Theoretical Analysis Research Articles

Social solidarity of students: university practices and fashioning tools

The problem of the research. Integration and consolidation are needed in modern society. Of particular importance is the maintenance of solidaristic practices, the "education" of which should be carried out by the educational system in general and higher education institutions in particular. Today it is important to understand what tools the Russian university system has for the formation of solidaristic thought and action. In this regard, it is important to rethink the experience of the Soviet era, when solidarity education was part of the ideological system. The aim of the article is to identify the most effective tools and methodologies for fostering solidarity consciousness among students at Russian universities, with due consideration of both national and global experience. Materials and methods. Theoretical analysis was employed to examine Russian and global scientific literature on the nature and evolution of social solidarity among young people and students, its underlying principles and manifestations. The system approach and the principle of additionality were employed to comprehend the instruments and practices of social solidarity formation in higher education institutions. The position of an "internal observer" integrated within the university system was augmented and refined by the research position of an "external observer", enabling a comprehensive examination of the university system. Results. The system of Russian higher education in modern conditions continues to be the most important actor of socialization of the young generation, designed to instill in them one of the basic values – the value of social solidarity. The educational subjects within the social and humanitarian block, which form part of the overall educational process, have the potential to facilitate the formation of social solidarity. In order to fully grasp this concept, it is necessary to apply it to the ongoing process of updating the aforementioned disciplines, which are designed to create a uniform set of content and teaching methods. This will help to foster a holistic worldview in young people, equipping them to engage with the world around them in an informed and empathetic manner. The process of fostering solidarity thinking and action cannot be reduced solely to the educational process, the improvement of the curriculum and the set of disciplines. The trinity of educational, educational and scientific processes is capable of forming social solidarity among modern Russian students. Conclusion. It is challenging to envisage Russian society without the pivotal role of higher education, which is tasked with actively shaping the value priorities of young people. In light of the crucial mission of socialization carried out by higher education institutions, which includes the formation of fundamental values and the promotion of solidarity practices among student youth, it is evident that the influence of higher education on the younger generation of Russian citizens is significant.

Microplastic fragmentation into nanoplastics by water shear forces during wastewater treatment: mechanical insights and theoretical analysis

Microplastic fragmentation into nanoplastics by water shear forces during wastewater treatment: mechanical insights and theoretical analysis

Electronic and transport properties of Ti3C2O2-based strain sensor: A DFT-NEGF study

MXenes used as strain sensing materials have recently roused extensive interest due to their two-dimensional structures and outstanding electric properties. However, theoretical analysis from a quantum perspective is relatively scarce, which may hinder the development of this emerging field. Based on density functional theory with non-equilibrium Green’s function, we explored the structure, electronic, and transport properties of Ti3C2O2 with and without biaxial strains. The Ti3C2O2 monolayer remained stable under 5% biaxial strain. The structures and electronic properties of Ti3C2O2 showed gradual evolutions tuned by strain. Moreover, we studied the intrinsic device properties by constructing two-probe devices. The current of the 5% biaxially strained device increased by about 80% compared with the unstrained device. Given the results mentioned earlier, the Ti3C2O2-based nanodevices have the prospect of being strain sensors.

A novel time-current-temperature difference (T-I-T) defrosting control method for air source heat pump based on outdoor fan operation characteristics in space heating

In space heating, air source heat pumps (ASHPs) always encounter mal-defrosting incidents, resulting in significant energy waste. To improve the defrosting accuracy of ASHP, this paper proposes a novel Time-Current-Temperature difference (T-I-T) defrosting control method based on the characteristic parameter of outdoor fan operation (current). Through theoretical analysis and experimental tests, the influence of frosting on the characteristic parameters of outdoor fan operation was revealed. Then, based on the optimal defrosting control point theory, a method for selecting the defrosting current threshold close to the actual ASHP was proposed. Ultimately, a novel Time-Current-Temperature Difference (T-I-T) defrosting control method was developed, using the current increment to control the defrosting operation. The results showed that, the defrosting current thresholds decreased as the severity of frosting decreases, from 1.52 to 0.78 A. The T-I-T defrosting control method enables the ASHP unit to operate stably and efficiently in space heating. The defrosting frequency decreased from 0.93 to 0.56 times per hour, a reduction of 39.80 %; the average duration of the frosting/defrosting cycle increases from 64.30 to 106.90 min (an increase of 66.25 %), and the average COP of the ASHP unit increases by 10.60 % compared to the T-T defrosting control method.

Effects of residual stress on the isothermal tensile behavior of nanocrystalline superelastic NiTi shape memory alloy

The residual stress greatly affects the mechanical behavior of a material. In this work, the effect of residual stress on the isothermal tensile behavior of a NiTi shape memory alloy is studied. The focused ion beam and digital image correlation are combined to measure the two-dimensional residual stress in nanocrystalline NiTi plates processed with prestrain laser shock peening. A four-point bending experiment verified the accuracy of this measurement method. The FIB-DIC method is an attractive tool for measuring the two-dimensional residual stress in phase transition nanocrystalline materials. The internal residual stress significantly decreases the phase transition stress, and the mechanism is studied via finite element and theoretical analyses. This work implies that the mechanical behavior of NiTi shape memory alloys can be tailored via residual stress engineering.

Інноваційні методологічні підходи до оцінки психофізичних здібностей гандболістів на етапі попередньої базової підготовки

The article deals with the psychophysical abilities of young handball players at the stage of preliminary basic training. Particular attention is paid to the analysis of the level of formation of such abilities as reaction speed, coordination of movements, concentration of attention and the ability to make decisions in stressful situations. The scientific relevance of the study is due to the need to improve training methods aimed at increasing the effectiveness of athletes' preparation for competitions. The purpose of the study is to analyze and evaluate the psychophysical abilities of young handball players, which will help to determine the effectiveness of the applied training methods and contribute to the development of new approaches to the training of athletes. Material and methods of research. Handball players at the stage of preliminary basic training (103 people) at the age of 15-16 years old, involved in the championship of Ukraine among boys, took part in the pedagogical experiment. To implement the goals and objectives of the study used a set of methods: theoretical analysis, synthesis and generalization; pedagogical observation; pedagogical testing; mathematical and statistical data processing. Research Results. It was found that the psychophysical abilities of young handball players who are at the stage of preliminary basic training correspond to a satisfactory level. However, in order to achieve high results in the future it is necessary to improve training programs taking into account the individual characteristics of each athlete. Analysis of the test results showed that the majority of handball players, both from the experimental and control groups, demonstrate similar results on the complex index of psychophysical abilities, which allowed us to conclude that there were no significant differences in the levels of development of psychophysical abilities between the groups at the beginning of the study. It was revealed that the average characteristics of different psychophysical tests in the majority of athletes correspond to a satisfactory level. For example, the speed of reaction to visual stimuli, reaction speed in game conditions, as well as the results of specialized handball tests showed that the level of formation of these abilities is sufficient for participation in competitions, but requires improvement to achieve high results. It is important to note that the highest average values of complex indicators of psychophysical abilities were observed in point guard players, which corresponds to the average level of formation. Line players also showed the results corresponding to the average level, while half-middle and edge players showed slightly lower values corresponding to the satisfactory level. Conclusions. The conducted study showed that at the stage of preliminary basic training most young handball players have a satisfactory level of development of psychophysical abilities, which indicates that there is a potential to improve their sports training by improving training methods. Given that different players demonstrate different levels of development of psychophysical abilities, especially among midfield and edge players, it is necessary to develop and implement individual training programs, which will optimize the training of each player in accordance with his individual characteristics and increase the overall effectiveness of the team.

Determination and analysis of compensation capacitor for a robust distance-variable wireless power transfer system

Wireless power transfer (WPT) systems have been widely adopted for full autonomy in various fields due to their convenience. However, changes in the air gap between the Tx and Rx coils significantly affect efficiency. To overcome this challenge, this paper introduces the determination of a compensation capacitor for a distance-variable WPT system that is robust in varying air gap conditions. The proposed method was verified using theoretical analysis, simulation, and experimental measurement. The electrical circuit was modeled using a T-equivalent model in a series–series (SS) topology to calculate power transfer efficiency (PTE). Specifically, compensation capacitors were analyzed at distances of 10, 30, and 50 mm, considering different self-inductance values. These results are compared against varying load resistances to demonstrate the effectiveness of the proposed approach. Additionally, the PTE drop ratio was defined to facilitate comparison. The results show that the PTE drop ratio for the compensation capacitor at the farthest distance was consistently smaller than that for the capacitor at the nearest distance under varying air gaps and load resistances. In this research, the difference in the PTE drop ratio between 10 and 50 mm was measured, demonstrating that determining the capacitor at the farthest distance reduces the PTE drop ratio across a range of operational conditions.

Numerical study of internal solitary wave loads on a submerged slender body with multi-parameter coupling

This study investigates the destabilizing loads exerted on submarines by large-amplitude internal solitary waves (ISWs), which significantly increase the risk of a phenomenon known as “falling deep.” Using numerical simulations and theoretical analysis, the research explores the multi-parameter coupling effects of ISWs on a slender body in a two-layer fluid system. A numerical wave generation method for large-amplitude ISWs, based on the strongly nonlinear adjusted high-order unidirectional (aHOU) model, is proposed. A corresponding numerical model is also developed to simulate the interaction between ISWs and a submerged slender body, with validation against experimental data confirming its accuracy and reliability. The study further examines how wave amplitude, submergence depth, and wave incidence angle affect the load characteristics induced by ISWs. Theoretical analysis identifies the components of ISW-induced loads, revealing a linear relationship between horizontal load and wave amplitude, as well as the influence of submergence depth on the duration of vertical forces. The primary contributor to the horizontal force is identified as the pressure-gradient force generated by the ISW's flow field, while the vertical force is primarily driven by the reduced gravity force due to density stratification and wave forces, which are well-approximated by Morison's formula. Additionally, the peak values of horizontal and vertical forces are significantly affected by wave incidence angle and wave amplitude, respectively. These findings provide a theoretical foundation for understanding the “falling deep” phenomenon encountered by submarines under the influence of ISWs.

Influence of steam curing on cyclic triaxial characteristics of recycled aggregate concrete: Experimental analysis and DEM simulation

The engineering application of steam-cured recycled aggregate concrete (often in a cyclic triaxial stress state) can not only improve the recycling efficiency of resources, but also accelerate the construction progress. In this paper, we adopt a combination of laboratory experiments, theoretical analysis and numerical simulation to study the cyclic triaxial characteristics of recycled aggregate concrete (RAC) under different curing regimes (20℃, 40℃, 60℃ and 80℃). The results indicate that as the steam curing temperature increases, the internal damage caused by high temperature continues to intensify, and the cyclic triaxial failure mode of RAC transitions from shear failure to compression failure, and its peak strength, dynamic elastic modulus, and dilatancy angle all show a downward trend. A linear prediction model is established based on the strong correlation between peak strength and steam curing temperature. As the loading cycles increase, the dynamic elastic modulus and dilatancy angle of RAC show exponential and linear downward trends respectively, and the decline rate increases with the increase of steam curing temperature, and the prediction models for dynamic elastic modulus and dilatancy angle are established based on quantitative relationships between variables. On the basis of experimental analysis results, a cyclic triaxial DEM model considering real recycled aggregates is established by introducing steam-cured damage indexes into the mesoscopic parameters, and its applicability in predicting cyclic triaxial mechanical properties of RAC under different curing regimes is verified. The research outcomes can save a lot of test cost and time consumption for developing steam-cured concrete with better performance, and have important theoretical guidance and practical significance for the wide application of steam-cured concrete.

Soft Switching Technique in a Modified SEPIC Converter with MPPT using Cuckoo Search Algorithm

: MPPT refers to the process of continuously tracking and adjusting the operating point of a photovoltaic (PV) system to maximize the power output from the solar panels. The operating point at which a PV system produces the most power under a specific set of environmental circumstances is known as the maximum power point (MPP). The Maximum power point tracking (MPPT) technique is used to overcome the challenges of PV arrays with variable irradiance levels, which collects the greatest power from the PV array. Standalone PV systems, as well as gridconnected systems, can benefit from a DC-DC converter with MPPT. This study compares the standard perturbation and observation (P&O) technique with the soft-switching method used in the SEPIC converter utilizing the cuckoo search (CS) algorithm using MATLAB/Simulink. Reviewing the simulation results and assessing the SEPIC converter's performance. Background: SEPIC soft-switching converter, the soft-switching technique is applied to the SEPIC converter topology. It typically uses additional components, such as inductor and capacitors, to enable soft-switching operation. These additional components help to control the voltage and current waveforms across the main switching devices, reducing switching losses. Methods: The proposed method uses a soft switching technique to reduce switching losses and to improve efficiency. Soft switching is used in SEPIC (Single Ended Primary Inductor Converter) converters, a type of DC-DC converter, to enhance their performance. The projected solution further addresses the maximum power point tracking (MPPT) issue in PV systems using the Cuckoo Search (CS) method. Results: Soft switching technique is implemented in SEPIC converters to reduce these switching losses. In this system, Zero Voltage Switching (ZVS) involves turning on the switch when the voltage across it is zero. This allows the current to flow through the switch without creating any significant switching losses. CS algorithm can track the MPP quickly and accurately, it exhibits less prone to oscillations, easily monitor the MPP under a variety of weather circumstances. However, it exhibits negligible oscillation in a steady state, which results in significant power savings. Conclusion: The modified SEPIC converter with a soft-switching MPPT cuckoo algorithm is used with a solar-powered system. A prototype comprising a solar panel, a SEPIC converter, a driver, and a controller circuit was created. A soft-switching SEPIC converter with an MPPT cuckoo algorithm for the PV system is implemented, as are the converter operation, converter analysis, and theoretical analysis, and a controller circuit is analysed. The PV system, MPPT controller with tracking algorithm, and PMSM load were used in the system simulation. A 60-watt SEPIC converter prototype is built, and the outcomes are also tested experimentally.

Electromagnetic radiation of granite under dynamic compression

To elucidate the characteristics and mechanism of electromagnetic radiation in granite under impact loading, based on the quasi-static compression tests, this paper conducts dynamic compression experiments on granite using Hopkinson pressure bar and one-stage light-gas gun as loading methods. Combined with experimental and theoretical analyses, the relationship between mechanical and electromagnetic responses under impact loads of different intensities, and the time-domain signals of electromagnetic radiation generated by a single crack under different strain rates are studied. The intensity and frequency of electromagnetic radiation increase with the increasing compressive strain rate. According to the thermal activation theory, it reveals the microscopic mechanism of the transition from intergranular microcracks to transgranular microcracks in terms of strain sensitivity. It also serves as the physical basis for the increase in electromagnetic radiation intensity amplitude and frequency with increasing compressive strain rate. Transgranular microcracks are the primary cause of electromagnetic radiation generated by fractures.

A study on the reduction of high-temperature in the high-pressure piping system of civil aircraft

Abstract For the study of the bleed air flow process in high-pressure pipelines, theoretical analysis and numerical simulation were used to investigate the temperature drop problem in the pipelines. The effect of bleed air and ambient temperatures on the performance of temperature drop in high-pressure pipelines was discussed in detail. The performance of pipeline insulation before and after applying the insulation layer was also discussed. The results show that the higher bleed air temperature and lower ambient temperature obviously cause a greater drop in the bleed air temperature drop. The entrance section of the pipeline is approximately five times the l/d range. Applying the insulation layer can effectively reduce the drop in pipeline temperature. Generally, the air insulation layer can reduce the temperature drop of high-pressure pipeline gas by 25%. If further reduction is required, the vacuum insulation layer can be applied.

Optoelectronic and photoacoustic waves in rotating excited semiconductor subjected to thermal shock

In this study, the impact of rotation on the transmission of optical acoustic waves, arising from the movement of the optical carrier within an elastic thermal environment, is examined through theoretical analysis. The theoretical framework incorporates the interaction between acoustic waves and thermomechanics to formulate governing equations specific to a semiconductor medium. The fundamental equations of the physical model, influenced by photothermal and thermoelastic principles, are deduced mathematically while considering the presence of rotation. The model studied the medium under a thermal shock wave from thermal stress resulting from light-induced temperature elevation that is not fixed but decaying over time. The mathematical model is solvable using the normal mode method. The model’s numerical solutions provide access to all physical fields within the physical domain, encompassing displacement, temperature, acoustic pressure, mechanical stress, and carrier density diffusion. Utilizing the harmonic wave method, a two-dimensional graphical representation of the rotation parameter with and without the influence of the decay parameter is obtained. The theoretical analysis involves comparison, analysis, and discussion of the effects of these parameters investigated.

Theoretical analysis of organic Rankine cycle for maximum power generation in optimization operation conditions

The global critical issue in energy scarcity should be appropriately solved to realize a sustainable society. Effective use of Rankine cycle is one possible way since it provides most of worldwide electricity production. In this paper, theoretical analysis model of organic working fluids R717, R134a, R1234yf, R290, R245fa and R1233zd in Rankine cycle for maximum power generation in optimization operation using low-temperature heat sources are proposed and studied for development next generation green and zero-carbon energy generation system to promote the race to zero. Results show that temperatures of warm and cold water at inlet, mass flow rate of the warm water and performance of the evaporator play a key role to obtain the theoretical optimization operation conditions for maximum power generation. In the case of same initial conditions of temperatures of warm water (85 Celsius degree) and cold water (15 Celsius degree) at inlet, mass flow rate of the warm water (10kg/s) and performance of the evaporator (100kW/K), R717 has the best performance in terms of the maximum power output 56.0kW with thermal efficiency of 8.6%, and the next is the R1233zd (54.4kW, 8.3%), R245fa (54.0kW, 8.2%), R134a (52.8kW, 7.9%), R290 (52.7kW, 7.9%), and R1234yf (51.7kW, 7.7%). Here, it should be noticed that other optimization conditions are almost the same (mass flow rate of the cold water 9.1∼9.2kg/s; performance of the condenser 91∼92kW/K) to get their maximum power output of ORC. In addition, it also known that low-GWP R1233zd (GWP: 1) can deserve the best option to replace R245fa (GWP: 950) and R1234yf (GWP: 4) also can replace r134a (GWP: 1430) since their optimization operation conditions are almost same.

Evolutionary dynamic of the coupled awareness-epidemic networks with higher-order structure

Mitigating epidemic spreading and outbreaks is crucial to reducing their significant impacts on people’s lives. Although research has begun to consider the impact of information networks on disease transmission in recent years, most studies have not fully considered the high-order characteristics in network structures. To better capture the dynamics of epidemic spreading and comprehensively understand and predict epidemic transmission patterns, a model of epidemic spreading in a coupled awareness-epidemic model, considering higher-order structures, is proposed. Extensive simulations on real and synthetic structured networks show that information networks influence the spread on physical contact networks by altering individual behaviors, leading to a transition from bistability to a single stable state induced by higher-order structures. Through theoretical analysis, it is proved that the corresponding conclusion is that as the information influence value (an indicator that measures the impact of information networks on physical contact networks) decreases, the impact of higher-order structures on the system’s dynamic behavior gradually weakens. This leads to the disappearance of the bistable phenomenon originally caused by the presence of higher-order structures, and the system transitions from a bistable state to a single stable state. This transition is accompanied by an increase in the threshold for epidemic outbreaks and a decrease in the stable infection density. This work contributes to a deeper understanding of the influence of information on epidemic dynamics, providing important theoretical guidance for the future development of more effective prevention and control strategies.

Mechanical properties and constitutive model of deep marble under alternating creep-fatigue action

Given the time dependence and susceptibility to disturbance of deep rocks, this paper analyzes mechanical properties, acoustic emission (AE) signals, and pore radius distribution characteristics of deep marble under alternating creep-fatigue (ACF) action at different confining pressures by experiment and theoretical analysis. The results show that: (1) the alternation of creep and fatigue accelerates the rock damage, and the number of alternations increases with the increasing confining pressure. (2) Strain increments exhibit a pattern of first decreasing and then increasing, and they undergo a transformation from “V”-type to “U”-type with the increase of confining pressure. (3) The AE ringing count is mainly generated in the fatigue segment. The radius of large pores inside the rock is constrained by the confining pressure. (4) The ACF constitutive model is established, where model parameters show a nonlinear decreasing trend of the power exponential function with the strain increment.

Systematical Sensor Path Optimization Solutions for AOA Target Localization Accuracy Improvement With Theoretical Analysis

Systematical Sensor Path Optimization Solutions for AOA Target Localization Accuracy Improvement With Theoretical Analysis

Does economic policy uncertainty matter to corporate default probability? findings from theoretic analyses and China’s listed firms

Does economic policy uncertainty matter to corporate default probability? findings from theoretic analyses and China’s listed firms

Проблема футбольного інтелекту у сучасних дослідженнях

Speed, dynamism, high physical and mental loads characterize modern soccer. In this regard, the player's intelligence plays an important role during the game, because it: affects the form of tactical behavior; allows to make effective decisions in stressful situations; increases the player's ability to understand and establish links between game episodes and solve problematic game episodes using available tactical information. Therefore, the study of theoretical, tactical and psychological aspects of the development of intellectual abilities of a player is important for obtaining high results in this sport. The aim of the study is to analyze theoretical research on the peculiarities and development of intellectual abilities of soccer players. Research methods: theoretical analysis and generalization of scientific and methodological literature. Research results. As a result of the conducted analysis of literary sources it was determined that soccer intelligence is a way of thinking that allows a player to solve problem situations using knowledge, experience, skills and natural data, which are best suited for a particular game situation. Player's intelligence is a complex multilevel structure that is the result of player's adaptation to the conditions of the game space, constitutes a special form of tactical behavior of the player, is the result of purposeful tactical training of the player as a set of elementary processes of information processing and a system of cognitive processes. Conclusions. In soccer, the intellectual component is an integral part of both the game itself and the training process. Coaches are interested in its improvement and effective use because soccer intelligence is a way of thinking that allows a player to successfully solve problem situations using knowledge, experience, skills, and natural data that are best suited for a particular game situation.

Automatic construction and verification algorithm for smart contracts based on formal verification

As an emerging technology, blockchain demonstrates strong potential for applications in digital finance. As a core component of blockchain, the security and reliability of smart contracts is crucial. To ensure the high reliability of smart contracts, this study employs formal construction and verification techniques based on game theory. Initially, the profit function is defined using distortion techniques, and a game model for supply chain participation is designed. However, the equilibrium solution of the two-party game does not represent the optimal solution for the supply chain system. Therefore, the study introduces third-party participation to optimize the equilibrium solution. Finally, a probability model detection method is used to verify the constructed smart contract model. The results show that the supply chain model, analyzed through formal methods, has attributes consistent with theoretical analysis. Consequently, the research on automatic construction and verification algorithms for smart contracts based on formal verification proves to be effective and feasible in practical applications.