Thesis (Ph. D.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains x, 117 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 110-114).

Ground Penetrating Radar (GPR) methods have been used to evaluate the presence, extent, and spatial variability of hydrophobic soils in Southern California Watersheds. It has been shown that high frequency ground penetrating radar equipment, under certain conditions, has the ability to determine the presence, depth, and persistence of post fire hydrophobic soils. As part of this study an extensive investigation was undertaken to not only evaluate the capability of this approach but also to understand under what conditions the method can be applied successfully and what are the limitations of the approach. The investigation includes use of computer simulations and modeling, laboratory investigations in sand boxes with native soils, and multiple field trials spanning a five year time period. Of particular significance is the finding that using GPR it is possible to: locate the interface between the uppermost burnt soil layer, and soil horizons below; quantify the depth at which the hydrophobic layer forms; and quantify the spatial extent of the layer. As part of this study best practice methods for both field and lab experimentation have also been developed and are presented in the body of the thesis. Based on this study it is concluded that the use of GPR can provide a much more accurate and comprehensive method of evaluating the nature of hydrophobic layers in such environments than the current point specific manual methods. As a result the use of GPR has significantly advanced our capacity to assess the potential for increased erosion and the generation of debris flows in such environments after rainfall events.

Advanced nondestructive inspection techniques like stress wave timing and resistance microdrilling have been used to successfully inspection timber bridges, but it is most effective on girder style bridges. There is a noted need to develop additional inspection techniques for longitudinal deck/slab timber bridges, which comprise about 20% of the national bridge inventory. One technique that holds potential is ground penetrating radar, a recognized nondestructive testing technique that has been used effectively for many different environmental and transportation applications. It has been utilized successfully to identify buried objects, internal defects and material changes. The objective of this research was to assess the potential for using GPR to identify and assess simulated deterioration in longitudinal timber deck timber bridges. GPR scans were completed in the longitudinal and transverse directions of a screwlaminated timber bridge deck before and after a bituminous layer was added to assess embedded defects that simulated voids, decay, insect damage and horizontal shear splitting. Assessment of the GPR wave energy signal was completed using visualization software that was provided with the commercial GPR unit used for the testing. The radar signal was analyzed in both the longitudinal direction (antenna front to back) and the transverse direction (antenna side to side). Interpretation of the radar signals allowed for the identification of various internal defects present in the deck. Based on the results, GPR has the potential to identify internal defects in timber bridge decks before and after a bituminous layer was added. Large, rectangular void defects (at least 6? by 12? by 5 in. (15.2? by 30.4? by 12.7 cm)) that were hollow, filled with foam, or filled with sawdust/adhesive were most easily identified under all scanning conditions. The addition of a bituminous layer, common to slab bridge construction, damped the signal response and made it more difficult to identify defects. Several smaller defects that were found in the deck without a bituminous layer were not identified in scanning completed after the bituminous layer was added.

The use of geophysical tools to locate clandestine burials involving bodies has seen increasing popularity among forensic personnel. Often, these search methods are important to highlight certain areas where a body may or may not be located prior to utilizing invasive search techniques. Because of the success of these tools within real-life forensic searches, the use of controlled studies that monitor and detect cadavers over certain lengths of time have been increasingly utilized. However, these controlled studies have not monitored various burial scenarios that mimic real-life situations. This study focused on detecting and monitoring six burials containing pig carcasses used as proxies for human bodies and two control burials with a conductivity meter and ground-penetrating radar (GPR) with a 500-MHz and a 250-MHz antenna over a twelve month period. Each burial within this study represented a different forensic scenario that mimicked a real-life situation. Further, forensic use of GPR in both controlled settings as well as real-life searches have mainly focused on the use of a 500-MHz antenna. Therefore, this research also compared the use of a 250-MHz antenna with a 500-MHz antenna. Lastly, a number of GPR imagery options were utilized including reflection profiles and horizontal slices with various GPR software programs to compare the results obtained. Results obtained from the conductivity meter were compared to the results obtained by both antennae of the GPR. Overall, the use of multiple GPR imagery options provided increased resolution of the burial scenarios. Results showed that the conductivity meter was not a beneficial geophysical tool because none of the burial scenarios were detected. On the other hand, the use of GPR showed that the graves with objects added to the pig carcasses provided iv increased resolution compared to the graves containing only pig carcasses. Lastly, the 250-MHz antenna provided better resolution of the burial scenarios than the 500-MHz antenna due to easier discrimination of the forensic targets. Therefore, the use of a 250-MHz antenna would be a viable option to search for clandestine burials containing adult-sized bodies

<p>Interception av snö eller regn på trädkronor är en viktig del av det hydrologiska kretsloppet. Upp till en tredjedel av all snö som faller över skogsområden når aldrig marken på grund av stora avdunstningsförluster av interceptionsförrådet, vilket minskar vårflöden i älvar. Goda prognoser av dessa flöden är viktiga för vattenkraftsindustrin. För att kunna förbättra modeller, i vilka interceptions-avdunstningsprocessen ingår, krävs lämpliga mätmetoder för interceptionförrådet av snö. Syftet med detta arbete var att undersöka om impulsradarutrustning kan användas för att mäta interceptionsförrådet av snö på barrträd. Metoden bygger på att mäta hastigheten och utsläckningen hos en elektromagnetisk impulsvåg, vilken skickas från en sändarantenn genom ett avsnitt skog till en mottagarantenn. Både utsläckningen och hastigheten påverkas av snö och vatten på trädens kronor, och kan med så kallade blandningsformler relateras till mängd vatten. Blandningsformler beskriver de elektromagnetiska egenskaperna hos heterogena material. Laboratorietester visade att interception av flytande vatten på små trädkronor gav upphov till förändringar av impulsvågens hastighet och utsläckning mätbara med radarutrustningen. Uppskattningar av mängden intercepterat vatten från radarmätningarna gav en överskattning jämfört med oberoende referensmätningar, däremot stämde relativa variationer väl överens mellan mätningarna. Tydliga samband mellan impulsvågens utsläckning och mängden intercepterat vatten kunde inte bestämmas från experimenten. Utsläckningsresultaten var svårtolkade och lämpliga blandningsformler hittades inte i litteraturen. Metoden testades även en vecka i fält i norra Sverige. Trots att installationen inte var den bästa visade resultaten ändå god överensstämmelse mellan uppskattade förändringar av interceptionsförrådet från radarmätningarna, och observerade väderförändringar samt oberoende referensmätningar med en trädvågsanordning. Resultaten tyder på att metoden kan ge goda uppskattningar av interceptionsförrådet, då en väl fungerande installation av utrustningen används och efter att vidare kalibreringsförsök genomförts.</p> / <p>Interception of rain or snow in forest canopies is an important component of the hydrological cycle. Up to one third of the total winter precipitation never reaches the ground in forest areas due to evaporation losses of intercepted snow, which reduces spring-time water flow in rivers. Accurate spring flow predictions are important for the hydro-power industry. Appropriate measurement methods of intercepted snow are needed in order to improve models involving the interception evaporation process. The aim of this study was to explore the possibilities of an impulse radar system to measure the snow interception storage on coniferous trees. The method is based on measurements of the velocity and attenuation of an electromagnetic impulse wave, generated in a transmitting antenna and sent through a forest section and detected by a receiving antenna. The attenuation and velocity is affected by ice and water in the canopy air space, and can be related to amounts of water using so-called mixing formulas that describe the average electromagnetic properties of heterogeneous materials. Controlled laboratory measurements on small canopies showed that interception of liquid water was well above the detectable limits of the radar system, with respect to both attenuation and velocity changes. Estimations of the mass of intercepted water based on velocity changes overestimated the reference measurements, but relative variations were well captured. No clear relation could be found between amount of water on canopies and impulse wave attenuation from the experiments. The attenuation results were difficult to interpret, and appropriate mixing formulas were not found in the literature. The method was further tested for one week under field conditions in northern Sweden. In spite of a non-optimal equipment installation results of estimated changes of the interception storage showed a good agreement with observed weather variations and reference measurements using a tree weighing device. The method can have good conditions to give correct estimations of the snow interception storage, using appropriate installation and further calibration measurements.</p>

Thesis (M.S)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains xi, 104 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 69-70).

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains x, 100 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 83-86).

This thesis reports on the investigations of resistive-capacitive (RC) loaded bow-tie antennas with special emphasis on impulse ground penetrating radar applications. Impulse radiation for ground penetrating radar is a challenging research topic because of the unique problem arising from impulse radiation: late-time ringing, which usually masks the important echo signals from the targets. While resistive loading is a common solution for eliminating late-time ringing, use of resistive loading typically sacrifices the radiation efficiency. In this thesis, a resistive-capacitive loading technique is investigated for a circular bow-tie antenna in the attempt to reduce/suppress the late-time ringing as well as to maintain a relatively high radiation efficiency. To implement the system, a microstrip differentiator, which converts a monopulse into a Gaussian-like monocycle to be used as input impulse, is presented. Further, specially designed coplanar waveguide/coplanar strip (CPW/CPS) baluns embedded with Chebyshev transformers of characteristic impedance up to 120 have been constructed and tested. To evaluate the system, instead of using the conventional peak voltage value of the radiated waveform, average radiated energy, average ringing energy, relative radiation efficiency and relative ringing efficiency are utilized and these metrics are easily established using low-cost low-sensitivity probes. Measurement results show that the RC-loading scheme is functioning as expected and the impulse system as a whole is capable of reducing the late-time ringing energy to 50% while maintaining average radiation energy as 83% when compared with capacitive loading cases. / October 2006

Peatlands provide a variety of ecosystem services including carbon sequestration, nutrient cycling and increased biodiversity, and are thus an important Canadian natural resource. Mountain peatlands, including those in the foothill region of the Canadian Rockies are particularly important due to their proximity to headwater streams which supply the Prairie Provinces with water. Yet, distribution of peatlands in the Canadian Rocky Mountains is unknown. There is also a lack of understanding of the form of these peatlands and the processes influencing them. The purpose of this research is to improve our understanding of Canadian mountain peatlands in terms of their abundance, distribution and subsurface form. Specific objectives are to: determine the distribution of beaver impacted wetlands in the study area; quantify the proportion of these which are peatlands; determine the impact beaver have on one hydrological variable, the area of open water and; describe the stratigraphy of peatlands with beaver at their surface. Beaver impacted wetland distribution was assessed through manual analysis of georeferenced aerial photographs. Combining these data with an existing GIS layer provided the basis of a wetland inventory of the region, allowing wetlands to be separately inventoried by physiographic location (Mountain and Foothills) and jurisdiction (Alberta Parks, Municipal Districts, Improvement Districts and First Nations Reserve). Approximately 75% of wetlands are located in the Foothills and Municipal District areas. Beaver impact is evident in 30% of the 529 wetlands inventoried, with the highest number in protected areas. Area of open water on wetlands, as assessed by manual analysis of aerial photographs, indicated that beaver impacted sites have on average approximately ten times more open surface water area than non- beaver impacted sites. In total, 81 wetlands were ground-truthed of which 77% were peat-forming wetlands or peatlands. Ground penetrating radar surveys and soil coring performed at 9 peatlands with beaver activity at their surface showed structural differences from those peatlands for which ecosystem services are described in the literature in that they are stratigraphically complex. Little is known about the factors affecting how this form develops, and this requires further study. The distribution of peatlands in the study area highlights them as important landscape units, and that in order to best manage them, further research is required into the various influences on their hydrological and ecological function.

This thesis reports on the investigations of resistive-capacitive (RC) loaded bow-tie antennas with special emphasis on impulse ground penetrating radar applications. Impulse radiation for ground penetrating radar is a challenging research topic because of the unique problem arising from impulse radiation: late-time ringing, which usually masks the important echo signals from the targets. While resistive loading is a common solution for eliminating late-time ringing, use of resistive loading typically sacrifices the radiation efficiency. In this thesis, a resistive-capacitive loading technique is investigated for a circular bow-tie antenna in the attempt to reduce/suppress the late-time ringing as well as to maintain a relatively high radiation efficiency. To implement the system, a microstrip differentiator, which converts a monopulse into a Gaussian-like monocycle to be used as input impulse, is presented. Further, specially designed coplanar waveguide/coplanar strip (CPW/CPS) baluns embedded with Chebyshev transformers of characteristic impedance up to 120 have been constructed and tested. To evaluate the system, instead of using the conventional peak voltage value of the radiated waveform, average radiated energy, average ringing energy, relative radiation efficiency and relative ringing efficiency are utilized and these metrics are easily established using low-cost low-sensitivity probes. Measurement results show that the RC-loading scheme is functioning as expected and the impulse system as a whole is capable of reducing the late-time ringing energy to 50% while maintaining average radiation energy as 83% when compared with capacitive loading cases.