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Articles 14191 - 14220 of 59516

Full-Text Articles in Earth Sciences

Analysis On Spatio-Temporal Evolution Law Of Freezing Temperature Field In Eastern Shaft Of Qinan Coal Mine, Huang Shiqing, Rong Chuanxin, Long Wei, Ma Haochen, He Junzhen Aug 2022

Analysis On Spatio-Temporal Evolution Law Of Freezing Temperature Field In Eastern Shaft Of Qinan Coal Mine, Huang Shiqing, Rong Chuanxin, Long Wei, Ma Haochen, He Junzhen

Coal Geology & Exploration

Three numerical calculation models of the freezing temperature fields with different soil nature and different burial depths, i.e. the calcareous clay horizon with the burial depth of 218 m, the fine sand horizon with the burial depth of 225 m and the sandy clay horizon with the burial depth of 259 m, were established respectively using the finite element software COMSOL Multiphysics based on the actual forming locations of freezing holes, with the engineering background of using the freezing method in shaft sinking for the eastern air shaft of Qinan Coal Mine Anhui Province and the study object of the …


Abnormal Response Characteristic Simulation During Transient Electromagnetic Detection In Mine Borehole, Zhang Jun Aug 2022

Abnormal Response Characteristic Simulation During Transient Electromagnetic Detection In Mine Borehole, Zhang Jun

Coal Geology & Exploration

Conventional mine transient electromagnetic advance detection method is greatly influenced by the condition outside of the mine, which leads to the inaccurate location in anomalous body detection. In order to solve this problem, an advance detection method for measuring the three-component signals of the transient electromagnetic field in the down-hole borehole was proposed to carry out numerical simulation for the abnormal response characteristics from the different locations of the plane where the receiving coil is located and the different orientations of the anomalous body. The principle of borehole transient electromagnetic detection was analyzed, and the test design and construction design …


Study Of Advance Elaborate Detection With Transient Electromagnetic Method For Mine With Closed Poor Boreholes, Huang Zhongzheng, Jiang Guoqing, Wang Jun, Cheng Jiulong, Ma Zhi, Tian Chuxiao, Xin Chengtao Aug 2022

Study Of Advance Elaborate Detection With Transient Electromagnetic Method For Mine With Closed Poor Boreholes, Huang Zhongzheng, Jiang Guoqing, Wang Jun, Cheng Jiulong, Ma Zhi, Tian Chuxiao, Xin Chengtao

Coal Geology & Exploration

Closed poor boreholes connect aquifers at some degree to form well concealed water diversion channels, which poses a water hazard threat on either tunneling or working bench recovery. In order to discuss the effectiveness of using the transient electromagnetic method in the advance detection of closed poor boreholes for the mine, the 3D geologic-geophysical model of the closed poor boreholes in front of the tunneling working bench was established based on the full-space transient electromagnetic theory to simulate and study the response characteristics of the full-space transient electromagnetic field in the influence area model of closed poor boreholes. As indicated …


Experimental Study On Nondestructive Testing Of Anchor Cable In Pumped Storage Power Station, Yan Liangping, Zhou Liming, Cui Botao, Wang Bolin, Lu Jiangang Aug 2022

Experimental Study On Nondestructive Testing Of Anchor Cable In Pumped Storage Power Station, Yan Liangping, Zhou Liming, Cui Botao, Wang Bolin, Lu Jiangang

Coal Geology & Exploration

In order to demonstrate the effect of elastic wave reflection method, the nondestructive testing test of anchor cables was carried out at the bank slope of Fukang Pumped Storage Power Station in Xinjiang. On the basis of the basic theory of elastic wave reflection method, the anchor cable sensor is embedded, and the data acquisition, signal excitation position and wave velocity of anchor body in the process of nondestructive testing of anchor cable are systematically studied. The following results are obtained: When the receiving sensor position is fixed and the excitation part is the steel strand where the receiving sensor …


Development And Application Of A Retractable Slip Overshot In Underground Coal Mines, Wu Tao Aug 2022

Development And Application Of A Retractable Slip Overshot In Underground Coal Mines, Wu Tao

Coal Geology & Exploration

The stuck and buried drills in underground coal mines often lead to accidents of broken drill pipes in the holes. At present, the success rate of the commonly used fishing methods of male and female fishing tap buckle is low, which not only consumes a lot of manpower and material resources, but also affects the production progress of coal mining. Based on this, a retractable slip overshot with the structural design of the cooperation between the slips and the outer cylinder through the wedge-shaped spiral surface has been proposed, which converts the pull-out force of the drill rod into a …


The Art Of Landslides: How Stochastic Mass Wasting Shapes Topography And Influences Landscape Dynamics, Benjamin Campforts, Charles Shobe, Irina Overeem, Gregory Tucker Aug 2022

The Art Of Landslides: How Stochastic Mass Wasting Shapes Topography And Influences Landscape Dynamics, Benjamin Campforts, Charles Shobe, Irina Overeem, Gregory Tucker

Faculty & Staff Scholarship

Bedrock landslides shape topography and mobilize large volumes of sediment. Yet, interactions between landslide-produced sediment and fluvial systems that together govern large-scale landscape evolution are not well understood. To explain morphological patterns observed in steep, landslide-prone terrain, we explicitly model stochastic landsliding and associated sediment dynamics. The model accounts for several common landscape features such as slope frequency distributions, which include values in excess of regional stability limits, quasi-planar hillslopes decorated with straight, closely spaced channel-like features, and accumulation of sediment in valley networks rather than on hillslopes. Stochastic landsliding strongly affects the magnitude and timing of sediment supply to …


Seasonality Of Precipitation In The Southwestern United States During The Late Pleistocene Inferred From Stable Isotopes In Herbivore Tooth Enamel, Matthew J. Kohn, Kathleen B. Springer, Jeffrey S. Pigati, Linda M. Reynard, Amanda E. Drewicz, Justin Crevier, Eric Scott Aug 2022

Seasonality Of Precipitation In The Southwestern United States During The Late Pleistocene Inferred From Stable Isotopes In Herbivore Tooth Enamel, Matthew J. Kohn, Kathleen B. Springer, Jeffrey S. Pigati, Linda M. Reynard, Amanda E. Drewicz, Justin Crevier, Eric Scott

United States Geological Survey: Staff Publications

The late Pleistocene was a climatically dynamic period, with abrupt shifts between cool-wet and warmdry conditions. Increased effective precipitation supported large pluvial lakes and long-lived spring ecosystems in valleys and basins throughout the western and southwestern U.S., but the source and seasonality of the increased precipitation are debated. Increases in the proportions of C4/(C4+ C3) grasses in the diets of large grazers have been ascribed both to increases in summer precipitation and lower atmospheric CO2 levels. Here we present stable carbon and oxygen isotope data from tooth enamel of late Pleistocene herbivores recovered …


Microplastics In The Marine Environment And Deep-Sea Sediment Contamination: A Review, Elizabeth Sangiolo Aug 2022

Microplastics In The Marine Environment And Deep-Sea Sediment Contamination: A Review, Elizabeth Sangiolo

Honors Program Theses and Projects

This review discusses what microplastics are and how they are continuously impacting the marine environment, and ultimately, human life. Plastic has been the number one used material for decades for industrial and recreational purposes. Its cost effectiveness, durability, and lightness are what manufacturers and consumers desire most, making plastic the most abundant pollutant in the world. Understanding how plastic pollution is broken down into microplastics and how these fragmented pieces of waste are classified can help researchers identify ways to prevent the additional input of microplastics in the marine environment. These microscopic particles of debris have been sampled from deep-sea …


Collateral Damage: Anticoagulant Rodenticides Pose Threats To California Condors, Garth Herring, Collin A. Eagles-Smith, Rachel Wolstenholme, Alacia Welch, Chris West, Barnett A. Rattner Aug 2022

Collateral Damage: Anticoagulant Rodenticides Pose Threats To California Condors, Garth Herring, Collin A. Eagles-Smith, Rachel Wolstenholme, Alacia Welch, Chris West, Barnett A. Rattner

United States Geological Survey: Staff Publications

Anticoagulant rodenticides (ARs) are widespread environmental contaminants that pose risks to scavenging birds because they routinely occur within their prey and can cause secondary poisoning. However, little is known about AR exposure in one of the rarest avian scavengers in the world, the California condor (Gymnogyps californianus). We assessed AR exposure in California condors and surrogate turkey vultures (Cathartes aura) to gauge potential hazard to a proposed future condor flock by determining how application rate and environmental factors influence exposure. Additionally, we examined whether ARs might be correlated with prolonged blood clotting time and potential mortality …


Mgrre_Thinsections_Mgrre-108_5, Mgrre Aug 2022

Mgrre_Thinsections_Mgrre-108_5, Mgrre

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Mgrre_Thinsections_Mgrre-108_3, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_1, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_6, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_8, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_7, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_9, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_11, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_12, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_13, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_14, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_15, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_16, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_17, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_18, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_4, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_2, Mgrre Aug 2022

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Mgrre_Thinsections_Mgrre-108_10, Mgrre Aug 2022

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Spatial Analysis Of Burn Severity And Streamflow Response In The Western Conus, Will Brendan Long Aug 2022

Spatial Analysis Of Burn Severity And Streamflow Response In The Western Conus, Will Brendan Long

Dissertations and Theses

Wildfire increases the magnitude of runoff in catchments, which can lead to the degradation of ecosystems, risk to infrastructure, and loss of life. The Labor Day Fires of 2020 provided an opportunity to compare multiple large and severe wildfires with the objective of determining potential changes to hydrologic processes in Oregon Cascades watersheds. Geographic information systems (GIS) were implemented to determine the total percentage burned and percentage of high burn severity class of six watersheds on the west-slope of the Oregon Cascade Range. In addition, two control watersheds were included to contrast the influence of climatic effects. Spatial arrangement of …


Limited Rigor In Studies Of Raptor Mortality And Mitigation At Wind Power Facilities, Tara J. Conkling, Christopher J.W. Mcclure, Sandra Cuadros, Scott R. Loss, Todd E. Katzner Aug 2022

Limited Rigor In Studies Of Raptor Mortality And Mitigation At Wind Power Facilities, Tara J. Conkling, Christopher J.W. Mcclure, Sandra Cuadros, Scott R. Loss, Todd E. Katzner

United States Geological Survey: Staff Publications

Wind power is an expanding source of renewable energy. However, there are ecological challenges related to wind energy generation, including collisions of wildlife with turbines. Lack of rigor, and variation in study design, together limit efforts to understand the broad-scale effects of wind power infrastructure on wildlife populations. It is not clear, however, whether these types of limitations apply to groups of birds such as raptors that are particularly vulnerable to negative effects of wind energy. We reviewed 672 peer-reviewed publications, unpublished reports, and citations from 321 wind facilities in 12 countries to evaluate methods used to monitor and mitigate …


Assessment Of Water Quality, Fish Diversity, And Lead (Pb) In The Agriculturally Dominated Upper Cache River Watershed, Arkansas, Amelia K. Atwell Aug 2022

Assessment Of Water Quality, Fish Diversity, And Lead (Pb) In The Agriculturally Dominated Upper Cache River Watershed, Arkansas, Amelia K. Atwell

Student Theses and Dissertations

Freshwater is an important, finite, commodity necessary for nearly all facets of human life. Due to its vast usage, a large portion of freshwater has become impaired, impacting water quality. Worldwide, pollution from rivers and streams are causing eutrophication in marine environments into which they flow, negatively affecting aquatic life. The hypoxic zone in the Gulf of Mexico has reached record size in the last decade with agricultural activity within the Mississippi River Basin, including the Cache River Watershed of northeast Arkansas, contributing to the cause. Over 70% of the Cache River Watershed is used for agriculture and the upper …