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Nowadays, machine learning (ML), especially deep learning(DL) methods, provide ever more real-life solutions. However, the lack of training data is often a crucial issue for these learning algorithms, the performance accuracy of which relies on the amount and the quality of the available data. This is particularly true when applying ML/DL based methods for specific areas e.g. material characteristics identification, as it requires huge cost of time and manual power getting observational data from real life. In the mean while, simulations on HPC have already been commonly used in computational science due to the fact that it has the ability of generating sufficient and noise free data, which can be used for training the ML/DL based models. However, in order to achieve accurate simulation results the input parameters usually have to be determined and validated by a large number of tests. Furthermore, the evaluation and validation of such input parameters for the simulation often require a deep understanding of the domain specific knowledge, software and programming skills, which can in turn be solved by ML/DL based methods. In this paper, a novel hybrid workflow combining a multi-task neural network and the simulation on high performance computers(HPC) is proposed, which can address the problem of data sparsity and reduce the demand for expertise, resources, and time in determining the validated parameters for simulation. This work is demonstrated through experiments on determination of material behaviors, and the results prove a promising performance (MSE = 0.0386) through this workflow.

In this study, laboratory preparation of the biosensor based on silicon nanowire field-effect transistors (SiNW-FETs) for virus indication was performed. The authors examined a number of decontamination agents for cleaning the surface of SiNW-FETs using solutions such as hydrogen peroxide, sulfuric acid, hydrofluoric acid, ammonium hydroxide. Biosensor surface functionalization for virus indication was performed through the attachment of antibodies by covalent binding using (3-aminopropyl) triethoxysilane and glutaraldehyde as solutions of cross-linkers. It was determined that a mixture of hydrogen peroxide and water is effective for removing contamination, and (3-aminopropyl) triethoxysilane in ethanol is effective for surface modification.

Study review is given for mathematical models dedicated to induction motor non-symmetrical modes research. Papers are reviewed, featuring mathematical models based on magnetic-coupled electrical circuits theory, magnetic circuits theory, symmetrical components method. The article works out the possibility of studying various complexity non-symmetrical modes of induction machine. The conclusions and the summaries describing differences and peculiarities of these approaches are also formulated.

A mathematical model, proposed by the authors to study the processes of nonlinear heat transfer during electron-beam deposition with direct feeding of filler material into the heating source influence zone, is described. The model is implemented in the form of a computer program based on numerical methods for solving the energy equation with moving boundary conditions. An algorithm is described that makes it possible to take into account the latent heat of melting when calculating the temperature field. Using this descriptive model and a discrete model of PID-controller, a quasi-normative model has been developed that allows analyzing closed-loop control processes to stabilize the deposited layer temperature. The fundamental possibility of using PI- and PID-controllers for heating source power controlling in multilayer deposition process of a straight wall made of AISI 316L steel is shown, as well as the need to turn off feedback when passing from one layer to another.

The paper describes new experiments on cooling of metallic spherical and cylindrical bodies in film boiling with submerged impinging jet of the same liquid. The submerged jet impingement is considered as a method of destabilization of the vapor film around a cooled body during film boiling due to initiating a cold spot at the stagnation point. From this cold spot, the cooling front can propagate along the cooled surface with transition to the more intensive heat transfer regime. According to the results of the experiments, the jet leads to significant disturbance of cooling uniformity with an increase in surface temperature at vapor film collapse (transition temperature).

A question answering (QA) system based on natural language processing and deep learning gets more attention from AI communities. Many companies and organizations are interested in developing automated question answering systems which are being researched widely. Recently, the new model named Bidirectional Encoder Representation from Transformer (BERT) was proposed to solve the restrictions of NLP tasks. BERT achieved the best results in almost tasks that include QA tasks. In this work, we tried applying the multilingual BERT models (multilingual BERT [1], DeepPavlov multilingual BERT, multilingual BERT fine-tuned on XQuAD) and the language-specific BERT model for Vietnamese (PhoBERT). The obtained result has shown that the monolingual model outperforms the multilingual models. We also recommend multilingual BERT fine-tuned on XQuAD model as an option to build a Vietnamese QA system if the system is built from a multilingual BERT based model.

The paper discusses one of the promising areas of digitalization of production - the introduction of industrial robots and robotic systems. A solution to the problem of controlling the movement of a processing Robot Manipulator (RM) along a programmed trajectory is proposed. To control the RM, a digital double is used, which allows, on the basis of the dynamic model and the measurement information received from each link of the RM with some accuracy, to generate a control signal to the electric drive of a real RM operating under conditions of disturbances and incompleteness of information. The determination of the parameters of the digital twin model is carried out in real time using identification methods. The specified positioning accuracy is achieved through the use of an algorithm using a predictive model that allows, on the basis of the forecast, requirements for positioning accuracy and the shape of the control signal, to adaptively adjust the regulator parameters. To conFigure the parameters, a criterion is used that ensures accurate positioning of the links of the RM with a minimum number of oscillations of the control signal. This approach allows to reduce the load on the electric motors and the control unit when the RM moves along the program trajectory.

Different versions of quantum cutting mechanisms in Yb doped Scheelite-like molybdate and tungstate single crystals were studied, with participation of various schemes of donor-acceptor interaction (various kinds of donor centres: self-trapped excitons at molybdate/tungstate complexes; high-lying excited states of Yb3+ ion; Yb2+ ion; traps based on cation and oxygen vacancies; accidental impurities.). All the versions were rejected.

The possibility of controlling the spectrum of the generated third harmonic for high quality-factor resonant metasurfaces is examined. The ultrafast dynamics for both fundamental wavelength and third harmonic generation is observed in all-dielectric metasurfaces with pump-probe technique.

The technique is proposed for creating a matrix of control signals with elements of phased antenna array of Ka-band with discrete semiconductor and analog ferrite phase shifters. During its creation, parameters of phase shifters are not identical and are taken into account in the process of their manufacture, as well as under external conditions, including temperatureDielectric properties of used materials are also taken into account when using radio transparent shelters or fairingsThe results of experimental studies using the proposed technique are given by the example of 9-element linear phased antenna array. It is shown that proposed technique of creating a matrix of control signals allows one to exclude the effect of lack of identicalness of phase characteristics of all its elements in the channels on the parameters of radiation patternIn addition, scanning process eliminates the need to use computing devices. All necessary information is stored in the memory of the control unit.

We propose several heuristic methods for finding an approximate solution to the following inherently combinatorial problem: Given N points in ℝn, construct the minimum- size ellipsoid covering exactly N − k of them, where k ≪ N. Various assumptions on the nature of the points and their amount are considered; the results of numerical experiments with the algorithms are discussed.

This paper studies passive relative motion of two spacecraft (SC) in one orbital plane taking into account the second zonal harmonic J 2 of the Earth gravitational field. Inspector spacecraft moves in the area of the inspection ellipse, in the center of which the target spacecraft is placed. Inspection motion for different orbits is analyzed. Method for selecting the initial conditions of both spacecraft motion that ensure the permissible variation of the inspector SC relative trajectory from nominal one at the given time interval is proposed. Results of the numerical study support the computed stability conditions, which make it possible to reduce the fuel costs for inspection motion.

A citizen’s quality of life is always tightly related to the improvement of general technological progress in many subject areas – from mechanical and electrical engineering, information technology, mining and technological fields of industry up to biotechnological processes of cellular and molecular dynamics, medicine, and biomechanics of living organisms. It also depends on an achieved level in theory and mathematical description of the internal dynamic processes of different physical nature, simulation of these processes and further practical implementation of the theory into the real technical objects. An important role here plays computing resources which allow to minimize computational time and to increase the complexity of the simulation models. Parallel computing systems open for scientists a new level of simulation, but they also set high requirements on specific knowledge and experience of the users. As a result, granting access to computing resources is not sufficient, specialised training of the personnel is also needed. The same problem appears during the integration of a computing centre into the university educational program – new courses, workshops and learning materials are required. In this paper, we share our experience and a vision, how modern computing resources could be integrated into university life, what challenges and issues can be expected here. Also, we present a new scientific project between Ukrainian and German academia partners which has a goal to enhance accessibility, usability and improve the system organization of parallel computing resources. The project represents a multidisciplinary research area of Parallel Simulation Technology (ParSimTech) and focuses on the creation of the Ukrainian research and training ParSimTech centre.

The paper considers a class of digital nonlinear filters defined by a discrete truncated Volterra series. Such filters called Volterra filters or polynomial filters are a natural generalization of linear filters. The computational weight of polynomial filters is widely known to exponentially grow with the nonlinearity degree. This article is devoted to design of effective algorithms of polynomial filtering based on the algebraic theory of signals and systems. The implementation of nonlinear filters of this class is based on the procedure of data segmentation and calculation of nonlinear circular convolutions. In the paper we suggest recursive algorithms for calculating nonlinear circular convolutions based on multivariate polynomial transforms and the Chinese remainder theorem. Unlike the discrete Fourier transform, the calculation of polynomial transforms does not require multiplications and is implemented using additions and shifts. It is shown that the calculation of a nonlinear circular convolution of the m- th order can be reduced to the calculation of the convolution of the (m- 1)- th order, the execution of the operation of transition to a single variable in the polynomial region followed by restoring the result using the Chinese remainder theorem. A modification of the recursive algorithm for calculating nonlinear circular convolutions using fast polynomial transform algorithms is proposed. This algorithm allows to reduce the computational costs by using an effective procedure based on the recursive addition of polynomials with exponentially growing bases for the multiplication of polynomials. The article concludes with the assessment of computational complexity of the proposed recursive algorithm and the recommendations for its application.

Dielectric electrically small antennae are attracting high interest due to their promising applications both in optical and microwave bands. Efficiency of such antennas is usually bounded by low directivity. The stochastic optimization procedure is used to demonstrate superdirective designs of small all-dielectric antennas being spherical multilayer structure. The procedure is based on an efficient and accurate rigorous electromagnetic model which allows for performing large scale optimization on personal computers with limited resources. For optimization we compared different stochastic algorithms, and the JADE demonstrated the best performance. The found designs possess the directivity that go beyond the conventional theoretical bounds for antennas smaller than the wavelength and outperform previously attained results.

This paper deals with stator current control in scalar control system of frequency controlled induction motor drives and describes mathematical model of induction motor's stator current unit taking into account induction motor's electromagnetic transient responses. Several stator current controller's with signal adaptation structures have been tested, such as based on both constant and variable parameters PID-controller. Also an approach to controller's parameters synthesis is described. For the proposed control system's properties estimation the following time-domain criteria were selected: transient response time, overshoot, maximum reaching time. Reactions for both reference and disturbing influences have been tested. It is shown that application of PID-controller with variable parameters and signal adaptation provides high performance combined with robustness toward disturbances, as which internal electromotive force inducted in rotor circuit are taken into account. Rational field of use for proposed current controller with signal adaptation are scalar control system with enhanced electromagnetic torque forming ability.