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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Development and Demonstration of a Standard Methodology for Respirable Coal Mine Dust Characterization Using SEM-EDX

Sellaro, Rachel Mary 09 July 2014 (has links)
The purpose of this thesis is to examine the potential for a more comprehensive method of analysis of coal mine dust. Respirable dust is specifically of interest due to its ability to cause occupational lung disease when miners are overexposed to airborne concentrations. A detailed standard methodology to characterize respirable mine dust is carefully investigated with the use of scanning electron microscopy with energy dispersive x-ray (SEM-EDX). In addition to a thorough description of the developed particle level characterization approach, the method is demonstrated with underground respirable dust samples collected from an underground coal mine in Central Appalachia. Results of this thesis indicate that a comprehensive dust characterization method is possible and can be efficient and effective, when standardized. This analytical approach uses measured compositions, dimensions, and shapes to produce an abundance of data in even a single sample of dust. Verification results show the method is suitable for analysis of respirable particles of common coal mine mineralogy and analysis of many samples in a timely manner. The results obtained from the underground samples in Central Appalachia reveal the quantity of information which can be generated using the developed method. The amount of data which is acquired using the more comprehensive dust characterization method may aid in understanding the health effects of various dust characteristics. / Master of Science
112

Optimizing secondary tailgate support selection

Harwood, Cary P. 18 September 2008 (has links)
A model was developed to facilitate secondary tailgate support selection based on analysis of a data base of over 100 case studies compiled from two different surveys of operating longwall coal mines in the United States. The ALPS (Analysis of Long wall Pillar Stability) program was used to determine adequacy of pillar design for the successful longwall case histories. A relationship was developed between the secondary support density necessary to maintain a stable tailgate entry during mining and the CMRR (Coal Mine Roof Rating). This relationship defines the lower bound of secondary support density currently used in longwall mines. The model used only successful tailgate case history data with adequate ALPS SF according to the CMRR for each case. This model facilitates mine design by predicting secondary support density required for a tailgate entry depending on the ALPS SF and CMRR, which can result in significant economic benefits. / Master of Science
113

The Effects of Microhabitat and Land Use on Stream Salamander Occupancy and Abundance in the Southwest Virginia Coalfields

Sweeten, Sara 09 April 2015 (has links)
Large-scale land uses such as residential wastewater discharge and coal mining practices, particularly surface coal extraction and associated valley fills, are of particular ecological concern in central Appalachia. Identification and quantification of both large-scale land use and microhabitat alterations to ecosystems are a necessary first-step aid in mitigation of negative consequences to biota. In central Appalachian headwater streams absent of fish, salamanders are the dominant, most abundant vertebrate predator providing a significant intermediate trophic role. Stream salamander species are considered to be sensitive to aquatic stressors and environmental alterations with past research having shown linkages among microhabitat parameters, and large-scale land use such as urbanization and logging to salamander abundances. However, there is little information examining these linkages in the coalfields of central Appalachia. In the summer of 2013, I visited 70 sites (sampled three times each) in the southwest Virginia coalfields to collect salamanders and quantify stream and riparian microhabitat parameters. In an information-theoretic framework I compared the effects of microhabitat and large-scale land use on salamander occupancy and abundances. My findings indicate that dusky salamander (Desmognathus spp.) occupancy and abundances are more correlated to microhabitat parameters such as canopy cover than to subwatershed land uses. Brook salamander (Eurycea spp.) occupancy show negative associations to large-scale land uses such as percent recent mining and percent forested. Whereas Eurycea spp. abundances are negatively influenced by suspended sediments, stream bank erosion and stream substrate embeddedness. Management implications of these findings include erosion prevention and control as well as protection and management of riparian habitats. However, quantifying physical environmental quality such as stream and riparian habitat often can be quite difficult, particularly when there are time or fiscal limitations. In order to accurately assess stream and riparian habitat in a time- and cost- effective manner, the U.S. Army Corps of Engineers (USACE) developed a functional condition index (FCI) assessment for streams that measures 11 stream and riparian parameters along with watershed land use to calculate three different scores: a hydrology score, biogeochemical score, and habitat score (Noble et al 2010). Using the salamander data from 2013, I then analyzed the FCI scores using collected occupancy and abundance analyses. Both analyses supported the Habitat FCI score as it had strong correlations with both occupancy and abundance of three Desmognathus spp., and support the use of the USACE protocol for stream and riparian habitat assessment. / Ph. D.
114

Temporal Dynamics of Benthic Macroinvertebrate Communities and Their Response to Elevated Specific Conductance in Headwater Streams of the Appalachian Coalfields

Boehme, Elizabeth A. 27 August 2013 (has links)
Prior studies have demonstrated Appalachian coal mining often causes elevated specific conductance (SC) in streams, and others have examined SC effects on benthic macroinvertebrate communities using point-in-time SC measurements. However, both SC and benthic macroinvertebrate communities exhibit temporal variation. Twelve Appalachian headwater streams with minimally impacted physical habitat and reference-quality physicochemical conditions (except elevated SC) were sampled ten to fourteen times each for benthic macroinvertebrates between June 2011 and November 2012. In situ loggers recorded SC at 15-minute intervals. Streams were classified by mean SC Level (Reference 17-142 S/cm, Medium 262-648 S/cm, and High 756-1,535 S/cm). Benthic macroinvertebrate community structure was quantified by the Virginia Stream Condition Index and other metrics. Structural metric differences among SC Levels and month of sampling were explored. Reference-SC streams exhibited significantly higher scores on most metrics, supporting previous findings that SC may act as a biotic stressor, even in streams lacking limitations from degradation of physical habitat or other physicochemical conditions. Temporal variation was greatest in Medium-SC streams, which had the most metrics exhibiting significant differences among months and the greatest range of monthly means for six metrics. Metrics involving % Plecoptera and/or % Trichoptera were not sensitive to elevated SC, as Leuctridae and Hydropsychidae exhibited increased abundance in streams with elevated SC. Best scores for benthic macroinvertebrate community metrics differed based on selected metric, SC Level, and month. Consequently, timing of sampling is important, particularly in streams with elevated SC because community metric scores may be impacted by dominant taxa life history patterns. / Master of Science
115

Improvement of Ground-Fault Relaying Selectivity through the Application of Directional Relays to High-Voltage Longwall Mining Systems

Basar, Joseph James 05 May 2004 (has links)
The continuing trend toward larger longwall mining systems has resulted in the utilization of higher system voltages. The increase in system voltage levels has caused the industry to face complexities not experienced with the lower-voltage systems. One such complexity arises from the larger system capacitance that results from the outby configuration commonly used on 4,160-V longwall power systems. Simulations show that during a line-to-ground fault, the larger system capacitance can cause a situation where the ground current sensed by the ground-fault relays in unfaulted circuits is greater than the mandated ground-fault relay pick-up setting. Simulations show that ground-fault relaying selectivity is potentially lost as a result of this situation. Two alternatives were identified which could improve ground-fault relaying selectivity. They are: the application of a directional relaying scheme and increasing the ground-fault relay pick-up setting. It was determined that directional relays have an application to high-voltage longwall power systems as the ground current sensed by the relay in the unfaulted circuits is out of phase with the ground-fault current sensed by the relay in the faulted circuit. Furthermore, it was determined that raising the ground-fault relay pick-up setting by a factor of eight would also improve ground-fault relaying selectivity. A safety analysis considering the potential for electrocution and the power dissipated by the maximum fault resistance showed that increasing the pick-up setting by a factor of eight would have no detriment to safety. Therefore, either method would improve ground-fault relaying selectivity on high-voltage longwall mining systems, yet because of the escalating size of longwall systems, a directional relaying scheme is a longer term solution. / Master of Science
116

Searching West Virginia for a Democratic Response to Mountaintop Removal

Darrow, Robert 01 June 2010 (has links)
Mountaintop removal is an aggressive form of strip mining practiced almost exclusively in Central Appalachia, and since 1977 has been regulated by state and federal laws. Beginning in the late 1990s, considerable controversy erupted in coal mining states like West Virginia, Kentucky and Tennessee over the adverse social and environmental impacts of the practice. The analysis of mountaintop removal presented here is restricted to its effects in West Virginia during roughly the last decade. Relying on theories of democratic practice developed by pragmatic philosophers like John Dewey and G.H. Mead, this work studies the standard practices of state and federal regulatory agencies and elected officials in an effort to determine what, if any, social goods they work to defend. Pragmatic theories of democracy suggest that a government can be considered representative only when it acts on behalf of the public good. Chapter 1 of this thesis introduces the reader to the practice of mountaintop removal mining in West Virginia. Chapter 2 lays the theoretical groundwork for determining an individual's or institution's values through an analysis of its habitual actions. In chapter 3, I examine the consequences of mountaintop removal for the state of West Virginia, its citizens, and the coal interests that operate within its borders. Chapter 4 is dedicated to an analysis of regulatory responses to the conflicting interests of the various groups affected by the practice. Finally, in Chapter 5, some conclusions are drawn about the extent to which the regulation of mountaintop removal in West Virginia can be considered democratic. / Master of Arts
117

Stream functional response to mountaintop removal and valley fill coal mining

Maxwell, Corrie 10 June 2009 (has links)
Mountaintop removal and valley fill (MTRVF) mining has become a widespread means of coal extraction in the central Appalachians. During MTRVF several hundred meters of overburden are removed to access coal seams, and excess rubble is dumped into adjoining valleys and streams. Filling valleys eliminates stream headwaters and may result in loss of stream ecosystem functions, which are dependent on temporal and lateral connectivity in river networks. To determine the affect of MTRVF on stream ecosystem function, leaf breakdown, which is an ecosystem level attribute of forested streams, was measured in five streams draining MTRVF sites and five reference streams in central West Virginia. Leaf packs of white oak and red maple were installed in these streams in December 2007, leaves were collected in January, February, March, April, and June of 2008, and leaves were washed and processed in the lab. Leaf breakdown rates were significantly slower in filled streams. MTRVF streams were marked by high sediment levels, elevated base flow, elevated conductivity and pH, and a lower density and richness of shredding macroinvertebrates than reference sites, suggesting that slower leaf decay was the result of the combined set of altered conditions in MTRVF streams. Additionally, MTRVF streams showed no species-level difference between red maple and white oak breakdown rates, indicating that MTRVF inhibits control of ecosystem function exerted by leaf species characteristics. / Master of Science
118

Macroinvertebrate Community Response to Spatial Patterns of Water Quality and Habitat within Mining-influenced Headwater Streams of Appalachia

McMillan, Melanie 07 June 2023 (has links)
Benthic macroinvertebrates are heavily relied on to indicate stream condition because of their ease of sampling, broad span of sensitivities to pollution among taxa, and diverse life histories that utilize various habitats and environmental conditions. Surface-coal mining in central Appalachia often results in salinization of headwater streams, with documented responses in macroinvertebrate communities across streams that vary in specific conductance (SC), an index of degree of salinization. Mining-influenced headwater streams can also exhibit within-stream spatial variation in SC, frequently via dilution with downstream distance from mining. However, the extent to which coal-mining alters downstream patterns in water chemistry and macroinvertebrate communities is largely unknown. This study aimed to determine macroinvertebrate community responses to physical and chemical gradients within six Appalachian headwater streams (four mining-impacted, two reference). Streams were sampled for benthic macroinvertebrates, habitat characteristics, and water chemistry in fall 2021 and spring 2022 at six-to-nine locations per stream over a range of 1.5 – 3 km. Mining-impacted streams exhibited greater spatial variation in macroinvertebrate community composition compared to reference streams, particularly in spring. Bray-Curtis Community similarity determined highly-impacted streams experienced the greatest within-stream shifts in community similarity. Metrics of macroinvertebrate communities and community similarity showed some correlation with SC at within-stream scales, particularly in highly impacted streams in spring; however, such trends were much fewer and weaker compared to relationships among streams when collectively examining communities. Redundancy Analysis (RDA) and Variation Partitioning (VP) indicated water quality, habitat, and location do overlap in explanation of community variation although they often additionally explain variance in unique ways. Significant variables identified by RDA within at least two of the six streams include channel slope, streamwater nutrients and hardness, stream channel embeddedness, and percent fines comprising the streambed. Redundancy Analysis also indicated 18 key macroinvertebrate taxa in study streams responding to location within stream, habitat, and water quality. Of those 18 taxa shredders, collectors, and clingers were most frequently impacted. Improved understanding of the spatial scale of coal-mining influences on headwater stream characteristics will help inform bioassessment protocols to most accurately assess stream condition, and inform remediation efforts within the central Appalachian region and in other salinized stream systems. / Master of Science / Small streams (or headwater streams) originating in the central Appalachian Mountains harbor a variety of unique organisms and are essential to the quantity and quality of downstream freshwater for fishing, recreation, and other uses. Coal mining processes, including disturbance of coal-bearing bedrock, often increases the streams salinity by adding pollutants that elevate dissolved minerals, or salts. Salinization of streams can come from a variety of sources in addition to coal mining such as de-icing road salts and crop irrigation and is of growing concern regarding its impacts to the quality of freshwater available for wildlife and human use. A common way to determine stream health is by identifying which aquatic insects (or macroinvertebrates) are present in a stream, because different groups are present based on the type and intensity of a variety of pollutants. Previous studies determined stream health by identifying insects from one location in a stream and comparing it to others. Stream's habitat and water quality naturally change as they join with larger rivers and flow to lower elevations causing different macroinvertebrates to be present at locations within streams. This study aimed to determine how changes along stream distances may be different in streams salinized from coal mining. The objectives of this study were to determine if one sample is adequate to represent the entire condition of a headwater stream. Six streams were sampled for macroinvertebrate, water quality, and habitat at six-to-nine locations within each stream over distances of ca. 2,000 m. Four streams were impacted by mining, of which two were highly impacted and two were impacted to a low-level; the last two streams were unimpacted to represent reference condition. The study found the type and number of macroinvertebrates within streams were changing least within reference streams and most in highly impacted streams. Macroinvertebrate communities in highly-impacted streams changed more within streams because they had high concentrations of dissolved salts upstream near the source of coal-mining pollution and these salts diluted with distance downstream, most likely due to fresh spring water contributions with minimal dissolved salts. Therefore, highly-impacted headwater streams experience greater environmental and macroinvertebrate variability indicating more than one sample location may be helpful in accurately assessing what macroinvertebrates inhabit the stream length of interest. Ensuring accurate sampling technique to determine stream condition is essential to our understanding of stream health and how to remediate and monitor impacts of salinization on our freshwater resources.
119

The arbitration review board: an analysis of its development and impact on the arbitration process in the coal industry

Bourne, Glen Steve January 1987 (has links)
The Arbitration Review Board existed in the bituminous coal industry from 1974 to 1981. Established during the 1974 contract negotiations between the Bituminous Coal Operators Association and the United Mine Workers of America, the ARB represented an effort to obtain consistency in arbitration decisions. The ARB operated as an industry appellate board designed to hear appeals of arbitration awards, and the decisions of the ARB were contractually mandated as industry precedents requiring arbitrator compliance. Although the parties terminated the ARB in 1981, they have continued to incorporate the precedent decisions in subsequent contracts. This study utilizes both a qualitative assessment and an empirical analysis of arbitration decisions to determine the impact of the ARB on the arbitration process in the coal industry. Structured interviews were conducted with former ARB members, arbitrators, management representatives, and union representatives to gather information with which to construct a complete historical perspective of the ARB's inception, operation, and termination. A total of 44 individuals were interviewed. The empirical assessment involved a content analysis of 300 arbitration decisions to determine the extent to which arbitrators have adhered to the ARB precedents. Conclusions of the research suggest that the ARB has had a profound impact on coal industry arbitration. Arbitrators increasingly adhered to ARB decisions during its existence, and have continued to exhibit a high degree of adherence following the ARB's termination. The difficulties encountered in implementing the ARB and the factors contributing to its termination are discussed. / Ph. D.
120

A mixed integer model for optimizing equipment scheduling and overburden transport in a surface coal mining operation

Goodman, Gerrit V. R. January 1987 (has links)
Recently, competition has increased in the surface coal mining industry, which has necessitated the development of more efficient methods for coal removal. Despite this trend, very little emphasis has been placed on the development of optimization techniques applicable to the surface coal industry. The available methods are inadequate in that they recognize neither the complex equipment interactions present in a surface mining operation nor the interdependence of overburden removal and spoil placement. The lack of available techniques prompted the development of a mixed integer model to optimize the scheduling of equipment and the distribution of overburden in a typical mountaintop removal operation. Using this format, a (0-1) integer model and transportation model were constructed to determine the optimal equipment schedule and optimal overburden distribution, respectively. To solve this mixed integer program, the model was partitioned into its binary and real-valued components. Each problem was successively solved and their values added to form estimates of the value of the mixed integer program. Optimal convergence was indicated when the difference between two successive estimates satisfied some pre-specified accuracy value. The performance of the mixed integer model was tested against actual field data to determine its practical applications. To provide the necessary input information, production data was obtained from a single seam, mountaintop removal operation located in the Appalachian coalfield. As a means of analyzing the resultant equipment schedule, the total idle time was calculated for each machine type and each lift location. Also, the final overburden assignments were analyzed by determining the distribution of spoil material for various overburden removal productivities. Subsequent validation of the mixed integer model was conducted in two distinct areas. The first dealt with changes in algorithmic data and their effects on the optimality of the model. The second area concerned variations in problem structure, specifically those dealing with changes in problem size and other user-inputted values, such as equipment productivities or required reclamation. For each of these optimal schedules and assignments obtained from the model, analyses were conducted in manner similar to that discussed above. / Ph. D.

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