Vol 24, No 1 (2016)

The author continues to research the information-systems time-scale synchronization to solve the problem of maintaining a single time at the power facilities of the regional grid company. The analysis of the algorithms and principles of the existing time protocols (NTP, SNTP, PTP) widely used in packet-switching data-communication networks is done to determine their satisfying the requirements and operation principles of the examined complex time-synchronization system. The paper presents the comparative characteristics of these protocols; conclusions are drawn taking into account the requirements of internal guidelines concerning the development of ICS to be met by the tasks of information-systems time-synchronization in power grid companies

The paper deals with the bearing capacity of heads with vertical contact grids (VGD). The main structural parameters affecting the strength properties of the head are found. A model of a VGD head is developed, its adequacy being checked. As the modeling result, the dependency of a contact-point ultimate load on the mass-exchanger design structural parameters is obtained. The maximum permissible distance between the gussets is determined which allows the head`s cost to be reduced while retaining its required strength.

The paper treats of the possibility of applying the mathematical tools and methods of classical automatic-control theory for analysis and synthesis of a company's manufacturing and business processes management. The description of a mathematical model of a company’s safety stock management in the form of discrete-time functions is given taking into account such factors as delays in delivery or unexpected increase in demand. The criterion of solving the problem of a company’s optimum inventory management is defined. This criterion takes into account various additional expenses caused by the stock increasing or decreasing in comparison with the demand value.

In this article the questions of synthesis of global assessments of innovative activity on an example of the Samara Region economy. As a method of systematic evaluation selected generic way of ranking based on the method of multi-criteria evaluation of efficiency Data Envelopment Analysis. The work implemented multi-criteria evaluation procedure and the ranking system of innovative activity in the region over the time interval. The information base for assessment procedures are the local state statistical indicators characterizing the scope of research and innovation at the regional level.

We discuss a new method of measuring the parameters (RMS of voltage and current, active and reactive power) by the instantaneous values of harmonic signals which provides their spatial-time division. In contrast to the known methods based on the formation of additional voltage and current signals and identifying the moments of signal zero crossing, the implementation of the method involves the auxiliary signals formation only in the voltage channel. A block diagram of the measuring system realizing the method is proposed. The analysis results of the method error caused by the deviation of the real signals from the harmonic model. The results obtained enable the selection of the appropriate hardware depending on the measurement-accuracy requirements.

A set of issues on modeling of electromagnetic and thermal processes in the induction heater for the formation of a magnetic field, compressing the melt and preventing the contact of silicon in the liquid phase with the walls of thermal insulation. In determining the inductor’s power and voltage frequency, the temperature-dependent nonlinear properties are taken into account. The design parameters which enable cooling to the solid state under induction heating conditions are searched for. To solve the problems of electromagnetic and thermal processes modeling used a finite-element formulation taking into account the nonlinearities and the fusion latent heat. Different realization variants of the inductor which enables covering the melt’s entire volume or its part in case of continuous movement after the silicon solidification are examined.

The method of calculating parameters for equivalent circuit of the induction motor with squirrel-cage rotor is developed. These parameters are necessary for the analysis and evaluation of the engine in various modes because background information of the manufacturer does not contain of these parameters. Nominal values of active and inductive stator and rotor resistances are derived from the three solutions of algebraic equations, which are based on the equations of nominal electromagnetic power, maximum electromagnetic power and the nominal reactive power dissipation. Resistance of circuit magnetization is determined from a consideration of the balance equation full power of this branch. Method of calculation of these parameters is represented as the block diagram.

The optimal laws of current change and speed of electromechanical positional system which provide minimum movement time for a demand movement and demand heat losses are defined in this article. The result is the formula for the time minimum during which the positional system performs the demand movement. The obtained armature current and speed extremals of positional electro drive in short-time duty can be implemented by using of high-torque direct current motors which are regulated by controlled converter with adjustable current-limit.

Creation of a new method of a reinforcement of a weld seam by an explosive doping at the expense of a high-speed penetration of particles. Definition of suitability of a method for a reinforcement of welded joints of rails. Creation of a method for raise of operation factors of rail welded joints. Use of an expedient of a reinforcement of a weld seam by means of effect of superdeep penetration the particles, implemented at the expense of a high-speed throwing of the discrete particles, accelerated by energy of explosion of an explosive charge. In the offered expedient for a throwing of particles the explosive charge is used superimposed. On an explosive charge bottom face the stratum of particles is superimposed. The explosive charge is disposed on an outside surface of a welded joint. On a rail joint surface the stratum of an easy material for fracture preventing is had. Experiments of a throwing of particles of wolfram on a steel (0.8 % С) are made. Concentration of the implanted particles of wolfram, hardness and microhardness of a steel is spotted. Usage of an superimposed explosive charge implements a throwing of particles by means of a shock wave at an angle. It provides more uniform concentration of the implanted particles. The offered method implements a high speed throw and the superdeep penetration of particles from solid materials and chemical combinations in metals. Raise of hardness and microhardness of steel (0.8%С) is attained. The offered method can be used for a mass reinforcement of welded joints of rails of railway tracks.

The paper concerns the optimization of the technology for repairing drill pipes by facing. The methods of tool joints repairing are surveyed. Various protective media while performing facing are analyzed. The selection of a preheating mode as well as the optimum thickness of facing layer is made. The physical and mechanical properties of repaired drill-pipe tool joints are assessed, analyzed the microstructure of the base metal is analyzed. The measures devised using the results of this research will guarantee the high quality of repaired products

The paper discusses the features of induction heating of bodies with sharply changing curvature of the surface, one should take into account the volume density of the electromagnetic field which manifests itself in the form of an electrodynamic interaction between the inductor and the slab. It results in strong vibration and noise exceeding health standards. These investigations enable making recommendations which take into account electrodynamic and vibroacoustic processes when designing rectangular inductors. The electrodynamic calculations were done using a numerical mathematical model constructed by means of the method of coupled circuits and the principle of possible displacements.