Modeling Dielectric-Constant Values of Geologic Materials: An Aid to Ground-Penetrating Radar Data Collection and Interpretation

Ground-penetrating radar (GPR) is a near-surface geophysical imaging technique used for non-intrusive subsurface geologic and engineering investigations. Dielectric constant is a critical parameter for GPR surveys because it controls propagation velocity of electromagnetic waves through material, reflection coefficients across interfaces of different materials, and vertical and horizontal imaging resolution. Dielectric constant in rocks and sediments is primarily a function of mineralogy, porosity, pore fluids, frequency, geometries, and electrochemical interactions between rock components. Reported dielectric-constant values for sedimentary rocks provide general ranges of expected values, but these values may not adequately represent rocks in specific field conditions. Time-propagation mixing modeling, a forward-modeling technique, was performed and showed good correlation between modeled and measured dielectric constants of selected sandstones and limestones. Additional models were constructed to investigate the role of lithology and fluid saturation on dielectric constant and GPR response. Three modeled rock examples of variable mineralogy, porosity, and saturation illustrate that bulk dielectric constant, which generally ranges from 2 to 38 in the materials modeled, is primarily controlled by water saturation and, secondarily, by porosity and mineralogy, although these variables are interdependent. Without data stacking, differences in dielectric constant must be greater than 2 to produce reflections that can be recorded above background noise. For the examples modeled, saturation differences of less than 35% between layers produced reflection signals above background noise, but in completely dry material, normal mineralogic and porosity differences may not produce discernible reflections without stacking.   &nbsp

Modeling Dielectric-constant Values of Geologic Materials: An Aid to Ground-penetrating Radar Data Collection and Interpretation

Ground-penetrating radar (GPR) is a near-surface geophysical imaging technique used for non-intrusive subsurface geologic and engineering investigations. Dielectric constant is a critical parameter for GPR surveys because it controls propagation velocity of electromagnetic waves through material, reflection coefficients across interfaces of different materials, and vertical and horizontal imaging resolution. Dielectric constant in rocks and sediments is primarily a function of mineralogy, porosity, pore fluids, frequency, geometries, and electrochemical interactions between rock components. Reported dielectric-constant values for sedimentary rocks provide general ranges of expected values, but these values may not adequately represent rocks in specific field conditions. Time-propagation mixing modeling, a forward-modeling technique, was performed and showed good correlation between modeled and measured dielectric constants of selected sandstones and limestones. Additional models were constructed to investigate the role of lithology and fluid saturation on dielectric constant and GPR response. Three modeled rock examples of variable mineralogy, porosity, and saturation illustrate that bulk dielectric constant, which generally ranges from 2 to 38 in the materials modeled, is primarily controlled by water saturation and, secondarily, by porosity and mineralogy, although these variables are interdependent. Without data stacking, differences in dielectric constant must be greater than 2 to produce reflections that can be recorded above background noise. For the examples modeled, saturation differences of less than 35% between layers produced reflection signals above background noise, but in completely dry material, normal mineralogic and porosity differences may not produce discernible reflections without stacking

Modeling Dielectric-constant Values of Geologic Materials: An Aid to Ground-penetrating Radar Data Collection and Interpretation

Ground-penetrating radar (GPR) is a near-surface geophysical imaging technique used for non-intrusive subsurface geologic and engineering investigations. Dielectric constant is a critical parameter for GPR surveys because it controls propagation velocity of electromagnetic waves through material, reflection coefficients across interfaces of different materials, and vertical and horizontal imaging resolution. Dielectric constant in rocks and sediments is primarily a function of mineralogy, porosity, pore fluids, frequency, geometries, and electrochemical interactions between rock components. Reported dielectric-constant values for sedimentary rocks provide general ranges of expected values, but these values may not adequately represent rocks in specific field conditions. Time-propagation mixing modeling, a forward-modeling technique, was performed and showed good correlation between modeled and measured dielectric constants of selected sandstones and limestones. Additional models were constructed to investigate the role of lithology and fluid saturation on dielectric constant and GPR response. Three modeled rock examples of variable mineralogy, porosity, and saturation illustrate that bulk dielectric constant, which generally ranges from 2 to 38 in the materials modeled, is primarily controlled by water saturation and, secondarily, by porosity and mineralogy, although these variables are interdependent. Without data stacking, differences in dielectric constant must be greater than 2 to produce reflections that can be recorded above background noise. For the examples modeled, saturation differences of less than 35% between layers produced reflection signals above background noise, but in completely dry material, normal mineralogic and porosity differences may not produce discernible reflections without stacking

Corticomotor excitability during precision motor tasks

The aim of this preliminary study was to investigate motor cortex (cortical) excitability between a similar fine visuomotor task of varying difficulty. Ten healthy adults (three female, seven male; 20—45 years of age) participated in the study. Participants were instructed to perform a fine visuomotor task by statically abducting their first index finger against a force transducer which displayed the level of force (represented as a marker) on a computer monitor. This marker was to be maintained between two stationary bars, also displayed on the computer monitor. The level of difficulty was increased by amplifying the position of the marker, making the task more difficult to control. Cortical measures of motor evoked potential (MEP) and silent period (SP) duration in first dorsal interosseous (FDI) muscle were obtained using transcranial magnetic stimulation (TMS) while the participant maintained the ‘‘easy’’ or ‘‘difficult’’ static task. An 11.8% increase in MEP amplitude was observed when subjects undertook the ‘‘difficult’’ task, but no differences in MEP latency or SP duration. The results from this preliminary study suggest that cortical excitability increases reflect the demand required to perform tasks requiring greater precision with suggestions for further research discussed

CMB Constraints on Primordial non-Gaussianity from the Bispectrum (f_{NL}) and Trispectrum (g_{NL} and \tau_{NL}) and a New Consistency Test of Single-Field Inflation

We outline the expected constraints on non-Gaussianity from the cosmic microwave background (CMB) with current and future experiments, focusing on both the third (f_{NL}) and fourth-order (g_{NL} and \tau_{NL}) amplitudes of the local configuration or non-Gaussianity. The experimental focus is the skewness (two-to-one) and kurtosis (two-to-two and three-to-one) power spectra from weighted maps. In adition to a measurement of \tau_{NL} and g_{NL} with WMAP 5-year data, our study provides the first forecasts for future constraints on g_{NL}. We describe how these statistics can be corrected for the mask and cut-sky through a window function, bypassing the need to compute linear terms that were introduced for the previous-generation non-Gaussianity statistics, such as the skewness estimator. We discus the ratio A_{NL} = \tau_{NL}/(6f_{NL}/5)^2 as an additional test of single-field inflationary models and discuss the physical significance of each statistic. Using these estimators with WMAP 5-Year V+W-band data out to l_{max}=600 we constrain the cubic order non-Gaussianity parameters \tau_{NL}, and g_{NL} and find -7.4 < g_{NL}/10^5 < 8.2 and -0.6 < \tau_{NL}/10^4 < 3.3 improving the previous COBE-based limit on \tau_{NL} < 10^8 nearly four orders of magnitude with WMAP.Comment: 15 pages. 14 figure

Improving Resolution and Understanding Controls on GPR Response in Carbonate Strata: Implications for Attribute Analysis

This is the publisher's version, also available electronically from "http://mr.crossref.org".For more than a decade, environmental, engineering, groundwater, and shallow stratigraphic studies have demonstrated and advanced the usefulness of ground-penetrating radar (GPR) in lithified and unconsolidated sedimentary deposits (e.g., see Neal, 2004 and references therein). Despite the advances, important questions still remain on factors that control the actual appearance and characteristics of GPR reflections and diffractions in any given setting. ?? 2007 Society of Exploration Geophysicists

The Geology of Kansas—Arbuckle Group

Cambrian-Ordovician Arbuckle Group rocks in Kansas occur entirely in the subsurface. As is demonstrated throughout this paper, the historical and current understanding of the Arbuckle Group rocks in Kansas has in large part been dependent on petroleum-industry philosophies, practices, and trends. The widely accepted conceptual model of Arbuckle reservoirs as an unconformity play guided drilling and completion practices in which wells were drilled into the top of the Arbuckle with relatively short penetration (under 10 to 50 ft) deeper into the Arbuckle. This resulted in very little log or core data available from the Arbuckle interval. In addition, due to the early development (1917-1940) of the majority of Arbuckle reservoirs, log and geophysical data are not up to modern standards. Over the last few decades, deep penetrating wells have been drilled into the Arbuckle accompanied by full modern log suites and drill-stem tests. However, little corresponding core has been taken to calibrate the logs, and no detailed studies have been conducted to date on the more extensive, modern log data. Thus, data and detailed understanding of Arbuckle Group strata in Kansas are lacking relative to Arbuckle and age-equivalent strata from other areas in the United States, especially those where Arbuckle strata crop out. However, Arbuckle Group strata remain an important reservoir target in Kansas, and our understanding of the unit will increase with continued studies that incorporate modern data, techniques, and approaches

Supporting International Ab Initio Flight Students Through English Language Training

Effective communication between ab initio flight students and their instructors is critical for efficient flight training; additionally, clear radio communications between student pilots and air traffic controllers is imperative for smooth and incident-free airport operations. During the Fall 2019 semester, Embry-Riddle Aeronautical University (ERAU) at Daytona Beach implemented a new semi-intensive eight-week course to improve the communicative skills of its international students who speak English as a second language. This presentation describes the cross-campus and cross-departmental collaboration that took place to implement this new course. The stages that will be described include (a) the pre-screening of the students using ERAU’s online, remotely administered English for Flight Training Assessment (EFTA)™, a project initiated by Daytona Beach’s Applied Aviation Sciences Department and the Embry-Riddle Language Institute, and (b) the employment of a curriculum specifically designed for ab-initio flight students based on flight training materials created by the Aviation English Specialists at ERAU, Worldwide. The presenters will describe the teaching approaches used during the course and provide insights about the challenges faced and lessons learned throughout the eight weeks. The topic of aviation-familiarity for English language instructors will be discussed along with plans for improving the course. The audience will leave with insights about how to directly support international ab initio flight students and understand how ERAU’s approach to effective English language training can serve as an exemplar for the industry

Designing large, high-efficiency, high-numerical-aperture, transmissive meta-lenses for visible light

A metasurface lens (meta-lens) bends light using nanostructures on a flat surface. Macroscopic meta-lenses (mm- to cm-scale diameter) have been quite difficult to simulate and optimize, due to the large area, the lack of periodicity, and the billions of adjustable parameters. We describe a method for designing a large-area meta-lens that allows not only prediction of the efficiency and far-field, but also optimization of the shape and position of each individual nanostructure, with a computational cost that is almost independent of the lens size. As examples, we design three large NA = 0.94 meta-lenses: One with 79% predicted efficiency for yellow light, one with dichroic properties, and one broadband lens. All have a minimum feature size of 100nm.Engineering and Applied Science

4D Seismic to Image a Thin Carbonate Reservoir During a Miscible CO2 Flood: Hall-Gurney Field, Kansas, USA

This is the publisher's version, also available electronically from "http://mr.crossref.org".The movement of miscible CO2 injected into a shallow (900 m) thin (3.6-6m) carbonate reservoir was monitored using the high-resolution parallel progressive blanking (PPB) approach. The approach concentrated on repeatability during acquisition and processing, and use of amplitude envelope 4D horizon attributes. Comparison of production data and reservoir simulations to seismic images provided a measure of the effectiveness of time-lapse (TL) to detect weak anomalies associated with changes in fluid concentration. Specifically, the method aided in the analysis of high-resolution data to distinguish subtle seismic characteristics and associated trends related to depositional lithofacies and geometries and structural elements of this carbonate reservoir that impact fluid character and EOR efforts. Additional Publication Detail