Recognition of human emotions by facial expressions is an important research problem that covers many areas and disciplines, such as computer vision, artificial intelligence, medicine, psychology and security. This paper provides an analytical overview of video facial expression databases and approaches to recognition emotions by facial expressions, which include three main stages of image analysis, such as pre-processing, feature extraction and classification. The paper presents both traditional approaches to recognition of human emotions by visual facial features, and approaches based on deep learning using deep neural networks. We give the current results of some existing algorithms. In the review of scientific and technical literature we empathized mainly the sources containing theoretical and research information of the methods under consideration, as well as comparison of traditional methods and methods based on deep neural networks, which were supported by experimental studies. Analysis of scientific and technical literature describing methods and algorithms for study and recognition of facial expressions, as well as the results of world scientific research, have shown that traditional methods for classification of facial expressions are second in speed and accuracy to artificial neural networks. The main contribution of this review is providing a common understanding of modern approaches to recognition of facial expressions, which will enable new researchers to understand the main components and trends in the field of recognition of facial expressions. Moreover, comparison of world scientific findings has shown that a combination of traditional approaches and approaches based on deep neural networks achieves better classification accuracy, but artificial neural networks are the best classification methods. The paper may be useful to specialists and researchers in the field of computer vision.

Subject of Research. The paper presents experimental study results of surface morphology and structural and optical properties of sapphire AlN films obtained by pulsed laser spraying. Method. Thin AlN films on sapphire were used as experimental samples. The preparation of AlN films was carried out using a combined installation of ion-beam and pulsed laser radiation. The deposition process was performed by sputtering a rotating aluminum target with 532 nm wavelength AYG: Nd3+ laser in the atmosphere of very pure nitrogen at the pressure of 3 and 4 Pa. The energy density of the laser pulse was 4 J/cm2 with a pulse duration of 15 ns and a pulse repetition rate of 15 Hz. The distance from the target surface to the sapphire substrate was 50 mm; the substrate temperature was 600 °C. Main Results. Using scanning electron microscopy and energy dispersive analysis, it was found that AlN films obtained at the nitrogen pressure in a vacuum chamber of 4 Pa have a composition more related to stoichiometric than AlN films obtained at the nitrogen pressure in a vacuum chamber of 3 Pa. The optical spectroscopy was used to study the transmission spectra of the samples under research. It was determined that the maximum transmission coefficient values of AlN films obtained at the nitrogen pressure in the vacuum chamber of 3 Pa (95.12 %) and 4 Pa (97.65 %) are within the wavelength range of 400–410 nm. The transmittance in the studied wavelength range of 300–1100 μm is at least 87 %, which characterizes the obtained film samples as optically transparent. Practical Relevance. The studied thin AlN films can be used as a buffer layer in optoelectronic devices, including the case of creating light-emitting diodes based on GaN and AlxGa1–xN of short-wave visible light and white-emitting devices.

Subject of Research. The paper presents testing and evaluation of the spectral method potential capabilities in relation to the study of human blood serum in normal and in patients with multiple myeloma. The study of samples of native and lyophilized serum is carried out in comparison with the spectral characteristics of aqueous extracts of animal muscle sarcoplasm. Method. A non-destructive diffuse reflection electron spectroscopy method with a vertical beam path in the wavelength range of 200–700 nm in the absorption format was used. Main Results. In contrast to the native donor serum, a band of mucopolysaccharides (410–415 nm) of different intensity has been observed in the spectra of samples of animal tissue sarcoplasm extracts. This band appeared in the spectra of donor serum after lyophilization. That is why the presence of the band of mucopolysaccharides in the patients’ serum spectra is associated with reduced moisture binding capacity of the protein-polysaccharide complex, which, in turn, is due to the features of protein secondary structure in different forms of multiple myeloma. Practical Relevance. The peculiarities in the similarities and differences between blood serum spectra of donors and patients give reason to believe that the method of diffuse reflection electron spectroscopy, that does not require a lot of material and preliminary sample preparation, can be promising as a rapid tool for additional initial diagnosis and the treatment process monitoring of multiple myeloma and other lymphoproliferative diseases.

Subject of Research. We present a solution to the problem of amber (succinite) identification as an example of natural polymer material of organic origin. The solution is based on the obtained Raman spectra. The proposed method makes it possible to obtain both real and elemental compositions. Method. The study of succinite spectra was performed by the method of Raman spectroscopy (Fourier Transform–Raman spectroscopy). Renishaw InVia Reflex equipment with a Leica DMLM microscope was used for the study. Samples of amber from the Palmniken Deposit from Kaliningrad in the Russian Federation were used as the objects under study. Samples of various degrees of transparency were selected. Main Results. The Raman spectroscopy data for the Raman scattering spectra of succinite are obtained and presented in comparison. It was found that succinite (amber) of the Palmniken Deposit from Kaliningrad is an organic unsaturated carbon–chain homopolymer with various valence oscillations of aliphatic CH2- and CH3-groups, containing heteroatoms C=C and CH in the main chain with valence in RNS=CH2 and deformation in trans RHC=CHR′ oscillations with chemical side chains of up to 8 subgroups. Three main connections are experimentally identified on the obtained Raman spectra, which can be used as characteristic features for identification and diagnostics of the Palmniken Deposit succinite. Practical Relevance. The proposed method can be of interest in the field of the theory of science materials knowledge, research related to the identification processes, processing of production of amber products. The performed research is applicable in the synthesis of high–molecular compounds, in issues related to the development and spread of various applications of organic materials, in particular, succinite.

Subject of Research. The paper considers a flight control system for the longitudinal movement of an aircraft with a human-pilot in a closed loop. Computer simulation setting of the selected pilot behavioral model is carried out in the compensatory tracking mode. The parameters correspond to the optimal behavior of the pilot providing the best aircraft dynamic characteristics. Method. Padé approximation was used when creating a computer program for calculations.Frequency and optimal methods, and handling qualities scale were used for quality assessment of the control system dynamic properties. Main Results. Numerical values of the pilot behavior model parameters are found on the example of a normal aerodynamic scheme, in which the elevator serves as an element of the tail unit. The numerical values estimation of the pilot model parameters is performed. The simulation results are given. Practical Relevance. The proposed approach to the pilot behavior simulating process during piloting simplifies, accelerates, and reduces the cost of an aircraft test program. Software simulation can be used at the test stage and before tests on flight simulators and will give the possibility to identify unsatisfactory handling characteristics of the aircraft and its control system and quickly correct them.

Development of drug delivery systems is one of the high-priority areas in pharmaceutical technologies. Currently, most of the largest pharmaceutical companies are developing delivery systems, both for new drugs and for already existing ones. Oncology has been and still remains one of the leading application areas for these systems. A variety of problems to be solved in the development of delivery systems has led to the emergence of numerous options for such systems. Each of these options has its pros and cons. The specificity of drug delivery systems and their diversity has led to the necessity of information systematization about their physical and technological characteristics and applicability in clinical practice. This review generalizes and systematizes information about modern targeted delivery systems for medicinal compounds with low bioavailability that is described in the scientific literature and is used in modern pharmaceutical technology. Particular importance is given to the trends of nanoscale delivery systems development for various therapeutic drugs that can penetrate protective barriers of body, achieve sustained controlled release, and are also promising for delivery to target cells. Nanoscale drug delivery systems have higher potential for pharmaceutical and medical industries. The following nanoscale systems for drug delivery were identified: nanoemulsions, nanocapsules, nanoliposomes (including exosomes, virosomes, and other modifications of traditional liposomes), dendrimers, and carriers based on cells and peptides. Their main technological and pharmacological characteristics were given, and the prospects for their clinical use were considered. The base methods of each drug delivery systems formation were also described. It has been shown that the interest in modifications of liposomal systems (exasoms) as well as in dendrimers and cell-based delivery systems increases every year.

The paper deals with denial-of-service attacks on the Internet of things networks with the MQTT Protocol. This Protocol is intended for data multicasting, including telemetry, that is why it can be potentially used for denial-of-service attacks. A review of studies already carried out on this issue is presented. In contrast to other approaches, the author has tested a hypothesis about potential application of not only publish messages for attacks, but also other types of messages, such as connect and subscribe. Analysis was carried out for identification of the impact of multiple message processing on system performance. An experimental installation was built on the Raspberry Pi 3 platform and the Moquette broker. The Internet of things network in this configuration is subject to denial-of-service attacks. The most probable scenarios for a potential attacker are: creation of the large stream of connection and subscription requests, and generation of the large stream of publish messages with a wide variety of recipients. These scenarios are dangerous from the information security point of view and increase the likelihood of the following threats: lack of access to information and message transmission disorder. Traditionally, attacks of this nature are referred to “denial-of-service” attacks. The author has shown that development of protection methods and techniques against this type of attacks when using the Internet of things networks with the MQTT Protocol as the main data transmission channel is the relevant task.

Subject of Research. The paper presents a review of existing detection methods for abnormal activities of web applications. Comparative characteristics are given. Priorities for improving information security tools in web applications are shown. Method. For evaluation of search methods for abnormal activities of web applications, criteria for selecting indicators were defined. Particular attention was paid to such indicators as: the launching speed of web applications after loading, web application responsiveness to user actions and the number of abnormal activities found in comparison with the number of malfunctions found. Three methods of searching for abnormal activities were compared: statistical code scanning, dynamic code scanning and network traffic monitoring. We considered advantages and disadvantages of each method and implementation examples. Main Results. It is shown that the dynamic method of searching for abnormal activities has the best characteristics. The method provides the identification of anomalies associated with traffic transfer and anomalies that occur during the local operation of web applications. The method is implemented as a code analyzer built into the browser engine. The analyzer checks all calls of the web application to the engine and detects abnormal activity based on such calls. In contrast to static scanning, dynamic scanning identifies anomalies in Web Workers, WebAssembly and in the parts of code that are downloaded over the network after the application starts. Practical Relevance. The work can be useful to information security specialists who deal with the problems of protecting web applications, as well as programmers and system administrators at application creation and implementation stage. The results of the work can find practical use in the development of web applications, browsers, and information protection software.

Subject of Research. The paper presents the study of fuzz testing algorithm for “data race” type fault finding in multithreaded software. The algorithm is implemented in the Google TSan tool. The disadvantage of the studied algorithm is the inability to test software products which use non-atomic variables. At this, the use of such tool is excluded for testing of modern applications that implement joint access of program streams to data. We propose a new algorithm for fuzz testing of multithreaded applications and a method for its implementation in the fuzz testing module of the Google TSan tools. Method. Various combinations of the execution of program streams are the input data in the process of fuzz testing of multithreaded applications. The proposed method of fuzz testing for multithreaded software applications assumes that errors in multithreaded applications manifest themselves only at the threads switching points, also called synchronization points. The thread scheduler is implemented as simply as possible. Each thread is assigned with a status marker tracking its activity during the program running. A thread can be in an unknown state (until the first synchronization point), in a state of execution, in a state of waiting in a queue for execution, as well as in a state where the thread has spent its execution quantum but has not reached the synchronization point. Such thread state is automatically changed to the state of waiting at the synchronization point. Thread control is carried out using a separate program thread that monitors the status of all threads and exposes the corresponding marker to the threads that have spent the execution quantum. The error search mechanism is implemented in the software product at the compilation stage by specifying the appropriate options. Main Results. A new fuzz testing module has been integrated in the Google TSan tool, which finds “data race” errors in any multithreaded applications, both with synchronization of access to shared data and with shared access to data. Practical Relevance. Verification of multithreaded software with shared access to data, in particular case of applying non-atomic variables, is especially relevant for the heavily loaded scalable software systems.

Subject of Research. Simulation is one of the most powerful tools among information security provision measures in the design process of communication systems. As compared to other methods, it considers large-capacity communication systems, improves the quality of network resource management solutions and predicts more accurately their consequences. In this case, random graphs are the basic mathematical models for the analyzed systems. They provide fundamental understanding of the analyzed network properties and serve as the basis for simulation. With regard to the processing power high development rate for computers and simulation environments, the study of the topological properties of random graphs becomes especially urgent. It involves analyzing the probabilistic dynamics of centrality measures. Method. In the experiment we used centrality calculation methods for vertices and the graph as a whole based on the scientific apparatus of the graph theory. Comparison method based on span diagrams was used in the study of probabilistic dynamics of graph mathematical models. Main Results. We have studied the dynamics of centrality measures in the Erdös-Renyi random graph model, the Watts-Strogatz small world model and the freely scalable Barabashi-Albert model. The centrality measures of these models have been compared with a real network. We have made it clear that the topological properties of a real network are described by the Barabashi-Albert model to the fullest extent possible. The analysis of centrality measures presented in the paper gives the possibility to trace interconnections between the parameters of various graph models, that, in turn, can be used in the analysis of real networks. Practical Relevance. The obtained results can be applied in modeling of physical and social systems presented in the form of graphs. The paper findings are of interest for professionals involved in the analysis of networks in various fields of science and technology: sociology, medicine, physics and radio engineering.

The paper presents a method of dynamic system roughness research, based on Andronov-Pontryagin concept of roughness (method of topological roughness). Andronov-Pontryagin concept of roughness has been formulated. Reachability conditions of dynamic system required roughness are defined. Concept definition for maximum roughness and minimum non-roughness of dynamic systems is given. Theorems on necessary and sufficient conditions of eachability of maximum roughness and minimum non-roughness and occurrence of bifurcations of dynamic system topological structures are formulated. It is claimed that the sets of rough and non-rough systems are continuous in terms of the set roughness. The condition number of the matrix of bringing to the diagonal (quasi-diagonal) view of the Jacobi matrix at special points of the system phase space is used as an indicator of roughness. The method gives the possibility to control the roughness of control systems based on a theorem formulated using Sylvester’s matrix equation. The basic concepts on synergetics and synergetic systems are presented. The method can be used for studies of roughness and bifurcations of dynamic systems, as well as synergetic systems and chaos of various physical nature. The method is tested on the examples of many synergetic systems: Lorenz and Rössler, Belousov-Zhabotinsky, Chua, “predator-prey”, Henon, and Hopf bifurcation. The main provisions of the topological roughness method are given. The possibilities of the method are illustrated by examples of Belousov-Zhabotinsky and Chua synergetic systems.

The paper presents a neutron thermalization unit, “a source of ultracold neutrons”, designed for basic research in a beam research hull reactor. For new-generation experiments in the fields of weak-interaction physics and astrophysics, statistical accuracy associated with high density of ultracold neutrons is necessary. To achieve high density for helium-4 in the source chamber, which is used as a converter of cold neutrons into the ultracold ones, it should be at the temperature of about 1 K. In case of applying vacuum pumping of helium-4 vapors in ultracold neutron sources, it has not yet succeeded to obtain a temperature below 1.4 K. To achieve lower temperatures, the required saturated vapor pressure should be less than 50 Pa, which is impossible due to hydraulic losses. It is proposed to use a heat exchanger where helium-4 will be cooled by helium-3. The reason is that the temperature of helium-3 is more efficiently maintained by vacuum pumping since its saturated vapor pressure is an order of magnitude higher than that of helium-4. However, between two heliums the temperature drop occurs due to Kapitsa jump and thermal bridge between the helium capsule and heat exchanger. To solve this problem, we proposed optimization using numerical simulation on the basis of a mathematical model of thermal processes in a chamber with superfluid helium. The model takes into account the contact thermal resistance of Khalatnikov acoustic mismatch model with a correction coefficient. An example of such optimization is presented for the ultracold neutron source located in Gatchina. The mathematical model was implemented in the general solver based on the finite element method. A heat exchanger design geometry was proposed with the temperature drop equal to 0.2 K; the temperature of helium-4 was achieved by vacuum pumping of helium-3 vapors at the pressure of 850 Pa. The temperature fall from 1.4 K to 1 K will increase the density of ultracold neutrons by almost an order of magnitude, and increase statistical accuracy of experiments with ultracold neutrons carried out in a non-beam research reactor.

Subject of Research. The paper proposes a method for study of the electronic equipment thermal conditions. The method involves thermal imaging examination of electronic equipment under given external conditions and creation of thermal and mathematical model on its basis. Method. The development of thermal and mathematical models of the object under study was performed through the thermal regime research of the electronics object by a thermal imager. In contrast to the existing approaches, the proposed method provided significant acceleration of the thermal and mathematical model development and more accurate identification of the power of heat dissipation elements. Main Results. We have studied sealed electronic unit thermal conditions cooled by free convection and radiation in the air. The unit is installed in the casing with the air temperature of 50 °C. The heat generating electronic elements on the boards are installed inside the sealed housing. The thermal and mathematical models have been developed to calculate the heat transfer in the electronic unit. The necessary assumptions and their main elements have been determined. The calculation of free convective thermal conductivities and radiant thermal conductivities is performed by the method of successive approximations. According to the proposed method, the element temperature fields of the electronic unit have been measured by thermal imaging. By application of Flir SC620 thermal imager, thermograms have been obtained that determined the average surface temperatures of electronic unit components. The calculated average surface temperatures of the electronic unit elements determined from the thermal and mathematical models are compared with the measured values. Practical Relevance. The proposed method of thermal modeling is applicable for creation of an adequate model of the studied electronic device at various powers and ambient temperatures and for the design and development of various application electronic equipment including the objects located in a closed casing.

Subject of Research. The paper presents a method for calculation of thermal conductivity and viscosity of the gaseous slab laser medium. The method is based on the use of the known properties of its components. Thermal conductivity determination is necessary for mathematical and thermal modeling in the process of thermal mode development. The main feature of the proposed technique is application versatility and the possibility to obtain effective characteristics with sufficient accuracy for complex composition gases containing more than two components. Method. The calculation approach lies in consistent application of the Lindsay-Bromley and Wilke formulas for binary gas to the components of the mixture depending on their molar concentration. The component selection order is due to the smallest variance of the calculated values from the reference data. Main Results. The method was verified by comparison of the calculated and experimental data for three-component mixtures. It was found that viscosity measurement error does not exceed 1.5 % with an average deviation of less than 1 %. The average deviation of the values in the case of thermal conductivity is much higher, but the measurement error does not exceed 5 %. For the most frequently used composition of CO2, N2, Xe, and He mixture as a slab laser medium, the thermal properties were calculated for the minimum and maximum concentrations of carbon monoxide arising during operation. The tables show step-by-step application of the method and the dependence of thermal conductivity on temperature. There is a strong increase in thermal conductivity in the range of operating temperatures (more than twice). For example, at room-temperature range (300 K) it is equal to 0.067 W/(m•K), at 800 K it reaches 0.137 W/(m•K). This difference creates a significant non-uniformity of gas medium temperature field and affects drastically the laser stability. Practical Relevance. The results obtained can find practical application in the development of slab lasers and can be used to eliminate power drops and stabilize the operation of existing lasers providing the regulating process for the component concentrations of the gas composition.  

Subject of Research. The paper presents a review of an effective filament winding method for hollow composite products manufacturing (tubes and containers). Finished products are lightweight, durable and widely used in industry. However, this method has significant drawbacks. The tension of the surface layer and the tension of the inner layers can differ significantly for the formed products. This effect is also observed when the tension of the wound material is regulated. Another significant disadvantage of technology is the change in the cross-sectional diameter of the product in the end zone, where the backward motion of the movable trolley with filaments (tape) is performed. Due to these shortcomings, there are deviations in the winding density and other indicators of the stress-strain state from the planned values. Method. We offer an original method for controlling the radial increment of the composite winding and its density to eliminate mentioned above drawbacks. The method is based on a composite winding model. The model is developed in view of the following representation: the trajectory of the winding-on point is a spiral in a section perpendicular to the axis of the mandrel rotation. The specified winding density, the normalized increment of the winding radius and the change in the angular velocity of the mandrel in the end zones are determined by this model. The model analysis shows that actual speed of the winding point should be equal to the theoretical one for the deterministic winding process. If this condition is met, then all other technological parameters (radius, length, density) will be reproduced on the basis of pre-known functions. It is advisable to maintain the equality between the actual winding radius and theoretical winding radius for the practical implementation of the control algorithm winding process. If this condition is implemented, then the process of material winding will be predictable. Main Results. A control device for the winding process implementing this method is designed. The device provides an action on the winding with variable force, adequately responding to random disturbances and maintaining equality between the actual and calculated winding radii. The Simulink application, an integral part of the Matlab application package, is used for control device modeling. Practical Relevance. The proposed efficient solution for the control composite winding density provides stabilization of the stress-strain state of the cylindrical composite products by changing the radial increment of the winding layers and preventing the effect of the random factors and, consequently, increases production efficiency.

Subject of Research. The paper discusses design principles of educational laboratory bench for practical research of electric drive control systems. The laboratory bench provides training opportunities for students in “Control of Electrical Drives” course and is used to increase the efficiency of material acquisition. Method. The proposed solution was based on the method of mutual loading of electric machines powered by the power converters with a common direct current link. At that, one electric machine can be used as a tested one, and the other as a load one, and vice versa. The flow of power from a machine operating in generator mode to a machine operating in motor mode was ensured, which provides an energy-saving mode of operation when power is consumed only from the network to cover losses in power converters and the machine unit. To study the various structures of control systems for direct and alternating current motors, a method for software creation with a freely configurable structure was proposed. Main Results. The paper describes laboratory stands that contain a two-machine unit, where each electric motor receives power from its power semiconductor converter controlled by a real-time microcontroller control system. The software has been implemented for the synthesis of the control researched structure using the control system settings. The system setting is performed by a number of freely configurable control elements, which are then compiled into a control algorithm for the microcontroller. To ensure the safe execution of the experiment, the control algorithm works in conjunction with the main on-line software. Thus, protection for electric motors and power converters is provided. Thanks to the built-in protection software, it has become possible to achieve reliable operation of electric drives with the power of 1.5 kW, as well as to realize characteristics close to industrial ones. The paper describes in detail the features of laboratory equipment and software for the system of an induction motor field-oriented control. This example demonstrates the setting of control systems, compiling of executable code, an experiment procedure and evaluation of results. Practical Relevance. The considered approaches to the educational equipment creation can be used in the design of similar educational equipment in related disciplines. The results are applicable for scientific and research-pedagogical staff during the course of specialist training in the field of electric drive control systems. The presented equipment has been actively used for more than 5 years and can be of practical value in the educational process.

Subject of Research. The paper considers the issues of neural network application for detection and prediction of road accidents. The overtaking process of cars with crossing into oncoming traffic is analyzed. The potential possibility of road accident reduction while overtaking is shown owing to intellectual assessment of road situation dynamics development. Method. We proposed to use a two-class classifier based on a neural network. Road situations while overtaking with crossing into oncoming traffic were the objects of classification. The data on them was transmitted to the neural network input in the form of the frame set, that is, a graphical representation of discrete states of the “group of vehicles — section of the road” system. Frame formation was expected to be carried out as a result of information exchange between detectors and vehicle-mounted sensors, and road infrastructure, which is developed within the framework of the “smart city” paradigm. Main Results. The road situation is classified as “Dangerous” in case of high vehicle collision probability while overtaking and “Safe”, otherwise. If the situation is considered as “Dangerous”, the vehicle central processor generates an appropriate effect on the vehicle control elements to prevent an accident. Results of situation simulation implemented on Tensor Flow open software library for machine learning are obtained. They showed high prediction accuracy (0.96) on artificial data set. Practical Relevance. The results of the work can be used in promising unmanned and manned vehicles having radio communication with road infrastructure elements within the “smart city” concept to prevent road accidents caused by dangerous overtaking.