Tesi: "Expansion de soi"

1

Nachit, Oussama. "Mieux comprendre l'EXPansion et l'EXTension de soi du consommateur : une application à un objet connecté". Electronic Thesis or Diss., Université de Montpellier (2022-....), 2024. http://www.theses.fr/2024UMOND008.

Testo completo

Abstract (sommario):

Dans un monde technologiquement avancé où les objets connectés deviennent une partie de notre identité personnelle, cette thèse examine les relations entre les individus et leur montre connectée à travers les prismes de l'EXPansion de soi (Aron et Aron, 1986) et de l'EXTension de soi (Belk, 1988). Cette recherche met en lumière la manière complexe et riche dont les individus intègrent ces dispositifs dans leur conception de soi, modulant ainsi leur attachement et leur intention de poursuivre l'utilisation de ces technologies. Ainsi, la problématique de ce travail doctoral s'articule comme suit : « Quelles sont les relations entretenues par les individus avec leur montre connectée via l'EXPansion et l'EXTension de soi, et l'impact de ces dernières sur l'attachement et la continuité d'utilisation de ces montres ? » Cette question a conduit à une enquête structurée autour de quatre questions de recherche spécifiques qui cherchent à explorer les manifestations de ces processus psychologiques dans le cadre des interactions avec une montre connectée. Cette recherche adopte une approche mixte, combinant des analyses qualitatives pour détailler les expériences des utilisateurs avec leurs montres connectées, suivies de deux études quantitatives pour mesurer l'impact des motivations d'achat et des attributs de la montre sur l'EXPansion et l'EXTension de soi. Les méthodes employées ont permis de valider les relations hypothétiques entre les construits théoriques et les comportements des utilisateurs. Les résultats révèlent que les montres connectées sont perçues non seulement comme des outils fonctionnels mais aussi comme des éléments essentiels de l'identité des utilisateurs. Les résultats montrent que les motivations d'achat agentiques et les attributs de la montre impactent directement l'EXPansion de soi, qui à son tour facilite l'EXTension de soi, menant à un plus grand attachement et une intention renforcée de continuer à utiliser la montre. Ces résultats soulignent la séquentialité des processus d'EXPansion et d'EXTension de soi dans la formation de l'attachement aux objets connectés. Les implications de cette recherche sont significatives pour les fabricants de montres connectées, et les apports théoriques multiples s'inscrivent dans la littérature portant sur l'EXPansion et L'EXTension de soi. La thèse reconnaît les limites liées à la focalisation sur les montres connectées et suggère d'élargir l'analyse à d'autres technologies portables pour examiner si les découvertes se généralisent à d'autres dispositifs
In a technologically advanced world where connected objects become a part of our personal identity, this thesis examines the relationships between individuals and their smartwatches through the prisms of self-EXPansion (Aron and Aron, 1986) and self-EXTension (Belk, 1988). This research highlights the complex and rich manner in which individuals integrate these devices into their self-concept, thus modulating their attachment and intention to continue using these technologies. Therefore, the central problem of this doctoral work is articulated as follows: "What are the relationships maintained by individuals with their smartwatch via self-EXPansion and self-EXTension, and the impact of these processes on the attachment and continued use of these watches?" This question led to a structured investigation around four specific research questions that seek to explore the manifestations of these psychological processes in the context of interactions with a smartwatch.This research adopts a mixed-methods approach, combining qualitative analyses to detail the experiences of users with their smartwatches, followed by two quantitative studies to measure the impact of purchase motivations and watch attributes on self-EXPansion and self-EXTension. The methods used validated the hypothetical relationships between the theoretical constructs and user behaviors. The findings reveal that smartwatches are perceived not only as functional tools but also as essential elements of the users' identity. The results show that agentic purchase motivations and the attributes of the watch directly impact self-EXPansion, which in turn facilitates self-EXTension, leading to greater attachment and a reinforced intention to continue using the watch. These results underscore the sequentiality of the self-EXPansion and self-EXTension processes in the formation of attachment to connected objects.The implications of this research are significant for manufacturers of smartwatches, and the multiple theoretical contributions fit into the literature on self-EXPansion and self-EXTension.The thesis acknowledges the limitations related to the focus on smartwatches and suggests broadening the analysis to other wearable technologies to examine whether the findings generalize to other devices

Gli stili APA, Harvard, Vancouver, ISO e altri

2

Castro, Gonzales Milagros Alessandra, e Pereyra Jesus David Navarro. "Análisis de mejora de suelos arcillosos de alta plasticidad a nivel de subrasante mediante adición de cemento Portland para disminuir el cambio volumétrico". Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2019. http://hdl.handle.net/10757/626119.

Testo completo

Abstract (sommario):

Esta investigación comprende el potencial de resistencia y la expansión que presenta el suelo, dicha evaluación es realizada mediante ensayos CBR. Se utiliza la técnica de suelo cemento para mejorar las características físicas y mecánicas, este proceso consiste en mezclar al material con cemento Portland Tipo I formando suelo cemento 10%, 15% y 20%, los cuales presentan un incremento del CBR (máximo: 138.7% y mínimo: 91.9%) logrando un tipo de subrasante extraordinaria para resistir la estructura del pavimento y una reducción de 7.18% en la expansión de las muestras.
This research includes the potential for resistance and the expansion that the soil presents, this evaluation is carried out through CBR tests. The soil cement technique is used to improve the physical and mechanical characteristics, this process consists in mixing the material with Portland cement type I. That combination forms soil cement 10%, 15% y 20%, which present an increase of the CBR (max: 138.7% y min: 91.9%) achieving a type of extraordinary subgrade to resist the structure of the pavement and a reduction of 7.18% in the expansion of the samples.
Tesis

Gli stili APA, Harvard, Vancouver, ISO e altri

3

Russell, Adrian Robert Civil &amp Environmental Engineering Faculty of Engineering UNSW. "Cavity expansion in unsaturated soils". Awarded by:University of New South Wales. School of Civil and Environmental Engineering, 2004. http://handle.unsw.edu.au/1959.4/22263.

Testo completo

Abstract (sommario):

The problem of cavity expansion in unsaturated soils is investigated. A unified constitutive model for unsaturated soils is presented in a critical state framework using the concepts of effective stress and bounding surface plasticity theory. Consideration is given to the effects of suction and particle crushing in the definition of the critical state. A simple isotropic elastic rule is adopted. A loading surface and bounding surface of the same shape are defined using simple and versatile functions. A limiting isotropic compression line exists, towards which the stress trajectories of all isotropic compression load paths approach. A non-associated flow rule is assumed for all soil types. Isotropic hardening/softening occurs due to changes in plastic volumetric strains as well as suction for some unsaturated soils, enabling account of the phenomenon of volumetric collapse upon wetting. Results of isotropic compression tests, oedometric compression tests and drained and undrained triaxial compression tests performed on Kurnell (quartz) sand in saturated and unsaturated states and subjected to stresses sufficient to cause particle crushing are presented and used to calibrate the model. The model is also calibrated using results reported in the literature for triaxial tests performed on saturated and unsaturated speswhite kaolin and three load paths. For both soils the model leads to a much improved fit between simulation and experiment compared to that for models based on conventional plasticity theory. The model is implemented into a cavity expansion analysis using the similarity technique, extended for application to unsaturated soils. Cylindrical and spherical cavities are considered, as are drained and undrained conditions. Cavity expansion results for the bounding surface model and conventional plasticity models are compared for saturated conditions. Substantial differences highlight the importance of adopting a model that accurately describes stress-strain behaviour. Cavity expansion results for the bounding surface model and saturated and unsaturated conditions are also compared. Substantial differences, particularly in the limit pressure, highlight the major influence of suction and the importance of accounting for this when using cavity expansion theory to interpret results of the cone penetration and pressuremeter tests.

Gli stili APA, Harvard, Vancouver, ISO e altri

4

Evans, Michael, Richard W. Stoffle e Elizabeth Krause. "Santa Fe Ski Basin Proposed Expansion Ethnographic Assessment". Bureau of Applied Research in Anthropology University of Arizona, 1993. http://hdl.handle.net/10150/271443.

Testo completo

Abstract (sommario):

The purpose of this research study was to conduct an ethnographic assessment for an Environmental Impact Statement (EIS) of a proposed expansion plan for the Santa Fe Ski Area located in the Sangre de Cristo Mountains north of Santa Fe, New Mexico. Along with expansion into forest areas outside the existing Special Use permit boundaries, the proposed plan includes new buildings, parking lots, lifts, ski runs, and snowmaking within the existing ski area boundary. The ethnographic assessment concentrates on those cultural resources known to be in the area, as identified by Pueblo participants in the research study. This project had three objectives: a) what impact would the project have on the traditional uses, cultural uses, values, and belief practices of Tesuque Pueblo and other Pueblos' uses of the area; b) how would the ski area expansion affect the traditional use area of the Tesuque Pueblo and other Pueblos; and c) what specific areas of traditional cultural use, including those of Hispanic origin, would be affected by the proposed alternatives.

Gli stili APA, Harvard, Vancouver, ISO e altri

5

Simões, Francisco Xavier Paranhos Coêlho. "Avaliação da regeneração óssea, sob a influência do laser de baixa intensidade, na região da sutura palatina de ratos após expansão da maxila". Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/23/23132/tde-08042009-152050/.

Testo completo

Abstract (sommario):

Uma das condutas terapêuticas mais adotadas na prática ortodôntica para a correção da mordida cruzada posterior é a expansão rápida da maxila. A recidiva pós-disjunção demonstra a necessidade do uso de contenção para garantir o sucesso da terapia. A sutura neoformada e as maxilas devem se manter em sua nova posição por um período mínimo para adquirir estabilidade. Seria um benefício acelerar a neoformação óssea na sutura palatina após a expansão com o objetivo de reduzir o tempo do período de contenção. O uso do laser na regeneração óssea é justificada pela possibilidade de diminuir o tempo de contenção garantindo assim maior estabilidade pós-tratamento. O presente estudo teve como objetivo verificar o efeito do laser de baixa intensidade com diferentes potências na regeneração óssea na região da sutura palatina. Foram utilizados 20 ratos (Wistar), com 45 (quarenta e cinco) dias de idade, divididos em 5 (cinco) grupos, sendo 4 (quatro) ratos cada um, assim descritos: Grupo 1 Não irradiados nem submetidos a disjunção e Grupo 2 Não irradiados, mas submetidos a disjunção. Os Grupos experimentais serão assim distribuídos: Grupo 3 submetidos a disjunção e irradiados com dose única de 4J/cm2; Grupo 4 submetidos a disjunção e irradiados com dose única de 8 J/cm2 e Grupo 5 - submetidos a disjunção e a irradiação com 2 doses de 4 J/cm2. Os grupos irradiados receberam as doses no momento 0 (zero início do estudo) e dois dias após a primeira dose, quando indicado. A aplicação foi feita na sutura palatina mediana. Os ratos sofreram eutanásia, nos seguintes tempos: 10, 30, 70 e 150 dia e procedem-se a avaliação histológica dos tecidos. Para a análise dos resultados foi utilizado o teste Exato de Fisher. No grupo 1, observamos desenvolvimento normal do osso na região da sutura palatina mediana. No Grupo 2, observamos área de neo-formação óssea, com a presença de vários osteoblastos. Os grupos submetidos a disjunção e laserterapia (Grupos 3, 4 e 5) apresentaram comportamento similar entre si, mas com algumas particularidades. Com os resultados obtidos neste trabalho pode-se concluir que a laserterapia tem discreto efeito na remodelação óssea da sutura palatina em ratos e os grupos experimentais apresentaram menor grau de inflamação da região estudada, mas não foi estatisticamente significante.
Rapid maxillary expansion is one of the therapy used in the practice orthodontic to the posterior crossbite correction. Relapsed after expansion treatment required a contention device to guarantee a success therapy. The neoformation suture and the maxilla have maintained in the new position for a period to get the stability. To accelerate the osseous regeneration in the medline suture after expansion to reduce the retention period. The use of laser in the osseous regeneration its possible to decreased the retention period to guarantee the stability after treatment. The aim of the study was to investigate the low power laser efect with different power in the osseous regeneration in the midline palatal suture. Twenty male rats (Wistar) 45 days old were used. The animals were divided into five groups: group 1 Non irradiation and non expansion; group 2 Non irradiation and expansion; group 3 expansion and one dose of irradiation 4J/cm2; group 4 expansion and one dose of irradiation 8 J/cm2;: and group 5 - expansion and two dose of irradiation 4 J/cm2. The irradiation groups were irradiated in the first day and the group 5, the second irradiation was two days after the first time. The irradiation was done in the palatal suture. The animals received intraperitoneally injection in the: 10, 30, 70 and 150 day and were evaluated histologically. The results was analysis by the Fisher test. Group 1 showed a osseous normal development in the midline palatal suture. Group 2 showed a osseous regeneration with oesteoblasts. The expansion and lasertherapy group (group 3, 4 e 5) showed similar results. The conclusions drawn from this study are that the laser therapy has a light effect in the osseous regeneration in the midline palatal suture in rats and the experimental group showed less inflammation in the suture area but not statistically significance.

Gli stili APA, Harvard, Vancouver, ISO e altri

6

Sapkota, Binod Kumar. "Soil/pavement interaction for pavements on expansive soil". Thesis, Queensland University of Technology, 1994.

Cerca il testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

7

Ehrenstråhle, Carl. "Polynomial Expansion-Based Displacement Calculation on FPGA". Thesis, Linköpings universitet, Datorteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-132755.

Testo completo

Abstract (sommario):

This thesis implements a system for calculating the displacement between two consecutive video frames. The displacement is calculated using a polynomial expansion-based algorithm. A unit tested bottoms-up approach is successfully used to design and implement the system. The designed and implemented system is thoroughly elaborated upon. The chosen algorithm and its computational details are presented to provide context to the implemented system. Some of the major issues and their impact on the system are discussed.

Gli stili APA, Harvard, Vancouver, ISO e altri

8

Guidi, Claudia. "Soil organic carbon responses to forest expansion on mountain grasslands". Doctoral thesis, country:DK, 2015. http://hdl.handle.net/10449/25091.

Testo completo

Abstract (sommario):

Grassland abandonment followed by progressive forest expansion is the dominant land-use change in the European Alps. Contrasting trends in soil organic carbon (SOC) stocks have been reported for mountainous regions following forest expansion on grasslands. Moreover, its effects on SOC properties involved into long-term stability are largely unknown. The aim of this PhD thesis was to explore changes in: (i) SOC stocks; (ii) physical SOC fractions and their sensitivity to SOC changes; and (iii) labile carbon (C) in soil and fractions following forest expansion on mountain grasslands. A land-use gradient located in the Southern Alps (Italy) was examined, comprising managed grassland, two transitional phases in which grassland abandonment led to colonization by Picea abies (L.) Karst., and old forest dominated by Fagus sylvatica L. and P. abies. Organic and mineral soil layers were collected within three plots for each successional stage. Soil samples were fractionated according to: (i) aggregate size fractionation, separating aggregates through wet-sieving, and (ii) size-density fractionation, separating stable aggregates from particulate organic matter (POM) non-occluded within aggregates. Changes in labile soil C were assessed by analysis of carbohydrate monomers and by thermal analysis of soil and size-density fractions. Our study showed that mineral SOC stocks were lower in early-stage and old forest (-28% in the top 10 cm of mineral soil) than in managed and abandoned grassland. The SOC accumulation within the organic layers following forest establishment could not fully compensate the mineral SOC stock difference between forest and grassland successional stages. The dimension of aggregates assessed by aggregate size fractionation tended to increase, while SOC allocation to stable aggregates assessed by size-density fractionation decreased following conversion of grassland to forest (e.g from 81 to 59% in the 0-5 cm layer). Higher SOC allocation to POM fraction in the mineral soil, together with changed carbon distribution between mineral and organic soil layers, suggest an overall decrease in physical SOC protection and a concomitant shift to unprotected SOC fractions. The size-density fractions showed higher sensitivity to SOC changes than aggregate size fractions and therefore may be better suited for the detection of SOC changes. Carbohydrate and thermal analyses indicated higher shares of labile soil C in grassland abandoned since 10 years than in managed grassland and forest successional stages. Ratios of 6 microbially to plant-derived carbohydrates decreased from grassland to forest successional stages, and corresponded to decreased SOC allocation to stable aggregates. Forest expansion on mountain grasslands caused a decrease in SOC stocks within the mineral soil and in physically protected SOC fractions, which can be explained by lower accumulation of binding agents of microbial origin. This can have implications for the accumulation of atmospheric CO2 in soil and for the susceptibility of SOC to external disturbances such as management and environmental changes.

Gli stili APA, Harvard, Vancouver, ISO e altri

9

Abed, Ayman A. "Numerical modeling of expansive soil behavior /". Stuttgart : IGS, 2008. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=016534652&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

10

Zein, Abdel Karim Mohammad. "Swelling characteristics and microfabric of compacted black cotton soil". Thesis, University of Strathclyde, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332595.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

11

BELCHIOR, INGRID MILENA REYES MARTINEZ. "BEHAVIOR OF A LIME-TREATED EXPANSIVE SOIL". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=29430@1.

Testo completo

Abstract (sommario):

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
Os principais objetivos desta pesquisa são investigar o efeito da cal hidratada (HL) no comportamento de um solo expansivo, Eagle Ford do Texas (USA), e medir a eficiência do tratamento com cal sobre a redução da expansão através de variações das condições de preparação das amostras. Este estudo envolveu ensaios edométricos e ensaios de centrífuga, que é uma nova técnica desenvolvida pela Universidade do Texas em Austin (EUA). Até o presente trabalho, nenhum estudo tem sido desenvolvido usando esta centrífuga para analisar a redução da expansão em solos expansivos estabilizados. Além disso, nenhum estudo tem medido o melhoramento da eficiência do tratamento com cal devido às variáveis controladas durante a preparação das misturas solo-cal (ou seja, umidade, densidade, período entre a mistura e a compactação e tempo de cura), como também da tensão aplicada. Este trabalho também incluiu investigações sobre modificações das propriedades geotécnicas, composição mineralógica e constituição microestrutural, devido à adição de cal. A partir da análise das curvas de expansão vs. tempo, três valores foram definidos para examinar o comportamento expansivo: o potencial expansivo (Sp) e as inclinações de expansão primária (PSS) e secundária (SSS). A avaliação da eficiência do tratamento com cal, quantificada através do parâmetro Razão da Redução do Potencial Expansivo (SPR), indica: (i) eliminação de 97 por cento de Sp com 4 por cento de HL; (ii) melhoramento do SPR pelo aumento do tempo de cura; (iii) efeito adverso na SPR de períodos longos entre mistura e a compactação; (iv) possibilidade de diminuir a dosagem de cal necessária para reduzir a expansão através do aumento da umidade de compactação e/ou redução da densidade seca de compactação; e (v) dependência da dosagem da cal para prevenir a expansão no nível-g.
The main objectives of this research are to investigate the effect of hydrated lime (HL) treatment on the swelling behavior of a natural expansive soil, Eagle Ford clay from Texas (USA), and to measure the efficiency of lime treatment on swelling reduction due to variations in the condition of specimen preparation. This study involved conventional free swell tests and centrifuge tests, which are a new technique developed by the University of Texas at Austin (USA). So far, no studies have been performed using this centrifuge to analyze the swelling reduction in expansive soils by stabilization treatments. Also, no studies have measured the improving of lime treatment efficiency due to variables controlled during preparation of lime-soil mixtures (i.e. compaction moisture content, compaction dry density, mellowing and curing time), as well as the applied effective stress. This work also involved investigations about modifications of geotechnical properties, mineralogical composition and microstructural constitution due to the addition of lime. From the analysis of the swelling vs. time curves, three values were defined to examine the swelling behavior: the swelling potential (Sp), the primary swelling slope (PSS) and the secondary swelling slope (SSS). Assessment of the lime treatment efficiency, as quantified by the Swelling Potential Reduction Ratio (SPR) indicates: (i) the elimination of 97 per cent of Sp with 4 per cent HL; (ii) SPR enhancement with increasing curing time; (iii) adverse effect of mellowing periods on the SPR; (iv) the possibility to decrease the necessary lime dosage by increasing the compaction moisture and/or reducing the compaction dry density; and (v) dependency of the hydrated lime dosage to prevent swelling on the applied g-level (i.e. applied stress).

Gli stili APA, Harvard, Vancouver, ISO e altri

12

Franco, André Luiz Custódio. "Soil engineering by macroinvertebrates: controls on soil organic matter storage across land use change". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-26052015-165800/.

Testo completo

Abstract (sommario):

Globally land use change (LUC) with increasing in land use intensity has led to a decrease in soil organic matter (SOM). The reduction of soil C stock across LUC has been accompanied by a destabilization of soil structure and increases the soil erosion susceptibility. The destabilized soil structure is also concomitant with a loss of soil biodiversity and in particular, soil macroinvertebrate community. The focus of this dissertation is the effect of LUC with increasing in land use intensity on soil macrofauna, aggregation and SOM allocation. We hypothesized that LUC reduces soil macrofaunal biodiversity and consequently decreases soil engineering processes, resulting in destabilization of soil structure and impairing the ability of soil to physically protect SOM from decomposition inside stable aggregates, finally leading to depleted SOC stocks across LUC. In order to test these hypotheses, we conducted a field survey in 3 chronosequences of land use comprising native vegetation (NV), pasture (PA), and sugarcane crop (SC) in Central-Southern Brazil. This land use sequence provides a gradient of land use intensity and is projected to add 6.4 Mha of new sugarcane areas in Brazil by 2021. At each sampling point soil blocks of 25 X 25 cm and 5 x 5 cm to 10 cm depth were simultaneously collected from 0-10 cm, 10-20 cm, and 20-30 cm soil layers, for macrofauna isolation and aggregate fractionation, respectively. Within a radius of 6 meters around each sampling point, 12 subsamples were also collected from the same soil layers, and combined for total soil C and N concentration. An average reduction of 89% in the density of the soil macrofaunal community was observed when SC replaces PA, and a loss of 39% in the diversity of macrofauna groups. Our findings showed that, over a range of soil textures (16 - 66% clay), such biodiversity loss was strongly correlated with the destabilization of soil structure across LUC, whereas soil texture was not so. These observations consistently indicate that the abundance of detritivore soil animals, especially earthworms and termites, may be a significant predictor of soil structure transformations across LUC in tropical environments. Moreover, the sharp reduction in the abundance of earthworms was strongly positively correlated with the decrease in intra macroaggregate-associated C. As a result, after more than 20 years of sugarcane crop there were losses of 40 and 35% of C and N stocks, respectively, resulting in a rate of C emission of 1.3 Mg ha-1 yr-1. This C loss primarily occurred in the macroaggregate-associated C, as a result of the faster macroaggregate turnover under SC. In summary, the results presented here provide a mechanistic explanation as to why there is soil C depletion when increasing land use intensity in tropical soils: the huge reduction in the abundance of soil engineering invertebrates after LUC impair the ability of soil to physically protect SOM from decomposition inside stable aggregates, and therefore it is a primary mechanism controlling the soil C stocks\' depletion across LUC.
Globalmente mudanças no uso da terra (MUT) com o aumento da intensidade de uso do solo têm levado a uma diminuição da matéria orgânica do solo (MOS). A redução do estoque de C do solo após MUT tem sido acompanhada por uma desestabilização da estrutura do solo e aumento da susceptibilidade a erosão. A desestabilização da estrutura também é concomitante com a perda da biodiversidade do solo e, em particular, da comunidade de macroinvertebrados do solo. O foco deste trabalho é o efeito de MUT com aumento na intensidade de uso do solo sobre a macrofauna do solo, agregação e alocação da MOS. Nossa hipótese é que MUT reduz a diversidade da macrofauna do solo e, conseqüentemente, diminui os processos de engenharia de solo, resultando na desestabilização da estrutura do solo e prejudicando a capacidade do solo para proteger fisicamente a MOS da decomposição dentro de agregados estáveis, finalmente levando a redução dos estoques de C após MUT. Foi realizada uma pesquisa em 3 cronosseqüências de uso da terra que compreendem vegetação nativa (NV), pastagem (PA), e cana-de-açúcar (CA) na região Centro-Sul do Brasil. Esta MUT fornece um gradiente de intensidade de uso do solo e é projetada para adicionar 6,4 Mha de novas áreas de CA no Brasil até 2021. Em cada ponto de amostragem de solo blocos de 25 x 25 cm e 5 x 5 cm a 10 cm de profundidade foram coletados simultaneamente das camadas 0-10 cm, 10-20 cm e 20-30 cm de solo, para isolamento da macrofauna e fracionamento de agregados, respectivamente. Foi observada uma redução média de 89% na densidade da comunidade da macrofauna quando CA substitui PA, e uma perda de 39% da diversidade de grupos. Nossos resultados mostraram que, em um intervalo de texturas do solo (16-66% de argila), tal perda de biodiversidade foi fortemente correlacionada com a desestabilização da estrutura do solo após MUT. Estas observações indicam consistentemente que a abundância de animais detritívoros, especialmente minhocas e cupins, pode ser um preditor significativo de transformações da estrutura do solo em MUT. Além disso, a forte redução na abundância de minhocas foi fortemente e positivamente correlacionada com a diminuição do C alocado intra macroagregados. Como resultado, após mais de 20 anos de cultura de CA houve perdas de 40 e 35% dos estoques de C e N, respectivamente, resultando em uma taxa de emissão de C de 1,3 Mg ha-1 ano-1. Esta perda de C ocorreu principalmente no C associado aos macroagregados, como um resultado da reciclagem mais rápida dos macroagregados sob CA. Em resumo, os resultados aqui apresentados fornecem uma explicação mecanicista a respeito de porque há esgotamento do C do solo quando aumenta-se a intensidade de uso do solo em ambientes tropicais: a enorme redução na abundância de invertebrados \"engenheiros do solo\" após MUT prejudica a capacidade do solo para proteger fisicamente a MOS da decomposição dentro de agregados estáveis, e, portanto, é um mecanismo primário controlando a redução dos estoques de C no solo relacionada a MUT.

Gli stili APA, Harvard, Vancouver, ISO e altri

13

Oliveira, Alice Quintela Lopes. "A legitimidade do direito penal do risco : uma proposta sob as perspectivas do funcionalismo teleológico". Universidade Federal de Alagoas, 2009. http://repositorio.ufal.br/handle/riufal/757.

Testo completo

Abstract (sommario):

The present paper analyzes the...
Fundação de Amparo a Pesquisa do Estado de Alagoas
A presente dissertação analisa a pretensa inadequação e insuficiência de direito penal tradicional diante da complexidade...

Gli stili APA, Harvard, Vancouver, ISO e altri

14

Cherubin, Maurício Roberto. "Soil quality response to land-use change for sugarcane expansion in Brazil". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-16062016-160123/.

Testo completo

Abstract (sommario):

Globally, increasing demands for biofuels have intensified the rate of land-use change (LUC) for expansion of bioenergy crops. In Brazil, the world\'s largest sugarcane-ethanol producer, sugarcane area has expanded by 35% (3.2 Mha) in the last decade. Sugarcane expansion has resulted in extensive pastures being subjected to intensive mechanization and large inputs of agrochemicals, which have direct implications on soil quality (SQ). We hypothesized that LUC to support sugarcane expansion leads to overall SQ degradation. To test this hypothesis we conducted a field-study at three sites in the central-southern region, to assess the SQ response to the primary LUC sequence (i.e., native vegetation to pasture to sugarcane) associated to sugarcane expansion in Brazil. At each land use site undisturbed and disturbed soil samples were collected from the 0-10, 10-20 and 20-30 cm depths. Soil chemical and physical attributes were measured through on-farm and laboratory analyses. A dataset of soil biological attributes was also included in this study. Initially, the LUC effects on each individual soil indicator were quantified. Afterward, the LUC effects on overall SQ were assessed using the Soil Management Assessment Framework (SMAF). Furthermore, six SQ indexes (SQI) were developed using approaches with increasing complexity. Our results showed that long-term conversion from native vegetation to extensive pasture led to soil acidification, significant depletion of soil organic carbon (SOC) and macronutrients [especially phosphorus (P)] and severe soil compaction, which creates an unbalanced ratio between water- and air-filled pore space within the soil and increases mechanical resistance to root growth. Conversion from pasture to sugarcane improved soil chemical quality by correcting for acidity and increasing macronutrient levels. Despite those improvements, most of the P added by fertilizer accumulated in less plant-available P forms, confirming the key role of organic P has in providing available P to plants in Brazilian soils. Long-term sugarcane production subsequently led to further SOC depletions. Sugarcane production had slight negative impacts on soil physical attributes compared to pasture land. Although tillage performed for sugarcane planting and replanting alleviates soil compaction, our data suggested that the effects are short-term with persistent, reoccurring soil consolidation that increases erosion risk over time. These soil physical changes, induced by LUC, were detected by quantitative soil physical properties as well as by visual evaluation of soil structure (VESS), an on-farm and user-friendly method for evaluating SQ. The SMAF efficiently detected overall SQ response to LUC and it could be reliably used under Brazilian soil conditions. Furthermore, since all of the SQI values developed in this study were able to rank SQ among land uses. We recommend that simpler and more cost-effective SQI strategies using a small number of carefully chosen soil indicators, such as: pH, P, K, VESS and SOC, and proportional weighting within of each soil sectors (chemical, physical and biological) be used as a protocol for SQ assessments in Brazilian sugarcane areas. The SMAF and SQI scores suggested that long-term conversion from native vegetation to extensive pasture depleted overall SQ, driven by decreases in chemical, physical and biological indicators. In contrast, conversion from pasture to sugarcane had no negative impacts on overall SQ, mainly because chemical improvements offset negative impacts on biological and physical indicators. Therefore, our findings can be used as scientific base by farmers, extension agents and public policy makers to adopt and develop management strategies that sustain and/or improving SQ and the sustainability of sugarcane production in Brazil.
Globalmente, o aumento da demanda de biocombustíveis têm intensificado a taxa de mudança de uso da terra (MUT) para expansão da produção de culturas para fins energéticos. No Brasil, a área de cana-de-açúcar aumentou 35% (3,2 Mha) na última década. A expansão do cultivo de cana-de-açúcar tem resultado em pastagens extensivas sendo submetidas a intensiva mecanização e ao uso de agroquímicos, implicando diretamente na qualidade do solo (QS). A hipótese testada nesse estudo foi que a MUT resulta na degradação da QS. Para tanto foi conduzido um estudo em três locais na região centro-sul, com objetivo de avaliar as modificações na QS devido a principal sequência de MUT (vegetação nativa - pastagem - cana-de-açúcar) associada a expansão do cultivo de cana-de-açúcar no Brasil. Em cada uso da terra, amostras indeformadas e deformadas de solo foram coletadas nas profundidades de 0- 10, 10-20 e 20-30 cm. Os atributos químicos e físicos do solo foram mensurados através de análises laboratoriais e à campo. Dados de atributos biológicos também foram incluídos no estudo. Inicialmente, os efeitos da MUT foram quantificados individualmente para cada um dos atributos do solo, e em seguida as alterações na QS global foram avaliadas através da Soil Management Assessment Framework (SMAF) e de seis índices de QS (IQS), desenvolvidos usando métodos com complexidade crescente. Os resultados demonstraram que a conversão da vegetação nativa em pastagem extensiva resultou na acidificação do solo, redução dos teores de carbono orgânico (COS) e macronutrientes (especialmente P), e severa compactação do solo, desequilibrando a relação entre ar e água e aumentando a resistência mecânica do solo ao crescimento radicular. Conversão da pastagem em cana-de-açúcar melhorou a qualidade química do solo através da correção da acidez e aumento dos macronutrientes. Apesar dessas melhorias, prolongado período de cultivo de cana-de-açúcar reduziu os teores de COS; e a maioria do P adicionado via fertilizantes acumulou em formas menos lábeis, confirmando o importante papel do P orgânico no fornecimento de P disponível às plantas em solos brasileiros. O cultivo de cana-de-açúcar teve impactos negativos nos atributos físicos do solo menos intensos do que aqueles gerados pelo uso com pastagem. Embora o preparo do solo para plantio e reforma da cana-de-açúcar reduziu a compactação do solo, os dados sugeriram que estes efeitos são de curta duração, ocorrendo a reconsolidação do solo e o aumento dos riscos de erosão ao longo do tempo. As alterações físicas do solo induzidas pela MUT foram detectadas tanto por meio de atributos quantitativos quanto por meio de avaliação visual da estrutura do solo (VESS), um método simples e diretamente aplicado no campo. A SMAF detectou eficientemente as alterações na QS devido a MUT. Além disso, todos os IQS desenvolvidos permitiram ranquear corretamente a QS entre os usos da terra. Assim, recomendamos que IQS mais simples e com melhor relação custo-benefício usando poucos indicadores chaves, tais como: pH, P, K, VESS e COS com ponderação proporcional entre os setores do solo (químico, físico e biológico) sejam usados como protocolo para avaliar a QS nas áreas de produção de cana-de-açúcar. Os resultados obtidos usando a SMAF e os IQS sugeriram que a conversão da vegetação nativa em pastagem extensiva reduziu a QS, degradando indicadores químicos, físicos e biológicos. Por outro lado, a conversão de pastagem em cana-de-açúcar não teve impactos na QS global, uma vez que a melhoria dos atributos químicos compensou os impactos negativos nos indicatores físicos e biológicos. Desta forma, esses resultados poderão ser utilizados como base científica pelos produtores, extencionistas e políticos para orientar estratégias de manejo que mantenham e/ou melhorem a QS e consequentemente a sustentabilidade da produção de cana-de-açúcar no Brasil.

Gli stili APA, Harvard, Vancouver, ISO e altri

15

Henderson, Susan J. "Expansive soil/footing systems incorporating compressible void formers". Thesis, Queensland University of Technology, 1988. https://eprints.qut.edu.au/36466/1/36466_Henderson_1988.pdf.

Testo completo

Abstract (sommario):

Paper-derived void formers for footings have changed little since they were developed nearly three decades ago, when practical understanding of the behaviour of expansive clays and consequent soil-structure interaction was just emerging. In this thesis, current understanding and analytical techniques are applied to investigate the performance of pier-and-beam footings incorporating void formers. Published soil supplemented by a suction data were collated program of sampling below slabs and to provide soil moisture conditions, before construe .~ion, typical of the semi-arid central-southeast Queensland. and after regions of A laboratory test was developed to evaluate the void formers' resistance to concentrated loadings, such as could occur during construction. A suction-water content relationship was used to control moisture in a second test which investigated load-compression behaviour of the void formers at expected in-service conditions. One product was characteristed as the basis of a finite element model to demonstrate the interaction of pressures and movements as the soil wets up and heaves, and to investigate the relative effects of various void former properties. It was shown that the void formers' peak strength at in-service moisture conditions and ease of moisture absorption are critical to the magnitude of uplift pressure transmitted to the slab and that the present design assumption of zero uplift pressure is inappropriate.

Gli stili APA, Harvard, Vancouver, ISO e altri

16

Turmena, Leandro. "O PÚBLICO, O PRIVADO E O ESTADO SOB A LÓGICA DO CAPITAL: A EXPANSÃO DO ENSINO SUPERIOR NO SUDOESTE DO PARANÁ". UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2009. http://tede2.uepg.br/jspui/handle/prefix/1287.

Testo completo

Abstract (sommario):

Made available in DSpace on 2017-07-21T20:31:46Z (GMT). No. of bitstreams: 1 Leandro Turmena.pdf: 3123947 bytes, checksum: 4dc3bc5e750ec1ad33a708df503b829d (MD5) Previous issue date: 2009-07-31
of Paraná in the period of 1967 to 2009. The political and economical determinants of the process of expansion of higher education in this region are analyzed, considering the social organization of work (capitalist relationships of production) and the function of the State in the formation of educational politics. The cutting of the object indicates the origin of the first IES (the decade of 1960) and the proliferation of new courses stemming from the 9394/96 Law of the region. Therefore, the survey is epistemologically set in the method of dialectic historic materialism, more specifically in the categories of totality, of contradiction and of mediation. There first was made a contextualization of the Southwest region of Paraná: historical, geographical, political, economical and higher education data (origin and expansion). Next, it moved in the direction of historical development of higher education in Brazil and in the State of Paraná and the function that the State took on in the historical periods determined. Finally, the relationships between the social organization of work, the State reform and the higher education in the decade of 1990 was analyzed. What showed up from the analyses done was that the expansion of higher education in Southwest Paranà starting from the decade, 1990, is articulated dialectically with the form of capitalistic production. The State takes on the administration and the financing of the demands of the society legislating the form of financing of the openings in the private institutions. Thus, contradictorily there was an offer, even though reduced, of public higher education. The survey also showed that the higher education that expands in the logic of the market is the result of the “market of knowledge”, applied to the formation of complex work in order to attend the logic of he “knowledge for the market” under the ideological discourse of development and of employment, which has attracted middle class educational services, though actually having a crisis in this sector. The survey was explicit that the logics of the capital indicate a “development” of the productive forces based on the formation of higher education for the work market and that there is not the development of the survey and the production of knowledge as its main orientation, at least in the investigated region. Above all, it seeks to capacitate workers for the work market and reserves manual labor for minimal qualification. In theory, the formation in higher education, which was actually investigated, has little to contribute for the formation of critical and capable citizens to carry out the political control of the State middle class.
Esta pesquisa investiga a expansão do ensino superior no Sudoeste do Estado do Paraná no período de 1967 a 2009. Analisou-se os determinantes políticos e econômicos do processo de expansão do ensino superior nesta região, considerando a organização social do trabalho (relações capitalistas de produção) e a função do Estado na formulação das políticas educacionais. O recorte do objeto indica a origem da primeira IES (década de 1960) e a proliferação de novos cursos a partir da Lei 9394/96 na região. Para tanto, a pesquisa está assentada epistemologicamente no método do materialismo histórico dialético, mais especificamente nas categorias da totalidade, da contradição e da mediação. Primeiramente foi feita a contextualização da região Sudoeste do Paraná: dados históricos, geográficos, políticos, econômicos e o ensino superior (origem e expansão). Em seguida apontou-se o desenvolvimento histórico do ensino superior no Brasil e no Estado do Paraná e a função que o Estado assumiu nos determinados períodos históricos. Por fim analisou-se as relações entre a organização social do trabalho, a reforma do Estado e o ensino superior na década de 1990. A partir das análises feitas constatou-se que a expansão do ensino superior no Sudoeste do Paraná a partir da década de 1990 se articula dialeticamente com o modo de produção capitalista. O Estado assume a gestão e o financiamento das demandas da sociedade, legislando de modo a financiar as vagas das instituições privadas. Assim, contraditoriamente houve a oferta, mesmo que reduzida, de ensino superior público. A pesquisa evidenciou também que o ensino superior que se expande na lógica do mercado é fruto do “mercado do conhecimento”, aplicado à formação do trabalho complexo para atender a lógica do “conhecimento para o mercado” sob o discurso ideológico do desenvolvimento e da empregabilidade, o que tem atraído a burguesia de serviços educacionais, embora atualmente haja crise no setor. A pesquisa explicitou que as lógicas do capital indicam um “desenvolvimento” das forças produtivas com base na formação em nível superior para o mercado de trabalho, e que não tem como princípio norteador o desenvolvimento da pesquisa e a produção de conhecimento, pelo menos na região investigada. Acima de tudo busca capacitar trabalhadores para o mercado de trabalho e para a reserva de mão de obra com qualificação mínima. Em tese, a formação em nível superior, na realidade investigada, tem pouco a contribuir para a formação de cidadãos críticos e capazes de exercer o controle político do Estado burguês.

Gli stili APA, Harvard, Vancouver, ISO e altri

17

Zhuang, Peizhi. "Cavity expansion analysis with applications to cone penetration test and root-soil interaction". Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/42772/.

Testo completo

Abstract (sommario):

As one of the most versatile and reliable in-situ devices, cone penetrometers have been extensively used in soil exploration (e.g. soil classification, soil profiling, back-calculation of soil properties etc.) both experimentally and theoretically over the past 80 years. To improve its site accessibility, reduce the required sample size with minimal boundary effects, or model soil penetration by plant roots or earthworms, cone penetrometers with various sizes are often employed both in the field and laboratory. Consequently, size-dependent performance may appear, and this is one of the subjects of this research. A series of cone penetration tests with three sized cone penetrometer (12mm, 6mm, 3mm) on the Leighton Buzzard sand with two fractions (E and C) was performed at the 1g condition. Evident size effects were observed both in the cone tip resistance and shaft friction. To account for the observed size-dependent behaviour, theoretical methods based on the cavity expansion theory were developed in addition to the available experimental findings. Firstly, a size-dependent quasi-static cavity expansion solution was developed by improving the conventional cavity expansion theory incorporating with a strain gradient theory of plasticity. A stiffer response is modelled for a smaller cylindrical/ spherical cavity with this solution. Based on the analogy of cone penetration and quasi-static cavity expansion, the developed size-dependent expansion solution for spherical cavities was employed to quantify the size effect in the cone tip resistance, and fair good agreements were achieved between the theoretical prediction and experimental results. Subsequently, the scale effect observed in shaft friction resistance was explained in terms of the interface frictional strength and mobilised lateral soil stress. The size-dependent interface frictional strength was discussed based on the available experimental data of other researchers, and an improved solution based on the elastic cylindrical cavity expansion solution was derived to quantify the size dependency of the mobilised lateral stress on the shaft. In the light of above discussions, dominating factors influencing the size-dependent behaviours in the cone penetration test are summarised. The other objective of the present research was to model the mechanical interaction between a growing root tip and the surrounding soil. Two elastic solutions for computing the stress and displacement fields around a displacement-controlled ellipse were developed based on the complex variable theory of elasticity and Fourier series method. By assuming the axial cross section of a root tip as a half-ellipse, the two-dimensional soil response to a short-term growing root tip was discussed with the derived elastic solutions. Benefits of radial swelling of the root tip to its axial penetration were summarised, and an approximate analytical method to estimate the soil resistance mobilised by a short-term root growth was suggested and employed in the present root tip-soil interaction analyses. In addition, influences of the additional shear stress in the process of static and quasi-static cavity expansion were analysed with an elastic-perfectly-plastic model. For Tresca materials, a non-equal initial stress field was considered in the static stress solution, and a quasi-static expansion solution was then derived for a cavity deforming in a hydrostatic stress field considering the material compressibility. The static stress solution is capable of calculating the stress redistribution around a circular rotating probe, and the large-strain quasi-static solution may be useful in theoretical predictions of the tip resistance of a rotating penetrometer (or pile) which has been often utilised in needle cone penetration tests for modelling the root tip elongation. Then the introduced methods in above solutions were applied to the static stress analysis of a circular cavity surrounded by the Mohr-Coulomb material under a non-equal stress field. Based on the conformal mapping function proposed by Detournay and Fairhurst (1987), both a loading and unloading analysis were carried out with the derived analytical solution. It can provide a simple method to predict the plastic failure zone and calculate the stress redistribution around a circular excavation (e.g. tunnel, pipeline) either under loading or unloading.

Gli stili APA, Harvard, Vancouver, ISO e altri

18

Lopes, Cassiomar Rodrigue. "Expansão da silvicultura de eucalipto no bioma cerrado: uma análise sob a perspectiva dos fatores físicos e socioeconômicos". Universidade Federal de Goiás, 2013. http://repositorio.bc.ufg.br/tede/handle/tede/3250.

Testo completo

Abstract (sommario):

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2014-10-02T12:37:08Z No. of bitstreams: 2 Dissertação - Cassiomar Rodrigues Lopes - 2013.pdf: 4397463 bytes, checksum: 77e10a2616b5b02b9cfa4d9278944278 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5)
Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-10-02T15:57:02Z (GMT) No. of bitstreams: 2 Dissertação - Cassiomar Rodrigues Lopes - 2013.pdf: 4397463 bytes, checksum: 77e10a2616b5b02b9cfa4d9278944278 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5)
Made available in DSpace on 2014-10-02T15:57:02Z (GMT). No. of bitstreams: 2 Dissertação - Cassiomar Rodrigues Lopes - 2013.pdf: 4397463 bytes, checksum: 77e10a2616b5b02b9cfa4d9278944278 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-07-31
This work presents and discusses the results about the expansion of the cultivation of eucalyptus (Eucalyptus spp) in the Cerrado biome, including the analysis of related variables in this process. The motivation for this research came from the recognition, using data from the Brazilian Institute of Geography and Statistic, of the expansion of this crop, mainly in the state of Mato Grosso do Sul, where it was verified in the last three decades changes in the landscape with the replacement of cattle raising and agriculture. At the same time, there was a regression in eucalyptus plantations in Bahia’s west. It can be argued that this expansion and regression of areas are connected to the presence of forest-based industries in the region that needs this raw material. Therefore, this study sought to identify areas where they are being held eucalyptus plantations in the Cerrado with 2006 census data. These locations were chosen based on these information, and the mapping of the highlighted counties according to the data from the agricultural census. Then it was analyzed the variables physical, political economical and social policies in the producing regions. Based on these features were pointed the prone areas for the expansion of eucalyptus plantation in the Cerrado. In general, the results show that there are a predominance of some characteristics in the choice of areas to be cultivated, as a predominant deep sandly quartzly soils, relief in the class of 0 º to 8 º of declivity and proximity to highways and rivers around 5 km and 3 km, respectively. Another important result of this research, obtained by the intersection of the areas of eucalyptus to the Cerrado and the map of land use (PROBIO), indicates that the expansion of this crop is occurring over areas with remnant Cerrado vegetation.
Neste trabalho são apresentados e discutidos os resultados sobre a expansão do cultivo de eucalipto (Eucalyptus ssp) no bioma Cerrado, incluindo a análise das variáveis relacionadas neste processo. A motivação para esta pesquisa partiu da constatação, através de dados do IBGE, da expansão desta cultura, principalmente no Estado do Mato Grosso do Sul, onde nas últimas três décadas verificou-se mudanças na paisagem com a substituição da pecuária e da agricultura. Ao mesmo tempo, verificou-se uma regressão no plantio de eucalipto na região oeste da Bahia. Pode-se afirmar que esta expansão e regressão das áreas estão ligadas com a presença de indústrias de base florestal na região, que necessitam desta matéria prima. Para tanto, esta pesquisa buscou identificar as áreas onde estão sendo realizados os plantios de eucalipto no Cerrado com dados censitários de 2006. Tais localidades foram escolhidas tendo como base estas informações, sendo realizado o mapeamento dos municípios de destaque segundo os dados do censo agropecuário. Em seguida foram analisadas as variáveis físicas, políticas econômicas e sociais nas regiões produtoras. Com base nestas características foram apontadas as áreas propensas para a expansão do eucalipto no Cerrado. Em geral, os resultados demonstram que existem algumas características em comum nas áreas cultivadas, tais como predomínio de solo arenoquartizoso profundo, relevo com até 0º a 8º de declividade e proximidade de rodovias e rios em torno de 5 km e 3 km, respectivamente. Outro resultado relevante da pesquisa, obtido com a intersecção das áreas de eucalipto para o Cerrado e o mapa de uso da terra (PROBIO), indica que a expansão deste cultivo está ocorrendo sobre áreas de Cerrado remanescente.

Gli stili APA, Harvard, Vancouver, ISO e altri

19

Udukumburage, Rajitha Shehan. "Investigation of climatic-induced ground responses in expansive soils". Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/198195/1/Rajitha%20Shehan_Udukumburage_Thesis.pdf.

Testo completo

Abstract (sommario):

This thesis presents a practical approach for geotechnical practitioners to investigate the climatic-induced ground responses in expansive soils. The method is based on a novel long-term operable instrumented soil column (ISC). This research investigated the applicability of the current displacement models to the Australian context. As a result, the structural damages and maintenance costs due to cracking of light-weight structures founded on such soils can be minimised, and more importantly, the hazards to human lives can be prevented by improved decisions.

Gli stili APA, Harvard, Vancouver, ISO e altri

20

Hamadto, Mohammed El Fatih Mukhtar. "Expansive soil behaviour and the development of a knowledge based system associated with foundations in expansive soils". Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/526.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

21

Baser, Onur. "Stabilization Of Expansive Soils Using Waste Marble Dust". Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610339/index.pdf.

Testo completo

Abstract (sommario):

Expansive soils occurring in arid and semi-arid climate regions of the world cause serious problems on civil engineering structures. Such soils swell when given an access to water and shrink when they dry out. Several attempts are being made to control the swell-shrink behavior of these soils. Soil stabilization using chemical admixtures is the oldest and most widespread method of ground improvement. In this study, waste limestone dust and waste dolomitic marble dust, by-products of marble industry, were used for stabilization of expansive soils. The expansive soil is prepared in laboratory as a mixture of kaolinite and bentonite. Waste limestone dust and waste dolomitic marble dust were added to the expansive soil with predetermined percentage of stabilizer varying from 0 to 30 percent. Grain size distribution, consistency limits, chemical and mineralogical composition, swelling percentage, and rate of swell were determined for the samples. Swelling percentage decreased and rate of swell increased with increasing stabilizer percentage. Also, samples were cured for 7 days and 28 days before applying swell tests. Curing of samples affects swell percentages and rate of swell in positive way.

Gli stili APA, Harvard, Vancouver, ISO e altri

22

Gomes, Ribamar de Jesus. "Estudo geotecnico de um solo superficial da cidade de Bragança Paulista - SP". [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258204.

Testo completo

Abstract (sommario):

Orientador: David de Carvalho
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
Made available in DSpace on 2018-08-09T15:24:02Z (GMT). No. of bitstreams: 1 Gomes_RibamardeJesus_M.pdf: 3281674 bytes, checksum: 135d37dcb38ea7208dfdb87b862c01d7 (MD5) Previous issue date: 2006
Resumo: Estuda-se o comportamento geotécnico de um perfil de solo tropical típico da região de Bragança Paulista - SP. Esse perfil é classificado pela pedologia como um Latossolo Vermelho Amarelo. Para atingir esse objetivo foram realizados ensaios de caracterização, ensaios triaxiais e ensaios edométricos no teor de umidade natural e saturado. Nos ensaios de caracterização constatou-se o comportamento laterítico do solo. Nos ensaios edométricos quando os corpos de prova foram inundados nas tensões normalmente adotadas em projetos de fundações de edificações de pequeno e médio porte, construções características da cidade, constatou -se indícios de expansibilidade e colapsibilidade, apontando para a necessidade de estudos mais aprofundados sobre esses fenômenos em outras localidades do município
Abstract: The survey has the objective to investigate the geotechnical behavior of a typical soil profile at Bragança Paulista city - São Paulo State - Brazil. This profile is classified by the pedology as Red Yellow Oxisoil. To achieve this aim were accomplished characterization geotechnical tests, triaxial tests and consolidation tests. In the characterization tests was proved the lateritic behavior of the soil. In the consolidation tests when the samples were saturated in the tensions normally stipulated in edifications foundations projects at small and medium conveyance the results had pointed colapsible and expansive soil existence at the referred city
Mestrado
Geotecnia
Mestre em Engenharia Civil

Gli stili APA, Harvard, Vancouver, ISO e altri

23

Zuckerman, Shlomit. "The Expansion of Newborn Screening In Israel: Ethical and Social Dimensions". Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1247156923.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

24

Tehrani, Katayoon. "Developing a new instrumented soil column to study climate-induced ground movement in expansive soil". Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/100017/4/Katayoon_Tehrani_Thesis.pdf.

Testo completo

Abstract (sommario):

This project was a step forward in developing an instrumented soil column to enhance the understanding of the behaviour of expansive soil subjected to different climatic conditions. The results of this research can enhance the design of structures which are built on and in expansive soils and will reduce the risk of failures. Also it will lead to cost-effective design and construction of structures such as residential slabs, roads, and shallow depth pipelines on and in expansive soils and providing a significant financial benefit to the community.

Gli stili APA, Harvard, Vancouver, ISO e altri

25

Thomas, Pamela J. "Quantifying Properties and Variability of Expansive Soils in Selected Map Units". Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30441.

Testo completo

Abstract (sommario):

A study of 12 expansive soils in four major physiographic provinces in Virginia was initiated to examine and quantify the relationship between shrink-swell potential, shrink-swell indices, and soil properties. The mineralogy classes, soil series, and (physiographic provinces, parent materials) examined include smectitic -- Jackland and Waxpool (Triassic, diabase), Iredell (Piedmont, hornblende); vermiculitic -- Kelly (Triassic, thermal shale); kaolinitic -- Cecil (Piedmont, granite gneiss), Davidson (Triassic, diabase); and mixed -- Carbo and Frederick (Valley and Ridge, limestone), Craven and Peawick (Coastal Plain, fluvial and marine sediments), and Mayodan and Creedmoor (Triassic, sandstones). Three sites in each of the 12 map units were described and major horizons sampled for physical, chemical, and mineralogical laboratory analysis. An expansive soil rating system, termed the Expansive Soil Index (ESI), was developed using the soil properties best correlated with shrink-swell potential. The sum of swelling 2:1 minerals, swell index, liquid limit, and CEC gave expansive soil potential ratings (ESI) for each soil series. The higher the ESI, the greater the shrink-swell potential. Smectite distributions within the soil profiles were investigated. Smectite concentration in the clay fraction increases with depth in soils formed from diabase and thermally altered shale. Smectite weathers to kaolinite and hydroxy-interlayered vermiculite with increasing proximity to the soil surface thus accounting for the observed decrease in smectite toward the soil surface. The highest amount of smectite from the granite gneiss, limestone, sandstones and shales, and Coastal Plain sediments were in the Bt2 horizon where maximum expression of the argillic horizon occurs. Smectite contents decrease away (upwards and downwards) from the maximum in the Bt2 horizon. A satellite study focused on locating and quantifying the variability within five map units in the Culpeper (Triassic) Basin in northern Virginia. Variability of the shrink-swell indices and related properties are high in all map units. Dissimilar inclusions could adversely affect foundations if a home is sited on both moderate and high shrink-swell soils. Although there is extreme variability in the map units, the variability occurs within the delineations of each map unit. Each delineation within an individual map unit contains similar levels of variability.
Ph. D.

Gli stili APA, Harvard, Vancouver, ISO e altri

26

Long, Xiaoyan. "Prediction of shear strength and vertical movement due to moisture diffusion through expansive soils". Texas A&M University, 2006. http://hdl.handle.net/1969.1/4313.

Testo completo

Abstract (sommario):

This dissertation presents an investigation of engineering behavior of expansive soils. An analytical study was undertaken for the development and modification of a Windows-based two-dimensional finite element computer program FLODEF that performs a sequentially coupled flow-displacement analysis for the prediction of moisture diffusion and the induced volume change in soils supporting various elements of civil infrastructure. The capabilities of the model are illustrated through case studies of shear strength envelope forecast and parametric studies of transient flow-deformation prediction in highway project sites to evaluate the effectiveness of engineering treatment methods to control swell-shrink deformations beneath highway pavements. Numerical simulations have been performed to study the field moisture diffusivity using a conceptual model of moisture diffusion in a fractured soil mass. A rough correlation between field and the laboratory measurements of moisture diffusion coefficients has been presented for different crack depth patterns.

Gli stili APA, Harvard, Vancouver, ISO e altri

27

Zhang, Heng, e 張恒. "Breaking the boundary: towards a spatial integration of new urban expansion and old city in Dapeng, Shenzhen". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41668935.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

28

Liu, Yunlong. "Interpretation of Load Transfer Mechanism for Piles in Unsaturated Expansive Soils". Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/38804.

Testo completo

Abstract (sommario):

Water infiltration associated with natural precipitation events or other artificial activities such as pipe leaks in expansive soils significantly influence the engineering properties; namely, coefficient of permeability, shear strength and volume change behavior. For this reason, it is challenging to design or construct geotechnical infrastructure within or with expansive soils. Several billions of dollars losses, world-wide, can be attributed to the repairing, redesigning and retrofitting of infrastructure constructed with or within expansive soils, annually. Piles are widely used as foundations in expansive soils extending conventional design procedures based on the principles of saturated soil mechanics. However, the behavior of piles in unsaturated expansive soils is significantly different from conventional non-expansive saturated soils. Three significant changes arise as water infiltrates into expansive soil around the pile. Firstly, soil volume expansion contributes to ground heave in vertical direction. Secondly, volume expansion restriction leads to development of the lateral swelling pressure resulting in an increment in the lateral earth pressure in the horizontal direction. Thirdly, pile-soil interface shear strength properties change due to variations in water content (matric suction) of the surrounding soil. These three changes are closely related to matric suction variations that arise during the water infiltration process. For this reason, a rational methodology is necessary for the pile load transfer mechanism analysis based on the mechanics of unsaturated soils. Studies presented in this thesis are directed towards developing simple methods to predict the load transfer mechanism changes of piles in expansive soils upon infiltration. More emphasis is directed towards the prediction of the pile mechanical behavior which includes the pile head load-displacement relationship, the pile axial force (shaft friction) distribution and the pile base resistance using unsaturated mechanical as a tool. The function of matric suction as an independent stress state variable on the mechanical behavior pile is highlighted. More specifically, following studies were conducted: (i) Previous studies on various factors influencing the load transfer mechanisms of piles in unsaturated expansive soils are summarized and discussed to give a background of current research. More specifically, state-of-the-art reviews are summarized on the application of piles in expansive soils, mobilization of lateral swelling pressure, mobilization of unsaturated pile-soil interface shear strength and methods available for the load transfer analysis of piles in expansive soils. (ii) Employing unsaturated soil mechanics as a tool, theoretical methods are proposed for estimating the lateral earth pressure variations considering the mobilization of lateral swelling pressure. The proposed methods are verified using two large-scale laboratory studies and two field studies from published literatures. (iii) The shear displacement method and load transfer curve methods used traditionally for pile load transfer mechanisms analysis for saturated soils were modified to extend their applications for unsaturated expansive soils. The influence of volume change characteristics and unsaturated soil properties on unsaturated expansive soils are considered in these methods. The validation of the modified shear displacement method and modified load transfer curve method were established using a large-scale model test performed in the geotechnical engineering lab of University of Ottawa and a field case study results from the published literature. (iv) A large-scale model pile infiltration test conducted in a typical expansive soil from Regina in Canada in the geotechnical lab of University of Ottawa is presented and interpreted using the experimental data of volumetric water content suction measurements and shear strength data. The results of the comprehensive experiment studies are also used to validate the proposed modified shear displacement method and modified load transfer curve method achieving reasonable good comparisons. The proposed modified shear displacement method and modified load transfer curve method are simple and require limited number soil properties including the soil water characteristic curve (SWCC), matric suction profile upon wetting and drying and some soil physical properties. Due to these advantages, they can be easily and conveniently applied in engineering practice for prediction of the mechanical behavior of piles in unsaturated expansive soils, which facilitate practicing engineers to produce sound design of pile foundation in unsaturated expansive soils in a simplistic manner.

Gli stili APA, Harvard, Vancouver, ISO e altri

29

Sampaio, Juliana Silva de Carvalho. "Análise do modo de expansão recente das multinacionais no Brasil sob a ótica da teoria dos ativos complementares". reponame:Repositório Institucional do FGV, 2015. http://hdl.handle.net/10438/13407.

Testo completo

Abstract (sommario):

Submitted by Juliana Sampaio (jsampaio82@gmail.com) on 2015-02-23T14:50:06Z No. of bitstreams: 1 Dissertação Juliana Sampaio - Versão Final.pdf: 553042 bytes, checksum: 5f5e442204c8a6a912bf21c01f7868fe (MD5)
Rejected by Renata de Souza Nascimento (renata.souza@fgv.br), reason: Prezada Juliana, boa noite Seu trabalho foi rejeitado por não estar de acordo com as normas da ABNT. Encaminhei por e-mail o que deve ser alterado (Somente alguns detalhes). Att Renata on 2015-02-23T22:52:02Z (GMT)
Submitted by Juliana Sampaio (jsampaio82@gmail.com) on 2015-02-23T23:59:07Z No. of bitstreams: 1 Dissertação Juliana Sampaio - Versão Final.pdf: 553115 bytes, checksum: c7d8f3a68dcbf604051728b13fc52f6f (MD5)
Approved for entry into archive by Renata de Souza Nascimento (renata.souza@fgv.br) on 2015-02-24T00:18:39Z (GMT) No. of bitstreams: 1 Dissertação Juliana Sampaio - Versão Final.pdf: 553115 bytes, checksum: c7d8f3a68dcbf604051728b13fc52f6f (MD5)
Made available in DSpace on 2015-02-24T13:41:33Z (GMT). No. of bitstreams: 1 Dissertação Juliana Sampaio - Versão Final.pdf: 553115 bytes, checksum: c7d8f3a68dcbf604051728b13fc52f6f (MD5) Previous issue date: 2015-01-26
O presente estudo analisa o modo de expansão das multinacionais no Brasil, país emergente e de dimensões continentais que apresenta enormes desigualdades regionais. Assim, foram analisadas as estratégias de expansão dos dez maiores grupos estadunidenses no Brasil entre 2004 e 2013, sob a ótica das teorias tradicionais de internacionalização e da teoria dos ativos complementares de Hennart. Verificou-se que as diferentes características regionais brasileiras levam as multinacionais a realizarem aquisições quando iniciam atividades em novas regiões. Ademais, foi constatado que outros fatores, como dificuldades intrínsecas aos setores de atuação e a entrada do grupo multinacional em novas atividades que não a sua predominante, afetam o modo de expansão das multinacionais, levando-as a realizar aquisições e joint ventures. Tais aquisições e joint ventures são explicadas pela dificuldade das multinacionais em acessar ativos complementares locais, em conformidade à teoria de Hennart. Por outro lado, e em contrariedade às teorias tradicionais, foi verificado que a experiência das multinacionais no Brasil nem sempre influencia o seu comprometimento nos países hospedeiros, levando ao estabelecimento de subsidiárias integrais.
This work analyzes the expansion decision made by multinational groups in Brazil, an emerging nation showing sizeable regional differences. We analyzed the expansion strategies of the 10 major US groups in Brazil between 2004 and 2013 based on traditional local internationalization theories and Hennart’s bundling model. We found evidence that the different Brazilian regional characteristics cause multinationals to carry out acquisitions when they need to enter in a new region. Also, we found that Brazilian market factors such as concentration, growth, industries’ intrinsic features and the engagement in new activities affect the expansion mode of multinationals, causing such corporations to carry out acquisitions and establish joint ventures. The acquisitions and joint ventures are explained by the difficulty in obtaining access to local complementary assets in these specific cases, a result in line with Hennart's assertions. On the other hand, we noticed that the experience of multinationals in Brazil not always influences its commitment in the host countries and gives rise to the establishment of wholly-owned subsidiaries.

Gli stili APA, Harvard, Vancouver, ISO e altri

30

Barthur, Ranganath. "Design of residential footings built on expansive soil using probabilistic methods /". Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09ENS/09ensb287.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

31

Celeita-Rodríguez, Nathalia. "Comparação da acurácia diagnóstica de índices dinâmicos e estáticos de pré-carga para predição da fluido-responsividade em cães anestesiados com isoflurano, sob ventilação mecânica". Botucatu, 2020. http://hdl.handle.net/11449/192487.

Testo completo

Abstract (sommario):

Orientador: Francisco José Teixeira Neto
Resumo: Objetivo: Comparar a acurácia diagnóstica da variação da pressão de pulso (VPP), variação do volume sistólico mensurada através do análise de contorno de pulso (VVSACP), índice de variabilidade pletismográfica (IVP), pressão venosa central (PVC) e índice do volume diastólico final global mensurado pela técnica de termodiluição transpulmonar (GEDVITDTP) para predizer a fluido-responsividade em cães. Animais: Quarenta cadelas saudáveis (13,8–26,8 kg) submetidas a ovário-salpingo-histerectomia. Métodos: A anestesia foi mantida com isoflurano sob ventilação mecânica com volume controlado (volume corrente 12 mL/kg, pausa inspiratória 40%, relação inspiração/expiração: 1:1,5). O débito cardíaco e o volume sistólico foram obtidos pela técnica de termodiluição transpulmonar através de um cateter inserido na artéria femoral. A fluido-responsividade (FR) foi avaliada por uma prova de carga (solução de Ringer com lactato, 20 mL/kg durante 15 minutos), administrada uma vez (n = 21) ou duas vezes (n = 18) antes da cirurgia. Respondedores a volume foram definidos como indivíduos onde o VS mensurado pela técnica de termodiluição transpulmonar, elevou-se acima de 15% após a última prova de carga. Resultados: Dos 39 animais incluídos no estudo, 21 cães foram classificados como respondedores e 18 não respondedores ao último desafio volêmico. As áreas sob as curvas de características de operação do receptor (AUROC) foram de 0,976, 0,906, 0,868 e 0,821 para VPP, IVP, PVC e VVSACP, respectivament... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Objective: To compare the diagnostic accuracy of pulse pressure variation (PPV), stroke volume variation from pulse contour analysis (SVVPCA), plethysmographic variability index (PVI), central venous pressure (CVP) and global end-diastolic volume index measured by transpulmonary thermodilution (GEDVITPTD) to predict fluid responsiveness (FR) in dogs. Animals: A group of 40 bitches (13.8–26.8 kg) undergoing ovariohysterectomy. Methods: Anesthesia was maintained with isoflurane under volume-controlled ventilation (tidal volume 12 mL/kg; inspiratory pause during 40% of inspiratory time; inspiration: expiration ratio 1:1.5). Transpulmonary thermodilution cardiac output was recorded through a femoral artery catheter. FR was evaluated by a fluid challenge (lactated Ringer's, 20 mL kg over 15 minutes) administered once (n = 21) or twice (n = 18) before surgery. Individuals were responders if stroke volume index measured by transpulmonary thermodilution increased >15% after the last fluid challenge. Results: Of the 39 animals studied, 21 were responders and 18 were nonresponders. Area under the receiver operating characteristics curve (AUROC) was 0.976, 0.906, 0.868 and 0.821 for PPV, PVI, CVP and SVVPCA, respectively (p < 0.0001 from AUROC = 0.5). GEDVITPTD failed to predict FR (AUROC: 0.660, p = 0.078). Best cut-off thresholds discriminating responders and nonresponders, with respective zones of diagnostic uncertainty (gray zones) were: PPV >16% (15–16%), PVI >11% (10–13%), SVVPCA ... (Complete abstract click electronic access below)
Doutor

Gli stili APA, Harvard, Vancouver, ISO e altri

32

Adem, Hana Hussin. "Modulus of Elasticity Based Method for Estimating the Vertical Movement of Natural Unsaturated Expansive Soils". Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/31910.

Testo completo

Abstract (sommario):

Expansive soils are widely distributed in arid and semi-arid regions around the world and are typically found in a state of unsaturated condition. These soils are constituted of the clay mineral montmorillonite that is highly active and contributes significantly to volume changes of soils due to variations in the natural water content conditions. The volume changes of expansive soils often cause damage to lightly loaded structures. The costs associated with the damage to lightly loaded structures constructed on expansive soils in the United States alone were estimated as $2.3 billion per year in 1973, which increased to $13 billion per year by 2009. In other words, these damages have increased more than five fold during the last four decades. Similar trends in damages were also reported in other countries (e.g., Australia, China, France, Saudi Arabia, United Kingdom, etc.). Numerous methods have been proposed in the literature over the past 50 years for the prediction of the volume change movement of expansive soils. However, the focus of these methods has been towards estimating the maximum potential heave, which occurs when soils attain the saturation condition. The results of heave estimation considering saturated soil conditions are not always useful in engineering practice. This is because most of damages due to expansive soils often occur prior to reaching the saturation condition. A reliable design of structures on expansive soils is likely if the anticipated soil movements in the field can be reliably estimated over time, taking into account the influence of environmental factors. Limited studies are reported in the literature during the past decade in this direction to estimate/predict the expansive soil movements over time. The existing methods, however, suffer from the need to run expensive and time consuming tests. In addition, verification of these studies for different natural expansive soils has been rather limited. A simple approach, which is referred to as a modulus of elasticity based method (MEBM), is proposed in this study for the prediction of the heave/shrinkage movements of natural expansive soils over time. The proposed MEBM is based on a simplified constitutive relationship used for the first time to estimate the vertical soil movements with respect to time in terms of the matric suction variations and the corresponding values of the modulus of elasticity. The finite element program VADOSE/W (Geo-Slope 2007) for simulating the soil-atmospheric interactions is used as a tool to estimate the changes in matric suction over time. A semi-empirical model that was originally proposed by Vanapalli and Oh (2010) for fine-grained soils has been investigated and extended for unsaturated expansive soils to estimate the variation of the modulus of elasticity with respect to matric suction in the constitutive relationship of the proposed method. The MEBM has been tested for its validity in five case studies from the literature for a wide variety of site and environmental conditions, from Canada, China, and the United States. For each case study, factors influencing the volume change behavior of soils, such as climate conditions, soil cracks, lawn irrigation, and cover type (pavement, vegetation), are successfully modeled over the period of each simulation. The proposed MEBM provides good predictions of soil movements with respect to time for all the case studies. The MEBM is simple and efficient for the prediction of vertical movements of natural expansive soils underlying lightly loaded structures. In addition, a new dimensionless model is also proposed, based on the dimensional analysis approach, for the estimation of the modulus of elasticity which can also be used in the constitutive relationship of the MEBM. The dimensional model is rigorous and takes into account the most significant influencing parameters such as matric suction, net confining stress, initial void ratio, and degree of saturation. This model provides a comprehensive characterization of the modulus of elasticity of expansive soils under unsaturated conditions for different scenarios of loading conditions (i.e., both lightly and heavily loaded structures). The results of the present study are encouraging for proposing guidelines based on further investigations and research studies for the rational design of pavements, shallow and deep foundations placed on/in expansive soils using the mechanics of unsaturated soils.

Gli stili APA, Harvard, Vancouver, ISO e altri

33

Demirbas, Gunes. "Stabilization Of Expansive Soils Using Bigadic Zeolite (boron By-product)". Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610671/index.pdf.

Testo completo

Abstract (sommario):

Expansive soils are a worldwide problem that poses several challenges for civil engineers. Such soils swell when given an access to water and shrink when they dry out. The most common and economical method for stabilizing these soils is using admixtures that prevent volume changes. In this study the effect of using Bigadic zeolite (boron by-product) in reducing the swelling potential is examined. The expansive soil is prepared in the laboratory by mixturing kaolinite and bentonite. Bigadic zeolite (boron by-product) is added to the soil at 0 to 25 percent by weight. Grain size distribution, Atterberg limits and swell percent and rate of swell of the mixtures are determined. Specimens are cured for 7 and 28 days. As a result of the experimental study, it was seen that addition of Bigadic zeolite (boronby-product) decreased swelling potential and rate of swell of the artificially prepared expansive soil specimen at laboratory conditions. The swell percentage and rate of swell of the stabilized specimens are affected positively by curing.

Gli stili APA, Harvard, Vancouver, ISO e altri

34

Oliveira, Dener Marcio da Silva. "Soil organic matter dynamics in pasture-sugarcane land use conversions in south-central Brazil". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-19102017-141335/.

Testo completo

Abstract (sommario):

Land use change (LUC) induces modifications on soil organic matter (SOM), which is one of the main source of uncertainty in life cycle assessments of biofuels. In Brazil, currently the world largest producer of sugarcane and second biggest producer of bioethanol, the potential negative effects of LUC has raised doubts about the sugarcane ethanol as a sustainable option. Recently, most of sugarcane expansion has been placed over extensive pastures. Therefore, we conducted a field study within the south-central Brazil, the largest sugarcane-producing region in the world, to evaluate the effects of the most common LUC sequence in sugarcane expansion areas (i.e., conversions from native vegetation to pasture and from pasture to sugarcane) on SOM. Our main hypothesis is that the conversion of degraded pastures to unburnt sugarcane enhance SOM quantity and quality from sites in Brazil. Long-term conversion from native vegetation to pasture induced significant C stock losses (1.01 Mg ha-1 yr-1). In contrast, the conversion from pasture to sugarcane increased C stocks at a rate of 1.97 Mg ha-1 yr-1 down to 0-1.0 m depth. In addition, our findings indicated that SOM assessments restricted to the surface soil layers can generate bias in studies regarding LUC. The main difference in SOM molecular composition undergoing the conversion pasture-sugarcane was the notably higher contribution from compounds associated to fresh litter inputs in sugarcane areas, probably related to the high litter input in sugarcane fields under green management in Brazil. The conversion of areas under native vegetation to pasture decreases both the labile C (LC) and the C management index (CMI), whilst the conversion of pasture to sugarcane increased the CMI according to all evaluated methods. Additionally, the method used to quantify LC and CMI is critical to infer about the LUC effects on SOM. The DayCent model estimated that the conversion native vegetation-pasture caused C losses of 0.34±0.03 Mg ha-1 yr-1, whilst the conversion pasture-sugarcane resulted in C gains of 0.16±0.04 Mg ha-1 yr-1 down to 0.3 m depth. Moreover, simulations showed C decreases of 0.19±0.04 Mg ha-1 yr-1 in sugarcane areas with straw removal for second-generation (2G) ethanol production. However, our analysis suggested that adoption of some best management practices can mitigate these losses, highlighting the application of organic amendments (+0.14±0.03 Mg C ha-1 yr-1). Overall, our study showed that the conversion of pastures to sugarcane has positive effects on SOM quantity and quality, increasing the C savings of Brazilian sugarcane ethanol. Moreover, our findings endorse the potential of sugarcane production to partially recover SOM in degraded pastures. However, most of these gains greatly depends on the high litter input in sugarcane fields under green management, and straw removal for 2G ethanol production is likely to potentially affect SOM in areas of sugarcane expansion in Brazil. Finally, based on land availability and positive effects on SOM, we believe that stakeholders involved with the governance of bioethanol expansion should consider ways to incentivize sugarcane expansion on degraded pastures in Brazil.
Alterações na matéria orgânica do solo (MOS) associadas à mudança de uso da terra (MUT) estão entre as principais fontes de incerteza em avaliações do ciclo de vida dos biocombustíveis. No Brasil, atualmente o maior produtor de cana-de-açúcar e o segundo maior produtor de bioetanol do mundo, os possíveis efeitos negativos da MUT geram questionamentos sobre a efetividade do bioetanol como uma opção sustentável. Grande parte da expansão da cana-de-açúcar ocorre em áreas de pastagem. Nesse sentido, conduziu-se um estudo no Centro-Sul do Brasil, a maior região produtora de cana-de-açúcar do mundo, objetivando-se avaliar os efeitos da MUT vegetação nativa - pastagem - cana-de-açúcar na MOS. A principal hipótese é que a conversão de pastagens degradadas para o cultivo da cana-de-açúcar melhore a qualidade e a quantidade da MOS. A conversão da vegetação nativa para pastagem induz significativas perdas de C no solo (1,01 Mg ha-1 ano-1). Já a conversão dessas pastagens para cana-de-açúcar associa-se a ganhos de C, a uma taxa de 1,97 Mg ha-1 ano-1 até 1m de profundidade. Além disso, avaliações da MOS restritas a camadas superficias relacionam-se a indesejáveis vieses em estudos de MUT. A principal diferença na composição molecular da MOS após a conversão de pastagens para cana-de-açúcar é o aumento na contribuição de formas menos estáveis de C, aspecto associado a alta adição de material vegetal ao solo em áreas de cana-de-açúcar sem queima. A conversão da vagetação nativa para pastagem diminui o C lábil (CL), bem como o índice de manejo de C (IMC), enquanto a conversão da pastagem para a cana-de-açúcar aumenta o IMC de acordo com todos os métodos avaliados. Nesse sentido, o método utilizado para quantificar o CL e o IMC é determinante ao se inferir sobre os efeitos da MUT na MOS. O modelo DayCent estimou que a conversão vegetação nativa-pastagem associa-se a perdas de C no solo de 0,34±0,03 Mg ha-1 ano-1, enquanto a conversão pastagem - cana-de-açúcar associa-se a ganhos de C a 0,16±0,04 Mg ha-1 ano-1 na camada de 0-0,3 m. Além disso, simulações mostraram decréscimos de 0,19±0,04 Mg ha-1 ano-1 do C do solo nas áreas de cana-de-açúcar com remoção de palha para produção de etanol de segunda gereção (2G). No entanto, a adoção de algumas práticas de manejo podem mitigar essas perdas, com destaque para a aplicação de vinhaça e torta de filtro (+0,14±0,03 Mg C ha-1 ano-1). Nosso estudo mostrou que a conversão de pastagens para cana-de-açúcar apresenta efeitos positivos na qualidade e na quantidade da MOS, favorecendo o balanço de C do etanol brasileiro. Nossos resultados endorsam o potencial da cana-de-açúcar em recuperar, parcialmente, os estoques de C em pastagens degradadas. No entanto, esses ganhos são altamente dependentes da alta adição de resíduos vegetais nas áreas de cana-de-açúcar, e a remoção de palha para produção de etanol 2G poderá afetar a MOS em áreas de expansão. Por fim, com base na disponibilidade de áreas e nos efeitos positivos sobre a MOS, meios para estimular a expansão da cana-de-açúcar em áreas de pastagem degradadas no Brasil devam ser considerados.

Gli stili APA, Harvard, Vancouver, ISO e altri

35

Srinivasamurthy, Lakshmikanth. "Initial Swelling Mechanism of Expansive Clays: A Molecular Dynamics Study". Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26647.

Testo completo

Abstract (sommario):

Expansive soils are widely found in many parts of the world. Highly active smectite clay mineral Montmorillonite is the major constituent in these clays and can expand or contract up to 15 times of their original volume. Constrained swelling exert large amount of stress causing damage to structures, pavements etc. These clays are also used as barrier materials, Nano-materials in polymer clay Nano composites and drug delivery systems. Several factors influence the swelling potential such as water content, density, voids, electrolyte content and cation exchange capacity. However, molecular scale mechanisms that control swelling behavior in these clays need to be understood. Objectives of this research are to provide an insight into mechanisms that result in swelling of these clays. Molecular modeling is used to build and study solvation of Na-Montmorillonite system. Trajectories of water molecules are captured and the evolutions of interaction energies with swelling are calculated.

Gli stili APA, Harvard, Vancouver, ISO e altri

36

Zhan, Liangtong. "Field and laboratory study of an unsaturated expansive soil associated with rain-induced slope instability /". View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202003%20ZHAN.

Testo completo

Abstract (sommario):

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003.
Includes bibliographical references (leaves 471-490). Also available in electronic version. Access restricted to campus users.

Gli stili APA, Harvard, Vancouver, ISO e altri

37

Catafesta, Jadna. "Comportamento estrutural sob altas pressões de materiais com expansão térmica anômala". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/28173.

Testo completo

Abstract (sommario):

Nesta tese foi investigado o comportamento sob altas pressões de compostos com estrutura poliedral aberta que apresentam expansão térmica anômala. A presença de vazios e a alta flexibilidade deste tipo de estrutura, quando submetidos a condições extremas, como altas pressões e temperaturas, podem apresentar uma série de fenômenos físicos interessantes, incluindo transições de fase estruturais e amorfização. A relação entre a expansão térmica anômala e a amorfização induzida por altas pressões foi objeto de estudo através de compostos com diferentes especificidades da estrutura de partida, a saber, ZrW2O8, Fe[Co(CN)6], Zn(CN)2 e Ag3[Co(CN)6]. Os diferentes materiais foram submetidos a altas pressões e temperatura com o auxílio da câmara de bigornas de diamantes e das câmaras toroidais de grande volume. Análises in situ sob aquecimento do ZrW2O8 revelaram que este composto recristaliza inicialmente para fase b, estável em altas temperaturas e, posteriormente, para fase a-ZrW2O8. Este comportamento está de acordo com uma fase amorfa formada pelo congelamento dos modos de unidades rígidas de baixa energia e retida pela formação de novas ligações W-O. Os estudos dos cianetos revelaram que sob pressão estes compostos apresentam a formação de uma fase amorfa ou altamente desordenada como conseqüência de uma decomposição cineticamente impedida. Os resultados obtidos confirmam a correlação entre a amorfização induzida por altas pressões e a expansão térmica anômala. Porém, eles indicam que os mecanismos físicos responsáveis pelos dois fenômenos podem ser distintos e, dependendo das especificidades da estrutura de partida dos compostos de estrutura poliedral aberta, cada material pode perder sua ordem de longo alcance por diferentes caminhos.
In this work we have investigated the high pressure behavior of compounds with open framework structures that exhibit anomalous thermal expansion. The presence of voids and the high flexibility of this kind of structure open the possibility of interesting physical phenomena, when these compounds are submitted to high pressure or temperature, including structural phase transitions and amorphization. The proposed relationship between anomalous thermal expansion and pressure induced amorphization was studied for materials with different open framework structures: ZrW2O8, Fe[Co(CN)6], Zn(CN)2, and Ag3[Co(CN)6]. These materials were subjected to high pressure using diamond anvil cells or high volume toroidal chambers. The in situ analysis of amorphous ZrW2O8, under heating at atmospheric pressure, revealed that this compound crystallizes initially to the b phase, stable at high temperatures, and then transforms under cooling to a-ZrW2O8. This behavior is in agreement with an amorphous phase formed by the freezing of low-energy rigid unit vibrational modes and retained by the formation of new connections W-O. The study of cyanides showed that under high pressure these compounds transform to a highly disordered or to an amorphous phase as a consequence of a kinetically hindered pressure induced decomposition. The obtained results confirm the correlation between pressureinduced amorphization and anomalous thermal expansion. However, they indicate that the physical mechanisms behind the two phenomena can be quite distinct and, depending on specific details of the starting open framework structure, each material can lose its long range ordering in a different way.

Gli stili APA, Harvard, Vancouver, ISO e altri

38

Lucian, Charles. "Geotechnical Aspects of Buildings on Expansive Soils in Kibaha, Tanzania : Preliminary Study". Licentiate thesis, Stockholm : Division of soil and rock mechanics, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4056.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

39

Tu, Hongyu. "Prediction of the Variation of Swelling Pressure and 1-D Heave of Expansive Soils with respect to Suction". Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32515.

Testo completo

Abstract (sommario):

The one-dimensional (1-D) potential heave (or swell strain) of expansive soil is conventionally estimated using the swelling pressure and swelling index values which are determined from different types of oedometer test results. The swelling pressure of expansive soils is typically measured at saturated condition from oedometer tests. The experimental procedures of oedometer tests are cumbersome as well as time-consuming for use in conventional geotechnical engineering practice and are not capable for estimating heave under different stages of unsaturated conditions. To alleviate these limitations, semi-empirical models are proposed in this thesis to predict the variation of swelling pressure of both compacted and natural expansive soils with respect to soil suction using the soil-water characteristic curve (SWCC) as a tool. An empirical relationship is also suggested for estimating the swelling index from plasticity index values, alleviating the need for conducting oedometer tests. The predicted swelling pressure and estimated swelling index are then used to estimate the variation of 1-D heave with respect to suction for expansive soils by modifying Fredlund (1983) equation. The proposed approach is validated on six different compacted expansive soils from US, and on eight field sites from six countries; namely, Saudi Arabia, Australia, Canada, China, US, and the UK. The proposed simple techniques presented in this thesis are friendly for the practitioners for using when estimating the heave in unsaturated expansive soils.

Gli stili APA, Harvard, Vancouver, ISO e altri

40

Cetiner, Sertan Isik. "Stabilization Of Expansive Soils By Cayirhan Fly Ash And Desulphogypsum". Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/1119387/index.pdf.

Testo completo

Abstract (sommario):

Expansive soils are one of the most serious problems which the foundation engineer faces. Several attempts are being made to control the swell-shrink behavior of these soils. One of the most effective and economical methods is to use chemical additives. Fly ash and desulphogypsum, both of which are by-products of coal burning thermal power plants, are accumulating in large quantities all over the world and pose serious environmental problems. In this study, the expansive soil was stabilized using the fly ash and desulphogypsum obtained from Ç
ayirhan Thermal Power Plant. Fly ash and desulphogypsum were added to the expansive soil from 0 to 30 percent. Lime was used to see how efficient fly ash and desulphogypsum on expansive soil stabilization were, and was added to the expansive soil from 0 to 8 percent. The properties obtained were chemical composition, grain size distribution, consistency limits, swelling percentage, and rate of swell. Fly ash, desulphogypsum, and lime added samples were cured for 7 days and 28 days, after which they were subjected to free swell tests. Swelling percentage decreased and rate of swell increased with increasing stabilizer percentage. Curing resulted in further reduction in swelling percentage and further increase in rate of swell. 25 percent and 30 percent fly ash and desulphogypsum additions reduced the swelling percentage to levels comparable to lime stabilization.

Gli stili APA, Harvard, Vancouver, ISO e altri

41

Cleall, Peter John. "An investigation of the thermo/hydraulic/mechanical behaviour of unsaturated soils, including expansive clays". Thesis, Cardiff University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389795.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

42

Kuckartz, Bruno Tomasi. "Análise de expansão de cava com múltiplas restrições de superfície sob incerteza geológica". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/163404.

Testo completo

Abstract (sommario):

A operação e gerência de empreendimentos mineiros são tarefas normalmente difíceis e complexas. Para otimizar toda a operação, os engenheiros precisam lidar com muitos aspectos técnicos e restrições, como a modelagem geológica, estimativa de reservas, determinação da necessidade de blendagem, projeto das cavas ótimas e operacionais, custos operacionais, questões ambientais, entre outros. Nesse sentido, o posicionamento de infraestruturas de superfície é um dos pontos críticos dentro do planejamento de mina. Aproximar as estruturas da cava, com o intuito de reduzir custos operacionais, pode interferir em eventuais expansões da cava em novos e favoráveis cenários. Nesses casos, impactos no valor presente líquido (VPL) do projeto são inevitáveis e precisam ser tratados tecnicamente, avaliando um grande número de cenários alternativos para delinear uma estratégia que incremente a lucratividade do projeto. O objetivo deste estudo é avaliar, por meio de comparações de VPL entre diferentes cenários de múltiplas restrições de superfície, sob incerteza geológica, a possibilidade de mover pilhas de estéril e outras infraestruturas de suas atuais posições e/ou definir prioridades e mensurar o impacto que cada restrição representa na lucratividade do projeto. A metodologia foi aplicada a uma mina de fosfato para ilustrar como determinar a melhor alternativa em uma perspectiva de planejamento de mina de longo prazo. Utilizando o método de cavas híbridas, aplicado ao modelo de teores simulados, foi possível identificar zonas de probabilidade de ocorrência dentro da cava matemática, o que forneceu informações cruciais para auxiliar na tomada de decisão a respeito da necessidade de relocação de estruturas.
The operation and management of mining enterprises are usually difficult and complex tasks. To optimize the entire operation the engineers must deal with several technical aspects and constraints, such as orebody modelling, reserves estimation, determination of blending necessity, optimum and operational pit designs, operational costs, environmental issues, among others. In this sense, locating surface infrastructures is one of the most critical mine planning concerns. Approximating these structures to the pit, in order to reduce the operational costs, might interfere with future pit expansions in new favorable scenarios. In such cases, impacts on project’s net present value (NPV) are inevitable and must be deal technically, evaluating several alternative scenarios to delineate a strategy to maximize profitability. The aim of this study is to evaluate, through NPV comparisons considering different scenarios with multiple constraints, under geological uncertainty, the possibility of moving waste piles and infrastructure buildings from their current position and/or defining priorities to after measuring the impact that each constraint represents on the project´s profitability. The methodology will be applied to a phosphate mine, to determine the best alternative from a long-term mine planning perspective. Using the hybrid pits method, applied to a simulated grades model, allowed the identification os occurrence probability zones within mathematical pit, providing critical data to support decision making regarding infrastructure relocation.

Gli stili APA, Harvard, Vancouver, ISO e altri

43

Brooks, Mark Whitfield 1964. "Distribution and assessment of expansive clay soils in the Tucson Basin, Arizona". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/276976.

Testo completo

Abstract (sommario):

Expansive soils contain clay minerals that undergo a change in bulk volume in response to variances in environmental conditions. The ability to predict the occurrence and geotechnical behavior of swelling soils with a known degree of certitude would allow engineers to take measures to limit the damage resulting from these metastable soils. Research was conducted to investigate the regional distribution, mineralogy, and engineering properties of expansive soils in the Tucson Basin. Mineralogic studies employed X-ray diffraction procedures for the identification of clay mineralogy. The compilation of expansion-related soil parameters, from the geotechnical job-files of a local engineering consulting firm, allowed the development of an engineering database. The application of geostatistical analysis for the cartographical representation of mineralogic and geotechnical data permitted a regional characterization of expansive clay soils. Clay mineralogy was found to be directly related to the volumetric stability displayed by native soils, as well as the geology of the Tucson Basin.

Gli stili APA, Harvard, Vancouver, ISO e altri

44

Wu, Xingyi. "Three-Dimensional Finite Element Analysis of the Pile Foundation Behavior in Unsaturated Expansive Soil". Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42028.

Testo completo

Abstract (sommario):

Expansive soils, which are widely referred to as problematic soils are extensively found in many countries of the world, especially in semi-arid and arid regions. Several billions of dollars are spent annually for maintenance or for repairs to the structures constructed with and within expansive soils. The major problems of expansive soils can be attributed to the volume changes associated with the alternate wetting and drying conditions due to the influence of environmental factors. Pile foundations have been widely accepted by practicing engineers as a reasonably good solution to reduce the damages to the structures constructed on expansive soils. Typically, piles foundations are extended through the active layer of expansive soil to reach the bedrock or placed on a soil-bearing stratum of good quality. Such a design and construction approach typically facilitates pile foundations to safely carry the loads from the superstructures and reduce the settlement. However, in many scenarios, damages associated with the pile foundations are due to the expansion of the soil that is predominantly in the active zone that contributes to the pile uplift. Such a behavior can be attributed to the water infiltration into the expansive soil, which is a key factor that is associated with the soil swelling. Due to this phenomenon, expansive soil typically moves upward with respect to the pile. This generates extra positive friction on the pile because of the relative deformation. If the superstructure is light or the applied normal stress on the head of the piles is not significant, it is likely that there will be an uplift of the pile contributing to the damage of the superstructure. In conventional engineering practice, the traditional design methods that include the rigid pile method and the elastic pile method are the most acceptable in pile foundation design. These methods are typically based on a computational technique that uses simplified assumptions with respect to soil and water content profile and the stiffness and shear strength properties. In other words, the traditional design method has limitations, as they do not take account of the complex hydromechanical behavior of the in-situ expansive soils. With the recent developments, it is possible to alleviate these limitations by using numerical modeling techniques such as finite element methods. In this thesis, a three-dimensional finite element method was used to study the hydro-mechanical behavior of a single pile in expansive soils during the infiltration process. In this thesis, a coupled hydro-mechanical model for the unsaturated expansive soil is implemented into Abaqus software for analysis of the behavior of single piles in expansive soils during water infiltration. A rigorous continuum mechanics based approach in terms of two independent stress state variables; namely, net normal stress and suction are used to form two three-dimensional constitutive surfaces for describing the changes in the void ratio and water content of unsaturated expansive soils. The elasticity parameters for soil structure and water content in unsaturated soil were obtained by differentiating the mathematical equations of constitutive surfaces. The seepage and stress-deformation of expansive soil are described by the coupled hydro-mechanical model and the Darcy’s law. To develop the subroutines, the coupled hydro-mechanical model is transferred into the coupled thermal-mechanical model. Five user-material subroutines are used in this program. The user-defined field subroutine (USDFILD) in Abaqus is used to change and transfer parameters. Three subroutines including user-defined material subroutine (UMAT), user-defined thermal material subroutine (UMATHT), and user-defined thermal expansion subroutine (UEXPAN) are developed and used to calculate the stress-deformation, the hydraulic behavior, and the expansion strain, respectively. Except for the coupled hydro-mechanical model of unsaturated expansive soils, a soil-structure interface model is implemented into the user-defined friction behavior subroutine (FRIC) to calculate the friction between soil and pile. The program is verified by using an experimental study on a single pile in Regina clay. The results show that for the single pile in expansive soil under a vertical load, water infiltration can cause a reduction in the pile shaft friction. More pile head load is transferred to the pile at greater depth, which increases the pile head settlement and pile base resistance. In future, the proposed method can also be extended for verification of other case studies from the literature. In addition, complex scenarios can be investigated to understand the behavior of piles in expansive soils.

Gli stili APA, Harvard, Vancouver, ISO e altri

45

Yesilbas, Gulsah. "Stabilization Of Expansive Soils By Using Aggregate Waste, Rock Powder And Lime". Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604950/index.pdf.

Testo completo

Abstract (sommario):

Expansive soils are a worldwide problem that poses several challenges for civil engineers. Such soils swell when given an access to water and shrink when they dry out. The most common and economical method for stabilizing these soils is using admixtures that prevent volume changes. In this study the effect of using rock powder and aggregate waste with lime in reducing the swelling potential is examined. The expansive soil used in this study is prepared in the laboratory by mixturing kaolinite and bentonite. Lime was added to the soil at 0 to 9 percent by weight. Aggregate waste and rock powder were added to the soil at 0 to 25 percent by weight. Grain size distribution, Atterberg limits and swell percent and rate of swell of the mixtures were determined. Specimens were cured for 7 and 28 days. This method of treatment caused a reduction in the swelling potential and the reduction was increased with increasing percent stabilizers.

Gli stili APA, Harvard, Vancouver, ISO e altri

46

Muchelo, Ronald Omeli. "Urban expansion and loss of prime agricultural land in Sub-Saharan Africa: a challenge to soil conservation and food security". Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/18116.

Testo completo

Abstract (sommario):

Urbanisation often involves the conversion of various land use and land cover (LULC) classes including agricultural land to urban uses and leads to loss of soil diversity. Unfortunately, there is limited literature on soils lost in Sub-Saharan African (SSA) cities due to lack of detailed soil information yet this region is the fastest growing globally. This study attempts to bridge this gap by using remote sensing data and digital soil mapping (DSM) techniques to assess the rate of agricultural land conversion, determine the appropriate pre-urban soil prediction model and estimate the extent of loss of soils diversity and urban and peri-urban agriculture (UPA) using urban centres in Uganda as case studies. Multi-temporal LULC classification of Landsat ETM+ and TM images showed that built-up area in Kampala expanded 8 times between 1989 and 2015 and 5 times in Mbarara between 2002 and 2016 as a result of the conversion of savannah, wetlands and systematic targeting of agricultural land. DSM techniques involving legacy soil data and soil observations were used to predict the pre-urban soil patterns by modelling the relationships between observed soil classes and environmental covariates using random forests (RF), Multinomial Logistic Regression (MLR) and Boosted Regression Trees (BT) algorithms. The overall prediction accuracy was over 70% producing soil maps at 30m resolution. The soil diversity loss was determined by overlaying RF soil map with the multi-temporal LULC maps. The results show that 74% of the soils lost were in high and medium quality class for agricultural production. Moreover, the average size of farms under UPA decreased from about 1.9 acres in 2002 to about 0.5 acres in 2015. This study has revealed that DSM techniques and remote sensing can be useful in quantifying the loss of soil diversity to urbanisation and provides quantitative evidence that rapid urbanisation could lead to loss of good soils and increase food insecurity in SSA cities.

Gli stili APA, Harvard, Vancouver, ISO e altri

47

Wayllace, Alexandra Likos William J. "Volume change and swelling pressure of expansive clay in the crystalline swelling regime". Diss., Columbia, Mo. : University of Missouri--Columbia, 2008. http://hdl.handle.net/10355/7110.

Testo completo

Abstract (sommario):

Title from PDF of title page (University of Missouri--Columbia, viewed on March 2, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dr. William Likos, Thesis Supervisor. Vita. Includes bibliographical references.

Gli stili APA, Harvard, Vancouver, ISO e altri

48

Teston, Felipe. "Instabilidade gravitacional para um universo estático e em expansão sob influência de termos dissipativos". reponame:Repositório Institucional da UFPR, 2017. http://hdl.handle.net/1884/49566.

Testo completo

Abstract (sommario):

Orientador: Prof. Dr. Gilberto Medeiros Kremer
Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Física. Defesa: Curitiba, 22/02/2017
Inclui referências : f. 72-74
Resumo: Com o início da fase da recombinação e por consequência o desacoplamento dos fótons da matéria, as primeiras estruturas passaram a ser formadas no Universo. A Cosmologia tenta, desde os séculos passados, determinar relações matemáticas que descrevem o crescimento destas estruturas para pequenas e grandes escalas. Jeans inaugurou o estudo da formação de estruturas em 1902 levando em conta a geração de atuações e a evolução dos modos perturbados para diferentes eras do Universo. Com seu trabalho, Jeans introduziu uma constante que hoje _e conhecida como comprimento de Jeans que descreve a condição mínima, em termos de comprimento de onda, para que uma estrutura cósmica seja formada. Neste trabalho iremos fazer uso das equações de uido da Cosmologia Newtoniana para estudar pequenas utuações de densidade e temperatura em um Universo estático e em expansão.
Abstract: After the decoupling of photons from matter, the process of structure formation was ignited, giving origin to the large scale structure of the Universe as is known today. One of the main goal of the XIX century cosmology was to establish a fundamental framework to describe the growth of small ripples and the mechanism behind the generation of such structures within small and large cosmological scales. The seminal work of Jeans in 1902 gave the _rst approach to deal with structures formation process by taking into account the physical origin of small uctuation, along with the evolution of the perturbed modes during di_erent kinds of cosmological eras. In the aforesaid work, Jeans introduced a characteristic scale, known as Jeans scale, which indicates the minimal condition which assures the formation of cosmic structures. In the present thesis, we are going to make use of such formalism within the context of Newtonian cosmology with a cosmic uid as the main source. Our aim is to examine the small uctuations of matter density along with small uctuation of temperature for a static universe and for an expanding universe.

Gli stili APA, Harvard, Vancouver, ISO e altri

49

Sanfelici, Daniel de Mello. "A metrópole sob o ritmo das finanças: implicações socioespaciais da expansão imobiliária no Brasil". Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/8/8136/tde-07012014-093205/.

Testo completo

Abstract (sommario):

No último decênio, as metrópoles brasileiras foram profundamente reconfiguradas pela proliferação de projetos imobiliários de grande porte. O investimento imobiliário, antes fortemente centralizado nas áreas mais valorizadas das metrópoles, irradiou-se também para as periferias e franjas metropolitanas, com importantes repercussões socioespaciais. Esta pesquisa procurou fornecer algumas explicações para esse fenômeno, colocando em foco a crescente penetração das finanças na produção do espaço urbano no Brasil. Desde meados da década de 1990, sucessivos governos, estimulados por organizações privadas ligadas ao setor financeiro, empenharam-se na criação de marcos regulatórios e institucionais favoráveis à circulação do capital financeiro pelo ambiente construído urbano. Esse novo ambiente institucional foi uma peça importante não apenas na ampliação do financiamento habitacional no transcurso da década de 2000, mas também na aproximação do investimento imobiliário com a dinâmica do mercado de capitais. Esta integração entre mercado de capitais e mercado imobiliário ganhou força, primordialmente, com a abertura de capital das principais incorporadoras imobiliárias, ocorrida entre 2005 e 2007, quando grandes fundos de investimento adquiriram participação nessas empresas. Com base em entrevistas, coleta de dados secundários e publicações setoriais, procurou-se, nessa tese, elucidar algumas das implicações desse entrelaçamento das incorporadoras imobiliárias com o mercado de capitais. Observou-se uma profunda mudança nas estratégias empresariais após a emissão de ações e debêntures, o que se explica, em grande medida, pelas exigências de rentabilidade colocadas pelos novos acionistas. A maior parte das empresas adotou políticas agressivas de expansão tanto na escala da metrópole quanto na escala do território, multiplicando seus volumes de lançamentos entre 2005 e 2010. Também ocorreu um aperfeiçoamento das formas de captura de rendas urbanas. Uma análise da atuação dessas incorporadoras no mercado imobiliário de Porto Alegre indicou, além disso, que esse refinamento das estratégias de investimento produziu, de uma parte, uma exacerbação das formas de segregação e fragmentação socioespacial urbana e, de outra, um rearranjo escalar do processo de urbanização. Configura-se, portanto, uma situação em que as metrópoles brasileiras são crescentemente transformadas segundo as determinações e os ritmos ditados pelas finanças, que se beneficiam dos rendimentos produzidos pela reestruturação socioespacial.
Over the past decade, Brazilian cities were thorougly reconfigured by a profusion of large-scale real estate developments. Previously restricted to high-end neighborhoods, real estate investment has expanded to include peripheral and outlying areas of major metropolitan areas, thus producing dramatic socio-spatial effects. The present research provides an explanation for this phenomenon by focusing on the growing penetration of finance into the production of urban space in Brazil. Since the mid-1990s, successive governments, encouraged by private organizations tied to the financial sector, have made an effort to create a regulatory and institutional framework favorable to the circulation of capital in the built environment. This new institutional atmosphere was a key element not only in the growth of mortgage lending in the 2000s, but also in the convergence of real estate investment and the dynamics of capital markets. The integration of capital markets and real estate markets occurred primarily through the initial public offering of large developers between 2005 and 2007, when huge investment funds acquired participation in these firms. Based on interviews, collected data and sectoral publications, this dissertation has attempted to clarify some of the consequences of the links that were forged between developers and capital markets. We observed a profound change in developers strategies after their IPOs, mostly explained by the high yields demanded by investors. Most developers adopted a highly aggressive policy of expansion, both on the scale of the city and on the scale of the territory, multiplying their output between 2005 and 2010. The ways in which urban land rents were extracted had also improved. Our analysis of how these developers have operated in Porto Alegre (southern Brazil) indicates, moreover, that developers finely honed business strategies have, on the one hand, intensified socio-spatial segregation and fragmentation, while on the other, have been responsible for a rescaling of the urbanization process. The outcome is a situation in which metropolitan areas are, to an incresing degree, transformed according the determinations and rhythms dictated by finance capital, which benefits from the returns generated by socio-spatial restructuring.

Gli stili APA, Harvard, Vancouver, ISO e altri

50

Silva, Daniel Martins [UNESP]. "A expansão para o Oeste: a Parceria Transpacífica sob a perspectiva dos Estados Unidos". Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/139472.

Testo completo

Abstract (sommario):

Submitted by DANIEL MARTINS SILVA null (daniel_m105@hotmail.com) on 2016-06-13T12:09:12Z No. of bitstreams: 1 Dissertação-Final-2016.pdf: 1232731 bytes, checksum: a3b1a459a153bdc0df5be33dcfc2b83a (MD5)
Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-06-15T19:30:27Z (GMT) No. of bitstreams: 1 silva_dm_me_mar.pdf: 1232731 bytes, checksum: a3b1a459a153bdc0df5be33dcfc2b83a (MD5)
Made available in DSpace on 2016-06-15T19:30:27Z (GMT). No. of bitstreams: 1 silva_dm_me_mar.pdf: 1232731 bytes, checksum: a3b1a459a153bdc0df5be33dcfc2b83a (MD5) Previous issue date: 2016-05-17
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Entre o fim do governo George W. Bush e o primeiro mandato do governo Barack Obama os Estados Unidos iniciou sua participação na Parceria Transpacífica (PTP). A fim de entender as motivações norte-americanas para este acordo regional de comércio, a dissertação trabalhou com a hipótese de que a evolução do novo regionalismo asiático, a partir dos anos 2000, teve um peso significativo na estratégia estadunidense de comércio. Destacam-se a ASEAN+3 e a ASEAN+6, grupos liderados pelo Japão e China para incrementar a integração econômica do Leste Asiático. Diante da emergência desta configuração, os Estados Unidos estiveram excluídos do processo. Para averiguar esta afirmação utilizamos a plataforma Inside Trade, entrevistas e notícias de jornais relevantes; arquivos da Casa Branca (relatórios dos principais órgãos decisórios e discursos); relatórios anuais e outros documentos do USTR; além de arquivos do Departamento de Estado (em especial do Escritório de Assuntos do Leste Asiático e Pacífico). A análise do material empírico revelou que o receio de exclusão dos Estados Unidos e da predominância da China como ator político no comércio intra-asiático foram questões frequentemente levantadas pelo empresariado e policy-makers da política comercial norte-americana. Além de circunstâncias regionais, o envolvimento dos Estados Unidos no acordo se explica pelo seu interesse em moldar as regras que conformam o regime global de comércio. Demonstramos que expandir a presença política do país na Ásia-Pacífico e constranger a emergência chinesa eram tarefas fundamentais para alcançar este objetivo.
Between the end of George W. Bush’s government and Barack Obama’s first term, the United States began its participation in Transpacific Partnership (TPP). In order to understand american motivation for this regional trade agreement, our hypothesis supported that new asian regionalism dynamics had a weight in US trade policy strategy. We highlitgh ASEAN+3 and ASEAN+6, groups leading for Japan and China to increase economic integration of East Asia. In this configuration, the United States had been excluded. Aiming to check this, we use the “Inside Trade” platform, interviews and news of important newspapers; the White House archives (reports of the main agencies and discourses); annual reports and other documents from USTR; also US Department of State’s archives (especially the Bureau of East Asian and Pacific Affairs). The empirical analysis reveal that fear of United States’ exclusion and the China’s predominance as political actor in intra-asian trade were often raised by business and policy makers of US trade policy. Beyond regional reasons, US envolvement is explained by its interest to shape the rules conforming global trade regime. We demonstrate that raising US political presence and constraining chinese emergence were fundamental tasks to achieve this goal.

Gli stili APA, Harvard, Vancouver, ISO e altri

Tesi sul tema "Expansion de soi"

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili