Vol 29, No 2 (2019)

Introduction. The time interval systems for controlling train movement operated under the influence of significant industrial disturbances, interference from the electric current of traction rolling stocks, and significant climate changes that result in fluctuations of parameters of circuit elements. 
Materials and Methods. To solve the problem, various methodologies of compensation for disturbances are considered in the paper; the method of coordinate compensation for disturbances at the input of a quadripole of rail lines is adopted as the main one. The equation of the transfer function of the correcting link is determined, assuming an indirect measurement of the input resistance of the rail line, which is a function of the conductivity of the insulation.
Results. The article presents the results of the research of the invariant capabilities of the disturbance compensation principle. It is shown that disturbances compensation with a corrective link included at the input of a quadripole allows one to significantly reduce the dynamic range of the output informative signal change in each of the classes, i.e. classes have become more compact, and the quality of classification has become 5 times higher than in the absence of compensation of disturbances.
Discussion and Conclusion. The results confirm the effectiveness of the proposed method for the coordinate compensation of disturbances in rail lines with an open circuit in the absence of the possibility for organizing feedback, a variable circuit in each of the classes of states, and the impossibility of creating a physical additional channel for the transmission of the disturbance. Using the proposed method in the construction of modern classifiers will significantly improve the stability of the functioning of train control systems; eliminate errors of the first kind, leading to unproductive idle train, and errors of the second kind, leading to accidents and crashes.

Introduction. The solution of the simulation problems critical to rounding errors, including the problems of computational mathematics, mathematical physics, optimal control, biochemistry, quantum mechanics, mathematical programming and cryptography, requires the accuracy from 100 to 1 000 decimal digits and more. The main lack of high-precision software libraries is a significant decrease of the speed-in-action, unacceptable for practical problems, in particular, when performing multiplication. A way to increase computation performance over very long numbers is using the residue number system. In this work, we discuss a new fast multiplication method with scaling the result using original hybrid residue positional interval logarithmic floating-point number representation.
Materials and Methods. The new way of the organizing numerical information is a residue positional interval logarithmic number representation in which the mantissa is presented in the residue number system, and information on an absolute value (the characteristic) in the interval logarithmic number system that makes it possible to accelerate performance of comparison and scaling is developed to increase the speed of calculations; to compare modular numbers, the provisions of interval analysis are used; to scale modular numbers, the properties of the logarithmic number system and approximate interval calculations using the Chinese reminder theorem are used.
Results. A new fast multiplication method of floating-point residue-represented numbers is developed and patented; the authors evaluated the developed method speed-in action, compared the developed method with classical and pipelined multiplication methods of long numbers.
Discussion and Conclusion. The developed method is 2.4–4.0 times faster than the pipelined multiplication method, and is 6.4–12.9 times faster than classical multiplication methods.

Introduction. At present, the problem of increasing performance properties of machine parts, tools and tooling by improving the physical, chemical and mechanical characteristics of their executive working surfaces is relevant. One of the modern methods of obtaining coatings on the surfaces of parts is the method of electrospark alloying. 

Materials and Methods. To form doped layers in a drop-shaped electro- ass transfer, we used iron in the form of a parallelepiped as a being processed material (cathode) and tungsten was used as a processing material (anode). A nonlinear initial boundary value problem and a computational scheme are suggested for determining the temperature at all points (temperature field) of the cathode made in the form of a parallelepiped with the location of several heat-emitting drops on its face.

Results. The paper presents an algorithm for solving the problem by the second Green’s formula of finding the temperature field in the cathode made in the form of a parallelepiped, in this case the described nonlinear model of the flow from droplets to the parallelepiped is replaced by a linear model. An algorithm is constructed and calculations are carried out to determine the temperature values at all points and the temperature flow in the cathode in the case of one average drop on its face. 
Discussion and Conclusion. To achieve higher coating properties and a greater efficiency of the electrospark alloying, it is necessary to calculate the temperature field and heat flow of the cathode points under studying. The proposed mathematical model is calculated for the case of one drop placed on the boundary of a heat-conducting half-space. When choosing an anode material depending on the erosion resistance to obtain the required thickness of the surface layers with the specified functional properties, the developed calculation method is used.

Introduction. When harvesting grain crops, various trash and harmful impurities come to the combine bunker together with grains. Various modern grain cleaning machines do not provide for complete separation of ergot sclerotia from grains, because of the closeness of their linear dimensions (width, thickness and length) and speed of soaring. Cleaning seeds from ergot sclerotia having the density less than density of grain, is possible in an aqueous solution of salt. 
Materials and Methods. The immersion of separately taken rye grains in water (ρzh = 1,0 ∙ 103 kg/m3) and aqueous solutions of sodium chloride (NaCl) with density ρzh = 1,09 ∙ 103 kg/m3 and ρzh = 1,15 ∙ 103 kg/m3. The ellipsoid is taken as the geometric model of the grains. Theoretical studies were performed for the grain density ρz from 1.2 ∙103 kg/m3 to 1.5 ∙ 103 kg/m3, lengths lz from 5.0 · 10–3 m to 10.0·10–3 m, widths b from 1.4 · 10–3 m to 3.6 · 10–3 m and thickness δ from 1.2 · 10–3 m to 3.5 · 10–3 m based on the methods of mathematical modelling using the laws of hydrodynamics.
Results. The speed ʋz and duration tп of grain immersion in liquids are main parameters taken into account when developing a machine for cleaning the grain material from ergot sclerotia with a wet method. To determine these parameters, it is necessary to take into account the geometric shapes of the grains, which have a large variety. 

Discussion and Conclusion. It is established that the calculated values of the speed of grain immersion in liquids of different density are comparable with the experimental values of the same order. They are close and differ by no more than 10 %. 

Introduction. Many studies show that the chopped feed quality depends on the plants chopping quality. The quality of plant chopping, provided by a forage harvester, is defined by particle length distribution. It is important to find the theoretical basis of grass chopping regimes for making haylage and other kinds of feeds. The purpose of this study is to develop an algorithm and techniques to assess the quality of plant chopping based on mathematical models of chopping with the flail and double chop forage harvesters.
Materials and Methods. Mathematical models of a flail type unit and double chop unit were presented and used to develop the algorithms and method of calculating the cut length distribution.
Results. The algorithms and computation methods of cut length distribution were presented for a flail type unit and a double chop unit. The effect of the plant height, the height of cut, feed and the average length of cut on the mass fraction of particles within the specified ranges of lengths were investigated.
Discussion and Conclusion. A flail forage harvester is not able to harvest the grass crops for making haylage with 45–75 % forage particles, the length of which is in the range from 8 mm to 19 mm. A double chop forage harvester allows harvesting the grass crops for making haylage only when auger angular velocity and/or flywheel or cylinder drum angular velocity is regulated. A double chop device can be used to chop plants for preparation of various forages if auger angular velocity and/or flywheel or cylinder drum’s angular velocity is regulated.

Introduction. The technological processes of the washing contaminations are largely determined by the nature of the surface being cleaned, the contamination type and the environment, in which the cleaning is carried out. The efficiency of the process depends on the contact of the detergent with the surface being washed. The wetting characteristic is a contact angle, which is a measure of the relative attraction of a liquid to a solid and to liquid itself. The physico-chemical activity of the washing medium determines the costs and, consequently.
Materials and Methods. The determination of the contact wetting angle is based on the statistical processing of a photograph of a detergent drop on a horizontal surface by a specially created program that allows obtaining an array of data to describe the shape of a drop from which the contact wetting angle is calculated. The values of the contact wetting angle were measured when varying concentrations of such synthetic detergents as Labomid-203, MS-8, ML-51, etc. Multiplicative power functions connecting the magnitude of the contact wetting angle with surfactant concentrations were obtained.
Results. The studies has shown that an increase in the concentration of potassium monoborate with Labomid-203 by 1 % leads to a decrease in the contact wetting angle by 0.54 %; potassium monoborate with MS-8 by 0.78 %; and potassium monoborate with ML-51 by 0.48 %, the function shows a decreasing return to an increase in concentration.

Discussion and Conclusion. In all the considered cases, a decreasing return of the magnitude of the contact wetting angle to an increase in the concentration of surfactants was established, regardless of which combination of substances was used. That is, the investigated concentrations of surfactants exceeded the limit value when they gave an increasing return to the increase in their content in the washing solution.