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Articles 1 - 8 of 8
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Improving Database Quality Through Eliminating Duplicate Records, Mingzhen Wei, Andrew H. Sung, Martha E. Cather
Improving Database Quality Through Eliminating Duplicate Records, Mingzhen Wei, Andrew H. Sung, Martha E. Cather
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Redundant or duplicate data are the most troublesome problem in database management and applications. Approximate field matching is the key solution to resolve the problem by identifying semantically equivalent string values in syntactically different representations. This paper considers token-based solutions and proposes a general field matching framework to generalize the field matching problem in different domains. By introducing a concept of String Matching Points (SMP) in string comparison, string matching accuracy and efficiency are improved, compared with other commonly-applied field matching algorithms. The paper discusses the development of field matching algorithms from the developed general framework. The framework and corresponding …
Mantle Transition Zone Discontinuities Beneath The Baikal Rift And Adjacent Areas, Kelly H. Liu, Stephen S. Gao
Mantle Transition Zone Discontinuities Beneath The Baikal Rift And Adjacent Areas, Kelly H. Liu, Stephen S. Gao
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Like most other major continental rifts, the Baikal rift zone (BRZ) in Siberia is presumably underlain by a hot and partially molten mantle, which has a reduced seismic velocity relative to surrounding areas. Recent seismic tomography studies, however, gave conflicting results about the depth extent and even the existence of the low-velocity anomaly beneath the BRZ, suggesting that additional constraints are needed. Here we present results from stacking of about 1700 radial P-to-S receiver functions from a single long-running seismic station, TLY, located at the SW tip of Lake Baikal. A clear uplift of the 410 km discontinuity (d410) with …
Microbial Growth And Biofilm Formation In Geologic Media Is Detected With Complex Conductivity Measurements, Caroline A. Davis, Estella A. Atekwana, Eliot A. Atekwana, Lee D. Slater, Silvia Rossbach, Melanie R. Mormile
Microbial Growth And Biofilm Formation In Geologic Media Is Detected With Complex Conductivity Measurements, Caroline A. Davis, Estella A. Atekwana, Eliot A. Atekwana, Lee D. Slater, Silvia Rossbach, Melanie R. Mormile
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Complex conductivity measurements (0.1-1000 Hz) were obtained from biostimulated sand-packed columns to investigate the effect of microbial growth and biofilm formation on the electrical properties of porous media. Microbial growth was verified by direct microbial counts, pH measurements, and environmental scanning electron microscope imaging. Peaks in imaginary (interfacial) conductivity in the biostimulated columns were coincident with peaks in the microbial cell concentrations extracted from sands. However, the real conductivity component showed no discernible relationship to microbial cell concentration. We suggest that the observed dynamic changes in the imaginary conductivity (σ″) arise from the growth and attachment of microbial cells and …
Lessons Learned From The St. Francis Dam Failure, J. David Rogers
Lessons Learned From The St. Francis Dam Failure, J. David Rogers
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
The St. Francis Dam (Fig. 1), a curved concrete gravity structure 209-feet high, located in the mountains about 35 miles north of downtown Los Angeles, failed catastrophically near midnight just before March 12, 1928. The failure released 36,180 acre-feet of water down San Francisquito Canyon on a turbulent 55-mile journey to the Pacifica Ocean near Ventura, killing 450 people. As the deadliest American civil engineering failure of the 20th century, the city of Los Angeles paid more than $7 million in restitution to the victims' families and affected landowners. The sudden failure of a new concrete dam constructed by a …
Induced-Polarization Measurements On Unconsolidated Sediments From A Site Of Active Hydrocarbon Biodegradation, Gamal Z. Abdel Aal, Lee D. Slater, Estella A. Atekwana
Induced-Polarization Measurements On Unconsolidated Sediments From A Site Of Active Hydrocarbon Biodegradation, Gamal Z. Abdel Aal, Lee D. Slater, Estella A. Atekwana
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
To investigate the potential role that indigenous microorganisms and microbial processes may play in altering low frequency electrical properties, induced-polarization (IP) measurements in the frequency range of 0.1 to 1000 Hz were acquired from sediment samples retrieved from a site contaminated by hydrocarbon undergoing intrinsic biodegradation. Increased imaginary conductivity and phase were observed for samples from the smear zone (contaminated with residual-phase hydrocarbon), exceeding values obtained for samples contaminated with dissolved-phase hydrocarbons, and in turn, exceeding values obtained for uncontaminated samples. Real conductivity, although generally elevated for samples from the smear zone, did not show a strong correlation with contamination. …
Effect Of Water Ice Content On Excavatability Of Lunar Regolith, Leslie S. Gertsch, Robert Gustafson, Richard E. Gertsch
Effect Of Water Ice Content On Excavatability Of Lunar Regolith, Leslie S. Gertsch, Robert Gustafson, Richard E. Gertsch
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
The amount of water ice contained within prepared samples of JSC-1 lunar regolith simulant strongly affects the excavatability of the material. As part of a NASA Phase I SBIR project, load-penetration testing of JSC-1 lunar regolith simulant was performed at water ice concentrations ranging from zero to 11% by mass (approximately saturated), after compaction and cooling to simulate probable lunar conditions. After mixing dry JSC-1 simulant with the appropriate amount of water, the samples were individually compressed into containment rings under 48 MPa of pressure. Thermocouples embedded in the samples monitored internal temperature while they were cooled in a bath …
Southern African Crustal Evolution And Composition: Constraints From Receiver Function Studies, Shaji K. Nair, Stephen S. Gao, Kelly H. Liu, Paul G. Silver
Southern African Crustal Evolution And Composition: Constraints From Receiver Function Studies, Shaji K. Nair, Stephen S. Gao, Kelly H. Liu, Paul G. Silver
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Stacking of approximately 1500 radial receiver functions recorded at about 80 broadband seismic stations deployed in southern Africa reveals systematic spatial variations in the ratio of crustal P and S wave velocities (Φ), crustal thickness (H), and the amplitude of the converted Moho phases (R). The eastern Zimbabwe and the southern Kaapvaal cratons are characterized by small H (~38 km), small Φ (~1.73), and large R (~0.15) values, suggesting that the relatively undisturbed Archean crust beneath southern Africa is separated from the mantle by a sharp Moho and is felsic in composition. The Limpopo belt, which was created by a …
Base-Level Buffers And Buttresses: A Model For Upstream Versus Downstream Control On Fluvial Geometry And Architecture Within Sequences, John M. Holbrook, Robert W. Scott, Francisca Oboh-Ikuenobe
Base-Level Buffers And Buttresses: A Model For Upstream Versus Downstream Control On Fluvial Geometry And Architecture Within Sequences, John M. Holbrook, Robert W. Scott, Francisca Oboh-Ikuenobe
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
The effects of downstream base-level control on fluvial architecture and geometry are well explored in several broadly similar sequence-stratigraphic models. Cretaceous Dakota Group strata, U.S. Western Interior, have characteristics reflecting combined downstream and upstream base-level controls that these models cannot address. Particularly, three layers of amalgamated channel-belt sandstone within this group thicken and are continuous for distances (≤ 300 km) along dip that stretch the reasonable lengths for which these models are intended to apply. As well, architecture in up-dip reaches records repeated valley-scale cut-and-fill cycles. This contrasts with equivalent strata down dip which record channel-scale lateral migration with no …