Metamorphism accomplished under conditions of high temperature and
pressure. See also:metamorphic grade
high-ratio resistance controller
This controller gives a high ratio of maximum to minimum resistance,
6,000:1. A high resistance is thus available for reverse-current braking,
but the design ensures that there is an ample volume of electrolyte
between the electrodes when starting at twice full-load torque. It is
similar to the swinging-electrode controller. Sinclair, 5
The bedrock or reef rising from the lowest and richest part of an alluvial
placer and forming the slopes of the ancient valley.
Deposits of wash dirt upon the high reef.
high-resolution seismic technique
A seismic prospecting technique in which a special recording system yields
readable reflections from layers less than 10 ft (3 m) thick at depths as
little as 100 ft (30 m). Dobrin
The entire world's oceans except for the portion lying shoreward of the
outer limit of the territorial seas. United Nations
A deep coal-mine car, i.e., one with high sides. CF:gondola
Fay
See:natural ore
Synonymous with advanced sintering at high temperatures, usually the final
sintering close to the melting point of the material. Osborne
high-temperature bonding mortar
A mixture of refractory materials, either raw or calcined, to which other
materials not classified as refractory materials have been added for the
purpose of increasing the plasticity, giving air-setting properties, and
lowering the temperature at which the bond develops. Henderson
A type of structural steel having a maximum yield point of 23 st/in (super
2) as compared with 15.25 st/in2 for mild steel.
See also:yield stress
A high-voltage transmission line.
In mineral processing, the use of high-voltage direct current at between
18,000 V and 80,000 V to charge small particles of dry material as they
fall through its field (emanating as a spray or a point discharge). These
are then sorted into relatively charge-retaining and charge-losing
minerals in accordance with their conducting power. Also called
electrostatic separation. Pryor, 3
See:velocity
high volatile A bituminous coal
The rank of coal, within the bituminous class of the Classification D 388,
such that on the dry and mineral-matter-free basis, the volatile matter
content of the coal is greater than 31% (or the fixed carbon content is
less than 69%), and its gross calorific value is equal to or greater than
14,000 Btu/lb (32.54 MJ/kg) of coal on the moist, mineral-matter-free
basis, and the coal is commonly agglomerating. ASTM
high volatile B bituminous coal
The rank of coal, within the bituminous class of Classification D 388,
such that, on the moist mineral-matter-free basis, the gross calorific
value of the coal in British thermal units per pound is equal to greater
than 13,000 (30.24 MJ/kg) but less than 14,000 (32.54 MJ/kg) and the coal
commonly agglomerates. ASTM
high volatile C bituminous coal
The rank of coal, within the bituminous class of Classification D 388,
such that, on the moist, mineral-matter-free basis, the gross calorific
value of the coal in British thermal units per pound is equal to or
greater than 11,500 (26.75 MJ/kg) but less than 13,000 (30.24 MJ/kg) and
the coal commonly agglomerates, or equal to or greater than 10,500 (24.42
MJ/kg) but less than 11,500 (26.75 MJ/kg) and the coal agglomerates.
ASTM
Coals containing over 32% volatile matter with a coal rank code No. 400 to
900. See also:coal classification
a. A high electrical pressure or electromotive force.
b. In coal mining, voltages above 1,000 V. CF:low voltage;
medium voltage. Federal Mine Safety
The unexcavated face of exposed overburden and coal or ore in an opencast
mine, or the face or bank on the uphill side of a contour strip mine
excavation.
The plane of high water. Schieferdecker