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Purpose. To evaluate the change in free energy in the transition from the nonequilibrium state of the rock to the equilibrium. This process implements the process of dynamic brittle fracture on the structural defects of the rock as a microinhomogeneous medium.Methodology. It included conducting, within the framework of statistical thermodynamics, a series of experimental studies on the density and velocity of propagation of longitudinal and transverse acoustic waves in sandstone samples under different loading conditions.findings. According to the experimental data on the velocities of propagation of longitudinal and transverse acoustic waves for a number of sandstones at different loading modes, the values of mechanical and thermodynamic parameters characterizing the state of rocks are established. A comparative analysis of the frequency dependences of free energy on the value of the Poisson ratio is carried out. originality. A model of a thermodynamic system is proposed that describes the energyactivated process of transition of rock from a nonequilibrium state to equilibrium during external perturbation by surface acoustic waves. The possibility of estimating the degree of slow dynamic destruction by the Debye temperature is revealed. The mechanism of dissipation of internal energy on structural defects of the system, with the transition of its part into thermal motion of structural elements, is substantiated.Practical value. The technique for investigation of thermodynamic state of nonideally elastic rocks by methods of nondestruc tive testing is developed. The correlation between the mechanical parameters of the rock and the characteristics of the process of its transition from the nonequilibrium state to the equilibrium is established.

A problem of estimating the movement and orientation of a mobile robot is examined in this paper. The strapdown inertial navigation systems are often engaged to solve this common obstacle. The most important and critically sensitive component of such positioning approximation system is a gyroscope. Thus, we analyze here the random error components of the gyroscope, such as bias instability and random rate walk, as well as those that cause the presence of white and exponentially correlated (Markov) noise and perform an optimization of these parameters. The MEMS gyroscopes of InvenSense MPU-6050 type for each axis of the gyroscope with a sampling frequency of 70 Hz are investigated, as a result, Allan variance graphs and the values of bias instability coefficient and angle random walk for each axis are determined. It was found that in the output signals of the gyroscopes there is no Markov noise and random rate walk, and the X and Z axes are noisier than the Y axis. In the process of inertial measurement unit (IMU) calibration, the correction coefficients are calculated, which allow partial compensating the influence of destabilizing factors and determining the perpendicularity inaccuracy for sensitivity axes, and the conversion coefficients for each axis, which transform the sensor source codes into the measure unit and bias for each axis. The output signals of the calibrated gyroscope are noisy and offset from zero to all axes, so processing accelerometer and gyroscope data by the alpha-beta filter or Kalman filter is required to reduce noise influence.

The paper deals with its own oscillations of a rectangular rod with a cross section of a rectangular shape. The method of determining real part of Young's dynamic modulus and tangent of mechanical loss of samples in the form of rods of a number of polymer materials by means of resonant vibrating-reed method are proposed. Experimental setup, algorithm and software for determining the amplitude of the sample oscillations are developed. The accuracy of measurements was determined and a comparative analysis of results was performed with data obtained by other methods.

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