discussed in terms of the modes and mechanisms of erosion. A semi-quantitative theoretical model has been developed to explain the empirical correlations for brittle and ductile materials. The mode of erosion of glass impacted by irregularly shaped particles is associated with the formation and interaction of lateral cracks over all impact velocities and angles used in this study. The erosion of glass by spherical particles is determined by particle size, impingement velocity and angle. An erosion map, in which the erosion of glass is mapped against velocity and particle size, has been constructed to categorise the types of damage observed in glass for impingement angles between 90° and 30°. The erosion. behaviour of 304 stainless steel is associated with cutting or ploughing and plastic accumulation processes. The erosion of WC-Co is associated with a combination of ductile and brittle modes of erosion. The erosion of alumina is brittle and associated with intergranular spallation and grain-crushing. An analysis of the results reveals that for the brittle materials, glass and alumina, the erosion rate is determined by kinetic energy, particle size and the relative hardness and toughness of the erodents. However, for ductile materials, the shape and kinetic energy of erodents are the most important factors determining the erosion rate. There is no significant effect of hardness and toughness of erodents on erosion. Surprisingly, the erosion resistance of the softer 304 stainless steel is better than that of alumina and WC-Co when hard erodents are used at impact angle greater than 40°. On the other hand the erosion resistance of the harder WC-Co and alumina is better than that of 304 stainless steel for softer erodents like silica erodents. Glass always exhibits poor erosion resistance. In cavitation erosion, stainless steel exhibits better cavitation erosion resistance than glass, alumina and WC-Co. The cavitation erosion resistance of WC-Co is dependent upon the cobalt content. An attempt to rationalise the results in terms of mechanisms has been made. Both solid particle and cavitation erosion rate for the as received glass is higher than that for the tempered glass due to introduction of residual compressive stresses into the surface by the tempering process. Particularly, it reveals that compressive stresses are more efficient in preventing the formation and propagation of Hertzian cracks. These findings will assist in the choice and design of materials that undergo both particle and cavitation erosion under specified conditions.
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Mahoney, Erin Kathleen. "Erosion Of Primary Teeth". Thesis, Faculty of Dentistry, 2009. http://hdl.handle.net/2123/4612.
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Silveira, Patrícia Borges. "Influencia da escala nos resultados de estimativa de perda de solo por meio da EUPS /". Rio Claro, 2017. http://hdl.handle.net/11449/152620.
Testo completoAbstract (sommario):
Orientador: Cenira Maria LupinacciBanca: Leandro de Souza Pinheiro
Banca: Salvador Carpi Junior
Banca: Sérgio dos Anjos Ferreira Pinto
Banca: Fabiano Tomazini da Conceição
Resumo: Dentre os recursos naturais que o homem necessita para sobreviver, o solo se insere na lista dos mais importantes, sendo um dos suportes da produção agrícola, a fim de abastecer as populações. Contudo, pesquisadores do mundo todo têm alertado que devido à pressão de uso e ocupação da terra, os solos tendem a se modificarem pela força da água e dos ventos o que ocasionará a formação de desertos. Assim, visando contribuir com estudos que buscam a preservação e conservação dos solos para fins agrícolas, a presente pesquisa tem por objetivo colaborar com o aprimoramento de modelo preditivo de erosão (EUPS), visando uma melhor aproximação entre os dados de estimativa de perda de solo obtidos com o modelo e os dados registrados em campo. Para atingir os objetivos propostos e avaliar as hipóteses formuladas, a Equação Universal de Perdas de Solo, EUPS, foi aplicada na bacia hidrográfica do ribeirão Alam Grei, na escala de 1:10.000, utilizando três diferentes técnicas de obtenção dos valores referentes ao fator topográfico da EUPS. Tais resultados foram comparados com os dados obtidos em duas vertentes selecionadas dessa bacia na escala de detalhe de 1:1.000, a fim de verificar como a escala interfere nos resultados obtidos com o referido modelo. Os resultados mostraram que a escala de maior detalhe favorece a obtenção de dados de melhor qualidade, a fim de apresentar valores finais de EPS mais reais, já que permite a obtenção de dados menos generalizados. Além disso, os valores de e... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Among the natural resources that man needs to survive, the soil is included in the list of the most important, since without it the agricultural production, in order to supply the populations, becomes unfeasible. However, researchers around the world have warned that due to improper exploitation, the world's soils tend to change by force of water and wind, which will lead to the formation of uninhabitable deserts. Thus, in order to contribute to studies that seek the preservation and conservation of soils for agricultural purposes, this research aims to collaborate with the improvement of the predictive model of erosion (EUPS), aiming at a better approximation between the data of estimation of soil losses obtained with the model and the data registered in the field. In order to reach the proposed objectives and to evaluate the hypotheses formulated, the Universal Soil Loss Equation (EUPS) was applied in the Alam Grei river basin, in the scale of 1: 10,000, using three different techniques to obtain the values referring to the topographic factor of the EUPS. These results were compared with the data obtained in two selected slopes of this basin in the detail scale of 1: 1,000, in order to verify how the scale interferes in the results obtained with said model. The results showed that the scale of detail favors the obtaining of data of better quality, in order to present final values of more real EPS, since it allows obtaining data less generalized. In addition, the soil loss e... (Complete abstract click electronic access below)
Doutor
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Lüthi, Marcel. "A modified hole erosion test (HET-P) to study erosion characteristics of soil". Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/36999.
Testo completoAbstract (sommario):
Today’s increasing demand for energy and natural resources requires safe and reliable infrastructure. This includes hydraulic earth structures like dikes, levees, or dams. Such structures are susceptible to piping, a fundamental type of internal soil erosion. Piping is one of the principal causes of failures and accidents affecting embankment dams. The Hole Erosion Test (HET) is based on soil piping, and is used to determine the erodibility and critical shear stress of a soil. A soil specimen with a preformed axial hole is subjected to a constant-head pressure flow, and the rate of enlargement of the soil pipe is determined indirectly from flow rate and hydraulic gradient. This study presents a Modified Hole Erosion Test (HET-P) that introduces a conventional Pitot-static tube to measure total energy head and flow velocity of the exiting jet, which is correlated to a mean velocity within the axial hole. A series of Modified Hole Erosion Tests (HET-P) was performed on non-erodible PVC specimens with axial holes of constant, but different diameter, followed by HET-P tests on two types of soil, namely glacial till material of a dam core and natural clay deposits from Ontario river banks. Results confirmed that sidewall hydraulic head measurements to determine hydraulic gradients in the standard HET overestimate the resulting axial wall shear stress by as much as an order of magnitude. Furthermore, velocity measurements increase the confidence in test results as they allow for a more direct estimate of the axial hole diameter at any time during a test. A Pitot-static tube used in the HET-P for velocity and pressure measurement can easily be incorporated, and yields more transparent and reliable results by eliminating or amending some of the limiting assumptions of the standard test. It is an easy, fast, and economical approach that can be applied to soils in both constructed earth structures including dams and embankments, and to natural river banks to determine their susceptibility to internal and surface erosion.
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Choi, Daniel Mintae. "Rainfall intensity and soil erosion by water : limitations of current erosion models and implications for erosion model-based studies under future climates". Thesis, University of Oxford, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604890.
Testo completoAbstract (sommario):
Existing simulation studies of the effects of future climate change upon erosion indicate that, under land usages that leave the soil unprotected, even minor increases in rainfall amounts are likely to result in disproportionately large increases in erosion, but commonly make the simplifying assumption that distributions of future rainfall intensities remain unchanged from the present. This research aims to determine implications of rainfall -intensity changes on soil erosion using computerised models. Thus, this thesis is a step towards the ultimate goal of predicting future rates of soil erosion caused by future rainfall intensity changes. Three soil erosion models, WEPP, EUROSEM, and RillGrow are employed to investigate impacts of various rainfall intensities on runoff and soil loss rates. Two extreme daily rainfall events in summer and autumn are subjectively selected from the tipping-bucket rainfall data, and runoff and soil losses are simulated using three erosion models. Estimated runoff and soil loss rates with high resolution rainfall data are greater than those with low temporal resolution rainfall data. Within-Storm Intensity Patterns (WSIPs) affect soil erosion amount, although runoff was not much affected. An additional daily rainfall event with Within-Storm Gaps (WSGs) is also selected to investigate effects of WSG removals on soil erosion. For a given amount of rainfall, events with constant low intensity (constant WSIP) produced dramatically less erosion: thus it appears that assuming a constant (or averaged) intensity throughout a storm does not provide a good representation of a real rainfall with its continuously varying intensity. Analyses of outputs from WEPP simulations revealed a problem that WEPP modifies original rainfall intensity and, thus, simulates erroneous runoff and erosion rates. Future soil erosion rates are estimated using WEPP and CLIGEN data. 30 year-long weather is generated by CLIGEN. Likely future rainfall frequency and intensity are anticipated by changing the mean maximum 30 minutes peak intensity also known as MX.SP. No fu ture rainfall amount change is assumed. WEPP simulation results suggest that where mean maximum 30-min peak intensity of the wet months increases soil erosion increases at a greater rate than runoff. This research assists in improving the performance of erosion models with respect to changes of rainfall intensity by highlighting where current problem exists. In conclusion, greater knowledge found here will, once future changes in rainfall intensity become better known and appropriate rainfall data become available, improve our ability to estimate future rates of erosion.
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Arantes, Leticia Tondato. "Limiares topográficos de processos erosivos na bacia do Rio Bonito (SP) obtidos a partir de modelo digital de elevação de dados de radar (PALSAR/ALOS) /". Ilha Solteira, 2019. http://hdl.handle.net/11449/183328.
Testo completoAbstract (sommario):
Orientador: José Augusto LolloResumo: A erosão é um fenômeno complexo, uma vez que envolve a ação direta ou indireta de diversos fatores, tais como tipos de solos, clima, vegetação, declividade e ações antrópicas. O estudo acerca da dinâmica, agentes desencadeadores e fatores condicionantes é uma importante ferramenta para uma tomada de decisão. A proposição de índices que indicam o limiar crítico para determinar a ocorrência de processos erosivos, é uma das vertentes dos estudos acerca de processos erosivos, cuja pressupõe-se uma relação entre a declividade (S) e área de contribuição (A), que condiciona os processos de erosão. Considerando os avanços na geração dos produtos de Sensoriamento Remoto, este trabalho objetivou realizar um estudo sobre o desencadeamento das erosões lineares, no qual propõe a avaliação da empregabilidade do Modelo Digital de Elevação (MDE) gerado por meio de imagem de radar interferométrico (ALOS/Palsar) para obtenção dos parâmetros topográficos da Bacia Hidrográfica do Rio Bonito, inserida no município de Descalvado e Porto Ferreira no estado de São Paulo. Com isso o MDE, o mapa de declividades e direção de fluxo foram elaborados em ambiente SIG, com pixels de saída de 2m, possibilitando obter os valores de A versus S, utilizando o algoritmo D-Infinity para o processamento dos dados hidrológicos. Os valores obtidos forma representados em um gráfico, permitindo identificar a declividade mínima para a ocorrência de um processo erosivo, bem como estabelecer de forma empírica o limiar top... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Erosion is a complex phenomenon as it involves the direct or indirect action of various factors such as soil types, climate, vegetation, slope and anthropic actions. The study about dynamics, triggering agents and conditioning factors is an important tool for decision making. The proposition of indices that indicate the critical threshold to determine the occurrence of erosive processes is one of the strands of studies on erosive processes, whose assumption is a relationship between slope (S) and contribution area (A), which conditions the erosion processes. Considering the advances in the generation of Remote Sensing products, this work aimed to conduct a study on the triggering of linear erosions, which proposes the evaluation of the employability of the Digital Elevation Model (MDE) generated by interferometric radar imaging (ALOS / Palsar) to obtain the topographic parameters of the Bonito River Watershed, inserted in the municipality of Descalvado and Porto Ferreira in the state of São Paulo. With this the MDE, the slope map and flow direction were elaborated in GIS environment, with 2m output pixels, allowing to obtain the values of A versus S, using the D-Infinity algorithm for the hydrological data processing. The values obtained were represented in a graph, allowing to identify the minimum slope for the occurrence of an erosive process, as well as to establish empirically the topographic threshold. The index obtained in this work from the analysis was S = 0.0333A-0.0... (Complete abstract click electronic access below)
Mestre
26
Van, der Poel Petrus W. "Plunge pool erosion in cohesive channels below a free overfall /". Connect to resource, 1985. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1202403267.
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27
Thapa, Bhola. "Sand Erosion in Hydraulic Machinery". Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-302.
Testo completoAbstract (sommario):
The topic of this thesis is damage of hydraulic machinery due to sand erosion. This is a very broad topic in which all the aspects of design of hydraulic machinery namely material selection; mechanics of material and hydraulics are involved. The issue of sand erosion is equally important for operation and maintenance of hydropower plants.
The erosion damage of turbines of hydropower plants in Himalayan Rivers, in particular in Nepal, due to high sediment contents in river is a motivating factor for this research. The findings of this study are believed to help to reduce erosion of turbine components, increase their life time and improve maintenance procedure.
The objectives of this study are to:
1. Study the erosion process on different materials and compare lifetime of turbine material with hard surface coating.
2. Study the flow in the turbine and identify the region of highest velocity and acceleration where most serious sand erosion occurs.
3. Study erosion rate of turbine as a function of operating parameters (head and speed), particle characteristics and turbine material.
4. Assess loss of efficiency and to analyze repair method and repair interval that gives optimal economy of the hydropower plants.
The goals laid out in the objectives are achieved by understanding the theory of erosion of material through literature, investigating the nature of turbine damage from field observation and finally by experiments to study effect of variables of erosion rate and investigation of particle separation process in rotational flow.
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Schindewolf, Marcus. "Phosphoreinträge durch Erosion in Sachsen". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-85270.
Testo completoAbstract (sommario):
Im Projekt wurde eine Methodik entwickelt, um mit dem Modell EROSION 3D sachsenweit für erosionsauslösende Starkniederschlagsszenarien den partikelgebundene Phosphoreintrag in Oberflächenwasserkörper abzuschätzen.
Mit dieser Abschätzung und der Identifikation wassererosionsgefährdeter Ackerflächen bzw. Feststoffeintragspfade in Gewässer lassen sich zur erfolgreichen Umsetzung der EU-Wasserrahmenrichtlinie zielgerichtete Maßnahmen zum Erosionsschutz ableiten.
Die Modellierungen mit EROSION 3D zeigen, dass eine konsequente Umstellung auf konservierende Bodenbearbeitung die P-Austräge in Sachsen signifikant um 80-90 % senken würde. Die Projektergebnisse liefern wichtige Grundlagen zur P-Anreicherung im Feinbodenanteil von Ackerböden und geben einen Einblick in das Prozessverständnis der partikelgebundenen P-Austragsdynamik.
29
Zhu, Jingxu (Jesse). "Tube erosion in fluidized beds". Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/29225.
Testo completoAbstract (sommario):
Heat transfer tubes suffer erosion when immersed in fluidized beds. This has caused problems, especially in fluidized bed combustors. The mechanism of erosion for horizontal tubes in fluidized beds is not well understood. The purpose of this study was to investigate the erosion mechanism in fluidized beds and to investigate the influence of operating parameters and the mechanical properties of the particles and tube materials.
Horizontal tube erosion tests were carried out in a room temperature three-dimensional fluidized bed with a cross-section of 216 mm by 203 mm and height of 1.52 m. Sample rings of ten different materials were mounted on a solid bar and were weighed before and after each test to determine the erosion rate. The parameters tested were particle size (0.30 to 1.51 mm), particle sphericity (0.84 to 1.0), particle density, particle hardness, superficial air velocity (0.88 to 2.52 m/s), tube diameter (15 mm to 32 mm), tube configuration and material mechanical properties. Two additional types of experiments were also conducted to help understand the mechanism of erosion. In one particles were dropped freely in an empty column to impact on test specimens at different velocities determined by the dropping distance, in order to investigate erosion due to solid particle impact under known conditions. In the other the particle movement was filmed in the vicinity of a horizontal tube in a two-dimensional fluidized bed in order to investigate the particle flow pattern around a tube. A small number of tests were also conducted at high temperatures.
The erosion of a horizontal tube in fluidized beds was found to be caused mainly by the impact of solid particles on the lower surface. Erosion was found to be strongly dependent on the particle impact velocity, which is closely related to the void (bubble or slug) rise velocity. The void rise velocity, in turn, is determined by the mean void size which depends on the superficial air velocity, column size and other fluidizing conditions. Particle diameter also has a strong influence on erosion. The target material Young's modulus appears to be the major mechanical property which is closely related to the erosion rate caused by solid impact erosion. Of the materials tested, all non-ferrous metals suffer much more erosion than ferrous metals. Localized high particle velocities due to jets and at bends or near feed points can be extremely harmful.
The mechanism of erosion caused by low velocity (< 6m/s) solid particle impacts appears to be different than that caused by high velocity (> 30m/s) impacts reported in the literature, although there are some similarities in trends. The erosion at low impact velocities appears to be mainly due to a surface fatigue process, which, instead of plastically deforming a small amount of target material for every impact, deforms the target materials in the elastic range and causes them to crack on or underneath the surface leading to removal of materials.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
30
Duncan, S. "Ion erosion in surface analysis". Thesis, Loughborough University, 1985. https://dspace.lboro.ac.uk/2134/28023.
Testo completoAbstract (sommario):
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.
31
Zhang, Yu 1965. "Erosion behaviour of engineering ceramics". Monash University, School of Physics and Materials Engineering, 2002. http://arrow.monash.edu.au/hdl/1959.1/8404.
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32
Godwin, Ian Chandler Paterson. "Physiographic Components of Trail Erosion". Thesis, Montana State University, 2000. http://etd.lib.montana.edu/etd/2000/godwin/GodwinI_00.pdf.
Testo completoAbstract (sommario):
No previous study has sought to discriminate between soil erosion and soil compaction when explaining the "missing" cross-sectional areas of incised trails, assuming instead that erosion was the dominant process. Separating the two processes of erosion and compaction is critical to understanding the relationship between physiographic variables and the structure of trails. The purposes of this project are to estimate the relative effects of compaction and erosion on trail cross sectional area along the New World Gulch Trail, Montana, and to better understand the relationship between erosion, compaction, local topography, vegetation, soil bulk density, and soil texture. The following hypotheses were addressed: 1) adjusting the incised cross sectional area of a trail, by removing the effects of soil compaction, will increase the amount of variance in erosion explained by collected physiographic variables; and 2) inclusion of soil bulk density and soil texture as physiographic variables will increase the amount of variance in cross-sectional area explained along the trail. The goals of this study required the collection of field data, analysis of soil samples, and statistical analysis of data. Soil samples and other field measurements were collected over several months during the summer and fall of 1994. Some of the topographic information used in the statistical analysis originated in Urie's (1994) study of recreational trails. The determination of trail slope as one of the primary components of trail incision is consistent with previous studies. Soil water content is the second most significant independent variable when the percentage of particle sizes are not considered. Percent vegetative cover is also significant in the stepwise regression, although it is not significantly correlated to cross-sectional area. The most significant variable added to those already studied was soil bulk density. When individual variables were regressed against the measured cross-sectional area, off-trail soil bulk density accounted for the second greatest amount of variance (r² = 0.12) after trail slope (r² = 0.35). The ratio of on-trail soil bulk density to off-trail soil bulk density, which could be considered a measure of compaction, accounted for even more variance (r² = 0.18) than soil bulk density.
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Eltvik, Mette. "Sediment erosion in Francis turbines". Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22755.
Testo completoAbstract (sommario):
Sediment erosion is a major challenge for run-of-river power plants, especially during flood periods. Due to the high content of hard minerals such as quartz and feldspar carried in the river, substantial damage is observed on the turbine components. Material is gradually removed, thus the efficiency of the turbine decreases and the operating time of the turbine reduces. Hydro power plants situated in areas with high sediment concentration suffer under hard conditions, where turbine components could be worn out after only a short period of three months. This short life expectation causes trouble for energy production since the replacement of new turbine parts is a time consuming and costly procedure. It is desirable to design a Francis runner which will withstand sediment erosion better than the traditional designs. The literature states that an expression for erosion is velocity to the power of three. By reducing the relative velocities in the runner by 10%, the erosion will decrease almost 30%. The objective is to improve the design of a Francis turbine which operates in rivers with high sediment concentration, by looking at the design parameters in order to reduce erosion wear. A Francis turbine design tool was developed to accomplish the parameter study. In the search for an optimized Francis runner, several design proposals were compared against a reference design by evaluating the turbine’s performance. The hydraulic flow conditions and the prediction of erosion on the turbine components are simulated by analyzing the models with a Computational Fluid Dynamic (CFD) tool. A Fluid Structure Interaction (FSI) analysis ensures that the structural integrity of the design is within a desired value. Results from this research show that it is feasible to design a runner with an extended lifetime, without affecting the main dimensions and hydraulic efficiency.
34
Szente, Roberto Nunes. "Erosion of plasma torch electrodes". Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74256.
Testo completoAbstract (sommario):
The erosion of copper electrodes in a concentric cylinder geometry with magnetically driven arcs was studied at steady state for currents up to 250 A in a variety of gases and gas mixtures, magnetic field strengths and gas flow rates. The effects of arc velocity, gas composition, current density and heat transfer to the cathode on erosion rates were examined.The arc velocity varied with the magnetic field strength and arc current accordingly to a newly developed equation, V $ alpha$ B$ sp{0.60}$ I$ sp{0.56}$, when the cathode surface was slightly contaminated with C, Cl, O or N. The composition of the surfaces was found using Auger and ESCA spectroscopy. A surface drag force, a new force opposing to the arc motion was proposed. In the case of clean and heavily contaminated surfaces (contaminant layers thicker than 10 microns), the surface drag becomes the major force opposing the arc movement. Work function measurements showed that surface drag increased as electron emission became more difficult.
A novel technique was developed to determine the current distribution of the arc foot on the electrodes. A correlation between the arc foot current density and erosion rate was proposed. The effects of the surface composition, magnetic field and arc velocity on the arc current distribution were also examined.
A conceptual model was developed for electrode erosion; the model was supported by experimental results and by the results of simulations using macroscopic and microscopic heat transfer models.
35
Ewunkem, Asoumu Emmanuel. "Cavitation erosion of engineering materials". Thesis, City University London, 1993. http://openaccess.city.ac.uk/8358/.
Testo completoAbstract (sommario):
The work presented in this thesis is concerned with evaluating the erosion resistance or behaviour of various engineering materials to cavitation erosion in a through flow device. A wide range of engineering materials have been utilized, from metal alloys, plastics, ceramics to composiles. These were procured from various industrial and research establishments. The metal alloys which were supplied in various condition of heat treatments, ranged from aluminium alloy to nitrided and tool steels. The plastic employed were epoxy resins. These were supplied in two different formulations the "Novalac" and the Bisphenol" systems. They were produced in as cast and machined conditions. Thus the influence of both the formulation and the production processes on their cavitation erosion behaviour have been analysed. Silicon carbide arid silicon nitride were the ceramic materials employed in this project. Both were produced under three surface finish conditions. These were fired or sintered, ground and lapped respectively. The performances of all three surface finishes have been elucidated and the cavitation erosion resistance of both silicon carbide and silicon nitride have been ascertained. Glass reinforced plastic (GRP) and Fybroc were the composites utilized. They both employed glass fibre as the reinforcing element. Their cavitation erosion behaviour and resistance have been evaluated. Detailed observation of damage progression in the above three classes of materials have been made. A comprehensive cavitation erosion test data base has been obtained. An appraisal on a comparative basis of the different erosion rates of the various material tested is presented.
36
Scullion, I. M. "Erosion by solid particle impact". Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234058.
Testo completoAbstract (sommario):
Basic single particle impact studies were carried out on copper, steel and dural. By calculating the coefficient of restitution without employing the usual small indentation approximations, closer agreement was found with experimental data. The experimentally determined dynamic hardness was found to be between 1.3 and 1.4 times the quasi-static indentation hardness. A notable feature of these experiments was the formation of surface rings in the bottom of the impact crater. These impacts were analysed in a manner analogous to that used for the impact of a liquid drop on a rigid substrate where damage is caused by the detachment of the shock wave from the contact periphery. An extension of the single particle impact studies was an investigation into the chipping car paint. The failure mechanism was found to be primarily shear debonding at the coating/substrate interface which facilitated the formation of chips and subsequent corrosion of the metal substrate. Suggestions were made to improve the performance of the paint system. In the area of multiple particle impact, considerable improvements were made to the existing erosion apparatus and associated instrumentation, particularly in the area of particle velocity measurement. This was then used to investigate the behaviour of a range of materials including pure metals, nimonic alloys and polymer specimens. The nimonic alloys were found to have an angular response more typical of a brittle material than of a ductile metal. Most of the materials studied exhibited incubation times which were shown to correspond to between ten and several hundred impacts on the same target area. Study of titanium metal (which emits sparks during erosion) at normal incidence showed that some mass loss is actually occurring throughout the incubation period, although the specimen may be exhibiting a net mass gain. This mass loss is thought to be due to a single impact mechanism such as cutting or ploughing, which is then swamped by a co-operative mechanism to produce a linear erosion rate. The incubation period cannot therefore be due solely to the superposition of a linear mass loss and a saturating rate of embeddment.
37
Harris, P. K. "Erosion in centrifugal compressor impellers". Thesis, Cranfield University, 1996. http://dspace.lib.cranfield.ac.uk/handle/1826/10622.
Testo completoAbstract (sommario):
An experimental and theoretical study of erosion in centrifugal compressor impellers is
presented. An experimental rig using laser anemometry techniques was employed to create
a database of particle restitution ratios for a range of materials. This data was unique in
that the particle rebound was measured in a quiescent condition where the aerodynamic
effects had been minimised, and also parametric factors not previously available were
included. These values were incorporated into the existing Particle Trajectory Code
developed by Cranfield University and Rolls Royce PLC. The code is used to calculate
the trajectories of discrete particles in three dimensional gas turbine geometries, and the
ensuing erosion. It was modified to include the effects of the periodic boundary
conditions, particle fragmentation, splitter blades, and variations in inlet dust concentration
profile. Flowfield calculations were performed on a Rolls Royce GEM-2 and splittered
GEM-60 impeller, which both represent the high pressure stage of the axial + centrifugal
compression system of GEM engines. A procedure developed by Tourlidakis, for the
analysis of steady viscous flow in high speed centrifugal compressors with tip leakage,
was used to generate the flowfields. The GEM-2 impeller flowfield was analysed at 1009c
speed, and validated with calculations and measurements which had been taken for
previous projects. Simulated erosion data under the same conditions was checked using
practical results obtained in a Rolls Royce PLC Helicopter Engine Environmental
Protection Programme, and good agreement was achieved. In order to provide a qualitative,
experimental assessment of erosion, a GEM-60 impeller was coated with four layers of
paint of different colours. Two sizes of quartz particle, each at three different vane
heights, were then seeded into the impeller while it was run cold at (the maximum) 70%
speed. The erosion patterns generated compared well with the results generated by the
Particle Trajectory Code.
38
Hankey, S. E. "Cavitation erosion of WC-Co". Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/21135.
Testo completoAbstract (sommario):
Bibliography: pages 68-70.An investigation involving the vibratory cavitation erosion of WC-Co alloys was undertaken in order to determine the mechanisms of material removal. Nineteen grades of WC-Co alloys were studied. These alloys had been previously characterised according to microstructural and mechanical properties. Further characterisation by way of Young's modulus and density of the materials was undertaken. An investigation of the i nfluence of various parameters on cavitation erosion established a binder content dependence on erosion. For two grain sizes, erosion was found to increase to a maximum at 12 vo1-% binder content (1.8 μm grain size) and 23 vol-% binder (2.8 μm grain size). The main mode of material removal was found to be cobalt removal followed by WC grain pull-out. In high binder content alloys, cobalt removal was predominant with little loss of WC grains. X-ray diffraction showed that the allotropic phase transformation of the binder under cavitational attack was beneficial to the erosion resistance of these alloys. The erosion of low binder content alloys was controlled by the contiguity of the WC skeleton. Maximum erosion occurred at binder contents which corresponded to the combination of a fragile WC skeleton and a small volume of available cobalt for strain induced transformation.
39
Wellman, R. G. "Solid particle erosion of ceramics". Master's thesis, University of Cape Town, 1993. http://hdl.handle.net/11427/18219.
Testo completoAbstract (sommario):
The zeolite ZSM-5 is well-known for its unique intersecting channel system. This channel system has a great bearing on the shape-selective properties and the long life-times of ZSM-5. In this study, ZSM-5 was modified in various ways to eliminate the external acidity of the catalyst to further improve these properties, and the success and effects of these modifications were investigated primarily using temperature programmed desorption techniques. The internal surface of ZSM-5, a medium pore zeolite, plays a major role in the shape selective properties of this catalyst, due to the diffusional restrictions imposed by the channel system on bulky molecules. Even though the number of acid sites on the external surface is small compared to the total number of acid sites, these easily accessible and non-shape selective acid sites may provide a high turnover rate for non-shape selective reactions. Furthermore, the main cause of deactivation of ZSM-5 is thought to be the formation of polyaromatic molecules on the external surface, which block access to the channels of the catalyst.
40
Conforto, Sesto Juan R. "Erosion in Southern Monterey Bay". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Mar%5FConfortoSesto.pdf.
Testo completoAbstract (sommario):
Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, March 2004.Thesis advisor(s): Edward B. Thornton, James MacMahan. Includes bibliographical references (p. 37). Also available online.
41
Pilippu, Hewage Eranga Dulanjalee. "Erosion and entrainment during landslides". Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/28901.
Testo completoAbstract (sommario):
The main focus of this thesis is to experimentally investigate the effect of grain size on the mechanism of erosion during landslides using small-scale laboratory experiments. Specifically, we have focused on the effect of the grain size of the flowing and erodible bed materials on the erosion rate. We experimentally investigated a flow of particles over an erodible base in a laboratory-scale inclined flume with different particle size combinations for the flow and the erodible substrate. The dynamics of the flow-erodible bed interface was captured with X-ray radiography. The evolving erosion depths were estimated from the well-established critical velocity-based method and a novel particle size-based method.
The erosion rates estimated from the two techniques gave contradictory conclusions. The normalized erosion rate increases with the flow to bed grain size ratio in the critical-velocity-based erosion rate estimation, whereas the erosion rates estimated from the particle-size-based approach encounter the opposite trend. To further investigate this behaviour, we have developed a one-dimensional continuum model which incorporates the kinematics of the flowing system. The observed erosion behaviour interpreted from the bidisperse calibration method is reproduced with this model reasonably well. The effect of size-based segregation in these flows is found to be minimal, however overall, we observed reverse segregation in the flow system.
In this research, we successfully captured the internal micromechanics of the flow field with X-ray radiography. This imaging methodology allows us to probe deeply within the flowing material, avoiding limitations in data capturing only near sidewalls that are prevalent with other imaging methods. In contrast to the critical velocity-based technique, the newly developed bidisperse calibration technique precisely determined the flow-erodible bed interface.
42
Chun, Wang. "Erosion-corrosion mitigation using chemicals". Thesis, University of Leeds, 2007. http://etheses.whiterose.ac.uk/747/.
Testo completoAbstract (sommario):
The presence of entrained sand in oil and gas production is becoming increasingly prevalent as wells age and this is leading to erosion-corrosion in C02-saturated conditions becoming a major mechanism of material attack. Its understanding, prediction and control are key challenges to sound facilities design. The use of carbon steel in conjunction with corrosion inhibitors in preventing erosioncorrosion has been observed as an economically viable solution for oil and gas piping systems. In order to produce highly effective corrosion inhibitors, it is important to understand how inhibitors act on each of the components of erosion-corrosion. Although research into corrosion inhibition has been extensively conducted, there is less documentation of inhibitors in retarding erosion-corrosion. This thesis has attempted to construct a quantitative structure relationship between erosion, corrosion and their synergistic effects to investigate erosion-corrosion and inhibition mechanisms with four fully formulated CO2 inhibitors (CGO, CRO, CRW8 and CRW9) along with some mechanistic studies involving single components from inhibitor formulations. Two experimental set-ups were used: a rotating cylinder electrode (RCE) and a submerged impinging jet (SIJ). In both experimental methodologies, gravimetric measurement, cathodic polarisation, Linear Polarisation and AC impedance techniques were used to ascertain the extent of corrosion as a function of conditions and inhibitor dosing/type. Both RCE and SIJ test samples were studied using surface analysis techniques such as scanning electron microscope (SEM), Light microscope, Energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS). In this thesis, through integration of electrochemical analysis and gravimetric measurements the damage has been identified as being associated with mechanical erosion, electrochemical corrosion or interactive electrochemical/mechanical processes. The role that inhibitors can play in reducing damage in addition to that caused by corrosion, namely by erosion and their synergistic action has been shown. Under both configurations. erosion-corrosion interactions play a major role in damage with corrosion being a controlling parameter. The thesis has made substantial advances in the understanding of the extent to which corrosion inhibitors could be used to control erosion-corrosion damage and in understanding the mechanisms of how this can be achieved.
43
Meng, Hang. "Erosion-corrosion of marine alloys". Thesis, University of Leeds, 2009. http://etheses.whiterose.ac.uk/12739/.
Testo completoAbstract (sommario):
Marine alloys such as stainless steels, copper-base alloys and cast iron have a long history of applications over a wide range of industries. They always are exposed to aggressive erosion-corrosion environments to support or transmit forces during the service, where more than millions of pounds are involved to repair the material degradation every year. In order to minimize this cost, lots of money and research have been put into practice, from which more and more erosion-corrosion behaviour and mechanisms of marine alloys were understood, however, downtime of marine systems still happens, moreover it is still a fact that it is quite difficult to choose the optimum material for the specific working environment. In this project, erosion-corrosion performance of eight marine alloys which include three different grade stainless steels, four copper-base alloys and one Niresist cast iron has been assessed under liquid-solid jet impingement over eight sets of test conditions in 3.5% sodium chloride solution. Firstly, the weight loss of different marine alloys ranks the priority of their corrosion, erosion and erosion-corrosion resistance over the range of the test conditions, furthermore the total weight loss test, in conjunction with in-situ electrochemistry measurements, enable the relative contribution of the different mechanisms interacting in the degradation to be quantified, meanwhile the aspects of erosion-corrosion mechanisms of different marine alloys have been detailed. Even erosion-corrosion is a complex process, but microhardness has been found to be the controlling factor in severe erosion-dominated conditions. More importantly, primary concerns have been brought on the factorial contributions of individual environmental parameters and their interactions to the overall material degradations. A full two-level factorial experimental design method combined with following analysis of variance was applied to qualify these factorial contributions, which shows effects of the individual environmental parameters and their interactions on the weight loss during the erosion-corrosion processes, and the prominent factors are velocity, sand loading and their interaction. Fluid temperature has the smallest effect compared with other environmental parameters.
44
Deneke, Fred. "Soil Erosion Control after Wildfire". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2002. http://hdl.handle.net/10150/146945.
Testo completo
45
DeGomez, Tom. "Soil Erosion Control after Wildfire". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2011. http://hdl.handle.net/10150/239603.
Testo completo
46
Pineda, Rondon Saira Freda. "Numerical prediction of cavitation erosion". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC031/document.
Testo completoAbstract (sommario):
La cavitation peut avoir lieu dans les turbines hydrauliques. Ce phénomène se produit lorsque les bulles de vapeur s’effondrent à proximité de la surface de la machine. Ceci entraîne des conséquences négatives, telles que l’érosion, affectant ainsi les performances de la machine. L’effondrement d’une bulle de gaz non-condensable dans l’eau est simulé en utilisant la méthode sans maillage SPH-ALE, qui intègre un modèle pour simuler les écoulements compressibles et multiphases. Le modèle résout les équations de conservation de masse, de quantité de mouvement et d’énergie du système d’Euler, en utilisant l’équation d’état de Stiffened Gas pour l’eau et l’équation d’état de gaz parfait pour le gaz non-condensable à l´ıntérieur de la bulle. Les deux phases sont modélisées comme compressibles et le changement de phase n’est pas considéré. La caractéristique sans maillage de la méthode SPH-ALE permet le calcul des écoulements diphasiques où l’interface est nettement définie. Pour les applications de cavitation, où le nombre de Mach atteint des valeurs de 0.5, la distribution de particules doit être corrigée. Cela est réalisé grâce à la fonctionnalité ALE. Le modèle compressible a été validé à l’aide de configurations monodimensionnelles, comme le cas du tube à choc pour des écoulements monophase et multiphases. L’effondrement de la bulle près d´une paroi a été abordé comme le mécanisme fondamental qui produit des dégâts. Son comportement général se caractérise par la formation d’un micro jet d’eau et par l’effondrement de la bulle sur elle-même. Le phénomène est analysé en tenant compte des principaux paramètres qui le régissent, comme la distance initiale entre le centre de la bulle et la paroi (H0), la taille de la bulle (R0) et le taux de pression qui entraîne l’effondrement (pw/pb). Il est démontré que l’intensité de l’effondrement dépend principalement du rapport de pression entre le liquide et la bulle (pw/pb). De plus, quatre indicateurs, comme la pression en paroi, l’impulsion, la pression du coup de bélier et la vitesse du micro jet d’eau, servent à déterminer le chargement. Cette analyse indique qu’une bulle initialement située à une distance inférieure à H0/R0 = 2 présente un haut potentiel d’endommagement. Afin de prédire cet endommagement, la mécanique du solide est analysée à l’aide de simulations d’interaction fluide-structure. On obtient que le matériau réagit aux charges hydrauliques en ayant des zones de compression et de traction. Ceci suggère qu’un mécanisme de fatigue entraîne le phénomène d’endommagement. En plus, on constate que les contraintes les plus importantes sont situées sous la surface du matériau, indiquant que cette zone peut être sujette à une déformation plastiqueHydraulic turbines can experience cavitation, which is a phenomenon occurring when vapor bubbles collapse in the vicinity of the machine’s surface. This phenomenon can lead to negative consequences, such as erosion, that affect the machine’s performance. The compression of a non-condensable gas bubble in water is simulated with the Smoothed Particle Hydrodynamics method following the Arbitrary Lagrange Euler approach (SPHALE), where a compressible and multiphase model has been developed. The model solves the mass, momentum and energy conservation equations of the Euler system using the Stiffened Gas EOS for water and the ideal gas EOS for the non-condensable gas inside the bubble. Both phases are modeled as compressible and the phase change is not considered. The meshless feature of the SPH-ALE method allows the calculation of multiphase flows where the interface is sharply defined. For cavitation applications, where the Mach number reaches values of 0.5, the distribution of particles must be corrected, which is achieved by the ALE feature. The compressible model was validated through monodimensional configurations, such as shock tube test cases for monophase and multiphase flows. The bubble compression close to the wall has been addressed as the fundamental mechanism producing damage. Its general behavior is characterized by the formation of a water jet and by the collapse of the bubble by itself. The phenomenon is analyzed by considering the major parameters that govern the bubble collapse dynamics, such as the initial distance between the bubble center and the wall (H0), the bubble size (R0), and the collapse driven pressure ratio (pw/pb). It is shown that the intensity of the collapse depends mainly on the pressure ratio between the liquid and the bubble (pw/pb). As well, four indicators, such as the pressure at the wall, the impulse, the water-hammer pressure and the water jet velocity, are used to determine the loading. This analysis gives that the bubble initially located at a distance lower than H0/R0 = 2 presents high potential to cause damage. In order to predict the damage due to the bubble collapse, the solid mechanics is analyzed through fluid-structure interaction simulations. It is obtained that the material reacts to the hydraulic loads by having compression and traction zones, suggesting that a fatigue mechanism drives the damage phenomenon. Additionally, it is found that the highest stresses are located below the material surface, indicating that this zone may reach plastic deformation
47
Sigby, Albin. "Förändringsanalys av erosion längs Klarälven". Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-74725.
Testo completoAbstract (sommario):
Klarälven är en av Sveriges längsta älvar och är unik i Skandinavien för sitt karaktäristiska meanderlopp. Det unika i Klarälvens fall är att älvfåran är instängd mellan två bergssidor. Klarälvens meanderlopp innebär erosion och förändringar i älvens lopp. Syftet med studien är att jämföra och analysera hur erosionen längs en sträcka av Klarälven har förändrats över tid. Underlaget består av en historisk karta från 1883 samt ortofoton från 1961 och 2014. Studien är avgränsad till en 25 km lång sträcka norr om Ekshärad i Värmland. Metoder som används omfattar georeferering av den historiska kartan samt skärmdigitalisering av samtliga data. Därefter granskades och jämfördes resultaten genom överlagringsanalys uppdelat i två perioder samt alla perioder på en gång. Resultatet visar att omfattande erosion och avlagring har skett. I älvens ytterkurvor där vattnets hastighet är som högst har störst erosion skett och i innerkurvorna där vattnet rinner långsammare har det eroderade materialet avlagrats. De största skillnaderna är uppmätta mellan åren 1883 och 1961. Men erosionsförändring i mindre skala har skett även mellan 1961 och 2014.River Klarälven is one of Sweden's longest rivers and is unique in Scandinavia because of its characteristic meander course. The uniqueness in the case of Klarälven is that the riverbed is trapped between two mountain sides. The meandering course of Klarälven means major changes in its path due to extensive erosion along some reaches. The purpose of this study is to compare and analyze how some reaches of River Klarälven have changed over time. The data consists of a historical map from 1883 as well as orthophotos from 1961 and 2014. The study is limited to a 25 km meandering reach north of the town Ekshärad in northern Värmland. Methods involved are georeferencing of the historical map and screen digitizing of all data. Subsequently, the results were reviewed and compared by overlay analysis divided into two periods and all periods at once. The result shows that extensive erosion and deposit have taken place. In the river's outer curves where the velocity of the water is highest is also the place where most erosion occurs. In the inner curves where the water velocity is slower, the eroded material is deposited. The largest differences were measured between the years 1883 and 1961. However, erosion changes on a smaller scale also occurred between 1961 and 2014.
48
PIGAZZINI, ILARIA. "Evaluating and Detecting Architecture Erosion". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2022. http://hdl.handle.net/10281/365009.
Testo completoAbstract (sommario):
Un'architettura software è erosa (o degradata) se mostra una progressiva perdita di integrità strutturale a causa di violazioni dei principi di progettazione. I sistemi erosi soffrono di Architectural Technical Debt (ATD), lo sforzo aggiuntivo richiesto agli sviluppatori per gestire i difetti causati dall'erosione. Un sintomo dell'accumulo di ATD è la presenza di Architectural Smells (AS), decisioni di software design che hanno un impatto negativo sulla qualità interna del sistema software. I sistemi affetti da AS soffrono di maggiori costi di manutenzione e sono più difficili da evolvere. Questa tesi indaga sei diversi tipi di AS che violano diversi principi di design in progetti Java monolitici Open-Source e industriali. Identifichiamo gli AS con il nostro strumento, Arcan, e introduciamo la sua nuova estensione per la rappresentazione dei software concerns. Discutiamo poi gli AS dal punto di vista dei professionisti, cercando di riassumere come gli AS sono percepiti e validando i risultati di Arcan. Riportiamo anche i risultati dei nostri studi empirici riguardanti l'evoluzione e la correlazione di AS e ATD. Infine, presentiamo i nostri primi risultati riguardanti la migrazione e la manutenzione di architetture a microservizi, con particolare attenzione al rilevamento degli odori dei microservizi.A software architecture is eroded (or degraded) if it shows a progressive loss of structural integrity due to design principle violations which leads to the deviation of the implemented architecture from the intended architecture. Eroded systems suffer from Architectural Technical Debt (ATD), the additional effort required by developers to manage the shortcomings caused by the erosion. A symptom of the accumulation of ATD is the presence of Architectural Smells (AS), design decisions that impact negatively on the internal system quality. Systems affected by AS suffer from higher maintenance costs and are harder to evolve. This thesis investigates six different types of AS violating different design principles in Open-Source and industrial monolithic Java projects. We identify AS with our tool, Arcan, and introduce its new extension for the representation of software concerns. We then discuss AS from the point of view of practitioners, trying to summarise how AS are perceived and validating Arcan results. We also report the results of our empirical studies concerning AS and ATD evolution and correlation. Finally, we present our first results concerning the migration and maintenance of microservices architectures, with a focus on the detection of microservices smells.
49
Mazur, Rogério Lago [UNESP]. "Análise do desgaste erosivo por partícula sólida em superligas à base de níquel". Universidade Estadual Paulista (UNESP), 2004. http://hdl.handle.net/11449/97116.
Testo completoAbstract (sommario):
Made available in DSpace on 2014-06-11T19:28:35Z (GMT). No. of bitstreams: 0
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Universidade Estadual Paulista (UNESP)
As superligas à base de níquel são aplicadas nos mais diversos e complexos sistemas de engenharia, entretanto há poucos dados sobre o comportamento erosivo destas superligas frente ao impacto de particulas sólidas em um fluxo gasoso. A erosão por partícula sólida é um fenômeno complexo e caracteriza-se pela deformação e remoção de material durante o impacto das partículas, gerando elevadas temperaturas. As superligas à base de níquel Nimonic 80 A e Inconel 600, são materiais que possuem ótimas propriedades mecânicas emelevadas temperaturas, por este motivo, as suas características quanto à erosão em temperatura ambiente, serão medidas e analisadas, em vista da perda das propriedades mecânicas dos aços em temperaturas mais altas durante o impacto das partículas. Os ensaios de erosão foram realizados em um dispositivo do tipo jato de impacto ar-areia, onde as partículas erosivas forma introduzidas em um sistema à alta pressão e aceleradas ao longo de um bocal antes de impactar a superfície do material, permitindo simular os principais parâmetros do desgaste erosivo. Os ensaios realizados apresentaram pequenas diferenças para todosângulos de impacto testados (15°, 30°, 60°, 90°), porém os intervalos de confiança se superpõem para quase todos eles apesar da marcante diferença entre as propriedades mecânicas das superligas Nimonic 80 A e Inconel 600, não sendo possível estabelecer alguma correlação com a resistência à erosâo.
The Ni-base superalloys are applied in several and complexest engineering systems, however there are few data about the erosive behaviour of these superalloys regarding the impact of solid particles in a gaseous flow. The solid particle erosion is a complex phenomenon and it is characerized by the deformation and material removal during the impact of the particles generating high temperatures. The Ni-basesuperalloys Nimonic 80 A and Inconel 600, have excellent mechanical properties in high temperature, by this reason, theirs characteristics in erosion at room temperature, will be measured and analyzed, in view of the losses of the mechanical properties of the steels in higher temperatures during the impact of the particles. The erosion tests have been performed in air-sand jet impingement device, where the erosive particles were introduced in a system with high pressure and accelerated along a nozzle before impact the surface of the material, allowing to simulate the main parameters of the erosion wear. The results showed small differences for all impact angles tested (15°, 30°, 60°, 90°), however the reliable intervals have been superimpsed for almost all of them, in spite of the great differences among the mechanical properties of the superalloys Nimonic 80 A and Inconel 600, it was noto possible to establish some correlation with the erosion resistance.
50
Campos, Camila Jorge Moretti de [UNESP]. "Avaliação da erodibilidade pelo método Inderbitzen em solo não saturado da região de Bauru - SP". Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/115945.
Testo completoAbstract (sommario):
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Esta dissertação de mestrado apresenta resultados acerca da avaliação da erodibilidade de um solo não saturado localizado em uma área urbana de Bauru-SP afetada por um processo erosivo. O processo erosivo em questão se desencadeou devido a intervenção antrópicas no local sem devidas precauções para amenização do impacto causado, como o desmatamento, impermeabilização do solo e construção de loteamentos residenciais de alto padrão com projetos inadequados e falta de obras de infra-estrutura de drenagem. A avaliação do fenômeno se due por meio de levantamento bibliográfico do tema, principalmente do histórico de informações disponíveis acerca do processo erosivo, observações de campo e ensaios de laboratório: caracterização, erodibilidade através do Inderbitzen e cisalhamento direto, além de ensaios para medida e controle de sucção das amostras, afim de se obter a curva de retenção e valores de comparação através deste parâmetro para os ensaios de erodibilidade. Todos os ensaios foram realizados em amostras de dois locais distintos ao longo do processo erosivo. Os solos da região são residuais de Arenito, caracterizados como areias finas a médias argilosiltosas. Os resultados dos ensaios de erodibilidade através do Inderbitzen mostraram grande quantidade de solo carreada pelo escoamento hídrico superficial, sendo maiores taxas ocorridas no solo do Local A. A perda de solo variou em sua quantidade de acordo com a inclinação da rampa. Assim, quanto maior a inclinação da rampa, maior a quantidade de perda do solo, que demonstra a susceptibilidade deste solo à erosão hídrica em locais com a topografia mais acentuada. Em geral, a maior taxa de erodibilidade ocorreu no tempo de 5 minutos, com uma tendência à estabilização nos tempos seguintes. Essa tendência ocorreu nos diferentes tipos de amostras utilizadas, exceto para a amostra com sucção de 0 kPa, que apresentou o pico de maior perda de...
This master's dissertation reports an assessment of the erodibility of unsaturated soil located in an urban are affected by erosion in Bauru, São Paulo. The erosion process in question was triggered by human interference at the site, which was undertaken without proper precautions to reduce the resulting impact, which included deforestation, sealing of the soil, use of inadequate plans to construct high-end residential subdivisions, and lack of drainage infrastructure. The phenomenon was assessed by a survey of the literature-principally historical information related to the erosion process - field observations, and laboratory tests: characterization, erodibility as assessed by the Inderbitzen and direct shear tests, and tests to measure and monitor soil suction of the samples in order to obtain the soil-water retention curve and comparison values through this parameter for the erodibility tests. All tests were performed on samples from two distinct locations throughout the erosion zone. The soils from the region are remnants of sandstone and are characterized as clay-sit soils with fine to medium sand. The Inderbitzen tests showed a large amount of soil carried away by water flow, with higher rates registered for the soil from Location A. Soil loss varied in quantify according to the slope of the ramp. Consequently, the greater the slope of the ramp, the greater the amount of soil loss, which demonstrates the susceptibility of this soil to erosion resulting from water in places with more pronounced topography. In general, the highest rate of erodibility occurred at 5 min, with a tendency to stability thereafter. This tendency occurred in the different types of samples used, except for the sample with soil suction of 0 KPa, which showed the greatest soil loss at 1 min. This demonstrates the influences of soil suction in the first moments of contact with the water flowing in the Inderbitzen test. The direct shear tests showed that the...