Vol 20, No 2 (2019)

The ballistic problem of on-orbit space serving system configuration design for active Globalstar satellites is considered. These satellites are moving in orbits with close altitudes and inclinations but with significant difference in longitude of ascending node (more than 10 degrees). The onorbit space servicing system is a system of base orbital stations for servicing the given array of the satellites using the detachable orbital modules. The noted acoplanarity leads to high expenses of the total relative velocity (fuel) required for inter-orbit flights to serving satellites. The article provides an example of solving the design problem basing on the developed methodology of optimal serving planning using up-to-date algorithms of estimating energy costs of flights to serving satellites, that significantly decrease flight fuel costs. The problem of configuration design of space serving system as well as the problem of optimal serving planning has been solved basing on the analyzing the deviation map of satellites and orbital stations longitudes of ascending node. It is shown that proposed method allows to define the necessary amount and orbit parameters of orbital stations, the amount of detached orbital modules and total relative velocity, needed to service the given group of spacecraft.

Banded ferruginous-siliceous formations (FSF) are confined to the Precambrian basement of the Arabian-Nubian Shield within the central part of the Eastern Desert of Egypt. Gold mineralization is spatially associated with banded ferruginous quartzite, representing one of the most ancient manifestations of gold ore. The Precambrian rocks are combined into deposits complex of the Neoproterozoic Pan-African megacycle of the territory development. Banded iron-silicate rocks occur in sedimentary-volcanogenic rocks that were formed in the subduction trough zones, and are represented by metamorphosed ferruginous quartzites, jaspilites and schists. FSF show tectonic dislocations, shear cracks, and fracture cracks made by gold-quartz-sulphide mineralization. Promising for the identification of gold-bearing mineralization in the rocks of the FSF can be iron-silicate deposits with the occurrence of epigenetic hydrothermal activity as a result of activation of the submarine volcanism of the tholeiitic type.

The relevance of the study is explained by the need to improve technological processes with the increasing complexity of the development of ore deposits with an increase in the depth of development, the use of powerful technology and an increase in stresses in arrays of ore-bearing rocks. The need to minimize the risk of mining requires the development and use of tools for managing an array. The purpose of this study is to systematize information about the theory and practice of using the residual bearing capacity of destroyed rocks from the practice of underground mining to improve the methods used to control the geomechanics of ore-bearing arrays. The complex of research includes analytical, full-scale, laboratory and theoretical methods that are used to identify the phenomenon of the use of the residual carrying capacity of destroyed rocks. To achieve this goal information on the use of bearing floors made of intact and destroyed ores and rocks, as well as other materials, is systematized. A brief description of the scientific support of mining engineering tasks is given. The phenomenon of the use of residual bearing capacity of disturbed rocks in the structure arising in the mountain massif is characterized. A critical analysis of the concepts of array management is given. Considered alternative options for creating structures for solving problems of reducing the health risk of workers and improving the quality of ores. A new typification of structures using the residual strength of destroyed rocks is given. It has been proved that in underground mining there is an opportunity to realize the residual bearing capacity of the destroyed rocks to create structures with desired properties, which contributes to solving the tasks of labor protection and improving the quality of ores.

The main criterion for the performance of welds is the strength. The least durable are the corner joints used to perform various types of welded joints. In the literature, the methods of calculating the strength of welded joints with solid seams are considered in sufficient detail. Methods of calculation of connection interrupted sutures absent. In this case, the greatest difficulty is the calculation of connections using circular intermittent seams, which are often performed in welded drums and pulleys. They work on torsion. Therefore, the development of methods for calculating circular intermittent seams for torsion is quite important. Shear stresses in welds from torque are determined depending on the value of the polar moment of resistance of its dangerous section. When determining the polar moment of resistance of the dangerous section of a circular discontinuous seam, it was represented by a set of sections in the form of a sector of a circular ring. The method of calculation of the polar moment of resistance of the rotated dangerous section of a circular discontinuous weld, which takes into account the relative length of the weld areas and their number, is proposed, as well as the method of accurate and approximate calculation of shear stresses in the weld.

Article is dedicated to liquid flow measuring by acoustic flow meters. Manufacturers establish the allowable measurement range (nominal), within which the measurement error is minimal, that’s why their measuring span is limited, and the measurement error when operating in off-design modes is unacceptable. The basic task of this research is to expand the range of flow measurements of acoustic liquid meters. V.A. Fafurin and M.K. Galeev in their work “Calculation of the correction coefficient of the ultrasonic flow meter” have already considered the problem of measuring the flow rate of acoustic devices. In their study was presented a method for calculating the correction coefficient, which depended on the flow regime in the pipe. But this technology is applicable for change-less flow regime pipes. In this article, the authors propose to use a coefficient that has a functional dependence on the magnitude of the flow, obtained empirically. The article describes the stages of the study: the method of calibration of the device, methods of analysis and processing of verification data by PC, the algorithm of measurement system implementation in power engineering equipment, system performance check. The system presented in the article allows to expand the range. The proposed model will be useful for enterprises.

The need for reliable supports for locating and maintaining the equipment of cellular opera-tors is increasing every year. The classic version of the supports are lattice towers. At present, optimization of the parameters of lattice towers, which is one of the ways to improve the efficiency of their design and construction, is of great importance. The purpose of the work is chosen definition of a rational constructive form of lattice cellular communication towers. In the work, the calculation and analysis of the tower supports of a prismatic and pyramidal form are made with varying basic geometric parameters of the structure and the ratio of parameters between them. To create basic dependencies, numerical modeling methods are used. According to the results of a critical analysis of the literature on the calculation of lattice supports of high-rise buildings, the absence of recommended optimal values of the geometric parameters of structures and the relationship between them was established. The stress-strain state of the design models of lattice towers of a prismatic and pyramidal shape was assessed with variation of the main overall geometric parameters of the structures. To achieve the goal of finding a rational structural form of lattice supports, two rationalization criteria have been tested and applied - the simultaneous fulfillment of the requirements of both limiting states and minimization of the mass of the structure. The results of the study of lattice tower supports are presented in dimensionless parameters, which can be applied by the engineer when assigning the overall dimensions of the structure at the initial design stage.