the Thermal stream in danii. Heat conductivity factor

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Heat conductivity factor. For measurement of factors of heat conductivity the method of a short-term linear source or methods of a needle probe and the divided core were used. For discussed materials the most exact results turn out at use of a needle probe, and all factors of heat conductivity resulted here, are measured by this method.

The needle Temperature is measured by means of traditional bridge Uitstona. The heating up element consists of a double manganous wire with resistance 450 Ohm/m which at a normal current force approximately 150 ma gives in a needle probe allocation of heat of an order of 10 Vt/m. Termistor is calibrated on the quartz thermometer when both probes are placed in rather steady thermal bath (±2 mk). In the course of measurements with needle probes of temperature are defined through everyone 10 with with accuracy ±3 mk.

Heat conductivity Factors are calculated by the standard way: with application of a method of the least squares to a linear part of curve dependence of temperature from time, and also on recently developed method of iterations of the least square-law inversion (Kristiansen and Balling, in the press). This last method gives the exact integrated decision of a problem of a cylindrical probe with an unsteady mode and allows to receive simultaneously heat conductivity factor, factor temperaturoprovodnosti and contact resistance from one zondovogo a signal. The standard deviation of each parametre can be besides, calculated.