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Articles 1 - 16 of 16
Full-Text Articles in Physical Sciences and Mathematics
Subsurface Mimo: A Beamforming Design In Internet Of Underground Things For Digital Agriculture Applications, Abdul Salam
Subsurface Mimo: A Beamforming Design In Internet Of Underground Things For Digital Agriculture Applications, Abdul Salam
Faculty Publications
In underground (UG) multiple-input and multiple-output (MIMO), the transmit beamforming is used to focus energy in the desired direction. There are three different paths in the underground soil medium through which the waves propagates to reach at the receiver. When the UG receiver receives a desired data stream only from the desired path, then the UG MIMO channel becomes three path (lateral, direct, and reflected) interference channel. Accordingly, the capacity region of the UG MIMO three path interference channel and degrees of freedom (multiplexing gain of this MIMO channel requires careful modeling). Therefore, expressions are required for the degree of …
Analyzing The Efficiency Of Horizontal Photovoltaic Cells In Various Climate Regions, Parker A. Hines, Torrey J. Wagner, Clay M. Koschnick, Steven J. Schuldt
Analyzing The Efficiency Of Horizontal Photovoltaic Cells In Various Climate Regions, Parker A. Hines, Torrey J. Wagner, Clay M. Koschnick, Steven J. Schuldt
Faculty Publications
This research presents the development of linear regression models to predict horizontal photovoltaic power output. We collected a dataset from 14 global Department of Defense (DoD) installations over a timeframe of one year using an experimental apparatus, resulting in 24,179 usable data points. We developed a linear model to predict power output, which incorporated site-specific weather and geographical characteristics, along with Köppen-Geiger climate classifications in order to determine the effect of adding climate to the model. After performing a Wald test between the full model and a reduced model without Köppen-Geiger climate variables, it was determined that including Köppen-Geiger climate …
Structural Control Of Mesic Vegetation Communities Within The Owl And Bear Creek Watersheds, Fort Hood Military Installation, Texas, Melinda S. Faulkner, Matthew Mcbroom, Kenneth W. Farrish, Kevin Stafford
Structural Control Of Mesic Vegetation Communities Within The Owl And Bear Creek Watersheds, Fort Hood Military Installation, Texas, Melinda S. Faulkner, Matthew Mcbroom, Kenneth W. Farrish, Kevin Stafford
Faculty Publications
The Fort Hood Military Installation is a karst landscape, dominated by Lower Cretaceous carbonates of the Trinity and Fredericksburg groups. The study area is the northeastern peninsula known as the Owl Mountain Province, utilized by the U.S. Army for troop maneuvers and training. The geomorphic evolution of the province has been controlled by the structural development of incised canyons in the Owl and Bear creek watersheds, following the deformational trend of the Balcones/Ouachita fault system and the transverse Belton High-Central Texas Reef Trend. These trends control cave development in the subsurface, karst manifestations at the surface, joints in outcrop, stream …
Statistical Viability Analysis Of United States Air Force Estimating Cost Factor For Sustainable Construction, Philip A. Ramsey, Diedrich Prigge, Torrey J. Wagner, Alfred E. Thal Jr.
Statistical Viability Analysis Of United States Air Force Estimating Cost Factor For Sustainable Construction, Philip A. Ramsey, Diedrich Prigge, Torrey J. Wagner, Alfred E. Thal Jr.
Faculty Publications
Varying legislation and executive orders coupled with needs for energy resiliency have led the United States Air Force (USAF) to pursue sustainable construction. However, the limited understanding of initial costs to implement these changes have contributed to poor project cost estimating, resulting in 62 percent of USAF projects experiencing more than 5 percent cost growth. After reviewing 1628 USAF Military Construction (MILCON) construction projects in 922 category codes (CATCODEs), a twotailed t-test for populations with unequal variance was accomplished on the final normalized contract cost for 340 projects in 16 CATCODEs executed between 2002 and 2017. This analysis provides a …
Using Wind And Hydro Power To Sustain The Off-Grid Power Supply For A 50' Cruising Sailboat, Keisha Meyer, Torrey J. Wagner, Jada Williams
Using Wind And Hydro Power To Sustain The Off-Grid Power Supply For A 50' Cruising Sailboat, Keisha Meyer, Torrey J. Wagner, Jada Williams
Faculty Publications
Cruising sailboats operate with a power requirement modest enough to operate mostly or completely on renewable energy technology sources. Cruisers without renewable energy systems use the vessel’s diesel engine to charge the boat’s batteries; if the systems are operated at anchor, this dramatically decreases the time before the engine needs major overhaul. System users estimate a diesel engine can run approximately 8,000 hours underway before needing major overhaul, whereas operating 500 hours at anchor produces similar wear and tear on engine pistons. Although renewable energy systems have a high initial capital cost, these systems can provide the vessel’s electrical system …
Urban Underground Infrastructure Monitoring Iot: The Path Loss Analysis, Abdul Salam, Syed Shah
Urban Underground Infrastructure Monitoring Iot: The Path Loss Analysis, Abdul Salam, Syed Shah
Faculty Publications
The extra quantities of wastewater entering the pipes can cause backups that result in sanitary sewer overflows. Urban underground infrastructure monitoring is important for controlling the flow of extraneous water into the pipelines. By combining the wireless underground communications and sensor solutions, the urban underground IoT applications such as real time wastewater and storm water overflow monitoring can be developed. In this paper, the path loss analysis of wireless underground communications in urban underground IoT for wastewater monitoring has been presented. It has been shown that the communication range of up to 4 kilometers can be achieved from an underground …
An Underground Radio Wave Propagation Prediction Model For Digital Agriculture, Abdul Salam
An Underground Radio Wave Propagation Prediction Model For Digital Agriculture, Abdul Salam
Faculty Publications
Underground sensing and propagation of Signals in the Soil (SitS) medium is an electromagnetic issue. The path loss prediction with higher accuracy is an open research subject in digital agriculture monitoring applications for sensing and communications. The statistical data are predominantly derived from site-specific empirical measurements, which is considered an impediment to universal application. Nevertheless, in the existing literature, statistical approaches have been applied to the SitS channel modeling, where impulse response analysis and the Friis open space transmission formula are employed as the channel modeling tool in different soil types under varying soil moisture conditions at diverse communication distances …
Austere Location Wind Turbine Energy System Analysis, Lukas Cowen, Douglas S. Dudis, Torrey J. Wagner
Austere Location Wind Turbine Energy System Analysis, Lukas Cowen, Douglas S. Dudis, Torrey J. Wagner
Faculty Publications
One promising technology to combat an energy shortage in austere locations is wind energy. In combination with battery storage and generator backup, we explore the feasibility of using a hybrid energy system to reduce the volume of diesel fuel required. Modeling the energy demands in austere locations will enable missions in remote settings to optimize their energy costs, increased their energy resiliency and assure their supply. For a modeled time-series energy requirement that varied between 2.4 MW and 5.1 MW, the optimal wind system size was 9.9 MW of installed wind power paired with a 741 kWh battery. Assuming an …
36% Reduction In Fuel Resupply Using A Hybrid Generator & Battery System For An Austere Location, David J. Chester [*], Torrey J. Wagner, Douglas S. Dudis
36% Reduction In Fuel Resupply Using A Hybrid Generator & Battery System For An Austere Location, David J. Chester [*], Torrey J. Wagner, Douglas S. Dudis
Faculty Publications
The DOD energy policy is to increase energy security resiliency, and mitigate costs in the use and management of energy[1] Forward operating bases (FOBs) are remote, austere base camps that support an operationally defined mission with a limited or no ability to draw from an energy grid and have historically relied on diesel-powered generators for the primary production of energy.[2] Generators are sized to meet a theoretical peak demand, but steady state loads are far below this peak, resulting in under-loaded generators.[3] Under-loaded diesel generators decrease efficiency and increase the need for maintenance, affecting the lifespan of …
A Theoretical Model Of Underground Dipole Antennas For Communications In Internet Of Underground Things, Abdul Salam, Mehmet C. Vuran, Xin Dong, Christos Argyropoulos, Suat Irmak
A Theoretical Model Of Underground Dipole Antennas For Communications In Internet Of Underground Things, Abdul Salam, Mehmet C. Vuran, Xin Dong, Christos Argyropoulos, Suat Irmak
Faculty Publications
The realization of Internet of Underground Things (IOUT) relies on the establishment of reliable communication links, where the antenna becomes a major design component due to the significant impacts of soil. In this paper, a theoretical model is developed to capture the impacts of change of soil moisture on the return loss, resonant frequency, and bandwidth of a buried dipole antenna. Experiments are conducted in silty clay loam, sandy, and silt loam soil, to characterize the effects of soil, in an indoor testbed and field testbeds. It is shown that at subsurface burial depths (0.1-0.4m), change in soil moisture impacts …
Deep Sea Biofilms, Historic Shipwreck Preservation And The Deepwater Horizon Spill, Rachel L. Mugge, Melissa L. Brock, Jennifer L. Salerno, Melanie Damour, Robert A. Church, Jason Lee, Leila J. Hamdan
Deep Sea Biofilms, Historic Shipwreck Preservation And The Deepwater Horizon Spill, Rachel L. Mugge, Melissa L. Brock, Jennifer L. Salerno, Melanie Damour, Robert A. Church, Jason Lee, Leila J. Hamdan
Faculty Publications
Exposure to oil from the Deepwater Horizon spill may have lasting impacts on preservation of historic shipwrecks in the Gulf of Mexico. Submerged steel structures, including shipwrecks, serve as artificial reefs and become hotspots of biodiversity in the deep-sea. Marine biofilms on submerged structures support settlement of micro- and macrobiota and may enhance and protect against corrosion. Disruptions in the local environment, including oil spills, may impact the role that biofilms play in reef preservation. To determine how the Deepwater Horizon spill potentially impacted shipwreck biofilms and the functional roles of the biofilm microbiome, experiments containing carbon steels disks (CSDs) …
A Variable Nonlinear Splitting Algorithm For Reaction Diffusion Systems With Self- And Cross-Diffusion, Matthew Beauregard, Joshua L. Padgett
A Variable Nonlinear Splitting Algorithm For Reaction Diffusion Systems With Self- And Cross-Diffusion, Matthew Beauregard, Joshua L. Padgett
Faculty Publications
Self- and cross-diffusion are important nonlinear spatial derivative terms that are included into biological models of predator-prey interactions. Self-diffusion models overcrowding effects, while cross-diffusion incorporates the response of one species in light of the concentration of another. In this paper, a novel nonlinear operator splitting method is presented that directly incorporates both self- and cross-diffusion into a computational efficient design. The numerical analysis guarantees the accuracy and demonstrates appropriate criteria for stability. Numerical experiments display its efficiency and accuracy
Effectiveness Of Plant Species For Removing Atmospheric Ammonia, Marife B. Anunciado, Sheryll B. Jerez, Hans Williams, Joey Bray, Dean W. Coble, Rena Saito
Effectiveness Of Plant Species For Removing Atmospheric Ammonia, Marife B. Anunciado, Sheryll B. Jerez, Hans Williams, Joey Bray, Dean W. Coble, Rena Saito
Faculty Publications
Six plant species of Yaupon, Eastern red cedar, American holly, Arizona cypress, Arborvitae and Roughleaf dogwood were utilized to determine their effectiveness in the removal of atmospheric ammonia. All species were exposed to three ammonia levels (1, 5 and 10 ppm) in an environmental chamber. Foliar ammonia content was quantified using an enzymatic technique. The effects of exposure to ammonia on the physiological responses (e.g. photosynthetic activity, stomatal conductance, and transpiration rate) of plants in ambient condition were also determined using an open design photosynthetic gas exchange system. Foliar ammonia content was significantly different among the six plant species (p<0.0001) with Eastern red cedar exhibiting the highest content. The physiological responses differed significantly depending on the plant species and the ammonia treatment level. The photosynthetic response of plants to the presence of ammonia was mixed. At low exposure level, all species except Arborvitae had decreased photosynthetic activity, reducing by as much as 44.5% for Yaupon. At the highest concentration, however, Yaupon’s photosynthetic activity improved by about 10%. Exposure to ammonia caused increased stomatal conductance and transpiration rate on American holly and Arizona cypress, making them more susceptible to water loss.
A Student Led Investigation Of The Landscape Dynamics Of Campus Recycling, Brandon Mcbride, Cheryl L. Scott, David L. Kulhavy, I-Kuai Hung, Daniel Unger
A Student Led Investigation Of The Landscape Dynamics Of Campus Recycling, Brandon Mcbride, Cheryl L. Scott, David L. Kulhavy, I-Kuai Hung, Daniel Unger
Faculty Publications
Two senior undergraduate students within the environmental science division at Stephen F. Austin State University (SFASU) quantitatively diagnosed the environmental, ecological, and socioeconomic dynamics involved in plastic recycling. This study incorporated actively collecting recycled plastic bottles on campus to produce an enumerated analysis of recycling on campus; and to gain an understanding of the socioeconomics of recycling via an anonymous survey used to determine the recycling knowledgebase of natural resource students at SFASU. Undergraduate students, via their incorporation into a campus wide environmental site assessment of recycling plastic bottles, were able to apply their classroom knowledge to a real-world environmental …
Move It Or Lose It: Interspecific Variation In Risk Response Of Pond-Breeding Anurans, Philip Matich, Christopher M. Schalk
Move It Or Lose It: Interspecific Variation In Risk Response Of Pond-Breeding Anurans, Philip Matich, Christopher M. Schalk
Faculty Publications
Changes in behavior are often the proximate response of animals to human disturbance, with variability in tolerance levels leading some species to exhibit striking shifts in life history, fitness, and/or survival. Thus, elucidating the effects of disturbance on animal behavior, and how this varies among taxonomically similar species with inherently different behaviors and life histories is of value for management and conservation. We evaluated the risk response of three anuran species—southern leopard frog (Lithobates sphenocephalus), Blanchard’s cricket frog (Acris blanchardi), and green tree frog (Hyla cinerea)—to determine how differences in microhabitat use (arboreal vs …
The Search For Microbial Martian Life And American Buddhist Ethics, Daniel S. Capper
The Search For Microbial Martian Life And American Buddhist Ethics, Daniel S. Capper
Faculty Publications
Multiple searches hunt for extraterrestrial life, yet the ethics of such searches in terms of fossil and possible extant life on Mars have not been sufficiently delineated. In response, in this essay I propose a tripartite ethic for searches for microbial Martian life that consists of default nonharm toward potential living beings, default nonharm to the habitats of potential living beings, but also responsible, restrained scientific harvesting of some microbes in limited transgression of these default nonharm modes. Although this multifaceted ethic remains secular and hence adaptable to space research settings, it arises from both a qualitative analysis of authoritative …