The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The main reason for the asymmetrical modes are different terms of the phases of the electrical network. These modes arise from the asymmetry of power sources; due to unbalance operation of the electric grid elements (longitudinal asymmetry); due to significant unbalanced loads on phases (transverse asymmetry). To ensure compatibility of electrical networks and general purpose networks, consumers need...
Most modern wireless transceiver complexes require the use of linear power amplifiers having a high efficiency of power supply use. The amplitude characteristic distortion increases the level of intermodulation products, reducing the receiving range and polluting the signal spectrum. The use of the cartesian loop reduces the power amplifier non-linearity without causing a significant increase of the...
The methodology of structure selection of hybrid correction device for centralized and distributed electrical networks is presented in the article according to the results of mathematical modeling and computer simulation. The reasonability of hybrid correction systems usage in distributed and centralized networks are proved. The mathematical model of centralized and distributed network with hybrid...
The paper considers the problem of improving the reliability of the hardware and software of autonomous unmanned underwater vehicles. The aim of the work is to investigate and develop methods for emergency homing of the AUV to the source of the reference signal using minimal input data. The idea is proposed of estimating the speed of the source and receiver approach by analyzing the deviation of the...
The approaches for the parametric synthesis of the automatic control system (ACS) using the genetic algorithm that performs an approximation of Pareto-optimal solutions set are suggested. As a result, two approaches to multi-criteria optimization of ACS were considered: (1) the optimization problem was considered to be three-criteria for equally important criteria, (2) the optimization problem was...
The main task of modern electric networks is the reliability of electricity supply to consumers, as well as in optimizing voltage levels. One of the possible measures to increase reliability is the construction of a rational topology of the electrical network and the use of distributed generation in the form of alternative sources of electricity. Such networks allow you to dynamically adjust the parameters...
Based on the quasi-static approximation and taking into account the linearized equations for a prestressed electro-magneto-elastic medium, the problem of oscillations of a layered half-space with initial mechanical strains is considered. The Green function of an electro-magneto-elastic medium is constructed. The effect of the initial deformations in different medium parts on the phase velocities is...
The method of adaptive compensation of echoes in the range of significant delay values of telecommunication systems of loudspeaker communication is investigated. It is shown that it is possible to ensure a high rate of convergence and a high degree of echo cancellation in the formation of adaptive filtering in a localized neighborhood of delays.
A mathematical model to study changes in the energy parameters of a submersible electrical motor (SEM) through rotor pack parameters variations has been completed. Resistance variations influence coefficients of rotor pack short-circuited winding PEDN (SEMI)32–117 to power losses in the pack as well as efficiency and SEM air gap torque were determined in the Mathematica software. The worst-case energy...
The non-iterative algorithm that reveals the general physical basis of measuring processes and instrumental (computer) computations is proposed and investigated. The algorithm is based on the previously proposed postulate and consists in finding the optimal, locally defined width of the averaging interval. The optimal width of the interval provides the smallest error when measuring or computing the...
The aim of the paper is to calculate the maximum magnetic induction value of the transformer's core which provides a specified value of current distortion. To solve this problem, an experimental study was made on the dependence of the magnetic induction on Total Harmonic Distortion for current. The processing of the measurement results was carried out using Fourier series, harmonic analysis and interpolation...
The technique has been developed for studying the noise immunity of electronic systems of unmanned aerial vehicle on the basis of physical modeling. The mathematical models, the scheme of experimental stand and examples of parameters calculation for physical simulation of electromagnetic interference in communication line under the influence of magnetic fields of indirect lightning strike. The example...
Importance of the genetic algorithms (GA) usage in the investigation of an ultrashort pulse peak voltage in a printed circuit board (PCB) bus of autonomous navigation system (ANS) is highlighted. Trapezoidal ultrashort pulse propagation along the conductors of the PCB bus was simulated. Using GA an optimization of the 10 parameters for loads at the ends of the bus conductors was made. The optimization...
In this paper, a new control method for walking in-pipe robots is discussed. The method is based on a combination of a linear quadratic regulator for systems with explicit mechanical constraints and a proportional-derivative controller formulated in terms of end effector coordinates (Cartesian coordinates of the robot's foot that takes the step). The performance of the proposed method is measured...
The article deals with the method for the assessment of the fiber-optic communication line reliability taking into account the effect of the optical fiber tension, the temperature influence and the built-in diagnostic equipment errors of the first kind. The reliability is assessed using the theory of Markov chains and probabilistic mathematical modeling. The reliability is assessed in terms of the...
In the paper, operation algorithms of the N-OFDM modem for channels with the Additive White Gaussian Noise (AWGN) are considered. The algorithms are based on the Hartley transform under the optimal demodulation by the estimation of the received signals amplitudes using the Cauchy method. The experimental results for interference immunity estimation are provided for different values of spacing frequencies...
Article is devoted to the system development allowing to restore the volume of the left ventricle of heart, to estimate final systolic and diastolic volumes on the basis of the sequence of MRT-images from a parasternal position of a short axis in the automatic mode. The realized system was built on convolutional neural networks, 500 patients were used for training, for testing 200.
Defining the possibility of resonant modes onset in power supply systems (PSS) is a relevant task in selection and validation of VAR compensators (VC). At the current resonance negative consequences take place: supplemental heating of conducting parts, overload with the consequent outage of static capacitor batteries (SCB), excessive heat of transformer windings and a core. Existing practices to determine...
The method of realization log-periodic vibrator antennas in asymmetrical execution is shown in the work. The method is based on a two-wire collecting line of four conductors with alternating polarity. The proposed construction of a log-periodic antenna made it possible to form a plane of symmetry and a connection of vibrators on each of the conductors of the same polarity. Thus formed the structure...
This paper describes the possibility of developing the gradient meter of magnetic field strength. N-germanium oscillistor is used as the magnetically sensitive converter. The experimental and theoretical studies results of the threshold value of magnetic field strength and dependence the oscillistor oscillation frequency on magnetic field strength are described in the paper. The scheme of the magnetically...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.