| 摘要 |
<p>The composition of a sample (52) is determined with reference to a recorded standard using the same heater (56) and sensor (58) as that used to record the standard, by testing the sample only when its temperature has reached an equilibrium, and by compensating for differences in environment and starting temperature; accurate heater control is insured by maintaining a constant voltage across a series circuit consisting of a heater (56) and a resistance load (81) equal to resistance of the heater; the heater is pulsed in an initial test sequence to heat the system to above ambient so that heat losses to the environment are substantially the same from test to test; a dynamic insulation system (66, 68, 70) prevents heat loss from the sample under test; an improved test based on the sensed temperature of the sample immediately after the heat is turned off detects the presence of tungsten forgeries; a compensated infrared sensor (138-146) eliminates the need for a direct contact temperature sensor; and tests are provided for determining various physical characteristics of an unknown sample. </p> |
