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Biogenic volatile organic compound emission patterns and secondary pollutant formation potentials of dominant greening trees in Chengdu,southwest China

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Journal of Environmental Sciences 2022年第4期34卷 179-193页

作者： liping liu Barnabas C.Seyler Hefan liu li Zhou Dongyang Chen Song liu Chang Yan Fumo Yang Danlin Song Qinwen Tan Fengju Jia Cheng Feng Qiuwei Wang yunchun li College of Architecture and Environment Sichuan UniversityChengdu 610065China College of Science Sichuan Agricultural UniversityYa’an 625014China Chengdu Academy of Environmental Sciences Chengdu 610000China Chengdu Ecological and Environmental Monitoring Center Chengdu 610000China Longquanyi Ecology and Environment Bureau Chengdu 610000China

Integral to the urban ecosystem,greening trees provide many ecological benefits,but the active biogenic volatile organic compounds(BVOCs)they release contribute to the production of ozone and secondary organic aerosols,which harm ambient air quality.It is,therefore,necessary to understand the BVOC emission characteristics of dominant greening tree species and their relative contribution to secondary pollutants in various urban contexts.Consequently,this study utilized a dynamic enclosure system to collect BVOC samples of seven dominant greening tree species in urban Chengdu,Southwest China.Gas chromatography/mass spectrometry was used to analyze the BVOC components and standardized BVOC emission rates of each tree species were then calculated to assess their relative potential to form secondary pollutants.We found obvious differences in the composition of BVOCs emitted by each species.Ficus virens displayed a high isoprene emission rate at31.472μgC/(gdw(g dry weight)·hr),while Cinnamomum camphora emitted high volumes of D-limonene at 93.574μgC/(gdw·hr).In terms of the BVOC emission rates by leaf area,C.camphora had the highest emission rate of total BVOCs at 13,782.59μgC/(m^(2)·hr),followed by Cedrus deodara with 5466.86μgC/(m^(2)·hr).Ginkgo biloba and Osmanthus fragrans mainly emitted oxygenated VOCs with lower overall emission rates.The high BVOC emitters like F.virens,C.camphora,and Magnolia grandiflora have high potential for significantly contributing to environmental secondary pollutants,so should be cautiously considered for future planting.This study provides important implications for improving urban greening efforts for subtropical Chinese urban contexts,like Chengdu.

关键词： Biogenic volatile organic compounds(BVOCs) Dynamic enclosure system Emission characteristics Secondary pollutants

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数字金融与区域创新差距

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统计与信息论坛 2024年第7期39卷 69-81页

作者：王尹君曹允春李彦龙郑州大学商学院河南郑州450000 河南牧业经济学院经济与贸易学院河南郑州450000 中国社会科学院大学经济学院北京102488 北京大学数字金融研究中心北京100871

数字金融作用于区域创新发展路径,对推动区域创新均衡协调发展具有重要意义。结合北京大学数字普惠金融指数、省市级宏观数据和上市公司等多维度数据,基于泰尔指数、基尼系数和阿特金森指数测度了区域创新发展差异,多方位考察数字金融... 详细信息

数字金融作用于区域创新发展路径,对推动区域创新均衡协调发展具有重要意义。结合北京大学数字普惠金融指数、省市级宏观数据和上市公司等多维度数据,基于泰尔指数、基尼系数和阿特金森指数测度了区域创新发展差异,多方位考察数字金融指数及数字覆盖范围、使用程度、支持服务力度与区域创新差距之间的关系,并探索数字金融影响区域创新差距的传导机制和微观基础。研究发现,数字金融的发展有利于缩小省内各地级市间的创新差距,并且数字金融的普惠效应在东部地区和省份内部创新差异较小的地区更强。进一步的传导机制分析表明,数字金融能够促进传统金融与信息基础设施的有效结合,提高信息基础设施对区域创新差距的边际影响。但值得注意的是,数字金融并不能显著推动省份之间创新的均衡化发展。微观分析结果表明,数字金融能够缩小企业间创新差距,但是不利于东部和中西部地区之间创新的均衡化发展。因此要进一步深化数字金融发展,实施差异化的发展策略,为区域创新的平衡发展提供强劲动力。研究结论不仅能够为推动区域技术创新、缩小地区创新差距提供理论基础,还可以为区域协调发展提供一定的启示。

关键词：数字金融创新差距异质性传导机制微观基础

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基于复杂网络的中国与东盟航空运输联系研究

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物流科技 2024年第1期47卷 118-121页

作者：曹允春李嘉玉中国民航大学临空经济研究中心天津300300 中国民航大学交通科学与工程学院天津300300

为探究我国同东盟航空运输联系发展水平,采用修正的引力模型对联系强度进行测算,基于测算结果构建中国与东盟城市航空运输联系空间网络,运用复杂网络方法对网络总体特征和节点中心性进行分析,发现我国与东盟航空联系强度较弱,整体呈上... 详细信息

为探究我国同东盟航空运输联系发展水平,采用修正的引力模型对联系强度进行测算,基于测算结果构建中国与东盟城市航空运输联系空间网络,运用复杂网络方法对网络总体特征和节点中心性进行分析,发现我国与东盟航空联系强度较弱,整体呈上升趋势,联系的不均衡性较为明显;整体网络结构较为松散,呈现出“核心—边缘”的分布特点;度分布表现出多级分化现象,网络由少数核心城市主导,接近中心性总体分布均衡。

关键词：复杂网络航空运输联系修正的引力模型中国—东盟

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SDN-Based Switch Implementation on Network Processors

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Communications and Network 2013年第3期5卷 434-437页

作者： yunchun li Guodong Wang School of Computer Science and Engineering BeiHang University Beijing China

Virtualization is the key technology of cloud computing. Network virtualization plays an important role in this field. Its performance is very relevant to network virtualizing. Nowadays its implementations are mainly based on the idea of Software Define Network (SDN). Open vSwitch is a sort of software virtual switch, which conforms to the OpenFlow protocol standard. It is basically deployed in the linux kernel hypervisor. This leads to its performance relatively poor because of the limited system resource. In turn, the packet process throughput is very low.In this paper, we present a Cavium-based Open vSwitch implementation. The Cavium platform features with multi cores and couples of hard ac-celerators. It supports zero-copy of packets and handles packet more quickly. We also carry some experiments on the platform. It indicates that we can use it in the enterprise network or campus network as convergence layer and core layer device.

关键词： SDN Open vSwitch Network Processors OpenFlow

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Low concentration isopropanol gas sensing properties of Ag nanoparticles decorated In_(2)O_(3) hollow spheres

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Journal of Advanced Ceramics 2022年第3期11卷 379-391页

作者： Chao ZHANG yunchun HUAN Ying li Yifan LUO Marc DEBliQUY College of Mechanical Engineering Yangzhou UniversityYangzhou225127China Materials Science Department University of MonsMons7000Belgium

In order to detect low concentrations of volatile organic compounds (VOCs) for the early diagnosis of lung cancer, sensors based on hollow spheres of In_(2)O_(3) were prepared through the soft template method. Ag nanoparticle decorated In_(2)O_(3) composites were synthesized via dipping and annealing. The microstructure, phase composition, element distribution, and state of Ag were analyzed by the scanning electron microscopy (SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). The gas sensing tests showed that Ag-In_(2)O_(3) sensors had the highest response to isopropanol at 300 ℃. The best response of Ag-In_(2)O_(3) composite sensor was 5.2, which had a significant improvement compared with only In_(2)O_(3). Moreover, the response and recovery time of Ag-In_(2)O_(3) composite sensor was significantly shortened. The improved sensing properties of Ag-In_(2)O_(3) composite sensor could be attributed to the Schottky barrier created at Ag-In_(2)O_(3) interface and catalytical effect of Ag.

关键词： Ag-In_(2)O_(3) hollow spheres isopropanol gas sensor

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Adaptive watermark generation mechanism based on time series prediction for stream processing

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Frontiers of Computer Science 2021年第6期15卷 59-73页

作者： Yang SONG yunchun li Hailong YANG Jun XU Zerong LUAN Wei li Sino-German Joint Software Institute Beihang UniversityBeijing 100191China School of Computer Science and Engineering Beihang UniversityBeijing 100191China Science and Technology on Space System Simulation Laboratory Beijing Simulation Center Beijing 100854China College of life Sciences and Bioengineering Beijing University of TechnologyBeijing 100083China

The data stream processing framework processes the stream data based on event-time to ensure that the request can be responded to in real-time.In reality,streaming data usually arrives out-of-order due to factors such as network delay.The data stream processing framework commonly adopts the watermark mechanism to address the data disorderedness.Watermark is a special kind of data inserted into the data stream with a timestamp,which helps the framework to decide whether the data received is late and thus be discarded.Traditional watermark generation strategies are periodic;they cannot dynamically adjust the watermark distribution to balance the responsiveness and accuracy.This paper proposes an adaptive watermark generation mechanism based on the time series prediction model to address the above limitation.This mechanism dynamically adjusts the frequency and timing of watermark distribution using the disordered data ratio and other lateness properties of the data stream to improve the system responsiveness while ensuring acceptable result accuracy.We implement the proposed mechanism on top of Flink and evaluate it with realworld datasets.The experiment results show that our mechanism is superior to the existing watermark distribution strategies in terms of both system responsiveness and result accuracy.

关键词： data stream processing watermark time series based prediction dynamic adjustment

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一种动车组五级修车辆分解作业平台工艺设计

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机械管理开发 2024年第5期39卷 124-126页

作者：刘文莲桑运春李传戈高建辉青岛城市学院山东青岛266000 青岛四方阿尔斯通铁路运输设备有限公司山东青岛266000

近年来高速动车组在我国得到飞速发展,为有效提高动车组检修效率,压缩检修周期,提高动车组的上线率,增加动车组的运营经济效益,建立规范、高效的检修平台是动车组检修的必然趋势。规范高效的检修平台采用三层立体检修作业平台设计方案,... 详细信息

近年来高速动车组在我国得到飞速发展,为有效提高动车组检修效率,压缩检修周期,提高动车组的上线率,增加动车组的运营经济效益,建立规范、高效的检修平台是动车组检修的必然趋势。规范高效的检修平台采用三层立体检修作业平台设计方案,实现车顶、车内和车下同步检修作业,减轻了劳动强度,提高了检修生产效率,保障了车顶检修作业的安全。

关键词：动车组五级修车辆分解作业平台

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长余辉材料在发光路面上的应用及研究进展

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上海师范大学学报（自然科学版中英文） 2024年第1期53卷 89-96页

作者：吴春杰廖庆良张庆萧徐韵淳张宸豪李辉上海师范大学化学与材料科学学院上海200234 上海浦东路桥(集团)有限公司工程技术研究所上海201206

文章首先介绍了长余辉材料的发光机理,探讨了它的主要应用,并分析了目前存在的一些问题.然后,提出了一些有关长余辉材料的发展建议,以期为相关领域的研究人员提供一些指引和帮助.最后,总结了长余辉材料的发展趋势,并对未来的发展前景进... 详细信息

文章首先介绍了长余辉材料的发光机理,探讨了它的主要应用,并分析了目前存在的一些问题.然后,提出了一些有关长余辉材料的发展建议,以期为相关领域的研究人员提供一些指引和帮助.最后,总结了长余辉材料的发展趋势,并对未来的发展前景进行了展望.

关键词：长余辉材料发光机理发光路面

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Dominant Marker-based Identification of Reproductive Modes in Hickory (Carya cathayensis Sarg.)

Dominant Marker-based Identification of Reproductive Modes i...

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生态文明建设中的植物学：现在与未来——中国植物学会第十...

作者： Yanru Zeng Wei Hou yunchun li Rongling Wu The Nurturing Station for the State Key Laboratory of Subtropical Silviculture Zhejiang A & F University Center for Statistical Genetics Pennsylvania State University

Hickory, an important non-timber species in Zhejiang Province, has unisexual and monoecious flowers. So far there has been no cultivar under the species. In recent years it has been found that hickory is an apomictic plant. Based on a fact of open pollination and random mating in a natural population, a data set of molecular markers and a likelihood function were established, in which outcross, apomixis and selfing are considered, respectively and EM algorithm is used to estimate unknown parameters including rates of outcross (ω), apomixis (θ) and selfing (1-θ-ω). Significance of both outcross and apomixis is tested and computer simulation is performed to test the accuracy of the parameters estimated by the statistical model in terms of two sample sizes (200 and 400). It is shown that the model developed can well estimate all the parameters, and it would be better when the sample size is increased. With the model established and a dominant marker data (RAPD and SRAP) set from a population that consists of 40 parent trees from a natural population and their 10 progeny seedlings each (totally 440 samples), we estimated that rates of outcross (ω), apomixis (θ) and selfing (1-θ-ω) in hickory were 66.27%, 32.36% and 1.37%, respectively.

关键词： hickory （Carya cathayensis Sarg.） apomixis reproductive mode molecular marker

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Effect of aging on the mechanical properties and corrosion susceptibility of an Al-Cu-li-Zr alloy containing Sc

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Rare Metals 2008年第2期27卷 146-152页

作者： liANG Wenjie PAN Qinglin HE Yunbin li yunchun ZHOU Yingchun LU Congge School of Materials Science and Engineering Central South University Changsha 410083 China

Al-3.5Cu-1.5li-0.22 (Sc+Zr ) 合金的微观结构，机械性质， intergranular 腐蚀，和脱落腐蚀上的老化的效果被调查了。结果证明合金有年龄变硬，和降水的主要阶段的特性，加强是 T1 阶段。变老的温度和老化时间在 T1 阶段的数量和分发... 详细信息

Al-3.5Cu-1.5li-0.22 (Sc+Zr ) 合金的微观结构，机械性质， intergranular 腐蚀，和脱落腐蚀上的老化的效果被调查了。结果证明合金有年龄变硬，和降水的主要阶段的特性，加强是 T1 阶段。变老的温度和老化时间在 T1 阶段的数量和分发上有重要效果。合金的合适的人工的单个老化的处理在 160r_

关键词： Al-li合金老化现象微结构腐蚀现象

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