Ultimate state criteria and strength characteristics of the rock massifs being undermined repeatedly

Methodological approaches to the selection of ultimate state criteria and strength characteristics of the repeatedly undermined rock massifs were developed. These approaches were designed to provide parametric support to the geomechanical modelling of the massif stress-strain state and the mining systems of the Starobin potash deposit mine fields planned for the additional mining of the mineral reserves left. It was established that a complex criterion must be used to study the massif ultimate state. Determination of such criterion can be carried out using the developed approaches. The first approach is to select several criteria that evaluate the massif ultimate state by certain types of the massif stress-strain state. These criteria are the following: the criterion of the maximum normal stresses, criterion of the maximum linear strains, the criterion of the maximum shear stresses and the Coulomb–Mohr failure criterion. The second approach is to construct an integrated failure state criterion for materials whose ultimate tensile and compressive stresses differ significantly. In this case, parameters characterizing the type of stress state and properties of the material are introduced. These parameters together determine the destruction character – tear or shear. To describe the rocks behavior in the extreme strength stage of deformation, it is proposed to apply deformation theory of strength using the developed strain failure criterion. When calculating the strength characteristics of the repeatedly undermined rock massif, it is recommended to use a structural attenuation coefficient as the product of several factors, taking into account various types of disturbances in the primary undermined massif and the time factor. The Coulomb–Mohr strength condition is recommended to be used taking into account the composite structural attenuation coefficient. Dependencies have been developed to describe the change in the strength characteristics of rocks in the undermined massif, considering the attenuation coefficient.

Determination of the Optimal Parameters of the Jet Aeration

To ensure effective aeration of the biological wastewater treatment process, easy-to-operate and not too energy-intensive units are needed. Jet aerators have such capabilities. In this study, the authors searched for the best hole shape for the aeration nozzles. It was determined that a nozzle with an elongated hole has the largest size of the actively aerated zone. Experimental studies of nozzles of a diameter of 56 mm with nozzles of elongated shape showed that the best characteristics of mass transfer are provided by nozzles with a total area of holes of 356 mm2 at a flow rate of 10 … 12 m/s. For practical calculations, an equation was obtained for the dependence of the oxygen transfer coefficient KLa(20) on the complex criterion vn, and a method for calculating aeration units was developed, which is applicable for aerators with elongated holes.

CRITERIA OF SAFETY CONDITION ASSESSMENT

The article is the second in a series of articles, united by a single theme of improving the organization of the country’s security management system. The article is completely based on the previous article “Formalization of safety assessment and management” and is a continuation of it. Accordingly, the article uses a unified approach to improving the organization of the management system, the same terminology and notation. It has been determined that the safety assessment significantly depends on the operating conditions of the control object. The approach to formation of structure of criteria of an estimation of a condition of safety on the analysis of full group of conditions of functioning of object of protection and the account of threshold values of complex criteria of an estimation – positive and negative potentials is offered. The possible structure of formation of a complex criterion of safety assessment is considered. The effectiveness of the proposed safety assessment system is based on the formalization of the signs of threats and risks through the analysis of potentials relevant to the object of management. Representation of the object of control in the form of a formal model and the use of a safety chart allows to analyze the safety status on formal grounds and analyze using the proposed comprehensive criterion. The formalization of the safety assessment procedure and the quantitative interpretation of the potentials allow the maximum use of computer information processing in order to timely objectively identify threats, conditions and risk areas.

ВИДИ МЕТРОЛОГІЧНИХ ХАРАКТЕРИСТИК І СКЛАДУ РОБІТ З ЇХ ВИЗНАЧЕННЯ НА ОСНОВНИХ СТАДІЯХ ІСНУВАННЯ КОМПОЗИТНИХ КОНСТРУКЦІЙ АГРЕГАТІВ ПОВІТРЯНИХ СУДЕН ТРАНСПОРТНОЇ КАТЕГОРІЇ

It is shown that the development of the concept of metrological support for the creation of composite structures of aircraft aggregates of the transport category and their support at all stages of the existence of an aircraft should be based on the formation of a complex criterion for the effectiveness of the use of polymer composite materials. It is noted that the effectiveness of a structure made of polymer composite materials is provided by various methods, methods and technical means of metrology. The structure of a complex of studies aimed at developing the concept of metrological support is discussed, the first point of which is to analyze the types of metrological characteristics and the scope of work to determine them at the main stages of the existence of composite structures of aircraft aggregates of the transport category. Based on the analysis of numerous publications on the problem of metrological support of the main stages of creating technical products, the main types of measurements of the metrological characteristics of composite structures of aircraft aggregates of the transport category have been established, and the composition of the nomenclature of works on metrological support of the main stages of the existence of these structures has been determined. 12 main types of measurements of parameters have been identified, on which the whole variety of production physical quantities and the description of the properties and characteristics of structures of aircraft aggregates made of polymer composite materials are based. The composition of the main works on the metrological support of the four stages of the existence of the aircraft is revealed: design, production, operation and disposal of composite structures formed into systems of sequential blocks for performing these works. It is shown that the tasks of metrological support at the facility manufacturers should be solved during the technological preparation of serial production and testing of the installation series of products, and also take into account the peculiarities of aircraft operation and disposal of composite structural elements in terms of work safety and economic efficiency of their results. An enlarged sequence has been established for organizing work on metrological support for measuring the properties of composite structures of aircraft aggregates at aviation enterprises. The results presented in the first approximation provide a solution to practically important aspects of the problem under discussion.

New Methods Used for the Smoothing of the Three-Dimensional Flow Behind the Turbine Nozzle Cascade

To smooth the parameters of the three-dimensional flow behind the nozzle cascade new methods were suggested that allow us to sustain the flow rate, stagnation enthalpy and the axial projection of the moment of momentum for initial-, nonuniform and averaged flows. It was shown that the choice of the fourth integral characteristic (the kinetic energy, the entropy and the quantity of motion) has no particular significance because it has no effect on the complex criterion of the cascade quality, i.e. the velocity coefficient-angle cosine product that characterizes the level of the radial component of velocity. The minimum values of the velocity coefficient and the cosine angle satisfy the method that allows us to sustain the quantity of motion during the smoothing and the maximum values of the specified nozzle characteristics satisfy method 2 that enables the entropy maintenance. To evaluate the aerodynamic efficiency of the nozzle cascade the preference should be given to method 1 that enables the kinetic energy conservation and the velocity coefficient allows for the precise determination of the degree of loss of the kinetic energy that is equal to 3.6 % as for the example given in the scientific paper. As for method 1, the kinematic losses in the cascade are defined by the angle cosine that characterizes the level of the radial component of the velocity behind the cascade. For the example in question, kinematic losses are equal to 1.9 % and the complex criterion of quality equal to 0.972 corresponds to the overall losses of 5.5 %. It was suggested to use the velocity coefficient and the two angles of flow as integral cascade characteristics. The use of these characteristics enables the correct computations of the efficiency factor for the stage within the one-dimensional computation. The incisive analysis was performed for different methods used for the averaging of the parameters of the axially asymmetric flow behind the nozzle cascade. It was suggested to neglect the flow rate factor in the case of thermal computations done for the turbine stage.

Loss Assessment of Qualitative and Quantitative Composition of The Middle Class in Terms of Sustainable and Digital Development

The article studies the trends of quantitative changes in social class in Ukraine as an important factor of sustainable socio-economic development. The use of a complex criterion for determining the core of the middle class in the population structure is substantiated. It takes into account the level of income, self-identification, and qualitative characteristics. The article proves the hypothesis of conformity of the distribution of households by average per capita equivalent income to the theoretical log-normal distribution. The paper provides the quantitative characteristics of the impact of digitalization on the size of the middle class, determines the consequences of distribution of information technology for its existence. The main directions and tools for influence are proposed to ensure the conditions for the formation, development, and growth of the middle class in modern society, and to achieve a high level of economic development and welfare of the population.

Method for synthesis of matching devices for broadband radio engineering systems with unstable load impedance based on the method of real frequencies

The aim of this work is to develop a method for the synthesis of matching devices for broadband radio engineering systems with varying impedance in different operating conditions. To achieve this goal, a criterion (complex criterion) is proposed for minimizing the value of the modulus of the sensitivity invariant of the reflection coefficient function to a change in the load impedance with restrictions on the square of the deviation of the power transmission ratio from a given level. It is proposed to use a combination of methods of real frequencies together with the shown complex criterion, which made it possible to implement an effective approach to the synthesis of matching devices for broadband radio engineering systems with an unstable load impedance. To verify the approach, a matching device was synthesized, which made it possible to reduce the loss of the power transmission factor level transmitted to the UHF/VHF antenna of the AD-44 / CW-TA-30-512 range when it is located in various operating conditions by at least 50 % in relation to losses obtained with a standard matching device.

A Theoretical Analysis of Profile Conformance Improvement Due to Suspension Injection

This study is focused on a solution for the problem of suspension penetration in a porous formation. Such a solution forms the basis of injection profile diversion technology for oil reservoir sweep improvement. A conventional model of deep-bed suspension flow was used to describe the suspension injection process. The suspension slug was followed by water injection, and the inflow injection profile before and after treatment was investigated. For the first time, the criteria that determine the effectiveness of the inflow profile improvement process are introduced. The effect of the suspension filtration coefficient on the particle penetration depth was studied. A specific filtration coefficient value for the maximum penetration depth was achieved. The obtained analytical solution was generalized on multi-reservoir strata with poor interlayer crosslinking. The efficiency of profile conformance improvement was described by the differences in the root-mean-square deviations of the inflow velocities in interlayers from mean values before and after the treatment. It was shown that the complex criterion of suspension treatment efficiency should include a reduction in total injectivity. An increase in suspension slug volume improves the injectivity profile but decreases the total injectivity of an injector.

Experimental results on the developing personal security skills of future border guard officers

The purpose of the article is to verify the effectiveness of pedagogical conditions for the development of personal security skills of future border guards. Various diagnostic methods, introduced in the research, allowed to prove the effectiveness of the application of the developed pedagogical conditions and to adjust the methods of their further implementation. Much attention was paid to the comparison of results in the control and experimental groups separately for each criterion, as well as for the complex criterion. The authors generalized, systematized and theoretically analyzed the results of experimental work. The analysis of the results of the experimental research testifies to the effectiveness of the pedagogical conditions developed and implemented in the educational process of the National Academy of the State Border Guard Service of Ukraine (NASBGSU) for the development of personal security skills of future border guards.

Detection of anthropogenic objects based on the spatial characteristics of their contour in aerial image

In this paper, an analysis is performed for the spatial characteristics of the contours of aerial images that are homogeneous in brightness to determine the parameters that make it possible to identify anthropogenic objects with a higher probability. A complex criterion is proposed for the regions, which homogenous in brightness and an algorithm for detecting anthropogenic objects, which takes into account its area, the ratio of the total length of long contour fragments to the total length of the contour, the concentration of corners and endpoints of the contour. Also, when deciding on anthropogenicity, the particular characteristics of the contour of a homogeneous segment are used, depending on the number of long fragments of the contour. Using the proposed criterion, an algorithm of searching anthropogenic objects based on the analysis of contour elements (its shape, size and concentration) is developed. The proposed algorithm allows reducing the probability of skipping the anthropogenic object in comparison with the spatial anomaly search algorithm.