Abstract: Apparatus for monitoring the position of a mining machine cutting a new entry in a coal seam relative to an adjacent, previously cut entry to determine the distance between a near face of the adjacent previously cut entry and a new face adjacent thereto of a new entry being cut by the mining machine which together define the thickness of a coal rib being formed between the new entry and the adjacent previously cut entry during the new entry-cutting operation. The monitoring apparatus; includes a transmit antenna mounted on the mining machine and spaced inwardly from the new face of the coal rib for transmitting radio energy towards the coal rib so that one portion of the radio energy is reflected by the new face which is defined at an air-coal interface between the new entry and the coal rib and another portion of the radio energy is reflected by the near face of the coal rib which is defined at an air-coal interface between the coal rib and the adjacent previously cut entry.

Abstract: A method and apparatus for on-line diagnostics, particularly for use in power circuits of a DC-DC converter is described. Signals are sensed at selected strategic test points in a circuit and compared with stored expected signals for those points under normal operating conditions. Whenever the signals sensed at the selected test points do not correlate with the corresponding expected signals, the sensed signal is compared with abnormal signals stored in the memory associated with known failure conditions for that test point. Whenever the sensed signal matches closely with a signal for a known failure condition, an indication of the particular failure is logged into memory. If the sensed signal does not match a known failure condition, an indication of an unknown failure condition is logged into memory. Failure information can later be retrieved by maintenance personnel at a convenient time or can be displayed on an operator's display during operation.