There are often system. The high measure many inter-harmonics in power t accuracy of inter-harmonics order, amplitude and initial phase is needed. A new approach is presented for inter-harmonic modeling and parameter ...There are often system. The high measure many inter-harmonics in power t accuracy of inter-harmonics order, amplitude and initial phase is needed. A new approach is presented for inter-harmonic modeling and parameter estimation based on linear support vector machine （SVM）. Firstly, parameter estimation of linear model is realized based on standard linear SVM. Then, interharmonic model is transformed to a linear model according to trigonometric functions. The approach obtains order of inter-harmonic model with windowed Blackman-Tukey （BT） spectrum analysis, and gets number and frequency of harmonics. Finally, the linear SVM is applied to estimate the inter-harmonic parameters, amplitude and initial phase. The simulation results show that the proposed approach has high precision and good antinoise. The accuracy of three parameters are all higher than 98%.展开更多
A design of a rotating condenser is suggested. The maximum radius under the effect of rotation is estimated analytically .It is found that it decreases with the angular velocity. This in turn increases the rate of swe...A design of a rotating condenser is suggested. The maximum radius under the effect of rotation is estimated analytically .It is found that it decreases with the angular velocity. This in turn increases the rate of sweeping the surface by departing droplets. The appearance of droplets with smaller radii will be predominant. These small droplets offer small thermal resistances, thus enhancing heat transfer through the condenser surface. It is found also that the maximum radius is a function of the distance from the axis of the rotating condenser. Thus the value of the maximum radius under rotation is not unique. This in turn makes the heat flux through the condenser surface not to be uniform.展开更多
In order to provide scientific support to policy makers in the regulation of PM2.5 pollution in China, it is important to accurately assess the current status, spatiotemporal characteristics and regionalization data f...In order to provide scientific support to policy makers in the regulation of PM2.5 pollution in China, it is important to accurately assess the current status, spatiotemporal characteristics and regionalization data for this air pollutant. An analysis of the pollution status of PM2.5 was conducted using daily averaged mass concentration data recorded in 74 cities in 2013 and 161 cities in 2014. The rotated empirical orthogonal function(REOF) method was applied to analyze this data. Results showed that the average annual PM2.5 concentration in urban areas of China is 62.2±21.5 ?g/m3, and that the distribution is spatially heterogeneous. The North China Plain, middle and lower Yangtze River Plain, Sichuan Basin and Guanzhong Plain had relatively high annual PM2.5 concentrations compared with the southeast coastal region, the Tibetan Plateau and the Yungui Plateau. PM2.5 mass concentrations tended to be higher in winter than in summer, however, the data for many cities showed a small peak in concentrations from May to July. An analysis of the spatial correlation of PM2.5 indicated a significant influence of topographic conditions. A lower correlation was observed where terrain features varied greatly. Based on the results of the REOF analysis and topographic characteristics, ten regions were identified in mid-eastern China, which could be considered as basic pollution prevention divisions for PM2.5; these include the North China Plain region, Pearl River Delta region, Jianghuai Plain region, middle Yangtze River Plain region, Northeast Plain region, Jiangnan coastal region, Sichuan Basin region, Qiantao Plain region, Guanzhong-Central Plain region and Yungui Plateau region. Seasonal variations in the regionalization data were observed, especially for the North China Plain and Pearl River Delta regions. Among the ten regions identified in this study, the North China Plain, Guanzhong-Central Plain, middle Yangtze River Plain and Jianghuai Plain had relatively high PM2.5 mass concentrations in comparison with the others. Therefore, these regions should be considered as the key regions to target in developing PM2.5 pollution prevention strategies. This study improves the present understanding of the spatial distribution, seasonal changes and regional status of PM2.5 pollution in China and helps establish possible control strategies for the reduction of this air pollutant.展开更多
基金National Natural Science Foundation of China(No.60774011)Natural Science Foundation of zhejiang Province,China(No.Y1090182)
文摘There are often system. The high measure many inter-harmonics in power t accuracy of inter-harmonics order, amplitude and initial phase is needed. A new approach is presented for inter-harmonic modeling and parameter estimation based on linear support vector machine （SVM）. Firstly, parameter estimation of linear model is realized based on standard linear SVM. Then, interharmonic model is transformed to a linear model according to trigonometric functions. The approach obtains order of inter-harmonic model with windowed Blackman-Tukey （BT） spectrum analysis, and gets number and frequency of harmonics. Finally, the linear SVM is applied to estimate the inter-harmonic parameters, amplitude and initial phase. The simulation results show that the proposed approach has high precision and good antinoise. The accuracy of three parameters are all higher than 98%.
文摘A design of a rotating condenser is suggested. The maximum radius under the effect of rotation is estimated analytically .It is found that it decreases with the angular velocity. This in turn increases the rate of sweeping the surface by departing droplets. The appearance of droplets with smaller radii will be predominant. These small droplets offer small thermal resistances, thus enhancing heat transfer through the condenser surface. It is found also that the maximum radius is a function of the distance from the axis of the rotating condenser. Thus the value of the maximum radius under rotation is not unique. This in turn makes the heat flux through the condenser surface not to be uniform.
基金supported by the Special Funds of the State Environmental Protection Public Welfare Industry(201509001,201309016)the Transformation Project of China National Environmental Monitoring Center(2011ZX-010-001)
文摘In order to provide scientific support to policy makers in the regulation of PM2.5 pollution in China, it is important to accurately assess the current status, spatiotemporal characteristics and regionalization data for this air pollutant. An analysis of the pollution status of PM2.5 was conducted using daily averaged mass concentration data recorded in 74 cities in 2013 and 161 cities in 2014. The rotated empirical orthogonal function(REOF) method was applied to analyze this data. Results showed that the average annual PM2.5 concentration in urban areas of China is 62.2±21.5 ?g/m3, and that the distribution is spatially heterogeneous. The North China Plain, middle and lower Yangtze River Plain, Sichuan Basin and Guanzhong Plain had relatively high annual PM2.5 concentrations compared with the southeast coastal region, the Tibetan Plateau and the Yungui Plateau. PM2.5 mass concentrations tended to be higher in winter than in summer, however, the data for many cities showed a small peak in concentrations from May to July. An analysis of the spatial correlation of PM2.5 indicated a significant influence of topographic conditions. A lower correlation was observed where terrain features varied greatly. Based on the results of the REOF analysis and topographic characteristics, ten regions were identified in mid-eastern China, which could be considered as basic pollution prevention divisions for PM2.5; these include the North China Plain region, Pearl River Delta region, Jianghuai Plain region, middle Yangtze River Plain region, Northeast Plain region, Jiangnan coastal region, Sichuan Basin region, Qiantao Plain region, Guanzhong-Central Plain region and Yungui Plateau region. Seasonal variations in the regionalization data were observed, especially for the North China Plain and Pearl River Delta regions. Among the ten regions identified in this study, the North China Plain, Guanzhong-Central Plain, middle Yangtze River Plain and Jianghuai Plain had relatively high PM2.5 mass concentrations in comparison with the others. Therefore, these regions should be considered as the key regions to target in developing PM2.5 pollution prevention strategies. This study improves the present understanding of the spatial distribution, seasonal changes and regional status of PM2.5 pollution in China and helps establish possible control strategies for the reduction of this air pollutant.
