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Dissolved gas analysis is important for the early warning and diagnosis of transformer faults. Aiming at the problems of numerous types of features for dissolved gas in oil and the insufficient analysis of fault associated features, a new fault diagnosis method for oil-immersed transformers based on feature selection of dissolved gas in oil is proposed. Firstly, the derivation of original features for dissolved gases is completed. The optimal combination of features is selected by calculating the importance of features for fault diagnosis based on random forest (RF). Then, the tree-structured parzen estimator (TPE) is used to realize the parameter optimization of the RF model, and the TPE-RF diagnostic model is obtained. Combined with the various evaluated indicators, the proposed method is proved to be able to diagnosis the transformer faults accurately. Finally, the TreeSHAP model is introduced to analyze the importance of the features corresponding to each fault, and the specialized features for each fault are selected. According to the case of transformer in operation, the applicability of the method in the power system is discussed, and the effectiveness of the method is verified.

The distribution of surface water is highly dynamic both spatially and temporally, and very sensitive to climate change and anthropogenic interference, especially in highly urbanized regions. The abundance of surface water and its spatiotemporal distribution indicate the availability of water resources and the difficulty of water development and utilization. Consequently, it is essential to perform reconstruction and trend prediction of surface water body changes with high accuracy in time and space for scientific research as well as for practical purposes such as flood prevention, sustainable development of water resource systems, and regional ecological management. The Guangdong-Hong Kong-Macao Greater Bay Area (GBA) is highly developed economically and societally and is characterized by a subtropical humid monsoon climate with an extensive distribution of surface water bodies. Under the integrated pressure of continuous natural environmental change and intense human activity, concerns regarding both the water environment and water security in this area is increasing at an unprecedented rate. In this study, we collected water distribution information from 2001 to 2020 at 5-year intervals, as well as annual and monthly water extent dynamics data for the GBA from the Global Land Analysis & Discovery database. Subsequently, the spatial and temporal changes in water extent, frequency, and distribution characteristics in the last two decades were investigated using remote sensing and geographic information system methods. Finally, elastic analysis was conducted to identify the sensitivity of water body changes to changing environmental parameters, including precipitation, temperature, and urbanization. Focusing on the national and regional strategic needs of GBA, the research objectives of this study were to explore the mechanism of temporal and spatial dynamics of the water extent and frequency, trace the volatile areas of regional water changes, clarify the driving factors of water distribution changes, and provide a basis and guidance for comprehensive management of water resources, flood disaster prevention, and control in areas with high human activity. The first result shows that in the last two decades, the water extent and frequency of the GBA are on a decreasing trend, with an average decreasing rate of 50, 31, and 11 km2/a for maximum, annual, and permanent water extent, respectively, while a large proportion of seasonal water bodies changed into permanent and flood-prone bodies during the same period. Second, although the water frequency showed distinct spatial and urban/rural heterogeneity, it was on a decreasing trend in most of the GBA, except in the eastern region. A steeper decline was observed in urban areas, especially the emerging urban regions. Third, the dike-pond system decreased both in water extent and frequency, while the large and medium-sized lakes and reservoirs in the upper catchment increased in extent. Finally, elastic analysis suggests the dominant driving factor of regional water body change is land use change, which contributed more than 80% to the decrease in water extent, and the reservoir increase is mainly due to precipitation change. The results of this research provide scientific guidance for regional water resource guarantee, water environment optimization, and sustainable development promotion. In addition, this research can serve as a decision-making reference for the development of the "One Belt One Road" national strategy and Guangdong-Hong Kong-Macao Greater Bay Area.

Background: Children’s physical health is an important resource for a country’s future construction. However, researchers found that the physical fitness of young children around the world has declined during the two decades, from 1992 to 2012. The decline in the physique of young children has caused widespread concern around the world. Children’s main living places are families and kindergartens, so this research explores the impact of family factors on children’s body mass index (BMI) from the perspective of family attitudes, children’s sports participation, and screen time.Methods: A cross-sectional study was used to conduct a questionnaire survey of children in China. A total of 600 children were investigated, and 589 valid questionnaires were obtained. SPSS21.0 statistical analysis software was used for descriptive analysis, mean comparison, and correlation analysis of the data. AMOS 21.0 was used to construct a structural equation model and carry out path analysis.Results: (1) There are significant differences in children’s family sports attitude, sports participation, screen time, and BMI with different family structures, and parents’ education levels. (2) Family sports attitude is significantly positively correlated with parents’ education levels and children’s sports participation, and negatively correlated with children’s screen time and BMI. (3) Children’s sports participation and screen time play a chain-mediating role between family sports attitude and children’s BMI, and the role is a complete mediating role. Therefore, family sports attitudes can affect children’s physical health by affecting children’s sports participation and screen time. To promote children’s physical health, we should pay attention to the intervention of family sports attitude. (4) The mediating effects of exercise participation and screen time are similar in different family structures, so the structure of this study can be applied to different family structures.Conclusions: Children’s family sports attitude, sports participation, and screen time can affect children’s BMI. Children’s screen time and sports participation play a chain-mediating role in the influence of family sports attitudes on the path of children’s BMI. The results of this study will provide a useful reference for teachers and parents to control children’s physical health.

In view of problems of low power quality, low cruising power, short service life of battery, separation between battery charging device and locomotive driving system existed in current charging system of mine-used electric locomotive with lead-acid battery, a new integrated on-board charging system was designed. The system is composed of the front-stage PWM rectifier circuit and the back-stage Buck circuit in series. When charging, the motor windings are reconstructed into the boost inductance of the PWM rectifier circuit to form an integrated on-board charging and discharging circuit. The supercapacitor is used to replace the battery as the energy storage element, which can realize quick on-board charging and discharging function. The simulation results show the system has shorter charging time and higher efficiency, and can realize functions such as power factor correction, ripple suppression, efficient and rapid charging and discharging compared with the traditional charging system.

Private enterprises occupies an important position in China’s economic development. They have played an important role in maintaining stable economic growth, promoting entrepreneurship, increasing employment, providing taxes, and improving people’s lives. They are an important force in promoting highquality enterprises. Based on the analysis of relevant data, this paper concludes that the financing difficulties of private enterprises are caused by both themselves and the investors, and provides countermeasures from financial system reform, Build a risk prevention mechanism, information platform construction, and enterprise self-management, etc, aiming to solve the private economy Practical problems.economic development in China. Financing is an important condition for the healthy development of private enterprises, and financing has always been a major problem for the development of private.

The emergence of many efficient optical field modulation methods and planar optical devices is attributed to the continuous research of geometric phase. Nevertheless, conjugate symmetry of the geometric phase limits the multiplexing of metasurfaces. To overcome this limitation, integrating the propagation phase and the geometric phase to achieve self-decouped metasurfaces can effectively double channel capacity. Herein, a more in-depth derivation of Jones matrices is conducted, leveraging two degrees of freedom offered by the propagation phase and the geometric phase. This approach enables complete modulation in circular polarization channels. By designing the phase difference between a fast axis and a slow axis, energy allocation between different channels can be controlled. It means independent complex amplitude modulation is achieved. On this basis, the geometric phase is introduced to realize tri-channel multiplexing metasurfaces. To verify the feasibility of this method, two metasurfaces are designed, including a bifocal metasurface with adjustable energy allocation and a tri-channel multiplexing metasurface. The proposed multifunctional metasurface offers new insights into wavefront multiplexing for communication systems. [ABSTRACT FROM AUTHOR]

This study investigates how (i.e., through what mechanism) and when (i.e., under what conditions) goal-oriented self-regulation behaviors improve college students' psychological well-being. On the basis of data from 74 s-year Chinese college students in a weekly diary study (296 observations), we conducted a moderated mediation model and found that goal-oriented self-regulations behaviors (i.e., planning, monitoring, controlling, and reflecting) were positively related to college students' psychological well-being through increased academic performance. Further, such an indirect effect was stronger when college students' optimism and social support were high. This study contributes to student development and self-regulation literature by underscoring that academic performance plays a vital intermediate role in the relationship between self-regulation behaviors and college students' psychological well-being. Besides, we highlight that optimism and social support act as important personal and social resources for college students that can better unleash the positive effects of goal-oriented self-regulation behaviors., Author(s): Huatian Wang [sup.1] , Jinxin Yang [sup.2] , Peikai Li [sup.3] Author Affiliations: (1) grid.6852.9, 0000 0004 0398 8763, Department of Industrial Engineering and Innovation Sciences, Eindhoven University of [...]