Constant Change Research Articles

Composite phase change materials with thermal-flexible and efficient photothermal conversion properties for solar thermal management

Composite phase change material (CPCM) with the advantages of high enthalpy and constant temperature phase change, has been widely used in many fields, such as photovoltaic thermal system, building envelope structure and so on. However, conventional CPCM is often rigid, poor light absorption and low thermal conductivity, which limits the application of solar energy utilization. In this paper, a novel Paraffin wax/Thermoplastic elastomer/Carbon nanotube(PA/SEBS/CNT) with shape stability, thermos-flexibility and high photothermal conversion efficiency was prepared, PA as the phase change material, SEBS as the flexible material and CNT as the light-absorbing material. The results show that the addition of CNT increases the absorbance of PA/SEBS from 0.3 to 1.0, and the photothermal conversion efficiency of PA/SEBS/CNT-10 % is as high as 96.17 %. In addition, the CPCM also has a high enthalpy value of 180 J/g, and a high thermal conductivity of >0.3403 W/(m·K), and also exhibits shape-driven memory. At the same time, outdoor photothermal experiments show that PA/SEBS/CNT has excellent photothermal conversion performance under real sunlight, and the highest temperature can reach 99.51 °C. The new CPCM developed has a broad application prospect in solar thermal systems.

Sulfate reduction behavior in response to landfill dynamic pressure changes

During the long-term stabilization process of landfills, the pressure field undergoes constant changes. This study constructed dynamic pressure changes scenarios of high-pressure differentials (0.6 MPa) and low-pressure differentials (0.2 MPa) in the landfill pressure field at 25 °C and 50 °C, and investigated the sulfate reduction behavior in response to landfill dynamic pressure changes. The results showed that the pressurization or depressurization of high-pressure differentials caused more significant differences in sulfate reduction behavior than that of low-pressure differentials. The lowest hydrogen sulfide (H2S) release peak concentration under pressurization was only 29.67% of that under initial pressure condition; under depressurization, the highest peak concentration of H2S was up to 21,828 mg m−3, posing a serious risk of H2S pollution. Microbial community and correlation analysis showed that pressure had a negative impact on the sulfate-reducing bacteria (SRB) community, and the SRB community adjusted its structure to adapt to pressure changes. Specific SRBs were further enriched with pressure changes. Differential H2S release behavior under pressure changes in the 25 °C pressure environments were mediated by Desulfofarcimen (ASV343) and Desulfosporosinus (ASV1336), while Candidatus Desulforudis (ASV24) and Desulfohalotomaculum (ASV94) played a key role at 50 °C. This study is helpful in the formulation of control strategies for the source of odor pollution in landfills.

Study of dynamical behaviors of harvested stage-structured predator–prey fishery model with fear effect on prey under interval uncertainty

The lack of clarity in many parameters used in ecological models is due to the constant changes in nature. The fundamental predator–prey model discussed in this article takes into account several ecological parameters as parametric-functional interval numbers. It discusses the dynamic characteristics of the model within the context of an uncertain environment. To account for this uncertainty, the model incorporates the concepts of bionomic equilibria and maximum sustainable yield (MSY). The article explores the optimal harvesting policy by applying Pontryagin’s maximum principle in an imprecise and uncertain environment. The proposed imprecise model formulation includes two additional variables: the influence of fear on prey population growth rate and the harvesting of prey and juvenile predator populations. The system of interval differential equations governs the interactions between these imprecise species, allowing for mathematical analysis of the proposed system. The aim of this study is to evaluate the robustness of an imprecise prey–predator model within an unpredictable environment. The article concludes by presenting rigorous numerical simulations that support all the analytical findings.

Resonance Enhancement of Vibrational Polariton Chemistry Obtained from the Mixed Quantum-Classical Dynamics Simulations.

We applied a variety of mixed quantum-classical (MQC) approaches to simulate the VSC-influenced reaction rate constant. All of these MQC simulations treat the key vibrational levels associated with the reaction coordinate in the quantum subsystem (as quantum states), whereas all other degrees of freedom (DOFs) are treated inside the classical subsystem. We find that, as long as we have the quantum state descriptions for the vibrational DOFs, one can correctly describe the VSC resonance condition when the cavity frequency matches the bond vibrational frequency. This correct resonance behavior can be obtained regardless of the detailed MQC methods that one uses. The results suggest that the MQC approaches can generate semiquantitative agreement with the exact results for rate constant changes when changing the cavity frequency, the light-matter coupling strength, or the cavity lifetime. The finding of this work suggests that one can use computationally economic MQC approaches to explore the collective coupling scenario when many molecules are collectively coupled to many cavity modes in the future.

Principle and method of deception systems synthesizing for malware and computer attacks detection

The number of different types and the actual number of malware and computer attacks is constantly increasing. Therefore, detecting and counteracting malware and computer attacks remains a pressing issue. Users of corporate networks suffer the greatest damage. Many effective tools of various kinds have been developed to detect and counteract these effects. However, the dynamism in the development of new malware and the diversity of computer attacks encourage detection and countermeasure developers to constantly improve their tools and create new ones. The object of research in this paper is deception systems. The task of this study is to develop the elements of the theory and practice of creating such systems. Deception systems occupy a special place among the means of detecting and counteracting malware and computer attacks. These systems confuse attackers, but they also require constant changes and updates, as the peculiarities of their functioning become known over time. Therefore, the problem of creating deception systems whose functioning would remain incomprehensible to attackers is relevant. To solve this problem, we propose a new principle for the synthesis of such systems. Because the formation of such systems will be based on computer stations of a corporate network, the system is positioned as a multi-computer system. The system proposes the use of combined baits and traps to create false attack targets. All components of such a system form a shadow computer network. This study develops a principle for synthesizing multi-computer systems with combined baits and traps and a decision-making controller for detecting and countering IEDs and spacecraft. The principle is based on the presence of a controller for decisions made in the system and the use of specialized functionality for detection and counteraction. According to the developed principle of synthesizing such systems, this paper identifies a subset of systems with deception technologies that must have a controller and specialized functionality. The decision-making controller in the system is separate from the decision-making center. Its task is to choose the options for the next steps of the system, which are formed in the center of the system, depending on the recurrence of events. Moreover, prolonged recurrence of external events requires the system center to form a sequence of next steps. If they are repeated, the attacker has the opportunity to study the functioning of the system. The controller in the system chooses different answers from different possible answers for the same repeated suspicious events. Thus, an attacker, when investigating a corporate network, receives different answers to the same queries. Specialized functionality, in accordance with the principle of synthesis of such systems, is implemented in the system architecture. It affects the change of system architecture in the process of its functioning as a result of internal and external influences. This paper also considers a possible variant of the architecture of such deception systems, in particular, the architecture of a system with partial centralization. To synthesize such systems, a new method for synthesizing partially centralized systems for detecting malware in computer environments has been developed based on analytical expressions that determine the security state of such systems and their components. In addition, the experiments showed that the loss of 10-20% of the components does not affect the performance of the task. The results of the experiments were processed using ROC analysis and the algorithm for constructing the ROC curve. The results of the experiments made it possible to determine the degree of degradation of the systems constructed in this manner. Conclusions. This paper presents a new principle for the synthesis of multi-computer systems with combined decoys and traps and a decision-making controller for detecting and counteracting IEDs and spacecraft, as well as methods for synthesizing partially centralized systems for detecting malware in computer networks.

Shift manipulation of intrinsic localized mode in ac driven Klein Gordon lattice

Shift manipulation of intrinsic localized mode (ILM) is numerically discussed in an ac driven Klein Gordon lattice. Before the manipulation, we introduce the 2-degree of freedom nonlinear system, which is obtained by reducing the lattice. In the reduced system, two localized modes correspond to ILMs in the original system. These two localized modes are switched by changing a coupling constant adiabatically. Based on the result obtained in the reduced system, we numerically show that the shift manipulation of ILM is achieved, like a particle, by using an adiabatic change of coupling constant between the targeted sites in the lattice.

STUDY OF A DISTRICT HEATING SYSTEM WATER BOILER AS A OBJECT OF CONTROL


 
 The analysis of the operating conditions of a typical district heating system, in particular, a hot water gas boiler, was carried out. It is shown that the boiler, as the main control object, operates under conditions of constant change in external heat load, which, due to their random nature, leads to a number of uncertainties. The expediency of the mathematical description of uncertainties using the stochastic method as the most tested in practical conditions is substantiated. According to the results of the passive experiment on the hot water gas boiler KVG6.5-150 of the district heating system of one of the districts of Kharkov, an array of hourly experimental data was obtained, reflecting the main performance indicators of the hot water boiler. As a result of data processing by the least squares method, a mathematical model of the boiler was obtained in the form of a linear regression equation, reflecting the relationship between the temperature of the coolant at the boiler outlet and the ambient air temperature, the temperature of the coolant at the inlet to the boiler and with the flow rates of natural gas and coolant to the boiler. The obtained regression equation was verified by Student's t-test, which confirmed the significance of all coefficients of the regression model. The practical significance of the multiple regression equation was assessed using the coefficient of determination. The quality of the multiple regression equation as a whole was assessed using Fisher's F-test. Since parallel surveys were not conducted, instead of checking the adequacy, the quality of the approximation of the experimental points by the accepted regression equation was assessed, that is, it was checked whether this equation makes sense. Such a test was carried out by comparing the residual variance and the variance relative to the mean. The calculation results showed that the value of the coefficient of determination significantly exceeds the allowable value, and the actual value of the Fisher criterion significantly exceeds the table value. The obtained indicators led to the conclusion that the relationship between the variables in the regression model is significant, and the proposed stochastic method and the multiple linear regression equation can be used to make decisions in the process of synthesizing the technical structure of a computer-integrated control system for objects of a district heating system.
 
 
 
 
 

ТРАНСФОРМАЦИЯ ДЕЯТЕЛЬНОСТИ ЦЕНТРОВ КАРЬЕРЫ РОССИЙСКИХ ВУЗОВ В СОВРЕМЕННЫХ УСЛОВИЯХ

The paper addresses the urgent problem of graduate employment in the context of labor market transformation. Having considered the main directions of activities of career centers of Russian universities, the authors of the article dwell on the analysis of the peculiarities of the activities of career centers of universities. The study shows that, despite the diversity of approaches to the organization of career centers’ activities, in the conditions of constant changes and challenges of the labor market, the formation of a graduate’s employability is of particular importance in the development of his/her career.

Western life courses challenged in life stories collected in contemporary China.

The life course describes the progression of life as a social role, from birth to death. Traditional Western life-history studies of the life course usually describe a continuous lifeline with occasional interruptions in between. The extraordinary temporal events of the Anti-Japanese War (AJW), Civil War (CW), Great Famine (GF), Cultural Revolution (CR), and the Reform and Opening-up of China in just few decades mean that the life history of contemporary Chinese older adults may be quite different from those of their western peers. The study used qualitative research methods to conduct in-depth interviews with 16 older adults and collect their life stories through a standardized list of questions. Grounded theory was employed to condense, compare, conceptualize, and synthesize patterns within the collected data, approaching the investigation with a "naturalistic" perspective. Based on a generalized analysis of the Interview transcripts, we can find that Chinese old adults' life stories were shaped by recurring exceptional and rapidly changing environmental conditions. The themes and sub-themes of Chinese old adults' life stories were focus on (1) violence, loss of family member, escape and unstable life in their early life which are related to AJW and CW; (2) poverty and starvation in daily life when they were adolescents and young adults which are related to GF; (3) discontinuity, timed opportunities, categorizations in order to split the social relationships and networks in CR. The data also suggest that education is an important part of the life story and that its value changes over time. The discontinuity and instability of the life stories of the Chinese old adults are unexpected according to the dominant Western-influenced life course theories, which enriches life course theory and provides a new perspective for studying the individual life course in a society of constant and rapid change.

CONCEPTUAL PROVISIONS REGARDING THE DEFINITION OF THE DEVELOPMENT OF CONSTRUCTION ENTERPRISES

It has been determined that the development of construction enterprises is influenced by a combination of internal and external factors that form negative trends in their functioning. In particular, a decrease in the volume of production and sale of construction products, a reduction in the level of their investment attractiveness, and a slowdown in the growth of production and economic potential have been identified. At the same time, it has been proven that construction enterprises act as an indicator of the development of a state’s economy and characterise the directions and features of its functioning. Thus, the research topic is relevant, and its development is timely. The purpose of the study is to define the development of construction enterprises. To achieve this goal, we need to solve the following tasks: to identify the directions of the development of enterprises, to systematise theoretical provisions regarding the definition of the development of enterprises, and to single out the specific features of the development of construction enterprises. As a result of the study, theoretical provisions regarding the definition of the development of construction enterprises were systematised, and the author’s approach to its characterisation was proposed. The conceptual apparatus of economic science has been improved; in particular, the concept of the “development of construction enterprises” has been introduced into the functional field of effective management of enterprises. Unlike the existing ones, it is determined by constant changes in the system of forming strategic and operational directions for the creation and use of all types of resources, organisational structure, and production and economic potential of construction enterprises, which allows ensuring the effectiveness of stakeholder interaction, marketing activities, growth of financial, economic, investment, innovation, and strategic factors. The study has revealed the specific features of the functioning of construction enterprises in extraordinary economic conditions of the influence of internal and external factors and the consequences of the aggression of the Russian Federation. Keywords: construction enterprises, stakeholders, development, conceptual provisions.

Non-supersymmetric AdS from string theory

We construct non-supersymmetric AdS_3AdS3 solutions of the \mathrm O(16)× \mathrm O(16)O(16)×O(16) heterotic string. Most of the backgrounds have a classical worldsheet definition but are quantum string vacua in the sense that string loop corrections change the curvature of spacetime. At one-loop, the change in the cosmological constant is positive but never sufficient to uplift to de Sitter space. By computing the spectrum of spacetime scalars, we show that there are no tachyons below the BF bound. We also show that there is a solution with no spacetime NS-NS flux. This background has no classical string limit. Surprisingly, there appears to be parametric control over these constructions, which provide a framework for exploring quantum gravity and holography without supersymmetry.

Unconditional personal self-acceptance as a humanistic trait of a psychologist

Becoming a future psychologist in a university environment is a complex and multifaceted process. This process includes the formation of professional skills, as well as the psychological enrichment of the inner world of the future psychologist. Personal and professional development of a psychologist are interconnected and combined in the process of self-development. The discovery of self-actualization horizons requires a psychologist to have a number of humanistic qualities, such as a positive attitude toward oneself and others, empathy, congruent self-expression, and confidence. Unconditional true self-acceptance is the basis of the training of an effective psychologist. Undoubted self-acceptance reflects internal recognition and respect for oneself as an individual capable of independent choices and awareness of one’s feelings, thoughts, intentions, and motives. This includes accepting yourself as a whole and benevolent-demanding attitude towards yourself. Conditional self-acceptance, on the other hand, implies a mistrustful and critical attitude towards oneself, which can violate the integrity of the individual, negate one’s own self-concept. The structure of conditional self-acceptance of future psychologists consists of three interrelated components: the inability to consciously perceive and understand one’s own emotional and sensory states, the inability to overcome protective mechanisms that prevent the acceptance of one’s own experiences and emotions, and the rejection of real inner desires and motives, which can lead to personal destructiveness. The functional structure of unconditional self-acceptance contains at least four interdependent components: awareness of one’s own emotions, body states and feelings, a positive attitude towards oneself as an individual that ensures integrity and self-development, empathy for others and their psychological support, existential openness to the world and a tendency to self-actualization. For future psychologists, unconditional self-acceptance is the basis for the formation of professional self-awareness and the ability to provide qualified assistance to clients with the psycho-existential resources of one’s own personality. It is argued that self-acceptance affects the development of such humanistic qualities as unconditional acceptance of others, empathy in relationships, the ability to be internally open to communication, the ability to establish and maintain contacts with others, as well as the ability to tolerate, dialogue, and find a compromise. The listed characteristics are the basic qualification traits-qualities of a psychologist, which effectively determine his professional success in interaction with clients. The model of the development of unconditional self-acceptance of future psychologists proposed in the article reflects a constant progressive change in the orientation of the components of the structure of self-acceptance (from conditional to unconditional), and also reveals the psychological conditions and mechanisms for the development of productive unconditional self-acceptance of an individual. To actualize and implement the latter, psychological training is presented as an integral means of developing unconditional psycho-existential self-acceptance of the personality of future psychologists.As a result, the hypothesis was confirmed that unconditional self-acceptance positively causes the development of such humanistic personality traits of future psychologists as unconditional acceptance of others, empathy, tolerance, congruence, openness.

Characterization of trap evolution in GaN-based HEMTs under pulsed stress

In this paper, the evolution of traps in GaN-based high-electron-mobility transistors under pulsed thermal stress and the combined effect of thermal stress and electrical stress are studied. By applying impulse stresses of different powers to the device, collecting transient current response curves, and accurately extracting the time constant and absolute peak changes of the traps by employing the Bayesian inverse convolution theory time constant spectral technique, we analyzed the evolution of the traps under the action of impulse stress and clarified the influence and degradation mechanism of the thermal stress, as well as the combined action of thermal stress and electrical stress, on the evolution of traps. The results show that under pulsed stress, the decrease in electron mobility with increasing temperature leads to a decrease in device drain current, and the degradation of the device is exacerbated owing to channel hot-electron injection.

Enhancing EFL Learner Autonomy through Project-Based Learning: The Case of Secondary School Students

<em>With the 21st century constant changes and demands, heated debate on ways to enhance Moroccan EFL students’ autonomy has sparked the interest of stakeholders. Although learner-centered teaching has been recommended in the past few years, teacher-centered instructional styles are; however, predominating in real teaching-learning practices. Autonomous learning skills and self-directed learning are needed in the twenty-first century, and project-based learning is a way to respond to that requirement. The purpose of this paper is to investigate if project-based learning could enhance the autonomy of learners in a Moroccan EFL context. Similarly, this research aims at interviewing the presenters’ peers on their performance; a method whereby they could develop critical thinking skills. To achieve this purpose, data was collected through a self-assessment questionnaire and a semi-structured interview. The participants were a classroom of 17 Secondary (2nd baccalaureate) school students. Results demonstrated that project-based learning enhances learner autonomy and responded to the demands of the 21st century skills. Likewise, based on the findings, learners managed to improve their autonomy during the implementation of project-based learning, and levels of autonomy vary among learners. Future researchers need to take into consideration that not all learners maintain a positive view concerning project-based learning perhaps they are accustomed to teacher spoon-fed and hand hold; consequently, they become passive. To deal with this dilemma, teachers had better remind students repeatedly that project-based learning contributes in boosting their autonomy and prepares them for the post-graduation exigencies. </em>

The role of mitochondrial dynamics in disease.

Mitochondria are multifaceted and dynamic organelles regulating various important cellular processes from signal transduction to determining cell fate. As dynamic properties of mitochondria, fusion and fission accompanied with mitophagy, undergo constant changes in number and morphology to sustain mitochondrial homeostasis in response to cell context changes. Thus, the dysregulation of mitochondrial dynamics and mitophagy is unsurprisingly related with various diseases, but the unclear underlying mechanism hinders their clinical application. In this review, we summarize the recent developments in the molecular mechanism of mitochondrial dynamics and mitophagy, particularly the different roles of key components in mitochondrial dynamics in different context. We also summarize the roles of mitochondrial dynamics and target treatment in diseases related to the cardiovascular system, nervous system, respiratory system, and tumor cell metabolism demanding high-energy. In these diseases, it is common that excessive mitochondrial fission is dominant and accompanied by impaired fusion and mitophagy. But there have been many conflicting findings about them recently, which are specifically highlighted in this view. We look forward that these findings will help broaden our understanding of the roles of the mitochondrial dynamics in diseases and will be beneficial to the discovery of novel selective therapeutic targets.

Iterative Development: Going with the Flow to Improve Care.

Healthcare can benefit immensely from implementing an Agile mindset. Specifically, Agile principles of value-driven delivery, adaptive planning, and continuous improvement can exert a positive impact on projects-especially amid the constant changes in laws, evidence-based practices, and technology in healthcare. The best way to apply Agile is to combine the discipline and structure of a traditional linear model with the adaptability of iterative development. That mix allows for certain controls but with the flexibility for stakeholders to provide input and call for adjustments at different stages. To start, an organization must build teams of multidisciplinary personnel with diverse perspectives. Delivering value should be addressed as soon as possible by considering stakeholder priorities, using tools for continuous project planning, and employing retrospectives to provide feedback and identify root causes. When leaders embrace value-driven delivery, adaptive planning, and continuous improvement, healthcare projects can lead to positive results and ultimately improve patient care.

DIGITAL PLATFORM ARCHITECTURE FOR ENGINEERING EDUCATION MODEL

Digital platforms have become an essential part of engineering education's innovative transformation as a result of the rapid development of technology and constant changes in the field. This article examines and emphasizes the importance of developing a digital platform to provide resources and operational support for implementing the National Model of Engineering Education. The article describes the architecture of a modular digital platform. A study identifies what services are required, which user categories will use it, and which software components should be implemented. As a result of implementing a digital platform based on the proposed architecture, various categories of users will be able to access the necessary set of engineering profession-related services.

PRIUS: Applying Gamification to User Stories Prioritization

In the context of agile development methodologies, due to the volatile nature of requirements and constant changes, prioritizing requirements is often a problem. Requirements prioritization is a complex, collaborative, continuous, cyclical, and laborious process, resulting in low engagement. Gamification is a viable strategy for improving engagement in such processes, as it enhances activities by promoting experiences akin to those found when playing games. This paper proposes a gamified approach, called PRIUS, for requirements prioritization in agile software development. The approach combines a requirements prioritization technique - Wiegers Matrix - with game elements, aiming to promote stakeholders' engagement in the activity. The PRIUS Gamified approach was developed, and a supporting system was implemented. They promote the integration of gamification elements for prioritizing agile artifacts asynchronously. A controlled experiment was conducted, comparing the gamified version of PRIUS with a non-gamified version in an academic environment. The results suggest that the gamified approach positively impacts some aspects of engagement of users in requirements prioritization using agile software development.

A numerical study supplemented with theoretical analysis on streaming potential in a soft nanochannel influenced by ion partitioning and mobile surface charge-dependent wall slip

We consider the pressure-driven flow of an electrolyte in a soft channel with a hydrophobic charged surface coated with a diffuse polyelectrolyte layer (PEL) with constant volumetric charge density. The objectives are to enhance the streaming potential and electrochemical energy conversion efficiency in the modulated soft channel as well as to examine the influence of surface charge mobility-dependent slip velocity on the electrokinetics. The laterally mobile adsorbed surface charge modifies the slip velocity condition, which is coupled with the induced streaming potential. The ion partitioning effect arises due to the step change in dielectric constant between the PEL and the electrolyte that modifies the distribution of ions, which is incorporated through the Born energy difference of ions. The nonlinear coupled set of equations governing the electrokinetics in a soft channel is solved numerically through a control volume approach. A simplified model based on the Debye–Hückel approximation under certain limiting conditions is also derived, which compares well with the present numerical model for a lower range of charge density and non-overlapping Debye layers. We find that a modulation of a nanochannel by coating a PEL of lower dielectric constant on hydrophobic charged walls can significantly enhance the streaming current and energy conversion efficiency. In contrast with existing studies, we find that the mobile surface charge can have a positive impact on the electrochemical energy conversion efficiency in a soft nanochannel. The mobility of the surface charge attenuates the streaming current in a PEL-free channel and can enhance the streaming current for a suitable choice of PEL volumetric charge density.

STUDY OF THE STRUCTURAL AND ELECTRICAL EFFECTS OF THE T2−xAgxBa2Ca2Cu3O10+ SUPERCONDUCTING WITH PARTIAL REPLACEMENT OF SILVER WITH THALLIUM

In this manuscript, the partial substitution of thallium by silver and its effect on the superconducting properties of T2−xAgxBa2Ca2Cu3O10+ is studied with x = 0, 0.15 and 0.25. The samples were prepared by the solid state reaction method. The electrical conductivity was examined using the four probes technique to determine the critical temperature Tc. It was found that increasing the proportions of silver for all produced samples increases the critical temperature. It was also found that the best compensation ratio for x is 0.25, which gives the highest critical temperature, Tc. The ultrastructural properties of the samples were studied using X-ray diffraction. X-ray diffraction study showed that all the prepared samples had a tetragonal structure, with a clear change in the lattice constants. The results also showed that the samples were clearly affected by the replacement of silver with thallium. It was shown that the partial replacement of Tl with Ag promoted the formation of the superconducting 2223 phase