Search

The rapid development of electric vehicles has led to a yearly increase in charging load levels， characterized by strong randomness and unpredictability. Therefore， research on load forecasting for charging stations holds significant importance. Firstly， to address the inaccuracy of single-factor forecasting models that only consider load fluctuation trends， this paper analyzes the impact of multiple factors on the accuracy of charging station load forecasting. A load forecasting model is established that takes into account multiple influencing factors and is based on CNN-LSTM （convolutional neural network， long short-term memory）. Subsequently， given the impact of strong randomness of charging load on the model， an error correction method based on the random forest （RF） algorithm is proposed. Finally， the paper conducts simulation verification using real charging station load data as a case study. The research results indicate that the load prediction of the CNN-LSTM model， corrected by the RF algorithm， can accurately cover real values. Compared to the LSTM single model and the non-corrected CNN-LSTM model， it exhibits higher forecasting accuracy and practical value.

This study was designed to investigate the associations among motives and physical activity behaviors and health in urban college students in China. Eight hundred and eighty-seven college students (521 females; M[subscript age] = 20.51, SD = ± 1.67) were recruited from four universities in South and South-central China. Participants' motives (i.e., interest/enjoyment, competence, appearance, fitness, social) toward to physical activity behaviors were measured by the established Motives for Physical Activities Measure (Ryan et al., 1997), while physical activity behaviors were assessed via the validated International Physical Activity Questionnaires for Chinese (Macfarlane et al., 2007). The data were collected in June 2016 and 2017. Participants' total metabolic equivalent (METs) was calculated as the outcome of physical activity behaviors. On average, participants reported 412 METs (SD = 290.82) of physical activity for the prior week. Correlation analysis suggested that all motive components were moderately or highly correlated with one another (r = 0.37 -0.74; p < 0.01), and these variables were significantly, yet modestly, related to physical activity behaviors (r = 0.12 -0.24; p < 0.05). Regression analyses further indicated that the whole model explained 24.5% of the variance [F (5, 394) = 5.02, p < 0.01] when using motives to predict physical activity behaviors. Interestingly, participants' interest/enjoyment was the only significant and positive predictor for their physical activity (ß= 0.23, p < 0.01). Findings suggest that Chinese college students were relatively physically active on a weekly basis. Students' interest/enjoy toward physical activity is a very important motive in promoting physical activity behavior among this population. Health professionals and educators are encouraged to offer a variety of interesting and enjoyable activities for Chinese college students with the goal of helping this population develop and maintain a physically active lifestyle.

Guided by the Transtheoretical Model (Prochaska & DiClemente, 1982), this study investigated the differences of physical activity levels and correlates (i.e., self-efficacy, decisional balance, process of change) across different stages of change levels among Chinese college students. The relationships between students' physical activity correlates and physical activity behavior was also examined. The participants were 887 college students (365 males; M[subscript age] = 20.51, SD = ± 1.67) recruited from four universities in south and south-canter China. Participants completed a battery of established questionnaires assessing their physical activity correlates (self-efficacy, decisional balance, process of change) and 1-week physical activity levels. Results suggested that Chinese college students in the high stage of change group reported significantly higher physical activity levels and correlates than those in the low stage of change group. Pearson correlation analyses suggested that students' self-efficacy was moderately related to other correlates and physical activity behavior. Yet, decisional balance and process of change were only modestly associated with physical activity levels for both groups. Regression analyses further revealed students' self-efficacy emerged as the only significant contributor of their daily PA levels across the two groups. However, decision balance and process of change failed to predict physical activity levels. The implications for practice and direction of future research were discussed.

Practice-based teacher education, as one of the important frameworks for physical education undergraduate curriculum in the USA, has produced effective outcomes. By reviewing the literature on practice-based teacher education, the theoretical connotation and the consciousness of thinking are analyzed. On the basis of the results and experiences since the introduciton of the theory into physical education, the detailed measures were summed up with the application of the theory into the curriculum reform in the USA, with the goal of providing theoretical foundations to support the reform and development of physical education undergraduate programs and teaching ability among pre-service physical education teachers in China. It is concluded that the physical education curriculum in China shall integrate theory into practices. Considering the goal of developing pre-service teachers' teaching skills as the core as well as their technical ability promotion in China, we should follow the principles of the curriculum reform as follows: "practice-based curriculum" as the foundtion, "core teaching skills" as the focus, "coherent and authentic teaching practices" as the guarantee, and "advanced and effective teaching strategies" as the tools. As a result, we can establish a strong academic discipline and program with a deep social impact by producing competitive and high-quality physical education teachers. [ABSTRACT FROM AUTHOR]

Abstract: A brand new method for synthesizing Mn(PO3(OH))·3H2O is attained in this paper. During this process, pure flake-like Mn(PO3(OH))·3H2O precipitate is prepared using C2H5OH as initiator. Besides that, LiMn0.5Fe0.5PO4/C is successfully synthesized from the Mn(PO3(OH))·3H2O precursor at 650 °C for the first time. Thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) are applied in the characterization of the Mn(PO3(OH))·3H2O precursor and LiMn0.5Fe0.5PO4/C. High-resolution transmission electron microscopy (HRTEM) is also used to investigate the morphology of LiMn0.5Fe0.5PO4/C. X-ray photoelectron spectroscopy (XPS) and galvanostatic charge and discharge test are employed to characterize the Mn(PO3(OH))·3H2O precursor and LiMn0.5Fe0.5PO4 material, respectively. The as-prepared LiMn0.5Fe0.5PO4/C material exhibited a reversible capacity of 131 mAh g−1 at 0.05 C. It can be confirmed that the incorporation of Fe into LiMnPO4 can significantly improve the electrochemical properties for improving the conductivity of the material and facilitating the Li+ diffusion. In addition, a capacity of 120 mAh g−1 is still delivered at 0.05 C rate with a capacity retention of about 91% after 25 cycles, and reversible capacity can reach 105 mAh g−1 at 1 C. [Copyright &y& Elsevier]

Abstract: Li1.2+x [Ni0.25Mn0.75]0.8−x O2 (0≤ x ≤4/55) was prepared by a new simple microwave heating method and the effect of extra Li+ content on electrochemistry of Li1.2Ni0.2Mn0.6O2 (x =0) was firstly revealed. X-ray diffraction identified that they had layered α-NaFeO2 structure (space group R-3m). Linear variation of lattice constant as a function of x value supported the formation of solid solution, that is, extra Li+ is possibly incorporated in structure of layered Li1.2Ni0.2Mn0.6O2 (x =0), accompanying oxidization of Ni2+ to Ni3+ to form Li1.2+x [Ni0.25Mn0.75]0.8−x O2 (0≤ x ≤4/55). This was confirmed by X-ray photoelectron spectroscopy that Ni3+ appeared and increased in content with increasing x value. Charge–discharge tests showed that Li1.2+x [Ni0.25Mn0.75]0.8−x O2 (0≤ x ≤4/55) truly displayed different electrochemical properties (different initial charge–discharge plots, capacities and cycleability). Li1.2Ni0.2Mn0.6O2 (x =0) in this work delivered the highest discharge capacity of 219mAhg−1 between 4.8 and 2.0V. Increasing Li content (x value in Li1.2+x [Ni0.25Mn0.75]0.8−x O2) reduced charge–discharge capacities, but significantly enhancing cycleability. [Copyright &y& Elsevier]

The grid-connected operation of the distributed generation (DG) via the direct current (DC) microgrid is the operation mode of the DC power distribution system in the future. Considering the grid-connected operation of multiple DC microgrids, we have proposed a new type of DC power distribution management system aiming at the lowest operating cost of the entire DC power distribution system. Our proposed DC power distribution management system can be used to carry out the optimized dispatching for the connected DC microgrids, thereby achieving the economic, safe, and stable operation of DC power distribution management systems. At the same time, through the different nodes where the modular multilevel converter (MMC) is connected to the alternating current (AC) distribution network, a DC power distribution management system can control the active and reactive power generated by the MMC, achieving the control of the load flow of the upper-stage AC grids in real time. The example simulation shows that the method proposed in this paper has a great role in reducing the transmission losses of the power distribution network, achieving electric power peak-load shifting, and utilizing renewable energy. Thus, it can not only maximize the use of distributed renewable resources, but also enable mutual support and optimal scheduling between a DC power distribution system and multiple microgrids. [ABSTRACT FROM AUTHOR]