نتایج جستجو برای: mining coal mining
تعداد نتایج: 114364 فیلتر نتایج به سال:
Labor productivity in U.S. coal mining increased at an average annual rate of slightly over four percent during the past 45 years. This report examines key factors contributing to that record particularly, technological innovation in both surface and underground mining and concurrent geographic shifts in U.S. coal production. Health, safety, and environmental regulations introduced in the sixti...
Studies conducted on surface coal mining equipment have identified whole-body vibration as a significant hazard. Operators of underground mobile equipment, particularly shuttle cars and transport vehicles, are likely to be exposed to significant levels of whole-body vibration. To date, measuring whole-body vibration from underground mining mobile equipment has been difficult due to the strict g...
Lithological characteristics, mineral composition, physical properties of water and physical and mechanical properties, weathering zone distribution and other factors of bedrock weathering zone in coal-seam roof determine the strength of its watertight performance, while its performance has a direct impact on impermeable overlying loose surface water aquifers as well as the possible collapse in...
Mountaintop mining is the dominant form of coal mining and the largest driver of land cover change in the central Appalachians. The waste rock from these surface mines is disposed of in the adjacent river valleys, leading to a burial of headwater streams and dramatic increases in salinity and trace metal concentrations immediately downstream. In this synoptic study we document the cumulative im...
There are many coal seams in high-gas mining area of China. The permeability is low. The gas extraction from the original coal seam is difficult and the commercial value is little. The conception of the safe high-efficient exploitation of coal and gas is put forward in this article. It changes the conventional exploitation sequence that is from the upper to below. When we exploit coal seams, th...
The Appalachian region of USA hosts diverse forests and abundant high-quality coal reserves. Surface mining methods are often used for coal extraction. Because common reclamation methods in past years have not restored forest vegetation, surface mining has created a diverse land base. Although some mined lands have been placed into managed uses, most have not. Little is known about the extent a...
Cancer incidence and mortality rates are high in West Virginia compared to the rest of the United States of America. Previous research has suggested that exposure to activities of the coal mining industry may contribute to elevated cancer mortality, although exposure measures have been limited. This study tests alternative specifications of exposure to mining activity to determine whether a mea...
The problem of abandoned land from mining activities is aggravated since the coal boom. Activities of excavating coal exscind natural vegetation and deposit stone on the natural land that modified the natural land contribute to waste farmlands. This paper presents the comparableness of SVMs method to artificial neural networks in the outlier detection problem of high dimensions. Experiments per...
This paper constructs a forecasting model for coal mining water inrush from the floor through the analysis and careful study of the mechanism of water inrush in coal mining and the Self-Adaptive Evolutionary Extreme Learning Machine (SaE-ELM) which obtains self-learning, generalization performance and speediness is used. In SaE-ELM, the network hidden node parameters are optimized by the self-a...
The most important determinant of whether there is a radon problem is the presence of uranium and radium in the bedrock and overburden. As the permeability of the ground controls the ease with which radon can be transported, any cavity that exists underground has the potential to accumulate elevated levels of radon. Buildings built upon the ground surface have the potential to draw in ground ga...
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