Lic.-avh. Uppsala : Sveriges lantbruksuniv. / Härtill 2 uppsatser.

Thesis (M.S.)--Brigham Young University. Dept. of Civil and Environmental Engineering, 2008. / Includes bibliographical references (p. 67-71).

The triumvirate of tectonics, lithology, and climate control landscape evolution. This study quantifies how lithologic variation and climate-mediated changes in ecosystems perturb steady state processes in the unglaciated, soil-mantled Oregon Coast Range (OCR). I first demonstrate that minor grain-scale differences in rock properties in a seemingly uniform sandstone control differences in rock strength, biotic bedrock-to-soil production efficacy, and erosion rates and influence relief at the watershed scale. I then build on sedimentology, paleoecology, and isotopic-derived paleoerosion data I collected from a new 50 ka sediment archive at Little Lake, OR to explore climate controls on soil production and erosion rates 21 ka across the OCR and spanning 50 ky within a single watershed. In Chapter III, I combine a mechanistic frost weathering model with a regional Last Glacial Maximum (LGM) climate reconstruction and paleovegetation data to demonstrate that accelerated frost-driven erosion was pervasive across the OCR during the LGM. My findings provide a new framework to quantify how the late Pleistocene affects modern erosion and soil formation rates in unglaciated environments and implies that most landscapes reside in a transient state. In Chapter IV, I document climate-mediated ecosystem influence on erosion rates over 3 climatic intervals. 10Be-derived erosion rates increase 3x (from 0.6 mm/yr to 0.21 mm/yr) as the OCR transitioned from the open forest-dominated marine isotope stage (MIS) climate interval (50-26 ka) into the periglacial subalpine MIS 2 glacial interval (26-13 ka). Measured erosion rates fell by more than half as the subalpine ecosystem gave way to the modern MIS 1 closed canopy Douglas-fir forest. Coupling paleovegetation-derived climate information with core observations I model frost weathering intensity from ~ 43 ka to 21 ka and establish a correspondence with increasing frost weathering intensity and increasing 10Be-derived erosion rates. Utilizing a transient mixing depth and erosion rate model, I am able to broadly replicate measured erosion rates at Little Lake through time. My findings contradict previous work that suggests climate has only weak control on erosion rates. This dissertation includes previously published and unpublished co-authored material.

The aim was comparison of drought and frost resistence of selected varieties of Medicago sativa L. from domestic and foreign. The evaluation was performed by a series of laboratory experiments and observations in two replications in 2009 ? 2010. The results were evaluated as the most resistant varieties to frost variety from the Czech Republic and Slovakia. Namely variety Magda Litava, Tisa and Synthesis. As the least resistant varieties have been evaluated varieties from the warm coastal areas. Most resistant varieties to water deficit during vegetation varieties were evaluated Magda, Comete, Europe and Camilla. The climatic conditions of the Czech Republic would be most appropriate, according to the results observed varieties of Magda. It has high resistance to frost and has good results in drought. Other good varieties from Czech Republic are Pálava and Camilla. Of the foreign varieties would be best to use a French variety of Como, Europe and the Dutch variety of Capri. These varieties have good resistance to frost and high drought. The whole problem of drought and frost resistance of alfalfa is not yet explored, it would be appropriate, the results obtained confirmed by further research.

Orientador: Carlos Teofilo Salinas Sedano / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-27T04:21:17Z (GMT). No. of bitstreams: 1 Armengol_JanMateu_M.pdf: 6999606 bytes, checksum: e35806586b55eb3f8f1b370625009ba8 (MD5) Previous issue date: 2015 / Resumo: Neste trabalho é apresentado um modelo para a formação de gelo poroso entre placas planas paralelas baseado em um novo tratamento bidimensional da taxa de crescimento. O modelo considera as equações de transporte de quantidade de movimento, energia e massa. Para a resolução do modelo, as equações são discretizadas usando o método de volumes finitos em um domínio bidimensional composto por ar e gelo poroso. A interface móvel ar-gelo é tratada utilizando a formulação de malha fixa. O domínio computacional inclui a região frontal das placas planas com a finalidade de estudar o crescimento do gelo poroso nessa região. O código numérico é verificado por partes de acordo com artigos de referência na literatura e o modelo é validado com dados experimentais. Os dados experimentais, reportando temperatura e crescimento de forma locais, coincidem com os resultados numéricos com um erro relativo inferior a 10 \% para o caso intermediário de taxa de umidade / Abstract: In this study, a frost formation model is presented based on a new two-dimensional approach for the growth rate. For modeling the frost formation over parallel cold plates, the basic transport equations of mass, energy and momentum have been discretized using the finite volume method in a two-dimensional domain in which air and frost are considered. A volume tracking method employing a fixed grid formulation is used to deal with the air-frost moving boundary. An extended domain in the inlet boundary has been considered in order to study the frost formation in the leading edge of the plate. The numerical code is gradually verified using benchmarking references. The numerical results have been validated against experimental data in which frost growth and temperature as a function of time are reported as local values. The model predictions of the frost thickness as a function of time agree with the experimental data within 10 \% of deviation for the case of intermediate humidity ratio / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / The recent climate change has forced people to live in extreme conditions, either excessive heat or cold, implying that they must adapt to survive in these situations. However, there are people who, because of their geographical condition and lack of resources, lack the means and tools to combat these climate changes. The context of this study is provided in a rural town located in the Arequipa region (Peru), whose inhabitants have to fight against frosts of up to −20 °C in an area without electricity. A viable solution to this problem is found through the design and implementation of a heating system using geothermal and photovoltaic energy, which are resources found in the area, according to a report of the Ministry of Energy and Mines. This study analyzes and researches the geographical and meteorological conditions of the region, for validating, through theory and simulations, whether the proposed system can supply the thermal energy required to maintain the indoor temperature at a minimum of 15 °C under extreme conditions. The system is designed after analyzing the best technological options and techniques currently available in the context studied for its ultimate financing and establishing guidelines and indicators for monitoring results.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / The recent climate change has forced people to live in extreme conditions, either excessive heat or cold, implying that they must adapt to survive in these situations. However, there are people who, because of their geographical condition and lack of resources, lack the means and tools to combat these climate changes. The context of this study is provided in a rural town located in the Arequipa region (Peru), whose inhabitants have to fight against frosts of up to −20 °C in an area without electricity. A viable solution to this problem is found through the design and implementation of a heating system using geothermal and photovoltaic energy, which are resources found in the area, according to a report of the Ministry of Energy and Mines. This study analyzes and researches the geographical and meteorological conditions of the region, for validating, through theory and simulations, whether the proposed system can supply the thermal energy required to maintain the indoor temperature at a minimum of 15 °C under extreme conditions. The system is designed after analyzing the best technological options and techniques currently available in the context studied for its ultimate financing and establishing guidelines and indicators for monitoring results.

No description available.

No description available.

Improvements in the strength and durability of frost-susceptible soils and aggregates can be achieved through chemical stabilization using portland cement, where the efficacy of cement stabilization for improving durability depends on the degree to which hydraulic conductivity is reduced. Hydraulic conductivity is commonly estimated from basic soil properties using Moulton's empirical equation. However, the hydraulic conductivity estimation does not consider the detrimental effects of freezing or the benefits of cement stabilization. The purpose of this research was to derive new equations relating hydraulic conductivity after freezing to specific material properties of cement-treated soils and aggregates stabilized with different concentrations of cement. This research included material samples from two locations in Alaska and from single locations in Minnesota, Montana, Texas, and Utah, for a total of six material samples. Each soil or aggregate type was subjected to material characterization by the Unified Soil Classification System (USCS) and the American Association of State Highway and Transportation Officials (AASHTO) classification system. Moisture-density curves were developed, and unconfined compressive strength (UCS) testing was performed to determine cement concentrations generally corresponding to low, medium, and high 7-day UCS values of 200, 400, and 600 psi, respectively. After being cured for 28 days at 100 percent relative humidity, the prepared specimens were subjected to frost conditioning and hydraulic conductivity testing. The Alaska-Elliott, Minnesota, Montana, and Utah materials exhibit decreasing hydraulic conductivity with increasing UCS, the Texas material exhibits increasing hydraulic conductivity with increasing strength from the low to medium cement concentration levels but decreasing hydraulic conductivity from the medium to high cement concentration levels, and the Alaska-Dalton material exhibits increasing hydraulic conductivity with increasing strength. Multivariable regression analyses were performed to investigate relationships between hydraulic conductivity and several material properties, including soil gradation and classification, fineness modulus, specific gravity, cement content, porosity, compaction method, dry density, and 7-day UCS for each specimen. The R2 values computed for the six-parameter, four-parameter, USCS, and AASHTO-classification models are 0.795, 0.767, 0.930, and 0.782, respectively. Further research is recommended to investigate the effects of cement on hydraulic conductivity for USCS and AASHTO soil types not covered in this research.