No description available.

No description available.

No description available.

Double-screw vehicles have been developed to operate in soft, wet terrains such as marsh, snow, and water. Their exceptional performance in soft and wet terrains is at the expense of performance on rigid terrains such as pavement. Furthermore, turning can be difficult because the method of turning varies depending on the terrain. Therefore, in this study, several different quad-screw-configurations were proposed and tested to improve upon double-screw vehicles. A test-bed was developed which could easily be converted into each quad-screw-configuration for testing on a variety of surfaces (grass, dirt, sand, clay, marsh, snow, gravel, pavement, and water). In addition, a force-vector analysis was performed for each screw-configuration to predict and understand performance in different terrains. From the testing and analysis, the inline-screw configuration was the most versatile because it was omnidirectional on all surfaces but water and pavement. Regardless, it was fully capable of navigating water, both on the surface and submerged, and pavement by rotating about its center.

Soil moisture is a key variable in off-road mobility. Mobility analysis was conducted based on three soil moisture sources: WindSat (a satellite), LIS (a computer model), and in situ ground sensors (assumed to represent ground truth). Mobility of six vehicles, each with different ranges of sensitivity to soil moisture, was examined in three test sites. Two methods were used: a simplified method based on time series and a fulleatured terrain method. The results demonstrated that the effect of the soil moisture error on mobility predictions is complex and may produce very significant errors in mobility analysis for certain combinations of vehicles, seasons, and climates. Soil moisture biases vary in both direction and magnitude with season and location. Furthermore, vehicles are sensitive to different ranges of soil moistures. In the wet season, differences in soil strength resulted in more significant differences in mobility predictions than in the dry season.

Advancements in computation and development of physically based hydrologic models to simulate complex vadose zone scenarios helped the research community to evaluate different scenarios easily compared to long-term field experiments. However, some field data collection is necessary to obtain input data such as soil properties, water usage and land management practices to validate the model performance specific to the site. Data obtained from field experiments conducted in 2011 at Hespler farms, Winkler, MB was used in this research for model calibration and validation. The hydrologic model, HYDRUS (2D/3D) was evaluated using parameters such as visual and statistical analysis. Model evaluation during the calibration and validation stage gave RMSE values of 0.019 and 0.015 cm3 cm-3; PBIAS values of -1.01 and -0.14, respectively, suggesting that the model was efficient in simulating soil water content similar to the field observed data. The validated models were then used to simulate outcomes for different scenarios such as 30-year rainfall data (1986 – 2015), different soil physical properties, and drainage system design parameters. Models simulating free drainage predicted lower soil water content compared to controlled drainage leading to 6 – 60 more trafficable days for 8 m spacing and 0.9 drain base depth. Free drainage predicted 8 – 110 additional trafficable days compared to controlled drainage for 15 m spacing and 1.1 drain depth. Heavier than normal rainfall events caused high water contents leading to a few years with a very low to no trafficable days under controlled drainage conditions. The comparisons are presented based on models using free drain conditions. Models with 8-m drain spacing predicted a 1 to 10-day increase in the number of trafficable days compared to the 15-m drain spacing. Drains placed at a base depth of 1.1 m below the soil surface predicted 4 - 40 more trafficable days compared to those installed at a base depth of 0.9 m. / October 2017

Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on November 6, 2007) Includes bibliographical references.

Made available in DSpace on 2016-06-02T20:00:35Z (GMT). No. of bitstreams: 1 3385.pdf: 6627398 bytes, checksum: 174c162bdfb9df01233767304d7a693d (MD5) Previous issue date: 2010-10-25 / The reality of pavement in médium and small brazilian cities is the execution of urban roads devoid of study, planning and sizing. This situation occurres a less useful life, a big maintenance cost and a big environmental degradation. Concerning this situation, allied the fact of the financial resources are usually insufficient since there is also the necessity of improvement in other social areas like basic sanitation, health and education, this work searches to establish guideline to help minicipal administrations to choose better the type of pavement to be used, concerning the trafficability, environmental and economic aspects. It is still imperative, it notes the cost of new ambiental requirement in the execution of paviments generating main for production process, and for taxes quarterly collected for the public organ. This study contemplates the interlocked and bituminous (bituminous hot machined concrete) pavements. It is presented a study of case in Passos city, Minas Gerais, searching to do a comparative analysis of these two types of pavements accomplishment. The result permited to collect an extense group of variables that can be used for definition of economic, tafficability and environmental aspects. It also permited a satisfatory evaluation of choosed methods for comparative analysis done by case study. / A realidade da pavimentação na maioria das cidades brasileiras de pequeno e médio porte geralmente é a execução das vias urbanas desprovidas de estudo, planejamento e dimensionamento. Esta situação ocasiona menor vida útil dos pavimentos, alto custo de manutenção, e maior degradação ambiental. Considerando este cenário, aliado ao fato de que os recursos financeiros destinados para a pavimentação urbana são em geral insuficientes, visto que também há uma grande necessidade de melhoria em outras áreas sociais, como saneamento básico, saúde e educação, este trabalho busca estabelecer diretrizes para auxiliar as administrações municipais a escolher melhor o tipo de pavimento a ser utilizado, considerando os aspectos de trafegabilidade, ambientais e econômicos. É ainda imperativo observar os custos das novas exigências ambientais na execução dos pavimentos, gerados principalmente pelo encarecimento de adequação do processo de produção, e pelas taxas cobradas trimestralmente e recolhidas para os órgãos ambientais. Este estudo contempla os pavimentos intertravados e betuminosos (tratamento superficial duplo e concreto betuminoso usinado à quente). É apresentado um estudo de caso na cidade Passos, no estado de Minas Gerais, buscando fazer uma análise comparativa do desempenho destes dois tipos de pavimentos. O resultado permitiu reunir um conjunto extenso de variáveis que podem ser usadas na definição dos aspectos econômico, de trafegabilidade e ambiental. Permitiu também a avaliação satisfatória dos métodos escolhidos para análise comparativa feita pelo estudo de caso.

With advances in modern technology, satellite-based data is rapidly becoming a viable option for geotechnical site characterization. Commercial satellite data offers high resolution (~25-200 cm), increased spatial coverage on the order of kilometers, short revisit times leading to high temporal coverage, and allows for data to be analyzed rapidly and remotely without the need for physical site access. These advantages are particularly attractive for characterizing coastal sites, where both the strength properties and moisture content can change rapidly in response to tidal stages, wave runup, and storm events. To date, there have been limited investigations into the use of satellite-based data for characterizing geotechnical properties of sandy beach sediments. Furthermore, the use of these moisture contents to estimate the soil strength of beaches has been limited. The goal of this research was to develop pathways to estimate the moisture content of sandy beach sites utilizing satellite-based data. For this study, both optical and synthetic aperture radar (SAR) images were collected at two sites: the Atlantic beach near the US Army Corps of Engineers Field Research Facility in Duck, North Carolina and three distinct sites located near Yakutat, Alaska (Cannon Beach, Ocean Cape, and Point Carrew). During satellite overflight, ground measurements of moisture content, grain size, unit weight, porosity, and bearing capacity were collected. Using the field measurements, this research (1) developed a framework to estimate the moisture content of sandy beach sediments from satellite-based optical images; (2) investigated the necessary collection parameters to estimate the moisture content from SAR images; and (3) developed a framework to estimate the bearing capacity of sandy beaches using moisture contents derived from satellite-based images. The results of this study demonstrated that optical images can produce reasonable estimates of the moisture content when compared to field measurements and are strongly influenced by local morphology. Additionally, SAR images with incidence angles of 30°-50° produced the best results when compared to field measurements. Finally, using the spatial estimates moisture content produced from satellite data and standard sediment, maps of bearing capacity can be developed to predict beach trafficability. / Doctor of Philosophy / The strength of sandy beaches is impacted by the density, particle size and shape, distribution of grain sizes, mineralogy, and moisture content. For coastal sites, which typically have a dominant mineralogy and a limited range of grain sizes, a main factor changing is the moisture content. This varying moisture content can result in the increase or decrease in soil strength, and impacts modelling for coastal challenges such as erosion or beach trafficability (i.e., the ability to drive on the beach) on large scales. It is common to measure moisture content through sampling or moisture probes, but these represent point measurements and may not accurately capture the spatial and temporal moisture contents at a beach. Recently, satellite-based images have become popular for assessing processes and environmental changes over large areas. However, their use for mapping moisture content at sandy beaches has been limited, and the proper models are unknown. As such, the goal of this research is to investigate the use of satellite images to map moisture content over large areas. For this study, measurements were conducted at two sites: an Atlantic beach located near the US Army Corps of Engineers Field Research Facility in Duck, North Carolina and three distinct sites located near Yakutat, Alaska (Cannon Beach, Ocean Cape, and Point Carrew). Simultaneously with ground measurements, two different types of images were collected. The first, optical data, collects data over the visible (400-700 nm) and near infrared (700-1300 nm) regions of the electromagnetic spectrum. These satellites use the sun to light the scene and the amount of energy reflected back to the satellite is used to estimate the moisture content. The second, X-band synthetic aperture radar (SAR) data (wavelengths of 3.1 cm), sends its own energy source to the ground and uses the returned energy to estimate the moisture content. Both optical and SAR are able to produce reasonable estimates of moisture content when compared to field measurements. These estimated values of moisture content are then tested in a model to estimate the sand strength, with those estimated values also following the expected trends. Ultimately, this work can be used to contribute to understanding how moisture content varies at sandy beaches and improve trafficability predictions in sandy beach environments.

<p>The main objectives of this work were to investigate Geographical Information Systems techniques for modelling a cross-country trafficability. To accomplished stated tasks, reciprocal relationships between the soil deposits, local hydrology, geology and geomorphology were studied in relation to the study area in South-Eastern Sweden.</p><p>Growing awareness of nowadays users of GIS in general is being concentrated on understanding an importance of soil conditions changed after cross-country trafficability. Therefore, in this thesis, constructing of the Soil Knowledge Database introduced to the genuine geological soil textural classes a new, modified geotechnical division with desirable for off-road ground reasoning measurable factors, like soil permeability, capillarity or Atterberg’s consistency limits.</p><p>Digital Elevation Model, the driving force for landscape studies in the thesis, was carefully examined together with the complementary datasets of the investigated area. Testing of the elevation data was done in association to the hydrological modelling, which resulted with the Wetness Index map. The three distinguishable soil wetness conditions: dry, moist and wet, were obtained, and used consequently for creation of the static ground conditions map, a visible medium of soils susceptibility to for example machine compaction.</p><p>The work resulted with a conceptual scheme for cross-country trafficability modelling, which was put into effect while modeling in GIS. As a final outcome, by combining all processed data together, derivatives were incorporated and draped over the rendered 3D animating scene. A visually aided simulation enabled to concretized theoretical, hypothetical and experimental outcomes into one coherent model of apprised under Multicriterial Evaluation techniques standardized factor maps for ground vehicle maneuverability. Also further steps of research were proposed.</p>