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Results 61 - 70 of 74
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9/1/1974 - Contract reportsTwo different techniques were used to make measurements of the absolute value of electromagnetic noise in and above an operating coal mine, McElroy Mine, located near Moundsville, West Virginia. The electromagnetic environment created by 300-volt dc and...
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9/1/1974 - Contract reportsTwo different techniques were used to make measurements of the absolute value of electromagnetic noise in an operating hardrock mine, Grace Mine, located near Morgantown, Pennsylvania.
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9/1/1974 - Contract reportsMeasurements of surface magnetic field noise were made at various locations over the Geneva Coal Mine near Price, Utah, on June 12, 1973. Results of measurements of distant sferics indicate rather sharp cutoff frequencies below which broadband, impulsiv...
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9/1/1974 - Contract reportsVolume I of this report deals with theoretical, experimental, and practical implementation aspects of the federal Bureau of Mines programs related to present and planned, emergency and operational, mine communications and miner location systems for unde...
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9/1/1974 - Contract reportsTwo different techniques were used to make measurements of the absolute value of electromagnetic noise in an operating coal mine, Robena No. 4, located near Waynesburg, Pennsylvania. One technique measures noise over the entire electromagnetic spectrum ...
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7/14/1974 - Contract reportsThis report describes a circuit for driving a low-frequency loop antenna from a miners cap lamp battery. The circuit is a miniature waveform generator and is part of the electromagnetic (em) trapped miner location system. Two engineering models were des...
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7/1/1974 - Contract reportsVolume II of this report (Contract No. H0122026) presents the findings of a short intensive assessment performed during the fall of 1972. This assessment provided the federal Bureau of Mines with independent technical judgments regarding the potentials ...
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1/10/1974 - Contract reportsField studies of ambient electromagnetic noise and electrical transmission properties of coal mine overburdens in Colorado, Illinois, Pennsylvania, and West Virginia were conducted. Field tests of the transmission of low-frequency (20 hz to 20,000 hz) s...
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12/1/1973 - Conference proceedings, Contract reportsA need arose to assemble individuals who have been active in current research on the topic of electromagnetic communications systems so that the problem of how information may be conveyed by electromagnetic waves propagating through rock media without t...
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9/1/1973 - Contract reportsSix different types of blasting caps, mainly of the type used in coal mines, were evaluated to determine both their radio frequency and direct current characteristics.
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Content source: National Institute for Occupational Safety and Health, Mining Program