Search

The study analyzes the influence exerted by the body, guide and their materials on the pull strength of electromagnets in electromagnetic hammers. The pull strengths of electromagnets without positive and negative poles are evaluated.

The researchers analyze energy processes running in an autonomous electric power system consisting of a synchronous permanent magnet generator and a semiconductor converter. Current, voltage and capacity of key components of the system are evaluated, and the system operation modes are determined for the variable magnitude and character of applied load at the constant voltage output frequency. Parametrical law is proposed to control semiconductor frequency converter serially connected to load and generating reactive power. The influence of the converter on the basic design parameters, energy specifications of the synchronous generator and the system as a whole are evaluated.

Under consideration is feasibility of voltage stabilization in permanent-magnet synchronous generator with variable frequency in self-contained systems of power supply. The method of stabilization is based on varying speed of rotation of generator shaft. The authors have derived analytical expression for regulating characteristics and determined required ranges for rotational frequency variation at preset parameters of generator and loading. The symmetry conditions are found for a regulating characteristic relative to rotational speed change.

The article analyzes processes running in an oil pool under contour water flooding and resulting in formation of bypassed oil. Based on stability criteria, the authors discuss destabilization of the residual oil pockets by vibration so that the bypassed oil becomes proved & developed.

The paper proposes the analysis of three design and control scenarios for the system intendeded to generate the variable-frequency and constant-voltage electric energy on the basis of a synchronous generator and a paralleled semiconductor converter. The research scientists demonstrate the stabilization of the synchronous generator voltage, evaluation of basic electrical parameters, and the relationship between them and operation modes of the system.

The processes in the system composed of a continuous magnet synchronous generator and a three-phase bridge back emf rectifier are under analysis in this article. Such systems are usable in self-contained facilities to charge accumulation cells in mines and open pits. The authors determine possible regimes of the systems under varying rate speeds of synchronous generator shaft and altered commutation delay angles of the controlled rectifier, derive analytical expressions for determining parameters of the analyzed system, and find generated power limit.

The thermal parameters of the resistors of self-synchronization included in the excitation systems of turbo- and hydrogenerators are studied.

The paper explains a number of phenomena that are observed in the surface vibrational treatment of oil and gas reservoirs based on the thriving theory of pendulum waves, e.g., a ring-shape response of a productive stratum and a time lag in the response, seismic luminescence and its spectrum, etc. The authors give data on velocity groups of pendulum waves in stressed block hierarchy of rock masses and substantiate the choice of the wave velocity group to be generated by the powerful surface vibro-sources designed at the Institute of Mining. The theoretical and phenomenological formulas given in the paper are of assistance in the development and improvement of the surface vibrational technologies for the enhancement of oil and gas recovery.

It is suggested to replace the double-winding transformer of the excitation system of a synchronous machine with a valve-side winding rated for the total forcing voltage and rated current by a three-winding transformer with two valve-side windings, i.e., working and forcing. In the proposed transformer, each of the windings is connected to its own converter bridge circuit and the voltages are summed up during field forcing, which allows the power of the rectifying transformer to be decreased, the shapes of the current and voltage curves at the converter inlet and outlet to be improved, transformer losses and voltage crests on the rotor, and inverse voltages on the thyristors to be reduced, etc.

It is established experimentally that, in block geomedia, under conditions of sustained (months) uniaxial loading, the normal tension cracks can appear and develop under the action of stresses which are less than the ultimate strength in uniaxial compression of the corresponding geomaterial samples by an order. The features distinguished in the experiment on failure of one-dimensional block model of geomedium are compared with the results of visual and instrumental observations of failure character of the ore masses of the Talnakh-Oktyabrsky deposit.

Development of construction principles and creation of automated systems for physical modeling of the block geomedium behavior in the varying unequally component stress field are considered currently as one of the strategic problems in nonlinear geomechanics. The scheme of stand for physical modeling and measuring-computational equipment oriented to the solution for fundamental problems of geomechanics are presented.

The purpose of this paper is the examination of problems involving energy conversion in electromechanical converters with allowance for the distribution of magnetic energy in various parts of the magnetic system and simultaneous mutual exchange between three forms of energy - the source of supply, the magnetic energy of the system, and mechanical work.

1. The reduction in the draw characteristics of electromagnets with neither one nor two poles with respect to those of a two-pole electromagnet does not exceed 15–20% in the region of preliminary block insertions to 0.75 LW in the winding. In this case, the reduction in the integral work of the electromagnets does not exceed 20%. 2. When the winding is split into sections and they are mutually separated, the difference in the pulling force between two-pole and poleless electromagnets decreases for the same block insertion in the winding. 3. Conditions for which the pulling force of an electromagnet with a single pole on the side of the effective gap will be higher than that of a two-pole electromagnet, and the pulling force of a poleless electromagnet will be higher than that of an electromagnet with a single pole on the side of the ineffective gap are determined and proven experimentally. 4. The interrelation between the relative reduction in the pulling force of an electromagnet ΔF/F0 and the relative lengthening of its winding ΔL/LW0 is established.