<p>The goal of this thesis is to make an unmanned ground vehicle (UGV) follow a given reference trajectory, without colliding with obstacles in its way. This thesis will especially focus on modeling and controlling the UGV, which is based on the power wheelchair Trax from Permobil.</p><p>In order to make the UGV follow a given reference trajectory without colliding, it is crucial to know the position of the UGV at all times. Odometry is used to estimate the position of the UGV relative a starting point. For the odometry to work in a satisfying way, parameters such as wheel radii and wheel base have to be calibrated. Two control signals are used to control the motion of the UGV, one to control the speed and one to control the steering angles of the two front wheels. By modeling the motion of the UGV as a function of the control signals, the motion can be predicted. A path following algorithm is developed in order to make the UGV navigate by maps. The maps are given in advance and do not contain any obstacles. A method to handle obstacles that comes in the way is presented.</p>

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 114-121). Also available on the Internet.

Thesis (M.A.)--Portland State University, 2002. / Computer-produced typeface. Includes bibliographical references (leaves 119-123).

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 114-121). Also available on the Internet.

Muskeg or peat deposits cover large areas in northern Manitoba. Test sections of a newly constructed highway on peat were instrumented to investigate their performance and to develop more economical means of construction method. Test Section ‘A’ was constructed with geotextile base layer while Section ‘B’ was with geotextile and corduroys (timber logs). The test sections were constructed during winter for ease in mobilizing construction equipment at the site when the ground was frozen and were instrumented to observe its behaviour and performance. Settlements were measured using monitoring plates and pins. Ground temperatures were measured using thermistors. Porewater pressures were measured using vibrating wire piezometers. Peat in the study area has an average thickness of 4m, with the upper layer classified as fibrous and the lower layer as amorphous with strong to complete decomposition. Standard laboratory tests were conducted on bored samples from the site. Hydraulic conductivity tests were carried out at different vertical pressures to determine its permeability. Thermal conductivity was determined at frozen and unfrozen state of peat. Conventional incremental oedometer tests were conducted to determine the compressibility parameters and secondary compression indices of the peat layers. Constant-rate-of-strain (CRS) tests were also performed to supplement the results obtained from the conventional method. Isotropically-Consolidated Undrained (CIŪ) triaxial tests were carried out to determine the shear strength of peat. A commercially-available computer program was used in the numerical modelling to simulate the field performance of the instrumented sections. The results from numerical modelling were reasonably close to the measured values in the field. Laboratory-scale physical modelling was undertaken to understand further the operating mechanisms involved in the performance of the two test sections under a more controlled environment. Artificial transparent clay that has similar deformation properties with most of the natural clays and peats was used as foundation material. It allows determination of spatial deformations beneath the embankment using Particle Image Velocimetry (PIV) technique. The load-settlement behaviour in the field was also reasonably simulated in the laboratory-scaled physical model. Deformation patterns from PIV indicate that embankment with geotextile layer and corduroy has smaller settlements and lateral movements in the foundation compared to that of the embankment with only geotextile layer.

The extent and dynamics of permafrost are tightly linked to the distribution and movement of water in arctic landscapes. As the Arctic warms more rapidly than the global average, profound changes are expected in both permafrost and hydrology; however, much is still not known about the interactions between these two systems. The aim of this thesis is to provide new knowledge on the links between permafrost and hydrology under varying environmental conditions and across different scales. The objectives are to (i) determine how permafrost distributions and patterns in morphology are linked to hydrology, (ii) determine how groundwater flow influences ground temperature dynamics in permafrost landscapes, and (iii) explore the mechanisms that link permafrost to groundwater and streamflow dynamics. A range of methods have been applied within the four studies (papers I-IV) comprising the thesis: geophysical (ground penetrating radar and electrical resistivity tomography) and GIS techniques for mapping and analyzing permafrost distributions and related morphology; numerical modeling of coupled heat and water fluxes for mechanistic understanding permafrost-hydrological links; and statistical analyses for detecting trends in streamflow associated with permafrost thaw. Combining these various methods here allows for, and may be considered a prerequisite for, novel insights to processes. The thesis also presents statistical analyses of field observations of ground temperatures, ground- and surface water levels, as well as lake and shore morphological variables. Discontinuous permafrost peatlands are heterogeneous environments regarding permafrost distributions and thickness which is manifested in surface systems such as lake geometries. In these environments, lateral groundwater fluxes, which are not considered in most permafrost models, can significantly influence ground temperature dynamics, especially during high groundwater gradient conditions. River discharge data provide a potential for monitoring catchment-scale changes in permafrost, as the magnitude and seasonality of groundwater fluxes feeding into streams are affected by the distribution of permafrost. This thesis highlights the need to understand water and permafrost as an integrated system with potential internal feedback processes. For example, permafrost thaw can lead to increases in groundwater discharge which in turn can lead to increased heat transfer through the ground, resulting in further acceleration of permafrost thaw rates. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.</p>

In many wireless devices, antennas occupy the majority of the overall size. As compact device sizes become a greater focus in industry, the demand for small antennas escalates. In this thesis, detailed investigations on the design of a planar meandered line antenna with truncated ground plane and 3D dipole antenna at 2.4 GHz (ISM band) are presented. The primary goal of this research is to develop small, low coast, and low profile antennas for wireless sensor applications. The planar meandered line antenna was designed based on a study of different miniaturization techniques and a study of the ground plane effect. The study of the ground plane effect proved that it has a pivotal role on balancing the antenna current. The study of the miniaturization process proved that it affects directly the gain, bandwidth, and efficiency. The antenna efficiency and gain were improved using the truncated ground plane. This antenna has a measured gain of -0.86 dBi and measured efficiency of 49.7%, making it one of the efficient and high gain small antennas. The 3D dipole antenna was designed using a novel method for efficiently exploiting the available volume. This method consists of fabricating the dipole on a cube configuration with opening up the internal volume for other uses. This antenna was tested, and it was found that this antenna has good radiation characteristics according to its occupied volume. Ka of this antenna is 0.55, its measured gain is 1.69 dBi with 64.2% measured efficiency. Therefore, this design is very promising in low-power sensing applications. A Wheeler Cap was designed for measuring the efficiency and the 3-antenna method was used for measuring the designed antennas gain.

Ground-water conductivity data were obtained from shallow wells in a 12 km2 stream-basin along a 400 m transect, extending from the divide to the stream. The stream, Pringle Branch, is a second-order perennial stream in Hillsborough County, Florida. The shallow stratigraphy consists of 2-3 m of fine sand over a layer of clayey silt and silty clay. Vegetation cover includes grasses on the upper and middle slope, and riparian woodlands on the foot slope and floodplain. Precipitation is about 1.3 m per year. Shallow ground-water conductivity is about 50 uS/cm at the divide. It increases moderately along the mid slope, then increases markedly within the riparian woodlands, reaching a maximum of about 500 uS/cm at 30m from the stream and then decreases to about 150 uS/cm at the stream. The spatial variation of terrain electrical conductivity data collected using electromagnetic methods (EM 31) is similar to the spatial variation of ground-water conductivity.Dry season through wet season monitoring shows that ground-water conductivity in each well varies about 40%, generally following variations in potential evapotranspiration (ETpan). The more than five-fold increase in ground-water conductivity from divide to riparian woodlands is maintained during both dry and wet seasons. The ground-water conductivity in this basin appears to be determined principally by spatial variations in ET and not by temporal variations in ET or interaction with soil minerals. The data suggest that patterns of ground-water conductivity can be used to infer patterns of ET variation within a small basin. A mass transport model constructed to test the hypothesis that evapotranspiration has the dominant effect on ground-water conductivity closely duplicates the observed variation in ground-water conductivity from divide to stream. The model uses two evaporation rates, 0.73 m/y for the grasses and 1.46 m/y for the riparian woodlands, and no contribution from solution of matrix materials.

Ground source heat pumps (GSHP) are efficient alternatives to air source heat pumps to provide heating and cooling for conditioned buildings. GSHPs are widely deployed in the midwest and eastern regions of the United States but less so in Texas and the southwest regions whose climates are described as being semi-arid. In these semi-arid regions, building loads are typically cooling dominated so the unbalance in energy loads to the ground, coupled with less conductive soil, cause the ground temperature to increase over time if the ground loop is not properly sized. To address this ground heating problem especially in commercial building applications, GSHPs are coupled with supplemental heat recovery/rejection (SHR) systems that remove heat from the water before it is circulated back into the ground loops. These hybrid ground source heat pump systems are designed to reduce ground heating and to lower the initial costs by requiring less number of or shallower boreholes to be drilled. This thesis provides detailed analyses of different SHR systems coupled to GSHPs specifically for residential buildings. The systems are analyzed and sized for a 2100 ft2 residential house, using Austin, Texas weather data and ground conditions. The SHR systems investigated are described by two heat rejection strategies: 1) reject heat directly from the water before it enters the ground loops and 2) reject heat from the refrigerant loop of the vapor compression cycle (VCC) of the heat pump so less heat is transferred to the water loop at the condenser of the VCC. The SHR systems analyzed in this thesis are cooling towers, optimized VCC, expanded desuperheaters and thermosyphons. The cooling towers focus on the direct heat rejection from the water loop. The VCC, desuperheater, and thermosyphon systems focus on minimizing the amount of heat rejected by the VCC refrigerant to the water loop. In each case, a detailed description of the model is presented, a parametric analysis is provided to determine the amounts of heat that can be rejected from the water loop for various cases of operation, and the practical feasibility of implementation is discussed. An economic analysis is also provided to determine the cost effectiveness of each method. / text

Ground state depletion with individual molecule return (GSDIM) super-resolution microscopy is used to interrogate the location of individual fluorescence bursts from two different nanoparticle-fluorophore systems. The first system consists of fluorophore-labeled DNA molecules on gold nanowire surfaces. In this system carboxytetramethyl rhodamine-labeled double-stranded DNA molecules were bound to the surface of gold nanowires via gold-thiol linkages. The second system focuses on mesoporous silica coated nanorods with dye embedded into the silica coating. The dye molecule, Rhodamine 6G, was incorporated into the silica shell during the nanorod coating procedure. Individual fluorescence bursts were spatially localized using point spread function fitting and used to reconstruct the image of the underlying nanowire or nanorod. / text