نتایج جستجو برای: mining coal mining
تعداد نتایج: 114364 فیلتر نتایج به سال:
Birth defects are examined in mountaintop coal mining areas compared to other coal mining areas and non-mining areas of central Appalachia. The study hypothesis is that higher birth-defect rates are present in mountaintop mining areas. National Center for Health Statistics natality files were used to analyze 1996-2003 live births in four Central Appalachian states (N=1,889,071). Poisson regress...
In the early 20 th century Japan, coal mining firms took an intermediary organization of labor, “dormitory system.” Given traditional technology that required high manual skills unknown to managements, firms relied on the intermediary organization both for screening and monitoring workers. This study focuses on referrers of miners, who took an essential role of signaling in the coal mining indu...
Background and objectives Mining results in degradation of rangelands ecosystem structure and function. Coal mining in rangelands produces significant quantities of waste dumps in mining area which are considered as the main environmental pollutants in the site and surrounding ecosystems. Vegetation restoration in mining area could reduce soil pollution and could be of great help in restoring ...
Past efforts to estimate methane emissions from underground mines, surface mines, and other coal mine operations have been hampered, to different degrees, by a lack of direct emissions data. Direct measurements have been completely unavailable for several important coal mining operations. A primary goal of this study was to collect new methane emissions measurements and other data for the most ...
in the present study, 45 rainwater samples were collected from february to december 2012 on event basis in east bokaro coal mining environment. physico-chemical and major ionic compositions of rainwater samples as well as water soluble major ion composition were analyzed to employ principle component analysis for source identification. the average ph value was recorded 6.1 and varied from 5.1 t...
In mining of inclined coal seams in Tangshan coal mine of Kailuan group, gateways on either end of a panel were both typically located along the floor and a gateway pillar between adjoining panels was left unmined between adjacent panels to ensure stability, thus forming a planar mining system. According to the practice, however, it turned out that this conventional mining system has long-stand...
We analyze labor productivity in coal mining in the United States using indices of productivity change associated with the concepts of panel data modeling. This approach is valuable when there is extensive heterogeneity in production units, as with coal mines. We ̄nd substantial returns to scale for coal mining in all geographical regions, and ̄nd that smooth technical progress is exhibited by ...
Coal mining in India has a history of over 225 years. The industry currently occupies a covetable third ranking in the world league table of hard coal production after China and the USA. Mechanization has made possible major breakthroughs in coal mining technology. The record of production and productivity of Indian underground coal mines over the years is dismal, to say the least. At the time ...
Coal mining and related industry can increase heavy metals (HMs) concentrations in soil, atmosphere and wheat, thereby posing metal-associated human health risk via food ingestion. In this study, 58 samples of soil, wheat, and dust were collected from Xuzhou coal mine eastern China, six kinds of HMs Pb, Cd, Cu, Zn, As and Cr were studied for their spatial distribution in wheat, enrichment in d...
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