The electromotive force generated in a circuit containing two dissimilar
metals when one junction is at a different temperature from the other.
ASM, 1
The thermal emissivity, or heat transfer coefficient, of a rock surface is
the rate at which heat will flow from rock to air, per unit area for 1
degree temperature difference. This varies with color and other surface
characteristics. Measured in W/m2 .K. Roberts, 1
The increase in linear dimensions and volume that occurs when materials
are heated and that is counterbalanced by a contraction of equal amount
when the materials are cooled. Harbison-Walker
In the Earth, the rate at which temperature increases with depth below the
surface. In a mine, this is usually estimated at 5.3 degrees F/1,000 ft (1
degrees C/100 m) of shaft depth. Some variability with time of day is
typically observed. SME, 1
A type of metamorphism resulting in chemical reconstitution controlled by
a temperature increase, and influenced to a lesser extent by confining
pressure; there is no requirement of simultaneous deformation.
See also:pyrometamorphism
load metamorphism; static metamorphism. Syn:thermometamorphism
AGI
An instrument for obtaining information regarding the number of particles
present in unit volume of a dust cloud, together with their size
distribution. This is probably the most efficient instrument used for dust
counts since its efficiency is practically 100% for all particles from 0.2
to 10 mu m in diameter. See also:Hexhlet sampler; dust sampling.
A device used for measuring the heat flow out of ocean bottom sediment.
Hunt
A system of geophysical prospecting based on measuring underground
temperatures or temperature gradients and relating their irregularities to
geological deformation. AGI
A nuclear reactor in which the fission chain reaction is sustained
primarily by thermal neutrons. Most reactors are thermal reactors.
Lyman
A device that brings water sprays into action when heating occurs on
roadway belt conveyors. The local heat fuses an element holding taut
wires. On release by fusion, the wires allow spray valves to open and the
water cools the affected area. Nelson
See:resistance
See:resistivity
The separation of minerals and metals by heat. The method is used, e.g.,
to remove impurities from rock salt. The crude salt is first exposed to
radiant heat. The impurities absorb the heat and become warm, while the
rock salt transmits the radiant heat and remains cool. The warm, impure
particles adhere slightly to a belt covered with heat-sensitive resin,
while the salt remains free. Separation takes place at the end of the
belt. The cool salt is thrown into one container, while the adhering
impurities drop directly into another. Nelson
Failure of a material, esp. a brittle material, due to the thermal stress
of rapidly rising or falling temperature. AGI
The ability to withstand sudden heating, cooling, or both without cracking
or spalling.
The chipping or spalling of ceramic ware by repeated heating and cooling.
A spring whose water temperature is appreciably higher than the local mean
annual atmospheric temperature. AGI
thermal value (volatile matter)
The calorific value of volatile matter in therms per ton of dry coke, of
the gas given off when dry coke, ground to pass a 36-mesh B.S. test sieve,
is heated under standard conditions. BS, 1
Water, generally of a spring or geyser, whose temperature is appreciably
above the local mean annual air temperature. AGI
a. A method of boring holes in concrete under the high temperature
generated by a burning steel tube, known as a lance. This is packed with
steel wool, through which a jet of suitable gas flows to ignite the end of
the lance and keep it burning. Hammond
b. See:jet piercing
See:jet piercing