Subject of Research. The paper presents experimental determination of the main shrinkage direction caused by photopolymerization during holographic recording in Bayfol HX material. Method. The determination method for the main shrinkage direction is based on registration of the change in volume holograms characteristics (period, the orientation of isophase planes relative to material surfaces and hologram thickness) caused by the shrinkage. For the implementation of this method a 2D-model is presented which describes shrinkage as a vector. The effect of the shrinkage on characteristics of holograms is evaluated based on geometrical laws. We performed modeling of the shrinkage with different directions and determined its effect on a variety of arbitrarily oriented holograms-gratings. Namely, the cases of isotropic shrinkage, as well as shrinkage in the direction of the material surfaces, the lattice vector and the isophase planes were considered. The experiment is carried out involving a simultaneous recording of two total internal reflection holograms in a photopolymerizable Bayfol HX composite. The changes of their characteristics make it possible to determine clearly the main shrinkage direction. Main Results. The main shrinkage direction has been determined along the less side of the material (considering thickness). However, the experiment has demonstrated a deviation of this direction along the lattice vector as well. Practical Relevance. The developed model and the experimental method allow for taking into account the shrinkage in Bayfol HX while modeling of photopolymerization and multicomponent diffusion in this material. The studied technique also facilitates predictions of hologram characteristics after the shrinkage aimed at its compensation.

Subject of Research. The paper proposes an approach to aerial mapping that provides the photogrammetric quality of images necessary for creating orthophotoplans with high cartographic similarity. The topicality of the approach is determined by cartographic similarity reduction of the area orthophotoplans in case of automated processing of images obtained from an unmanned aerial vehicle in disturbed flight conditions. In particular, artifacts are formed on orthophotoplans that reduce the area representation adequacy in the image and prevent the correct visual interpretation of images. We propose an approach that provides planned area images, and after their automated processing orthophotoplans of places are formed with improved cartographic similarity. Method. The aerial mapping approach is based on the idea of applying the arrangement of optical-electronic cameras that analyze navigation measurement data. The proposed approach gives the possibility to minimize image perspective geometric distortions on pitch, roll and yaw that occur when an unmanned aircraft turns around during flight. Consequently, the conditions for planned aerial photography are met and, as a result, aerial images with the required photogrammetric quality are obtained. The absence of perspective geometric distortions in the images provides the creation of the area orthophotoplan without visible distortions. Main Results. A model of an aerial image geometric distortions has been developed that analyzes the effect of the optical- electronic camera sight line deviation from the direction to nadir on the occurrence of perspective geometric image distortions. Calculation results are presented for parameters of the frame projection on the earth surface for lenses with different angular fields of view. Following on from the results, an approach to aerial mapping is proposed using an optical-electronic camera arrangement that provides planned area images in the conditions of an unmanned aerial vehicle maneuvering. Practical Relevance. The arrangement of optoelectronic cameras in aerial mapping makes it possible to get planned images without additional technical means of shooting equipment stabilization and ensures the aerodynamic quality of an unmanned aerial vehicle airframe. In addition, the application of the proposed technical solution maintains the transfer characteristics of lenses of optoelectronic cameras installed in the body of an unmanned aerial vehicle and functioning in conditions of significant changes in the ambient temperature. The results of experiments demonstrate an increase in the cartographic similarity of orthophotoplans when selecting images obtained by applying the arrangement of optoelectronic cameras for aerial photography.

Subject of Research. The paper considers the issues of objective quality assessment of computer-generated Fresnel holograms and reconstructed binary object images. Method. The work is performed by the method of projection holographic photolithography based on computer-generated Fresnel holograms. The synthesis of holograms was carried out by mathematical modeling of the physical processes of hologram recording and reconstruction in the original software package using the following parameters: the binary object characteristic size of 80 × 80 nm, laser wavelength of 13.5 nm, hologram pixel size of 20 × 20 nm, the distance between an object and hologram planes equal to 20.4 μm, reference wave incidence angle of 14°42′. The hologram synthesis for each object under research was carried out for the case of two different synthesis setup parameters. The reconstructed images of these objects were compared by three methods: the peak signal-to-noise ratio calculation method, the structural similarity index calculation method, and the method of image quality assessment based on the calculation of the number of levels at the threshold image processing, which is an imitation of photoresist response to actinic radiation exposure. Main Results. Diffraction-based criterion, traditionally applied in optics, is proven to be the most relevant for the quality evaluation of projection photolithographic systems, including systems based on computer-generated holograms. It is established that the methods based on the calculation of the structural similarity index and on estimation of the number of levels at the threshold image processing are the most suitable methods for assessing the reconstructed image quality in the field of projection holographic photolithography. Moreover, the second method does not require any additional calculations. Practical Relevance. Application of an adequate quality assessment method makes it possible to compare quickly and objectively the reconstructed images of the same objects obtained for various parameters of the synthesis setup and select the object representation form and the hologram synthesis setup that is the most suitable for a particular task.

Subject of Research. We propose a solution to the problem of nondestructive testing formacro- and microstructure of Baltic amber by optical analysis. The considered method provides for high-quality characteristics of materials and amber-made products. Method. The proposed approach was based on the analysis of fluorescence spectra using the “Fluorat-02-Panorama” analyzer. Microstructure study was carried out using Leica DMLM confocal microscope with a resolution less than 1 μm included in Renishaw InVia Reflex laboratory equipment. For macrostructure study, we proposed “Regula” 4305M/MH universal video spectral comparator with “Regula” 100X viewing magnifier. Samples of processed and unprocessed amber from the Palmniken Deposit (Kaliningrad, Russian Federation) with different transparency were studied. Main Results. The fluorescence spectra of Baltic amber with different transparency are presented. It is found that the less transparent samples are characterized by lower fluorescence intensity. We make it clear that the fluorescence spectra of transparent amber with transparency up to 75 % have the form of a wide cascade band with three peaks at the peak of intensity in the range of 650–800 nm. It is noted that the qualitative color characteristics of amber fluorescence have an additive character. It is shown that the destruction of amber can reveal internal and external defects, establish the degree of transparency and distribution of opaque areas in the source material and products made of it. Practical Relevance. The proposed method may be of interest in the field of materials science, research related to identification processes, processing of manufacturing amber-made products. The performed research can be used in the synthesis of high-molecular compounds, in the study of a wide class of organic materials and in the design of organic light emitting diodes.

Subject of Research. Fiber optic measurement systems are widely used in various industries. Most of these systems are fiber optic devices for detecting physical quantities. The development and creation of a measurement system for determination of the location and bends of extended objects in 3D space are actual at the moment. We propose the implementation of the sensitive part of the fiber optic measurement system based on seven single-mode fibers with an array of fiber Bragg gratings fixed to each other. Method. The method for determining the position and bends of extended objects in space is based on finding the level of axial deformation (compression, tension) of the fiber Bragg gratings during bending, and provides the calculation of the curvature direction and magnitude. Further reconstruction of the curve in space is realized by solving a system of differential equations with given initial conditions containing Frenet-Serre formulas. Main Results. The paper presents experiment results on writing fiber Bragg grating arrays into single-mode optical fibers, taking into account the features of the optical scheme and the source spectrum. The design and prototype of the fiber optic measurement system are developed. The results on the reconstruction of the shape based on experimental data are obtained. Practical Relevance. A special feature of this system is the fiber Bragg grating arrays formed in a wide range of wavelengths. Each Bragg grating corresponds to its own reflection wavelength, providing a sensitive part 1 m long. The geometry of the structure is based on seven fiber-optic armored microcables twisted with a given lay length during manufacturing, and provides the measurement of the kink value and direction.

Subject of Research. The topical spectroscopy inverse problem is considered: the recovery of a discrete (line) spectrum from the measured continuous spectrum and the spectrometer response (instrument, hardware, spread) function in the presence of noise. Method. The problem is reduced to solving a system of linear-nonlinear equations with respect to the intensities of lines entering linearly and the frequencies of lines entering nonlinearly in the spectrum. To solve the system of linear-nonlinear equations, an integral approximation algorithm is developed that combines the solution of a linear integral equation and a system of linear algebraic equations without solving non-linear equations. Main Results. The proposed solution makes it possible to determine the number of lines in the spectrum and their parameters and is confirmed by the solution of numerical examples. Practical Relevance. The proposed algorithm provides the increase of spectrometer resolution (resolve close lines and isolate weak lines from noise) by applying mathematical-computer processing of the discrete spectrum.

The paper considers robust stability study of continuous and discrete interval dynamic systems by algebraic method. The original robustness results obtained for continuous and discrete linear interval dynamic systems within the algebraic direction of robustness stability are presented. The author formulated and proved the basic theorem on the robustness of linear continuous dynamic system with interval elements of the right-hand part matrix, which is determined through the separate angular coefficients of characteristic polynomial of the system. The basic theorem is proved on the basis of a lemma on the separative coefficients of the characteristic polynomial obtained by optimization methods of nonlinear programming on multiple interval elements of the system matrix. Their possible values can be the upper or lower limits of the corresponding interval or zero. A clarification note to the basic theorem for continuous systems is formulated. The idea lies in the need for a complete set of four angular polynomials for the robustness stability of the system, excluding multiple cases of the characteristic polynomial, when the set of Kharitonov polynomials degenerates and will consist of the less required four different polynomials. The theorem is obtained on the necessary and sufficient conditions of robustness stability for the polyhedron of interval matrices. A discrete analogue of the Kharitonov theorem is obtained for discrete systems. The algorithm of robustness stability determination for discrete interval dynamic systems is presented. Comparative characteristics of the results obtained in the works of well-known authors having studied the algebraic trend of robust stability problem are considered. They show the distinctive feature of this method, which consists in consideration of interval matrices of general type. The validity of the method is tested on the known counterexamples to Bialas’s theorem, as well as the other researchers studying robustness problems of interval dynamic systems.

Subject of Research. The paper considers navigation system for mobile robots by building a map of the environment using Simultaneous Localization and Mapping algorithm and converting the 3D map collected by INTEL Realsense Depth camera into a 2D-cost map. Method. Real-Time Appearance-Based Mapping was used for building a virtual 3D map of the environment. A binary map was obtained by projecting the 3D map on a plane. The D* algorithm was applied on the binary map for planning a global path to the goal. The Dynamic-Window Approach was used as a local planner. Main Results. A point cloud of the environment was created and converted to a 2D map. A robot was safely navigated to the desired location. Practical Relevance. The proposed approach is fast and reliable and can be used for indoor navigation (factories and companies). Since the map needs to be designed only once, the calculation can be handled by CPU without any need for graphics processing unit.

The paper provides comparative analysis of direct and indirect methods for assessing the size and morphological characteristics of niosome dispersions. Niosome sizes vary over a wide range: from 20 nm to 10 μm and more. The vesicle shape can also vary from perfectly spherical to elliptical and complexly curved in the case of aggregation. The size and shape of large particles with a diameter greater than 1 μm can be assessed by light microscopy. To study smaller vesicles, about 0.1–0.5 μm, it is advisable to use the technique of dynamic light scattering. Photometric method is reasonable to be used for an indirect assessment of the size of niosome vesicles in the range of 40–130 nm. For surface morphology study of the smallest niosomes, the method of scanning electron microscopy seems to be optimal.

Subject of Research. The paper presents a review of the currently existing basic types of simple semantic networks. We highlight and describe distinguishing features of relations that determine the type of semantic network and the methods of presenting information used in it. Classification of simple semantic networks and corresponding methods by the area of activity has been carried out. The known results are clarified and expanded. Method. The study and analysis of scientific publications on the problem of data representation in information systems provided the identification of distinctive features of the methods related to different types of simple semantic network. Main Results. The concept of a simple semantic network is considered. The mechanisms for the following methods of presenting information in simple semantic networks are described: IS-A, PART-OF, statistical technology, modernized IS-A method; case random, case deterministic, attribute methods, probability of the jth concept occurrence; using the weights of relations between concepts, the proportion of duplicated elements, the importance of concepts; based on the general properties of sets and production rules; setting time frames in relations. The review is based on the Russian-language publications. Practical Relevance. The research results clarify and bring together already known findings that makes it possible to solve the problem of further development of methods for presenting information in semantic networks.

Subject of Research. The paper studies minimum-sized deterministic finite automata inferring problem. A hybrid method is developed and implemented reducing the given problem to Boolean satisfiability (SAT) technique and at the same time applying a counterexample guided abstraction refinement approach. Method. It is proposed to use not all given behavior examples as training data but start with some subset of them and build a consistent automaton, using SAT- based automata inferring method. Then the built automaton is checked against the complete set of behavior examples. The examples not consistent with the automaton are counterexamples. Some subset of counterexamples is added to the current training data and the process is being repeated. Main Results. The proposed method is implemented as a part of deterministic finite automata inferring tool in Python language. Experimental comparison of the developed method and the SAT-based method without abstraction refinement is carried out. Practical Relevance. Experimental research has shown that the developed method is reasonable for application if the number of behavior examples is large enough, at least, two hundred times exceeds the number of the automaton states, and, therefore, the Boolean formula being created contains tens and hundreds of millions of clauses.

Subject of Research. Image matching and classification methods, as well as synchronous location and mapping, are widely used on embedded and mobile devices. Their most resource-intensive part is the detection and description of the image key points. In case of classical methods for detection and description of key points they can be executed in real time on mobile devices but for modern neural network methods with better quality, such approach is difficult due to trading off performance. Thus, the issue of speeding for neural network models applied for the detection and description of key points is currently topical. The subject of research is distillation as one of the methods for reducing neural network models. The aim of the study is to obtain more compact model for detection and description of key points and a description of the procedure for this model design. Method. We proposed a method for pairing the original and more compact new model for its subsequent training on the output values of the original model. In this regard, the new model is learned to reconstruct the output of the original model without using image labels. Both networks accept identical images as input. Main Results. Neural network distillation method for detection and description of key points is tested. The objective function and training parameters that provide the best results in the framework of the study are proposed. A new data set is created for testing key point detection methods, and a new quality indicator of the allocated key points and their corresponding local features is added. New model training in the way suggested with the same number of parameters, shows greater accuracy in key points compared to the original model. A new model with a significantly smaller number of parameters shows the accuracy of point matching close to the accuracy of the original model. Practical Relevance. More compact model for detection and description of image key points is created applying the proposed method. The model is applicable on embedded and mobile devices for synchronous location and mapping. Such model application can also increase the service efficiency of the image search on the server side.

Subject of Research. The paper presents research of approaches to portable software development at the level of binary and source code. We study such factors affecting portability as compatibility of target platforms at the level of software and binary application interfaces, standardization of programming languages, software architecture, the functionality of software target platforms and software tools. Modern approaches for software portability based on virtual runtimes for Java and the .NET platform are considered. Method. A method is proposed for software portability based on two- stage compilation and an architecture description language application for translator configuration. The method gives the possibility to solve the software portability problem at the level of program execution environment. We also present a new approach to self-tuning runtime implementation with such configuration parameters as architecture-dependent metadata — descriptions of target platforms. To generate a binary image of the runtime environment for a target platform, its source code is not required. Image generation is performed based on metadata that is part of an existing image used as a builder utility. Main Results. Implementation requirements for the program execution environment and its architecture at the level of functional components are determined. The novel approach for the runtime implementation is proposed which ensures portability without recompilation from the source code of both user applications and the runtime environment. A script for the runtime environment application has been developed to generate its binary image aimed at a target platform. Practical Relevance. Binary portability of the program execution environment allows reducing labor costs for cross-platform applications.

The issue of effective detection and classification of various traffic signs is studied. The two-stage method is proposed for creation of holistic model with end-to-end solution. The first stage includes implementation of effective localization of traffic signs by YOLO version 3 algorithm (You Only Look Once). At the first stage the traffic signs are grouped into four categories according to their shapes. At the second stage, an accurate classification of the located traffic signs is performed into one of the forty-three predefined categories. The second stage is based on another model with one convolutional neural layer. The model for detection of traffic signs was trained on German Traffic Sign Detection Benchmark (GTSDB) with 630 and 111 RGB images for training and validation, respectively. Сlassification model was trained on German Traffic Sign Recognition Benchmark (GTSRB) with 66000 RGB images on pure “numpy” library with 19 × 19 dimension of convolutional layer filters and reached 0.868 accuracy on testing dataset. The experimental results illustrated that the training of the first model deep network with only four categories for location of traffic signs produced high mAP (mean Average Precision) accuracy reaching 97.22 %. Additional convolutional layer of the second model applied for final classification creates efficient entire system. Experiments on processing video files demonstrated frames per second (FMS) between thirty-six and sixty-one that makes the system feasible for real time applications. The frames per second depended on the number of traffic signs to be detected and classified in every single frame in the range from six to one.

Subject of Research. The paper presents the study of the U-Net architecture neural network applicability to localization problem of image modifications. The implemented method provides the detecting of the modified image and getting a mask of the changed area. Method. The proposed method was based on deep machine learning – a neural network. U-Net neural network architecture was studied. The training dataset was created as a basis for model training with original images and images modified using a graphical editor. The implemented method represents image as a set of pixels. Main Results. The trained model has shown a high level of brightness recognition for image modifications, up to 80 %, and up to 64 % for copy-shift. Practical Relevance. The result can be practically applicable in the forensics for recognition of modified image blocks and for copyright protection.

Subject of Research. The research of deterministic systems is a topical problem of natural science. The paper presents an approach for behavior study of the deterministic systems. The work is aimed at creation of the evolution equation for deterministic systems, which shows that part of the macroscopic processes complies with quantum logic. Method. A new algebraic approach is proposed based on non-commutative algebra. It is shown that for any deterministic system in case of setting its change for a short time period, it is possible to create a system of differential equations describing the evolution of a given system in time. Implemented apparatus of non-commutative multiplication is an alternative to the operator calculus for quantum mechanics. Main Results. An associative non-commutative ring is built describing the evolution of arbitrary deterministic system. The proposed algebra is an isomorphic Heisenberg algebra. It is shown that all elements of algebraic rings are functions of numerical variables unlike the mathematical apparatus of quantum mechanics and, therefore, it is possible to give them different physical meaning. Practical Relevance. An example of differential equation creation is considered describing the motion of a classical particle in the presence of random forces. The obtained equation describes the probability density of a classical particle location at an arbitrary point of time in phase space.

Subject of Research. The paper deals with the development of methodological principles, scientific basis for the recognition of piece specific small parts and finished production items on a thin gas layer. The proposed principle is based on the use of a layer as a carrier and recognizing main element of the technical pneumatic system. Together with the design features of the working surfaces of devices, the creation of universal pneumatic equipment is provided. The developed equipment is able to solve successfully the following tasks: control, classification, sorting, rejection and orientation of the production item. The principle of recognition is described. Characteristic elements of the technical pneumatic system are considered. Specific parts and their classification, types of work surfaces and device circuits with certain functional capabilities are presented. Method. The elements of pattern recognition theory were used. In particular, a new recognition method was proposed by a generalized criterion (specific load). Two orientation keys were obtained (bearing surface area of the product and its mass). A new technical pneumatic system was of the form: “pneumatic chamber–device working surface–thin gas layer–production item”. It formed the basis of the proposed class of devices with certain functional capabilities. Main Results. It is shown that pneumatic equipment based on the presented technical pneumatic system has wide functional capabilities: versatility, multifunctionality, the ability to manipulate specific production items, flexibility when switching from one standard size of parts to another. Practical Relevance. Modeling and coding of the presented system is the first step for software product development aimed at automated design of modern pneumatic equipment with certain functional capabilities.

Subject of Research. The paper presents a new approach to the analysis of experimental data on walking. It involves the application of gear ratio statistics. The research is based on the experimental data on flexion-extension-rotation movement of knee joint that has been obtained in the laboratory of kinesiology and biomechanics of Tartu University, Estonia. Methods. Angular velocities have been calculated for each of the motion data phases. Temporal values of angular velocity sign changes have been represented as a random process. The role of the Poisson distribution for modeling distribution of transition points through zero has been considered. Correlation functions and spectral densities of these processes have been created. The role of uniform distribution in the estimation of gear ratios has been described. The contribution of cruciate ligaments in the movement transmission has been studied. Main Results. The average values and variance of gear ratios have been calculated as a result of data processing by Poisson and Fischer statistics. An elastic transmission mechanism model for flexion-extension-rotation of knee joint movement using the gear ratio and features of helical anisotropy in application to the mechanics of cruciate ligaments has been proposed. Practical Relevance. The work is aimed at the search for solutions to modernization problems of elastic actuators used in design of knee orthoses.

Subject of Research. The paper considers the main quantitative characteristics of microphone arrays in their performance analysis and beamforming algorithms applied for their study. Methods. The principal characteristics, calculation approaches and evaluations were examined. The most widespread beamforming algorithms were analyzed, such as: Delay-and-Sum (DAS), minimum variance distortionless response (MVDR), Frost’s algorithm or linearly constrained minimum variance (LCMV), generalized sidelobe canceller (GSC). The calculations and comparative analysis of the algorithms were performed in Matlab simulation environment. The following quantitative characteristics were obtained: signal-to-noise ratio, signal-interference-noise ratio, directivity index, directivity characteristics, and beamwidth. Main Results. Algorithm comparison results are presented on the example of a linear microphone array. The linearly constrained minimum variance algorithm has shown the most satisfactory results. The simulation results must be clarified by real experiments. Practical Relevance. The results of the work can be used for analysis of more complex microphone arrays and acoustic structures, such as microphone arrays with “floating” geometry and distributed microphone arrays.

Subject of Research. The paper reveals the possibility of using animated biometric QR code for simplification of people monitoring and identifying in service, identification badges and passes. Method. The methods are based on image processing and barcoding procedures applying QR codes. Main Results. The color animated biometric QR code is attached to the original 16-digit code. While opening the QR code, all information embedded in it is automatically displayed and can be viewed visually. The color code contains a splash screen with an alphanumeric 16-digit code, a color photo and the necessary information about the bearer. Practical Relevance. The animated biometric QR code can be implemented on the basis of electronic badges, as well as placed on a smartphone and used for identifying people. That sort of QR code uses minimum personal information content and can be applied autonomously without connecting to a computer network.

Subject of Research. The paper presents research of photoactinic radiation effect on refractive indice of organic nonlinear optical co-crystals: 2.6-diaminopyridine-4-nitrophenol and 4-aminopyridine-4-nitrophenol. Method. The research technique included prolonged exposure of the organic nonlinear optical co-crystals of aminopyridine-nitrophenol to a light-emitting diode at a wavelength of 405 nm. In the exposure process of the studied co-crystals a sequential measurement of the refractive indices was carried out by Olympus STM6 instrumental microscope. Main Results. The increase in values of the refractive indices is observed for both co-crystals examined during the long photobleaching. We present circle diagrams for refractive indices of the organic aminopyridine-nitrophenol co-crystals under study. Practical Relevance. The results obtained show the possibility of creating structures based on organic co-crystals of aminopyridine-nitrophenol with a given distribution of refractive indices (periodic lattice and photonic crystal structure).