mathematical model

The article is devoted to the problem of designing frequency tracking devices in a complex signal and noise situation. The article presents a mathematical model of the device, which takes into account possible structural and parametric changes of the device, changes in the frequency of the input signal, its angular modulation and time-varying noise level in the input mixture. Developed and described software application for the analysis of this model allows you to quickly change the values of parameters and monitor the response of the device to changes in the input signal.

The article proposes a solution of the forward kinematics problem for a welding manipulator with six degrees of freedom. Solving this problem is the first necessary step in creating a control system for this manipulator. This will make it possible to determine the displacement, accelerations and moments in each of the manipulator parts and will ensure accurate positioning of the welding tool.

The arc overvoltages during the single phase to earth faults in electrical distribution grids of 6-35 kV are the object of the research in this paper. The development of 35 kV distribution electrical grids is accompanied by the construction of new overhead and cable power lines. It causes a change of the capacitive earth fault current in the grids and also affects the multiplicity of overvoltages in electrical distribution grids during the single phase to earth faults.

The article deals with constructing and implementing mathematical models of non-isothermal moisture transfer during drying of anisotropic capillary-porous materials, in particular wood, taking into account the movement of the evaporation zone for non-steady drying schedules, as well as to the development of effective analytical and numerical methods for their implementation.  An analytical-numerical method for the determination of non-isothermal moisture transfer under non-steady schedules of the drying process has been developed, taking into account the dynamics of the phase transition bou

An universal mathematical model of an induction machine (IM) has been constructed, taking into account the saturation of the main magnetic circuit of its magnetic core and the active power losses.  The proposed approach to IM modeling expands the abilities of MATLAB / Simulink environment for analysis of the electric power supply systems (microgrid in the smart grid) with the nonlinear elements and dynamic load in abnormal, asymmetric and fault regimes.

With an increase of equipment parameters, such as the pressure of the sealing medium and the speed of shaft rotation, the problems  ensuring its hermetization efficiency are rising up.  In addition to hermetization itself, the sealing system affect the overall operational safety of the equipment, especially vibratory.  Groove seals are considered as hydrostatodynamic supports capable of effectively damping rotor oscillations.  To determine the dynamic characteristics, models of grooved seals and single-disc rotors with grooved seals are examined.  The obtained analytical dependences for com

The dissolution process of potassium chloride particles in the apparatus with two-blade mechanical stirrer was investigated and the mass transfer coefficient was determined. The experimental results were generalized by criterion dependence. The independence of the mass transfer coefficient from the solid particles diameter was confirmed. A countercurrent process of potassium salt dissolution in two apparatuses with a mechanical stirring was considered. A mathematical model for countercurrent dissolution was developed and the efficiency of this process was determined.

The process of paraffin formation has been considered, including the peculiarities of the paraffin structure as a result of phase transitions with a decreasing temperature. Mathematical models for thermodynamic and kinetic calculations of the "solid-liquid" system phase equilibrium have been developed. To shift the "fuel oil-paraffin" balance towards the liquid, it is necessary to reduce the activity ratio of solid and liquid phases by introducing into the system a substance with a lower solubility parameter.