- 行业: Mining
- Number of terms: 33118
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The U.S. Bureau of Mines (USBM) was the primary United States Government agency conducting scientific research and disseminating information on the extraction, processing, use, and conservation of mineral resources.
Founded on May 16, 1910, through the Organic Act (Public Law 179), USBM's missions ...
One of the various tools or wrench devices that can be made to fit and grasp drill rods, casing, or drivepipe.
Industry:Mining
One of the vertical posts at the side of a tunnel resting on sills and carrying the wallplates; collectively, they support the tunnel roof by means of centering.
Industry:Mining
One of three nitrides that have been reported: NbN, Nb<sub>2</sub>N , and Nb<sub>4</sub>N<sub>3</sub>. During reaction between niobium and N<sub>2</sub>at 800 to 1,500 degrees C the product generally consists of more than one compound. Most of the phases are stable at least to 1,500 degrees C.
Industry:Mining
One of three orthogonal optic directions in biaxial crystals. Light with its electric vector (vibration direction in early terminology) parallel to the x-direction has the lowest refractive index (n<sub>alpha</sub>) for a given crystal and is called the fast ray. In orthorhombic crystals, the x-axis is constrained by symmetry to correspond to one of the crystallographic directions, the correspondence determined empirically. In monoclinic crystals, one optic direction, commonly the y-direction, is constrained by symmetry to correspond to the unique diad. In triclinic crystals, there is no symmetrical constraint relating optic directions to crystallographic axes.
Industry:Mining
One of three orthogonal optic directions in biaxial crystals. Light with its electric vector (vibration direction in early terminology) parallel to the z-direction has the highest refractive index (n<sub>gamma</sub>) for a given crystal and is called the slow ray. In orthorhombic crystals, the z-direction is constrained by symmetry to correspond to one of the crystallographic directions, the correspondence determined empirically. In monoclinic crystals, one optic direction, commonly the y-direction, is constrained by symmetry to correspond to the unique diad. In triclinic crystals, there is no symmetrical constraint relating optic directions to crystallographic axes.
Industry:Mining
One of three recognized methods for determining the average velocity of airflow along a mine roadway by an anemometer. This is the general routine procedure applied when measuring air velocities in mine roadways. While the instrument is running, it is slowly and steadily moved up and down a series of imagined vertical lines, so as to cover equal areas in equal time. The total period is usually 1 min for a medium-sized roadway. The integrated reading is then the mean velocity for that section. Compare: division method; singlespot method.
Industry:Mining
One of three recognized methods for determining the average velocity of airflow in a mine roadway by anemometer. This is the precise method of determining the mean velocity of the air current. Compare: single-spot method; traversing method.
Industry:Mining
One of three recognized methods of determining the average velocity of airflow along a mine roadway by anemometer. A velocity reading is taken at the center of the airway and the result is multiplied by the center constant, whose value ranges between 0.8 and 0.9, to give the average velocity of flow. Alternatively, the reading is taken along a midway line at a position some one-seventh to one-third of the width of the airway, measured from the side. At this position, the mean velocity is obtained, so that no adjustment is required. Compare: division method; traversing method.
Industry:Mining
One of two approaches used in plotting seismic reflection data on time cross sections. Center-trace times are the times picked on the two traces from the respective detector groups nearest the shot and on opposite sides. The average of the two times for each reflection is plotted at the shot-point position. The points thus plotted for adjacent shot points are connected by straight lines. Compare: trace-by-trace plotting
Industry:Mining
