- 行业: Mining
- Number of terms: 33118
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- Company Profile:
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 ...
This instrument applies the veiling brightness method of producing threshold conditions. When in use the sighting telescope is directed toward some critical detail of the visual task and the veiling brightness is adjusted until it matches the background. The gradient filter is then turned until the target detail is at threshold visibility.
Industry:Mining
This instrument consists essentially of a damped, pivoted vane that is deflected when placed in an airstream. As the weight of the vane is constant, the angle of inclination will be dependent upon the rate of change of momentum of the impinging airstream. The instrument gives a direct reading and can be calibrated for use over a wide range of velocities, from 20 to 2,000 ft/min (6.1 to 609.6 m/min). In underground airways, it can be used without attachments. Its main use is the measurement of air velocity in ducts and the rate of air discharge from ventilating grills.
Industry:Mining
This instrument has been used over a wide range of lighting applications. It consists of a pair of similar photographic gradient filters, which increase in density as they are rotated together before the eyes. The filters therefore reduce the apparent brightness of the observed field and at the same time lower the contrast between the object of view and its background.
Industry:Mining
This instrument is used for studying the temperature structure in the upper 10 m of water. The instrument is in two sections; a float, which contains a spooling winch from which the sensing unit is lowered, and an indicator case, which contains the remote indicating equipment and remote control system. The two sections are connected by an electric cable and flexible shaft, supported by net floats. The indicator case is clear lucite. It contains the indicating meter and electric circuitry for temperature determination. It also contains a Veeder-Root counter, which indicates directly in centimeters the depth at which the sensing unit is located. This instrument makes it possible to read temperature to within 0.1 degrees C and to know the depth of the sensing unit to within + or -0.5 cm. It is intended to be used at sea from a skiff or tender rather than from the research vessel itself.
Industry:Mining
This instrument measures barometric pressure and is quite accurate for a portable instrument. It can be used for finding the difference in pressure between points at various elevations without checking the setting of the pointer, or it can be checked against a mercury barometer and then used as a portable barometer. It is useful in making a survey of the drop in ventilation pressure throughout a mine.
Industry:Mining
This instrument measures temperature, pressure, and sound velocity to depths up to 7 miles (11.2 km). The device is completely transistorized and uses frequency modulation for telemetering.
Industry:Mining
This involves the placing of fairing around or over obstructions to airflow, in such a way as to change that flow from turbulent to laminar.
Industry:Mining
This is a cut with a single V where all the holes on one side are parallel and meet the holes from the other side at an angle that may be as low as 30 degrees .
Industry:Mining
This is a general term applied to switching, interrupting, controlling, metering, protective, and regulating devices, as well as assemblies of these devices with associated interconnections, accessories, and supporting structures. The term is used primarily in connection with generation, transmission, distribution, and conversion of electric power.
Industry:Mining
This is a measure of the energy available per weight of explosive as compared to an equal weight of ANFO. It is calculated by dividing the absolute weight strength (AWS) of the explosive by the AWS of ANFO and multiplying by 100.
Industry:Mining
