Results 631 - 640 of 646

• Medium Frequency Vehicular Control and Communications Systems for Underground Mines
  1/1/1984 - Conference papers
  Theoretical and experimental research sponsored by the U.S. Bureau of Mines shows that medium frequency (MF) electromagnetic (EM) signals propagate great distances in an underground environment such as a tunnel or mine. This propagation is enhanced by d...
• A Multiplexed Phone System for Small Mines
  7/1/1982 - Conference papers
  A 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...
• A Whole-Mine Medium-Frequency Radio Communication System
  7/1/1982 - Conference papers
  A 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.
• An Assessment of Leaky Feeder Radio Systems in Underground Mines
  7/1/1980 - Conference papers
  A 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.
• Assessment of Present Electromagnetic Techniques for the Location of Trapped Miners
  7/1/1980 - Conference papers
  Field 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.
• Improved Rail Haulage Communications
  10/1/1978 - Conference papers
  An analysis is made of the trolley line as a communications line, and methods of improving its characteristics are discussed.
• Electric Shock Prevention
  10/1/1978 - Conference papers
  Electric 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...
• Evaluation of Mine Illumination Systems Using Numerical Modeling
  10/1/1978 - Conference papers
  The 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.
• In-Mine Evaluation of Underground Fire and Smoke Detectors
  10/1/1978 - Conference papers
  The 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...
• Silicone Vapor Poisoning of Catalytic Methane Sensors
  10/1/1978 - Conference papers
  Various 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...