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He, Yuxin. "Crop residue management and its impacts on soil properties." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/19043.
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Doctor of PhilosophyAgronomy
DeAnn R. Presley
Crop residue removal for livestock feeding and biofuel production at large scales must be evaluated to assess impacts on soil productivity and properties. Among all the potential negative impacts, wind erosion is a major concern in the central Great Plains. We conducted an on-farm study from 2011 to 2013 by removing crop residue at five levels (0, 25, 50, 75, and 100%) to determine the effects of crop residue removal on soil wind erosion parameters such as dry aggregate size distribution including soil wind erodible fraction (EF <0.84 mm aggregates), geometric mean diameter (GMD) and geometric standard deviation (GSD), dry aggregate stability, and soil surface roughness. The sub-model of Wind Erosion Prediction System (WEPS) developed by the USDA-ARS, Single-event Wind Erosion Evaluation Program (SWEEP) is a stand-alone companion software package that can be applied to simulate soil loss and dust emission from a single windstorm event. We applied measured data (i.e. EF, GMD, GSD, and roughness) to SWEEP for predicting wind velocity that can initiate wind erosion and soil loss under each crop residue removal condition with wind velocity at 13 m sˉ¹. The threshold wind velocity to initiate wind erosion generally decreased with increase in crop residue removal levels, particularly for residue removal >75%. The total amount of soil loss in 3 hours ranged from about 0.2 to 2.5 kg mˉ² and depends on soil condition and crop residue cover. On the other hand, high-yielding crops can produce abundant crop residue, which then raises the question that if a farmer wants to reduce residue, what could they do without removing it? The application of fertilizer on crop residue to stimulate microbial activity and subsequent decomposition of the residue is often debated. We conducted wheat straw decomposition field experiments under different fertilizer rates and combinations at three locations in western Kansas following wheat harvest in 2011 and 2012. A double shear box apparatus instrumented with a load cell measured the shear stress required to cut wheat straw and photomicrography was used to measure the cross-sectional area of wheat straw after shearing. Total C and N were also analyzed. The fertilizer rate and timing of application during summer 2012 and Fall 2013 at the Hays site had impacts on wheat straw shear stress at break point. Across site years, earlier (fall) fertilizer application generally resulted in lower remaining aboveground biomass as compared to a spring application. Multivariate and linear regressions suggested that N and C:N ratio partially explain the results observed with respect to treatment effects on winter wheat residue decomposition.
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Dam, Rikke Friis. "Impacts of long term tillage and residue practices on selected soil properties." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=78344.
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A two year study was initiated in 2001 on a 2.4 ha site of mostly St. Amable loamy sand and shallow loamy sand at the Macdonald Campus Research Farm. This study sought to assess the effects of long term tillage and residue practices on soil physical properties and to relate these properties to their influence on total carbon, total nitrogen and soil microbial biomass-carbon. The site was set up as a factorial experiment with three tillage practices (no till---NT; reduced till---RT; and conventional till---CT) and two residue practices (with residue (grain corn), +R; without residue (silage corn), -R). Soil physical properties measured were bulk density, macroporosity at -6 kPa, saturated hydraulic conductivity (Ksat ), dry aggregate distribution, soil moisture and soil temperature. Wheel versus non-wheel track bulk density was also determined in the NT plots. Total porosity, soil water characteristic curves and pore volume distribution were derived from field samples. Crop yield was also assessed. Tillage alone had an effect on total porosity, bulk density, pore diameter and macroporosity. No individual physical property was significantly affected by the residue treatments; however, the tillage and residue interaction was significant for Ksat, soil moisture and soil temperature. Dry aggregate distribution was not affected by either tillage, residue or the combination of the two. Tillage affected total carbon and total nitrogen in the 0--0.10 m depth. Soil microbial biomass-carbon was affected by residue inputs. Total carbon and nitrogen were influenced by the bulk density, but none of the other soil physical properties. Soil microbial biomass-carbon was not influenced by any of the physical properties. Tillage and residue practices had no significant effect on crop yield for either year.
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Ducamp, Fernando Arriaga Francisco J. "Effect of rye residue on soil properties and nitrogen fertiization of cotton." Auburn, Ala, 2008. http://hdl.handle.net/10415/1532.
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Wilkins, Deborah K. "Studies of protein denaturation and aggregation." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325146.
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Senaputra, Alexander. "The impact of desilication products on the flocculation and sedimentation properties of bauxite residue." Thesis, Curtin University, 2014. http://hdl.handle.net/20.500.11937/1522.
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In the Bayer processing of bauxite, dissolved silica re-precipitates as aluminosilicates or desilication products (DSPs) that adversely affect residue separation by flocculation and thickening prior to product precipitation. DSP was shown to form at the surface of hematite, impacting upon the extent, efficiency and mechanism of aggregation with a number of different polymer reagents. Real-time measurement of aggregate properties provided new insights on fines capture. The practical implications for full-scale feedwell flocculation were explored.
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Ribeiro, Bruno. "Study of Effective Use of Sugarcane Residue as Eco-friendly Construction Materials for Disaster Prevention Structures." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263808.
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付記する学位プログラム名: 京都大学大学院思修館京都大学
新制・課程博士
博士(総合学術)
甲第23347号
総総博第20号
京都大学大学院総合生存学館総合生存学専攻
(主査)教授 山敷 庸亮, 教授 山本 貴士, 教授 寶 馨, 教授 齋藤 敬
学位規則第4条第1項該当
Doctor of Philosophy
Kyoto University
DFAM
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Turek, Iga Anna. "The effect of microwave extraction on the chemical composition and the antioxidant properties of the coffee residue." Master's thesis, Universidade de Aveiro, 2010. http://hdl.handle.net/10773/3523.
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Mestrado em Biotecnologia AlimentarO presente trabalho, pretendeu estudar o efeito da extracção em microondas na composição química do resíduo de café. As analises ao resíduo de café incluíram: conteúdo em açucares e aminoácidos (GC-FID), conteúdo em gordura (extracção em Soxhlet), composição volátil do óleo do resíduo de café (GCxGC), e capacidade antioxidante (espectrofotometria) do óleo, supernadantes, e resíduos após as extracções com microondas. As extracções com microondas foram efectuadas em ciclos de 8 minutos atingindo uma temperatura de 200°C. Ambos os supern adantes e resíduos for examinados pelo seu rendimento em massa, conteúdo e composição em polissacarídeos e aminoácidos, conteúdo em óleo e capacidade antioxidante. Os rendimentos obtidos por extracção com microondas atingiram 20-25% em massa, da qual cerca de 41-63% são açucares solúveis em água. A composição em polissacarídeos alterou-se do primeiro para o segundo ciclo de extracção, sendo que as arabinogalactanas são preferencialmente extraídas durante o primeiro ciclo, enquanto que no segundo ciclo se obtém uma mistura de arabinogalactanas e galactomananas. O resíduo de café insolúvel (79 %, w/w) continua rico em polissacarideos (46- 55% w/w), sendo enriquecido em glucose ao longo dos ciclos. A maioria dos aminoácidos continuam no resíduo, mesmo após os tratamentos com microondas. Também a composição permanece inalterada, com excepção para as percentagens dos ácidos glutâmico e aspártico, cuja quantidade aumenta significativamente após os tratamentos. A maioria do óleo remanesce no resíduo após os tratamentos. Uma elevada capacidade antioxidante (AOC) foi encontrada no óleo extraído do resíduo de café inicial, supernadantes, e extractos de resíduo finais. O óleo extraído após o primeiro ciclo de extracção apresenta uma diminuição da sua AOC quando comparada com a actividade do resíduo inicial, sendo detectada uma redução considerável após o segundo ciclo, ainda assim com valores superiores quando comparados com os valores de AOC apresentados por amostras comerciais de óleo de azeitona. Todos os supernadantes apresentam uma AOC superior a qualquer um dos resíduos, incluindo o resíduo inicial e os resíduos obtidos após os vários tratamentos com microondas. Quando comparados com o resíduo inicial de café antes de qualquer tratamento com microondas, ao qual corresponde uma actividade de 15 gsoluto/ Lsolução, o supernadante obtido apos o primeiro ciclo de extracção apresentou um AOC de 5 gsoluto /Lsolução, reduzindo a sua actividade para metade após o segundo ciclo. Foram identificados ~170 compostos no espaço de cabeça do óleo obtido a partir do resíduo de café, incluindo furanos e pirazinas, compostos identificados como sendo responsáveis pelo aroma semelhante a café. Ainda no espaço de cabeça do óleo foram identificados novos compostos os quais são: 1-metil-ciclopentanol; fenilacetaldeído; propanoato de 2-furano metanol; acetato de 2-furano metanol, 2-acetil-3-metilpirazina; 1-etil-1Hpyrrole- 2-carboxaldeído; 2-pineno; (1S)-2,6,6-trimetil biciclo(3,1,1)heptano-2- eno; p-xileno;1-fenil-etanona; 5-metil-2(3H)-furanona.
The present work, studied the effect of microwave extraction on the chemical composition of the coffee residue. The analysis of the coffee residue included: sugars and amino-acids content (by GC-FID), fat content (by Soxhlet extraction), coffee residue oil volatile composition (GCxGC), and the antioxidant capacity (by spectrophotometry) of the oil, supernatants, and residues after microwave extractions. The microwave extractions were performed in two 8-minutes cycles reaching 200°C. Both supernatants and residues were examined for their mass yield, polysaccharides and amino acids content and composition, fat content and antioxidant capacity. The microwave extraction yields about 20-25% of mass, of which 22-38% are water soluble sugars. The polysaccharides composition changes from the first to the second cycle, being the arabinogalactans preferentially extracted during the first microwave cycle, and a mixture of arabinogalactans and galactomannans extracted to supernatant during the second cycle. The insoluble coffee residue (79 %, w/w) remains rich in polysaccharides (20- 39%, w/w), being enriched in glucose over the cycles. Most of the amino acids remain in the residues, even after the microwave treatments. The composition remains almost unchanged, with the exception for the percentage of glutamic and aspartic acid, which rise significantly after the treatments. Most of the oil is also maintained in the residue after the treatments. The oil extracted from the coffee initial residue, supernatant, and final residue extracts, all have high antioxidant capacity (AOC). The oil obtained after the first cycle of microwave extraction slightly lowered its AOC when compared to the initial activity, while a considerably reduction was detected after the second cycle, which is still higher that the AOC showed by commercial olive oil samples. The supernatants all have higher AOC when compared to the residues, both the initial as the ones after the microwave treatments. When compared to the initial residue, which correspondent EC50 is 15 gsolute/Lsolution before microwave extraction, the supernatant after the first microwave extraction cycle has an AOC of 5 gsolute/Lsolution, reducing its activity to half after the second microwave cycle. In the headspace of the oil obtained from the coffee residue ~170 compounds were identified, including furans and pyrazines, which are compounds identified as being responsible for the coffee-like aroma. Among the new compounds, which were found in head-space of coffee oil are: 1-methyl-cyclopentanol; phenyl acetaldehyde; 2-furanmethanol, propanoate; 2-furanmethanol, acetate; 2-acetyl-3-methylpyrazine; 1-ethyl-1H-pyrrole-2carboxaldehyde; 2-pinene; (1S)- 2,6,6-trimethylbicyclo(3,1,1)hept-2-ene; p-xylene; 1-phenyl-ethanone; 5-methyl- 2(3H)-furanone.
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Barbhniya, Salim Ahmed. "An Investigation on the Use of Seawater-Neutralised Bauxite Refinery Residue (Bauxsol TM) on Properties of Structural Concrete." Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517209.
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Subedi-Chalise, Kopila. "Impacts of Crop Residue and Cover Crops on Soil Hydrological Properties, Soil Water Storage and Water Use Efficiency of Soybean Crop." Thesis, South Dakota State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10265200.
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Cover crops and crop residue play a multifunctional role in improving soil hydrological properties, soil water storage and water use efficiency (WUE). This study was conducted to better understand the role of crop residue and cover crop on soil properties and soil water dynamics. The study was conducted at the USDA-ARS North Central Agricultural Research Laboratory, located in Brookings, South Dakota. Two residue removal treatments that include low residue removal (LRR) and high residue removal (HRR) were established in 2000 with randomized complete block design under no-till corn (Zea mays L.) and soybean (Glycine max L.) rotation. In 2005, cover crop treatments which include cover crops (CC) and no cover crops (NCC) were integrated into the overall design. Soil samples were collected in 2014, 2015 and 2016. Data from this study showed that LRR treatment resulted in lower bulk density (BD) by 7 and 9% compared to HRR in 2015 and 2016, respectively, for 0-5 cm depth. Similarly, LRR treatment significantly reduced soil penetration resistance (SPR) by 25% in 0-5 cm depth compared with HRR treatment. In addition to this, LRR treatment significantly increased soil organic carbon (SOC) concentrations and total nitrogen (TN) by 22 and 17%, respectively, in 0-5 cm. Similarly, CC treatment resulted in lower BD and SPR by 7% and 23%, respectively, in 0-5 cm depth in 2015 compared with NCC treatment. The LRR significantly increased soil water infiltration by 66 and 22% compared to HRR in 2014 and 2015, respectively. Similarly, the CC treatment significantly increased infiltration by 82 and 22% compared to the NCC in 2014 and 2015, respectively. The significant impact of a crop residue was observed on soil water retention (SWR) in 2014 and 2015 for the 0-5 cm depth. The LRR and CC treatments increased the soil volumetric moisture content (VMC) and soil water storage (SWS) on the surface 0-5 cm depth. However, the trend was not always significant during the growing season. The CC treatment significantly impacted the soybean yield by 14% and WUE by 13% compared with NCC treatment. Some interaction of residue by cover crops was observed on BD, SPR, VMC, and SWS, which showed that the use of cover crops with LRR can be beneficial in improving the soil properties.
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Landzela, Besule. "Effects of BT Maize (MON810) crop and its residues on selected soil biological properties and N and P release in a sandy loam soil from Alice, Eastern Cape, South Africa." Thesis, University of Fort Hare, 2013. http://hdl.handle.net/10353/d1007542.
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There are apprehensions that genetic modification of maize with Bacillus thuringiensis (Bt) may have negative effects on soil biodiversity, ecosystem processes and functions. This study aimed at determining the effect of Bt maize crop, Bt maize residues and its genetic modification on microbial biomass carbon (MBC), selected enzyme activities, vesicular arbuscular mycorrhizal (VAM) fungi and N and P release patterns. The study was conducted under field, glasshouse and laboratory conditions. In 2010/2011 season, four maize cultivars; DKC 61-25B (Bt), DKC 61-24 (non-Bt), PAN 6Q-321B (Bt) and PAN6777 (non-Bt) were planted. Determination of MBC, enzyme activities and fungal spore count was done at 42, 70, and 105 days after planting (DAP). A loam soil amended with Bt or non-Bt maize leaf residues from a study of 2009/2010 season was incubated to investigate effects of Bt maize residues on MBC and soil enzyme activities. Leaf residues of Bt and non-Bt maize cultivars (DKC 61-25B, DKC 61-24, PAN 6Q-321B and PAN6777) were used and soil without residues was used as a control. Samples were collected at 7, 28 and 56 days of incubation (DOI). An incubation study was also carried out in the laboratory to determine the effect of Bt maize residues (i.e. leaf, stem and root) and its genetic modification on N and P release patterns. Residues of DKC 61-25B, DKC 61-24, PAN 6Q-321B and PAN6777and soil without residues as a control were incubated in the laboratory. After destructive sampling at 0, 7, 14, 28, and 56 DOI, N in the form of NH4-N and NO3-N and P mineralisation were determined. Amendment of soil with residues enhanced MBC (p < 0.05) at all the sampling dates. For example MBC increased from 95 in the control to 146.3 mg/kg in the DKC 61-25B treatment at the end of the glasshouse trial. In the field DKC 61-25B had 9.1 mg/kg greater MBC than DKC 61-24, while PAN 6Q-321B had 23.9 mg/kg more MBC than PAN6777 at the end of the trial. However, no differences (p < 0.05) were observed in enzyme activities under field and glasshouse conditions except for dehydrogenase that had greater activity where DKC 61-25B and PAN 6777 were grown. There were no differences between the type of residues (Bt and non-Bt) on enzyme activities tested. However, differences were observed among the sampling dates. No effects of Bt maize crop on fungal spore count were observed. Similarly no differences were observed in leaf, stem and root tissues composition between Bt and non-Bt maize cultivars. Net N and P mineralisation from Bt maize cultivars did not differ from that of non-Bt maize cultivars. However, differences were observed among the cultivars. The results of this study suggested that Bt maize with Bt MON810 event can be grown in the central region of the Eastern Cape (EC), South Africa without affecting MBC, soil enzyme activities, VAM, and release of N and P nutrients from its residues.
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Figueiredo, Juliana Dias de Castro. "Aplicação de uma fração do resíduo do shredder na fabricação de blocos cerâmicos estruturais." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/163457.
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O objetivo deste trabalho é avaliar a incorporação de uma fração cuja fração granulométrica é menor que 2mm do resíduo do Shredder proveniente de uma indústria siderúrgica ao processo de fabricação de blocos cerâmicos estruturais de uma fábrica de cerâmica vermelha. As variáveis analisadas foram: dimensões, propriedades de resistência à compressão, absorção de água e quanto às questões ambientais pela análise de lixiviação e solubilização segundo a NBR 10.004 (ABNT, 2004). Foi realizado processamento do resíduo do Shredder em uma fração menor que 2mm e realizada a incorporação de uma dosagem de 10% e 20% deste material no processo industrial de uma cerâmica de produção de blocos estruturais. Foram avaliadas as propriedades de qualidade e quanto às questões ambientais. Analisando os resultados constatou-se que tanto o bloco cerâmico padrão quanto aos protótipos contendo 10% e 20% de resíduo atendem os limites normativos para resistência à compressão e para absorção de água. Na análise dimensional, somente o protótipo contendo 10% de resíduo atende todos os parâmetros quanto os requisitos normativos.Pelas análises de lixiviado e solubilizado, concluiu-se que tanto o bloco cerâmico estrutural padrão quanto ao protótipo contendo 20% de resíduo são classificados como Classe II A- não inerte. É possível afirmar que a fração menor que 2mm do resíduo do Shredder pode ser utilizada junto à massa cerâmica como matéria-prima para fabricação de blocos cerâmicos estruturais.The goal of this work is to evaluate the incorporation of a fraction smaller than 2 mm of the Shredder Residue from a steel industry into a manufacturing process of structural bricks in a red ceramic factory. Evaluate the quality of results as the compressive strength properties, water absorption and environmental issues as leaching and solubilization analysis according to NBR 10.004 (ABNT, 2004). The Shredder Residue in a fraction smaller than 2mm was incorporated in dosages of 10% and 20% with the clay in the industrial process of a ceramic which produces structural blocks. The quality properties and the environmental issues were analyzed and the results was that both brick pattern block and the prototypes containing 10% and 20% residue meet regulatory limits for compressive strength and water absorption. The analysis of leached and solubilized concluded that both the brick pattern and the prototype containing 20% of waste are classified as Class II A – non inert residue. It is possible to say that the fraction smaller than 2mm of Automotive Shredder Residue can be used with the clay as raw material for the manufacture of structural ceramic blocks.
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Nafi, Eeusha [Verfasser]. "Interactive tillage & crop residue management effects on soil properties, crop nutrient uptake & yield in different weathered soils of West Africa : measurements, modelling & scenario simulations / Eeusha Nafi." Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://d-nb.info/1235525945/34.
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Dultra, Eduardo Jorge Vidal. "Incorpora??o de cinzas da casca de caf? na produ??o de placas cer?micas para revestimento." Universidade Federal do Rio Grande do Norte, 2010. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15610.
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Previous issue date: 2010-01-12Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
Brazil is the world s leading coffee producer. In 2008, 45.99 million of 60 kg bags of benefited coffee were produced. In the process of improvement 50% is grain and 50% is husk, thus, 1.38 million tons of coffee husk are produced annually. The husk is used as combustible in the drying and improvement ovens in the coffee farms, generating ash as residue. These ashes contain a high concentration of alkaline metals and earth metals, mainly K2O and CaO. This work studies the use of this residue in the ceramic tiles industry, as fluxing agents in substitution to the feldspar. Ten mixtures with equal ratios of clay and kaolin, proceeding from Bahia and the residue (varying from 30 to 5%) were defined and produced in uniaxial tool die of 60x20mm with approximately 5 mm of thickness and 45MPa compacting pressure. The samples were fired in four different temperatures: 1100 ?C, 1150 ?C, 1185 ?C and 1200 ?C during 60 minutes and characterized by means of X-ray fluorescence, X-ray diffraction, gravimetric thermal analysis and differential thermal analysis. The results of water absorption, apparent porosity, linear shrinkage, XRD, dilatometry, flexural strength and SEM were also analysed. The test specimen with addition of 10% of ash fired in 1200 ?C resulted in 0.18% water absorption and 40.77 MPa flexural strength, being classified as porcelain stoneware tiles according to ABNT, UNI and ISO norms
O Brasil ? o maior produtor mundial de caf?. Em 2008 foram produzidas 45,99 milh?es de sacas, de 60 Kg, de caf? beneficiado. No processo de beneficiamento 50% ? gr?o e 50% ? casca. Assim, 1,38 milh?es de toneladas de cascas de caf? s?o produzidas anualmente. A casca ? utilizada como combust?vel nos fornos de secagem e beneficiamento nas fazendas de caf?, gerando uma cinza como res?duo. As cinzas da casca de caf? apresentam altas concentra??es de metais alcalinos e alcalinos-terrosos, principalmente K2O e CaO. Este trabalho estuda a utiliza??o deste res?duo na ind?stria de placas cer?micas para revestimentos, como fundente, em substitui??o ao feldspato. Foram definidas 10 formula??es com iguais propor??es de argila e caulim provenientes da Bahia, e o res?duo (variando de 30 a 5%), e confeccionados corpos-de-prova em matriz uniaxial de 60x20mm com aproximadamente 5 mm de espessura, com press?o de compacta??o de 45Mpa. As amostras foram sinterizadas em quatros patamares de temperatura, 1100 ?C, 1150 ?C, 1185 ?C e 1200 ?C durante 60 minutos. Foram realizados ensaios para caracteriza??o das mat?rias-primas por fluoresc?ncia de raios-X, difra??o de raios-X, AG, ATD e ATG e analisados os resultados de absor??o de ?gua, porosidade aparente, retra??o linear, DRX, an?lise dilatom?trica, resist?ncia ? flex?o e MEV. Os corpos de prova com adi??o de 10% da cinza e sinterizados a 1200 ?C obtiveram resultados de absor??o de ?gua de 0,18% e resist?ncia ? flex?o de 40,77 MPa, o que segundo as normas ABNT, UNI e ISO podem ser classificados como gr?s porcelanato
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Machado, Tercio Graciano. "Estudo da adi??o de res?duo de scheelita em matriz cer?mica: formula??o, propriedades f?sicas e microestrutura." Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12813.
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Previous issue date: 2012-11-23Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
Extractivism mineral is considered an activity highly degrading, due to the large volume of material that he moves in the form of ore and residues. The vast majority of mining companies do not show any technology or economically viable application that will allow the recycling of mineral residue, these being launched in areas receiving located the "open skies" degrade the environment. In Rio Grande do Norte to the production of ceramic red restricts their activities to the production of products such as: solid bricks, ceramic blocks, tiles, among others. Seeking to unite experiences and technical information that favor sustainable development, with important benefits to the construction sector and civil society in general, the present work studies the incorporation of the residue of scheelite in ceramic matrix kaolinitic, coming from the municipality of Boa Sa?de - RN, in percentage of 5 %, 10 %, 20 %, 30% 40% and 50 %, by evaluating its microstructure, physical properties and formulation. The raw materials were characterized through the trials of X ray fluorescence, Diffraction of X rays, Differential Thermal Analysis and Termogravimetric Analysis. The samples were formed and fired at temperatures of 850o, 900o, 1000o, 1050o, 1100o, 1150o and 1200 oC, with isotherm of 1 hour and heating rate of 10 oC/min. Assays were performed technological of loss to fire, Water Absorption, Apparent Porosity, Apparent Density, Mass Loss in Fire and Bending Resistance; in addition to the Scanning Electron Microscopy, analyzing their physical and mechanical properties. The use of residue of scheelite in ceramic mass kaolinitic provided a final product with technological properties that meet the technical standards for the production of bricks and roofing tiles, with the percentage of 20% of waste that showed the best results
O extrativismo mineral ? considerado uma atividade altamente degradante, devido ao grande volume de material que ele movimenta em forma de min?rio e res?duo. A grande maioria das empresas mineradoras n?o apresenta nenhuma tecnologia ou aplica??o economicamente vi?vel que permitam a reciclagem do res?duo mineral, sendo estes lan?ados em ?reas de recebimento localizadas a c?u aberto , degradando o meio ambiente. No Rio Grande do Norte a produ??o de cer?mica vermelha restringe suas atividades ? produ??o de produtos como: tijolos maci?os, blocos cer?micos, telhas, dentre outros. Buscando unir experi?ncias e informa??es t?cnicas que favore?am o desenvolvimento sustent?vel, com importantes benef?cios ao setor da Constru??o Civil e ? sociedade em geral, o presente trabalho estuda a incorpora??o do res?duo de scheelita em matriz cer?mica caulin?tica, proveniente do munic?pio de Boa Sa?de RN, em percentuais de 5%, 10%, 20%, 30% 40% e 50%, avaliando sua microestrutura, propriedades f?sicas e formula??o. As mat?rias-primas foram caracterizadas atrav?s dos ensaios de Fluoresc?ncia de raios X, Difra??o de raios X, An?lise T?rmica Diferencial e An?lise Termogravim?trica. Os corpos de prova foram conformados e queimados nas temperaturas de 850o, 900o, 1000o, 1050o, 1100o, 1150o e 1200 oC, com isoterma de 1 hora e taxa de aquecimento de 10 oC/min. Foram realizados os ensaios tecnol?gicos de Perda ao Fogo, Absor??o de ?gua, Porosidade Aparente, Massa Espec?fica Aparente e Tens?o de Ruptura ? Flex?o; al?m da Microscopia Eletr?nica de Varredura, analisando-se suas propriedades f?sicas e mec?nicas. A utiliza??o de res?duo de scheelita em massa cer?mica caulin?tica propiciou um produto final com propriedades tecnol?gicas que atendem as normas t?cnicas para produ??o de blocos e telhas cer?micas, sendo que o percentual de 20% de res?duo apresentou os melhores resultados
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Mallawa, Arachchi Kumudu. "Residual properties of groups." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ48502.pdf.
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Clapton, J. H. "Residual properties of groups." Thesis, Cardiff University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303866.
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Mallawa, Arachchi Don Kumudu Carleton University Dissertation Mathematics and Statistics. "Residual properties of groups." Ottawa, 1999.
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George, Anthe. "The leaching properties of co-combustion residues." Thesis, Imperial College London, 2005. http://hdl.handle.net/10044/1/12027.
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Pilati, Fernanda. "Análise dos efeitos da borracha moída de pneu e do resíduo de óleo de xisto sobre algumas propriedades mecânicas de misturas asfáticas densas." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/18/18143/tde-14062008-202738/.
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No Brasil, desde o início da década de 1990, vêm sendo desenvolvidas pesquisas sobre aplicação do asfalto-borracha visando tanto a diminuição dos problemas ambientais gerados pelo descarte de pneus inservíveis, como a melhoria das características dos ligantes produzidos. Dentro desse contexto, esta pesquisa teve por objetivo avaliar o desempenho mecânico de oito misturas asfálticas do tipo concreto asfáltico usinado a quente, produzidas com asfaltos convencional e convencional modificado com borracha de pneu e resíduo de óleo de xisto. Quanto ao ligante, foram utilizados 8 tipos, a saber: CAP 30/45 (referência); dois ligantes empregando teores diferentes de borracha moída de pneu; outros dois com teores distintos de resíduo de óleo de xisto e, por fim, mais três com combinações de teores de borracha e de resíduo de óleo de xisto. Os corpos-de-prova empregados nos ensaios foram moldados em cinco teores diferentes de ligantes asfálticos (4,5; 5,0, 5,5; 6,0 e 6,5%). Conseqüentemente, foram realizados ensaios Marshall, resistência à tração, módulo de resiliência e umidade induzida. Com base nos resultados dos ensaios realizados observou-se que tanto a borracha quanto o óleo reduzem a resistência à tração e o módulo de resiliência das misturas, no entanto, na recuperação retardada, os efeitos da borracha e do óleo são antagônicos, diminuindo e aumentando, respectivamente. Ademais, quanto à suscetibilidade à ação da água, as misturas com adição de óleo apresentaram menor suscetibilidade que as misturas com adição de borracha. Além disso, foi observado que todas as misturas estudadas, exceto aquelas com altas concentrações de óleo e de borracha, atenderam os requisitos estabelecidos pelas especificações, para as propriedades analisadas. Todavia, em alguns casos, considerando os efeitos antagônicos do óleo e da borracha, algumas combinações entre ambos podem ser realizadas, com a finalidade de alcançar os níveis desejados para as propriedades do ligante asfalto-borracha e das misturas asfálticas.In Brazil, since the beginning of the 90\'s, have been developed researches on the application of asphalt-rubber seeking the reduction of environmental problems created by the used tires, and the improvement of the characteristics of the produced binder. Taking this into account, the purpose of this research is to evaluate the mechanical performance of eight hot mix asphalt concretes, produced with conventional asphalt and modified asphalt with crumb rubber and shale-oil residue. Eight types of binders were used: CAP 30/45 (reference); two binders using different crumb rubber contents, two with different shale-oil residue contents, and finally three more with the combination of crumb rubber and shale-oil residue contents. The specimens used in the laboratorial tests were compacted in five different binders contents (4.5; 5.0, 5.5; 6.0 e 6.5%). Hence, the tests performed are: Marshall test, indirect tension, resilient modulus and moisture induced. The results showed that the rubber and the shale oil reduce the indirect tension and resilience module of the mixtures, however, on the delayed recover, the effects of the rubber and of the shale oil are opposed, decreasing and increasing it, respectively. Moreover, for the moisture susceptibility, the mixtures with shale-oil residue exhibited less susceptibility to water than those with crumb rubber. Furthermore, all the studied mixtures, except those with high shale-oil residue and rubber concentrations, they got to attend the established requirements for the specifications, for the analyzed properties. Although, in some cases, considering the opposed effects of the shale oil and of the crumb rubber, some combinations between both can be accomplished, with the purpose of reach the levels wanted for the properties of the asphaltrubber binder and the asphalt mixtures. Also regression models were elaborated as for the analyzed properties. The results obtained of modeling were satisfactory.
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Avelino, Keite Anny Rocha. "Estudo da potencialidade da incorpora??o de res?duo de granito e da queima da casca do caf? em cer?mica vermelha." Universidade Federal do Rio Grande do Norte, 2013. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12821.
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Previous issue date: 2013-11-29The industrial production of ornamental rocks and the burning of coffee husk generate waste that is discarded into the environment. However, with the study of the incorporation of these residues in ceramic products, may be found an alternative to reducing environmental impacts and detrimental effects on human health caused by its indiscriminate disposal of waste in nature. Thus, this work aimed to study the addition of ashes of the coffee husk and granite residue in matrix of red ceramic. The raw materials were dry milled and sieved to mesh 100. To characterize the raw materials were carried out analyzes of X-ray diffraction (XRD), X-ray fluorescence (XRF), particle size analysis (PSA), differential thermal analysis (DTA) and thermogravimetric analysis (TG). Six formulations were prepared where the clay content was kept constant (70%wt) and ashes contents and granite residue varied from 10, 15, 20 and 30%. Dilatometrics analyzes were performed at four selected formulations, containing them: 100% clay (A100); 70% clay and 30% ashes (A70C30); 70% clay and 30% granite residue (A70G30); and 70% clay, 15% granite residue and 15% ashes (A70G15C15). The samples were prepared by uniaxial compaction with pressure of 25 MPa, and fired at temperatures of 800?C, 850?C, 900?C, 950?C, 1000?C and 1100?C. Assays were performed to determine the linear shrinkage of burning (LSB), water absorption (WA), apparent porosity (AP), density (D) and tensile bending. Also were performed analyzes of X-ray diffraction (XRD) and scanning electron microscopy (SEM) of the samples fired. The formulations incorporating granite residue and/or ashes reached the required limits of water absorption according to NBR 15270-1 and NBR 15310 and tensile bending according to classical literature (SANTOS, 1989) necessary for the production of tiles and ceramic block for masonry sealing
A produ??o industrial de rochas ornamentais e a queima da casca do caf? geram res?duos que s?o descartados no meio ambiente. Por?m, com o estudo da incorpora??o destes res?duos em produtos cer?micos, poder? ser encontrada uma alternativa para a redu??o dos impactos ambientais e efeitos danosos ? sa?de humana causados pelo seu descarte indiscriminado na natureza. Nesse sentido, este trabalho teve como objetivo estudar a adi??o de cinzas da casca do caf? e res?duo de granito na argila usada para a produ??o de cer?mica vermelha. As mat?rias-primas foram mo?das a seco e peneiradas na malha 100 mesh. Para caracterizar as mat?rias-primas foram realizadas as an?lises de difra??o de raios X (DRX), fluoresc?ncia de raios X (FRX), an?lise granulom?trica (AG), an?lise t?rmica diferencial (DTA) e an?lise termogravim?trica (TG). Foram preparadas seis formula??es onde o teor de argila foi mantido constante (70% em peso) e os teores de cinzas e de res?duo de granito variaram de 10, 15, 20 e 30%. Foram realizadas an?lises dilatom?tricas em quatro formula??es selecionadas, contendo elas: 100% argila (A100); 70% argila e 30% cinza (A70C30); 70% argila e 30% res?duo de granito (A70G30); e 70% argila, 15% res?duo de granito e 15% cinza (A70G15C15). As amostras foram confeccionadas por compacta??o uniaxial com press?o de 25 MPa, e queimadas ?s temperaturas de 800?C, 850?C, 900?C, 950?C, 1000?C e 1100?C. Foram realizados ensaios para determinar a retra??o linear de queima (RLq), absor??o de ?gua (AA), porosidade aparente (PA), massa espec?fica aparente (MEA) e tens?o de ruptura ? flex?o (TRF). Foram realizadas tamb?m an?lises de difra??o de raios X (DRX) e microscopia eletr?nica de varredura (MEV) das amostras queimadas. As formula??es com incorpora??o de res?duo de granito e/ou cinza alcan?aram os limites exigidos de absor??o de ?gua segundo as normas NBR 15270-1 e 15310 e de tens?o de ruptura ? flex?o segundo a literatura cl?ssica (SANTOS, 1989), necess?rios para a produ??o de telhas e blocos cer?micos para alvenaria de veda??o
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SOUZA, WANDER B. de. "Estudo da adição de lama de bauxita em polímero de poli(metacrilato de metila) por meio de polimerizaçao em massa e moldagem em casting." reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11717.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Faxina, Adalberto Leandro. "Estudo da viabilidade técnica do uso do resíduo de óleo de xisto como óleo extensor em ligantes asfalto-borracha." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18137/tde-29052007-170231/.
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Ligante asfáltico e borracha moída de pneus são materiais, na maioria das vezes, de difícil compatibilização, exigindo a adição de produtos químicos que facilitem a dispersão e a incorporação da borracha, como, por exemplo, os óleos extensores. A presente pesquisa tem por objetivo verificar a hipótese de que o resíduo de óleo de xisto, por se tratar de um óleo aromático, presta-se bem como óleo extensor de borracha, permitindo, inclusive, a adição de teores de borracha maiores que os normalmente incorporados aos ligantes asfálticos na ausência de óleos extensores. A tentativa de verificação de tais hipóteses foi efetuada por meio de uma programação laboratorial dividida em duas etapas. A primeira englobou uma investigação sobre o efeito da borracha moída e do resíduo de óleo de xisto sobre características físicas de 27 ligantes asfálticos, a fim de modelar diversas propriedades reológicas desses materiais, tendo como variáveis previsoras as porcentagens de componentes e as variáveis de processo. Na segunda etapa, foram estudados 8 ligantes asfálticos, a fim de obter dados para a validação dos modelos definidos na primeira etapa e também para a modelagem de propriedades não contempladas na primeira fase. Em ambas as fases, o planejamento dos experimentos foi efetuado empregando a técnica estatística de experimentos com misturas. A caracterização física dos ligantes asfálticos foi efetuada por meio de ensaios tradicionais (ponto de amolecimento, penetração e resiliência) e da especificação Superpave (viscosidade aparente, balanço de massa, cisalhamento dinâmico e fluência na flexão), em ligantes virgens e submetidos às práticas de envelhecimento a curto e longo prazos indicadas pela especificação Superpave (RTFOT e PAV). Ensaios de estabilidade à estocagem também foram realizados. Há evidências de que o resíduo de óleo de xisto pode ser empregado como óleo extensor em ligantes asfalto borracha, porém a seleção das concentrações adequadas dos componentes (asfalto, borracha e resíduo de óleo de xisto) depende do monitoramento de propriedades reológicas nas temperaturas de ocorrência dos principais defeitos do pavimento na região de implantação da rodovia.Asphalt binder and crumb rubber from discarded tires are materials that, most of time, are not compatible, requiring the addition of chemical products to facilitate the dispersion and incorporation of rubber particles as, for example, the extender oils. This research aims at evaluating the hypothesis that the shale-oil residue, once it is an aromatic oil, may be used as an extender oil for asphalt-rubber binders, allowing the incorporation of crumb-rubber proportions even higher than those usually added to asphalt binders without extender oils. The effort to verify these hypotheses was made by means of a laboratorial program divided in two steps. In the first step an investigation was carried out to assess the effects of crumb rubber and shale-oil residue on physical characteristics of twenty seven asphalt binders, in order to model rheological properties of these materials, using the component proportions and the process variables as predictor variables. In the second step, eight asphalt binders were studied, to obtain data to validate the original models and to model some properties that were not monitored in the first step. In both steps, the experiment was designed using the statistical technique of experiments with mixtures. The physical characterization of the asphalt binders was performed using traditional tests (softening point, penetration and resilience) and those of Superpave specification (apparent viscosity, mass loss, dynamic shear and flexural creep), with materials in three conditions: virgin, short-term aged (RTFOT) and long-term aged (PAV). Storage stability tests were also performed. There are evidences that the shale-oil residue can be used as an extender oil in asphalt-rubber binders, but the selection of the adequate concentrations of the components (asphalt, rubber and oil) depends on the measurement of rheological properties in the temperatures at which the main pavements distresses occurs in the place the road will be constructed.
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Wain, Nick. "Oxide matrix nanocomposites : residual stresses and mechanical properties." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410715.
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Whitley, Karen Suzanne. "Tensile and Compressive Mechanical Behavior of IM7/PETI-5 at Cryogenic Temperatures." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35944.
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In order for future space transportation vehicles to be considered economically viable, the extensive use of lightweight materials is critical. For spacecraft with liquid fueled rocket engines, one area identified as a potential source for significant weight reduction is the replacement of traditional metallic cryogenic fuel tanks with newer designs based on polymer matrix composites. For long-term applications such as those dictated by manned, reusable launch vehicles, an efficient cryo-tank design must ensure a safe and reliable operating environment. To execute this design, extensive experimental data must be collected on the lifetime durability of PMC's subjected to realistic thermal and mechanical environments. However, since polymer matrix composites (PMC's) have seen limited use as structural materials in the extreme environment of cryogenic tanks, the available literature provides few sources of experimental data on the strength, stiffness, and durability of PMC's operating at cryogenic temperatures.
It is recognized that a broad spectrum of factors influence the mechanical properties of PMC's including material selection, composite fabrication and handling, aging or preconditioning, specimen preparation, laminate ply lay-up, and test procedures. It is the intent of this thesis to investigate and report performance of PMC's in cryogenic environments by providing analysis of results from experimental data developed from a series of thermal/mechanical tests. The selected test conditions represented a range of exposure times, loads and temperatures similar to those experienced during the lifetime of a cryogenic, hydrogen fuel tank. Fundamental, lamina-level material properties along with properties of typical design laminates were measured, analyzed, and correlated against test environments. Material stiffness, strength, and damage, will be given as a function of both cryogenic test temperatures and pre-test cryogenic aging conditions.
This study focused on test temperature, preconditioning methods, and laminate configuration as the primary test variables. The material used in the study, (IM7/PETI-5), is an advanced carbon fiber, thermoplastic polyimide composite.Master of Science
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Östlund, Magnus. "Residual stresses in paperboard and the influence of drying conditions." Doctoral thesis, KTH, Solid Mechanics (Div.), 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-469.
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The drying sequence in the manufacturing process for paperboard involves evaporation of water, primarily from within the fibres. The vapour is then transported out of the web by pressure or concentration gradients. As the moisture transport from the paper web to the ambient is quicker than the moisture transport within the fibre network to the surfaces of the web, moisture gradients develop through the thickness of the web. This work concerns effects on the mechanics of paper drying from the variation in moisture through the relatively thin structures of paper and paperboard.
Distributions of inplane residual stresses through paper materials in the unloaded state after drying are believed to be caused by the varying moisture through the thickness during drying. The distributions in general exhibit compressive stress near the board surfaces and tensile stress in the interior of the board. This may be modified after drying and is also affected by structural variation in the material between different plies of multi-ply paperboards.
The stress development during drying is important because it influences the resulting material properties of the paper and because it can lead to curl, which is a quality problem. The residual stresses themselves are an error source in simulation or evaluation of the mechanical behaviour of paper.
In this work, residual stress distributions in paperboard were determined experimentally, to clarify the mechanisms of residual stress build-up. An experimental method for such tests was also developed. Based on the experimental findings, the mechanics of paper drying was modelled and the stress build-up simulated. Simulation offers a way of studying how the properties of paper develop during drying of wet paper webs.
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Kesler, Olivera E. (Olivera Elizabeth). "Residual stresses and properties of layered and graded coatings." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85368.
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PINTO, JOAO LUIS TEIXEIRA DE MELLO G. "DETERMINATION OF HYDRAULIC PROPERTIES RESIDUAL SOILS IN RIO DE JANEIRO." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2013. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=34829@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
A cidade do Rio de Janeiro apresenta relevo acidentado e clima tropical. Os processos intempéricos que ocorrem na litologia geram os solos residuais e coluvionares. Tendo em vista a limitação espacial de áreas planas, a ocupação antrópica se direciona as áreas de encosta, onde estes solos estão presentes. Ao longo dos anos tem-se estudado que a maioria dos movimentos de massa da cidade do Rio de Janeiro estão relacionados à perda de sucção mátrica do solo. O presente trabalho visa, portanto, a obtenção de parâmetros hidráulicos dos solos não-saturados de maneira simples, rápida e pouco onerosa a fim de viabilizar estudos da infiltração de água em taludes. Para isso, foram estudadas 6 áreas ao longo do Rio de Janeiro, onde a escolha se baseou.na rocha de origem formadora dos solos residuais. Os ensaios do trabalho utilizados foram o Ensaio de Infiltração Monitorada (EIM) e caracterização física, e para efeitos comparativos também foram executados alguns ensaios de Guelph, papel filtro e permeabilidade saturada triaxial. O modelo de interpretação não-saturado usado foi o modelo de van Genutchen-Maulem, e a obtenção de três dos cinco parâmetros foi feita através de uma análise inversa. A curva a ser retroanalisada no ensaio é a série temporal da sucção mátrica.
Rio de Janeiro city is sited on a rugged relief and has a tropical climate. The meteoric processes that take place on its lithology generate the residual and transported soils. Accounting for its limited flat urban space, its habitants tend to live in steep slope areas where such soils are present. For a long time studies have taken place to characterize mass movements and their conclusions relate most of them to the loss of soils matric suction. Therefore the study aims to obtain the unsaturated soil parameters in a simple, rapid and low cost way, which may help future studies of water infiltration on slopes. And thus, 6 locations in Rio de Janeiro were choosen based on the criteria of soil formation, attending different types of gneissic bedrocks. The constitutive model used was the van Genuchten and the method to obtain three of its five parameters was by solving an inverse problem. The curve to be optimized comes from the monitored infiltration test which consists on the record of the matric suction over a constant head infiltration test.
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Babendreier, Justin Eric. "Near aggregation: a time and frequency domain analysis using state trajectories and transfer function residues." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/91080.
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In this thesis we investigate concepts associated with aggregation. The basic idea of aggregation is that there exists a reduced order model such that, for an appropriate initial condition, the trajectories of the reduced-order model are linear combinations of the trajectories of the ful 1-order model. We study systems which do not aggregate exactly, but which "nearly aggregate". It is shown that for "nearly aggregable" systems there exists a reduced-order model such that, for an appropriate initial condition, the trajectories of the reduced-order model are near a linear combination of the trajectories of the full-order model.
Under certain conditions it has also been shown that near-aggregation is equivalent to near-unobservability (roughly, an invariant subspace close to the null space of C). Here we establish a relationship between near-unobservability and modal measures of observability as suggested by Selective Modal Analysis. With this result we then obtain an upper bound on the norm of the transfer function residue using near-unobservability measures. The Generalized Hessenberg Representation (GHR) and Dual GHR are examined throughout this analysis. It is finally shown that for SISO systems, the residue norm may be expressed in terms of certain parameters of the Dual GHR.M.S.
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Gardner, Peter T. "Physical properties affecting the bioconversion of maize stems and other fibre-rich crop residues." Thesis, University of Aberdeen, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338332.
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The aim of this work was to develop methods of measuring pore size and the related surface area and pore volume, and then to apply these methods in studying the effects of degradation and lignification on these properties. Colloidal gold particles of prescribed sizes (2-10 nm in diameter) were used as molecular probes to determine pore size in maize and rape walls of different cell types. The particles were visualised by electron microscopy, and this indicated that the pore size in maize parenchyma walls was somewhere between 3 and 5 nm. Gas adsorption analysis provides information on pore size, surface area and pore volume, and was used to study cell walls of maize, alfalfa, wheat, timothy, and rape. This showed that the overall porous structure of the plants selected was very similar. The pore size distributions showed that the vast majority of pores had radii less than 3 nm, although wheat and timothy appeared to have a greater number of larger pores. The physical properties of plants containing type 1 walls were also investigated by this method. This illustrated how gas adsorption could be used to detect the changes in porosity and surface area which arise from the extraction of pectic polysaccharides. The effect of degradation on porosity was investigated using the same five plant types as had been studied previously. It was found that there was no great change in the porous structure as the walls were digested, except for wheat and timothy which both lost the larger pores they possessed before degradation. This resulted in pore size distributions more typical of the other three plant types. The data indicated that degradation occurred by a surface erosion process. Porosity and surface area did not alter greatly between cell walls of varying levels of lignification.
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Pizzochero, Alessandro. "Residual actuation and stiffness properties of piezoelectric composites : theory and experiment." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50323.
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Plunkett, Richard. "Assessment of residual composite properties as influenced by thermal mechanical aging." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-11072008-063142/.
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Kammouna, Zainab. "Effect of creep strains on the residual mechanical properties of concrete." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI038/document.
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L'objectif de cette thèse est d’étudier l'influence du fluage sur les propriétés mécaniques résiduelle du béton. En effet, les sections des éléments d’une structure précontrainte sont majoritairement soumise à une contrainte de compression. En raison de la relaxation des contraintes (due au fluage du béton notamment) et de la charge appliquée, des contraintes de traction peuvent apparaitre au cours de la vie de l’ouvrage. Ainsi, il est nécessaire de connaître la valeur des propriétés mécaniques résiduelles après l'effet de fluage.Le travail se concentre sur le fluage propre (sans échange hydrique avec le milieu environnant) et il comprend une partie expérimentale et une partie numérique. Dans la partie expérimentale, des essais de fluage en compression et en traction indirect (essai Brésilien) ont été effectués sur le béton en utilisant différents niveaux de chargement appliqué à différents âges du béton. A la fin de chaque essai de fluage, un essai quasi statique a été réalisé sur le même béton pour déterminer l'effet du fluage sur les propriétés mécaniques résiduelles. Afin de vérifier l'effet d’une précharge en compression sur la résistance en traction, comme dans le cas d’une structure précontrainte vieillissante ou soumise à un chargement accidentelle, une campagne d’essai Bresilien avec un préchargement quasi statique en compression a également été réalisée. Les résultats montrent que le comportement après fluage dépend fortement de l’âge de chargement et du sens de sollicitation. Numériquement, un modèle mésoscopiques a été utilisé pour simuler le fluage et les propriétés mécaniques après fluage. En effet, sous un chargement constant seule la pâte de ciment flue tandis que les agrégats agissent comme un obstacle à ce fluage. Par conséquent, les contraintes de traction se produisent à l'interface pâte de ciment/agrégats conduisant à microfissures dans cette zone Les déformations viscoélastique sont correctement reproduite à différents niveaux de chargement mais la modification du comportement résiduel du béton ne peut pas être uniquement expliqué par la micro-fissurationThe aim of this study is to evaluate the effect of creep on the concrete mechanical properties evolution. In prestress structures, in the first concrete is completely subjected to compressive stresses. With time, due to relaxation of the prestressed cables and applied load, some tensile stresses may take place in the concrete. So, it is necessary to know the value of the residual mechanical properties after creep effect.The work which concerns only with basic creep (where there is no drying), includes an experimental part and a numerical part. In the experimental part, compressive and tensile (Brazilian) creep tests were carried out on the concrete using different loading levels that applied at different ages of concrete.At the end of each creep test a strength test was carried out on the same concrete for determining the creep effect on the residual mechanical properties. To evaluate the effect of quasi-instantaneous loading in compression and then in tension, some preloading compressive tests were carried out. These tests were accomplished especially to distinguish the effect of quasi-instantaneous effect from that of creep. A quasi-instantaneous compressive test was achieved until a given level and then a Brazilian strength test was carried out to evaluate the effect of compressive preloading on the tensile strength.Numerically, a mesoscopic model was developed for simulating creep and mechanical properties after creep had taken place. The reason for which this mesoscopic technique was used is related to the fact that under the considered loading level of concrete, only the cement paste creeps while the aggregate act as an obstacle to this creep. As a result, tensile stresses arise at cement past-aggregate interface leading to micro cracks at this zone. With this technique, creep strain can generate some damage at mesoscale without any coupling between creep and damage as in sence phenomenological models
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García, López Natxo. "Biomass utilization for energy purposes in Kenya : Fuel characteristics and thermochemical properties." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-125987.
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Around forty percent of the world´s population, mostly inhabitants of countries with developing economies, rely on the traditional usage of biomass for energy purposes. The major negative consequences are environmental and health effects. Additionally, the most remarkable social consequence is rural poverty which is directly linked to lack of access to electricity. This places the questions related to biomass utilization for energy production at the core of global welfare. The present work was performed as a part of a larger research project funded by Formas and which involves Swedish and Kenyan partners. The aim of this study was to gather basic knowledge about the characteristics of relevant biomass from sub-Saharan Africa, more specifically from Kenya. Eight different types of biomass, including agroforestry trees, agricultural residues, and water hyacinth, were evaluated according to fuel characteristics and thermochemical properties. Ultimate and proximate analyses of the collected biomass were carried out, in addition to heating values analyses. Moreover, the biomass was pelletized and a thermogravimetric analysis was performed in a single pellet reactor. Finally, the composition of the residual ashes was determined. The results show that there was a large variation in the fuel characteristics and thermochemical behaviour of the studied agricultural residues and water hyacinth biomass types, whereas agroforestry trees had rather similar properties and thermochemical behaviour when combusted at the same temperature. In addition, results from the ash composition analyses showed large differences among the studied biomass types, which can be used to better predict and solve problems related to the combustion of these biomass types.
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Herron, Lissa. "Determining Which Tryptophan Residues Give Rise to Fluorescence Properties in the Metallo-Beta-Lactamase L1." Miami University Honors Theses / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=muhonors1110916836.
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Colman, Charlotte. "Gypsum residues in fine recycled aggregates : effects on mechanical and microstructural properties of cementitious composites." Electronic Thesis or Diss., Ecole nationale supérieure Mines-Télécom Lille Douai, 2020. http://www.theses.fr/2020MTLD0012.
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Les sables recyclés représentent un flux important de déchets provenant de la démolition d’anciennes structures en béton. Ils ne sont jusqu’à présent pas valorisés à cause d’une absorption d’eau élevée, d’une densité plus faible et d’une teneur en fines plus importante que dans les granulats naturels. De plus, ils sont souvent contaminés par des sulfates. Ces sulfates pourraient provenir du plâtre du bâtiment démoli ou du ciment résiduel qui est couramment présent dans ces matériaux. Le taux de sulfate recommandé pour les granulats recyclés est inférieur à 0,2 % en masse selon la norme EN206, afin de limiter le risque d’attaque sulfatique : la réaction entre les composants du ciment, l’eau et les sulfates entraîne la formation de minéraux expansifs comme l’ettringite. Cette expansion peut éventuellement conduire à une fissuration du matériau et à une perte générale des performances mécaniques. Une étude systématique a permis de mettre en évidence que les sables recyclés provenant des centres de recyclage contenaient de 0,15 à 0,80 % de sulfates ce qui est plus ce qui est autorisé. Néanmoins, ces quantités n’ont pas engendré de gonflement ni de dégradation lorsque les granulats contaminés ont été incorporés dans des mortiers. Une teneur en sulfate très élevée de 3 % a été nécessaire pour observer une expansion significative ; toutefois l’expansion a pu être contrôlée en augmentant l’alcalinité d’un mélange. Des bétons fabriqués avec différents niveaux de sulfates ont présenté des gonflements ou non : l’ampleur d’expansion n’était pas proportionnelle à la teneur en sulfate. Le seuil qui a déclenché la réaction de gonflement dépendait aussi du type de granulat. Les résultats de cette étude fournissent des recommandations pour l’utilisation de sables recyclés contaminés par des résidus de gypse : une teneur en sulfate jusqu’à 0,3 % pourrait être possible, et même plus en fonction de certains paramètres et compositions de mélange. La limite actuelle est de 0,2 % semble trop stricte et freine la valorisation de sables recyclés dans des bétons durables et résistantsFine recycled aggregates are an important waste steam coming from the demolition of old concrete structures. They are up to now not valorized because of an increased water absorption, lower density and higher fines content compared to natural aggregates. Moreover, they often have a high sulfate concentration. These sulfates could have originated from plaster in a demolished building, or from the residual cement that is commonly present in these materials. The sulfate level of recycled aggregates is recommanded to stay under 0.2 mass% by standard EN206, to limit the risk on sulftate attack: the reaction between cement components, water and sulfates results in the formation of expansive minerals such as ettringite. This expansion can eventually lead to cracking of the material and a general loss in mechanical performances. Fine recycled aggregates from recycling plants did contain 0.15 to 0.80 % of sulfates which is more than allowed, but these amounts did not cause any swelling or degradation when the aggregates were incorporated into mortars. A very elevated sulfate content of 3 % was needed to observe significant expansion, and even this level of contamination could be mitigated by increasing the alkalinity of a mix. Concretes made with varying sulfate levels either expanded or they didn’t: the absolute swelling amount was not proportional to its sulfate content. The actual threshold concentration that started the swelling reaction was dependant on the type of coarse aggregate. The results of this study provide recommandations for the use of fine recycled aggregates contaminated with gypsum residues : a sulfate content of at least 0.3 % could be possible, and even more if certain parameters and mix compositions can be adjusted accordingly. The current limit of 0.2 % seems too strict and hinders the valorization of fine recycled aggregates in high quality construction applications
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Tanimizu, Naoki. "Conformational properties of amino acid residues in the active site of bovine pancreatic ribonuclease A." Kyoto University, 1999. http://hdl.handle.net/2433/181366.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第7960号
農博第1069号
新制||農||785(附属図書館)
学位論文||H11||N3294(農学部図書室)
UT51-99-M265
京都大学大学院農学研究科農芸化学専攻
(主査)教授 林 力丸, 教授 池田 篤治, 教授 岩村 俶
学位規則第4条第1項該当
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John, H. D. "The interaction between residual stresses, processing and mechanical properties in acrylic polymers." Thesis, Swansea University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637434.
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The overall aim of this work was to relate the molecular structure of injection-moulded PMMA with the levels of residual stress and processing conditions with levels of residual stress for extruded sheet. Experimental work was conducted on an experimental copolymer, supplied by ICI Plc, containing both methyl methacrylate and ethyl acrylate. Injection-moulded samples were manufactured varying in terms of molecular weight and percentage of ethyl acrylate. The influence of roll temperature and line speed during extrusion on levels of residual stresses and orientation were also studied in samples extracted from both the longitudinal and transverse directions of the extruded sheet. Residual stress distributions were calculated using the layer removal technique, birefringence measurements and in extruded samples, initial curvature measurements. Shrinkage measurements were also taken to identify the relative degree of orientation in the materials. Properties such as tensile and flexural modulus, together with tensile strength were measured. Overall, injection mouldings exhibited a parabolic residual stress distribution, with compressive stresses on the surface and tensile stresses in the core. Increasing molecular weight and decreasing levels of ethyl acrylate led to greater residual stresses being present in the material. Extruded material, however, contained tensile stresses on the surface and a less symmetrical distribution overall. The magnitudes of residual stress were lower than found in injection mouldings and lower in the transverse direction of the extruded sheet. Overall, lower roll temperatures and faster line speeds led to increased residual stresses, shown by initial curvature, layer removal and birefringence measurements. However, higher roll temperatures and slower line speeds led to increased orientation in the sheet as shown by shrinkage measurements. Thus, processing conditions during extrusion had opposite effects on residual stresses and orientation.
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Wilkinson, Simon B. "Residual stress and through depth modulus properties of short fibre reinforced composites." Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308979.
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Ellison, Sara Fisher. "A nonparametric residual-based specification test : asymptotic, finite-sample, and computational properties." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12697.
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Westin, Johan. "Ballistic Impact Properties of Fibre-Reinforced Composite Structures." Thesis, KTH, Farkost och flyg, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-39676.
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梁偉賢 and Wai-yin David Leung. "Synthesis and physical properties of fatty acid derivatives containingamino, amido functions and L-amino acid residues." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31233752.
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DEMUELENAERE, RAFAEL GERARD DE ALMEIDA. "CHARACTERIZATION OF HEAVY METAL TRANSPORT PROPERTIES IN RESIDUAL SOILS IN RIO DE JANEIRO." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5462@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOPROGRAMA DE APOIO A NÚCLEOS DE EXCELÊNCIA
A contaminação do meio ambiente de subsuperfície com resíduos perigosos e tóxicos tem se tornado um dos maiores problemas ambientais em vários países, com muitos locais apresentando contaminação da água subterrânea. A dissertação visa a caracterização de propriedades de transporte em solos residuais do estado do Rio de Janeiro; em especial será focalizado o comportamento e a mobilidade neste solo de metais pesados como o cádmio, zinco, cromo e chumbo. O conhecimento do comportamento dos metais no solo é importante para a previsão de acidentes ambientais e para a avaliação de possíveis soluções. Mudanças no ambiente, como variação do pH, podem interferir no comportamento do metal, desta forma o conhecimento das condições locais é importante para previsão do comportamento do contaminante. Foram realizados ensaios de batelada e de coluna com diferentes metais, para entender como se comportam nos solos residuais caracterizados. Para complementar o estudo uma modelagem geoquímica foi feita a partir dos dados experimentais com o programa computacional PHREEQC.
The contamination of the underground environment by hazardous and toxic wastes has become one of the main environment problems in several countries where many sites present groundwater infection. The project purpose is the characterization of the transport properties in residual soils of the Rio de Janeiro state. Mainly it will be focused the behaviour and the mobility of heavy metals, for example, the cadmium, the zinc, the chromium and the lead in this kind of soil. To know the behaviour of the metals in the soil is important for the prevision of environmental accidents and for the evaluation of possible solutions. Changes in the environment, as the pH variation, may interfere in the metal conduct thus the knowledge of the local conditions is essential for the prevision of the contamination procedure. Batch and column tests were made using different metals in order to understand how they act in the characterized residual soils. To complement the studies a geochemical modeling was made using the experimental data with the compute program, PHREEQC.
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Fu, Yu. "Residual Strength of Metal Particulate Reinforced Ceramic Matrix Composites with Multiple Cracks." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/FuY2008.pdf.
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Hurlston, Robert George. "Development of advanced methods for quantifying fracture toughness properties in the presence of residual stresses." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/development-of-advanced-methods-for-quantifying-fracture-toughness-properties-in-the-presence-of-residual-stresses(d5b6ce24-2135-4139-99f2-97377e43c712).html.
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Welding is an essential process in many industries for both the production and repair of engineering plant, notably pressure vessels and piping. However, welding processes cause large magnitudes of residual stress to be induced within the structure. Residual stress can be defined as a stress that exists in a material when it is under no primary loading. Whilst residual stresses can be reduced by post weld heat treatment, such treatments are not always possible, and so high residual stresses can remain in serviceThe current methodology for evaluating fracture toughness from specimens, particularly if these contain weld residual stresses is presented in BS7448-1997. This method relies on the assumption that the effect of residual stress on fracture toughness measurements can be negated by the application of a local compression, to the ligament ahead of the pre-crack in the test specimen. Recent research has investigated the validity of this assumption. The results suggest that, far from being removed, the residual stresses are modified or even enhanced via local compression. This can reduce the value of measured fracture toughness below its true value. In order to ensure the validity of fracture toughness measurements in materials that contain residual stress, a more robust method for its quantification is developed.The aim of this project was to extend current understanding regarding the magnitude and distribution of residual stresses retained in standard fracture mechanics specimens removed from welds and the consequent effects of these stresses on measured fracture toughness, both in terms of the crack driving force and crack-tip constraint. Furthermore, the project aimed to derive improved methods for the quantification of valid values of fracture toughness from laboratory specimens containing residual stresses. This was achieved via a combination of analytical and experimental work.The effect of specimen extraction on the level of retained residual stress in specimens extracted from non stress-relieved welds was investigated using parametric finite element analyses. Simplified methods to quantify the levels of residual stresses in fracture mechanics specimens removed from welds and their significance, in terms of contribution to crack driving force, are proposed.The influence of residual stresses on the measured fracture toughness properties of ferritic pressure vessel steel, tested in the cleavage fracture regime, has also been studied. A refined method of out-of-plane compression was devised and used to generate significant residual stresses in three-point bend specimens. This method was then used experimentally, alongside supporting elastic-plastic analyses, to quantify the effects of the residual stresses on fracture toughness in terms of both crack driving force and crack-tip constraint in geometrically high and low constraint specimens. A method whereby fracture toughness data, obtained from specimens containing residual stresses, can be corrected to provide valid fracture toughness properties using constraint based fracture mechanics alongside a simple fracture model has been proposed. The main conclusions from the work are as follows. Significant weld residual stresses have been shown to be retained in certain laboratory specimens post extraction from non stress-relieved welds. The magnitude and distribution of retained residual stress has been shown to be dependant on: • Material yield and flow properties • Specimen size; where larger specimens are more likely to retain significant levels of residual stress than smaller specimens • Specimen type; either compact tension (CT) or single edge notched bend (SENB), where there is a tendency for specimens to retain higher relative levels of residual stress in the directions of their largest dimensions; i.e. bend specimens retain more residual stress along their length than CT specimens and CT specimens retain more residual stress across their width than bend specimens • Extraction location, e.g. full thickness, near surface, mid-thickness etc. The stress partitioning method has been shown to provide a useful estimating approach for assessing the levels of residual stress retained in fracture mechanics specimens extracted from non stress-relieved welds in certain orientations.Retained residual stresses have been shown to affect both crack driving force and crack-tip constraint in both low and high geometrically constrained 50mm bend specimens manufactured from A533B ferritic steel. The residual stress has been shown to dominate the level of crack-tip constraint condition over and above the geometric and loading factors during the early stages of loading. The effects of residual stress on crack driving force and crack-tip constraint have been shown to result in fracture loads and, therefore, measured fracture toughness values that vary widely from those to be expected in the material under small-scale yielding conditions; i.e. if a standard specimen were to be tested containing no residual stress. Two-parameter (J-Q) fracture mechanics has been shown to provide a valid approach for quantifying fracture toughness properties from high and low constraint specimens, with and without residual stresses, with all data being shown to be consistent with a J-Q failure locus for a given level of cleavage probability.
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Leung, Wai-yin David. "Synthesis and physical properties of fatty acid derivatives containing amino, amido functions and L-amino acid residues /." [Hong Kong : University of Hong Kong], 1993. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13637666.
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Urriolagoitia, Sosa Guillermo. "Analysis of prior strain history effect on mechanical properties and residual stresses in beams." Thesis, Oxford Brookes University, 2005. https://radar.brookes.ac.uk/radar/items/bf0647c5-7163-47c6-940c-c24aa7ab618f/1.
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The crack compliance method (eeM) has attracted a lot of interest as an inexpensive method for the determination of residual stresses in materials compared to the use of Xray and neutron diffraction methods. The vast majority of the work found for the application of the eeM in the literature concentrated on the determination of residual stresses in annealed beam specimens. There is very little evidence of the verification of the method in cases where the material might have experienced prior strain loading effect such as Bauschinger effect before the residual stress is induced. This thesis has applied the eeM for the determination of residual stresses in bemus that were under Bauschinger effect before the residual stress was induced. The thesis also briefly considers the application of the eeM for the study of cyclic loading effect on the relaxation of residual stresses in beams. In order to achieve the aims highlighted above, the thesis develops a new efficient solution for the simultaneous determination of tensile and compressive stress-strain behaviour in materials under Bauschinger effect. The determination of these properties helps with the verification of the results of the eeM by using another relatively simple and inexpensive method based on the superposition of loading and unloading stresses. A new simple support method for beams subjected to electro-discharge machining (EDM) is also introduced. The new cutting arrangement allows free deformation of beams during cutting and allows the plane of cutting to be maintained without deviation. The experimental testing and verification procedure considers several factors such as different materials, heat treatment conditions, various levels of pre-straining and different fatigue load amplitudes. Several aspects of the crack compliance method are verified. The results obtained in all cases are generally very encouraging.
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Salih, Anmar Mahdi. "Characterization of In-Vivo Damage in Implantable Cardiac Devices and the Lead Residual Properties." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1557851495921852.
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Lordelo, Rodrigo Seixas Dourado. "Avalia??o da utiliza??o de residuo de vidro de garrafas na produ??o de argamassa." Universidade Estadual de Feira de Santana, 2018. http://tede2.uefs.br:8080/handle/tede/700.
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The use of waste incorporated in building materials has been pointed out as an alternative for more adequate disposal of solid waste. Among the wastes generated in Brazil, are the glass. Less than half of the glass bottles produced in Brazil are recycled. In the present work the influence of the use of waste glass of brown bottles, crushed, as partial substitute of the natural sand, in the production of mortars was evaluated. The substitution contents evaluated were 10, 20 and 30%, by mass, in addition to the reference mortar (without waste glass). The properties of the mortars in the fresh state were evaluated (workability, specific mass and incorporated air content) and also in the hardened state (flexural tensile strength, compressive strength, water absorption, void index, specific mass and alkali-silica reactivity). The results of the tests indicated that the use of waste glass bottles, replacing the natural aggregate, did not alter the fluidity of the mortars, but decreased the density and increased the content of incorporated air. The incorporation of the waste provided an increase in the tensile strengths in flexion and compression, in relation to the reference mortar. With respect to the possible alkali-silica reactivity, it was verified that the mortars with the waste glass bottle did not exceed the expansion limit established in accordance with NBR 15577-4 (ABNT, 2009). Based on the results it was concluded that it is possible to use up to 30% of waste glass of brown bottles, replacing the natural sand.
A utiliza??o de res?duos incorporados ? materiais de constru??o vem sendo apontada como uma alternativa para destina??o mais adequada dos res?duos s?lidos. Dentre os res?duos gerados no Brasil, est?o os de vidro. Menos da metade das embalagens de vidro produzidas no Brasil s?o recicladas. No presente trabalho foi avaliado a influ?ncia da utiliza??o de res?duo de vidro de garrafas de cor marrom, triturado, como substituto parcial do agregado mi?do natural, na produ??o de argamassas. Os teores de substitui??o avaliados foram de 10, 20 e 30%, em massa, al?m da argamassa de refer?ncia (sem res?duo). Foram analisadas propriedades das argamassas no estado fresco (trabalhabilidade, massa espec?fica e teor de ar incorporado) e no estado endurecido (resist?ncia ? tra??o na flex?o, resist?ncia ? compress?o, absor??o de ?gua, ?ndice de vazios, massa espec?fica e reatividade ?lcali-s?lica). Os resultados dos ensaios indicaram que o uso de res?duo de vidro de garrafa, em substitui??o ao agregado natural, n?o alterou a fluidez das argamassas, mas diminuiu a densidade e aumentou o teor de ar incorporado. A incorpora??o do res?duo proporcionou aumento nas resist?ncias ? tra??o na flex?o e ? compress?o, comparado ? argamassa de refer?ncia. Com rela??o ? poss?vel reatividade ?lcali-s?lica, verificou-se que as argamassas com o res?duo de vidro de garrafa n?o excederam o limite de expans?o estabelecido conforme a NBR 15577-4 (ABNT, 2009). Com base nos resultados concluiu-se que ? poss?vel utilizar at? 30% de res?duo de garrafa de vidro de cor marrom, em substitui??o ao agregado natural.
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Marciszko, Marianna. "Diffraction study of mechanical properties and residual stresses resulting from surface processing of polycrystalline materials." Thesis, Paris, ENSAM, 2013. http://www.theses.fr/2013ENAM0037/document.
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Méthodologie de mesures de contraintes avec la méthode multireflection pâturage d'incidence(MGIXD) a été étudié et développé. La géométrie du faisceau parallèle a été appliquée pour mensurationsde stress. Le faisceau incident dans diffractomètres classiques a été collimaté par le miroir Göbel et lesessais de configuration en parallèle ont été effectuées pour Al poudre. Les résultats confirmé que le erreurstatistique et l'erreur d'alignement peuvent être réduits lorsque le miroir Göbel est utilisé. Facteursphysiques ont été prises en compte dans la CSX (analyse aux rayons X du stress): Lorentz - polarisationet facteur d'absorption (LPA) et aussi correction de la réfraction (RC). Les résultats montrent quel'influence de LPA est mineur dans CSX, mais la RC peut influencer de manière significative l'analyse.Dans la thèse de la question de RC a été examiné et comparé avec les approches présentées dans lalittérature. Dans la thèse de deux développements théoriques de la méthode MGIXD ont été présentés: laprocédure de détermination de paramètre c/a et l'influence des défauts d'empilement sur les résultats. Il aété montré que les deux développements améliore de manière significative la qualité de l'analyse desdonnées expérimentales. Dans le présent travail le problème de la X -ray facteurs de stress (XSF) utiliséspour l'interprétation des résultats CSX a été étudiée. Différents modèles théoriques de grains élastoplastiqueinteraction ont été envisagées et appliquées dans la CSX. Vérification de la XSF durant l'essaide traction pour l'échantillon élastique anisotrope (en acier inoxydable austénitique) et pour l'échantillonisotrope (Ti - note2). Anisotropie de XSF a également été observée dans: rectifié alliage Ni, acierinoxydable austénitique poli et revêtement CrN. Les résultats montre que Reuss et modèle de la surfacelibre sont en meilleur accord avec les résultats expérimentaux. Enfin, la méthode MGIXD a été vérifiée enutilisant le rayonnement synchrotron et 3 longueurs d'onde différentes. La méthodologie a été développéepour traiter les données non seulement pour les différents angles d'incidence, mais aussi en utilisantdifférentes longueurs d'onde simultanément. Contraintes en fonction de «vraie profondeur» a été calculéeen utilisant la transformée de Laplace inverse. Analyse Wiliamson-Hall a été appliquée pour les données.Méthode MGIXD a été appliqué pour les mesures de diffraction de dispersion d'énergie dans lequel lefaisceau blanc a été utilisé: 0,3 à 0,18 Å. L' analyse des contraintes a été effectuée en utilisant troisméthodes différentes : la méthode de sin2ψ norme, la méthode de terrain universelle et en utilisantmultireflection analyse . Dans la gamme de profondeur de pénétration à 0-15 um de la convergence desrésultats obtenus à partir de différentes méthodes a été acquise . En outre, les données de synchrotronparfaitement en accord avec les résultats obtenus en laboratoire sur diffractomètre (rayonnement Cu Ka) àproximité de la surface . Pour profondeur supérieure à 14 um points expérimentaux présentent desvariations importantes et ne sont pas d'accord avec les résultats de la méthode standard.Mots clés : contraintes résiduelles, diffraction des rayons X, méthode de l’incidence rasante, miroir GöbelMethodology of stress measurements with multireflection grazing incidence method (MGIXD)was investigated and developed. The parallel beam geometry was applied. The incident beam in classicaldiffractometers was collimated by Göbel mirror and the tests of parallel configuration were performed for Alpowder. Results confirmed that both statistical error and the misalignment error can be reduced when theGöbel mirror is used. Physical factors were taken into account in XSA (X-ray stress analysis): Lorentzpolarizationand absorption factor (LPA) and also refraction correction (RC). Results showed that theinfluence of LPA correction is minor in XSA but the RC can significantly influence analysis. In the thesisthe issue of RC was considered and compared with approaches presented in the literature. In the thesistwo theoretical developments of the MGIXD method were presented: the procedure of c/a parameterdetermination and the influence of stacking faults on the results was taken into account. It was shown thatboth developments significantly improves the quality of experimental data analysis. In the present work theproblem of X-ray stress factors (XSF) used for the interpretation of XSA results was studied. Differenttheoretical grain elasto-plastic interaction models were considered and applied in XSA. Verification of theXSF was during tensile test for austenitic stainless steel and for the isotropic sample. Anisotropy of XSFwas also observed in: ground Ni alloy, polished austenitic stainless steel and CrN coating. The resultsshows that Reuss and free surface grain interaction models are in the best agreement with theexperimental results. Finally the MGIXD method was verified using synchrotron radiation and 3 differentwavelengths. The methodology was developed to treat data not only for different incident angles but alsousing simultaneously different wavelengths. Stresses vs. z – ‘real depth’ was calculated using the inverseLaplace transform applied to polynomial function. Wiliamson-Hall analysis was applied for collected data.Next multireflection method was applied for the energy dispersion diffraction measurements in which whitebeam containing radiation having different wavelengths was used (λ (Ǻ): 0.3–0.18/ E (keV): 40-68). Thestress analysis was performed using three different methods: standard sin2ψ method, Universal plotmethod and by using multireflection analysis. In the range of penetration depth to 0-15 μm theconvergence of the results obtained from different methods was gained. Moreover the synchrotron dataperfectly agree with the results obtained on laboratory diffractometer (Cu Kα radiation) close to the surface.For depth larger than 14 μm the experimental points exhibit significant spread and do not agree with theresults of standard method
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Stadelmann, Richard. "Mechanical Properties and Thermal Residual Stresses of ZrB2-SiC Ceramic Composites for Hypersonic Vehicle Applications." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6022.
Full textAbstract:
Ultra High Temperature Ceramic (UHTC) ZrB2- 10, 20, 30wt%SiC composites are of high interest for use in hypersonic air-breathing vehicles. In this work, ZrB2- 10, 20, 30wt%SiC UHTC composites were produced by the Spark Plasma Sintering (SPS) technique. After sintering, almost dense ceramics with ~ 5-8% porosity were produced. Their mechanical properties, such as Young's, shear, and bulk moduli, along with Poisson's ratio, 4-point bending strength, and single edge V-notched beam (SEVNB) fracture toughness were measured. In addition, in-situ bending experiments under a Raman microscope were performed to determine the piezo-spectroscopic coefficients of SiC Raman active peaks for calculation of thermal residual stresses. The results show that these materials are possible candidates for hypersonic air-breathing vehicles due to their high Young's modulus, ability to withstand high temperatures, and relatively low densities.M.S.A.E.
Masters
Mechanical and Aerospace Engineering
Engineering and Computer Science
Aerospace Engineering; Thermofluid Aerodynamic Systems