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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Effects Of Material Texture And Packing Density On The Interfacial Polarization Of Granular Soils, Hang Chen, Qifei Niu
Effects Of Material Texture And Packing Density On The Interfacial Polarization Of Granular Soils, Hang Chen, Qifei Niu
Geosciences Faculty Publications and Presentations
Many electrical and electromagnetic (EM) methods operate at MHz frequencies, at which the interfacial polarization occurring at the solid-liquid interface in geologic materials may dominate the electrical signals. To correctly interpret electrical/EM measurements, it is therefore critical to understand how the interfacial polarization influences the effective electrical conductivity and permittivity spectra of geologic materials. We have used pore-scale simulation to study the role of material texture and packing in interfacial polarization in water-saturated granular soils. Synthetic samples with varying material textures and packing densities are prepared with the discrete element method. The effective electrical conductivity and permittivity spectra of these …
Remote Sensing Of Soil Moisture Using S-Band Signals Of Opportunity: Model Development And Experimental Validation, Marvin Jesse, Benjamin Nold, James L. Garrison
Remote Sensing Of Soil Moisture Using S-Band Signals Of Opportunity: Model Development And Experimental Validation, Marvin Jesse, Benjamin Nold, James L. Garrison
The Summer Undergraduate Research Fellowship (SURF) Symposium
Root zone soil moisture (RZSM) is a vital aspect in meteorology, hydrology, and agriculture. There are currently some methods in passive and active remote sensing at L-band, but these methods are limited to a sensing depth of approximately 10 cm. Observing RZSM (water in the top meter of soil) will require lower frequencies, thus presenting significant difficulties for a spaceborne instrument, because of the required antenna size, the presence of radio-frequency interference (RFI), and competition for spectrum allocations (in the case of active radar). Bistatic radar using Signal of Opportunity (SoOp) (e.g. digital satellite transmitters) provides an opportunity for remote …
Spectral Induced Polarization (Sip) Response Of Biodegraded Oil In Porous Media, Gamal Z. Abdel Aal, Estella A. Atekwana
Spectral Induced Polarization (Sip) Response Of Biodegraded Oil In Porous Media, Gamal Z. Abdel Aal, Estella A. Atekwana
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Laboratory experiments were conducted to investigate the effect of different oil saturation (0.2- 0.8), wetting conditions (water-wet and oil-wet), and the addition of asphaltene on the spectral induced polarization (SIP) response of biodegraded and fresh crude oil in sand columns. In the water-wet case, no significant differences were observed for both the fresh and biodegraded oil and both displayed an increase in the magnitude of the phase (φ) and decrease in the magnitudes of the real (σ′) and imaginary (σ″) conductivity components with increasing oil saturation. In this instance the SIP response is most likely controlled by the conduction and …
A New Model For The Spectral Induced Polarization Signature Of Bacterial Growth In Porous Media, Andre Revil, Estella A. Atekwana, C. Zhang, Abderrahim Jardani, Schaun M. Smith
A New Model For The Spectral Induced Polarization Signature Of Bacterial Growth In Porous Media, Andre Revil, Estella A. Atekwana, C. Zhang, Abderrahim Jardani, Schaun M. Smith
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
The complex conductivity of porous materials and colloidal suspensions comprises two components: an in-phase conductivity associated with electromigration of the charge carriers and a quadrature conductivity associated with the reversible storage of the charges at some polarization length scales. We developed a quantitative model to investigate the frequency domain induced polarization response of suspensions of bacteria and bacteria growth in porous media. Induced polarization of bacteria (α polarization) is related to the properties of the electrical double layer of the bacteria. Surface conductivity and α polarization are due to the Stern layer of counterions occurring in a brush of polymers …
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. …
A Handheld Polarimeter For Aerosol Remote Sensing, James W. Frost, Fouad Nasraddine, J. Rodriguez, I. Andino, Brian Cairns
A Handheld Polarimeter For Aerosol Remote Sensing, James W. Frost, Fouad Nasraddine, J. Rodriguez, I. Andino, Brian Cairns
Publications and Research
In this paper we show how measurements made by a simple handheld polarimeter in conjunction with automated sunsky radiometers can be used to effectively constrain the real part of the complex refractive index of aerosols. We find that even measurements over a limited angular range near 90° scattering angle are sufficient for this purpose. We also note that because of the effect of surface reflectance on the observed degree of linear polarization (DOLP) it is sensible to select spectral bands for these measurements for which the surface is relatively dark and homogeneous (i.e. wavelengths shorter than 700 nm are to …
Mantle Deformation Beneath Southern Africa, Paul G. Silver, Stephen S. Gao, Kelly H. Liu, Kaapvaal Seismic Group
Mantle Deformation Beneath Southern Africa, Paul G. Silver, Stephen S. Gao, Kelly H. Liu, Kaapvaal Seismic Group
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Seismic anisotropy from the southern African mantle has been inferred from shear-wave splitting measured at 79 sites of the Southern African Seismic Experiment. These data provide the most dramatic support to date that Archean mantle deformation is preserved as fossil mantle anisotropy. Fast polarization directions systematically follow the trend of Archean structures and splitting delay times exhibit geologic control. The most anisotropic regions are Late-Archean in age (Zimbabwe craton, Limpopo belt, western Kaapvaal craton), with delay times reduced dramatically in off-craton regions to the southwest and Early-Archean regions to the southeast. While thin lithosphere can account for weak off-craton splitting, …
S K S Splitting Beneath Continental Rift Zones, Stephen S. Gao, Paul M. Davis, Kelly H. Liu, Philip D. Slack, Andrew W. Rigor, Yu A. Zorin, Valentina V. Mordvinova, Vladimir M. Kozhevnikov, Nikolai A. Logatchev
S K S Splitting Beneath Continental Rift Zones, Stephen S. Gao, Paul M. Davis, Kelly H. Liu, Philip D. Slack, Andrew W. Rigor, Yu A. Zorin, Valentina V. Mordvinova, Vladimir M. Kozhevnikov, Nikolai A. Logatchev
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
We present measurements of S K S splitting at 28 digital seismic stations and 35 analog stations in the Baikal rift zone, Siberia, and adjacent areas, and at 17 stations in the East African Rift in Kenya and compare them with previous measurements from the Rio Grande Rift of North America. Fast directions in the inner region of the Baikal rift zone are distributed in two orthogonal directions, NE and NW, approximately parallel and perpendicular to the NE strike of the rift. In the adjacent Siberian platform and northern Mongolian fold belt, only the rift-orthogonal fast direction is observed. In …
Hydrogen Overvoltage Of Cadmium Bismuth And Antimony Bismuth Alloys, Edwin W. Stevens
Hydrogen Overvoltage Of Cadmium Bismuth And Antimony Bismuth Alloys, Edwin W. Stevens
Bachelors Theses and Reports, 1928 - 1970
A method to measure hydrogen overvoltage was developed and checked with metals of known overvoltage. Alloys of bismuth and antimony and of bismuth and cadmium were prepared and their overvoltages determined.