The authors of the study work out the differential equations of motion of a vertical rotor model on an elastic-dissipative suspension, balanced by a ball-type automatic balancing device. Often, the cross-section of the cavity of the body of the automatic balancing device is rectangular and during rolling the balls have two points of contact, in one of which the balls slide along the surface of the cavity. To prevent the balls from sliding, the inner surface of the cavity of the automatic balancing device is made in the shape of a torus, which provides one point of contact. The forces of gravity and the forces of resistance to the movement of the correcting weights are taken into account, and the model is drawn up for both viscous and dry friction forces inside the body of the automatic balancing device. The obtained mathematical model of the rotor makes it possible to study the transient and steady-state modes of motion of the rotor system.
The paper analyzes negative impact of poor-quality electricity on the performance of electrical installations. Particular attention is paid to the ways to improve power quality under the conditions of industrial enterprises. Use of “individual” LC-filters to protect extra important electric drives; use of “group” devices to compensate negative effect of noisy electricity at a workshop level (power active rectifiers are meant with their potential integration into the available converters for the controlled electric drives); and to inhibit voltage distortions within the areas of their origination (i.e. the mains protection against the root cause) are possible means to solve the problems.
Purpose . Increasingly, in Ukraine, the construction of tunnels and metro requires special methods of work to reduce water saturation and increase the stability of soils and rocks of the surrounding massif. The variety of methods used in underground construction requires scientific justification, especially when special methods are close in direct and labor. The purpose of the scientific article is to analyze special methods of sinking vertical workings in difficult engineering and geological conditions to determine their scope . Methodology. Existing technologies for fixing water-saturated soils are used without sufficient scientific justification, in some cases without conducting a feasibility comparison of methods at the design stage. It should highlight the features, advantages and disadvantages of each of them and determine the boundaries of their application. To achieve this goal, three special ways of fixing soils were considered and analyzed: wall in the ground, artificial freezing of soils and jet-grouting . Findings . The advantages and disadvantages of three methods of fixing the soil are determined and the estimated cost of construction is calculated. It has been proved that the only technology that ensures safe penetration of trunks in difficult conditions when penetrating extended complex sections or in the case of penetrating very deep trunks is the technology of freezing soils. And in those cases when the thickness of the layers of weak watered soils is insignificant, the jet-grouting soil cementation technology becomes more efficient. The results of the analysis are the basis for the further substantiation of each of the methods from the standpoint of the stress-strain state of the overall system formed during the construction of underground facilities, in particular vertical workings for mine shafts . Originality. A comparative analysis of the three main special methods for constructing vertical workings made it possible to determine and scientifically substantiate the conditions for using each of them . Practical value. In the AVK-5 (3.5.1) software package, the estimated cost of all three methods of soil fixation was calculated. According to the calculation results, artificial freezing of soils is the most cost-effective .
