METHOD OF COUNTERING DESTRUCTIVE ELECTROMAGNETIC INFLUENCES, BASED ON ADDITIONAL MODULATION WITH APPLICATION OF WAVELET TRANSFORMATION IN SPECIAL APPLICATION NETWORKS
I.V. Gilev, S.V. Kanavin, A.V. Popov, N.S. Khokhlov
The article discusses a method of counteracting destructive electromagnetic effects, based on the transfer of the signal spectrum using wavelet transforms in special communication networks (SS SN), operating on the basis of the WIMAX standard for mobile broadband access. A Gaussian bipolar pulse is selected as a model of destructive electromagnetic influence that affects the operation of a special purpose communication network. When this type of interference is affected by a WIMAX system signal, the normal operation of the CC SN is disrupted. The MHAT wavelet was chosen as the modulating function, since it is described in the time-frequency half-plane and its parameters depend on certain coefficients of the scaling factor and the time shift. Thus, it is possible to change the parameters of the modulated signal by changing the coefficients of the wavelet function by which it is modulated. MHAT wavelet, obtained as a result of double differentiation of the Gauss function. This method finds its application primarily due to the fact that the wavelet operates in the time-frequency half-plane and its parameters depend on certain coefficients (scaling factor and time shift). Thus, it is possible to change the parameters of the modulated signal by changing the coefficients of the wavelet function by which it is modulated. The results of this method are the transfer of the spectrum of the WIMAX signal to another frequency band, where the SS SN also functions by modulating the wavelet function, as well as increasing its power and expanding the spectrum.
Keywords:broadband communication system, WIMAX communication systems, modeling of functioning under conditions of destructive electromagnetic influences, а method of counteracting destructive electromagnetic influences using wavelet transform, MHAT-wavelet.
CHOOSING THE BEST ROUTING PROTOCOL FOR WIRELESS SENSOR NETWORKS
Due to the rapid development of wireless technologies, the optimal choice of network types and routing protocols is an urgent task. The current state of traffic models in terms of routing protocols in wireless sensor networks (WSN) is considered. The class of corresponding low-power network (LLN) provides efficient routing when transmitting data packets in small local networks. The AODV (Ad Hoc On-Demand Distance Vector) dynamic routing protocol in the BSS minimizes the length of the traffic route. Modeling traffic in the FSU is considered using color images as an example. For aggregated heterogeneous traffic flows in the network, the Kolmogorov criterion is applied, and dependences are obtained that allow one to calculate the Hurst coefficient using analysis of the variant variable . The same parameter is calculated as optimal for a packet of images on a sensor field of depending on the number of transmitting nodes and is equal to . For the WSN, various connection options with various connection options for the client and operator in the presence or absence of a base station are considered. Also, for wireless sensor networks, the RPL and AODV protocols are compared by simulation. Shown, the first is optimal. From the perspective of the 5th generation networks, it is possible to use D2D (device-to-device) connections. In this version of the two protocols (AODV, DSDV), AODV is more preferable both for the minimum total delay time and the minimum number of steps in data transfer. The development of 5th generation wireless networks will bring traffic to the level of broadband wired Internet and provide a qualitatively new level of opportunities for customers of these networks.
Keywords:wireless sensor network, RPL protocol, AODV protocol, D2D connections, Hurst coefficient, Kolmogorov criterion, 5G network.
DEVELOPMENT OF AN INFORMATION MODEL FOR SYNTHESIS OF COLOR COMPONENTS OF METAL-PLASTIC DENTURES
Modern medical practice is characterized by the universal use of technical means of diagnosis and treatment of diseases. One of the most rapidly developing trends in medicine is dentistry, in particular the aesthetic dentistry. The key problem in the aesthetic dentistry is the selection of an adequate color of dentures. To solve this problem, an information model was developed for synthesis of color components of metal-plastic dentures. A graph was developed to select the components that make up the mass of dyes for the selection of a given spectral component of the front part of prosthetic tooth. Regression analysis was used as the main method of analyzing the process of powder synthesis, which is a data analysis tool that allows investigate the influence of one or more independent variables on a dependent variable. Thus, a regression type mathematical model was developed in which the change of color components takes place in correlation; making it possible to compile interpolation equations and, based on them, to analyze and consider a single system for all sublevels of color gradations. To verify the operation of the developed information model, an algorithm and specialized software were developed. The conducted clinical studies have shown the full adequacy of the developed model.
Keywords:modeling, computer science, graph, regression model, algorithm, dentistry, denture, aesthetics.
AN ENGINEERING MODEL FOR CALCULATING SIGNAL LEVELS FOR TRANS-HORIZON TROPOSPHERIC PROPAGATION OF VHF AND MICROWAVE RANGES TAKING INTO ACCOUNT THE ELEVATION HEIGHTS OF THE EMITTING AND RECEIVING ANTENNAS
A.L. Khanis, S.V. Bespalko, V.A. Khanis, A.A. Khanis
The relevance of the article is due to the practical needs of calculating signal levels for over-horizon tropospheric propagation of radio waves in the absence of detailed data on the state of the troposphere and the earth’s surface. Currently, there are a number of numerical computer models for calculating signal levels in conditions of over-the-horizon propagation of radio waves, taking into account the elevation of the transmitting and receiving antennas, but they require a large amount of initial information in the form of detailed meteorological observations, forecasts of the state of the atmosphere, as well as data on the terrain and the state of the Earth’s surface, which are usually unavailable. The existing approximate engineering models that do not require detailed data about the conditions of radio wave propagation are developed in relation to the location of the transmitting and receiving antennas on the Earth’s surface. The model proposed in this paper is based on the introduction of an average attenuation multiplier for standard conditions in the troposphere, transmitting and receiving antennas placed on flight-lifting vehicles and splitting the propagation route into sections of line of sight and over-horizon propagation. The purpose of the study is to develop and describe a model for calculating signal levels (attenuation multiplier) in the conditions of over-horizon tropospheric propagation of radio waves, in relation to the case of placement of radiating and receiving antennas on flight-lifting vehicles. The tasks that are solved to achieve this goal consist in analyzing the radio wave propagation path and estimating the attenuation factor on the route as a sum of factors that characterize losses on sections of the route of various types – line of sight, diffraction zone and far tropospheric propagation. The method for estimating the attenuation factor on the track is to use a well-known engineering method for standard conditions of long-range tropospheric propagation as the base model for calculating the coefficient. The result of this work is a mathematical expression for engineering calculation of signal levels for over-horizon tropospheric propagation of radio waves, taking into account the elevation of the radiating and receiving antennas. The proposed model is based on the introduction of an average attenuation multiplier for standard conditions in the troposphere, transmitting and receiving antennas placed on flight-lifting facilities and splitting the propagation route into sections of line of sight and over-horizon propagation.it can be used for approximate estimation of the received signal levels during over-horizon tropospheric propagation of radio waves without detailed data on the state of the troposphere and the Earth’s surface.
Keywords:radio wave attenuation factor, horizontal tropospheric propagation of radio waves, calculation of signal levels on the propagation paths of radio waves, transmitting antenna, receiving antenna, flight-lifting equipment, refraction, diffraction, line of sight
PIECEWISE NEURAL MODEL BASED ON SPLIT SIGNALS FOR BERNOULLI MEMRISTORS
UDC 519.65; 621.3.01
E.B. Solovyeva, H.A. Harchuk
Actuality of the investigation theme is specified by complexity of mathematical modeling of nonlinear dynamic devices, since the analytical solutions of the nonlinear differential equation systems of high size are not always obtained, and numerical solutions are often accompanied by the problem of poor conditionality. In this situation, behavioral modeling is effective, herewith the object of investigation is represented as a “black or gray box”, and its mathematical model is constructed using the sets of the input and output signals. Behavioral modeling is important in conditions of restricted information of new elements and technologies, as well as under the complexity and variety of models built at the component level. The behavioral modeling of memristive devices actively developed using nanotechnology for energy-saving equipment is represented. A method of behavioral modeling of the transfer characteristics of memristive devices by means of piecewise neural models based on split signals is proposed. To reduce the dimension on approximating nonlinear operators and, therefore, to simplify mathematical models, are applied the following: neural networks, the signal splitting method that enables to adapt the model to the type of the input signals, and a piecewise approximation method for operators of nonlinear dynamic systems. On the basis of the proposed method, a piecewise neural model is constructed. This model includes five three-layer neural networks of simple structure (3x2x1, 100 parameters) and provides a significantly higher accuracy of modeling the transfer characteristic of memristors, the current dynamics of which are described by the Bernoulli differential equation, in comparison with the two-layer piecewise neural and piecewise polynomial models. The described results are of practical value for the behavioral modeling of memristors and various memristive devices, as well as of other nonlinear dynamic systems, since they develop a universal approach for approximating nonlinear operators based on neural networks.
Keywords:nonlinear dynamic system, mathematical modeling, nonlinear operator, nonlinear model, approximation, neural network, memristor.
DC MOTOR CONTROLLER WITH NEURO-ADAPTIVE FUZZY CONTROL LOGIC
Han Myo Htun, A.N. Yakunin
The development of motor drive controllers is an urgent task in industrial and robotic manipulators. DC motor controllers (DCT) can be used in various tasks, as their use provides flexible opportunities for the development of control algorithms. Many well-known controllers that use feedback cannot maintain system performance at an acceptable level. The paper proposes the development of a new DCT controller, which allows to increase the efficiency of its control by reducing tn (rise time), σ (overshoot) and tp (regulation time) when compared with other known controllers (proportional-integral-differential (PID) controller and fuzzy controller (NL) logic). The article discusses the development of a controller based on an adaptive system with neuro-fuzzy logic (ASNL) to effectively control the speed of the DCT with the load. The mathematical model of the developed controller in the environment of Matlab-Simulink is implemented. Comparison of the proposed controller with other known controllers is performed according to the following criteria: tn, tp and σ. To confirm the effectiveness of the proposed ASNL controller, it was compared with known controllers. The simulation results showed that the developed ASNL controller reduces tn compared to the PID controller by 6% and compared to the NL controller by 17%, tp compared to the PID controller by 37% and compared to the NL controller by 17 %, and σ compared to the PID controller by 6% with the load.
Keywords:DC motors (DC motors), proportional-integral-differential (PID), fuzzy logic (NL), adaptive neuro-fuzzy output system (ASNL).
COMPUTER MODELING OF MULTI-MOTOR ELECTRIC DRIVE SYSTEM IN MATLAB SOFTWARE
UDC 519.6, 621.3
S.A. Zagolilo, A.S. Semenov, M.N. Semenova, I.A. Yakushev
A multi-motor electric drive system of a mining combine is considered. Computer simulation was performed in the MatLab software package using the Simulink block library and the SimPowerSystems application. For research, a mining combine AM-75 was selected. The description of the power circuit of the main electrical equipment of the combine is given, which includes the engines of the swept working body, the rotary scraper conveyor, and the pick-up with two pick-up legs. To carry out the simulation, the Mathcad program calculated additional parameters of induction motors, which include the active resistances and inductances of the stator and rotor windings, mutual induction, reduced power, rated current, design and winding coefficients of the motors. A computer model of direct start of all asynchronous motors with a process relationship has been developed. The simulation results are obtained in the form of graphs of the time dependences of the main engine parameters: angular rotation frequency and electromagnetic moment. Plots of voltage and current of the supply network were obtained, as well as a graph of active power consumption. A qualitative assessment of the obtained results was made by determining the relative error of the simulated parameters and calculated data. During the assessment and analysis of the simulation results, minor errors in the engine parameters were revealed, which indicates the exact implementation of the computer model and the possibility of its use for engineering calculations.
Keywords:computer simulation, MatLab, Simulink, asynchronous motor, multi-motor electric drive, mining combine, angular rotation speed, electromagnetic moment, error.
MODELING OF THE ULTRAFILTRATION PROCESS ON ROLL MEMBRANES IN A CENTRIFUGAL FIELD
A.B. Golovanchikov, M.C. Doan , N.A. Merentsov
The process of ultrafiltration on roll-type membranes installed in the rotor of a filter centrifuge of a special design that provides atmospheric pressure in the zone of filtrate formation behind the membrane and centrifugal pressure in the zone of retant filtration to the membrane is considered. Equations are obtained for calculating the performance of filtrate and permeate and the concentration of solute molecules in them. An example of calculation is given in comparison with the installation of a single layer of sheet membrane on the side wall of a perforated rotor. The results of numerical calculations of the main parameters of the process of ultrafiltration of an aqueous acylase solution using the developed algorithm at the rotor rotation speed ω = 100 rad/s, the rotor radius Rn = 0,25 m and the membrane width b = 0,5 m show that the area of the roll membrane increases 12 times, and the degree of concentration of the solution almost 6 times, while the permeate consumption increases almost 10 times compared to the sheet membrane laid in a single layer on the wall of the perforated rotor. However, the cleaning of permeate in a rotor with a roll membrane is reduced by almost 12.5 times, since the average concentration in permeate increases from 1·10-5 % to 2,6·10-5 %.
Keywords: ultrafiltration, roll-type membrane, centrifugal field, performance, retant, permeate, concentration.
ESTIMATION OF PAIR LINEAR REGRESSION MODELS WITH PARAMETERS IN THE FORM OF LINEAR OPERATOR MATRICES OF TWO-DIMENSIONAL VECTOR SPACE
M.P. Bazilevskiy, L.N. Vlasenko
The key problem in constructing a regression model is the choice of its structural specification, i.e. the composition of the variables and the mathematical form of the relationship between them. All currently known regression specifications are based on the fact that their unknown parameters are matrices of linear operators of a one-dimensional vector space. In this paper, for the first time, linear regression models with parameters in the form of matrices of linear operators of a two-dimensional vector space are considered. It is shown that such models can be used to predict the values of the explained variable, and for this, the researcher does not need to set the predicted values of the explanatory variable, since they are sequentially determined by the model. To estimate the proposed models, an optimization problem is formulated based on the least-squares method with restrictions. Using the method of Lagrange multipliers, it is proved that solving the formulated problem reduces to solving linear algebraic equations system. An example of estimating the proposed models for specific data is considered. As a result, the error sum of squares by the developed model turned out to be five times less than the error sum of squares by the classical pair linear regression model.
Keywords: regression model, linear operator, vector space, forecasting, ordinary least squares, method of Lagrange multipliers.
ANALYSIS OF MATHEMATICAL MODEL OF RELIABILITY OF THE RESPONSIBLE NODE OF THE RADIO ENGINEERING DEVICE IN THE PRESENCE OF RESERVE BLOCKS IN CASE OF DANGER OF SHORT CIRCUIT
J.V. Korypaeva, N.A. Aleynikova, N.E. Krasova
The problem of duplicating the responsible node of a radio engineering device with several backup units in the event of a short circuit or other potential danger of sudden disconnection of the device is considered. To study such situations, when modeling a possible sudden failure of the unit, a small positive parameter is introduced in the denominators of the failure rates of the main device and backup units. In this regard, the system of Kolmogorov equations for the considered case will be singularly perturbed. For the received model key features device reliability: the probability of loss of function of the expected time of failure of the last overlapping block variance and the risk of failure of the unit. Similar characteristics are found for the corresponding problem without reservation. On the basis of a comparative analysis of the results obtained for the reliability characteristics of the main task and their comparison with the results for the system without redundancy, a number of features are identified and conclusions are made about the feasibility of redundancy in this case. For specific values of the number of duplicate blocks, failure rates and small parameter, a table of results for the mathematical expectation of the time of failure of the last device is given and conclusions are made.
Keywords: reliability prediction, redundancy, Markov chains with a finite number of States, singular perturbations.