Results 261 - 270 of 282

• Research and Development Contract for Coal Mine Communication System: Volume 1 - Summary and Results of System Study
  11/1/1974 - Contract reports
  Eight coal mines were visited to determine their communications usage and requirements. Volume 1 summarizes the entire report and includes both a dissertation on the strengths and weaknesses of various available communication techniques and a set of re...
• Research and Development Contract for Coal Mine Communication System: Volume 3 - Theoretical Data Base
  11/1/1974 - Contract reports
  Eight coal mines were visited to determine their communications usage and requirements. Available equipment was surveyed and evaluated to determine its applicability to the needs of the mines. Volume 3 contains all information used in predicting the per...
• Research and Development Contract for Coal Mine Communication System: Volume 4 - Environmental Measurements
  11/1/1974 - Contract reports
  Eight coal mines were visited to determine their communications usage and requirements. Volume 4 describes the propagation measurements made in selected mines during the project, along with findings resulting from these measurements.
• Electromagnetic Noise in Itmann Mine
  9/1/1974 - Contract reports
  Two different techniques were used to make measurements of the absolute value of electromagnetic noise in an operating coal mine, Itmann No. 3 Mine, located near Mullens, West Virginia. The electromagnetic environment created by 250-volt dc and 550- and...
• Electromagnetic Noise in McElroy Mine
  9/1/1974 - Contract reports
  Two 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...
• Electromagnetic Noise in Robena No. 4 Coal Mine
  9/1/1974 - Contract reports
  Two 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 ...
• Research on the Transmission of Electromagnetic Signals Between Mine Workings and the Surface
  1/10/1974 - Contract reports
  Field 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...
• Peak Methane Concentrations During Coal Mining: An Analysis
  1/1/1974 - Reports of Investigations
  Methane concentration peaks were measured at coal mine working faces during entry development. The statistical distribution of peaks was found to be normal or log normal depending on how well the methane was being mixed into the ventilation airstream.
• Methane Emission from U.S. Coal Mines in 1973, A Survey: A Supplement to IC 8558
  1/1/1974 - Information Circulars
  This Bureau of Mines survey of methane emissions indicates that total daily emissions have declined from 227 mm ft3 in 1971 to 214.7 mm ft3 in 1973. The highest average daily emissions in million cubic feet per day are detailed by state.
• Mine Communications: Proceedings: Bureau of Mines Technology Transfer Seminar, Bruceton, Pa, March 21-22, 1973
  1/1/1974 - Information Circulars
  The Technology Transfer Seminar on Mine Communications held on March 21-22, 1973, at the Pittsburgh Mining and Safety Research Center, Bruceton, Pennsylvania, presented information about recently developed equipment, instruments, and techniques for use ...