This publication opens a series of review papers devoted to the current design problems of the next generation unmanned airplanes that are expected to appear in the period from 2025 to 2035. The series of papers considers airplanes with vertical take-off and landing, air launch of small satellites into the orbit, cargo transportation tasks, issues related to new aerodynamic forms, as well as hybrid, combined and distributed power units. The first paper of the cycle is devoted to the conceptual aerodynamic design of the airplanes with a short take-off and landing, and with technical and economic characteristics on cruise flight conditions no worse than for traditional airplane based on aerodrome with long airstrip. We consider traditional linear methods for aerodynamic scheme analysis and weight analysis, as well. The main relationships and references to the works enabling the parametric analysis of the aerodynamic configuration are given. It is concluded that one of the most promising areas in the field of airplanes with a short take-off and landing is the development of aerodynamic circuits constructed as a "flying wing" of small aspect ratio and large structural height.

The paper considers the features of synthesized holograms suitable for practical use. It is established that binary holograms are the first of all suitable ones for successful application in practice. In order to select the most suitable (optimal) level of hologram binarization, we propose a criterion for estimating the quality of an image reconstructed with a binary hologram. An algorithm is developed to find the optimal level. On the basis of the conducted experiments it is established that the introduction of the developed module gives the possibility to reduce the search time of the optimal binarization level of the hologram by eleven times in comparison with manual search.

Subject of Research.The paper presents the study of inscription process distinctive features for superimposed fiber Bragg gratings. We analyzed spectral characteristics changes of superposition segregated gratings that appear during inscription of subsequent diffraction structures over the first ones. Method. Superimposed fiber Bragg gratings inscription was carried out by means of Talbot interferometer. Excimer laser system Optosystems MOPA CL-7550 was used as a radiation source. It was operating on gas mixture KrF (radiation wavelength is equal to 248 nm). The phase mask with a 1000 nm period was implemented in the inscription scheme for laser beam amplitude separation. Fiber Bragg gratings were inscribed in anisotropic optical fiber with 12 mol.% of GeO2 in optical fiber core. Main Results. Samples of superimposed fiber Bragg gratings were obtained and their spectral characteristics were analyzed. We have studied the regularities of the change in the reflection coefficient and the central wavelength of the first grating of the superposition from the number of diffraction structures inscribed over it, the exposure time during the inscription, and the spectral interval between them. Based on the results obtained, recommendations are given for optimizing the superimposed fiber Bragg gratings inscription process. Practical Relevance. The obtained superimposed fiber Bragg gratings can be used in the manufacture of optical filters, sensors for simultaneous measurement of several parameters, as well as for multiplexing and demultiplexing signals in telecommunications.

 The paper presents the application of speckle correlometry method with the spatial ring filtration of back scattered field with the usage of localized radiation source for the study of dynamic thermally activated processes in gel-like structures containing submicron particles and nanoparticles. Speckle-modulated images contain information about the processes taking place inside the investigated medium; therefore, they are effectively used in biomedicine and materials science. The transformation process from lysol to gel was considered in media based on technical gelatin dissolved in water with weight fraction equal to 0.28% containing titanium dioxide nanoparticles TiO2 (volume fraction of particles is equal to 0.1% and 0.01%) and media based on food gelatin dissolved in water with weight fraction equal to 0.3% containing titanium dioxide nanoparticles TiO2 (volume fraction of particles is equal to 0.01% and 0.01%). The temperature of the medium during the structural transformation of "sol-gel" system was changed from 50 to 25°C. To estimate the experimentally obtained distribution of space-time intensity fluctuations of backscattered speckle fields, the correlation analysis and the formalism of Kolmogorov structure functions were used. The estimations of activation temperatures for the “sol-gel” transition process for technical and food gelatin were obtained. This approach can be successfully applied for the study of dynamic systems, for example, the demonstration of Brownian particle movements.

This paper is devoted to tuning of the finite-time control algorithm in order to reduce the transient process time of a closed-loop system. The control object is a chain of consecutively connected integrators with a state vector available for measurement. It is assumed that the control object operates under conditions of deterministic external disturbances and parametric uncertainties of the system. The advantage of the modifiable algorithm in comparison with previously presented results is the absence of the need for additional computational procedures. However, a lower convergence rate of the system trajectories to the equilibrium position can be noticed as a drawback. The presented tuning of the finite control law makes it possible to reduce the time of the transient process of a closed system. The tuned finite-time control algorithm is developed by combination of the method of implicitly defined Lyapunov function with the theory of weighted homogeneous systems. Analytic expressions are obtained that give the possibility to estimate the convergence time of the state vector to the equilibrium position, as well as the possibility of its decrease at the proposed approach application. Computer simulation of the developed control algorithm was performed on the triple-integrator system with deterministic external disturbances in control channel. It has confirmed the effectiveness of the presented theoretical results.

The paper considers robustness problems of a class of weighted homogeneous systems with negative homogeneity degree in relation to the delay. It is shown that in the case of global asymptotic stability of a nonlinear weighted homogeneous system with negative homogeneity degree, in the presence of a delay in the system, all the trajectories converge asymptotically to some compact set containing the origin. In the absence of delay, such systems reach their equilibrium position in a finite time. The robustness analysis also covers cases of variable and multiple delays. The presented analysis is based on the application of the Lyapunov methods for delayed systems (the Lyapunov-Razumikhin function method) and the theory of weighted homogeneous systems. Computer simulation was performed to verify the analysis of system robustness with a negative degree of homogeneity in relation to the delay. A stabilizing system that represents a double integrator is used as an example. This system is weighted homogeneous with a negative degree when using a nonlinear state feedback control law that ensures that the system achieves its equilibrium position for the desired finite time. During computer simulation, the state vector was available for measurement with some delays. The computer simulation has confirmed the effectiveness of the presented theoretical results.   

Subject of Research. Dendrimers are polymer molecules that regularly branch from a single center. Dendrimers can be used as antibacterial, antiviral and anti-amyloid agents. Recently, it has been shown experimentally that some dendrimers can prevent the formation of amyloid fibrils and destroy already existing fibrils consisting of stacks of amyloid peptides. Two systems containing lysine dendrimers of the second or third generation and a stack of 16 amyloid peptides in aqueous solution were studied in the present paper. Method. The study was carried out by computer simulation with the use of the molecular dynamics method. Main Results. It was shown that lysine dendrimers of the second or third generations destroy amyloid stack and form stable complex with peptides. Both kinetics of the amyloid stack destruction and formation of complexes with dendrimers, and the equilibrium structures of the complexes formed were studied. In particular, it was shown that electrostatic interactions between charged groups of dendrimers and peptides play the main role in the destruction of stacks. In the complexes obtained, the peptides are located mainly on the surface of the dendrimer and only slightly penetrate into the complex. Practical Relevance. The data obtained can be used in the future in the treatment of Alzheimer's disease, since it is believed that one of the reasons for its occurrence is the formation of oligomers and fibrils consisting of stacks of amyloid peptides.

We propose a method of rotor imbalance correction for electrostatic gyroscope. The method is based on redistribution of the material on the beryllium rotor surface during deposition of the titanium nitride coating by cathodic arc physical vapor deposition (Arc-PVD) technique. The deposition process is carried out using one arc source made of BT-1-00 material, located in the horizontal plane of the vacuum chamber of "Bulat-6" installation at nitrogen pressure of 1.2ˑ10-3 Pa. Size distortion of the rotor  caused by thermal expansion during heating to 300 °C, is not more than one hundredth of a micrometer because of the high dimensional stability of beryllium. The  titanium nitride coating with a thickness about 1 μm is formed during 30 min deposition on the spherical surface of the rotor with a diameter of 10 mm. The imbalance correction is achieved by deposition of the coating with the center of the coating sphere displaced relative to the geometrical center of the rotor in the direction opposite to the direction of the rotor imbalance vector. The required displacement is determined by the rotor kinematics during the deposition process and is provided by the developed device with three degrees of freedom: two rotational ones – constant and cyclic around two different axes of the rotor, and reciprocating displacement of the rotor relative to the source of the sputtered material along the flow axis of this material. The developed device provides fastening of the rotor in four- needle clamp. The calculation of rotor fixation scheme in this clamp is carried out, ensuring the positioning needles outside the area of the raster pattern formed in the rotor equatorial zone during the next laser marking operation. The experimental data showed that it is possible to produce real rotors with the imbalance correction accuracy within two decimal places of a micrometer.

Classical methods of error detection are not efficient when an attacker controls the process of error injection. Nowadays the problem of providing high level of security for cryptographic systems, secret sharing schemes, flash memories and other communications, computation and storage systems is central to information security. To solve this problem the algebraic manipulation detection (AMD) codes have been proposed by Cramer at EUROCRYPT 2008. AMD codes represent a new class of nonlinear error detection codes which minimize the maximum of error masking probability. The paper presents the findings on behavior research of perfect nonlinear functions used in algebraic manipulation codes when the input distribution is not uniform. This research gives the detail review of behavior of perfect nonlinear functions and the maximum of error masking probability in case of different irreducible polynomials used for AMD codes. The received measurements can be used for selection of coding function that can be the most suitable for encoding information in specific situation such as given distribution of input codewords, irreducible polynomial and other parameters. The paper highlights the cases of parameter changing in coding system which do not change the error masking probability distribution or the changes are insignificant. These cases can be used to modify designs without reducing the stability of the entire integrity system to algebraic attacks that gives the possibility to customize the system for practical needs. Such parameters as the distribution of input codewords are also considered. They have an adverse effect on the stability of the system to algebraic manipulations. Changes in the input codeword distribution should be monitored in the integrity system, and additional transformations for input codewords should be used for security reasons or the encoding function within the integrity system should be changed.

The composite architecture of the multi-agent bionic search system is proposed to solve the general distribution problem based on swarm intelligence and genetic evolution. Three approaches to the construction of such architecture are considered. The connecting link of this approach is a unified data structure that describes the solution of the problem in the form of a chromosome. The new principles and methods of coding and decoding of chromosomes for the representation of the general distribution problem considered in this paper exclude incorrect solutions, are distinguished by simplicity and linear estimates of temporal and spatial complexity. A modified paradigm of the particle swarm method is proposed. To organize the swarm movement of particles in hyperspace of solutions, a directed mutation operator has been developed. Experiments have shown that the quality of the solutions in the hybrid algorithm is 10 to 15% better than the genetic and swarm algorithms. The overall estimate of time complexity for any hybridization approach does not exceed the estimate of the time complexity of the genetic algorithm and lies within the range О(n2)–О(n3).

The paper presents a new method of the object shape restoration based on the tomography approach in signal processing. Most existing methods of solving the problem require either an active surveillance system that besides images registration includes special illuminating of the object, or it is necessary to identify corresponding points in the case of stereo images, sometimes also with illuminating. The proposed method requires neither of that. Instead, it is enough to allocate the area of the object image on each image plane. It is also necessary to know the image planes positions. The method essence is the following. We assume that the observed space area that includes the object is known. We divide it into a set of small volumes, resolution elements (ReE), and number them. The observed space area is described by the vector-original with the amount of components equal to the amount of ReE and the values of components equal to 1 if the ReE with the same number is inside the object and equal to 0, if  it is not inside it. Obviously, if we know such a vector, it is quite simple to receive a three-dimensional object, forming it from ReE with numbers equal to the numbers of the vector-original elements equal to one. Thus, the main stage of solving the problem is the restoration of the vector-original by its mapping. The problem is solved with the aid of   logic algebra. The mapping is being formed from binary images. The logical expressions have been obtained that give the possibility to reconstruct the vector-original; computing simulation of the method realization has been performed, and as a result the object shape has been obtained as the set of ReE inside it, that makes it possible to consider the restored object in all angles.

Subject of Research. Simulation is the main way for testing technologies in the field of multi-hop wireless networks. Creating a simulation model of multi-hop wireless network is a time-consuming task associated with the use of specialized software tools, called network simulators. This paper presents the modern modeling experience of multi-hop wireless networks and focuses on the main problems. One of the main problems is the impossibility to analyze comparatively the experiment results conducted by various researchers. The reasons for this fact are associated with the models used for testing, imitation experiment planning and the principal differences in the network simulators(heterogeneity of the modeling environment). Method. In this regard, a technology is proposed allowing for simulating experiments with models of various multi-hop wireless networks and using various network simulators in an automated mode.Main Results.Within the framework of this technology, we have developed a generalized conceptual model of multi-hop wireless networks and a specialized software package that automates the execution of experiment series in a heterogeneous modeling environment. Practical Relevance. The software package gives the possibility to use the other researchers' results by reconstruction of simulation experiments most closely approximate the ones carried out by these researchers. The efficiency of software package application is confirmed by a decrease in time costs and the results of conducted experiments.

Subject of Research. The paper deals with a new design solution for the odor recognition system aimed at detecting threats. An algorithm for neural network training that solves the problem of recognizing dangerous substances by odor is developed. We present experiment results on the selection of neural network hyper parameters, its architecture and testing. Methods. The detection system is a comprehensive solution that gives the possibility to ensure the safety of life and human activity applying odor detection of threats. The solution complexity is realized by technology platform choice of the Internet of things and the neural network that solves recognition problem. Main Results. We propose a new approach to creation of odor system for detecting threats that makes it possible to improve technologies for ensuring the safety of life and people's activities. The working capacity of the proposed solution is demonstrated on the layout. It shows the possibility to use the technology of the Internet of things at the system implementation stage and to deploy their work on any territory, including hard-to-reach areas. The convergence of the results of the trained neural network with test sets of concentrations of hazardous substances in the air is shown. Practical Relevance. The odor system for threats detection can be useful as an element of an integrated solution to ensure the safety of people on any territory, depending on the tasks assigned. The odor detection system for dangerous substances has been brought to the layout, which makes it possible to detect such threats as the leakage of benzene, butane, methane, propane and the ignition at an early stage.

Subject of Research.Evolutionary algorithms use various mutation operations, which can be optimal at different stages of optimization. We formulate the task of choosing the most suitable mutation operator while optimizing. We propose a method for adaptive selection of mutation operators with probability depending on the current fitness. This property makes this method efficient on every stage of optimization. Method. We use two classes of algorithms: artificial immune systems, which are efficient at the initial stage of optimization, and randomized local search, which is efficient towards the end. The new method and the existing algorithms are compared experimentally on two benchmark problems. Main Results. The method for adaptive selection between artificial immune systems and local search mutation operators is developed. An experimental comparison of the proposed method with existing ones was performed. It showed that the proposed method is efficient under various computational budgets and finds optimal problem solutions faster than the other methods. Practical Relevance. The proposed modification improves the performance of algorithms when solving dynamic optimization problems with fitness functions changing in time, such as Pickup-and-Delivery Problem.

Subject of Research. Static and dynamic problems of coupled electroelasticity are considered for electrostatic (capacitive) transducers used in sensors and actuators based on nano- and microsystem technology of various applications. Method. Above-mentioned problems are analyzed by mathematical apparatus of nonlinear mechanics and bifurcation theory as well as modern numerical methods, including numerical continuation techniques for nonlinear boundary-value problems of mathematical physics. Main Results. Comparative analysis of analytical and numerical methods was performed for nonlinear static and dynamic boundary-value problems of electroelasticity for microsystems and nanosystems engineering. Basic discrete (nonlinear nano/micro-electromechanical oscillators) and distributed (membranes, plates) electromechanical models were considered. Equilibrium forms, their stability and bifurcations were studied for afore-named elastic systems under the influence of electric fields of various configurations. Bifurcation diagrams were derived depending on key physical parameters. Nonlinear dynamic problems for elastic systems at time-varying electric fields were also considered. Practical Relevance. The present research is of considerable practical significance because it reveals and analyzes qualitatively the elastic elements properties and characteristics that are important for nano/micro-system design, such as equilibria structure and stability, amplitude and force response of the system, etc. Used methods and mathematical formulations can be applied in the design process of micromechanical accelerometers and gyroscopes, pressure sensors, micro-pumps, capacitive micro-machined ultrasound transducers, radio-frequency and optical switches, electromagnetic energy harvesting systems and biomedical devices.

The paper presents a version of technical implementation of automated installation and its performance algorithms for determining the piezoactuator parameters. The evaluation was carried out by a linear regression form of transfer function. The first approximations were used as the derivatives. The known parameters of the piezoactuator were used to analyze identification procedure results and determine the object parameters. A stepwise action was applied to the input in the first method. In this case, it is necessary to perform measurements with a frequency more than 200 kHz to ensure an error less than 1%. The paper deals with the problems related to making measurements in real time mode and to processing large amounts of data. The feature of the piezoactuator operation was used to improve the quality of the procedure – its ability to direct acceleration measurement. Also, a pulse width modulated signal with a variable duty cycle was formed to obtain a more informative output signal. The conclusion was drawn that the application of the least-squares method in conjunction with the pulse-width input action and the usage of the accelerometer makes it possible to obtain results with a small error in the estimation even when operating at sampling frequencies near 20 kHz. The embedded System Identification Toolbox enables accurate determination of a model on 20 kHz frequency, technically realizable in real time mode. As a result, the variant of technical implementation of automated installation and performance algorithms were proposed. The parameters convergence was provided with an accuracy of 0.5% at measurement frequency of 20 kHz that allows for real-time operation in MATLAB Simulink Desktop Real-Time software.

The paper deals with the tasks of increasing manufacturing flexibility of automated production lines on the example of microlens assembly automation. Consideration was given to peculiarities of building an automated microlens assembly line and to specifications of the basic microlens design. Weight and dimensional parameters of the basic microlens main units were analyzed and systematized. It was noted that the range of items produced by the automated line and its manufacturing flexibility are substantially influenced by the design of universal arm grippers interoperating with microlens parts and assemblies in the process of automated assembly that gives the possibility to cover an entire range of microlenses. Designs of known industrial grippers were reviewed and an analysis was provided as to the possibility of their application for the automated microlens assembly line. The analysis resulted in two alternative schemes proposed for building a universal gripper. A developed and proved out methodology of qualitative-quantitative assessment of technical solutions was used. This methodology is intended for mechanical system developers, who make a justified choice of technical solutions from a variety of alternatives, and is aimed to raise the quality level of technical products being designed that are introduced at the design stages. Following the presented methodology, the qualitative-quantitative assessment of two proposed gripper variants was carried out, and the third universal gripper construction variant was put forward based on its analysis. Specific universal gripper design for an automated microlens assembly line was proposed.

The paper presents a novel method of the reliability increase for safety system (overspeed protection system) for the high-speed steam turbine. Reliability increase is achieved by use of the intelligent mechatronic module with overrunning clutch, and the increase of the number of mechanical overspeed trip mechanism inspections compared with the present regulation. The proposed design allows for safety system testing by the rotation frequency increase of normally running equipment that is radically different from prototypes. This solution application gives the possibility to abandon the existing practice of acceleration to the maximum permissible turbine rotation frequency that ultimately increases its lifetime. In contrast to its prototypes, the test can be carried out automatically without operator intervention. It gives the possibility for application of visual spectroscopy method as a complementary tool to detect a defect, affecting the performance of the proposed system, even on a running turbine. There are no currently existing prototypes of such system that can identify defects before the mechanical security system is tested. The proposed technical solution can serve as a good alternative to costly electronic security systems in the current economic climate. At the same time, the problem of achieving the necessary reliability of the turbine will be solved.

The paper presents a novel method for wagon counting of moving trains. The method is based on optical coherent reflectometry data from an area of train track laying. A wagon number operational control in a train composition is widely used as one of the main methods of train integrity monitoring. In turn, train integrity is one of the main important factors in the security provision of railway traffic. The method proposed in the paper is simple, intuitive and easily realizable in practice. Its high economic efficiency is caused by the fact that the method does not require any additional equipment with exception of that already installed in the monitoring system of the train movement regulation on the base of optical coherent reflectometry. The proposed algorithm is built upon the joint application of the hidden Markov model and Viterbi-like method used for sequence of states evaluation of the hidden Markov model. The field-service tests performed at the real railroad haul have proved high practical efficiency of the approach.

The paper provides a brief review on structural and technological features of Lower Limb Exoskeletons that have been manufactured until recently and the description of their disadvantages.  Exoskeleton is a device designed to compensate for the lost functions of a human operator by increasing muscle strength and expanding movement amplitude with its outer frame and driving parts. Lower Limb Exoskeletons are developed to support people who have partially or completely lost lower limbs dynamics. The research and development background dates back to 1960s. Over the years, great progress has been made by scientists and researchers from all around the world. However, despite various strategies and attempts to achieve perfection in operating an exoskeleton in the current state of science and technology, it is still a challenge to develop an auxiliary model that endows with both super-efficiency and naturalness. Consequently, the paper intends to highlight the problems to be resolved and the future trends in this field. Exoskeletons have been limited in their availability for wider application by general population because of their high cost. Moreover, technological and structural issues related to design, safety, framework deterioration and optimization remain open-ended. As a technological breakthrough is an evolving process, this review can assist in conducting current research and making recommendations for perspective developments in the field of Lower Limb Exoskeletons.

The paper presents the experimental approaches to mathematical model creation for the lower limb movement of a human's locomotor system. The experimental research data based on analysis of four persons manner  of walking has been used as initial conditions. The data has been obtained in the kinesiology and biomechanics laboratory of Tartu University, Estonia. The model has been constructed with the use of the measurement data of hip and knee flexion kinematic parameters. The frequency ratio of oscillatory  movements during the hip and knee flexion has been established.. The research has been performed on the "toe-to-ground contact" phase kinematics that gave the possibility to discover the constancy parameter being of great concern for the model of system with one degree of freedom (in the jump-off phase backed on the forefoot) and with two degrees of freedom (in transfer phase). We took into account elastic and viscoelastic model parameters in the calculation.

The paper presents experimentally obtained dependences of optical losses and h-parameter of the birefringent optical fiber with tin coating on a winding diameter. The optical losses were measured by insertion loss method, and h-parameter was measured by orthogonal polarizer method. The winding diameter varied from 5 mm to 35 mm. A minimal acceptable winding diameter of 30 mm was determined for this fiber used as a reference arm in interferometric sensor wherein optical losses are equal to 0.07 dB/m, and h-parameter is equal to 50×10-4.

We propose organization schemes for project and production procedures in industrial companies when performing full-scale experiments on instrument-making products. The paper also presents control flow chart for correction of design, program and technological documentation in the product life cycle. We define the procedures which digitalization allows for the automation of development and subsequent documentation support. This process is aimed at transition of the industrial companies to functioning under the conditions of the digital economy according to the Industry 4.0 production standard. The study shows that implementation effect for the most advanced industrial technologies can be achieved by applying the Internet of Things and the imitation modeling technologies using the product digital models as a component of the engineering workstation. The work results can be used to develop the automation design algorithms for instrument-making (machine-building) digital production that is functioning in the digital economy conditions of the Industry 4.0 production standard.