The possibility of using materials in radiation protection shields when designing new and extending the service life of existing nuclear energy facilities requires knowledge or the ability to predict ...their radiation changes. The studies were carried out due to the lack of data sufficient to predict radiation changes in hardened Portland cement paste (HPCP) and concrete under the influence of gamma radiation when used as radiation shield materials for nuclear energy facilities. The research is based on published data on the effect of gamma radiation on concrete at irradiation temperatures of 20–30 °C and on HPCP at 70–375 °C. The author carried out computational and analytical studies to assess and establish the possibility of predicting radiation changes in HPCP under the influence of gamma radiation. The studies were conducted using the previously developed and tested method of analytical determination of radiation changes in concretes according to data on changes in their components. The formulas used in this method made it possible to determine (restore) the radiation changes of the HPCP from experimental data on radiation changes in concretes and aggregates. According to the available results of concrete irradiation, changes in linear dimensions and strength during compression of HPCP under the action of only gamma radiation were calculated (restored). The dependences of radiation changes in HPCP on the magnitude of the absorbed dose in the range from 3.8104 to 4.7108 Gy after irradiation at 20–30 °C were established. According to the available data on the irradiation of HPCP with gamma radiation at temperatures from 70 °C to 375 °C, the effect of the irradiation temperature on radiation changes in the HPCP was revealed. Mathematical expressions that approximate the established dependencies are selected. On the basis of the obtained mathematical expressions, radiation changes in the linear dimensions and strength of HPCP for compression, caused only by the action of gamma radiation, after irradiation to the values of absorbed doses from 3104 Gy to 11010 Gy were calculated. The calculations of radiation-thermal changes in the linear dimensions and strength of HPCP under the action of gamma radiation and heating after irradiation to the values of absorbed doses from 3104 Gy to 11010 Gy and the accompanying heating at temperatures from 20 °C to 500 °C were estimated.
In the paper, the processes of changing the technical state of the crankshaft due to deformation and fatigue failure are considered. The defect method is presented, which allows to estimate the ...degree of fatigue damage of the crankshaft and to choose the way of restoration of the crankshafts
The formation of explosive gas mixtures due to the evolution of hydrogen from concrete structures for radiation protection of nuclear power buildings should be taken into account when designing and ...operating them. However, this requires methods for estimating and predicting the radiation evolution of hydrogen.This paper was done due to the lack of analytical methods for determining the gas evolution from concrete and their components under the influence of gamma radiation. In the work, based on the available experimental data, the model was selected, checked, and adjusted for an analytical description of the process of hydrogen evolution from concrete on aggregates that do not contain water under the influence of gamma radiation.When selecting the model, it was assumed that the evolution of hydrogen from concrete on aggregates that do not contain water under the effect of gamma radiation is mainly due to the radiation decomposition of evaporable water (free water and adsorbed water) from hardened cement paste (cement stone) and is determined by the amount of evaporable water in the material and the power of the absorbed dose of gamma radiation. It was taken into account that the amount of evaporable water during irradiation decreases with increasing time and temperature of irradiation.Verification of the possibility of using the selected model, its necessary adjustment and determination of the main parameters of this model was performed on the basis of available experimental data on the evolution of hydrogen from Portland cement stone under the influence of gamma radiation. We used experimental data on the release of hydrogen and water from cement stone containing and practically not containing evaporable water when irradiated with gamma rays with an average energy of 1.25 MeV at the absorbed dose rate of 0.87 kGy/h, 3.84 kGy/h and 7.05 kGy/h at temperatures of 25, 40 and 60 °C for up to 2 months. The dependence of the model parameters on the absorbed dose rate of gamma radiation and the irradiation temperature is shown. For cement stone dried at 120 °C to remove evaporable water, the amount of residual evaporable water (residual evaporable water or decomposed chemically bound water) was studied and determined.
The article discusses the possibility of using blended biofuels from rapeseed oil (RO) as fuel for a diesel engine. RO blended diesel fuel (DF) and emulsified multicomponent biofuels have been ...investigated. Fuel physicochemical properties have been analyzed. Experimental tests of a diesel engine D-245 in the operating conditions of the external characteristic curve and the 13-mode test cycle have been conducted to investigate the effect of these fuels on engine performances. CFD simulations of the nozzle inner flow were performed for DF and ethanol-emulsified RO. The possibility of a significant improvement in brake thermal efficiency of the engine has been noted. The efficiency of using blended biofuels from RO as a motor fuel for diesel engines has been evaluated based on the experimental test results. It was shown that in comparison with the presence of RO in emulsified multicomponent biofuel, the presence of water has a more significant effect on NOx emission reduction. The content of RO and the content of water in the investigated emulsified fuels have a comparable influence on exhaust smoke reduction. Nozzle inner flow simulations show that the emulsification of RO changes its flow behaviors and cavitation regime.
Significance. An increasing number of students with a variety of health conditions necessitates a discussion of the student adherence to healthy lifestyle principles. The Purpose of the study was to ...analyze the attitude of young people towards a healthy lifestyle and their health, to assess their awareness of measures to maintain health, including reproductive health. Material and methods. The method of sociological survey according to the author's questionnaire was used. 1009 young people aged 19-23 from the Omsk Pedagogical University, Omsk Technical University, Siberian Automobile and Road University were interviewed. During statistical data processing, extensive and intensive indices were calculated. Statistical significance of differences in the indicators was determined by Student's t-test and chi-squared test. Results. The contradictions between a rather high self-rated adherence to the principles of healthy lifestyle among students and insufficient readiness to use health technologies in everyday life have been identified. A comparative analysis of the students' answers by gender was carried out; statistically significant differences were established. Insufficient level of awareness of the interviewed persons about measures of health maintenance, including reproductive health, were established. Conclusion. A range of problems affecting adherence to the principles of healthy lifestyle among students (peculiarities of education, inclination for bad habits, insufficient awareness of the respondents about contraceptives and methods of contraception) has been outlined. The role of educational institutions in health promotion is highlighted.
The article presents the results of computational studies of the radiation changes in serpentinite concretes of "dry" radiation shield of the Water-Water Energetic Reactor (WWER/VVER) type of nuclear ...power plants built in the Russian Federation and other countries. The research was carried out in connection with the increase in radiation loads on the concrete of the "dry" protection of modern nuclear power plants, and also in connection with the possible use in "dry" protection of the modern nuclear power plants of concretes with serpentinite aggregates which mineral composition and structure differ from the composition and structure of the previously used serpentinites. The calculation studies were performed using the developed and experimentally tested methods for the analytical determination of radiation and thermal changes in concretes and their components. It was found out that the relative number of displaced by irradiation atoms from 0.026 to 0.1, degree of perfection of the crystal structure of serpentinite minerals, availability of impurities in serpentinite minerals (magnetite, chlorite, olivine, pyroxenes, hornblende, brucite, magnesite, calcite, dolomite, ankerit, mica, feldspar in quantity from 0 to 40%, medium mineral grain size in the range of 0.0001 cm up to 0.02 cm influence on the radiation changes in the volume and strength of serpentinite concretes. There was also performed comparison of radiation and thermal changes. The research has showed that the lowest radiation changes will occur in the serpentinite concrete with aggregates consisting only of serpentine, especially with imperfect structure. The availability and quantity of magnetite, chlorite, calcite, brucite, feldspars and mica show insignificant influence on the radiation changes. The presence of dolomite, magnesite, ankerite and especially olivine, hornblende, pyroxenes with an increase in their volume content, as well as growth in the size of grains of minerals, the radiation changes in serpentinite concretes may grow up to 2-4 times. By increasing the duration of exploitation and power capacity of the reactor, as well as by extending the service life of a nuclear power plant, the radiation changes in the serpentinite concretes of "dry" radiation shield may grow up to 6-12 times.
Background. In connection with the pronounced trend to constant intensification of the global information space, the inclusion of immersive technologies in the educational process and training of ...healthcare professionals has significantly intensified in recent years. They are distinguished from traditional educational technologies by immersion, presence and interactivity that provide a developing effect (Tishkov D.S., 2020). However, the active implementation of such programmes requires an understanding of their place in the education system and the possible risks of application, not only from the point of view of the effectiveness of mastering the necessary professional competencies, but also from the subjective experiences of participants in the educational process and their psychological well-being. Objectives. The aim is to analyse psychological aspects of the use of VR technologies in the medical education system and the problem of developing a comprehensive system for assessing the safety and effectiveness of educational VR programmes. Methods. The systematic review and theoretical analysis of the problem of using VR technologies in the medical education system. Results. The introduction of educational VR programmes and the use of virtual reality tools did not receive methodological justification. Despite the prevalence and speculative effectiveness of VR technologies, there is still no reliable data on their teaching potential in the educational process. The use of virtual reality in the medical education system requires a systematic interdisciplinary analysis and discussion by a community of specialists. Conclusion. The introduction of VR technologies into the educational system requires a comprehensive psychological, pedagogical, and medical analysis. The discussion of new technologies and means of the educational process should affect a number of psychological aspects, such as: determining the zone and focus of the use of virtual reality in medical education; analyzing social components of educational activities; forming an expert community for the development, control of implementation, evaluation of the effectiveness and safety of educational VR programmes; developing methodological, didactic and methodological principles for educational programmes using VR technologies.
•The cessation of increase of fuel consumption under the injection pressure above 350 MPa is found experimentally;•High heating of fuel during compression and while flowing through an injector is ...detected under ultra-high pressures;•Methods for calculating the heating of fuel when injected under ultra-high pressures are described.
The cessation of increase of fuel consumption under the injection pressure above 350 MPa is experimentally found. The aim of the work is to describe the causes of the phenomenon and to find its adequate mathematical description.
The experimental results are given in the article, which were obtained by passing fuel through an orifice and a diesel injector. Methods for calculating fuel heating and consumption during injection at ultra-high pressures are described. It was found that fuel heating occurs due to several factors, each of which can provide heating up to 50 … 200 °C at pressures of 200 … 400 MPa.
On the one hand, the heating of fuel under ultra-high pressures brings the flow regime in nozzle openings to supercritical due to the decrease of the velocity of sound. On the other hand, the overheated fuel worsens the operation of a high-speed electromagnetic drive and, hence, the quality of engine control. The experience in designing Common Rail systems is still insufficient. There is lack of such an experience for ultra-high pressures. Therefore, the creation of methods of calculating the heating of fuel in the nozzle is very relevant today.
The work (in connection with the small study of the effects of gamma ray on concretes and their components) contains the results of calculation and analysis of radiation changes of concrete ...aggregates under the influence of gamma ray on the basis of analytical methods developed previously during the neutron irradiation process. The possibility of using these analytical methods in the case of exposure to gamma ray was substantiated. The relationship of the absorbed doses of gamma ray of different energies with the number of atoms displaced during irradiation was established. There is an assessment of radiation changes in the volume and strength of the main types of rocks - aggregates of concrete (igneous, sedimentary rocks and ores) under the influence of gamma ray with an average energy of 2 MeV and 5 MeV after irradiation to absorbed doses of 105 to 1011 Gy at 30 °C, 100 °C and 300 °C. For this, from the beginning, the radiation changes of the main rock-forming minerals were calculated, and on the ground of them, the radiation changes of rocks of concrete aggregates were calculated. It has been established that noticeable radiation changes of considered minerals and rock aggregates will occur only at absorbed doses of gamma ray of more than 1ꞏ109–1ꞏ1010 Gy of gamma rays with an energy of 5 MeV and of 3ꞏ109–3ꞏ1010 Gy for gamma rays with an energy of 2 MeV. The number of radiation changes grows with a rise in the absorbed dose and significantly decrease with an increase in the irradiation temperature for silicate class minerals and silicate rocks. The greatest radiation changes under the influence of gamma ray at 30 °C are observed in silicate minerals and rocks, especially olivine pyroxenes, hornblende, dunite, peridotite, pyroxenite, and gabbro. Moreover, even with an absorbed dose of gamma ray of 1011 Gy, the radiation changes are not large (increase in volume is not more than 0.36 %, decrease in strength is not more than 8.7 %). As the temperature increases, the ratio in the magnitude of radiation changes of different materials changes.
This paper considers a relevant method to ensure communication and object location in vast agricultural areas. To solve this problem an operational scenario was proposed, an approach, involving a ...complex of several UAVs, which establish an AESA; an algorithm for building an optimal path, along which the UAV complex moves, formulas for calculating AESA direction pattern for linear and flat formations of UAV groups, formulas for calculating time, required for terrain scanning with various areas. In such complex on each UAV an antenna with phase shifter is mounted. The paper also considers modeling and comparison of different approaches to motion of an UAV complex for terrain scanning. Due to application of active electronically scanned arrays, the proposed localization method is characterized by high noise immunity, is better shielded from noise, less dependent on weather conditions and appliable at night time. Unlike other methods, it supports wide-range transmission and reception of data. Thereby, application of AESA makes this method robust and practical for localization and communication establishment, whereas the proposed algorithm for building of optimal path, along which the robotic complex moves, enables to reduce time, required for area scanning. Consequently, this method allows achieving the shortest distance that the UAV complex has to cover.
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