Results 291 - 300 of 334

• Development of a Phase Difference of Arrival Technique for Location of Trapped Miners
  9/1/1983 - Open File Reports
  Current technologies for locating trapped miners from the surface are either simple direction finders or time difference pulse systems that have accuracy limitations. Developing technologies using full-vector field measurements at several receiving poin...
• Evaluation of Safety Assessment Methods for the Mining Industry. Volume II: User's Manual of Safety Assessment Methods for Mine Safety Officials
  5/1/1983 - Contract reports
  This study examines a cross section of formal safety analysis techniques developed for the nuclear and aerospace industries, recommending those methods suitable for application to the mining industry and including those methods in a user's manual.
• Above-the-Earth Field Contours for a Dipole Buried in a Homogeneous Half-Space
  1/1/1983 - Reports of Investigations
  An essential element of the USBM electromagnetic location and communication system for trapped miners is knowledge of the surface and above-surface electromagnetic fields created by an underground transmitter.
• A Medium Frequency Wireless Communication System For Underground Mines
  1/1/1983 - Contract reports
  An underground medium frequency radio communications system has been developed and demonstrated in both coal and metal/non metal mines. The principal advantage of the system are its low cost, ease of installation and the ability to provide radio communi...
• Theoretical Noise and Propagation Models for Through-the-earth Communication
  9/1/1982 - Contract reports
  A survey of the literature on extremely low-frequency and very low- frequency atmospheric noise was made.
• 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...
• Evaluation of the Black River Mine Telecommunication System
  2/1/1982 - Contract reports
  An evaluation was made of one of several improved underground communication systems sponsored by the U.S. Bureau of Mines. The system was installed in a typical metal-nonmetal, room-and-pillar mine and utilized ultrahigh frequency repeaters connected to...
• A Feasibility Study for the Detection of Weak Electromagnetic Signal/ Bursts With Hard-Limited Arrays
  11/1/1981 - Contract reports
  A prototype detector using electromagnetic signals for finding trapped miners has previously been built and tested. The signals are generated from transmitters carried on the miner's belt and powered by his head lamp battery and the receiver is a human ...
• Propagation of EM Signals in Underground Metal/Non-Metal Mines: Magma Copper Company - San Manuel Mine
  4/1/1981 - Contract reports
  This report presents test results, data evaluations, and typical system performance expectations based on wireless electromagnetic propagation measurements performed in the MAGMA Copper Company San Manuel mine near Tucson, Arizona during March 30 throug...
• The Implementation of UHF Radio Communications and CCTV Monitoring Systems in a Room and Pillar Metal/Non-metal Mine
  3/1/1981 - Contract reports
  This report describes the design and implementation of UHF radio and closed-circuit television systems in the Black River room and pillar limestone mine near Butler, Pendleton County, Kentucky.