Models of activated recrystallization on isolated grain boundaries in polycrystals

New phenomenological models of recrystallization of a polycrystalline material in two regimes are proposed taking into account the finite width of grain boundaries. The solutions are obtained in an analytical form for the initial-boundary value problems formulated. They describe the distributions of the concentration of impurities diffusing from the surface coating, both in the grain boundary and in the grain itself in the recrystallized region. The speed of the recrystallization front movement is indicated, which agrees with the types of the corresponding kinetic dependences observed in experiments.

Constructing a method for assessing the effectiveness of using protective barriers near highways to decrease the level of air pollution

Highways are an intensive source of environmental pollution. Atmospheric air is exposed to the fastest anthropogenic influence. Therefore, a particularly important task is to minimize the level of air pollution near the highway. An effective method for solving this problem is the use of protective barriers of various shapes installed near highways. At the stage of designing these protective structures, an important task arises to assess their effectiveness. Estimation of the effectiveness of protective barriers by the method of the physical experiment takes considerable time to set up and conduct an experiment, as well as analyze the results of physical modeling. This method is not always convenient during design work. An alternative method is the method of mathematical modeling. For the designer, it is very important to have mathematical models that make it possible to quickly obtain a predictive result and take into consideration a set of important factors on which the effectiveness of the protective barrier depends. A method has been devised that makes it possible to assess the effectiveness of using protective barriers to reduce the level of air pollution near the highway. It was found that an increase in barrier height by 80 % leads to a 22 % decrease in the concentration of impurities behind the barrier. It was established that applying a barrier with a height of 1.5 m leads to a 26 % decrease in the concentration of impurities in buildings adjacent to the highway. A method has been devised to assess the effectiveness of using absorbent "TX Active" surfaces on the protective barrier located near the highway. This study's result revealed that the application of a barrier with one "TX Active" surface leads to a decrease in the concentration of NO behind the barrier by an average of 43 %. When using a barrier with two "TX Active" surfaces, a decrease in the NO concentration behind the barrier is 85 % on average

Unconventional non-Fermi liquid properties of two-channel Anderson impurities system

A theory for treating the unconventional non-Fermi liquid temperature dependence of physical quantities, such as the resistivity, in the Pr-based two-channel Anderson impurities system is developed. It is shown that their temperature dependences are essentially the same as those in the pure lattice system except for the case of extremely low concentration of Pr ions that is difficult to realize by the controlled experiments. This result is consistent with recent observations in diluted Pr-1-2-20 system Y1−xPrxIr2Zn20 (x = 0.024, 0.044, 0.085, and 0.44) reported in Yamane et al. Phys. Rev. Lett. 121, 077206 (2018), and is quite different from that in the case of single-channel Anderson impurities system in which the crossover between behaviors of the local Fermi liquid and heavy Fermi liquid occurs at around moderate concentration of impurities as observed in Ce-based heavy fermion system La1−xCexCu6.

APLICATION OF THE GAUSSIAN MODEL IN RESEARCH SPREADING AIR POLLUTION

The article deals with the application of the Gaussian distribution for calculating the concen-tration of pollutants. When using the principle of superposition, we have the opportunity to obtain models for calculating the concentration of impurities from a point source of continuous action, in-stantaneous areal and instantaneous volumetric sources. The obtained standard deviations make it possible to assess the effect of air turbulence on the dispersion of pollutants. The first Gaussian model allows one to obtain a diffusion model of a local small-scale space and make predictions, then, based on the Gaussian model of the study, a modified model is obtained for other reliefs and weather conditions. Therefore, the modeling accuracy and applicable conditions are difficult to cope with the needs of large-scale complex meteorological conditions of air quality models.

Influence of bulk defects in SnS absorber layer on optical and electrical properties of solar cell

In this research, the effect of bulk defect on the performance of the solar cell was studied by using the AFORS-HET simulation program. This was done by varying the density of defects including both Acceptor-like and donor-like within the SnS absorption layer. The thickness of the SnS layer was changed from 600nm to 9000nm with the change in bulk defect density in the same layer from (1E10 to 1E17 cm−3). The results showed that when the density of defects is less than 1E14cm−3, it has no effect on the performance of the solar cell, but its effect appears after this concentration, On the contrary, it is the effect of thickness, the results showed that the change in thickness at the defect density of E16cm−3 does not affect on the optical and electrical properties. Also, the results showed that the effect of defects is greatest at low concentrations of Na impurities, and this effect begins to decrease with increasing the concentration of impurities.

Evaluation of Impurity Concentration Process and Mitigation Operation in Fuel Cell System for Using Biogas

For a low-carbon society, it is necessary to extract hydrogen for fuel cells from biogas rather than from fossil fuels. However, impurities contained in the biogas affect the fuel cell; hence, there is a need for system and operation methods to remove these impurities. In this study, to develop a fuel cell system for the effective utilization of biogas-derived hydrogen, the compositional change and concentration of impurities in the hydrogen recirculation system under actual operation were evaluated using process simulation. Then, the mitigation operation for performance degradation using simple purification methods was evaluated on the proton exchange membrane fuel cells (PEMFC) stack. In the process simulation of the hydrogen recirculation system, including the PEMFC stack, the concentration of impurities remained at a level that did not pose a problem to the performance. In the constant voltage test for a simulated gas supply of biogas-derived hydrogen, the conditions for applying the methanation reforming and air bleeding methods were analyzed. As a result, methanation reforming is more suitable for supplying biogas-containing CO to the PEMFC stack for continuous operation.

COMPARATIVE EVALUATION OF CONTROL METHODS FOR WATER PURIFICATION FROM POLLUTION

Article is devoted to comparison of methods for assessing changes in concentration of pollutants in aqueous solutions, and to analysis of factors involved in these processes. The distortion of parameters of Earth's ecosphere due to various influence of technogenic factors now become more and more threatening. Such pollutants, in particular, are dosage forms that enter soil and water areas, violate their natural conditions of functioning, and, as a result, pose a serious danger to both animals and humans. The processes of interaction of drugs with natural formations are very diverse; therefore, it is difficult to develop sufficiently effective methods of purification. Recently, much attention has been paid to biological methods of purification, when the ecosystem restores its characteristics and with the help of natural purifiers, in particular, the use of plants that quite universally absorb various impurities, including drugs. The paper presents the results of experiments evaluating the change in the concentration of impurities in different ways when purifying water from impurities using the eichornia plant.

CFD Optimization of the Resistivity Meter for the IFMIF-DONES Facility

A detailed study of lithium-related topics in the IFMIF-DONES facility is currently being promoted and supported within the EUROfusion action, paying attention to different pivotal aspects including lithium flow stability and the monitoring and extraction of impurities. The resistivity meter is a device able to monitor online non-metallic impurities (mainly nitrogen) in flowing lithium. It relies on the variation of the electric resistivity produced by dissolved anions: the higher the concentration of impurities in lithium, the higher the resistivity measured. The current configuration of the resistivity meter has shown different measuring issues during its operation. All these issues reduce the accuracy of the measurements performed with this instrument and introduce relevant noise affecting the resistance value. This paper proposes different upgrades, supported by CFD simulations, to optimize lithium flow conditions and to reduce measurement problems. Owing to these upgrades, a new design of the resistivity meter has been achieved, which is simpler and easier to manufacture.