Scientific directions from IPMP NASU

It was proved for the first time that rock mass is capable to create the dissipative structures (DS), which self-organize and facilitate their irreversible movement during accumulation of the damage to spend minimum potential energy for the same amount of the irreversible integral movement of the rock mass (Nazimko & Zakharova, 2017; Zakharova, 2018). These structures are triggered by random fluctuations of thermodynamic parameters such as pressure, temperature or volume. DS are a product of both the close interaction of adjacent blocks or ground fragments and the distant cooperation of the block clusters (Griniov et al., 2017). The ground fragments create short-lived clusters that move as an entirely aggregated body, which may eventually reintegrate into other clusters and blocks during progress of the irreversible ground moving.

DS facilitate the accumulation of degrees of freedom for a ground body to separate from the stable rock mass and develop a landslide or roof sag and even a fall in an underground opening. These patterns of nonreversible ground motion can be unveiled with incremental fields of ground movement. These increments should be as small as possible however not to be less than the error of measurement.

The patterns of ground irreversible movement and the dissipative structure vary in space and in time. The adjacent blocks and clusters promote their cooperation giving the way one after the other, moving in turn, alternatively. The anti-phase pattern of incremental block movement prevails and is the most important peculiarity of the irreversible behavior of the ground and a rock mass. A block delayed when the adjacent block accelerated and vice versa, what demonstrates the close interaction of the ground fragments.

An apparent distant cooperation manifested during the development of a damaged zone around an underground roadway when this zone sequentially expanded to all direction not at the same time but in turn. Possibility of synchronous active irreversible movement of surrounding ground in all directions (from the roof, sides, and floor) is negligible because it is not consistent with the second law of thermodynamics.

The close interaction and distant cooperation of the rock clusters create such patterns of DS as rotors, torrents, sources and sinks.

It is very important to investigate how patterns of DS and their evolution depends on the rate of loading. Preliminary researches indicate that on one hand, increase of the rate multiplies number of DS patterns. However on the other hand, high rate of loading shifts the path of loading and demands more energy (specific energy, reduced to the volume of the ground) to produce the same amount of irreversible ground movement.Basic investigation relied on experimental works due to actual measurements of irreversible ground movement in situ. Computer simulation will be another tool to investigate irreversible ground movement. This is the aim of future proposed investigation.

(Responsible: D.Sc. Prof. Victor Nazimko)

The main purpose of this project is to establish laws of joint mass transfer of methane and water in the fractured-porous structure of the coal-rock massif at micro- and macro-scale levels;heat transfer at self-heating of coal seams and coal-massifs, burning of methane in mine workings; determination of the roles of filtration permeability, heat transfer to the mine workings wall, its geometry, crack resistance, activation energy of surface diffusion, methane concentration in the mine workings in the studied processes.

The application of the methods of thermodynamics of irreversible processes and statistical physics is relevant for the reason that reveals the deep mechanisms of joint mass transfer of fluids in coal seams and hydrocarbon arrays, as well as to adequately describe the thermal regime of coal seams lying at great depthand waste heaps. This will allow us to scientifically substantiate the prediction of underground fires and establish criteria for the ecological safety of waste heaps.

Calculations of critical gas dynamics of a mixture of methane and oxygen in mining operations on the basis of the concept of non-isentropic flow will reveal what will be the role of concentration of methane in production and the role of heat transfer from gases to production walls in the passage of combustion of methane, which will allow a more reliable justification.

Recently, in connection with the depletion of traditional fuel sources, non-traditional sources, primarily coal gas and shale gas, are becoming important. The method of hydraulic fracturing of coal and rock formations is used for their production. Our previous work on the theory of the evolution of trunk cracks can be developed in this direction in the case of initially gas-filled cracks. Calculations of the development of such cracks, taking into account the filtration of both water and gas, which is displaced through the walls into the surrounding rock, will allow us to optimize the technology of fracturing and further utilization of mine methane.

(Responsible: D.Sc,. Prof. Eduard Feldman)

The main purpose of this research area is to systematically study the role of various control parameters in the formation of ferroelectric domain structures under conditions where, due to rapidly cooling, the crystalline sample is in a very non-equilibrium state and becomes particularly sensitive to too small external actions.Establishing physical regularities of the influence of external thermal, mechanical and electrical actions on the relaxation kinetics in ferroelectrics will allow optimizing the processes of obtaining high-quality precision domain structures in order to improve the nonlinear optical, electro-optical and acoustic characteristics of ferroelectric samples.

Upon rapid cooling of the sample from the high-temperature region (paraelectric phase) to the low-temperature one (ferroelectric phase), the crystalline sample turns out in the thermodynamically nonequilibrium state. As a result, this is accompanied by the spontaneous arise the nuclei of domains in spatial and random places of the sample. The high sensitivity of such a system to even very weak external influences opens wide opportunities to control the process of domain structure formation. However, a thorough study of fundamental aspects of ordering process is necessary to develop the practical recommendations for obtaining the domain structures with a given configuration. Therefore, the issues to be addressed within the proposed area, namely how external thermal, electrical and mechanical effects affect the kinetics of domain structure relaxation, are extremely relevant at the present time.

In order to achieve this goal, it is expected to obtain evolutionary equations describing relaxation processes. Due to the random character of the initial conditions, it is assumed that they will be processed within a statistical approach using correlation theory. Ferroelectrics of the displacement type, such as barium titanate, lead titanate, lithium niobate, are the most common and demanded in the modern domain engineering and will be used as model objects.

The results of the studies to be obtained will allow a more accurate quantitative description of the dynamics of non-equilibrium ferroelectrics of different types. We expect that these results will allow us to develop scientific basics and to propose the new methods of influence the domain structures, which are aimed at improving the physical properties of ferroelectric crystals and should contribute to the successful solution of technological problems of modern photonics.

(Responsible: D.Sc. Leonid Stefanovich)