Input–output efficiency model of urban green-energy development from the perspective of a low-carbon economy

With the acceleration of urbanization, cities are the main targets for carbon neutrality and urban energy is the terminal of energy consumption and the integration point of various energy systems. Therefore, there is a need to promote the development of urban green energy and achieve low input and high output to achieve a low-carbon economy in cities. Previous studies have not considered the input–output efficiency of urban green-energy development. This study fills this gap. Based on the economic–energy–environmental framework, an input–output efficiency-evaluation index system for urban green-energy development was constructed. Based on improved data-envelopment analysis, a comparative evaluation of the input–output efficiency of green-energy development was carried out in 30 provinces in China in 2019. Considering the differences in regions, the development of urban green energy in different provinces was classified. From the perspective of a low-carbon economy, economic growth factors and environmental constraint factors were set. Together with the generalized Divisia index approach, the input–output efficiency optimization directions of urban green-energy development were obtained. The results showed that the input–output efficiencies of urban green-energy development in Jiangsu, Zhejiang, Fujian, Inner Mongolia, Ningxia and other provinces and cities were relatively high. Provinces with faster economic development and higher environmental carrying capacity have advantages after optimization and will become pilot areas for the development of urban green energy. This research provides a reference for the development of urban green energy in various provinces from the input and output perspective.

The Influence Factor Analysis of Symmetrical Half-Bridge Power Converter through Regression, Rough Set and GM(1,N) Model

Analysis of power converter performance has tended to be engineering-oriented, focusing mainly on voltage stability, output power and efficiency improvement. However, there has been little discussion about the weight relations between these factors. In view of the previous inadequacy, this study employs regression, rough set and GM(1,N) to analyze the relations among the factors that affect the converter, with a symmetrical half-bridge power converter serving as an example. The four related affecting factors, including the current conversion ratio, voltage conversion ratio, power conversion ratio and output efficiency, are firstly analyzed and calculated. The respective relative relations between output efficiency and the other three factors are obtained. This research can be referred to by engineers in their design of symmetrical half-bridge power converters.

Evaluation of Input-Output Efficiency of Sports Industry Based on SWOT-PEST Model

This article takes the macro-environmental sports industry as the research object. Firstly, based on the development and characteristics of the sports industry, the article uses the principle of data envelopment analysis to analyze its input and output efficiency and finds out its current problems. In addition, the SWOT analysis method is used to conduct a comprehensive analysis of the external and internal environment influencing the efficiency of the sports industry and propose corresponding development countermeasures. Through the comparison of efficiency evaluation methods, the data envelopment analysis method is proposed to evaluate SWOT efficiency. Secondly, on the basis of pointing out the guiding ideology and basic principles of the evaluation system, four input indicators and four output indicators are specifically selected to form the SWOT input-output indicator system. Thirdly, we introduce the PEST model, focusing on its extended BCC model and use it to make empirical analysis of the SWOT efficiency of regions and provinces. The analysis results show that the efficiency of regional SWOT is not optimal and that there are problems such as input redundancy and insufficient output. Through further analysis, it is concluded that the main reason for the inefficiency of regional SWOT is the unreasonable SWOT input structure and insufficient output value of high-tech industries. We use the analytical framework of this method to clarify the current macro-competitive environment of the sports industry, and use the constructed index system to determine whether the sports industry environment in a region is good or bad. In the selection of indicators, we must carefully analyze their connotations, so that the evaluation index system can accurately evaluate the region’s sports industry environment.

Efficiency of Environmental Protection Expenditures in EU Countries

Environmental protection policy is a widely discussed issue in scientific works. However, special attention should be also paid to the effectiveness of expenditures on environmental protection, and this is the main goal of this paper. The countries of the European Union were selected for this analysis due to the fact that, in recent years, this region has become an informal world leader with respect to the implementation of policy measures in the field of environmental protection. For that reason, the data envelopment analysis methodology was used, which allows the calculation of input-output efficiency for the years 2005–2015. The analysis shows that, among the 30 analyzed countries, the most effective in environmental protection actions is Finland. The hypothesis that higher environmental protection expenditures does not result in better environmental results has been confirmed. Our analysis confirmed the problem of the deteriorating efficiency of environmental expenditures across the selected European Union Member States, caused by increases in spending. This research may contribute to the discussion on environmental protection policy design and its assessment, as well as environmental policy results measurement.

Performance verification test of coaxial centrifugal clutch for motorcycle transmission system

With the popularization of motorcycles, the demand for motorcycles is getting higher and higher. Therefore, the improvement of power output, the reduction of pollutants discharged, the replacement of waste, the improvement of efficiency and the reduction of fuel use, are also relatively important. Stop-and-go on urban driving will keep the clutch in a state of being engaged and not engaged. The clutch cannot be engaged and is constantly worn. The output efficiency of the CVT belt-type continuously variable transmission system clutch used in the transmission is only about 70~80%. Transmission efficiency. Furthermore, since the traditional CVT belt-type system clutch mainly relies on the action of the centrifugal roller to change the reduction ratio, when encountering different driving conditions and need to accelerate and decelerate, this will make the working area of the internal combustion engine in an unstable state. The matching structure between the automatic clutch weight and the telescopic spring in the reciprocating separation state and the fitted state is replaced, which effectively reduces the problem of uneven contact surfaces of the plates in the past, and prevents the elastic aging from affecting the uniform transmission of power, resulting in the entire dry clutch The life span of the engine is improved and the efficiency of power transmission is maintained, thereby reducing fuel consumption and producing more complete engine power. Therefore, the “Design Performance Verification of Coaxial Contact Centrifugal Ball Clutch” is proposed mainly to verify that the coaxial contact centrifugal ball clutch has better performance than the CVT belt-type clutch.

Thermodynamic Performance of a Brayton Pumped Heat Energy Storage System: Influence of Internal and External Irreversibilities

A model for a pumped thermal energy storage system is presented. It is based on a Brayton cycle working successively as a heat pump and a heat engine. All the main irreversibility sources expected in real plants are considered: external losses arising from the heat transfer between the working fluid and the thermal reservoirs, internal losses coming from pressure decays, and losses in the turbomachinery. Temperatures considered for the numerical analysis are adequate for solid thermal reservoirs, such as a packed bed. Special emphasis is paid to the combination of parameters and variables that lead to physically acceptable configurations. Maximum values of efficiencies, including round-trip efficiency, are obtained and analyzed, and optimal design intervals are provided. Round-trip efficiencies of around 0.4, or even larger, are predicted. The analysis indicates that the physical region, where the coupled system can operate, strongly depends on the irreversibility parameters. In this way, maximum values of power output, efficiency, round-trip efficiency, and pumped heat might lay outside the physical region. In that case, the upper values are considered. The sensitivity analysis of these maxima shows that changes in the expander/turbine and the efficiencies of the compressors affect the most with respect to a selected design point. In the case of the expander, these drops are mostly due to a decrease in the area of the physical operation region.

Parity–Time Symmetric Model and Analysis for Stable Multi-Load Wireless Power Transfer

A noticeable challenge for a multi-load wireless power transfer system is to achieve stable power transfer under a dynamic change in coupling conditions. It was proposed that the parity–time symmetric wireless power transfer (PT-WPT) system can achieve stable output efficiency for a single receiver when tuned at the purely real eigenfrequency. However, in the case of higher order, PT symmetric systems usually cannot maintain the real eigenfrequency. To address the issue, a high-order PT-WPT model was established using coupled mode theory (CMT) theory in this paper, and the eigenfrequency of the multi-load PT-WPT system was analyzed. Here, we propose that, theoretically, the system can work at the purely real eigenfrequency by impedance matching. The transfer efficiency of the multi-load PT-WPT system when the system works at the real eigenfrequency was analyzed. The results of the numerical simulation show that the multi load PT-WPT system can maintain stable output efficiency under a dynamic change in coupling conditions. In the long run, our work provides a new possibility for the stable transmission of the multi-load wireless power transfer system.

Research on the Public Sports Service Efficiency and Spatial-Temporal Evolution in China

Taking 31 provinces as the research object, this paper constructed the input-output efficiency evaluation index system of public sports service in China. The paper evaluated the input-output efficiency level and spatial-temporal pattern of public sports services using the methods of data envelopment analysis and exploratory spatial data analysis. The results show that: (1) The average comprehensive super-efficiency value of public sports service in 2016 was higher than that in 2008, and the provinces with the comprehensive super-efficiency value greater than 1 increased, but the difference between provinces in 2016 was more obvious. (2) Compared with 2008, the efficiency distribution of public sports service in 2016 is more balanced among the three regions, the difference between the eastern region and the central region is reduced. (3) The efficiency of public sports service has different spatial correlation in the geographical spatial distribution, and this correlation shows the reverse in the two measurements.

How Does Low-Density Urbanization Reduce the Financial Sustainability of Chinese Cities? A Debt Perspective

Low-density urbanization threatens urban social and ecological sustainability not only directly by excessively encroaching on suburban farmland and ecological space, but may also indirectly do so by undermining the financial basis of sustainable urban development. To address this relationship, this study empirically examines the effect of low-density urbanization on local government debt by using panel data of prefecture-level cities in China from 2006 to 2015. Results show that the scale of local government debt increases significantly with a rise in urban expansion. Furthermore, this study found that low-density urbanization affects local government debt in two ways. First, low-density urban expansion reduces the land output efficiency, which decreases potential fiscal revenue and thus increases local government debt. Second, low-density urban expansion raises the construction and maintenance expenditure of urban infrastructure, which increases the demand for urban construction financing and thus pushes up the scale of debt. The results of the heterogeneous study indicate that low-density urbanization significantly affects local government debt mainly in Central/Western regions, small and medium-sized cities, cities with high fiscal stress and development pressure, and residentially expanding cities. On the contrary, low-density urbanization has no significant effect on the Eastern regions, large cities, cities with low fiscal stress and development pressure, and spatially expanding cities. This study theoretically explored and empirically verified a critical indirect effect of low-density urbanization on urban sustainability by increasing fiscal risks, which is, and will continue to be, a common and vital challenge faced by cities in China and other rapidly urbanizing developing countries.