为研究阻尼钢轨的减振降噪性能,以标准钢轨和迷宫式约束阻尼钢轨为研究对象,通过在消声室内测试标准钢轨和迷宫式约束阻尼钢轨的振动与噪声特性,实验结果表明：阻尼钢轨具有良好的减振降噪效果,阻尼钢轨在全频段内有效地抑制振动和噪声...为研究阻尼钢轨的减振降噪性能,以标准钢轨和迷宫式约束阻尼钢轨为研究对象,通过在消声室内测试标准钢轨和迷宫式约束阻尼钢轨的振动与噪声特性,实验结果表明：阻尼钢轨具有良好的减振降噪效果,阻尼钢轨在全频段内有效地抑制振动和噪声。在径向冲击荷载下,迷宫式约束阻尼钢轨相对于标准钢轨的振动加速度衰减量为5%~19%,振动时间衰减量都大于94%,总噪声级降低达9 d B以上;在轴向的冲击荷载下,迷宫式约束阻尼钢轨相对于标准钢轨的振动加速度衰减量为9%~21%,振动时间衰减量都大于92%,总噪声级降低达5 d B以上。实验结果为新型约束阻尼钢轨的优化设计提供了更加准确的实验依据。展开更多
Samples of roadside dust were collected from 30 sites in Hong Kong.The total concentrations of 10 metals in the samples were analyzed,and the correlation coefficients among the metal contents and the annual average da...Samples of roadside dust were collected from 30 sites in Hong Kong.The total concentrations of 10 metals in the samples were analyzed,and the correlation coefficients among the metal contents and the annual average daily traffic(AADT)in 1986 were determined.Pb was found to have a significant correlation(P<0.01)with AADT.No correlation was found between Al, Ba,Cd,Cr,Cu,Fe,Mn,Ni,and Zn with respect to AADT.A general decrease in the level of Pb in roadside dust in the past few years has been observed since the reduction in the level of lead in petrol.1989 Academic Press,Inc.展开更多
Ammonia(NH_(3))is an important raw material for modern agriculture and industry,being widely demanded to sustain the sustainable development of modern society.Currently,the industrial production methods of NH_(3),such...Ammonia(NH_(3))is an important raw material for modern agriculture and industry,being widely demanded to sustain the sustainable development of modern society.Currently,the industrial production methods of NH_(3),such as the traditional Haber-Bosch process,have drawbacks including high energy consumption and significant carbon dioxide emissions.In recent years,the electrocatalytic nitrate reduction reaction(NO_(3)RR)powered by intermittent renewable energy sources has gradually become a multidisciplinary research hotspot,as it allows for the efficient synthesis of NH_(3)under mild conditions.In this review,we focus on the research of electrocatalysts with atomic-level site,which have attracted attention due to their extremely high atomic utilization efficiency and unique structural characteristics in the field of NO_(3)RR.Firstly,we introduce the mechanism of nitrate reduction for ammonia synthesis and discuss the in-situ characterization techniques related to the mechanism study.Secondly,we review the progress of the electrocatalysts with atomic-level site for nitrate reduction and explore the structure-activity relationship to guide the rational design of efficient catalysts.Lastly,the conclusions of this review and the challenges and prospective of this promising field are presented.展开更多
Global warming and climate change significantly increase the frequency of coastal floods caused by sea level rise(SLR) as a permanent factor and hydrometeorological hazards as tentative factors. The combined risks wil...Global warming and climate change significantly increase the frequency of coastal floods caused by sea level rise(SLR) as a permanent factor and hydrometeorological hazards as tentative factors. The combined risks will affect coastal communities.South Korea is gradually facing SLR risks, mainly in its southern coastal regions;however, disaster risk reduction(DRR)in coastal regions remains fragmented. This study aimed to investigate the status of DRR for coastal communities in South Korea by looking at government practices and testimonies from residents. This study reviewed DRR-related regulations and documents and collected data from interviews with local government officials, field visits, and informal conversations with residents in six coastal communities. The findings show that the coastal communities were less resilient to coastal floods than to other hazards, such as typhoons and heavy rains, and the potential consequences could be expanded due to demographic challenges, fragmented institutional systems, and low risk awareness. Moreover, this study emphasized the necessity of an integrated approach to reducing the impact of coastal floods caused by both SLR and other factors. It also highlighted the importance of coastal community engagement in local DRR activities through increasing risk awareness and adapting to environmental change based on appropriate risk information disclosure by the government. The impacts of coastal floods triggered by SLR and other hazard factors can be reduced by aligning practical regulatory measures with adaptive strategies and enhancing the disaster resilience of coastal communities.展开更多
The accurate identification of marine oil spills and their emulsions is of great significance for emergency response to oil spill pollution.The selection of characteristic bands with strong separability helps to reali...The accurate identification of marine oil spills and their emulsions is of great significance for emergency response to oil spill pollution.The selection of characteristic bands with strong separability helps to realize the rapid calculation of data on aircraft or in orbit,which will improve the timeliness of oil spill emergency monitoring.At the same time,the combination of spectral and spatial features can improve the accuracy of oil spill monitoring.Two ground-based experiments were designed to collect measured airborne hyperspectral data of crude oil and its emulsions,for which the multiscale superpixel level group clustering framework(MSGCF)was used to select spectral feature bands with strong separability.In addition,the double-branch dual-attention(DBDA)model was applied to identify crude oil and its emulsions.Compared with the recognition results based on original hyperspectral images,using the feature bands determined by MSGCF improved the recognition accuracy,and greatly shortened the running time.Moreover,the characteristic bands for quantifying the volume concentration of water-in-oil emulsions were determined,and a quantitative inversion model was constructed and applied to the AVIRIS image of the deepwater horizon oil spill event in 2010.This study verified the effectiveness of feature bands in identifying oil spill pollution types and quantifying concentration,laying foundation for rapid identification and quantification of marine oil spills and their emulsions on aircraft or in orbit.展开更多
Bridging laboratory research and practical utilization is of crucial importance for the development of green ammonia synthetic technologies. A decentralized photo-assisted electrochemical-based demonstrator has been p...Bridging laboratory research and practical utilization is of crucial importance for the development of green ammonia synthetic technologies. A decentralized photo-assisted electrochemical-based demonstrator has been proposed for green ammonia synthesis from renewable electricity, air and water, where well-known defect-laden WO_(3) is used as the working electrode, and a commercially available PV panel supplies renewable electricity. In this demonstrator, defect-laden WO_(3) exhibits the optimum electrochemical NH_(3) formation rate(4.51 × 10^(-12)mol s^(-1)cm^(-2)) in 0.1 M K_(2)SO_(4)in a photovoltaic electrochemical(PV-EC) system. A system-level energy and cost analysis was conducted to investigate its economic viability and a general evaluation tool for system performance and cost estimation was proposed. This advance enables the possibility of integrating the small-scale green ammonia demonstrator into a stand-alone farm system.展开更多
文摘为研究阻尼钢轨的减振降噪性能,以标准钢轨和迷宫式约束阻尼钢轨为研究对象,通过在消声室内测试标准钢轨和迷宫式约束阻尼钢轨的振动与噪声特性,实验结果表明：阻尼钢轨具有良好的减振降噪效果,阻尼钢轨在全频段内有效地抑制振动和噪声。在径向冲击荷载下,迷宫式约束阻尼钢轨相对于标准钢轨的振动加速度衰减量为5%~19%,振动时间衰减量都大于94%,总噪声级降低达9 d B以上;在轴向的冲击荷载下,迷宫式约束阻尼钢轨相对于标准钢轨的振动加速度衰减量为9%~21%,振动时间衰减量都大于92%,总噪声级降低达5 d B以上。实验结果为新型约束阻尼钢轨的优化设计提供了更加准确的实验依据。
基金National Key Research and Development Program of China (2018YFA0707305)Shanxi Provincial Basic Research Program (202203021221149)Major Science and Technology Projects of Shanxi Province (202101120401008)。
文摘Samples of roadside dust were collected from 30 sites in Hong Kong.The total concentrations of 10 metals in the samples were analyzed,and the correlation coefficients among the metal contents and the annual average daily traffic(AADT)in 1986 were determined.Pb was found to have a significant correlation(P<0.01)with AADT.No correlation was found between Al, Ba,Cd,Cr,Cu,Fe,Mn,Ni,and Zn with respect to AADT.A general decrease in the level of Pb in roadside dust in the past few years has been observed since the reduction in the level of lead in petrol.1989 Academic Press,Inc.
基金financial support from the Postgraduate Research & Practice Innovation Program of Jiangsu Province (KYCX24_0690)financial support from the National Natural Science Foundation of China (Project No. 22275088, 52101260)+4 种基金the Project of Shuangchuang Scholar of Jiangsu Province (Project No. JSSCBS20210212)the Fundamental Research Funds for the Central Universities (Project No. 30921011203)the Start-Up Grant (Project No. AE89991/340) from Nanjing University of Science and Technologyfinancial support from the Foundation of Jiangsu Educational Committee (22KJB310008)the Senior Talent Program of Jiangsu University (20JDG073)
文摘Ammonia(NH_(3))is an important raw material for modern agriculture and industry,being widely demanded to sustain the sustainable development of modern society.Currently,the industrial production methods of NH_(3),such as the traditional Haber-Bosch process,have drawbacks including high energy consumption and significant carbon dioxide emissions.In recent years,the electrocatalytic nitrate reduction reaction(NO_(3)RR)powered by intermittent renewable energy sources has gradually become a multidisciplinary research hotspot,as it allows for the efficient synthesis of NH_(3)under mild conditions.In this review,we focus on the research of electrocatalysts with atomic-level site,which have attracted attention due to their extremely high atomic utilization efficiency and unique structural characteristics in the field of NO_(3)RR.Firstly,we introduce the mechanism of nitrate reduction for ammonia synthesis and discuss the in-situ characterization techniques related to the mechanism study.Secondly,we review the progress of the electrocatalysts with atomic-level site for nitrate reduction and explore the structure-activity relationship to guide the rational design of efficient catalysts.Lastly,the conclusions of this review and the challenges and prospective of this promising field are presented.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MIST)(No.2022R1F1A1074289)supported by the Core Research Cluster of Disaster Science in the International Research Institute of Disaster Science(IRIDeS),Tohoku University.
文摘Global warming and climate change significantly increase the frequency of coastal floods caused by sea level rise(SLR) as a permanent factor and hydrometeorological hazards as tentative factors. The combined risks will affect coastal communities.South Korea is gradually facing SLR risks, mainly in its southern coastal regions;however, disaster risk reduction(DRR)in coastal regions remains fragmented. This study aimed to investigate the status of DRR for coastal communities in South Korea by looking at government practices and testimonies from residents. This study reviewed DRR-related regulations and documents and collected data from interviews with local government officials, field visits, and informal conversations with residents in six coastal communities. The findings show that the coastal communities were less resilient to coastal floods than to other hazards, such as typhoons and heavy rains, and the potential consequences could be expanded due to demographic challenges, fragmented institutional systems, and low risk awareness. Moreover, this study emphasized the necessity of an integrated approach to reducing the impact of coastal floods caused by both SLR and other factors. It also highlighted the importance of coastal community engagement in local DRR activities through increasing risk awareness and adapting to environmental change based on appropriate risk information disclosure by the government. The impacts of coastal floods triggered by SLR and other hazard factors can be reduced by aligning practical regulatory measures with adaptive strategies and enhancing the disaster resilience of coastal communities.
基金Supported by the National Natural Science Foundation of China(Nos.42206177,U1906217)the Shandong Provincial Natural Science Foundation(No.ZR2022QD075)the Fundamental Research Funds for the Central Universities(No.21CX06057A)。
文摘The accurate identification of marine oil spills and their emulsions is of great significance for emergency response to oil spill pollution.The selection of characteristic bands with strong separability helps to realize the rapid calculation of data on aircraft or in orbit,which will improve the timeliness of oil spill emergency monitoring.At the same time,the combination of spectral and spatial features can improve the accuracy of oil spill monitoring.Two ground-based experiments were designed to collect measured airborne hyperspectral data of crude oil and its emulsions,for which the multiscale superpixel level group clustering framework(MSGCF)was used to select spectral feature bands with strong separability.In addition,the double-branch dual-attention(DBDA)model was applied to identify crude oil and its emulsions.Compared with the recognition results based on original hyperspectral images,using the feature bands determined by MSGCF improved the recognition accuracy,and greatly shortened the running time.Moreover,the characteristic bands for quantifying the volume concentration of water-in-oil emulsions were determined,and a quantitative inversion model was constructed and applied to the AVIRIS image of the deepwater horizon oil spill event in 2010.This study verified the effectiveness of feature bands in identifying oil spill pollution types and quantifying concentration,laying foundation for rapid identification and quantification of marine oil spills and their emulsions on aircraft or in orbit.
基金grateful to the Natural Sciences and Engineering Council of Canada for supportthe Nation Natural Science Foundation of China (NSFC 21878162,21872102)+4 种基金support of the NSFC(52102311)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams (2019ZT08L101)the Special Fund for the Sci-tech Innovation Strategy of Guangdong Province(210629095860472)the Shenzhen Natural Science Foundation(GXWD20201231105722002-20200824163747001)the Shenzhen Key Laboratory of Eco-materials and Renewable Energy(ZDSYS20200922160400001)。
文摘Bridging laboratory research and practical utilization is of crucial importance for the development of green ammonia synthetic technologies. A decentralized photo-assisted electrochemical-based demonstrator has been proposed for green ammonia synthesis from renewable electricity, air and water, where well-known defect-laden WO_(3) is used as the working electrode, and a commercially available PV panel supplies renewable electricity. In this demonstrator, defect-laden WO_(3) exhibits the optimum electrochemical NH_(3) formation rate(4.51 × 10^(-12)mol s^(-1)cm^(-2)) in 0.1 M K_(2)SO_(4)in a photovoltaic electrochemical(PV-EC) system. A system-level energy and cost analysis was conducted to investigate its economic viability and a general evaluation tool for system performance and cost estimation was proposed. This advance enables the possibility of integrating the small-scale green ammonia demonstrator into a stand-alone farm system.
