Roelof Versteeg

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Arsenic concentrations measured by graphite-furnace atomic absorption range from <5 to 900 ug/L in groundwater pumped from 6000 wells within a 25 km 2 area of Bangladesh. The proportion of wells that exceed the local standard for drinking water of 50 ug/L arsenic increases with depth from 25% between 8-10 m to 75% between 15-30 m, then declines gradually to(More)
[1] Arsenic concentrations measured by graphite furnace atomic absorption range from < 5 to 900 mg/L in groundwater pumped from 6000 wells within a 25 km 2 area of Bangladesh. The proportion of wells that exceed the Bangladesh standard for drinking water of 50 mg/L arsenic increases with depth from 25% between 8 and 10 m to 75% between 15 and 30 m, then(More)
Previous work in the Instrumented OilField DDDAS project has enabled a new generation of data-driven, interactive and dynamically adaptive strategies for subsurface characterization and oil reservoir management. This work has led to the implementation of advanced multi-physics, multi-scale, and multi-block numerical models and an autonomic software stack(More)
High frequency asymptotic approximation of the acoustic Green's function leads to eecient modeling and migration methods for primaries only reeection seismograms. A volume (as opposed to interface) oriented description of reeectivity allows symmetry between modeling and migration. With proper selection of amplitudes and dis-cretization, the migration and(More)
1 Abstract The traveltime and amplitude tables required for high frequency asymptotic approximation of the acoustic Green's function may be computed by eecient high order nite diierence solutions of the eikonal and transport equations. A particularly simple implementation is possible under the additional assumptions that incident and reeected rays carrying(More)
the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus, product or process disclosed in this report, or represents that its use by such third party would not(More)
Multi-offset, single-hole, borehole-radar reflection surveys were conducted at the U.S. Hampshire. The study was conducted to evaluate the benefits of applying multi-offset seismic processing techniques to borehole-radar reflection surveys in fractured rock. The multi-offset reflection surveys were conducted in conjunction with a saline tracer-injection(More)
To predict the location of natural resources and reduce the cost of exploration, geophysicists rely on various techniques to map the internal structure of the earth. One common mapping method probes the earth's interior using an acoustic energy source (sound waves). The acoustic waves reeect when they impinge on a location where the acoustic velocity eld(More)
Kirchhoo (high frequency aymptotic) modeling of primaries only reeection seismograms based on a volume (as opposed to interface) oriented description of reeectivity allows symmetry between modeling and migration. With proper selection of amplitudes and discretization, the migration and modeling operations are mathematically adjoint, hence suitable for use(More)
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