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20th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems
- Conference date: 01 Apr 2007 - 05 Apr 2007
- Location: Denver, Colorado, USA
- Published: 01 April 2007
161 - 164 of 164 results
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Model-Based Uncertainty In Surface Wave Inversion
Authors Glenn J. Rix and Carlo G. LaiMost surface wave inversion algorithms used for geotechnical site characterization are based on a subsurface model consisting of a stack of homogeneous layers with constant shear wave velocity. In reality, the shear wave velocities and other parameters are likely to vary continuously with depth. The difference between the actual site conditions and assumed model is a source of uncertainty in surface wave testing. In this study, a surface wave inversion algorithm based on a subsurface model in which the material properties vary continuously with depth is developed and illustrated for two sites.
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Geophysics Research At Estcp And Serdp
Authors Anne M. Andrews and Jeffrey MarquseeThe Strategic Environmental Research and Development Program (SERDP) and the Environmental Security Technology Certification Program (ESTCP) are DoD research programs that
share the mission of developing and demonstrating advanced technologies applicable to DoD environmental challenges. In the area of munitions response, the programs are largely concentrated on the application of geophysics to the detection and characterization of buried munitions.
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Uxo Clusters And Sheet-Like Anomalies In Wide-Area Assessment Surveys
More LessThe objective of many recent UXO surveys has been described as “wide-area assessment” with the purpose of obtaining better definition of a known problem area. The targets of interest are clusters of ordnance, frag and debris which are all indicators of greater contamination, higher risk of UXO hazard and higher remediation or construction costs. This is a different problem from the detection and discrimination of individual anomalies. This paper provides a definition of a “cluster” based on the amount of overlap between individual dipole signatures. With spacing of individual sources closer than 0.5 times the sensor height, their magnetic anomalies overlap significantly and increase the response amplitude. The result is comparable to a horizontal sheet of dipoles. The equations to simulate a horizontal sheet are derived, and from these the relative density of targets may be calculated from the measured data by assuming a nominal target moment or vise versa. A field test supports both the qualitative and quantitative theory. Finally, in practice QA/QC metrics should represent the targets of interest, which means creating
dense grids of surface frag. For detection of clusters, the concepts of detection probability and search radius based on single items are irrelevant. Likewise, discrimination techniques that rely on dipole fitting will be extremely inaccurate. Instead, QA parameters and models suitable for horizontal sheets will have to be derived.
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Rapid Wide Area Assessment For Large Surface Munitions Via An Infrared Surveillance System
The purpose of this study is to determine the feasibility of using a commercially available thermal infra-red surveillance system for detecting large surface munitions as part of an UXO Wide
Area Assessment. The work was performed in partnership with multiple US Army Corps of Engineers agencies and the Isleta Pueblo. The area of interest is located on the Isleta Pueblo. The US Army Engineer Research and Development Center team flew a low cost airborne surveillance system (Ultra 8500 FW) on a single engine fixed-wing aircraft over the area of interest. The airborne missions were scheduled to maximize the thermal separation between the UXO and the natural surroundings based on diurnal data collections. The flight profiles were collected at approximately 700 feet above ground level at an approximate ground speed of 100 knots in both contour following and parallel transects depending on the terrain. The thermal signatures were recorded on digital media and frames containing potential UXO (both targets and false alarms) will be selected for field verification by Shaw Environmental, Inc. Examples of the data collected, advantages and disadvantages of utilizing the thermal airborne system, video format and compression artifacts, and field verifications will be shown.
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