Throughout the history of human exploration of outer space, work is underway to reduce the cost of bringing cargo into space. One of the technically feasible solutions to achieve this is the use of smallsized reusable aerospace vehicles. As the new thermal protection materials are developed, they are employed for the construction of the reusable aerospace vehicles (RSV). In this paper, the assessment is given of the possibility of making RSV wing leading edge from an Al2O3 fiber based heat-resistant porous ceramic. The main advantages of using such material are its relatively low values of thermal conductivity and density, which makes it possible to improve weight characteristics of the RSV. The material of the support structure is heat-resistant carbon fiber reinforced polymer (CFRP). Due to the porous nature of such thermal protection system (TPS), it is necessary to consider the effect of air pressure on the thermal conductivity of the material. Therefore, a computational mathematical model is proposed that allows one to take into account this dependence of thermal conductivity on temperature and pressure for the wing edge porous TPS of an aerospace vehicle, during its re-entry in the atmosphere. Based on the temperature field inside the leading edge, the minimum thickness of the thermal protection coating was determined so that the support structure temperature stays within its maximum permissible operating range. It is shown that the Al2O3 heat-resistant porous ceramic can provide the required thermal protection, so that the maximum temperature of the composite support structure does not exceed 250 °C on the entire re-entry flight path.

This article examines the conditions for reliable clamping of workpieces in fixtures, which are one of the main elements in a technological system. In order to calculate clamping error of workpieces in fixtures empirical relationships of nonlinear character are currently used. Values of the coefficients included in these relationships are only specified for steel or cast iron workpieces. The paper presents the technique for calculating the clamping error of workpieces mounted on fixture supports with spherical heads, which allow to achieve the greatest locating precision. Practically, this technique allows to perform the calculation of the specified error for different fixturing conditions of workpieces. Mathematical relationships for calculation of the error for machining workpieces of any modern engineering materials are obtained. Comparative analysis of the obtained relationships for the standard conditions of force contact of the support elements with the workpiece showed that the clamping error calculated in accordance with the obtained relationships and taking into account friction forces in the contact area of the supports with the surface of steel workpiece almost coincides with the error determined by formulas given in the reference literuture. It is demonstrated that with the decrease in clamping force the elastic displacements at the interface are negligible and the clamping error can be calculated through a simplified relationship.

Recently in practice of engineering hydraulic structures spillways with a longitudinal-circulating flow are applied. The distinguished properties of longitudinal-circulating flows are a unique example of compatibility of flow type with technological purpose of a spillway structure. The hydraulic characteristics of flow (throughput capacity, velocity distribution, pressure distribution, cavitation analysis, etc.) are determined on the basis of the calculation methods developed in the above studies, namely for: longitudinal flow using the known standard calculation methods [1]; longitudinal-circulating flow interacting with solid boundaries of spillway [1-4]; longitudinal-circulating flow in the form of a swirling stream in the aquatic environment or in the air [2; 3]; the flow arising from the interaction of unidirectional longitudinal-circulating flows [4; 5]; the flow arising from the interaction of oppositely swirling coaxial flows [3]. In this paper, the authors consider the longitudinal-circulating flow of viscous incompressible fluid in a closed channel and in a jet using a velocity wurf linking the three components of velocity U , V and W .

The paper is devoted to a numerical method for solving the optimal control problem. The main approach to the numerical solution of the optimal control problem is the reduction of the optimal control problem to the problem of nonlinear programming and its following solution by classical gradient optimization methods. For this purpose, optimal control problem, which is a problem of searching time-dependent function, is replaced by the problem of searching of control values at discrete instants of time. An increase in the number of sampling points increases the accuracy of function approximation, but at the same time increases the dimensionality of the search space in the non-linear programming problem. In complex problems of non-linear programming with an unknown topology of the objective function, the statement that using classical gradient methods ensures finding a solution is not justified. The optimal control problem after the discretization and other modifications is often transformed to a non-linear programming problem with a non-unimodal objective function for which gradient methods are not applicable. In this paper we propose to solve the optimal control problem by evolutionary algorithms that do not use gradients and are able to find solutions of problems with nonunimodal objective function. The paper presents the modern evolutionary algorithm Grey wolf optimizer. The problem of the optimal combat turn of the aircraft is considered. In this problem the mathematical model of the control object is described by a system of seven ordinary differential equations. Also constraints on the value and rate of change of control are given. It is experimentally shown that the evolutionary algorithm Grey wolf optimizer successfully solves this optimal control problem.

The relevance of the work is attributed to the possibility of engaging stocks of low-grade ores in mining, which is prevented by insufficient knowledge of the leaching process. Preparation of ores is carried out without accounting for all properties of minerals and modes of solution movement, which increases the cost of mining, increases the loss of useful components and degrades the technicaleconomic criteria. The aim of this work is to systematize the theory and practice of using leaching technology with optimization of the mineral resources utilization criterion, accumulated in the uranium-mining industry of the USSR. The article contains the description of the processes carried out in mining practice for the first time. Results. The fundamental distinction of the technology of leaching metals from ores as changing phase of metal explicitly in-situ is formulated. The features of layout design and the use of preparatory and development workings on the conditions of their reuse in the process, crushing by condition to ensure penetration of the reagent solution into the ore piece, irrigation as a process determining the economic purposefulness of the technology, collecting solutions and preventing leakage for industrial sanitation and human health are described. The features of intensification of the drill-and-blast leaching process by deformation of the volume of leachable ore with of explosive gases and stress waves are distinguished. Examples of accounting for special features of ore deposits leaching in the USSR are presented. The practice of monitoring the completeness of leaching by excavation workings on leached ore is described. A brief description of the benefits of leaching technology in cleaning up the stocks lost by the traditional technology is given. Conclusion. It is noted that underground leaching may take priority positions in mining, so development of scientific basics for its implementation is one of the most important tasks of mining production, accomplishing which affects the creation of highly productive and waste-free systems of extraction of useful minerals from the subsoil. The experience of the ISL allows to create a methodological basis for expanding the scope of metal leaching technologies. The article contains the description of the processes carried out for the first time in mining practice.

The problem of cost-effective oil production from carbonate reservoirs becomes more and more important every year due to a decrease in oil reserves in terrigenous reservoirs. Oil extraction from carbonate reservoirs is always associated with the low filtration properties of the rock matrix and the dense fracture network presence. One of the most effective methods at this development stage for carbonate reservoirs is the non-stationary drainage technology. The development of non-stationary deposit drainage technology by determining the effective action time with different work periods and well accumulation, due to deformations in the fracture system, will allow reducing wells watering percentage. As a result of fluid flows redistribution in the formation, unprocessed areas are attracted by capillary impregnation. An important stage in the application of non-stationary action is the study of oil optical properties. To assess the quality of the reserves involved in the development, laboratory studies of the deposit non-stationary production efficiency of the Romashkinskoye oil field were carried out. The investigations were carried out using a spectrophotometer and a chromatograph. The influence of non-stationary selection on the wells operation dynamics and on the final ORC was determined.

Shortage of chromite raw materials in Russia at present time encouraged the use of methods, which have not been previously used in exploration and prediction of ore bodies. Chromite deposits of the Urals are characterized by a very complex structure. For prediction of the declination of ore bodies it is possible to use the observed relationship between the structural elements of ultrabasites and the preferential orientation of the axes of the optical indicatrix of olivine. In the majority of cases the Ngaxis of the indicatrix are parallel statistically to the linearity of chromespinelide. An important structural element is the linearity, which is presented by subparallel chains of isometric grains of chromespinelide or elongated grains of chromespinelide oriented in the same direction. The results of microstructural analysis of the enclosing rocks and measurements of the preferential orientation axes of the optical indicatrix of olivine on Yujnopogureyskoe deposit has allowed to predict the decline of the ore bodies. Information about the spatial position and morphology of the ore bodies allows effective planning of the exploration work.