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We have considered the results of the analysis and estimation of systematic errors involved in the multimodel method for determining the thermophysical properties of solid materials. We have analytically obtained the condition that determines the upper limit of the reliably determinable thermal conductivity of the materials under study.Introduction. The multimodel method of nondestructive determination of the thermophysical properties (TPP) of materials relates to indirect measurement methods because not the very thermophysical quantity is measured directly in the course of an experiment, but rather thermograms (time dependences of temperature) are recorded [1][2][3]. The method is based on analytical solutions of the mathematical models of heat transfer processes occurring in a body under study exposed to the action of a constant strength round heat source (with the use of data for various portions of a thermogram [4,5]).Multimodel Method for Nondestructive Determining the Thermophysical Properties of Materials. The method is based on the following assumptions: 1) on a thermogram there are portions for which a highly accurate coincidence with the results of computational experiments by analytical models is ensured. Moreover, corresponding to these portions (Fig. 1, portions II and IV) there are the thermal regimes of the experiments that came up to the regularization stage (in what follows these portions will be called working);2) for the working portions there exist expedient computational relations allowing one to unambiguously determine the values of thermophysical properties depending on the parameters of the analytical function that describes the thermogram within the given interval.According to the method of [1, 2, 5], portion II of the thermogram (Fig. 1) is described by the equation of the form

Among the noises occurring in industrial buildings, the impulsive noise affects the human body most detrimentally. Since the impulse noise is not constant in time, when choosing and designing means of reducing it, the changes of spatial-temporal characteristics of sound energy should be calculated after emission by a source of sound pulses. In order to assess the energy characteristics of impulse noise, the article proposed a calculation method based on the ideas of the diffuse character of sound reflection from fencing. Developing the method, a statistical energy model was used, which describes the distribution of reflected energy in closed air volumes in time and space. A direct difference method is proposed to implement the computational model. The principles of the construction of the calculation method are stated and its accuracy is estimated. The assessment of accuracy was carried out by comparative analysis of the calculated and experimental data obtained in the buildings of complex geometric shapes under the action of a pulsed noise source in them. It is established that the calculated decreases of sound pressure levels in time at the calculated points are in good agreement with the experimentally determined decreases, and the error in the calculation of the levels does not exceed 2-3 dB. The obtained accuracy of the calculations is sufficient for the design of building-acoustic means of impulse noise reducing. The method allows making calculations in rooms with any complex space-planning parameters.

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Process equipment placing in industrial premises leads to essential change of room acoustic characteristics: mean length of sound rays' free runs, reverberation time and mean absorption factor in a room. The changes influence distribution of the reflected sound energy in premise volume. Failure to take account of the given circumstance results in errors at definition of sound pressure levels and an estimation of efficiency of building-acoustic measures of noise abatement. In the paper the results of computer modeling of acoustic processes in premises with the process equipment are considered and influence of the equipment on a sound absorption indoors is analyzed. The computer simulation is carried out on the basis of the ray tracing method with taking into account rays' energy distribution in a room. It is shown that such approach allows determining objectively the integral acoustic characteristics of industrial premises, takes into account influencing to them the room parameters, the presence and scattering characteristics of the equipment and makes more accurate the equations putting into engineering practice.