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Results 631 - 640 of 646
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7/1/1982 - Conference papersA new phone system was developed that provides eight full duplex communications channels over a single twisted shielded phone line, with no central switching station or line amplifiers. This system greatly simplifies installation and maintenance over th...
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7/1/1982 - Conference papersA medium-frequency (MF) communication system has been built and has been tested in underground mines. It provides radio coverage to vehicles and personnel anywhere in the mine via parasitic coupling into existing mine conductors.
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7/1/1980 - Conference papersA summary is presented of existing leaky feeder communications systems currently in operation in North America. Background information pertaining to previous use of leaky feeder technology is discussed along with the survey methodology.
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7/1/1980 - Conference papersField studies have been conducted in a large number of coal mines throughout the U.S. to determine the effectiveness of electromagnetic techniques in locating men trapped underground following a mine disaster.
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10/1/1978 - Conference papersAn analysis is made of the trolley line as a communications line, and methods of improving its characteristics are discussed.
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10/1/1978 - Conference papersElectric shocks are a serious problem in the mining environment. Electrical accidents, resulting in personal injury, due to improper or complete lack of grounding of electrically operated mining machines, form a significant percentage of the overall ele...
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10/1/1978 - Conference papersThe analysis of a machine-luminaire configuration is well suited to computer analysis; the incident light levels can be calculated at the required set of points. This paper presents a description of the techniques involved in this simulation.
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10/1/1978 - Conference papersThe current state of the art of fire and smoke detection technology is reviewed from the standpoint of suitability for use in underground metal and nonmetal mines. Detection modes, fire signatures, and environmental considerations are included. Prelimin...
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10/1/1978 - Conference papersVarious silicone materials have been proposed for use in mining environments. The catalytic methane sensors now employed are poisoned by silicone vapors. Activated charcoal and carbon cloth adsorbents will increase the sensor lifetimes in an environment...
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8/1/1978 - Conference papersMedium-frequency (MF) waves can propagate in a coal seam, bounded above and below by conducting rock, in an approximate transverse electro-magnetic (TEM) transmission-line mode with the electric field vertical and the magnetic field horizontal. The theo...
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Content source: National Institute for Occupational Safety and Health, Mining Program