Suchergebnisse

We investigated the association between social support and negative emotions in Chinese people aged 65 years and over, by comparing those who still had a spouse with those who had been widowed. Data were drawn from the 2018 Chinese Longitudinal Health and Longevity Survey of Elders.
The results showed that there were significant differences between those who were widowed and those whose spouse was still alive in terms of the negative emotions of uselessness and loneliness, but not anxiety. The more informal and formal social support (excluding economic support and medical
insurance) these older adults had, the fewer negative emotions they felt. These findings provide theoretical and practical insights for scholars who are researching the topic of old age, and also offer practical insights for older adults to maintain their health.

Utilizing the regional data of China covering 29 provinces and municipalities during 1990-2009, this article outlines a systematic approach to investigate the relations between public participation, government regulation and environment pollutions. Results show that government regulation influences environment pollutions while environment pollutions have no influence on government regulation in the short term. Besides, environment pollutions and public participation have no influence on each other. In the long term, there exists the granger causality among public participation, government regulation and environment pollutions. Our results also show that improving the public participation's ability in environmental protection and strengthening government regulation's intensity are the basic measures to improve China's environmental pollution in the long run.

In this work, the possibility of a switchable metamaterial absorber is proposed to control absorption bandwidth in the WiMAX/LTE (worldwide interoperability for microwave access/long term evolution) band, by taking advantage of the low cost and myriad structural configurations afforded by water-based metamaterials. By exploiting truncated cone-type resonators, the fractional bandwidth of 27.6% of absorption spectrum can be adjusted flexibly to be 7.4% of the narrow-band absorption depending on the volume of injected water, in both simulation and experiment at room temperature. In particular, this control method can be applied stably for different temperature of injected water. We describe a dynamic mechanism for broadband MA, as well as a principle for controlling the absorption characteristics utilizing a combination of magnetic resonance and perfect impedance matching. These results are a stepping-stone towards the realization of smart electronics integrated with multi-functional metamaterials in military, biomedical, communication and other fields.

AbstractThe development of electric vehicles (EVs) exhibits rapid and remarkable progress nowadays, serving as a crucial route to accomplish the target of mitigating greenhouse gas emissions. As an integral part of the thermal management system oriented toward electric vehicles, the heat pump air conditioning system for electric vehicles is the result of a comprehensive choice that trades off the cooling and heating performance, environmental performance and economic cost. Particularly, different regions around the world suffer varying cooling and heating challenges due to the complicated climatic characteristics. Thus the most suitable refrigerant and system cycle structure may differ. This paper focuses on evaluating both the refrigerants and cycle structures to screen the most suitable choice. According to the climate conditions of different cities, the annual energy consumption, life cycle climate performance, and economic cost of the basic system (Base), two-stage compression system (TSC,IC), and vapor injection (VI) system with CO2, R134a, and R1234yf refrigerants respectively, are quantitatively analyzed and evaluated. Subsequently, through comparative analysis, a comprehensive selection map for heat pump systems in electric vehicles worldwide is developed and the most suitable heat pump air conditioning system for each cites is determined. The results can provide a selection reference and decision-making for the air conditioning system of electric vehicles from regional considerations. It was found that the CO2 HPACVI was recommended for cold regions to meet both environmental and economic requirements. In warm region, the R1234yf HPACBase system was recommended to be used. For regions transitioning from cold to warm climates, the R1234yf HPACVI system was suggested. In hot region, the R1234yf AC system was recommended.