bluuebunny/crossref_metadata_2025 huggingface dataset:
Features of functional dependence of random phenomena and values in social being in conditions of its unstability (the environmental position)
Authors: Drotyanko Lyubov , Kharchenko Julia , Kharchenko Sergej , Kolomiets Oleg
Published: March 2021

The analysis of the phenomenon of “random” and the principle of the relationship of random phenomena in social reality in the conditions of its instability has been conducted. On this basis, the key task was the conceptualization of the random phenomena in the scales of typology of fundamental and social interactions. It has been confirmed that the concept of “random” in terms of instability is more effectively described through ontological, phenomenological, transcendental and functional approaches and in the context of environmental position. A probability principle was applied when describing the randomness of abstract values. It has been proved that even minor aberrations at one or another point of space at different systemic levels of the material world can profoundly change the metric properties of systems, cause their instability. The results of the research confirmed that the unstable social system does not return to the state of equilibrium from which it has came out for different reasons, but continuously it moves away from it or makes unacceptably large fluctuations around it. And functional dependence between random phenomena and quantities under conditions of social instability is possible as stability of a different kind.
Online education in new period of sustainable development after the pandemic
Authors: Barabash Oksana , Sknarev Dmitry , Maslova Irina , Bereznyatskaya Marina , Prakhova Alena
Published: March 2021

The article is devoted to the problem of assessing the effectiveness of the online distance learning format, based on the results of work during the first wave of the COVID-19 pandemic. The purpose of the article is to identify specific problems faced by students of various education profiles: natural science and humanitarian. The objectives of the article are to analyze the scientific literature on the research topic, as well as present the results of the empirical research conducted by the authors among two groups of respondents. The methodology of the article is based on a systematic approach and includes a group of general scientific methods (analysis, synthesis, deduction, induction), as well as special methods: content analysis of scientific literature on the research topic, the method of sociological research (questionnaire survey), as well as the method of statistical analysis. Based on the results of the study, the authors came to the following conclusions: the online format of distance learning is not compatible with a number of natural science disciplines, which leads to a sharp decrease in the quality of education, especially in the field of applied sciences.
The effects of race track surface condition on the racing time of Orlov trotters
Authors: Gladkikh Marianna , Kuznetsova Olga
Published: March 2021

Race speed is one of the main indicators by which trotting horses are estimated. In addition to the horse genotype, race speed is also determined by the influence of environmental factors, such as feeding, keeping, training, and testing conditions. These conditions include of race track surface condition, the rider’s qualifications, season of the year, weather conditions. In this paper the influence of race track surface condition on the accuracy of assessing race time is considered. The data of horse trials of Orlov trotters at the Moscow hippodrome were used. The race time of 256 horses at a distance of 1600 m was assessed. Depending on the weather conditions and the track surface, 9 different track conditions were identified. For the analysis we used data on stallions and mares aged 4 years and older without disaggregation by sex, since there were no significant differences between the average race speed of stallions and mares and it was shown that it was the horses of the older age group that were reliably characterized by the highest average race time with minimal races per horse. It was found that the strength of the influence of the variety of race tracks on the variety of assessments of race time is reliable and amounted to 23.5%. When analyzing the group of the fastest horses, this indicator turned out to be higher and amounts to 43.8%. It is also shown that the selection of horses for breeding work is more expedient and accurate to carry out according to the average race time of the horse for a number of races, and not according to its best result, since in this case the stability of performances is not taken into account.
Structural analysis of consequences of corruption in the environmental sector in modern society
Authors: Burukin Vadim , Vezlomtsev Victor , Vezlomtseva Svetlana , Zvyagina Alena , Sevalnev Vyacheslav
Published: March 2021

This article shows the dialectic influence of phenomenon of corruption on the social reality of modern society. The main approaches to assessing the consequences of corruption processes are considered. Through the prism of these approaches, a structural analysis of consequences of corruption in economic, political, social and spiritual spheres of society is carried out. Based on the philosophical principle of reflection, factors of social danger of corruption are identified, main manifestations of corruption affecting the formation of the image of social reality are described. The article provides a critical analysis of the revisionist approach. Its supporters believe that corruption can be viewed as a natural phenomenon that manifests itself in the transitional periods of development of society, with a change in the norms of its functioning and the lack of consensus, as well as a kind of mediator that unites the emerging privileged and excluded strata a changing society. The main function of corruption within this approach is to preserve the unity and maintain the integrity of socio-economic system in certain conditions, after which corruption should disappear. The laws of dialectics are manifested in this area of human interactions. Therefore, we can talk about the socially constructive function of studied social phenomenon. It is shown that the ratio of constructive and destructive consequences of corruption manifestations in various social systems and at different stages of their historical development varies.
Structural analysis of corpus of the lawful infliction of harm to the environment under circumstances precluding criminality
Authors: Zakharova Svetlana , Novikova Ludmila , Maltseva Svetlana , Merkuriev Victor
Published: March 2021

One of the institutions of criminal law, which is of undoubted interest among forensic scientists, are the circumstances precluding the criminality of an act. This interest is due to the controversy of certain legislative provisions, entailing the prosecution of persons acting under the conditions of the legality of these circumstances. When characterizing the circumstances precluding the criminality of an act, included in Ch. 8 of the Criminal Code of the Russian Federation, the law enforcement officer always proceeds from the assessment of the harm already caused to the interests protected by law and on the compliance of the harm with the conditions enshrined in the law. Acts committed in a state of circumstances precluding criminality are legally significant, since the law associates the emergence of two types of legal relations with these circumstances. In the first case, circumstances change the criminal-legal nature of the act and transfer it to the category of unpunished, despite causing harm. In the second, in the presence of circumstances in conditions of violation of the legality of an action (inaction), the harm caused is qualified as a crime. This necessitates a criminal-legal assessment of the harm caused from the standpoint of the theory of corpus delicti. At the same time, the substantiation of the legality of the actions of a person under the conditions of the circumstances precluding the criminality of an act is established by identifying in his action the signs of the corpus of lawful infliction of harm. The need for a structural analysis of the composition of the lawful infliction of harm is primarily due to the need to distinguish between certain types of circumstances that exclude crime, in order to correctly qualify the committed acts and prevent unjustified criminal prosecution for its infliction. The corpus of the lawful infliction of harm should be considered by highlighting the objective and subjective signs of the circumstances precluding the criminality of an act by analyzing the object, objective side, subject and subjective side of an act.
Social adaptation of convicts in the urban planning and greening industry
Authors: Brovkina Alexandra , Rudenko Alexandr , Korneev Sergey , Temirkhanov Maksim , Tarakanov Ilya
Published: March 2021

Institutions of civil society play an important role in the process of re-socialization of convicts and their social adaptation. In the process of joint activities of penitentiary system (hereinafter referred to as the PS) with representatives of the public, there are being addressed issues of social adaptation of persons after release from prison, assistance to convicts in the restoration, maintenance and development of socially useful ties, preparation for release, labor and household arrangements, medical and social security, as well as the organization of leisure, education for convicts, their moral, legal and cultural education and development. At the same time, the fulfillment of these post-penitentiary tasks satisfies a number of needs of modern state, in particular, in the urban planning industry. This study examines the experience of interaction between the Federal Penitentiary Service of Russia and the Volnoe Delo Social Innovation Fund in the field of employment of convicts, incl. at construction sites. Based on the analysis of implementation of the program for social support of persons in difficult life situations, a conclusion is made about the need to individualize educational work and targeted assistance to convicts; stimulation to change motivational attitudes and moral values; wide demand for the labor of convicts in the urban planning industry.
Environmental law and reconciliation with a representative of power under criminal law of Russia
Authors: Zakharchuk Sergey
Published: March 2021

Domestic criminal legislation provides for possibility of releasing from criminal liability a person who has committed a crime of small or medium gravity for the first time, provided that he/she has reconciled with the victim and made amends for the harm caused. Comparative legal analysis shows that similar norms are found in the criminal laws of foreign states. The article discusses issues related to the possibility of terminating a criminal case in connection with the reconciliation of parties in the event that a victim is a representative of authorities. As a result of analysis of scientific positions on this issue, as well as corresponding law enforcement practice, ambiguity in approaches to its solution was revealed. The presence of certain contradictions in the area under study is also confirmed by statistical information. The author substantiates the position on the need to establish a ban on exemption from criminal liability in connection with reconciliation with the victim, if a crime is committed against justice or the order of administration, and the victim is a representative of authorities. In this case, the victim acts as an additional objective manifestation of encroachment, and therefore, reconciliation cannot eliminate the harm done to the interests of the state - the main object of criminal encroachment. In order to resolve the problem, it is proposed to amend Article 76 of Criminal Code of Russian Federation.
Impact du FGF21, une hormone du métabolisme énergétique, sur la reproduction
Authors: Bourdon Guillaume , Froment Pascal , Ducluzeau Pierre Henri
Published: March 2021

L’obésité et l’insulinorésistance sont les principales maladies non infectieuses qui progressent le plus dans le monde. Elles favorisent l’hypertension, les maladies cardio-vasculaires, mais conduisent aussi à une chute de la fertilité dans les deux sexes. Le FGF21, découvert dans les années 2000, est lié au statut énergétique de l’organisme et améliore l’insulinorésistance. Via ses récepteurs (FGFR1c, 3c,et 4), il agit sur le foie et au niveau d'organes régulant le métabolisme glucido-lipidique, mais aussi sur le cerveau et les gonades. Des données récentes sont ainsi en faveur d’un rôle régulateur de FGF21 sur la fertilité, tant féminine que masculine. Mais quel rôle FGF21 peut-il jouer dans la reproduction ? Dans cette revue, nous avons examiné les différentes activités que présente cette hormone sur la reproduction, ouvrant la voie à une éventuelle utilisation thérapeutique en cas d’infertilité.
Numerical analysis of the carbon containing pellets direct reduction process
Authors: Li Nan , Wang Feng , Zhang Wei
Published: March 2021

In view of the carbon-containing composite pellets direct reduction process in rotary hearth furnace, a mathematical model coupling heterogeneous chemical reaction kinetics, heat and mass transfer of this process was established. The effects of furnace temperature (from 1273.15 K to 1673.15 K) and pellet radius (from 6 mm to 16 mm) on the direct reduction of carbon-containing composite pellets were studied by adopting computational fluid dynamics software. The pellet temperature and composition changes under different operating conditions were analyzed. CO and CO2 fluxes, heat fluxes on the pellet surface were especially studied. Total heat absorption by the pellet, CO and CO2 overflow from the pellet surface together with pellet degree of metallization (DOM) and zinc removal rate (ZRR) were calculated. Results show that with the increasing of furnace temperature or the decreasing of the pellet radius, the temperature difference between pellet surface and its center and the final DOM, ZRR increased. The larger the pellet radius, the smaller the heat absorption, also the smaller CO and CO2 overflow. But heat absorption and CO overflow per unit volume are higher. There is an optimal pellet radius with high CO utilization efficiency. Pellet porosity decreases at first and then increases with reducing time. It is also found that effective thermal conductivity is a major factor limiting the pellets temperature increasing. The reduction sequence of the pellets is Fe2O3→Fe3O4→FeO→Fe.
Electric Power Supply Chain Networks Design featuring Differential Pricing and Preventive Maintenance
Authors: Tsao Yu-Chung , Vu Thuy-Linh , Lu Jye-Chyi
Published: March 2021

The electric power supply chain network plays an important role in the world economy. It powers our homes, offices, and industries and runs various forms of transportation. This paper considers an electric power supply chain network design problem featuring differential pricing and preventive maintenance. We demonstrate that this general model can be formulated as the centralized and decentralized supply chain models. A continuous approximation approach is used to model the problems. The objective of these models is to determine the optimal power plants’ service area, electricity price, and preventive maintenance budget while maximizing the total network profit or the own organization’s benefits. Our model is applied to the case of a power company in northern Vietnam. We show that the proposed approach can be used to address real-world cases effectively. The results demonstrate that the use of differential pricing policy and preventive maintenance could much enhance power company profit.
Infographics in TIVA
Authors: Chokshi Tushar M.
Published: March 2021

Infographics are a new way of visually communicating information in a colorful and concise manner. They are becoming very popular in medical field since the last decade. Through infographics, one can understand the subjects through text, graphics, and images. Total intravenous anesthesia (TIVA) is a technique of general anesthesia (GA) given via intravenous (IV) route exclusively. In perspective of infographics, TIVA is far more understandable through its simple format. TIVA is also more advantageous than inhalational anesthesia. It avoids the deleterious effects of immunosuppressant and lacks any respiratory irritation, thus providing a good alternative anesthesia technique. Many peripheral surgeries can be done with the patient breathing spontaneously without any airway device, thus avoiding airway instrumentation, leading to droplet and aerosol generation. IV agents can be utilized to provide sedation during regional anesthesia (RA), which can easily be escalated to contain pain due to sparing of blocks or receding neuraxial anesthesia. The present narrative review focuses on the infographics in TIVA technique, providing highlights pertaining to its importance.
Brokerage at the science–policy interface: from conceptual framework to practical guidance
Authors: Gluckman Peter D. , Bardsley Anne , Kaiser Matthias
Published: March 2021

This article analyses the conceptual framework of brokerage at the science–policy interface as an important boundary function to support trusted and transparent government decision-making. Policymaking involves a broad range of considerations, but science advice and evidence is critical to help inform decisions. However, mechanisms for requesting and receiving advice from the scientific community are not straightforward, considering that the knowledge needed generally spans multiple disciplines of the natural and social sciences. Once evidence has been appropriately synthesized, there remains the need to ensure an effective and unbiased translation to the policy and political community. The concept of knowledge brokerage revolves around an understanding of the ontologies, cultures and languages of both the policy community and the science community, in order to effectively link the two bidirectionally. In practical terms, this means ensuring that the information needs of the former are understood, and that the type and form of information offered by the latter aligns with those needs. Ideally, knowledge brokers act at the interface between researchers/experts and decision-makers to present evidence in a way that informs policy options but does not determine policy development. Conceptually, negotiating this interface involves acknowledging that values are embedded in the scientific process and evidentiary synthesis, and in particular, in considering the inferential risks inherent in making evidence claims. Brokers are faced with navigating complex policy dynamics and balancing information asymmetries between research providers and users. Building on the conceptual analysis and examination of the nuances of brokerage observed in practice, we propose a set of guidelines to translate the concepts of brokerage to practical application.
Synchronization and locking in oscillators with flexible periods
Authors: Savinov Mariya , Swigon David , Ermentrout Bard
Published: March 2021

Entrainment of a nonlinear oscillator by a periodic external force is a much studied problem in nonlinear dynamics and characterized by the well-known Arnold tongues. The circle map is the simplest such system allowing for stable N:M entrainment where the oscillator produces N cycles for every M stimulus cycles. There are a number of experiments that suggest that entrainment to external stimuli can involve both a shift in the phase and an adjustment of the intrinsic period of the oscillator. Motivated by a recent model of Loehr et al. [J. Exp. Psychol.: Hum. Percept. Perform. 37, 1292 (2011)], we explore a two-dimensional map in which the phase and the period are allowed to update as a function of the phase of the stimulus. We characterize the number and stability of fixed points for different N:M-locking regions, specifically, 1:1, 1:2, 2:3, and their reciprocals, as a function of the sensitivities of the phase and period to the stimulus as well as the degree that the oscillator has a preferred period. We find that even in the limited number of locking regimes explored, there is a great deal of multi-stability of locking modes, and the basins of attraction can be complex and riddled. We also show that when the forcing period changes between a starting and final period, the rate of this change determines, in a complex way, the final locking pattern.
The effects of sensory quantization and control torque saturation on human balance control
Authors: Gyebrószki Gergely , Csernák Gábor , Milton John G. , Insperger Tamás
Published: March 2021

The effect of reaction delay, temporal sampling, sensory quantization, and control torque saturation is investigated numerically for a single-degree-of-freedom model of postural sway with respect to stability, stabilizability, and control effort. It is known that reaction delay has a destabilizing effect on the balancing process: the later one reacts to a perturbation, the larger the possibility of falling. If the delay is larger than a critical value, then stabilization is not even possible. In contrast, numerical analysis showed that quantization and control torque saturation have a stabilizing effect: the region of stabilizing control gains is greater than that of the linear model. Control torque saturation allows the application of larger control gains without overcontrol while sensory quantization plays a role of a kind of filter when sensory noise is present. These beneficial effects are reflected in the energy demand of the control process. On the other hand, neither control torque saturation nor sensory quantization improves stabilizability properties. In particular, the critical delay cannot be increased by adding saturation and/or sensory quantization.
Scattering by lossy anisotropic scatterers: A modal approach
Authors: Kossowski N. , Chen Parry Y. , Wang Q. J. , Genevet P. , Sivan Yonatan
Published: March 2021

Scattering from anisotropic geometries of arbitrary shape is relatively difficult to interpret physically, involving the intricate interplay between material and geometric effects. Insights into complex scattering mechanisms are often enabled by modal methods that decompose the response into the well-understood multipolar resonances. Here, we extend the generalized normal mode expansion to lossy and anisotropic scatterers. Unique to the method is that it decomposes the total response of any anisotropic resonator into the modes of the corresponding isotropic resonator. This disentangles the material and geometric contributions to the scattering of any anisotropic resonator. Furthermore, the method can identify absorption and scattering resonances with separate sets of modes. We illustrate our method by considering an infinitely long cylinder with concentric metallic/dielectric layers, targeting the complex case of an effective hyperbolic response. We show that by scanning the material composition of the hyperbolic medium, we can achieve any desired scattering effect, including backscattering cancellation.
Surface wave scattering by multiple flexible fishing cage system
Authors: Selvan Siluvai Antony , Gayathri R. , Behera Harekrushna , Meylan M. H.
Published: March 2021

A study of the wave dynamics around a multiple cylindrical fishing cage system is carried out under the assumption of linear water wave theory and small-amplitude wave response. The Fourier–Bessel series expansion of the velocity potential is derived for the regions enclosed under the open-water and cage systems and the immediate vicinity. The scattering between the cages is accounted for by employing Graf's addition theorem. The porous flexible cage system is modeled using Darcy's law and the three-dimensional membrane equation. The edges of the cages are moored along their circumferences to balance its position. The unknown coefficients in the potentials are obtained by employing the matched eigenfunction method. In addition, the far-field scattering coefficients for the entire system are obtained by expanding the Bessel and Hankel functions in the plane wave representation form. Numerical results for the hydrodynamic forces, scattering coefficients, and power dissipation are investigated for various cage and wave parameters. The time simulation for the wave scattering from the cage system is investigated. The study reveals that wave loading on the cage system can be significantly reduced by the appropriate spatial arrangement, membrane tension, and porous-effect parameter. Moreover, the far-field results suggest that the cage system can also be used as a breakwater.
Machine-learning free-energy functionals using density profiles from simulations
Authors: Cats Peter , Kuipers Sander , de Wind Sacha , van Damme Robin , Coli Gabriele M. , Dijkstra Marjolein , van Roij René
Published: March 2021

The formally exact framework of equilibrium Density Functional Theory (DFT) is capable of simultaneously and consistently describing thermodynamic and structural properties of interacting many-body systems in arbitrary external potentials. In practice, however, DFT hinges on approximate (free-)energy functionals from which density profiles (and hence the thermodynamic potential) follow via an Euler–Lagrange equation. Here, we explore a relatively simple Machine-Learning (ML) approach to improve the standard mean-field approximation of the excess Helmholtz free-energy functional of a 3D Lennard-Jones system at a supercritical temperature. The learning set consists of density profiles from grand-canonical Monte Carlo simulations of this system at varying chemical potentials and external potentials in a planar geometry only. Using the DFT formalism, we nevertheless can extract not only very accurate 3D bulk equations of state but also radial distribution functions using the Percus test-particle method. Unfortunately, our ML approach did not provide very reliable Ornstein–Zernike direct correlation functions for small distances.
Structural chemistry of host – guest molecular architectures based on mercury-containing macrocycles
Authors: Dolgushin Fedor M. , Eremenko Igor L.
Published: March 2021

Metallomacrocycles that include several metal ions with the Lewis acid properties are peculiar antipodes of crown ethers (referred to as ‘anticrowns’ in the literature). Recently these architectures have been extensively investigated when searching for efficient and selective anion receptors. In this review, we analyze the data on the molecular and crystal structures of supramolecular complexes of mercury-containing macrocycles (hosts) with anions or neutral nucleophiles (guests). The emphasis is on the identification and systematization of the structure types of complexes in dependence of the guest molecule nature, as well as the macrocycle composition and structure. The factors affecting the selectivity of coordination and competitive ability of various electron donor moieties of guest molecules to binding to the macrocycle are considered. The data in the literature on the nonvalent host – guest and host – host interactions, which are responsible for the formation of molecular complexes and their supramolecular association in crystals, are analyzed. The formulated structural regularities of these coordination compounds with an unusual type of molecular architecture open ways to design directly promising molecular materials on their basis.

The bibliography includes 161 references.
State transitions among groups of cyclists in cycling points races
Authors: Okumura Fumihiro , Yokoyama Keiko , Yamamoto Yuji
Published: March 2021

This study analyzed the global state of groups formed by cyclists competing in three different points races and considered the behaviour of individual cyclists in those races. We measured the time difference between the front cyclist and the other cyclists when they crossed the centrelines of home and back straights in order to quantify the global configuration of cyclists in terms of their density and features of states, extracted using principal components analysis (PCA). We examined whether the group separation and group density that characterize the cycling race can be extracted by PCA. We interpreted the PCA results to explain the separation and density of the group using the first and second principal components. Then, we defined the state of configuration of the cyclists in each lap in the plane of the first and second principal components. Subsequently, the state transition probabilities were obtained. States 1, 2, 3, and 4 corresponded to the third, second, first, and fourth quadrants, respectively. State 1 represented a state comprising one dense group, state 2 represented one stretched group, state 3 represented a divided group, and state 4 represented an escape group far from a single dense group.

Highlights

An approach to understand the collective behaviour of cycling points races through principal component analysis was effective for quantifying the configuration of the cyclists.

Principal component analysis of the global configuration of the cyclists in the points races revealed the fission‐fusion dynamics was characterized by two components. The density of a group and number of groups, and transitions among four states was defined by these two components.

State transition probabilities indicate that the group separation states were more frequent in the latter half of the sprint interval, and it was difficult to re‐combine the separated groups into one.

The riders and coaches need to be aware of the stretching and separation of the group, even if it does not occur immediately before the sprint as the positioning of a cyclist in the group would be important at that time.
Mechanical apparatus for the fold catastrophe demonstration
Authors: Fiolhais M , Golli B , Nogueira R
Published: March 2021

We present and discuss a non-expensive mechanical experiment which is very suitable for a classroom demonstration of the fold catastrophe behaviour. The apparatus consists of a bar attached to a pulley, to which a hanging body is connected by means of a thread wrapped around its rim. The system may perform stable oscillations or, else, the body may continuously fall down, while the pulley executes a sequence of 360° rotations. This behaviour is analysed in connection with the shape of the potential, which is a good example of a fold catastrophe potential. For the system to perform stable oscillations, that shape reminds a clothes washboard, with local maxima and minima, a potential well known in superconducting quantum computing. We provide some hints for the instructor to explore the device in lab classes.
An original Pitot-static probe design for subsonic boundary layer investigation
Authors: Tescaroli E , Belan M
Published: March 2021

This work presents a Pitot-static probe designed and developed to help in some boundary layer (BL) measurements, as for instance when average velocity profiles are required around models already available for wind tunnel tests but not provided with static pressure taps. The probe reads both total and static pressures at the desired location and by traversing it through the BL leads to the desired velocity measurements on the body under test, without having to rebuild the model and without using more expensive and complicated techniques. The probe is presented by describing its geometry in detail and completing the information by the relevant operating instructions. The probe response is then characterized by reporting its directional sensitivity and a validation for a standard test case. The specific probe presented here is suitable for a certain range of BL thicknesses, however the design can be easily scaled to different ranges.
Enhanced dielectric and conductivity properties of carbon-coated SiC nanocomposites in the terahertz frequency range
Authors: Huang Feirong , Fan Shuting , Li Xiyang , Qu Xinghao , Tian Yuqi , Zhang Xuefeng , Zhang Zhidong , Dong Xinglong , Cao Tun
Published: March 2021

C-coated SiC nanocomposites (SiC@C NCs) were one-step synthesized under a mixture atmosphere of Ar and CH4 using a DC arc-discharge plasma method. The microstructure of the composites could be controlled by varying the volume ratio of Ar and CH4. A strong response to the terahertz (THz) field was observed due to the existence of a graphite shell. The dielectric properties of SiC@C NCs can be enhanced by altering the thickness of the graphite shell. The thicker graphite shell results in a stronger absorption of THz waves and an enhanced real part of conductivity. Fitting the measured conductivity data using the Drude–Smith model reveals that the carrier transport in the SiC@C NCs and its counterpart, the SiC nanoparticles, is dominated by backscattering. The SiC@C NCs with enhanced conductivity are believed to be fundamental materials for various functionalized optoelectronic devices.
Photocatalytic mechanism and performance of a novel wool flake–BiFeO3 nanosheet–TiO2 core–shell-structured composite photocatalyst
Authors: Chen Tianyu , Zhang Hui , Han Ye , Gu Haoshuai , Yang Limeng , Wu Hailiang , Mao Ningtao
Published: March 2021

In this study, BiFeO3 (BFO) nanosheets ground from BFO particles were first incorporated with wool flakes to construct sandwich-like wool–BFO composites using the vibration-assisted ball milling technique in freezing conditions. The wool–BFO composites were then loaded with a thick layer of TiO2 nanoparticles to prepare the core–shell-structured wool–BFO–TiO2 composites using a hydrothermal synthesis process. The microstructure of the core–shell wool–BFO–TiO2 composites and its photocatalytic applications were systematically examined using a series of characterization methods. Trapping experiments and electron spin resonance spectra were also employed to judge the active radical species like superoxide radicals (·O2
−), singlet oxygen (1O2), holes (h+), and hydroxyl radicals (·OH) using benzoquinone, furfuryl alcohol, ethylenediamine tetraacetic acid, and tert-butanol as the scavengers, respectively. The photodegradation performance of the wool–BFO–TiO2 composites was measured using more resistant methyl orange (MO) dye as the pollutant model. In comparison with the wool–TiO2 or wool–BFO composites, the superior photocatalytic properties of the wool–BFO–TiO2 composites under visible light irradiation were attributed to the presence of mesopores and macropores, the large specific surface area and intimate interface between wool–BFO composites and TiO2 nanoparticles, the coexistence of Fe3+, Fe2+, Bi3+, Bi(3–x)+, Ti4+, and Ti3+species, and the strong visible light harvesting, thus leading to the fast separation of photogenerated electron–hole pairs. The wool–BFO–TiO2 composites could be used for the repeated photodegradation of organic pollutants and be recycled easily using a magnet. The active radical species of the wool–BFO–TiO2 composites were ·O2
− and 1O2 rather than ·OH and h+, which were involved in the photodegradation of MO dye under visible light irradiation.
Preparation of single crystalline AlN thin films on ZnO nanostructures by atomic layer deposition at low temperature
Authors: Zhang Yuan , Tao Jia-Jia , Chen Hong-Yan , Lu Hong-Liang
Published: March 2021

The growth of hetero-epitaxial ZnO-AlN core–shell nanowires (NWs) and single crystalline AlN films on non-polar ZnO substrate at temperature of 380 °C by atomic layer deposition (ALD) was investigated. Structural characterization shows that the AlN shells have excellent single-crystal properties. The epitaxial relationship of [0002]ZnO//[0002]AlN, and [10−10]ZnO//[10−10]AlN between ZnO core and AlN shell has been obtained. The ZnO NW templates were subsequently removed by annealing treatment in forming gas, resulting in ordered arrays of AlN single-crystal nanotubes. The impact factors on the epitaxial growth of AlN films are thoroughly investigated. It turned out that the growth parameters including lattice mismatch between substrate and AlN, growth temperature, and the polarity of ZnO substrate play important roles on the growth of single-crystal AlN films by ALD. Finally, non-polar AlN films with single-crystalline structure have been successfully grown on m-plane ZnO (10−10) single-crystal substrates. The as-grown hollow AlN nanotubes arrays and non-polar AlN films with single-crystalline structures are suggested to be highly promising for applications in nanoscale devices. Our research has developed a potential method to obtain other inorganic nanostructures and films with single-crystalline structure at fairly low temperature.
Seeking missing pieces in learning about single slit diffraction: results from a teacher survey
Authors: Mešić Vanes , Škaljo Edvin , Mitrevski Boce , Nešić Ljubiša , Hatibović Senad , Maličević Mevludin
Published: March 2021

Single slit diffraction is part of many high-school physics curricula throughout the world. In this study, we aimed to investigate whether high-school physics teachers from Bosnia and Herzegovina, Serbia and North Macedonia are adequately prepared to discuss with their students about various aspects of the single slit diffraction pattern, particularly about vertical length of diffraction fringes. To that end we conducted a written survey which included 57 high-school physics teachers. Besides asking teachers about students’ difficulties in learning about single slit diffraction, we also asked them to specify their own difficulties with this topic and required them to solve a conceptual task. Almost every second teacher believed that vertical length of diffraction fringes can be increased by changing shape or width of the slit and only 1 out of 57 teachers managed to correctly answer why diffraction fringes become shorter when we move away from the central maximum. We concluded that physics teacher education programmes should be changed to develop understanding of both, horizontal and vertical aspects of the diffraction pattern. To that end it is useful to provide learning opportunities which encourage combining ray and wave model of light.
Pressure-driven stochastization of flux surfaces in stellarator equilibria: a review of the experimental observations and their analysis
Authors: Reiman Allan H
Published: March 2021

Stellarator vacuum fields are designed to have a dense set of nested flux surfaces, with only small islands and stochastic regions in the interior of the confinement region. As the plasma pressure is increased, pressure driven currents appear, and they can significantly modify the vacuum field. The question arises whether pressure driven currents can cause significant flux surface breakage. Both the Wendelstein 7-AS and large helical device stellarators had dedicated experimental campaigns to study the

β

limit in those devices. This paper reviews the evidence that the flux surfaces in a significant fraction of the plasma volume were stochastized by the pressure-driven currents in the highest

β

experiments. That phenomenon appears to have been the dominant source of pressure-driven flux surface loss in these experiments.
Unsteady effects at designing of modern aircraft jet engines
Authors: Kraev V M , Aslanov A R
Published: March 2021

The operating conditions of advanced aircraft engines powered by cryogenic fuel analyze in the paper. The authors demonstrate cryogenic fuel supply systems must be designed with transients’ processes consideration. These processes based on significant changes in heat exchange and hydrodynamics in unsteady conditions. Unsteady conditions result to dramatic up to 3 times and more growth of heat exchange coefficient and hydraulic resistance. The authors suggested a methods can be used for unsteady processes in cryogenic fuel system calculation.
Radiative and convective heat exchange in technological furnaces of petrochemical industry
Authors: Abdullin A M
Published: March 2021

Complex heat transfer in radiant chambers of technological furnaces of the petrochemical industry is considered. The object of research is a vertically located flat channel, approximately simulating a radiant chamber. The walls of the channel are formed by a refractory lining and a tubular screen with a known temperature. The chamber volume is filled with selectively emitting, absorbing and weakly scattering media of gaseous fuel combustion products. The research method is based on the numerical solution of two-dimensional integro-differential equations of radiation gas dynamics, closed by a two-parameter model of turbulent convection. The influence of the modes of organization of the combustion process, the radiation properties of the combustion products and refractory lining on the distribution of heat fluxes and the characteristics of the total heat transfer are considered.
Integrated researches of topical problems of fast reactors thermal physics
Authors: Sorokin A P , Kuzina Yu A , Alekseev V V , Grabezhnaya V A , Zagorulko Yu I , Kamaev A A , Orlov Yu I
Published: March 2021

The results of actual studies are presented to justify the thermophysical characteristics and safety of fast reactors with sodium and lead coolants. The influence of a stratified coolant flow on the formation of velocity and temperature fields in a fast reactor vessel with a sodium coolant is shown. The development of the degradation of the fuel assembly during the development of a severe accident with the loss of sodium flow rate in a fast reactor, the blockage of the cross sections of the fuel assembly and the release of marker materials beyond it are demonstrated. The expediency of the combined sodium purification system built into the reactor vessel is shown, in which “cold traps” are an indispensable element, and “hot traps” provide accelerated oxygen purification during operation of the NPP in nominal regime. The results of studies of a large-modular sodium-water steam are presented. As applied to a reactor with a lead coolant, the influence of spacer grids on heat transfer in a fuel assembly of the core is shown. On the model of the steam generator of the reactor installation with lead coolant, it was found that the values of the steam temperature at the outlet of both collectors coincide. The temperature of lead at the exit from the lowering section and in the main path of lead is coincides also. The state and prospects of the development of technology for heavy liquid metal coolants are analyzed. The principle possibility of providing the required parameters of a high-temperature fast reactor with a sodium coolant for the production of hydrogen is shown. The problems of further thermophysical research are analyzed.
Analysis of flow-field and heat exchange for a blunted cone at hypersonic speeds
Authors: Drozdov S M , Rtishcheva A S
Published: March 2021

The possibility of decoupled analysis of flow-field and heat transfer for a solid structure was investigated using numerical simulation of conjugate problem on hypersonic flow and heat transfer for a blunted cone made of heat-conducting material. The considered cones had semi vertex angle ϕ≈7 ° and two radii of blunting:

r

1

и

r

2

=

2

3

r

1

. This form is typical for noses of modern hypersonic aircraft. The ANSYS FLUENT software package was used to simulate a laminar flow with developed physicochemical models of nonequilibrium air (a five-component gas mixture was considered: O2; N2; O; N; NO) and S2S built-in model of radiative heat transfer. The accuracy of the decoupled analysis was evaluated as a result of comparison with the solution of the conjugate problem on flow-field and internal heat transfer.
Functional identification of transition processes in elements of the system of air heater-fan-room by the experimental results
Authors: Mansurov R Sh
Published: March 2021

The main energy-saving equipment used in the systems of providing of microclimate (SPM) are recuperative, regenerative heat exchangers and heat pump units (HPU). Of energy-saving technologies of air treatment possible to isolate the bypass of humidification chamber, first and second recycling of air, regulation of the flow rate of intake air depending on the contents of various hazards in the working zone air - heat, moisture, CO2, dust etc. To energy - saving modes of SPM include: normal operating mode; modes of intermittent heating, cooling and ventilation; modes of operation taking into account the assimilative capacity of the air volume and heat-accumulating properties of the enclosing structures of the room.

Combining energy-and resource-saving equipment, air treatment technologies into an integrated complex of technical solutions on a single platform, as well as the use of different modes of operation of the CPM will optimize energy and resource consumption to maintain the specified parameters of the microclimate in the room. Management of a single platform requires the development of an appropriate management system.

The basis for the creation of control systems is the knowledge of the transients occurring in the elements of SPM, and in the external environment. Since the main processes in the elements of SPM are the processes of thermal processing of air, for the construction of mathematical models requires knowledge about the laws of thermodynamic processes in the investigated elements of SPM. Identification in full-scale conditions achieves high accuracy and reliability of the developed mathematical models of transfer functions of elements of SPM. Experimental studies allow us to establish all the characteristics that determine the thermodynamic process in the element under study SPM.
Effect of packing factor and conductivity on heat transfer in reactor core domain with spherical fuel
Authors: Slyusarskiy K V , Larionov K B , Koothan V V
Published: March 2021

The effect of packing factor and conductivity on temperature distributions on the surface of the spherical fuel element in conditions of pebble bed nuclear reactor were studied 0.35by means of numerical simulation using Ansys Fluent. The body centred cubic geometry was applied. The packing factor was varied in range 0.1-0.35 while the conductivity was varied in range 1-100 W/(m K). The maximal and minimal surface temperatures were varied in ranges 695-900 and 680-780 K, respectively. The conductivity at 20 W/(m K) and above was found to had nearly no effect while the packing factor increasing resulted into nearly proportional decreasing of surface temperatures.
Determination of void fraction in a bed of solid particles by the method of flow cutoff
Authors: Tairov E A , Safarov A S
Published: March 2021

The paper presents a new method for determining the void fraction of two-phase flow with a condensable vapor phase. This method relies on the known technique of blocking the flow and allows measuring void fraction in the pore space of solid particle packings. The paper presents the results of experiments with packed beds of steel balls with diameters of 2 mm and 4 mm, 250 mm high. A comparison with some techniques for calculation of void fraction for empty vertical pipes is made.
Separation features of multicomponent gas mixtures at the border of regime change diffusion – concentration gravitational convection
Authors: Kossov V N , Fedorenko O V , Krasikov S A , Kalimov A B
Published: March 2021

The mixing of carbon dioxide dissolved in multicomponent gas mixtures at various pressures was studied. It was found that at a certain pressure the diffusion separation of components is violated and structured flows arise in the system. The pressure regions are fixed at which the conditions of priority transfer of the component with the highest molecular weight in the mixture are realized in the system. To analyze the effect of pressure on the process of changing the diffusion – convection modes, a mathematical model has been proposed that takes into account the kinetic features of multicomponent mixing. It is shown that the change in mass transfer modes is associated with a significant difference in the diffusion abilities of the components.