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Articles 7981 - 8010 of 59552
Full-Text Articles in Earth Sciences
Advances In Machine Learning Aided Seismic Interpretation And Inversion For Subsurface Characterization, Tobi Micheal Ore
Advances In Machine Learning Aided Seismic Interpretation And Inversion For Subsurface Characterization, Tobi Micheal Ore
Graduate Theses, Dissertations, and Problem Reports (ETD)
Geophysical data are used to “remotely sense” the subsurface to illuminate structures, stratigraphy, and features that are of interest in the exploration for energy, suitable storage for carbon dioxide, geothermal development, and environmental considerations. The interpretations of these data typically are regarded as partially an art, as it depends on the experience of the interpreter. This is further exacerbated with the big data era as this data is large and takes several days, even longer, to manually interpret. To bridge this gap of speed and subjective bias, machine learning has been successfully applied to automate the geophysical interpretation process. This …
Geochemical Phase Associations Of Rare Earth Elements And Lithium In Black Shales Of The Usa: A Study In The Appalachian And Haynesville Basins, Shailee Bhattacharya
Geochemical Phase Associations Of Rare Earth Elements And Lithium In Black Shales Of The Usa: A Study In The Appalachian And Haynesville Basins, Shailee Bhattacharya
Graduate Theses, Dissertations, and Problem Reports (ETD)
Critical elements are an indispensable part of the clean energy transition. In the race for alternative energy technologies, lithium and rare earth elements have a proven record of being few of the most sought-after minerals. Limited availability of conventional mineral ores warrants a need to explore, understand and exploit unconventional sources of these elements. To that end, several studies have attempted to understand the rock and mineral assemblages of diverse geological systems. This doctoral thesis focuses on understanding the geochemistry of REE and Li in sedimentary environments, particularly black shale basins in the US. A suite of samples from natural …
A Gis Tool For Optimal Forage Species Selection, David B. Hannaway, Christopher Daly, Michael D. Halbleib, Linda Brewer, Sophie Baur, Chelsea Clark, Emilie Krecklow, Scott Bassett
A Gis Tool For Optimal Forage Species Selection, David B. Hannaway, Christopher Daly, Michael D. Halbleib, Linda Brewer, Sophie Baur, Chelsea Clark, Emilie Krecklow, Scott Bassett
IGC Proceedings (1977-2023)
To determine appropriate forage species for US ecoregions, geographic information technologies (GIS) are being used to create climatic and soil factor maps. Excel spreadsheets and RStudio are used to create response functions of forage species to minimum and maximum temperature, annual precipitation, soil pH, soil salinity, and salinity. National forage data and expert opinion will evaluate quantitative tolerances, seasonal yield profiles, and pollinator suitability. These maps and agronomic and livestock use information will be shared with forage specialists and farmers to provide alternatives for improved perenniality, increased diversity, and system circularity. Future work will include development and evaluation of climate …
Petrography Study Of The Recent Sediments In Hareer’S Region At Basrah Governorate - Southern Iraq, K J. Al-Sudani, B N. Albadran, A S Y Al-Hadadi, M H. Al-Jaberi, Jennifer R. Pournelle
Petrography Study Of The Recent Sediments In Hareer’S Region At Basrah Governorate - Southern Iraq, K J. Al-Sudani, B N. Albadran, A S Y Al-Hadadi, M H. Al-Jaberi, Jennifer R. Pournelle
Faculty Publications
Two sites of Hareer’s region is located in the southern part of Iraq, specifically in the northern Basrah Governorate. The sites are at a depth of 5 meters. The results of heavy mineral analysis showed that there are fifteen types include; Opaque grain (Iron Oxide), Chlorite, Muscovite mica, Biotite, Orthopyroxene, Clinopyroxene, Amphibole (Hornblende and Actinolite), Epidote, Garnet, Kyanite, Staurolite, Zircon, and Tourmaline. On the other hand the light minerals and the results of the mineral analyses revealed that they were primarily composed of rock fragments, with a variety of quartz minerals, feldspar minerals, evaporate minerals, clay-coated grains, and trace amounts …
Locating And Assessing Oregon Trail Ruts With Aerial Stereophotographs, Satellite Imagery And Lidar, P.R. Hanson, Robert Matthew Joeckel, L. M. Howard
Locating And Assessing Oregon Trail Ruts With Aerial Stereophotographs, Satellite Imagery And Lidar, P.R. Hanson, Robert Matthew Joeckel, L. M. Howard
Conservation and Survey Division: Faculty and Staff Publications
No abstract provided.
Integrating Remote Sensing With Ground-Based Observations To Quantify The Effects Of An Extreme Freeze Event On Black Mangroves (Avicennia Germinans) At The Landscape Scale, Melinda Martinez, Michael J. Osland, James B. Grace, Nicholas M. Enwright, Camille L. Stagg, Camille L. Stagg, Simen Kaalstad, Gordon H. Anderson, Elena A. Flores, Alejandro Fierro-Cabo
Integrating Remote Sensing With Ground-Based Observations To Quantify The Effects Of An Extreme Freeze Event On Black Mangroves (Avicennia Germinans) At The Landscape Scale, Melinda Martinez, Michael J. Osland, James B. Grace, Nicholas M. Enwright, Camille L. Stagg, Camille L. Stagg, Simen Kaalstad, Gordon H. Anderson, Elena A. Flores, Alejandro Fierro-Cabo
School of Earth, Environmental, & Marine Sciences Faculty Publications
Climate change is altering the frequency and intensity of extreme weather events. Quantifying ecosystem responses to extreme events at the landscape scale is critical for understanding and responding to climate-driven change but is constrained by limited data availability. Here, we integrated remote sensing with ground-based observations to quantify landscape-scale vegetation damage from an extreme climatic event. We used ground- and satellite-based black mangrove (Avicennia germinans) leaf damage data from the northern Gulf of Mexico (USA and Mexico) to examine the effects of an extreme freeze in a region where black mangroves are expanding their range. The February 2021 …
Exploring The Consistency Of Flow Regimes Within And Among Ecoregions Of The Southeastern United States, Frank Paul Braun Iv
Exploring The Consistency Of Flow Regimes Within And Among Ecoregions Of The Southeastern United States, Frank Paul Braun Iv
College of Graduate Studies: Theses & Dissertations
Human manipulation of river systems has long been a known contributor to the loss of freshwater biodiversity. By accounting for environmental causes of hydrologic variation among rivers, we can better understand how ecoregion mediates flow regimes and forecast species that may be at risk. Presumably, natural variation associated with ecoregion boundaries exerts strong influence on flow regimes, and may mediate relationships between other features (e.g., land use, dam operations) and hydrology. However, such between-ecoregion variation is poorly investigated, particularly at fine spatial and temporal scales. I characterized 10 hydrologic metrics, representing the five key dimensions of the flow regime (magnitude, …
Geoelectrical And Hydrochemical Characterization Of Submarine Groundwater Discharge In Florida Bay, Ifeanyi Emmanuel Eze
Geoelectrical And Hydrochemical Characterization Of Submarine Groundwater Discharge In Florida Bay, Ifeanyi Emmanuel Eze
College of Graduate Studies: Theses & Dissertations
Florida Bay, situated at the southern tip of Everglades National Park and underlain by the Miami Limestone formation, is an ecosystem of global significance. Over the past century, the bay has faced threats such as droughts, seagrass mortality, and hypersalinity. Despite various studies and management efforts, the dynamics of submarine groundwater discharge (SGD) in the region remain underexplored. Given that SGD plays a significant role in the chemical dynamics of coastal ecosystems, it warrants thorough investigation. This study aims to characterize the spatial and temporal patterns of SGD in Florida Bay by surveying three basins – Rankin, Whipray, and Rabbit …
Keynote Address And Meeting Program, Academy Editors
Keynote Address And Meeting Program, Academy Editors
Journal of the Arkansas Academy of Science
No abstract provided.
Instructions To Authors, Academy Editors
Instructions To Authors, Academy Editors
Journal of the Arkansas Academy of Science
No abstract provided.
Table Of Contents, Academy Editors
Table Of Contents, Academy Editors
Journal of the Arkansas Academy of Science
No abstract provided.
Business Meeting Report (Secretary's And Treasurer's Report), Academy Editors
Business Meeting Report (Secretary's And Treasurer's Report), Academy Editors
Journal of the Arkansas Academy of Science
No abstract provided.
Journal Acknowledgements And Editorial Board, Academy Editors
Journal Acknowledgements And Editorial Board, Academy Editors
Journal of the Arkansas Academy of Science
No abstract provided.
Academy Presidents And Institutional Members, Academy Editors
Academy Presidents And Institutional Members, Academy Editors
Journal of the Arkansas Academy of Science
No abstract provided.
Journal Of The Arkansas Academy Of Science Volume 78, Academy Editors
Journal Of The Arkansas Academy Of Science Volume 78, Academy Editors
Journal of the Arkansas Academy of Science
No abstract provided.
Mangroves Of The Warm Temperate Northwest Atlantic, Daniel A. Friess, Ena L. Suárez, Anna R. Armitage, Cheryl Doughty, Laura C. Feher, Ilka C. Feller, Alejandro Fierro, Kara R. Radabaugh, Lorae T. Simpson, William C. V Vervaeke, Carlos Zamora-Tovar
Mangroves Of The Warm Temperate Northwest Atlantic, Daniel A. Friess, Ena L. Suárez, Anna R. Armitage, Cheryl Doughty, Laura C. Feher, Ilka C. Feller, Alejandro Fierro, Kara R. Radabaugh, Lorae T. Simpson, William C. V Vervaeke, Carlos Zamora-Tovar
School of Earth, Environmental, & Marine Sciences Faculty Publications
The ‘Mangroves of the Warm Temperate Northwest Atlantic’ province is a regional ecosystem subgroup (level 4 unit of the IUCN Global Ecosystem Typology). It includes the marine ecoregions of Carolinian and Northern Gulf of Mexico. The biota is characterized by 3 species of mangroves: Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle, and 1 mangrove associate Conocarpus erectus, though not all species are equally distributed throughout the province. Mangroves in this province cross the USA and Mexico and are quite unique, as they exist at the latitudinal range limit of the mangrove ecosystem. The majority of mangroves in this province are …
Assessing Tax Revenue Implications Of Environmental Policy: A Case Study Of China’S Channel City Policy, Yongwen Yang, Juhee Lee
Assessing Tax Revenue Implications Of Environmental Policy: A Case Study Of China’S Channel City Policy, Yongwen Yang, Juhee Lee
School of Earth, Environmental, & Marine Sciences Faculty Publications
Recent studies suggest that while environmental policies yield positive environmental effects, they also incur costs for various entities. However, there is a gap in research regarding these policies’ financial impact from the government's perspective. To investigate the extent to which government tax revenue is affected by environmental policies, we employ the Difference-inDifferences (DID) method to estimate the impact of a regional air pollution control policy in China known as the Channel City Policy on the tax revenue of city governments. Our findings indicate that the Channel City Policy (CCP) enhances air quality by reducing PM2.5, SO2, and NOx concentrations by …
A Hybrid Algorithm To Dual Sparse Sampling Measurement In Time-Resolved Electromagnetic Near-Field Scanning, Yanming Zhang, Steven Gao, Lijun Jiang
A Hybrid Algorithm To Dual Sparse Sampling Measurement In Time-Resolved Electromagnetic Near-Field Scanning, Yanming Zhang, Steven Gao, Lijun Jiang
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Time-resolved electromagnetic near-field scanning is vital for antenna measurement and addressing complex electromagnetic interference and compatibility issues. However, the swift acquisition of high-resolution spatiotemporal data remains challenging due to physical constraints, such as moving the probe position and allowing sufficient time for sampling. This paper introduces a novel hybrid approach that combines Kriging for sparse spatial measurement, compressed sensing (CS) for sparse temporal sampling, and dynamic mode decomposition (DMD) for a comprehensive analysis of dual-sparse sampling electromagnetic near-field data. CS optimizes sparse sampling in the time domain, capitalizing on the inherent sparsity within electromagnetic radiated signals, resulting in reliable representation …
A Data-Driven Approach To Time-Domain Electromagnetic Modeling Based On Dynamic Mode Decomposition, Yanming Zhang, Steven Gao, Lijun Jiang
A Data-Driven Approach To Time-Domain Electromagnetic Modeling Based On Dynamic Mode Decomposition, Yanming Zhang, Steven Gao, Lijun Jiang
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
This paper presents a data-driven methodology that utilizes Dynamic Mode Decomposition (DMD) for the time-domain (TD) electromagnetic (EM) modeling of microwave devices. As an unsupervised machine learning technique, DMD leverages a limited set of unlabeled spatio-temporal electromagnetic (EM) data to determine DMD eigenvalues and eigenmodes. Then, the obtained DMD model reconstructs the dynamics as a series of exponential terms based on linear assumptions. The effectiveness of this approach is demonstrated through the TD EM modeling of photonic crystal waveguides. Comparative analysis with the finite-difference time-domain (FDTD) method shows that the DMD model not only achieves precise modeling but also facilitates …
Would Self-Supported Fracture Contribute To The Hydrocarbon Production In Shale Reservoir Besides Proppant-Supported Fracture, Y. Sun, G. Li, S. Zeng, J. Wu, J. Liu, M. Xu, C. Dai, Baojun Bai
Would Self-Supported Fracture Contribute To The Hydrocarbon Production In Shale Reservoir Besides Proppant-Supported Fracture, Y. Sun, G. Li, S. Zeng, J. Wu, J. Liu, M. Xu, C. Dai, Baojun Bai
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
During hydraulic fracturing in deep shale gas reservoirs, it is difficult to pump proppants long distances, and self-supported fractures are formed at the far and upper ends of the fractures. The self-supported fracture could hold the fracture space by its surface structure again fracture closure. However, it faces various aspects of impairment during shale gas reservoir development, which affect its conductivity. Among the impairment, long-term production results in a decline of bottom hole pressure, which will compact the fracture space, and self-supported fractures without proppant are more sensitive than those with proppant. In this paper, we conducted a series of …
An Unsupervised Learning Framework For Determining The Excitation Coefficients Using Near-Field Antenna Measurements, Yanming Zhang, Peifeng Ma, Steven Gao, Lijun Jiang
An Unsupervised Learning Framework For Determining The Excitation Coefficients Using Near-Field Antenna Measurements, Yanming Zhang, Peifeng Ma, Steven Gao, Lijun Jiang
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
This article presents a novel unsupervised learning framework based on multiscale dynamic mode decomposition for determining the excitation coefficients of antennas using time-domain near-field measurements. The proposed framework integrates temporal multiscale analysis to extract a joint distribution of frequency, damping factors, and spatial modes, enabling precise extraction of excitation frequencies, rising/falling edges, and phases without labeled data. We validate the effectiveness of the proposed approach through two examples involving on-off keying modulation and a phase-shift dipole antenna. It is found that the proposed method performs well in handling nonstationary excitation signals and proves particularly advantageous for calibrating tunable antenna systems. …
Diatom Productivity And Nutrient Dynamics In The Ross Sea, Antarctica During Warm Events In The Neogene, Marialena Christopoulou
Diatom Productivity And Nutrient Dynamics In The Ross Sea, Antarctica During Warm Events In The Neogene, Marialena Christopoulou
Graduate Research Theses & Dissertations
Increased melting of the Antarctic Ice Sheet (AIS) in recent decades, has had a significant impact on many aspects of the global ocean. Models indicate that by the end of the 21st century atmospheric carbon dioxide (CO2) concentrations may exceed 500 ppm, and the average global temperature will likely warm by more than 2°C. However, data that provide model constraints on potential feedbacks in ice-ocean-atmosphere system are limited by short-timescales (e.g., decadal- to centennial-scale) and incomplete spatial coverage. In particular, little is known about the impacts of future warming and widespread melting of AIS on marine biological productivity, silicate weathering …
Hunting Types In North American Eocene And Oligocene Carnivores And Implications For Nimravid Extinction, Miguel Andres Castellanos
Hunting Types In North American Eocene And Oligocene Carnivores And Implications For Nimravid Extinction, Miguel Andres Castellanos
Graduate Research Theses & Dissertations
The late Eocene and Oligocene is traditionally seen as a time of great climactic shift, with open habitats beginning to appear and forests receding. This time period saw both the diversification and subsequent extinction of North American nimravids. The causes of the extinction of this early sabertooth group in the Arikareean remain unclear. One possibility for their decline is that nimravids were competitively disadvantaged in open habitats relative to contemporary, possibly more cursorial caniform predators. Here I analyze and compare the hunting styles of Eocene and Oligocene predators in correlation with their ecological implications via discriminant function analysis of the …
Tracing Past Climate Signals Through Multi-Proxy Analysis: Insights From Sedimentary Plant Wax Hydrogen Isotope Data And Long-Term Hydroclimate Records In Estonia, Mariliis Eensalu
Tracing Past Climate Signals Through Multi-Proxy Analysis: Insights From Sedimentary Plant Wax Hydrogen Isotope Data And Long-Term Hydroclimate Records In Estonia, Mariliis Eensalu
Graduate Research Theses & Dissertations
In light of the rising global temperatures, there is an increasing need to understand the potential shifts in hydroclimate. Past climate reconstructions offer a glimpse into the possible temperature-moisture dynamics by providing quantitative constraints for hydroclimate variability under different temperature conditions, which can ultimately aid in decreasing the uncertainty in future climate projections. The research presented in this dissertation focuses on utilizing various proxies to reconstruct past hydroclimate conditions, particularly in the Baltic region, with a specific emphasis on Estonia. The second and third chapter aim to improve the understanding of sedimentary plant wax hydrogen isotope (δ2H) data by first …
Temporal Microplastic Concentration Fluctuations Within An Agricultural Creek And Groundwater In Relation To Farming Practices, Jennifer Abel
Temporal Microplastic Concentration Fluctuations Within An Agricultural Creek And Groundwater In Relation To Farming Practices, Jennifer Abel
Graduate Research Theses & Dissertations
Microplastics (MPs) in agriculture have been well-documented. Agrochemicals, organic fertilizers, and farming equipment all contribute plastic to agricultural soils, groundwater, and surface water and are utilized in different capacities throughout the year. It is unknown how the specific utilization of these products affects the concentration of MPs being input into the environment. Previous research has been primarily related to detection and transport of MPs in soils, groundwater, and surface water. I am unaware of any studies that have taken into consideration farming practices and seasons, and how they may affect any fluctuations in MP concentrations. Water samples (20 L) were …
Alfred Russel Wallace Notes 29. Extraterrestrial Entertainment: Are We Being Monitored By Alien Beings?, Charles H. Smith
Alfred Russel Wallace Notes 29. Extraterrestrial Entertainment: Are We Being Monitored By Alien Beings?, Charles H. Smith
Faculty/Staff Personal Papers
Alfred Russel Wallace (1823−1913) was an early advocate for the rational assessment of likelihood of extraterrestrial life. Current efforts to evaluate the situation have ranged from the heavily self-indulgent to the more objective, and it is still often difficult to decide just how much of the information we are receiving on the subject is dependable. An attempt is made here to cut through the haze and reduce the matter to elementals.
Nitrogen Fertilizer Placement And Rate Impacts Sunflower Seed Yield, Oil And Protein Content, Rojina Kafle
Nitrogen Fertilizer Placement And Rate Impacts Sunflower Seed Yield, Oil And Protein Content, Rojina Kafle
Electronic Theses and Dissertations
South Dakota accounts for about 36% of the total US commercial sunflower production and nitrogen is a major input. Costs related to N fertilizer demand economically optimum N rates. This study investigated the impact of the N fertilizer placement method (broadcast vs band) and rate (0, 28, 56, 84, 112, 140 kg N ha-1) on leaf chlorophyll content, head diameter, seed yield, seed oil, and protein concentration of three sunflower hybrids in 2022 and 2023. The experiment was conducted at Brookings (eastern SD- conventional till, 66 cm rainfall) using an oil-type hybrid and at central SD sites (no-till, 57 cm …
Characterizing Mountainous Bedrock Groundwater Systems Across Gradients In Topography And Lithology In Western Montana, David L. Baude
Characterizing Mountainous Bedrock Groundwater Systems Across Gradients In Topography And Lithology In Western Montana, David L. Baude
Graduate Student Theses, Dissertations, & Professional Papers
Mountain aquifer groundwater systems remain one of the least understood hydrologic systems in upland hydrology. In this study, we aim to characterize bedrock groundwater system dynamics and bedrock-saprolite interactions across a variety of landscape positions and lithology. We investigate groundwater hydraulics, recharge temperature and elevation, residence times, and bedrock recharge rates across two mountainous headwater catchments in west central Montana. We used a suite of environmental tracers (3H, CFCs, SF6, and 4He) and residence time distribution models to estimate groundwater mean residence times over a range of timescales from decades to millennia. Tracers were sampled …
Modeling Apparent Pb Loss In Zircon U-Pb Geochronology, Glenn R. Sharman, Matthew A. Malkowski
Modeling Apparent Pb Loss In Zircon U-Pb Geochronology, Glenn R. Sharman, Matthew A. Malkowski
Geosciences Faculty Publications and Presentations
The loss of radiogenic Pb from zircon is known to be a major factor that can cause inaccuracy in the U–Pb geochronological system; hence, there is a need to better characterize the distribution of Pb loss in natural samples. Treatment of zircon by chemical abrasion (CA) has become standard practice in isotope dilution–thermal ionization mass spectrometry (ID-TIMS), but CA is much less commonly employed prior to in situ analysis via laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) or secondary ionization mass spectrometry (SIMS). Differentiating the effects of low levels of Pb loss in Phanerozoic zircon with relatively low-precision in situ U–Pb …
A Bayesian Inversion For Emissions And Export Productivity Across The End-Cretaceous Boundary, Alexander A. Cox
A Bayesian Inversion For Emissions And Export Productivity Across The End-Cretaceous Boundary, Alexander A. Cox
Dartmouth College Master’s Theses
The end-Cretaceous mass extinction was marked by both the Chicxulub impact and the ongoing emplacement of the Deccan Traps flood basalt province. Both of these events perturbed the environment by the emission of climate-active volatiles, primarily CO2 and SO2. To understand the mechanism of extinction, we must disentangle the timing, duration, and intensity of volcanic and meteoritic environmental forcings. In this thesis, we used a parallel Markov chain Monte Carlo approach to invert for the aforementioned volatile emissions, export productivity, and remineralization from 67 to 65 million years ago using the LOSCAR (Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir) model. The parallel …