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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Thermal structure and geodynamics of subduction zones

Wada, Ikuko 21 August 2009 (has links)
The thermal structure of subduction zones depends on the age-controlled thermal state of the subducting slab and mantle wedge flow. Observations indicate that the shallow part of the forearc mantle wedge is stagnant and the slab-mantle interface is weakened. In this dissertation, the role of the interface strength in controlling mantle wedge flow, thermal structure, and a wide range of subduction zone processes is investigated through two-dimensional finite-element modelling and a global synthesis of geological and geophysical observations. The model reveals that the strong temperature-dependence of the mantle strength always results in full slab-mantle decoupling along the weakened part of the interface and hence complete stagnation of the overlying mantle. The interface immediately downdip of the zone of decoupling is fully coupled, and the overlying mantle is driven to flow at a rate compatible with the subduction rate. The sharpness of the transition from decoupling to coupling depends on the rheology assumed and increases with the nonlinearity of the flow system. This bimodal behaviour of the wedge flow gives rise to a strong thermal contrast between the cold stagnant and hot flowing parts of the mantle wedge. The maximum depth of decoupling (MDD) thus dictates the thermal regime of the forearc. Observed surface heat flow patterns and petrologically and geochemically estimated mantle wedge temperatures beneath the volcanic arc require an MDD of 70-80 km in most, if not all, subduction zones regardless of their thermal regime of the slab. The common MDD of 70-80 km explains the observed systematic variations of the petrologic, seismological, and volcanic processes with the thermal state of the slab and thus explains the rich diversity of subduction zones in a unified fashion. Models for warm-slab subduction zones such as Cascadia and Nankai predict shallow dehydration of the slab beneath the cold stagnant part of the mantle wedge, which provides ample fluid for mantle wedge serpentinization in the forearc but little fluid for melt generation beneath the arc. In contrast, models for colder-slab subduction zones such as NE Japan and Kamchatka predict deeper dehydration, which provides greater fluid supply for melt generation beneath the arc and allows deeper occurrence of intraslab earthquakes but less fluid for forearc mantle wedge serpentinization. The common MDD also explains the intriguing uniform configuration of subduction zones, that is, the volcanic arc always tends to be situated where the slab is at about 100 km depth. The sudden onset of mantle wedge flow downdip of the common MDD overshadows the thermal effect of the slab, and the resultant thermal field and slab dehydration control the location of the volcanic arc. The recognition of the fundamental importance of the MDD has important implications to the study of geodynamics and earthquake hazard in subduction zones.
72

Avaliação do efeito térmico das soleiras de diabásio nas rochas geradoras da formação Irati (Bacia do Paraná, Brasil) através de técnicas de modelagem numérica / Assessment of the thermal effects of diabase sills on source rocks of Irati formation (Parana, Basin, Brazil) using numerical modeling techniques

Luís Maurício Salgado Alves Corrêa 28 February 2006 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Na avaliação da maturidade de horizontes geradores e da história térmica de uma bacia com registro de atividade magmática é preciso considerar o efeito térmico imposto pela intrusão de corpos ígneos, como diques e soleiras. Dessa maneira, foi realizada a análise numérica transiente, pelo método de diferenças finitas, do fluxo térmico por condução provocado pela intrusão das soleiras básicas cretáceas nos horizontes geradores do Membro Assistência, Formação Irati, Bacia do Paraná. Esta análise, por sua vez, viabilizou a modelagem do parâmetro de reflectância da vitrinita nos estratos de folhelhos adjacentes às soleiras. Para tanto, foram utilizados os dados de seção de três poços, os quais registram espessuras de soleiras de até 4 m, e um poço com uma soleira de 27 m de espessura. Os poços localizam-se na porção sudeste da bacia. Na simulação numérica, foi considerado o processo de solidificação do magma ou de cristalização das suas fases minerais. A modelagem de reflectância da vitrinita baseou-se em um modelo pré-concebido da história térmica da Formação Irati, sendo os resultados desta simulação de maturidade do querogênio obtidos através do uso do programa EASY%Ro. Considerando-se os erros embutidos no modelo numérico e na discretização da história térmica dos estratos estudados, foram obtidos valores modelados de reflectância da vitrinita similares aos valores medidos nos poços pelo método tradicional. Somente no caso da seção com a soleira de 27 m de espessura houve uma grande diferença entre estes valores. Contudo, o alto coeficiente de correlação (0,95) entre estes possibilita a correção do efeito da espessura da soleira em análises futuras. Assim, a análise numérica simulou o halo térmico da soleira, caracterizado, segundo os dados de modelagem de refletância da vitrinita, por uma faixa acima e abaixo da soleira com espessura equivalente à espessura da soleira encaixada nos estratos geradores da Formação Irati. Essa metodologia de avaliação propicia um estudo preditivo das condições de maturidade de horizontes geradores em bacias ou áreas com magmatismo intrusivo, nas quais as análises do parâmetro de reflectância da vitrinita sejam ausentes ou escassas. / To evaluate the thermal maturity and thermal history of source rocks in basins with magmatic activity it is important to consider the thermal effects imposed by igneous intrusions, such as sills and dykes. This work uses the finite difference method for such evaluation, with the transient numerical analysis of heat conduction from Cretaceous diabase sills intruded into the source rocks of the Assistência Member, Irati Formation, Paraná Basin. This analysis has permitted modeling vitrinite reflectance of the shale strata adjacent to the sills. The data of four wells are used from the southeastern portion of the basin, with diabase thicknesses, respectively, of 1m, 2 m, 4 m and 27 m. The numerical simulation includes the process of magma solidification or mineral phase crystallization. The vitrinite reflectance modeling followed a pre-established thermal history of the Irati Formation, using the EASY%Ro program to simulate kerogen maturity levels. Considering the errors built into the numerical model and the thermal history discretisation of studied strata, the acquired values of modeled vitrinite reflectance closely resembled well data analyzed by the traditional method. Major discrepancies were observed in the case of the well containing a sill 27 m thick, but even in this case the high correlation coefficient (0,95) between the measured and calculated values is expected to permit correction of the sill thickness effect in future studies. The numerical analysis correctly simulated the thermal halo induced by sill emplacement, enabling vitrinite reflectance modeling to characterize it as a zone extending both above and below the sill with thicknesses similar to that of the sills. This evaluation methodology contributes to a predictive study of the maturity conditions of source rocks within basins or areas with intrusive magmatism where analysis of the vitrinite reflectance parameter are sporadic or absent.
73

Refrigeração evaporativa por aspersão em telhas de fibrocimento: estudo teórico e experimental

Roriz, Victor Figueiredo 01 August 2007 (has links)
Made available in DSpace on 2016-06-02T20:09:08Z (GMT). No. of bitstreams: 1 1646.pdf: 3878244 bytes, checksum: 1b913364f7458c2e95fc16bda01f835e (MD5) Previous issue date: 2007-08-01 / Financiadora de Estudos e Projetos / This research focuses the evaporative cooling by water aspersion on wavy cement fiber tiles in the city of São Carlos, SP, seeking to use it to reduce the buildings heat gains. A theoretical model was developed, based on classic equations of fluids mechanic, applied to iterative calculations of heat flows on the tile superior surface, considered as control surface. In the work development, this model was progressively adjusted to experimental data obtained in a test cell, exposed to the local climatic conditions, with the monitoring of superficial temperatures of both faces in two tiles, one maintained dry and other under intermittent aspersion of water. The research results indicated that, despite of still being susceptible to improvement, the theoretical model already presents quite satisfactory approach with the measured data. Applying a statistical adjustment to the proposed model of iterative heat flows calculation, it was obtained a correlation coefficient between measured and estimated temperatures of 0,999 and a standard deviation of 0,35 ºC. During the experiments, the average evaporative heat flow was 409 W/m2. Theaverage water volume evaporated was 0,7 l/(m².h), corresponding to an average difference of temperatures among the compared tiles of 5,12 K, for the daylight period. Due to the growing need of energy consumption reduction, this procedure seems to be a good option to reduce buildings thermal load, if compared to conventional air conditioning systems / Esta pesquisa enfoca a refrigeração evaporativa por aspersão de água sobre telhas onduladas de fibrocimento, na cidade de São Carlos, SP, visando sua utilização para redução dos ganhos de calor em edificações. Um modelo teórico foi desenvolvido, baseado em equações clássicas da mecânica dos fluidos, aplicadas em cálculos iterativos dos fluxos de calor sobre a superfície superior da telha, considerada como superfície de controle. No desenvolvimento do trabalho, este modelo foi progressivamente ajustado a dados experimentais obtidos em uma célula de teste, exposta às condições climáticas locais, sendo monitoradas temperaturas superficiais de ambas as faces em duas telhas, uma mantida seca e outra sob aspersão intermitente de água. Os resultados da pesquisa indicaram que, apesar de ainda ser passível de aprimoramento, o modelo teórico já apresenta aproximação bastante satisfatória com os dados medidos. Aplicando-se um ajuste estatístico ao modelo proposto de cálculo iterativo dos fluxos de calor, obteve-se um coeficiente de correlação entre temperaturas medidas e estimadas de 0,999 e um desvio padrão de 0,35 ºC. Durante os experimentos, o fluxo médio de calor por evaporação foi de 409 W/m2. O volume médio de água evaporado foi de 0,7 l/(m².h), correspondendo a uma diferença média de temperaturas entre as telhas comparadas, para o período diurno, de 5,12 K. Frente à crescente necessidade de redução de consumo de energia, esta parece uma boa opção para redução da carga térmica dos edifícios, se comparada aos sistemas convencionais de condicionamento de ar
74

Avaliação do efeito térmico das soleiras de diabásio nas rochas geradoras da formação Irati (Bacia do Paraná, Brasil) através de técnicas de modelagem numérica / Assessment of the thermal effects of diabase sills on source rocks of Irati formation (Parana, Basin, Brazil) using numerical modeling techniques

Luís Maurício Salgado Alves Corrêa 28 February 2006 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Na avaliação da maturidade de horizontes geradores e da história térmica de uma bacia com registro de atividade magmática é preciso considerar o efeito térmico imposto pela intrusão de corpos ígneos, como diques e soleiras. Dessa maneira, foi realizada a análise numérica transiente, pelo método de diferenças finitas, do fluxo térmico por condução provocado pela intrusão das soleiras básicas cretáceas nos horizontes geradores do Membro Assistência, Formação Irati, Bacia do Paraná. Esta análise, por sua vez, viabilizou a modelagem do parâmetro de reflectância da vitrinita nos estratos de folhelhos adjacentes às soleiras. Para tanto, foram utilizados os dados de seção de três poços, os quais registram espessuras de soleiras de até 4 m, e um poço com uma soleira de 27 m de espessura. Os poços localizam-se na porção sudeste da bacia. Na simulação numérica, foi considerado o processo de solidificação do magma ou de cristalização das suas fases minerais. A modelagem de reflectância da vitrinita baseou-se em um modelo pré-concebido da história térmica da Formação Irati, sendo os resultados desta simulação de maturidade do querogênio obtidos através do uso do programa EASY%Ro. Considerando-se os erros embutidos no modelo numérico e na discretização da história térmica dos estratos estudados, foram obtidos valores modelados de reflectância da vitrinita similares aos valores medidos nos poços pelo método tradicional. Somente no caso da seção com a soleira de 27 m de espessura houve uma grande diferença entre estes valores. Contudo, o alto coeficiente de correlação (0,95) entre estes possibilita a correção do efeito da espessura da soleira em análises futuras. Assim, a análise numérica simulou o halo térmico da soleira, caracterizado, segundo os dados de modelagem de refletância da vitrinita, por uma faixa acima e abaixo da soleira com espessura equivalente à espessura da soleira encaixada nos estratos geradores da Formação Irati. Essa metodologia de avaliação propicia um estudo preditivo das condições de maturidade de horizontes geradores em bacias ou áreas com magmatismo intrusivo, nas quais as análises do parâmetro de reflectância da vitrinita sejam ausentes ou escassas. / To evaluate the thermal maturity and thermal history of source rocks in basins with magmatic activity it is important to consider the thermal effects imposed by igneous intrusions, such as sills and dykes. This work uses the finite difference method for such evaluation, with the transient numerical analysis of heat conduction from Cretaceous diabase sills intruded into the source rocks of the Assistência Member, Irati Formation, Paraná Basin. This analysis has permitted modeling vitrinite reflectance of the shale strata adjacent to the sills. The data of four wells are used from the southeastern portion of the basin, with diabase thicknesses, respectively, of 1m, 2 m, 4 m and 27 m. The numerical simulation includes the process of magma solidification or mineral phase crystallization. The vitrinite reflectance modeling followed a pre-established thermal history of the Irati Formation, using the EASY%Ro program to simulate kerogen maturity levels. Considering the errors built into the numerical model and the thermal history discretisation of studied strata, the acquired values of modeled vitrinite reflectance closely resembled well data analyzed by the traditional method. Major discrepancies were observed in the case of the well containing a sill 27 m thick, but even in this case the high correlation coefficient (0,95) between the measured and calculated values is expected to permit correction of the sill thickness effect in future studies. The numerical analysis correctly simulated the thermal halo induced by sill emplacement, enabling vitrinite reflectance modeling to characterize it as a zone extending both above and below the sill with thicknesses similar to that of the sills. This evaluation methodology contributes to a predictive study of the maturity conditions of source rocks within basins or areas with intrusive magmatism where analysis of the vitrinite reflectance parameter are sporadic or absent.
75

Analise da solidificação sob fluxo de calor radial cilindrico / Analysis of the solidification uner radial heat flow

Eid, Marco Antonio 22 July 2007 (has links)
Orientador: Rezende Gomes dos Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-09T22:01:50Z (GMT). No. of bitstreams: 1 Eid_MarcoAntonio_M.pdf: 19245694 bytes, checksum: b272ecb88a2fa2a6affcf2a60d7e8d47 (MD5) Previous issue date: 2007 / Resumo: Apesar da importância tecnológica da solidificação de ligas metálicas sob fluxo de calor radial, relativamente poucos estudos estão sendo feitos nessa área. Neste trabalho, a solidificação da liga Al 4,5%Cu em molde de aço radial cilíndrico é analisada e comparada com a solidificação direcional em molde resfriado.Inicialmente a variação de temperatura em diferentes posições no metal e no molde foi medida durante a solidificação usando um sistema de aquisição de dados. Essas variações de temperatura foram introduzidas em um método numérico para determinar a variação do coeficiente de transferência de calor na interface metal/molde pelo método inverso. Os resultados para a solidificação unidirecional e radial foram comparados mostrando que o coeficiente de transferência de calor para o fluxo de calor radial é menor. A variação dos espaçamentos dendritos secundários foram medidos através de um microscópio óptico. Comparações entre os resultados mostraram maiores espaçamentos para fluxo de calor radial. Comparações entre variações e temperaturas calculadas numéricas e experimentalmente comprovaram que o método numérico descreve satisfatoriamente o processo de solidificação radial / Abstract: In spite of technological importance of solidification of metallic alloys under radial heat flow, relatively few studies have been carried out in this area. In this work the solidification of Al 4.5 wt% Cu cylinders against a steel massive mold is analyzed and compared with unidirectional solidification against a cooled mold. Initially temperature variations at different positions in the casting and in the mold were measured during solidification using a data acquisition system. These temperature variations were introduced in a numerical method in order to determine the variation of heat transfer coefficient at metal/mold interface by inverse method. The results for unidirectional and radial solidification were compared showing that the heat transfer coefficient is smaller for radial heat flux. The primary and secondary dendrite arm spacing variations were measured through optical microscopy. Experimental results for temperature variations were applied to estimate thermal parameters of the solidification process. Comparisons carried out between experimental and numerical data showed that the numerical method describes well the solidification processes under radial heat flux / Mestrado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica
76

Experimental investigation of thermal and fluid dynamical behavior of flows in open-ended channels : Application to Building Integrated Photovoltaic (BiPV) Systems / Etude expérimentale du comportement dynamique thermique et fluide des flux dans les canaux ouverts : Application à la création de systèmes photovoltaïques intégrés au bâti (BIPV)

Sanvicente, Estibaliz 03 July 2013 (has links)
Face à la problématique énergétique, les solutions envisagées dans le domaine du bâtiment s’orientent sur un mix énergétique favorisant la production locale ainsi que l’autoconsommation. Concernant l’électricité, les systèmes photovoltaïques intégrés au bâtiment (BiPV) représentent l’une des rares technologies capables de produire de l’électricité localement et sans émettre de gaz à effet de serre. Cependant, le niveau de température auquel fonctionnent ces composants, influence sensiblement leur efficacité ainsi que leur durée de vie. Ces deux constats mettent en lumière l’importance du refroidissement passif par convection naturelle de ces modules. La configuration privilégiée est une configuration d’intégration au sein d’une enveloppe ventilée qualifiée de double-peau photovoltaïque. La présente étude expérimentale porte sur les transferts de chaleur et les caractéristiques de l’écoulement en convection naturelle dans des canaux chauffés verticaux ou inclinés. Deux bancs d’essais existants ont été complétés afin d’obtenir des données. Ils sont composés de deux plaques planes parallèles séparées par une lame d’air. Les parois sont soumises à des conditions aux limites de type densité de flux imposée. Les températures moyennes à la paroi ont été mesurées par thermocouples. Un système de vélocimétrie par image de particules a permis d’obtenir des profils de vitesse moyenne ainsi que les distributions d’intensité turbulente dans l’écoulement. Les champs de vitesse instantanée ont également été examinés. Trois configurations ont été étudiées avec un nombre de Rayleigh variant entre 3,86 x 105 et 6,22 x 106. La première est un canal vertical avec une des deux parois chauffée uniformément. La seconde est un canal vertical dans lequel les deux parois sont chauffées de façon non-uniforme et alternée. La troisième est de type canal incliné chauffé uniformément sur la paroi supérieure. Le rapport de forme du canal (largeur/hauteur) est de 1/15 pour le deux premières configurations et de 1/16 pour la troisième. Une attention particulière a été portée sur l’identification de la zone de transition laminaire-turbulent. L’étude a permis de mettre en évidence la sensibilité de l’écoulement aux perturbations extérieures. Pour un chauffage uniforme et asymétrique, à partir d’un nombre de Rayleigh Ra* de 3.5 x 106 et pour θ = 60° et 90°, il a été constaté que la propagation de structures cohérentes dans le canal a lieu à partir de la mi-hauteur de ce canal. Ces instabilités favorisent alors les transferts thermiques. Dans le cas d’un chauffage non-uniforme sur les deux parois du canal, l’écoulement est fortement perturbé ce qui conduit à l’augmentation du brassage et de la contrainte de Reynolds sur la majorité de la largeur du canal. Enfin, pour chacune des configurations, des corrélations permettant de quantifier les transferts de chaleur à la paroi et au sein de la lame d’air (nombre de Nusselt moyen en fonction du nombre de Rayleigh) ont été établies. / Among technologies capable to produce electricity locally without contributing to GHG releases, building integrated PV systems (BIPV) could be major contributor. However, when exposed to intense solar radiation, the temperature of PV modules increase significantly, leading to a reduction in efficiency so that only about 14% of the incident radiation is converted into electrical energy. The high temperature also decrease the life of the modules, thereby making passive cooling of the PV components through natural convection a desirable and cost-effective means of overcoming both difficulties. An experimental investigation of heat transfer and fluid flow characteristics of natural convection of air in vertical and inclined open-ended heated channels is therefore undertaken so as provide reliable information for the design of BIPV. Two experimental set ups were developed and used during the present investigations; one located at the CETHIL laboratory in Lyon, the F-device and the other located at the University of New South Wales in Sydney, the R-device. Both channels consisted of two wide parallel plates each of which could be subjected to controlled uniform or non-uniform heat fluxes. The investigation has been conducted by analyzing the mean wall temperatures, measured by thermocouples and mean velocity profiles and turbulent quantity distributions of the flow, measured with a PIV system. Flow patterns close to the heated faces were also investigated. The study is particularly focused on the transition region from laminar to turbulent flow. Three different heating geometric arrangements are examined in the modified Rayleigh number range from 3.86 x 105 to 6.22 x 106. The first is a vertical channel with one wall uniformly heated while the other was unheated, the second was a vertical channel in which both walls were non-uniformly heated and the third is an inclined channel uniformly heated from above. In the vertical configurations the width-to-height channel aspect ratio was fixed at 1:15 and in the inclined ones at 1:16. It is shown that the flow is very sensitivity to disturbances emanating from the ambient conditions. Moreover, the propagation of vortical structures and unsteadiness in the flow channel which are necessary to enhance heat transfer, occurred downstream of the mid-channel section at Ra* = 3.5 x 106 for uniformly and asymmetrically heated channels inclined between 60° and 90° to the horizontal. Indeed, these unsteady flow phenomena appears upstream the location of the inflexion point observed in the temperature excess distribution of the heated wall. In the case of non-uniform heating on both sides of the channel, a stronger ‘disruption mechanism’ exists, which leads to enhanced mixing and increased Reynolds stresses over most of the width of the channel. Empirical correlations of average Nusselt number as a function of modified Rayleigh number were obtained for each configuration.
77

Bilan thermique et caractérisation géochimique de l'activité hydrothermale du volcan Rinjani, Lombok, Indonésie

Barbier, Benjamin 27 April 2010 (has links)
La caldera du volcan Rinjani contient un lac d’un volume de 1 km³ qui est probablement le plus grand lac volcanique au monde présentant une anomalie thermique nette. Ce lac présente une composition neutre chlorure sulfate bicarbonate inhabituelle pour les lacs volcaniques. Sa TDS (2600 mg/l) et conductivité (3500µs/cm) élevées indiquent un apport de fluides hydrothermaux très important. Enfin, son alcalinité élevée (520 mg/l), indique un apport important de dioxyde de carbone dans le lac.<p>Les sources thermales situées autour du Gunung Baru (cône volcanique situé dans la caldera) ont une composition chimique en éléments majeurs et une composition isotopique proche de celles du lac volcanique indiquant qu’elles sont essentiellement le résultat du recyclage du lac par le système hydrothermal. Les variations de compositions entre les différentes sources ont permis de montrer que leurs compositions est le résultat du mélange entre un fluide hydrothermal profond de composition neutre chlorure, dont la température a été estimée à 270°C, et d’un fluide plus superficiel riche en magnésium et en sulfate.<p>Le flux de dioxyde de carbone à la surface du lac a été estimé à l’aide de la méthode de la chambre d’accumulation et par calcul à environ 2300 t/j, ce qui représente un apport significatif de gaz. Cependant, comme le lac présente une structure polymictique, le risque d’accumulation de dioxyde de carbone en profondeur et donc d’éruption limnique peut être exclus.<p>Pour la première fois dans cette thèse, le modèle d’estimation des flux thermiques émis par les lacs volcaniques mis au point par Stevenson (1992) a été contraint par des mesures des paramètres météorologiques mesurés en continu, ce qui a permis de valider le modèle. De plus, nous avons pu montrer que l’essentiel des variations de températures des lacs volcaniques est dû à des variations météorologiques. En utilisant le flux thermique plutôt que la température, il est dès lors possible d’avoir accès à des variations de l’activité volcanique.<p>Le flux thermique estimé pour le lac du Rinjani est de 1700 MW, ce qui représente le flux le plus élevé jamais mesuré sur un lac volcanique aérien. Ce flux thermique est aussi plus élevé que le flux thermique mesuré sur des lacs de lave à 800°C. Ce paradoxe apparent s’explique par la plus grande dimension des lacs volcaniques, la capacité calorifique de l’eau quatre fois plus importante que celle du magma et la viscosité de l’eau 1 million de fois inférieure, ce qui fait de l’eau un excellent fluide caloporteur pour transporter les calories vers la surface.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished
78

Laboratory Investigations of Frost Action Mechanisms in Soils

Dagli, Deniz January 2017 (has links)
Phase change of the water in the soil skeleton under cold climate conditions (also known as frost action in soils) affects soil properties and can be responsible for serious alterations in a soil body; causing damages (due to the volumetric expansion known as frost heave) to structures on or below the ground surface such as foundations, roads, railways, retaining walls and pipelines, etc. In order to improve the current design methods for roads against frost action, the Swedish Transport Administration (Trafikverket) has initiated a research program. The main goals of the program are to revise the existing frost heave estimation methods and improve the frost susceptibility classification system for subgrade soils. Literature was reviewed to gather the details of different freezing test equipment around the world and to identify common trends and practices for laboratory freezing tests. Based on the literature review and the collaboration with the University of Oulu, Finland an experimental apparatus was assembled for studying frost action in the laboratory. A detailed description of the experimental apparatus is given. Top to down freezing of specimens (of 10cm height and diameter) can be monitored while keeping track of water intake, vertical displacements (heave) and the temperature profile within the sample. Loads can be applied at the top of the sample to study the effects of overburden. Moreover, the test setup was modified with a camera system to have the option of recording the experiments. Disturbed samples of two different soil types were tested. Experiments with fixed and varying temperature boundary conditions were conducted to assess the validity of the assumptions for the frost heave estimation methods currently in use in Sweden. To this end, a qualitative relationship between frost heave and heat extraction rates based on theoretical equations was established. It was shown that there is a significant difference between the preliminary findings of the experimental work and the current system being used in Sweden to quantify heave. Image analysis techniques were used on two experiments that were recorded by the camera system. Image recording and correlation analyses provided detailed information about frost front penetration and ice lens formation(s) under varying temperature boundary conditions. Thawing has also been regarded in further studies. Results of the image analyses were compared to readings from conventional displacement measurements during the same test. Significant agreement between the results of image analyses and displacement measurements has been found. Image analysis was shown to be a viable method in further understanding of frost heave mechanisms. Shortcomings and disadvantages of utilizing the theoretical equations as well as the image analysis techniques were discussed. Potential remedies for overcoming the drawbacks associated with each approach are suggested. The work is concluded by discussing the potential improvements, planned upgrades (addition of pore pressure transducers) and the future experiments to be conducted.
79

Reflexní tepelné izolace pro efektivní využití v nízkoenergetických stavbách / Reflective insulations for effective use in low energy buildings

Kalánek, Jiří January 2020 (has links)
The dissertation thesis is focused on thermal insulating properties of reflective insulation under boundary conditions typical for low-energy buildings. In the introductory part of this thesis the attention is focused on the heat transfer process. There is described primarily heat transfer by radiation. There is also described the reflective insulation and the methods of determination their thermal performance. The remaining part of the thesis deals with the analysis of the results obtained in experimental measurements. Measurement results are compared with the calculation model. Conclusions for technical practice including possibilities of further research are summarized in the final section.
80

On curvature conditions using Wasserstein spaces

Kell, Martin 22 July 2014 (has links)
This thesis is twofold. In the first part, a proof of the interpolation inequality along geodesics in p-Wasserstein spaces is given and a new curvature condition on abstract metric measure spaces is defined. In the second part of the thesis a proof of the identification of the q-heat equation with the gradient flow of the Renyi (3-p)-Renyi entropy functional in the p-Wasserstein space is given. For that, a further study of the q-heat flow is presented including a condition for its mass preservation.

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