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Journal of Thermal Science 2024年第4期33卷 1577-1589页

作者： chen chengdai WANG changhong ZHENG Zijun School of Materials and Energy Guangdong University of Technology

The effective cathode flow field design can realize the internal water balance and higher current density output of proton exchange membrane fuel cells(PEMFC).Therefore,a segmented water management flow field is proposed in this study,i.e.a half separated-half coupled cathode(HSHC) flow field which has two inlets but just one outlet.A 3D numerical PEMFC model is applied to study the effect of the HSHC flow field on PEMFC performance and its operating strategy in terms of operating conditions.The study results are shown as follows:Compared with the two conventional cathode flow fields,the HSHC flow field improves the water balance along the channel and increases the current density by 17.1% at a cathode stoichiometry of 3.25.It is because the HSHC flow field can overcome the water loss at channels upstream and the water accumulation at channels downstream.The draw water phenomenon(DWP) in the HSHC flow field is observed,which is mainly affected by the water vapor pressure of channel.Based on the DWP,cooling channel inlet flow rates can be used to adjust water balance,but severe water loss should be avoided.In addition,the inlet temperature control in HSHC flow field should be that cell temperature>cathode channel inlet temperature>cooling channel inlet temperature> ambient temperatures for better water balance.

关键词： proton exchange membrane fuel cells channel design segmented water management water balance operating strategy

Construction and Application of a Regional Kilometer-Scale Carbon Source and Sink Assimilation Inversion System(CCMVS-R)

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Engineering 2024年第2期33卷 263-275页

作者： Lifeng Guo Xiaoye Zhang Junting Zhong Deying Wang changhong Miao Licheng Zhao Zijiang Zhou Jie Liao Bo Hu Lingyun Zhu Yan chen Monitoring and Assessment Center for GHGs and Carbon Neutrality&Key Laboratory of Atmospheric Chemistry of CMA Chinese Academy of Meteorological SciencesBeijing 100081China Laboratory of Climate Change Mitigation and Carbon Neutrality Henan UniversityZhengzhou 450001China National Meteorological Information Center Beijing 100081China Shanxi Meteorological Administration Taiyuan 030002China Shanxi Provincial Institute of Meteorological Sciences Taiyuan 030002China Jiangsu Provincial Climate Center Nanjing 210000China

CO_(2)is one of the most important greenhouse gases(GHGs)in the earth’s atmosphere.Since the industrial era,anthropogenic activities have emitted excessive quantities of GHGs into the atmosphere,resulting in climate warming since the 1950s and leading to an increased frequency of extreme weather and climate events.In 2020,China committed to striving for carbon neutrality by 2060.This commitment and China’s consequent actions will result in significant changes in global and regional anthropogenic carbon emissions and therefore require timely,comprehensive,and objective monitoring and verification support(MVS)systems.The MVS approach relies on the top-down assimilation and inversion of atmospheric CO_(2)concentrations,as recommended by the Intergovernmental Panel on Climate Change(IPCC)Inventory Guidelines in 2019.However,the regional high-resolution assimilation and inversion method is still in its initial stage of development.Here,we have constructed an inverse system for carbon sources and sinks at the kilometer level by coupling proper orthogonal decomposition(POD)with four-dimensional variational(4DVar)data assimilation based on the weather research and forecasting-greenhouse gas(WRF-GHG)model.Our China Carbon Monito ring and Verification Support at the Regional level(CCMVS-R)system can continuously assimilate information on atmospheric CO_(2)and other related information and realize the inversion of regional and local anthropogenic carbon emissions and natural terrestrial ecosystem carbon exchange.Atmospheric CO_(2)data were collected from six ground-based monito ring sites in Shanxi Province,China to verify the inversion effect of regio nal anthropogenic carbon emissions by setting ideal and real experiments using a two-layer nesting method(at 27 and 9 km).The uncertainty of the simulated atmospheric CO_(2)decreased significantly,with a root-mean-square error of CO_(2)concentration values between the ideal value and the simulated after assimilation was close to 0.The total anthropogenic carbon emissions in S

关键词： CCMVS-R Regional carbon assimilation system Anthropogenic carbon emissions CO_(2) POD 4DVar

Interface phonon polariton coupling to enhance grapheneabsorption

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Frontiers of Optoelectronics 2021年第4期14卷 445-449页

作者： Zhenyao chen Junjie MEI Ye ZHANG Jishu TAN Qing XIONG changhong chen Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China

Here we present a graphene photodetector ofwhich the graphene and structural system infraredabsorptions are enhanced by interface phonon polariton(IPhP) coupling. IPhPs are supported at the SiC/AlNinterface of device structure and used to excite interbandtransitions of the intrinsic graphene under gated-fieldtuning. The simulation results show that at normalincidence the absorbance of graphene or system reachesup to 43% or closes to unity in a mid-infrared frequencyrange. In addition, we found the peak-absorption frequencyis mainly decided by the AlN thickness, and it has ared-shift as the thickness decreases. This structure has greatapplication potential in graphene infrared detectiontechnology.

关键词： interface phonon polariton(IPhP) infrared absorption enhancement graphene photodetector

对创新链产业链资金链人才链“四链”融合发展的问题研究

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中国科学院院刊 2024年第2期39卷 262-269页

作者：聂常虹赵斐杰李钏陈彤中国科学院大学经济与管理学院北京100190 中国科学院科技创新发展中心北京100190 中国科学院数学与系统科学研究院北京100190

推动创新链产业链资金链人才链(以下简称“四链”)深度融合对经济高质量发展的重要意义不言而喻,其本质是降低创新要素跨组织边界流动时遇到的各类壁垒,提升配置效率,更好发挥企业的科技创新主体作用,增强国家创新体系整体效能。文章在... 详细信息

推动创新链产业链资金链人才链(以下简称“四链”)深度融合对经济高质量发展的重要意义不言而喻,其本质是降低创新要素跨组织边界流动时遇到的各类壁垒,提升配置效率,更好发挥企业的科技创新主体作用,增强国家创新体系整体效能。文章在系统分析我国“四链”融合问题基础上,提出以下对策建议:(1)推动科技创新政策体系化布局和系统性落实;(2)探索建设“大科技中介机构”,构建符合创新规律的议事决策机制和市场化定价机制;(3)加快推进科技成果转化实施细则制定,明确责权利边界;(4)围绕产业链和创新链发展需求,前瞻性部署建设人才链;(5)强化财税政策对科技创新的支撑作用;(6)加强应用场景创新,助力提高国产新技术、新产品的市场接受度。

关键词：创新链产业链资金链人才链国家创新体系

Do vehicular emissions dominate the source of C6–C8 aromatics in the megacity Shanghai of eastern China?

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Journal of Environmental Sciences 2015年第1期27卷 290-297页

作者： Hongli Wang Qian Wang Jianmin chen changhong chen cheng Huang Liping Qiao Shengrong Lou Jun Lu Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3) Department of Environmental Science and EngineeringFudan University State Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex Shanghai Academy of Environmental Sciences

The characteristic ratios of volatile organic compounds（VOCs） to i-pentane, the indicator of vehicular emissions, were employed to apportion the vehicular and non-vehicular contributions to reactive species in urban Shanghai. Two kinds of tunnel experiments, one tunnel with more than 90% light duty gasoline vehicles and the other with more than 60% light duty diesel vehicles, were carried out to study the characteristic ratios of vehicle-related emissions from December 2009 to January 2010. Based on the experiments, the characteristic ratios of C6–C8aromatics to i-pentane of vehicular emissions were 0.53 ± 0.08（benzene）, 0.70 ± 0.12（toluene）,0.41 ± 0.09（m,p-xylenes）, 0.16 ± 0.04（o-xylene）, 0.023 ± 0.011（styrene）, and 0.15 ± 0.02（ethylbenzene）, respectively. The source apportionment results showed that around 23.3% of C6–C8 aromatics in urban Shanghai were from vehicular emissions, which meant that the non-vehicular emissions had more importance. These findings suggested that emission control of non-vehicular sources, i.e. industrial emissions, should also receive attention in addition to the control of vehicle-related emissions in Shanghai. The chemical removal of VOCs during the transport from emissions to the receptor site had a large impact on the apportionment results. Generally, the overestimation of vehicular contributions would occur when the VOC reaction rate constant with OH radicals（k OH） was larger than that of the vehicular indicator, while for species with smaller k OH than the vehicular indicator, the vehicular contribution would be underestimated by the method of characteristic ratios.

关键词： Aromatics Characteristic ratio Vehicular emissions Non-vehicular emissions Shanghai

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波束开角对多普勒测频结果的影响

应用声学 2024年第1期43卷 40-46页

作者：陈茁王长红邓锴中国科学院声学研究所北京100190 中国科学院大学北京100049 北京市海洋声学装备工程技术研究中心北京100190

具有不同波束开角的声学多普勒测速设备未标定的测速结果存在偏差。基于水底椭圆散射模型研究了波束开角对声学多普勒测速结果的影响,对提高声学测速性能具有实际意义。水底椭圆散射模型下,足印上不同方位传播损失和散射强度存在差异,... 详细信息

具有不同波束开角的声学多普勒测速设备未标定的测速结果存在偏差。基于水底椭圆散射模型研究了波束开角对声学多普勒测速结果的影响,对提高声学测速性能具有实际意义。水底椭圆散射模型下,足印上不同方位传播损失和散射强度存在差异,导致频谱不对称,测频结果偏小。利用不对称系数量化频谱不对称程度,若波束开角增大,方位不对称系数随之增大,测频偏差增大,推导了波束开角导致的测频偏差解析式。分析仿真和外场试验数据测频结果可知,不同多普勒频移下测频偏差和理论计算值相符,不同波束开角下实际测频偏差与理论公式计算的测频偏差均随波束开角增大而增大。

关键词：宽带多普勒测速波束开角误差分析

Observation-based sources evolution of non-methane hydrocarbons (NMHCs) in a megacity of China

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Journal of Environmental Sciences 2023年第2期124卷 794-805页

作者： Yarong Peng Hongli Wang Qian Wang Shengao Jing Jingyu An Yaqin Gao cheng Huang Rusha Yan Haixia Dai Tiantao cheng Qiang Zhang Meng Li Jianlin Hu Zhihao Shi Li Li Shengrong Lou Shikang Tao Qinyao Hu Jun Lu changhong chen Department of Environmental Science and Engineering Shanghai Key Laboratory of Atmospheric Particle Pollution and PreventionInstitute of Atmospheric SciencesFudan UniversityShanghai 200438China State Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex Shanghai Academy of Environmental SciencesShanghai 200233China Department of Atmospheric and Oceanic Sciences Institute of Atmospheric SciencesFudan UniversityShanghai 200438China Department of Earth System Science Ministry of Education Key Laboratory for Earth System ModelingTsinghua UniversityBeijing 100084China Big Data Institute for Carbon Emission and Environmental Pollution Fudan UniversityShanghai 200438China School of Environmental Science and Engineering Nanjing University of Information Science&TechnologyNanjing 210044China

Both concentrations and emissions of many air pollutants have been decreasing due to implement of control measures in China,in contrast to the fact that an increase in emissions of non-methane hydrocarbons(NMHCs)has been reported.This study employed seven years continuous NMHCsmeasurements and the related activities data of Shanghai,a megacity in China,to explore evolution of emissions and effectiveness of air pollution control measures.The mixing ratio of NMHCs showed no statistical interannual changes,of which their compositions exhibited marked changes.This resulted in a decreasing trend of ozone formation potential by 3.8%/year(p<0.05,the same below),which should be beneficial to ozone pollution mitigation as its production in Shanghai is in the NMHCs-limited regime.Observed alkanes,aromatics and acetylene changed by+3.7%/year,-5.9%/year and-7.4%/year,respectively,and alkenes showed no apparent trend.NMHCs sources were apportioned by a positive matrix factorization model.Accordingly,vehicular emissions(-5.9%/year)and petrochemical industry emissions(-7.1%/year)decreased significantly,but the decrease slowed down;significant reduction in solvent usage(-9.0%/year)appeared after 2010;however,emissions of natural gas(+12.6%/year)and fuel evaporation(with an increasing fraction)became more important.The inconsistency between observations and inventories was found in interannual trend and speciation as well as source contributions,emphasizing the need for further validation in NMHCs emission inventory.Our study confirms the effectiveness of measures targeting mobile and centralized emissions from industrial sources and reveals a need focusing on fugitive emissions,which provided new insights into future air policies in polluted region.

关键词： Characteristics Source apportionment Observation-based Interannual trend Shanghai

全龄友好社区视角下老旧社区公共空间更新策略——以南昌市梨园西社区为例

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规划师 2024年第2期40卷 106-114页

作者：李小云张玉陈长虹江西师范大学城市建设学院江西师范大学城乡规划系自然资源部大湖流域国土空间生态保护修复工程技术创新中心江西省国土空间调查规划研究院

当前,老旧社区公共空间供需矛盾突出,基于全龄友好社区视角,从广场公园、街道、宅间等3个层面提出老旧社区公共空间全龄化更新策略,并以南昌市梨园西社区为例进行更新实践,通过环境品质提升,促进老旧社区公共空间代际互动与融合的实现,... 详细信息

当前,老旧社区公共空间供需矛盾突出,基于全龄友好社区视角,从广场公园、街道、宅间等3个层面提出老旧社区公共空间全龄化更新策略,并以南昌市梨园西社区为例进行更新实践,通过环境品质提升,促进老旧社区公共空间代际互动与融合的实现,为类似社区公共空间更新提供参考。

关键词：全龄友好社区老旧社区公共空间更新策略

Ozone sensitivity analysis with the MM5-CMAQ modeling system for Shanghai

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Journal of Environmental Sciences 2011年第7期23卷 1150-1157页

作者： Li Li changhong chen cheng Huang Haiying Huang Gangfeng Zhang Yangjun Wang Minghua chen Hongli Wang Yiran chen D. G. Streets Jiamo Fu Institute of Environmental Pollution and Health School of Environmental and Chemical Engineering Shanghai University Shanghai 200444 China Shanghai Academy of Environmental Sciences Shanghai 200233 China Decision and Information Sciences Division Argonne National Laboratory Argonne IL 60439 USA

Ozone has become one of the most important air pollution issues around the world. This article applied both O 3 /（NOy-NOx） and H 2 O 2 /HNO 3 indicators to analyze the ozone sensitivity in urban and rural areas of Shanghai, with implementation of the MM5-CMAQ modeling system in July, 2007. The meteorological parameters were obtained by using the MM5 model. A regional emission inventory with spatial and temporal allocation based on the statistical data has been developed to provide input emission data to the MM5-CMAQ modeling system. Results showed that the ozone concentrations in Shanghai show clear regional differences. The ozone concentration in rural areas was much higher than that in the urban area. Two indicators showed that ozone was more sensitive to VOCs in urban areas, while it tended to be NOx sensitive in rural areas of Shanghai.

关键词： ozone sensitivity indicators Shanghai

Ultrafine particle emission characteristics of diesel engine by on-board and test bench measurement

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Journal of Environmental Sciences 2012年第11期24卷 1972-1978页

作者： cheng Huang Diming Lou Zhiyuan Hu Piqiang Tai Di Yao Wei Hu Peng Li Jin Ren changhong chen School of Automobile Studies Tongji UniversityShanghai 201804China Shanghai Academy of Environmental Sciences Shanghai 200233China

This study investigated the emission characteristics of ultra.fine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engine to be in the range of （0.56-8.35）×10^8 cm^-3. The on-board measurement results illustrated that the ultra_fine particles were strongly correlated with changes in real-world driving cycles. The particle number concentration was down to 2.0 ×10^6 cm^-3 and 2.7 ×10^7 cm^-3 under decelerating and idling operations and as high as 5.0×10^8 cm^-3 under accelerating operation. It was also indicated that the particle number measured by the two methods increased with the growth of engine load at each engine speed in both cases. The particle number presented a ＂U＂ shaped distribution with changing speed at high engine load conditions, which implies that the particle number will reach its lowest level at medium engine speeds. The particle sizes of both measurements showed single mode distributions. The peak of particle size was located at about 50-80 nm in the accumulation mode particle range. Nucleation mode particles will significantly increase at low engine load operations like idling and decelerating caused by the high concentration of unburned organic compounds.

关键词： ultrafine particle emission emission factor diesel engine on-board emission measurement TSI EEPS