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Salt-Retaining Asphalt Mixture Technology for Melting Snow and Ice
No full textCompared with many active snow melting and de-icing technologies, salt-storing asphalt pavements offer higher engineering application value due to their simple construction and cost-effectiveness. The incorporation of salt-storing materials into asphalt mixtures enhances the active snow and ice melting performance of the pavement but may adversely affect its serviceability. To further improve the comprehensive performance of salt-storing asphalt mixtures, this paper systematically summarizes the research progress on salt-storing materials, the pavement performance of salt-storing asphalt mixtures, and their snow and ice melting performance from three aspects: the development of salt-storing materials, the pavement performance of salt-storing asphalt mixtures, and their snow and ice melting performance. First, the types of salt-storing materials and the research progress of various salt-storing materials with different carriers are classified and introduced. Second, the design of mixtures and the impact of different salt-storing materials on pavement performance are reviewed. Additionally, the evaluation methods for snow and ice melting performance of salt-storing asphalt mixtures and long-term prediction methods for snow and ice melting performance are summarized, and future research directions are outlined
Market Dynamics and Institutional Challenges in Urban Rental Housing: An Evidence from Kumasi, Ghana
No full textHousing as shelter is a basic necessity against the adversaries of the weather, a haven of safety for precious items, a privacy for social life, security for better behaviour, and as a real estate property. As an asset, it is valuable for life self-fulfilment and actualisation consequent upon its economic and socio-cultural externalities. This study analyses Kumasi\u27s rental housing market, structured across public, formal private, and informal sectors, each exhibiting distinct market failures. The public sector operates as a state monopoly with subsidised rents causing chronic shortages, while the formal private sector\u27s oligopolistic structure leads to affordability challenges. The dominant informal sector suffers from severe information asymmetry, with landlords exploiting pricing power amid housing shortages. Methodological limitations include reliance on rental agent data rather than direct landlord-tenant engagement. The problems in the housing sector include fragmented market actors and heterogeneous products. Findings highlight the need for regulatory reforms to improve transparency, including establishing a Rental Housing Secretariat and standardised contracts. The research advocates integrating rental housing into urban policy, challenging Ghana\u27s homeownership bias. Practical recommendations include regulating rental agents, incentivising affordable housing development, and strengthening tenant protections to address power imbalances. The government should scale down its direct intervention in housing provision and policy terms, giving rental housing the appropriate attention it deserves as a complementary option to homeownership. Alongside, the private sector will be tuned in as the engine of rental housing delivery. This work contributes to housing justice by proposing market-based solutions to informality and affordability challenges in Ghana\u27s urban housing sector
Preparation Methods of Modified Asphalt from Waste Plastic: A Review
No full textThis paper provides a systematic review of the current research status and application prospects of waste plastic modified asphalt (WPMA) technology. It begins by outlining the severity of global plastic pollution and the urgency of recycling waste plastics, emphasizing that its application in asphalt modification represents an effective pathway for high-value utilization. The article not only presents the current state of waste plastic recycling but also focuses on analyzing three preparation processes: wet process, dry process, and wet-dry composite process, along with a comparative evaluation of their advantages and disadvantages
Impact of COVID-19 on Life-Space Mobility, Physical Fitness and Motor Abilities in Older Japanese Women with Social Participation
No full textObjectives: This study aimed to examine changes in physical fitness and motor abilities among older adult Japanese females who participated in social activities during the pandemic and prepandemic periods.
Methods: This study included 60 older adult females whose physical fitness and motor abilities were measured in 2014 and 2017 (the 2014 group), and 15 older adult females who participated in the same tests before the COVID-19 pandemic in 2019 and during the pandemic in 2022 (the 2019 group). Hand grip strength (upper limb strength), knee extension strength (leg strength), standing on one leg with eyes open and using functional reach (balance ability), 10-m maximal walking (walking ability), cross-step moving on four spots, and hip displacement in the anteroposterior direction (hip function) were selected as parameters. Test results were statistically analyzed using two-way ANOVA to examine the interaction effects of group and chronological changes, followed by post-hoc comparisons using the Tukey Honest Significant Difference test.
Results: Significant chronological changes were found between the 2014 and 2019 groups in one-leg standing with eyes open (46.92–36.84 s and 39.44–29.05 s), functional reach (31.18–29.58 cm and 32.69–31.53 cm), and hip displacement in the anteroposterior direction (23.99–29.17 cm and 26.16–20.25 cm). The cross-step moving on four spots test revealed a notable chronological change (5.34–6.40 s), and life-space mobility only decreased in the 2019 group.
Conclusion: Among older adult females who participate in social activities, the COVID-19 pandemic was associated with a significant compression of life-space mobility. While balance already showed small, age-related declines before the pandemic, the pandemic period was additionally characterized by a reduction in hip function, indicating mobility constraints beyond normal aging
Amplitude Modulation and Coexisting Attractors in a Slow-Fast Duffing System
No full textThis paper aims to investigate the influence of amplitude modulation and coexisting attractors on the formation mechanism of complex bursting oscillations in slow–fast coupled nonlinear systems. Taking a modified three-dimensional van der Pol–Duffing system as the research object, a parametric excitation with frequency far less than the natural frequency is introduced into the system, establishing a slow–fast system model with two-scale coupling characteristics in the frequency domain. Regarding the excitation term as a slow-varying parameter, the equilibrium points, limit cycles, and their bifurcation structures in the fast subsystem are systematically analyzed, revealing the coexistence conditions of different attractors and their impact on the dynamics of the full system.
When the modulation amplitude is relatively small, the slow evolution process of the system becomes notably extended, showing typical quasi-static relaxation–oscillation characteristics. As the modulation amplitude increases, these oscillations vanish rapidly, and the system transitions to a steady equilibrium or an aperiodic oscillatory state. Further investigation reveals that the coexistence of multiple attractors in the fast subsystem can result in diverse bursting behaviors of the full system: trajectories may remain within a single attraction basin or sequentially traverse several basins, thereby generating merged bursting oscillations. Moreover, due to the inertia effect, trajectories may directly cross parameter regions associated with specific attractors, leading to the disappearance of corresponding bifurcation phenomena. When the excitation frequency decreases to a sufficiently low value, previously vanished attractors may re-emerge. If the interval between two types of codimension-1 bifurcation points is extremely narrow, the system may also display compound bursting patterns analogous to those caused by codimension-2 bifurcations.
The research in this paper reveals the synergistic influence mechanism of coexisting attractors in slow-fast systems on relaxation oscillations and bursting dynamics under amplitude modulation conditions, enriching the multiscale dynamical theory of nonlinear oscillators and providing new theoretical references for the study of modulation-induced dynamical evolution in other complex nonlinear systems
Analysis of the Influence of Blast-induced Free Surface on Rock Fragmentation Characteristics in Deep-hole Blasting with Numerical Analysis
No full textTo thoroughly investigate the influence of blast-induced free surfaces on rock fragmentation characteristics, a three-dimensional blasting model was established using ANSYS/LS-DYNA software. The ALE fluid-structure coupling algorithm and the RHT rock constitutive model were employed to simulate the blasting process under different blast-induced free surface conditions. The study analyzed the impact of free surfaces generated from previous blast holes on subsequent blast hole rock failure. Simulation results demonstrate that: 1) With the increase in the number of blast-induced free surfaces, the damage range of the rock mass progressively increases; 2) The damage proportion reaches 15.1% with a single free surface, 20.3% with two free surfaces, and 32% with three free surfaces. The data clearly indicate that as the free surfaces increases, the rock damage range expands, and the fragmentation effect becomes more pronounced. This research on rock damage range under varying free surface conditions provides a theoretical basis for optimizing blast design and controlling rock fracture propagation
Shell Noun Usage in Science Undergraduate Academic Writing: Insights from Mukuba University, Zambia
No full textThis study examined the use of shell nouns in the academic writing of science undergraduate students at Mukuba University, Zambia, focusing on their frequency, patterns, and functions across multiple disciplines. The topic was chosen due to the critical role of shell nouns in enhancing coherence, formality, and objectivity in academic writing, which are essential skills for scientific communication. Grounded in Halliday and Hasan’s theory of cohesion, the research aimed to (1) investigate the frequency of shell noun use across disciplines, (2) identify patterns in their usage across academic years, and (3) evaluate their functional contributions to coherence, formalization, and objectivity in student writing. A qualitative approach was employed, involving the analysis of written samples from disciplines including Biology, Chemistry, Public Health, Nutrition Science, Agricultural Science, Computer Science, Environmental and Climate Change, and Biomedical Science. The data set consisted of lab reports, research papers, and essays collected from first-year to final-year students. The data analysis involved frequency counts and thematic coding to identify trends and patterns in shell noun usage. The findings revealed notable disciplinary variations, with Chemistry and Biomedical Science demonstrating higher frequencies of shell noun use. Shell nouns played a vital role in maintaining textual coherence, formalizing tone, and enhancing objectivity in the students\u27 writing. More advanced usage was evident among final-year students, suggesting a developmental progression in academic writing skills. However, challenges such as inconsistent use and difficulty applying shell nouns effectively in complex writing tasks were also identified. The study highlighted the importance of targeted pedagogical interventions, recommending the inclusion of explicit instruction on shell noun usage in writing curricula. Suggestions for future research included expanding the sample size, incorporating a broader range of genres, and adopting a longitudinal approach. By examining linguistic features in academic writing within a sub-Saharan African context, this research provided valuable insights for educators seeking to enhance writing instruction and support student success
A Model Study of The Impact of Enlightenment Rate on The Dynamics of Typhoid Fever
No full textIn this study, a mathematical investigation of the effect of enlightenment rate on the spread of typhoid fever is considered, using a system of nonlinear first order ordinary differential equations and a MATLAB ODE45 numerical scheme. The result shows that a decrease in vaccination rate significantly increases the size of the susceptible () class and the response functions, or thereby heightening the tendency for the disease to be endemic. If then the typhoid infection will spread throughout the population, but if then the infection will not be able to take hold and will eventually die out. Furthermore, it was shown that, the basic reproduction number has the tendency to reveal faster if a disease will result in an epidemic than the effective reproduction number. Finally, as enlightenment rates approach zero, it was observed that, over time, the disease will result in an epidemic. It is therefore recommended that enlightenment rate of the exposed, enlightenment rate to go for treatment and enlightenment rate to go for vaccination should be taken seriously by policy makers in order to stem the spread of typhoid
High Efficiency Bidirectional Dual Active Bridge DC/DC Converter for Level 3 Electric Vehicle Charging
No full textIn the current scenario, slowly but surely we are getting familiar with the concept of “electric vehicles” or “charging stations”. It’s only been a brief period of time since the notion of “electric vehicles” or EVs has been taken up in society. Many different types of “electric vehicles” are there like hybrid, plug-in hybrid, or battery-powered “electric vehicle”, one thing is clear that “electric vehicles” are intended to stay. Advancement in battery technology has allowed for lighter vehicles, longer battery “efficiency”, and cost “efficiency” as well. With these developments, the public\u27s acceptance of an alternative fueled vehicle has also grown.
In this review paper design of “Dual Active Bridge (DAB) bidirectional DC/DC converter” for level 3 “electric vehicle (EV) charging” application is presented. To support battery charging and discharging applications, DAB topology is preferred due to its modular and symmetrical structure which facilitates high power throughput and bidirectional mode of operation. Simulation done using PLECS (Piecewise Linear Electrical Circuit Simulation) and MATLAB software. We have : “Single Phase Shift Control (SPS)” and “Extended Phase Shift Control (EPS)”, 97% peak “efficiency” and 96% full load “efficiency”, secondary “voltage”: “700V-800V DC” and primary voltage: 300 V-500V DC. This design is preferred where power density, cost, weight, “galvanic isolation”, high voltage conversion ratio, and reliability are critical factors
Haitian Immigrants and the Coronavirus Pandemic in Brazil
No full textSocial and environmental epidemiology recognizes that analyzing the social and living contexts in which populations are embedded is essential for broadening our understanding of health and disease processes, as well as improving research on disease distribution. This theoretical essay aims to discuss the repercussions and challenges faced by the Haitian population received in Brazil during the COVID-19 pandemic. It is based on a review of the literature and discussions occurred in the Socio-Environmental Epidemiology class of the Postgraduate Program in Health Sciences in a university in southern Brazil. Given the precarious conditions in which Haitian immigrants live in Brazil and the impact on their health, this essay highlights that the vulnerabilities already present in this population were exacerbated during the pandemic, further worsening their living conditions and health status. Haitian immigrants appear to have experienced the effects of the pandemic more intensely due to intersectional factors, particularly their immigrant status combined with socioeconomic difficulties. This underscores the urgent need for public policies aimed at reducing the inequalities affecting this population, ensuring their effective integration into Brazilian society through improved access to quality employment, housing, food, income, and healthcare services