Vol 22, No 4 (2014)

This paper presents the problem of synthesis of the time-optimal system to control the process of induction heating of a workpiece for further chipless shaping with partial condition testing in conditions of the interval indeterminancy of the object characteristics considering the constraint on the state of maximum temperature. The obtained optimal algorithm of control with feedbacks is completed with special section on which the maximum temperature is maintained on the lowest acceptable level. Equations for the feedback coefficient calculation are shown and the structure of obtained closed-loop system is given. Numerical values of the feedback coefficients are calculated for the basic data of the induction heating process given as example, graphs of control input and temperature pattern are constructed.

Use of structural solutions to control of monoaxial and triaxial positioning system of satellite. One investigate the problem of application of intercontour regulators in a multivariable control system.The methods of synthesis of monoaxial and triaxial systems orientation. One solve the problem of improving the dynamic characteristic by introduction a correcting circuit for monoaxial coordination system; intercontour regulators introduced in gyroscopic channels of multivariable control system of positioning in three coordinates .

This paper deals with a new method of measuring the capacitive sensors parameters on the instantaneous values of transient processes on the sections of the measuring circuit that contain two exemplary elements. Unlike the known methods based on the capacity determination on individual instantaneous values of transient processes, the implementation of the method provides separate definition of both capacity and insulation resistance of capacitive sensor; this improves measurement accuracy of informative parameter. Typical block diagram of the information-measuring system that implements the method is given. The paper shoes the results of the analysis of errors that occur due to deviation of the actual transition process from the one put into the model. The optimal choice of the measuring circuit items in accordance with the requirements of accuracy and measurement time can be made according to the results obtained.

This paper deals with a new method of measuring the parameters of harmonic signals at their instantaneous values as the voltage passes zero point. Unlike the known methods based on the formation of additional voltage and current signals, the implementation of the method allows to eliminate the error caused by the non-identical phase angles of phase-shifting units in current and voltage channels. The structural diagram of the measurement means implementing the method is given. The paper shows the results of error analysis of the phase-shifting units which causes the difference between the input signal amplitude value and the signal amplitude at the output of the phase-shifting unit. The obtained results allow to choose the hardware and the measuring process parameters most appropriate in terms of accuracy and measurement time.

This paper analyzes the influence of impact parameters on the process of super-deep penetration of particles. The parametrical principle which reveals the possibility of super-deep penetration of particles is defined. The role of a shock wave of the detonation products as the factor of preliminary strain of crystalline lattice for the subsequent penetration of particles is shown. The algorithm of energy balance for super-deep penetration is developed. The mechanism of super-deep penetration by rupture of intermolecular and interatomic bonds during the penetration of the particles is offered. The substantiation of a dimensional interval of penetrating particles for super-deep penetration is made.

Method of finite element modeling is used to study the influence of hydraulic shot blasting on endurance limit of notched cylindrical specimens made of 12X18H10T steel by residual stress of the reference specimen. The results obtained are used as a basis for development of the method for estimation of endurance limit increment of parts strengthened by surface plastic deformation in conditions of stress concentration using the average integral residual stress criterion.

This paper deals with the ways to improve the efficiency of control of non-stationary operation modes of two-section methodical action induction heater. The problem of control of transient modes of multi-section induction heater is defined as searching for object control parameters which, during the transition to stationary mode in conditions of technological and power limitations, would provide effective (to some extent) transition to the stationary heating mode with required final temperature distribution of a workpiece leaving the heater. This problem is solved on the basis of non-linear mathematical model of the process considering technological and power limitations and parameters of power source. During the transition to the stationary mode, the heater is controlled through three channels: voltage applied to each section of the heater and voltage applied to the worpiece transfer mechanism. Different types of starting mode control algorithms considering the non-linear nature of ferromagnetic loading are analyzed, recommendations for choosing the power-efficient algorithms are given.

The paper describes the procedure of finding expressions for temperature fields of the flow through induction heater as an object with distributed parameters. The paper considers a formulation of two-dimensional problem in polar coordinates with further transition into Cartesian coordinates. To solve the partial differential system, the method of finite integral transformation, Laplace transformation and numerical-analytical method with using spatial spline interpolation of distribution signal are applied. A new method of realization of dynamic model of the object with distributed parameters in simulation software was proposed. The paper performs the simulation which gives basic statistic and dynamic characteristics of behavior of the heater temperature fields.

Urban heating networks powered by heating and power plant and boilers are complex brachigerous hydraulic systems. The main problems of their operation are insufficient pressure difference between direct and reverse pipelines, increased pressure in reverse pipeline, the deregulation of network (the discrepancy between the estimated and actual costs for heat consumers) and others. These problems can be caused by: excessive consumption of heat carrier, insufficient pipeline diameters, reduction of pipelines diameters as the result of deposits on their inner surfaces, the valves overlap in network sections with high velocities of heat carrier flow, parasitic circulation, etc. The problem of define which of the abovementioned problems is critical is quite complex. Computer models that allow the complete simulation of hydraulic and temperature modes of heating networks are the most effective and precise way to determine the main causes of the abovementioned problems that occur in every heating network. These models consider the heating network as the unified hydraulic systems (taking into account any number of inner ring structures).

The paper deals with the issues of using recycled aluminum alloys as protectors. The paper gives the characteristics of alloys, selection criteria for dimension-types and properties in case of using them the for oil reservoirs protection. The paper shows the protector designs, dimension-types and special features of using them in various operation conditions. Characteristics of protectors made of recycled aluminum alloys are represented. Testing is performed in order to determine the self-digestion velocity of protector alloys and relationships between protector potential and solution concentration are defined. Recommendations for defining the material design of protectors are given, as well as their dimension-types and application area depending on the oil-product storage conditions.

The paper analyzes the existing methods of shifting the oil well into steady production state. It shows that most control systems that have the bore-hole electric-centrifugal pump use the sensors of dynamic level of liquid. On the basis of the analysis of mathematical model of the oil well the method of its shifting into steady production state without the sensors by means of the open-loop control system is proposed. The analytical expressions are made up, allowing to calculate the parameters of the control input which provides achievement of the required value of dynamic level of liquid in the oil well according to its known parameters.

The simulation of a development process of such composite systems as corporate relationship is allied to the necessarily description of those components which form the conceptual model as well as their further affiliating. The creation of a mathematical model which is suitable for simulation of any composite system always precedes its conceptual model development. The objects are considered as elements forming a conceptual model of composite systems in this article. The definitions of these components and principal relations between them are defined. The concepts «point state» and «system of objects» were reviewed. The goal is to determine those objects' features which strongly influence the conceptual models development of composite systems.

Local systems for stabilization of production equipment operation parameters and controlled initial cable parameters which are traditionally used to control the manufacturing processes of telecommunication cables and are implemented with the use of PID controller do not give the expected positive result. In order to improve the control efficiency, the paper proposes to use the methods and means of advanced process control systems based on the predication model to provide the required quality of the telecommunication cable.