Subject of Research. The paper presents experimental study results of the gain factor effect of an erbium doped fiber amplifier on the noise floor level of a fiber-optic interferometric acoustic sensor. Fiber-optic sensor is based on a Michelson interferometer. The optical amplifier is located behind the compensating interferometer which induces the auxiliary phase modulation to the interference signal. The homodyne demodulation algorithm is used to recover the sensor phase signal. Method. During the experiment there were no external acoustical impacts on the sensor. The power control of optical signals from the fiber amplifier was performed. Noise signals from the sensor were written into data files under the different values of the fiber amplifier gain factor. Spectral estimations of the noise floor level of the fiber-optic interferometric sensor were performed by the averaged modified periodogram method under the different values of the fiber amplifier gain factor. Obtained results were used to define the dependence of the noise floor level of the fiber-optic interferometric sensor on the fiber amplifier gain factor. Main Results. Mean noise floor levels were equal to 64 urad/Hz0.5 at 355 Hz, 68 urad/Hz0.5 at 450 Hz and 66 urad/Hz0.5 at 500 Hz. Experimental results showed insignificant increase of the noise floor level of the fiber-optic interferometric sensor with the growth of the optical amplifier gain factor from 14.6 dB to 25.8 dB. The gain factor increase was about several percent and did not exceed inaccuracies of performed measurements. Practical Relevance. The absence of significant changes in the noise floor level of the considered fiber-optic sensor with the changing of the fiber amplifier gain factor is caused by the intensity noise suppression of the used demodulation scheme. The considered fiber amplifier might be used for the amplification of optical signals from the fiber-optic multiplexed array of fiber-optic sensors without the significant deterioration of their noise performance on condition that the homodyne demodulation algorithm with the intensity noise suppression is used.

Subject of Research. The paper presents  research results on object structure effect, that is the type and size of its elements, on optimal level of computer generated Fresnel holograms binarization in terms of reconstructed image quality. Method. The study was carried out through mathematical modeling of synthesis and reconstruction of holograms of various objects with 80x80 nm pixel size using different binarization  levels, and comparing the quality of reconstructed images. All numerical experiments were carried out in a software package for the synthesis and reconstruction of holograms using the following hologram synthesis and reconstruction parameters: wavelength equal to 13.5 nm, hologram pixel size equal to 20x20 nm, distance between object and hologram planes of 20.3 μm, reference beam angle of 18.1. A criterion for  the quality estimation of reconstructed image was a number of gradations in the threshold processing of this image, in which the intensity distribution in the reconstructed image would be identical to the intensity distribution in the original object. Main Results. The dependency graphs between binarization level and thenumber of permissible gradations for threshold image processing are obtained. For binary transparency objects used in the research, they are curves with two pronounced peaks, usually located at levels 0.2 and 0.34 along binarization axis.The object structure has an effect on specific value of optimal binarization level and on the maximum number of threshold processing gradations; the general nature of researched dependency remains unchanged even for complex transparency objects. Practical Relevance. The revealed dependency gives the possibility to accelerate the optimal level choice of synthesized holograms binarization.

Subject of Research. A method is proposed for the contrast enhancement of the Earth's surface images  obtained by airborne optoelectronic complexes of space remote sensing systems. The relevance of the proposed method is confirmed by the results of contrast estimation  for space images obtained by modern recording equipment and the results of the contrast calculation for modeled survey conditions. Method. The method is based on the idea of combining different exposure space images. This combination gives the possibility to get the resulting snapshot with an extended dynamic range of brightness. Such picture has a high contrast in the field of dark and light halftones and displays the details of the observed objects better. Main Results. The contrast of the image obtained when selecting the survey parameters by traditional method is estimated. It is concluded that the quality of the images obtained from space is currently limited, since the parameters of the onboard optoelectronic complex do not provide taking into account a larger number of objects with different optical characteristics that are within the capture area of the recording equipment. On the basis of research, an approach to images contrast enhancement is proposed, the essence of which is to expand the dynamic range of brightness and, as a result, to increase the contrast of the images obtained. Practical Relevance. The proposed method for the Earth's remote sensing data processing gives the possibility to obtain images of objects located on the Earth's surface in any light conditions suitable for interpretation. This fact will improve the accuracy of information provision when performing work survey support and mapping areas

The paper presents experimental studies and the way of chromaticity formation on stainless steel surface at the exposure of pulse laser radiation. Methods of reflection coefficient calculation of oxide iron films on iron are described. We perform calculation of reflection coefficient dependence on wavelength in the visible range and thickness of an oxidic film on the marked surface. The effect is shown that an oxidic film thickness has on the formed surface color owing to interference on the system of films of iron oxide and iron. It is shown how reflection function is displaced to the left and its amplitude ЭКСПЕРИМЕНТАЛЬНЫЕ ИССЛЕДОВАНИЯ ПО ФОРМИРОВАНИЮ ЦВЕТНОСТИ … Научно-технический вестник информационных технологий, механики и оптики, 2018, том 18, № 4 582 decreases with the hade increase. By results of raster electronic microscopy significant oxygen increase in the places of exposure is recorded that points to formation of oxidic films. The profile analysis of oxidic films obtained on the metals surface is carried out and the dependence of chromaticity of the modified surface on laser radiation parameters is shown. 

The paper presents the study of refraction index, iodine number and relative percentage of fat content of a series of industrial vegetable oils, their two- and three-component blends and oil extracts of dry crushed medicinal plant raw materials (St. John's wort, celandine and dandelion root) by refractometry method. Oil extracts of plant raw materials were obtained in a water bath at 90° C within an hour followed by exposure for five months at room temperature. Before measurement, extracts were cleared by centrifuge process. We showed the influence of nature, ratio and mixing order of components on the optical properties of the simulated two- and three-component oil compositions due to structural and chemical transformations of triglyceride associates of individual oils in blends. The marked selectivity of individual oils-extractors was represented, regardless of their belonging to a certain classification group, as well as the increase in the extractive capacity of blended compositions in respect of plant raw materials of different nature and its anatomical parts. It was shown that the selectivity of the extractants is influenced by the presence of parallel running contra-directional and also the selective adsorption processes of lipophilic components of the oils and their blends by plant raw materials in the studied heterogeneous systems.

Subject of Study.Dendrimers are hyperbranched polymeric molecules that regularly branch from a single center. Dendrimers are used in biomedical applications to deliver drugs and genetic material to cells. The present work considers the study of the formation of lysine dendrimer complexes with therapeutic tetrapeptides and the equilibrium properties of the complex. Two systems were studied consisting of one second-generation lysine dendrimer and 16 tetrapeptides. In the first case, the system consisted of a dendrimer and 16 free molecules of Epithalon peptide. In the second case, the system consisted of a dendrimer and 16 chemically bound to its ends  Epithalon peptide molecules. Method. The study was carried out by computer simulation by the molecular dynamics method. Main Results. The sizes and internal structure of the complex and conjugate of peptide molecules with dendrimer were compared. It is found that in the case of free Epithalon, peptide molecules are adsorbed not only on the surface but can also penetrate into the dendrimer to form a stable complex with it. In the case of a conjugate, the peptides penetrate less into the dendrimer, but, being mainly on the dendrimer surface, they compress the dendrimer inwards, forming a more compact structure than the structure of complex. Practical Relevance. Such complexes and conjugates can be used in the future to deliver various therapeutic peptides and other drug molecules to target organs

The paper proposes a novel approach to the construction of actuators for automation and robotics based on the use of new electroactive polymer materials – swelling hydrogels. The hydrogel pH-sensitive materials containing two polymer components, crosslinked polyacrylic acid and polyvinyl alcohol, are obtained. A procedure for the synthesis of hybrid hydrogel is described, and the achieved values of their characteristics, degrees of swelling in water and water solution of salt, are given. A method of hydrogel elements preparation with a specified geometric configuration was developed, and cylindrical and also ring-shaped samples were prepared. Mechanical properties of the prepared hydrogels at compression were measured. It is shown that the hybrid hydrogels exhibit higher strength and elasticity than the one-component polyacrylic acid hydrogels obtained by the same method. An actuator design is proposed with a hydrogel as a controlled element. An experimental layout of such actuator was constructed. The stability of material characteristics was determined, and methods for the electrodes fixation and electric current supply were developed. It was found that ring-shaped samples of hydrogels demonstrate electromechanical response – compression when electric current passes through their cross section. This fact was the evidence that these hydrogels can be used as a linearly operating generator of mechanical force. It is shown that this effect is more pronounced for samples swollen in water solution of sodium sulfate rather than in distilled water.

The paper presents a spectroscopic study of the complexation of ions of various metals on the surface of polyelectrolyte polymer hydrogels. The object of the study was a polyelectrolyte hydrogel based on a copolymer of acrylic acid and acrylamide, which sorbs the ions of various metals by means of chemisorption mechanism with the formation of chelate complex compounds on its surface. IR spectra are obtained for complex compounds of a polymeric hydrogel with metals in the sorption process at definite intervals of time. We study the sorption dynamics and the complexation mechanism of divalent and trivalent metals with polyelectrolyte hydrogel based on a copolymer of acrylic acid and acrylamide. It is found that the formation rate of complexes on the surface of the polymer hydrogel depends on the type of metal. It has been shown that such metals as cobalt, lead, cadmium, nickel, manganese and aluminum form mainly a carboxylate type of complexes, zinc forms an acrylamide type and copper, iron and chromium form complex compounds of mixed type. The performed researches can find application at synthesis of polymeric materials for selective sorption of certain kinds of metals. The obtained results indicate the principal possibility of hydrogel application based on acrylamide and acrylic acid copolymer as sensor materials for the detection of ions of various metals in aqueous solutions.

Subject of Research.We have carried out the research of existing synthesis methods of the video sequence intermediate frames based on the procedure of motion estimation and compensation. A method for the video sequence intermediate frames synthesis is proposed based on the techniques of images spatial interpolation and the procedure for true motion estimation and compensation of the video sequence. Method. The paper describes the approach for the synthesis of video sequence intermediate frames based on the true motion estimation principle. The approach is based on the iterative hierarchical refinement procedure for the elements of the vector field and the approach for spatial interpolation of particular regions of the frame based on the image area fill techniques. Main Results. Сomparison results of the proposed approach with existing modern analogs show its higher efficiency in synthesizing frames of video sequences containing objects with complex motion. Practical Relevance. The proposed approach can be used in practice in the task of video sequences encoding and increasing of their frame rate

This paper presents development experience of architecture, principles of functioning, software engineering and modeling of multi-agent system for information support of regional business processes. The main purpose of the system is integration of distributed heterogeneous information resources and web-services devoted to innovations in the Internet. The system provides an automated search of potential business partners, an interactive innovation chains construction and selection thae most efficient of them. The necessity of system dynamics modeling methodology using in development of business processes support systems is discussed. Agent-based technologies are examined. Special attention is given to development of virtual business environment conceptual model. Our conceptual model is used as a basis for the system structure, algorithms, functionality and relationships between its main architectural components representation. Specifically, we show how to use the conceptual modeling methodology, system dynamics and multi-agent system technology in developing a multi-agent system for integration of distributed heterogeneous information resources and services devoted to innovations.

Subject of Research.The paper presents the results of experimental assessment of relationship force between  database normalization degree and database response formation time on a query. The research aim lies in the search of objective assessment of correlation force between database normalization degree and the run time of the enclosed inquiries to it depending on the required depth of the recursion realized in the inquiry ("normalization paradox" model). Method. The applied method is based on implementation of the correlation analysis according to the results of a numerical experiment for "normalization paradox" identification. Main Results. It is established that correlation between the recursion depth caused by achievement of a certain normal form of tables and inquiry performance time is rather weak in databases on the ORACLE platform. Interrelation between the database volume determined by the number of considered objects and delivery formation time is also weak. The valid conclusion is formulated about the absence of grounds for carrying out the database denormalization or not achievement of high normal forms for the good of the increase in its speed when performing requests for selection of records. All significant conclusions are drawn on the relation of factual databases on the ORACLE platform. Transposition of results on the other up-to-date database systems  was not performed. Practical Relevance. The practical relevance of work consists in objective justification of the need (but not sufficiency) for reductions of the relations of the relational database under control of ORACLE Database 11g R2 to the highest normal forms for ensuring its integrity. The research result novelty is caused by experimental confirmation of the hypothesis validity about selection time dependence of tuples on database normalization degree at the recursive selection procedure and formulation of "normalization paradox" model for databases on the ORACLE platform

Subject of Research. The paper deals with the research of transformations used in up-to-date symmetric algorithms aimed at definition of the most high-speed ways of their realization on the graphics processor with the use of CUDA and OpenCL technologies. Method. To achieve this goal, we considered LSX and ARX structures of block algorithms on the example of the following ciphers: AES, «Kuznyechik», LEA, Rectangle, Simon and Speck. The main types of transformations were detected, which include: multiplication in Galois fields, the use of lookup tables, bitwise operations, long number addition and data exchange with the global memory as an integral part of the calculations on graphics devices. The variants of the implementation of these calculations were considered and synthetic tests were carried out to determine their execution time. Main Results. The best ways for implementation of these transformations were determined. When performing multiplication in Galois fields, if one of the multipliers is constant, the best time was shown by the method using the pre-calculation table. It was also found that the most effective in terms of speed is the storage of replacement tables in shared memory and the implementation of bitwise operations with the division of input data into 8-bit elements, as in the case of long numbers addition. The result approbation was carried out by CLEFIA algorithm realization.The encryption time of 1 GB of data was 1542 mc. This result is 16 times less than the encryption time on the general-purpose processor. The application of realization variants for studied transformations that show the worst time results during synthetic tests on graphics processors gives fourfold speed increase compared with the central processor. Practical Relevance. The study results are applicable for the speedy and efficient use of graphics processors in the implementation of existing encryption algorithms. The results can become the basis  for the development of new encryption algorithms with the use of graphics processors.

We have carried out the analysis of commercial and free software for support and organization of  cloud computing, outlined the advantages and disadvantages of existing methods for reliability and security improvement of computing systems. Most of the existing systems do not take into account a number of factors that affect the safety, reliability and performance of calculations, the complexity of adaptation to changing requirements and environmental conditions. The work objective is formulated consisting in selection of cloud computing system architecture that provides maximum satisfaction of requests with different priority level, coming both from users and from services of the system itself. To solve this problem we propose a method of the system configuring  for cloud services based on the model of a neuro-fuzzy system. The method gives the possibility to increase the productivity of users' requests providing the reliability and security of the processed information in special-purpose and dual-use systems. The architecture of the neuro-fuzzy network is developed, its input and output parameters are determined. Applying the proposed models, the configuration of a cloud information system designed to solve certain groups of tasks is carried out as an example. The decision  result was a distribution matrix of system resources for serving of different task groups.

Subject of Research. The present paper is devoted to the attacks detection problem  on voice biometric systems (spoofing-attacks) in telephone channel. Nowadays, spoofing detection is under the high interest in the field of voice speaker authentication. The results of the Automatic Speaker Verification Spoofing and Countermeasures Challenge in 2015 and 2017 dedicated to isolated task of spoofing detection confirmed the high perspectives in detection of unknown types of attacks in microphone channel. However, similar task in telephone channel remains extremely relevant, for example, in the banking sector. Method. The aim of the work was to study the applicability of deep learning approach for described problem solution, in particular, convolutional neural networks with the Max-Feature-Map activation function.Main Results.The experiments performed for real telephone attacks showed insufficient efficiency of the systems trained on data with emulated telephone channel. That is why, the database of real spoofing attacks in telephone channel was collected. The best system demonstrated 1.5% equal error rate (EER) on a subset of replay attacks, 1.7% for voice conversion attacks, and 2.8% for attacks with voice synthesis. Experiments show the need to consider different recording conditions, due to the great number of factors that have the influence on the channel. Practical Relevance.The results of the work can be applied in the field of voice biometrics. The presented methods can be used in systems of automatic speaker verification and identification for detection of spoofing attacks on them.

A statistical evaluation of the control unit computer model for multi-agent robotic systems is carried out. An algorithm is considered that realizes the achievement of a single goal by robots-agents – to cross the intersection at the maximum speed. Let such algorithm be called an "algorithm for conflict solutions". The paper presents the study of the dependence of the vehicle appearance probability effect from each intersection side on the maximum speed of the intersection crossing. The efficiency of the applied algorithm is evaluated at the intersections of various types, for example: four-way intersection, T-junction, Y-shaped intersection. The efficiency estimation was performed by a full factorial experiment on the study of the "algorithm for conflict solutions" operation by the unmanned vehicle control unit. The basic idea of a full factorial experiment is that the researched object is considered as a "black box". Thus, the effect of input parameters (factors) on the response function is studied. The main benefit of full factorial experiment application is the construction of an experiment planning matrix that contains all possible combinations of factors. This approach gave the possibility to identify those combinations of factors that have the greatest and the least effect on the response function. The received results testify to the possibility of the algorithm for conflict solutions operation for intersection of various types of roads. The algorithm shortcomings were revealed. In future it is expected to use the obtained results to assess the information security of the multi-agent robotic system with decentralized and centralized control.

Subject of Research.The paper proposes principles, conditions and technical solutions of the creation process for moments of inertia of spherical rotors based on the mass redistribution of functional coatings formed on the rotor surface. We study the formation technology of the required values and the ratio of the axial and equatorial moments of inertia of the spherical rotor that is a main constructive element of electrostatic gyro. Traditional forming methods of the moments of inertia of solid spherical rotors are based on embedding reinforcing elements made of materials with higher density than the substrate in the body of the rotor. It can be realized by pressing the wire segments or by diffusion welding of the rotor assembly units. In this case the rotor consists of several components, and reinforcing elements, embedded in the body of the rotor create inhomogeneities and anisotropy of the assembly properties. This fact reduces the accuracy and negatively affects the dynamics of the rotor in the suspension. Existing methods also have limitations in terms of the possibility of nonmetallic material application for production of the rotor. Method. We propose an alternative method for formation of rotor moment of inertia based on the mass redistribution of thin-film functional coatings formed on rotor surface. It can be used for metals and nonmetallic materials. Mathematical models for realization of the proposed method are presented. Main Results. The developed mathematical models determine the dependence of moments of inertia on the geometric parameters of rotor elements and reveal significant factors controlling the process of formation of moments of inertia. Technical solutions for different rotor configurations are considered. A rotor can be realized as an ellipsoid of rotation, a ball with removed material in the shape of a spherical belt and a ball with an equatorial groove, with the following spherical-shape recovery during coating deposition. Practical Relevance. We present comparative analysis of the application efficiency for considered configurations and practical data, received from the production of rotors made of various materials.The mathematical models are developed that determine the variation ranges of the rotor geometric parameters and expand the technological capabilities of the formation process for moments of inertia through the use of various alternative versions of the manufacture of rotors.

The paper briefly provides the results of developing an information retrieval system prototype for scientific and educational content based on linked open data. The authors proposed a solution for the problem of information acquisition on publications from decentralized sources. The paper also presents the system functioning principle and shortly describes the architecture of the system prototype. A feature of the developed prototype is the provision of the ability to search for scientific publications taking into account the professional interests of the end user. The aim of this work is spreading a word and increasing of the linked open data popularity in the academia.

The paper considers the problem of thematic segmentation of extended texts aimed at the support of technical systems designer operation. The example shows that different segmentation algorithms allocate meaningfully different text fragments, and the composition of algorithms in a classical form, that is, by summarizing the results in order to single out the best one, seems to be wrong. At the same time, the simultaneous demonstration of several versions of the thematic segmentation enables the reader to obtain an integral representation of the text structure, thereby facilitating the choice of an effective strategy for mastering the text. The created system of  thematic segmentation visualization of extended texts is described, providing the user to select and analyze not the whole text, but only fragments corresponding to his current information needs. The system gives the possibility to view simultaneously the results of text segmentation performed by various algorithms. Thus, the user's abilities for quick and efficient analysis and capturing of a large amount of textual information are enhanced.             

The paper considers the stability and degradation of holograms recorded in the photopolymerized nanocomposite both during storage and under external influences –heating up to the glass transition temperature of the polymer matrix and exposure to ultraviolet radiation. The compositions with different nanoparticles are compared; the difference in the thermal stability of the recorded holograms is shown; the optimum component ratios ensuring the lowest degradation are found. Holograms are recorded on a nanocomposite material that is a liquid photocurable monomer composition containing ZnO or SiO2 nanoparticles and photosensitizers.       

A method of pulse-width control of the high power full-bridge converter with widely varied supply voltage is proposed. The method is based on the carrier frequency variation and is implemented as proportional-integral controller with adjustable parameters. The proposed method allows improving dynamic characteristics of the system and limiting of maximum current commuted by transistors. The proposed control law allows receiving desired load voltage.

Subject of Research.The paper deals with robustness estimation of free motion deviations in aperiodic continuous systemsto parameter variations of the state matrix. Methods. The problem is solved with the state space approach and the sensitivity theory methods. Main Results. An upper bound estimation of trajectory deviations for aperiodic continuous systems is obtained. The equations contain the condition number of the eigenvectors matrix, that is the basis value for the robustness estimation of the deviations with the sensitivity theory methods. Practical Relevance. The results can be used for analysis of uncertain aperiodic continuous systems.