The present paper is devoted to the study of the structural degradation mechanisms of ferroelectric having Pb_1−хBaхZr_0,53Ti_0,47O_3−δ composition. On the base of investigations of the influence of temperature-time synthesis modes on the structural perfection degree of the Pb_0,85Ba_0,25Zr_0,53Ti_0,47O₃₋₈ compound, it has been determined, that a shift of the position of the XRD reflex from the plane (112) and its broadening, which is caused by the amorphization and an increase of the elastic stresses in the material crystal lattice during the annealing of the compound. It has been demonstrated that at the increase of the annealing temperature up to 520 K, the crystal lattice of the ferroelectric is deformed by means of a formation of VPb,V0 and [V О •• 2Pb / i ] defects, which is realized in a decrease of the I(hkl) intensity relationship of the XRD reflexes from the planes (112) and (211). It has been supposed that an excess of lead is produced on the grain boundaries as a result of this annealing process, which promotes a local manifestation of the liquid phase. This phase which takes place in the transfer of the material components, not only increases the interaction of the reacting components, but lowers the stability of their crystal lattices due to the formation of point defects, as well. In this case, the lattice state is determined both by the emergence of the oxygen (VО) and lead (VPb) vacancies, as well as of the associates of the [V О •• 2Pb / i ] type, and by the emergence of various elastic stresses, which promotes the relaxation of the chemical bonds between atoms, caused by the deficiency introduced into the anionic sublattice of the Pb_0,85Ba_0,25Zr_0,53Ti_0,47O₃₋₈ solid solution at the oxygen desorption process.

The purpose of this article is to analyze methods, approaches, and tools of distributed ledger technology (DLT) for working with documents in education. The objectives of the article are to analyze problems with the authentication of educational documents, develop new structural solutions using block chain technology, consider two models, and evaluate their use for educational documents.

Authentication of educational documents is carried out using state registers, which is a complex and resource-intensive process. There is an increase in the number of forged documents in the world, which calls into question the effectiveness of modern mechanisms. Distributed ledger technology (block chain) is a sustainable technological trend that affects the development and quality of the digital economy. The existence of a mechanism for verifying the authenticity of educational documents that is resistant to malicious manipulation is an urgent task that goes beyond the sphere of education, possible solutions to which are proposed to be considered in this paper.

The article provides a brief description of DLT and considers the approach of using the technology to authenticate educational documents. It consists of two main stages: the issue of a digital educational document and its verification. The role of a trusted third party in the issue and validation process is considered. The paper presents the models for issuing and validating digital documents based on distributed ledger technology, which allows one to eliminate the limitations and shortcomings of existing approaches. The effectiveness of the approach based on the proposed models is revealed. The formulated approaches can be applied in various socio-economic areas and public administration to work with similar documents.

Currently, radio monitoring systems are being actively improved in the direction of expanding the range of operating frequencies and the width of the spectrum of processed signals, which in some cases requires changing approaches to the design of their receiving devices. The purpose of the article is to substantiate the methods and circuit design options for implementing a receiver of an ultra-wide-range radio monitoring system and to justify the sequence of selecting the element base and calculating the parameters of the receiving path. The research proves expedient to choose the infradine structure of the radio receiving path as a basis, in which the frequency of the mirror channel is located far from the frequency of the main channel, so the mirror channel is easily suppressed by a simple low-pass filter. One of the main problems that arise when designing ultra-wideband radio receivers is the simultaneous provision of a large dynamic range and a low noise figure. To reduce the noise figure, a variant of constructing a path was proposed, starting with a low-noise amplifier with increased parameters of nonlinear selectivity, which is acceptable if there is a low probability of intermodulation combinations. The article suggests a receiver with an operating frequency range of 0.5–18 GHz and an analogto-digital converter with a speed of up to 10.4 GSPS. The element base was selected for the receiving devices and the main parameters of the path were calculated. A number of examples are used to analyze the ways to increase the dynamic range of a radio receiver and the influence of element base parameters on the device performance. The main technical characteristics of the radio receiver for effective operation of modern radio monitoring systems and the ways to increase the dynamic range thereof are described.

Due to the rapid development and further improvement of radiation treatment technologies oncologists have an opportunity to precisely deliver individual dose distributions to the tumor, minimizing the doses obtained by critical organs and healthy structures. For the correct and successful application of these complex methods of radiation therapy, it was necessary to enforce the requirements for the technical and dosimetric parameters of the radiotherapy equipment. The purpose of the research is to determine the magnitude of the possible error for patients’ positioning during their radiotherapy treatments using medical linear accelerators by modeling the impact of the patient’s body on the treatment couch. To determine the values of a possible error, the authors have considered the design and characteristics of a typical treatment couch, developed a model of the “average” patient’s body (phantom), which allowed changing the load to the treatment couch with a step of 1 kg. The position parameters of treatment couches were determined for the main types of localization of radiation therapy for malignant tumors: head and neck tumors, breast tumors and pelvic tumors. Numerical values of the treatment coach deviations from prescribed horizontal position were experimentally established for a load from 40 to 180 kg for a treatment couch used at the N.N. Alexandrov National Cancer Centre of Belarus. Based on the obtained experimental data, the necessity to correct the patient's treatment conditions at the stage of treatment planning were confirmed in order to ensure the delivery accuracy of individual dose distributions as required by the radiation therapy protocols. Authors stated that an analysis of the dependence of the deviations in the dose delivered to the patients on the deviation of the radiotherapy table from its horizontal position should be carried out for each radiotherapy table used in clinical practice. The development and implementation of a mechanism that will allow considering this information when choosing the parameters of the patient’s treatment session and prescribing the dose for any localization of malignant neoplasms is needed.

The analysis of trends in the development of the automotive industry and well-known methods of automating vehicle control served the basis for us to propose an approach to organizing the transfer of vehicle control from an automated driving system to a person. The approach involves monitoring the vehicle performance and the systems that provide automated driving, the state of the environment and the driver's psychophysiological state, as well as road conditions on the upcoming path, predicting the place and time of transition of control to the driver, determining and regulating his/her readiness to take control if necessary. This approach is peculiar for in time of automated driving, the minimum level of the driver's readiness to operate the vehicle is constantly maintained, which is brought to optimal within a certain time before the scheduled transition to manual control. This two-level monitoring of the condition of drivers of highly automated vehicles will improve road safety both in cases of predicted and unexpected need for an emergency transition from automated to manual driving. The aim of the work is to develop a methodology for improving road safety with highly automated vehicles involved.

The object of research is a rock massif with various cross-sectional shapes of roadway. The purpose of work: computer modeling of stress-strain state and volumetric damageability in the neighbourhood of a mine roadway. The undisturbed rock massif has an initial stress-strain state (under its own weight) before a mine roadway is formed. Therefore, to determine the stress-strain state of the rock massif with the mine roadway, we must first calculate the stress state of the rock massif without the roadway and then take it into account as a pre-stressed state for the rock massif therewith. Damageability assessment of the rock massif with a mine roadway was carried out based on the obtained distributions of stresses and strains. We calculated volumetric damageability through the model of a deformed solid body with dangerous volume. Dangerous volume is a limited area where stresses or strains exceed the predetermined threshold. Calculation of dangerous volumes and integral damageability was carried out in the finite element package ANSYS. The program was written in APDL. The ratios between the existing and limiting stresses was calculated for each finite element. The elements for which this ratio exceeds unity will form a dangerous volume for the whole model. As a result, we have an array of finite elements constituting the dangerous volume and its value. The developed method for assessing damageability in the mine roadway neighbourhood takes into account various cross-sectional shapes of the mine roadway and its depth. The relevance of studying possible destruction regions using the model of a deformed solid body with dangerous volume was substantiated.

The use of microelectronic products in outer space is possible if protection is provided against special external influencing factors, including radiation effect. For digital integrated circuits manufactured using submicron CMOS processes, the greatest influence is exerted by radiation effects caused by exposure to a heavy charged particle. The use of special design tools in the development of dual-purpose microcircuits, with increased resistance to the impact of heavy charged particles, prevents single events from occurring. Thus, the use of modern software products for device and technological modeling in microelectronics when developing the element base of radiation-resistant microcircuits for space purposes will cut the time to develop new products and make it possible to modernize (improve performance) already existing device and circuitry solutions. The paper delivers the results of modeling the impacts of heavy charged particles with a magnitude of linear energy transfer equal to 1.81, 10.1, 18.8, 55.0 MeV·cm2/mg, corresponding to nitrogen ions 15N+4 with an energy E = 1,87 MeV; argon 40Ar+12 with an energy E = 372 MeV; ferrum 56Fe+15 with an energy E = 523 MeV; xenon 131Xe+35 with an energy E = 1217 MeV, on electrical characteristics of n-MOSFET device structure. The dependences of the maximum drain current IС on the motion trajectory of a heavy charged particle and the ambient temperature are shown.

In this paper we presents the results of tests of automatic fire alarm systems in terms of reducing the temperature effect on building structures (floors), air ducts of the exhaust smoke ventilation system. Tests were carried out to determine the efficiency of the antismoke ventilation system for the removal of combustion products through steel air ducts with a metal thickness of 1 mm, as well as analysis of the temperature regime on building structures, the air duct of the exhaust smoke ventilation system under fire exposure. For the warning system (SO) of the second type, CO-2 we used on the basis of ISO “Bolid” devices. The launch of a fire warning system is provided for: automatically from an automatic fire extinguishing system; remotely from manual fire detectors installed at emergency exits from the vehicle storage room. Two full-scale firing tests were carried out for passenger cars. During the tests, the vehicles were ignited from inside the passenger compartment. In the course of the fire tests proved that the antismoke control ventilation ducts retained their integrity and tightness, which was confirmed by the positive protocols of aerodynamic tests of the smoke control ventilation system. The air ducts of the exhaust smoke ventilation system retained their integrity, the flange connections of the air ducts retained their strength and tightness, the fastenings of the air ducts were not damaged and retained their functions. The tests established the following: limitation of the fire center in the horizontal projection of the vehicle (the perimeter of the vehicle); filling the volume of the storage room for vehicles with a smoke-steam-air mixture occurs in an avalanche manner over the entire height of the room; as a result of the avalanche-like filling of the room, the absence of a neutral zone (security zone) was determined. Based on the results of the tests, it is possible to make changes to the existing technical normative legal acts.

This paper presents the results of simulating the electron transfer processes in a three-dimensional semiconductor structure containing graphene and layers of boron hexagonal nitride using the Monte – Carlo method. Graphene is currently considered one of the most promising materials for the creation of new semiconductor devices with good performance for high frequency ranges. The use of graphene, which has high mobility of charge carriers, high thermal conductivity and a number of other positive properties, allows the development of new semiconductor devices with good output characteristics. The simulation allowed us to obtain the main characteristics of electron transfer, namely, dependence of speed, average energy, mobility on the strength of the electric field in a semiconductor structure containing a layer of graphene and boron nitride region. Electron transfer processes were simulated considering temperature variations of graphene and boron nitride layers, which is observed with increasing strength of the electric field in the structure. The analysis of the obtained dependencies showed that at small values of electric field strength, which does not exceed approximately 2.5 kV/cm, there is a nonlinear change in electron energy and temperature. At more significant values of electric field strength a quasi-linear change in temperature is observed. The similar course of dependence is observed also for the dependences of the average energy of electrons on the intensity of the electric field for the graphene layer.. The resulting dependencies of electron transfer characteristics can serve the basis for determining output characteristics in multi-layer semiconductor devices containing layers of graphene, boron hexagonal nitride and other materials.

The present work is devoted to determination of the dependence of the heating temperature of the silicon wafer on the lamps power and the heating time during rapid thermal processing using “UBTO 1801” unit by irradiating the wafer backside with an incoherent flow of constant density light. As a result, a mathematical model of silicon wafer temperature variation was developed on the basis of the equation of nonstationary thermal conductivity and known temperature dependencies of the thermophysical properties of silicon and the emissivity of aluminum and silver applied to the planar surface of the silicon wafer. For experimental determination of the numerical parameters of the mathematical model, silicon wafers were heated with light single pulse of constant power to the temperature of one of three phase transitions such as aluminum-silicon eutectic formation, aluminum melting and silver melting. The time of phase transition formation on the wafer surface during rapid thermal processing was fixed by pyrometric method. In accordance with the developed mathematical model, we determined the conversion coefficient of the lamps electric power to the light flux power density with the numerical value of 5.16∙10-3 cm-2 . Increasing the lamps power from 690 to 2740 W leads to an increase in the silicon wafer temperature during rapid thermal processing from 550°to 930°K, respectively. With that, the wafer temperature prediction error in compliance with developed mathematical model makes less than 2.3 %. The work results can be used when developing new procedures of rapid thermal processing for silicon wafers.

The search for fundamental physical laws which lead to stable high-temperature ferromagnetism is an urgent task. In addition to the already synthesized two-dimensional materials, there remains a wide list of possible structures, the stability of which is predicted theoretically. The article suggests the results of studying the electronic properties of MAX3 (M = Cr, Fe, A = Ge, Si, X = S, Se, Te) transition metals based compounds with nanostructured magnetism. The research was carried out using quantum mechanical simulation in specialized VASP software and calculations within the Heisenberg model. The ground magnetic states of twodimensional MAX3 and the corresponding energy band structures are determined. We found that among the systems under study, CrGeTe3 is a semiconductor nanosized ferromagnet. In addition, one is a semiconductor with a bandgap of 0.35 eV. Other materials are antiferromagnetic. The magnetic moment in MAX3 is localized on the transition metal atoms: in particular, the main one on the d-orbital of the transition metal atom (and only a small part on the p-orbital of the chalcogen). For CrGeTe3, the exchange interaction integral is calculated. The mechanisms of the formation of magnetic order was established. According to the obtained exchange interaction integrals, a strong ferromagnetic order is formed in the semiconductor plane. The distribution of the projection density of electronic states indicates hybridization between the d-orbital of the transition metal atom and the p-orbital of the chalcogen. The study revealed that the exchange interaction by the mechanism of superexchange is more probabilistic.

The commissioning of nuclear power plants in Belarus sets out wide tasking for the efficient usage of electrical energy in various electrical systems, instruments and devices. Specifically, it concerns the stationary and special-purpose electric motors. At present, they use bipolar motors with a collector – the switch of the motor armature windings during its rotation. However, there is a completely different type of motors that does not require a collector – the unipolar electric motor-generator. Some of its properties allow it to be used where the commutator motor is unsuitable, for example, in explosive and fire hazardous environments (sparking on the collector is unacceptable), in precision devices where extreme smoothness and vibration lack are required, etc. Physico-mathematical foundations of the unipolar motor-generator (moving media electrodynamics, Lorentz force, unipolar induction, magnetohydrodynamics) are described in a number of monographs and textbooks, for example, in [1–4]. The purpose of this article is to pay attention to the technical feasibility of the unipolar motor-generator in a design with separated conductors in the rotor drum.