Volume 7 Issue 4


Volume 7 Issue 4

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Andrianova E.G.,
Raev V.K.,
Filgus D.I

Determination of the shortest hamilton paths in an arbitrary graph of distributed databases

A method has been developed for finding the shortest Hamiltonian path in an arbitrary graph based on the rank approach, which provides high efficiency and a significant reduction in the error in solving the problem of organizing the process of managing multiple transactions and queries when they are implemented in network databases. In many cases, existing solutions do not provide the necessary results in terms of access time and accuracy of the found solution. Using the developed method allows minimizing the idle time of computing devices, reducing the volume and time of data transfer from one device to another, increases overall scalability, minimizes data access time, etc. An important advantage of the proposed method is to reduce the number of elementary operations and the number of vectors being processed the queue of the operations of the request, which leads to a significant reduction in time to implement the procedures for the formation of echer di operations in the requests. Methods of graph theory were used in this paper. The effectiveness of the task solution was evaluated using a systems approach, system analysis and the theory of operations research. Processing of experimental data obtained during the work was carried out in accordance with the provisions of mathematical statistics.

Keywords: graph, Hamiltonian path, query, rank approach, short tree of paths, transaction, rank, distributed database.


Dubov S.S.,
Linkov V.V.,
Karbainova M.A.

Child’s information security in digital space of the Russian Federation 26

Our time is the time of rapid technological development. The Internet is becoming available to everyone, and it is expanding its influence in various fields. In addition, the number of users who are using the Internet and who are active consumers of different content is increasing. But the rapid development of technology has created new security problems. New types of threats are emerging, attack techniques are improving. Criminals are now trying to find their «victim»not only in the real world, but also in the digital world. So, today special attention is given to the issue of ensuring the user’s information security and user’s security in the digital world. One of the most vulnerable age groups are children. That is why one of the most important issues is the issue of protecting a child in such an environment. This article is devoted to the problem of information security of children and adolescents in our country. The article describes the main problem of the child in such an environment. On one hand, the virtual activity of the child is the key to its successful education. But, on the other hand, there are risks and problems in the digital world, such as access to prohibited content, that can cause harm to the mental health of a child. This article describes vulnerabilities in the information environment of students and educational institutions, as well as ways to counter the described vulnerabilities.

Keywords: IT education, information security tools, social engineering, hacking, auditing, vulnerabilities, protection, countering violations.



Bityukov V.K.,
Mikhnevich N.G.,
Petrov V.A.

Negative output voltage ripples of bipolar LM27762 DC–DC converter near maximum input voltage 24

The paper presents the results of studies of the operation of the inverting DC–DC converter with charge pump and LDO, which are part of the combined bipolar secondary power supply LM27762, at the near to maximum input voltage of 5.5 V and an output voltage of –4.9 V. The ripple voltages were measured at various load currents from 10 to 250 mA at the positive pole of the flying capacitor, at the output of the charge pump system and at the output of the microcircuit. It was shown for the first time on the basis of the obtained information that at low load currents up to about 107 mA the charge pump system operates in the burst mode, and at currents greater than 109 mA – in the charge pump mode with a constant frequency. The results do not confirm the information in the documentation on the microcircuit that, at the maximum input voltage of 5.5 V, the charge pump can enter the PWM mode in hot conditions. When working in burst mode, the presence of LDO in the LM27762 chip reduces the ripples of the negative voltage at the output. However, they significantly exceed the values given in the documentation on the chip. During switching to the constant–frequency mode, the level of negative voltage ripples at the output of the microcircuit decreases sharply, but it increases with further increase of the load current and exceeds the values given in the documentation.

Keywords: integrated circuit, DC–DC converter, charge pump, inverter, flying capacitor, LDO, burst and constant frequency modes.


Gurov E.V.,
Uvaysov S.U.,
Uvaysova A.S.,
Uvaysova S.S.

Nominal and actual values of inductor and capacitor parameters at high frequencies

Coil inductance and capacitor capacitance depend on overall dimensions, structure, and ambient factors. They do not vary with frequency. Reactive component impedance is determined by inductance or capacitance respectively, if active resistance is not considered. This is true for the frequencies which are significantly lower than the self-resonant frequency of the component. Parasitic parameters contribution increases on approaching the self-resonant frequency. Therefore, the componentʼs actual inductance and actual capacitance on operating frequency are defined. They are provided by manufacturers and differ from the nominal values. The actual values provide more accurate impedance of components near the considered frequency. Significant deviation from the considered frequency can cause impedance mismatch even more than the nominal values can provide. Frequency response of the high-frequency circuits such as analog filters and impedance match networks are determined by components impedance, not the nominal values. Thus, calculated values must be close to the actual values. The purpose of this article is to justify actual values application instead of nominal values.

Keywords: inductor, inductance, capacitor, MLCC, capacitance, impedance, reactance.


Kaganov V.I.,
Fam Ky

Redistribution of signals power in multipath system radio of communication 26

Two types of satellite radio of communication systems are compared: single-beam and multibeam. The problem of summation and redistribution of radio signal powers of communication systems is discussed. The power redistribution of a group of microwave transistor amplifiers between different beams is analyzed. An adder circuit based on bridge quadrature devices is considered in two- and four-ray systems. For two such cases, the scattering matrix of the signal power adder was compiled. On the basis of these two cases it is possible to compose a scattering matrix for the number of summed powers of microwave signals with the number of rays equal to 8, 16 and 32.

Keywords: microwave generator, adder, multipath antenna.


Pevtsov E.Ph.,
Demenkova T.A.,
Shnyakin A.A.

Design for testability of integrated circuits and project protection difficulties 18

Design solutions of domestic VLSI were obtained as a result of the application of computeraided design tools of a foreign supplier (CAD Synopsys, Cadence Design Systems and Mentor Graphics), based on standard libraries of PDK elements (Project Design KIT) of factories and IC-modules also supplied mainly by foreign companies. As a rule, the developer does not have its own production facilities, using the services provided by foreign factories (fablesscompanies). Due to this fact, relevant are the studies aimed at the development of a complex of measures, excluding the possibility of unauthorized changes into IC, i.e. protection of projects against intentional hardware and technology violations made during the formation of the control information for handing it over to the production facility and/or in case of IC manufacture at the factory. This paper considers this task from the standpoint of the analysis of the methodology of design for testability (DFT), i.e., a complex of measures that provide obtaining solutions at the design stage. The solutions include the verification of the correct performance of the manufactured chip by means of external tests and/or self-testing procedures. It was proposed, inter alia: 1) to analyze the libraries of standard elements used in the project with full disclosure of their specifications; 2) to create nodes with the physical non-cloning function in the projects on the basis of the libraries of standard elements in models and analysis programs; 3) to analyze IP modules used in the project with the maximum disclosure of structure, methods and algorithms for providing test coverings; 4) to provide for the development in projects of special test kits and methods of their generation at the design stage of functions in order to detect malicious nodes and programs both within SoC cores and at the level of system buses; 5) to develop at the design stage and to apply during tests a technique of special hardware measurements of parameters of the manufactured circuits and analysis of their results, inter alia, according to measurements of delays in distribution of signals and/or buses current consumption.

Keywords: design for testability, instrument bugs/Trojans, IC project verification, test coverings, self-testing units, design for security.



Bilyk V.R.,
Grishunin K.A.

Complex refractive index of strontium titanate in the terahertz frequency range 20

The recent progress in terahertz time-domain spectroscopy enables the accurate and reliable measurements of dielectric properties in comparison with the traditional far-infrared spectroscopy using an incoherent light source. The broadband THz-TDS is a powerful tool to determine the real and imaginary parts of a complex dielectric constant by the transmission which allows to detect the parameters of the soft modes in ferroelectrics. In this work, the terahertz time-domain spectroscopy was used to investigate the dependence of the complex refractive index of a single-crystal quantum paraelectric strontium titanate in the terahertz frequency range from 0.3 to 2 THz. It was shown that the low-frequency terahertz response of the material is determined by the soft phonon mode TO1. The measured experimental dependences showed a good agreement with the theoretical curves obtained from the analysis of the Lorentz oscillator model for the complex dielectric constant of strontium titanate. The obtained results are necessary for understanding the principle of possibility to manipulate the order parameter in ferroelectric materials and can be used to create energy-efficient memory devices with a speed of recording information close to the theoretical limit.

Keywords: terahertz radiation, ferroelectricity, terahertz spectroscopy.


Saveliev D.V.,
Fetisov L.Yu.,
Chashin D.V.,
Shabin P.A.,
Vyunik D.A.,
Fedulov F.A.,
Кettl W.,
Shamonin М.

Method of measuring deformations of magnetoactive elastomers under the action of magnetic field 25

Magnetic deformation is a change in the size and shape of a sample under the action of a uniform external magnetic field. The study of this effect in various materials provides deep understanding of the nature of magnetic and mechanical interactions. Moreover, magnetic deformation is of great interest from an engineering point of view for designing new devices. In magnetoactive elastomers containing magnetic microparticles in the polymer matrix, a giant deformation is detected under the action of an external magnetic field. The generally accepted methods for measuring magnetic deformation in magnetoactive soft materials are now practically absent. The article describes the installation for the study of the magnetomechanical characteristics of magnetoactive elastomers and demonstrates its experimental capabilities. The installation allows to measure deformations in the range from 0 to 12.5 mm with a resolution of 1 micron. The deformation curves obtained using these installations are required for developing actuators and sensors based on magnetoactive elastomers, and also for improving their manufacturing technologies.

Keywords: magnetoactive elastomers, magnetostriction, magnetodeformation, ferromagnetics, microparticles.


Yashin M.M.,
Mirzokulov Kh.B.

Symmetrized maxwell-garnett approximation as an effective method for studying nanocomposites 16

The symmetrized Maxwell-Garnett (SMG) approximation is considered as the most optimal method of an effective medium for the description of nanocomposite structures. This approximation takes into account the microstructure of the sample, which makes it possible to calculate the metal-dielectric system. Thus, SMG describes with good accuracy the structure of the nanocomposite. Besides, this approximation is applicable for granular alloys consisting of metal components. As a result, this technique can be considered as a universal approximation to describe a wide class of nanostructured materials. At the same time, this article discusses various methods of effective environment. In these methods, the metal component of nanocomposites and the dielectric matrix are replaced by an effective medium with effective permittivity εeff. It is necessary that the particles (granules) in such structures be small in comparison with the wavelength of electromagnetic radiation incident on the sample. Based on this, the spectral dependences of the transverse Kerr effect (TKE) in magnetic nanocomposites were calculated with (CoFeZr)(Al2O3) structure as an example at different concentrations of the magnetic component. The simulation was carried out at small and large concentrations (below and above the percolation threshold). The spectral dependences were obtained taking into account the form factor of nanoparticles and the quasi-classical size effect. Besides, the authors note and discuss in this paper the contribution of various mechanisms that affect the type of spectra of the transverse Kerr effect. Using the symmetrized Maxwell-Garnett approximation, the effective values of the granule size of the nanocomposites under study were found, and the tensor of effective dielectric permittivity (TEDP) was calculated. The obtained TEDP values allowed to simulate the spectral dependences of the magneto-optical transverse Kerr effect. The authors discuss and draw conclusions about the features of the obtained spectral dependences in both the visible and infrared regions of the spectrum. In addition, the practical and fundamental importance of the obtained results is noted. The importance of effective medium methods for the study of optical, transport and magneto-optical properties of magnetic nanocomposites is shown.

Keywords: magnetic nanocomposites, transverse Kerr effect, spectral dependence, symmetric Maxwell-Garnett approximation, effective medium, size effect.