Abstract： To enable the use of metallic components in direct methanol fuel cells （DMFCs）, issues related to corrosion resistance must be considered because of an acid environment induced by the solid electrolyte. I...Abstract： To enable the use of metallic components in direct methanol fuel cells （DMFCs）, issues related to corrosion resistance must be considered because of an acid environment induced by the solid electrolyte. In this study, we report the electrochemical behaviors of metal-fiber-based porous sintered components in a simulated corrosive environment of DMFCs. Three materials were evaluated： pure copper, AISI304, and AISI316L. The environmental factors and related mechanisms affecting the corrosion behaviors were analyzed. The results demonstrated that AISI316L exhibits the best performance. A higher SO4^2- concentration increases the risk of material corrosion, whereas an increase in methanol concentration inhibits corrosion. The morphological features of the corroded samples were also characterized in this study.展开更多
Using input, output and pollution data of industrial enterprises in 30 Chinese provinces and municipalities from 1998 to 2005, this paper creates an environmental production frontier function model to assess China'...Using input, output and pollution data of industrial enterprises in 30 Chinese provinces and municipalities from 1998 to 2005, this paper creates an environmental production frontier function model to assess China's industrial growth sources, particularly environmental control and changes in the industrial environmental structure's impact on industrial productivity. It found that (1) at its current stage, China's rapid industrial growth is accompanied by a slow increase in pollution; (2) environmental total factor productivity has become a primary driver of rapid growth with less pollution; (3) environmental control didn't cause any substantial restraint on China's industrial growth; (4) improvement in industrial environmental structure contributes an increasingly large share to economic growth with less pollution. China's industrial productivity is increasing, its growth model is being transformed, and the environment is exerting a diminishing constraint on economic growth.展开更多
Objective To evaluate the environmental and technical efficiencies of China＇s industrial sectors and provide appropriate advice for policy makers in the context of rapid economic growth and concurrent serious environ...Objective To evaluate the environmental and technical efficiencies of China＇s industrial sectors and provide appropriate advice for policy makers in the context of rapid economic growth and concurrent serious environmental damages caused by industrial pollutants. Methods A data of envelopment analysis （DEA） framework crediting both reduction of pollution outputs and expansion of good outputs was designed as a model to compute environmental efficiency of China＇s regional industrial systems. Results As shown by the geometric mean of environmental efficiency, if other inputs were made constant and good outputs were not to be improved, the air pollution outputs would have the potential to be decreased by about 60% in the whole China. Conclusion Both environmental and technical efficiencies have the potential to be greatly improved in China, which may provide some advice for policy-makers.展开更多
This study mainly investigates the environmental efficiency of 267 Chinese cities from 2004 to 2012 through a metafrontier,directional and super-efficiency approach. First,we explore the regional and time heterogeneit...This study mainly investigates the environmental efficiency of 267 Chinese cities from 2004 to 2012 through a metafrontier,directional and super-efficiency approach. First,we explore the regional and time heterogeneity of environmental efficiency. Then,we compare the technological gap ratio in different regions and years. Lastly,we analyze the technological and management potential in different regions. We determine that the gap between environmental efficiency under group frontier and metafrontier widened from 2009 to 2012,indicating that environmental efficiency varies in different regions in China. The technology gap ratio has decreased in the four regions. This result confirms that the regional heterogeneity of environmental efficiency has increased. Thus,strengthening environmental management is crucial. China must improve green innovation to decrease energy consumption and abate carbon emissions.展开更多
Direct Expansion Ground Source Heat Pump (DXGSHP) system directly extracts heat or cold energy from ground by consuming electricity to provide for space conditioning. Compared with the currently widely-used secondary ...Direct Expansion Ground Source Heat Pump (DXGSHP) system directly extracts heat or cold energy from ground by consuming electricity to provide for space conditioning. Compared with the currently widely-used secondary loop Ground Couple Heat Pump (GCHP) system, it has higher energy efficiency, lower operating costs, and less environmental impact. A case study is carried out in this paper. The subject is a residential building located in Beijing, China. It is assumed that the building adopts the DXGSHP system and the GCHP system respectively. Annual loads and energy consumption are simulated and computed. Then the initial cost, operating cost and CO2 emission are calculated. The economic benefit is analyzed with the Payback Time method and the Dynamic Annual Cost Value method. The environmental benefit is discussed mainly by comparing the CO2 emission savings. The results show that the DXGSHP system has higher initial costs, but lower operating costs, and less greenhouse gas emissions. The DXGSHP system has better comprehensive benefits than the GCHP system.展开更多
为了研究考虑高海拔多环境因素影响下输电线路可听噪声的预测问题,在海拔2400 m高度点的500 kV同塔双回线路下,搭建了边相外20、30、35 m三处可听噪声观测站,同时利用气象站进行多环境因素指标的数据采集。文中提出了一种基于多头注意...为了研究考虑高海拔多环境因素影响下输电线路可听噪声的预测问题,在海拔2400 m高度点的500 kV同塔双回线路下,搭建了边相外20、30、35 m三处可听噪声观测站,同时利用气象站进行多环境因素指标的数据采集。文中提出了一种基于多头注意力机制(multi⁃head attention,MHA)的卷积神经网络(convolutional neural network,CNN)—双向长短期记忆网络(bi⁃directional long short term memory,BiLSTM)模型进行可听噪声预测。首先,采用皮尔逊相关性分析对多种环境因素数据进行相关程度计算比较与剔除;然后,为充分挖掘可听噪声数据中的时序特征,使用CNN对多环境因素数据进行特征提取;再将提取的特征向量输入到BiLSTM中进行训练,并通过在BiLSTM端引入多头注意力机制,使模型学习权重更高的数据特征,从而提升模型预测精度;结果表明,该方法构建的组合模型可以提升考虑多因素特征可听噪声数据的预测精度,且具有较好的泛化性。展开更多
基金financially supported by the Natural Science Foundation of Guangdong Province, China (No. S2013040016899)the Fundamental Research Funds for Central Universities of China (No. 2013ZM0003)+1 种基金the National Natural Science Foundation of China (No. 51275180)the Open Fund of Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures (No. 2013001)
文摘Abstract： To enable the use of metallic components in direct methanol fuel cells （DMFCs）, issues related to corrosion resistance must be considered because of an acid environment induced by the solid electrolyte. In this study, we report the electrochemical behaviors of metal-fiber-based porous sintered components in a simulated corrosive environment of DMFCs. Three materials were evaluated： pure copper, AISI304, and AISI316L. The environmental factors and related mechanisms affecting the corrosion behaviors were analyzed. The results demonstrated that AISI316L exhibits the best performance. A higher SO4^2- concentration increases the risk of material corrosion, whereas an increase in methanol concentration inhibits corrosion. The morphological features of the corroded samples were also characterized in this study.
基金support by National Fund for Social Sciences (Project Number: 07BJY019 and 2008AJY032)Cultural and Social Sciences Fund of the Ministry of Education (Project Number: 2008JYJ059)the financial support by New Century Talent Support Program of the Ministry of Education
文摘Using input, output and pollution data of industrial enterprises in 30 Chinese provinces and municipalities from 1998 to 2005, this paper creates an environmental production frontier function model to assess China's industrial growth sources, particularly environmental control and changes in the industrial environmental structure's impact on industrial productivity. It found that (1) at its current stage, China's rapid industrial growth is accompanied by a slow increase in pollution; (2) environmental total factor productivity has become a primary driver of rapid growth with less pollution; (3) environmental control didn't cause any substantial restraint on China's industrial growth; (4) improvement in industrial environmental structure contributes an increasingly large share to economic growth with less pollution. China's industrial productivity is increasing, its growth model is being transformed, and the environment is exerting a diminishing constraint on economic growth.
文摘Objective To evaluate the environmental and technical efficiencies of China＇s industrial sectors and provide appropriate advice for policy makers in the context of rapid economic growth and concurrent serious environmental damages caused by industrial pollutants. Methods A data of envelopment analysis （DEA） framework crediting both reduction of pollution outputs and expansion of good outputs was designed as a model to compute environmental efficiency of China＇s regional industrial systems. Results As shown by the geometric mean of environmental efficiency, if other inputs were made constant and good outputs were not to be improved, the air pollution outputs would have the potential to be decreased by about 60% in the whole China. Conclusion Both environmental and technical efficiencies have the potential to be greatly improved in China, which may provide some advice for policy-makers.
文摘This study mainly investigates the environmental efficiency of 267 Chinese cities from 2004 to 2012 through a metafrontier,directional and super-efficiency approach. First,we explore the regional and time heterogeneity of environmental efficiency. Then,we compare the technological gap ratio in different regions and years. Lastly,we analyze the technological and management potential in different regions. We determine that the gap between environmental efficiency under group frontier and metafrontier widened from 2009 to 2012,indicating that environmental efficiency varies in different regions in China. The technology gap ratio has decreased in the four regions. This result confirms that the regional heterogeneity of environmental efficiency has increased. Thus,strengthening environmental management is crucial. China must improve green innovation to decrease energy consumption and abate carbon emissions.
文摘Direct Expansion Ground Source Heat Pump (DXGSHP) system directly extracts heat or cold energy from ground by consuming electricity to provide for space conditioning. Compared with the currently widely-used secondary loop Ground Couple Heat Pump (GCHP) system, it has higher energy efficiency, lower operating costs, and less environmental impact. A case study is carried out in this paper. The subject is a residential building located in Beijing, China. It is assumed that the building adopts the DXGSHP system and the GCHP system respectively. Annual loads and energy consumption are simulated and computed. Then the initial cost, operating cost and CO2 emission are calculated. The economic benefit is analyzed with the Payback Time method and the Dynamic Annual Cost Value method. The environmental benefit is discussed mainly by comparing the CO2 emission savings. The results show that the DXGSHP system has higher initial costs, but lower operating costs, and less greenhouse gas emissions. The DXGSHP system has better comprehensive benefits than the GCHP system.
文摘为了研究考虑高海拔多环境因素影响下输电线路可听噪声的预测问题,在海拔2400 m高度点的500 kV同塔双回线路下,搭建了边相外20、30、35 m三处可听噪声观测站,同时利用气象站进行多环境因素指标的数据采集。文中提出了一种基于多头注意力机制(multi⁃head attention,MHA)的卷积神经网络(convolutional neural network,CNN)—双向长短期记忆网络(bi⁃directional long short term memory,BiLSTM)模型进行可听噪声预测。首先,采用皮尔逊相关性分析对多种环境因素数据进行相关程度计算比较与剔除;然后,为充分挖掘可听噪声数据中的时序特征,使用CNN对多环境因素数据进行特征提取;再将提取的特征向量输入到BiLSTM中进行训练,并通过在BiLSTM端引入多头注意力机制,使模型学习权重更高的数据特征,从而提升模型预测精度;结果表明,该方法构建的组合模型可以提升考虑多因素特征可听噪声数据的预测精度,且具有较好的泛化性。
