检索结果-南通市图书馆

Factors contributing to the oxygen concentration over the Qinghai-Tibetan Plateau and its contribution rate calculation

引用

Science China Earth Sciences 2024年第2期67卷 497-509页

作者： Peijun SHI Ying ZHANG yanqiang chen Wenquan ZHU Xiaokang HU Heyi YANG Lu JIANG Yonggui MA Haiping TANG State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing100875China Key Laboratory of Environmental Change and Natural Disaster Ministry of EducationBeijing Normal UniversityBeijing100875China The Institute for Disaster Management and Reconstruction Sichuan UniversityChengdu610065China Academy of Plateau Science and Sustainability People’s Government of Qinghai Province&Beijing Normal UniversityXining810016China

A decline in atmospheric oxygen concentration is projected in the 21st century given the background of global warming.The Qinghai-Tibetan Plateau is located at a high altitude,and thus,it faces a hypoxia challenge;however,knowledge of the factors contributing to its atmospheric oxygen concentration is still lacking.Here,we conducted joint observations of ecosystem oxygen production and carbon sinks and near-surface atmospheric oxygen concentrations on the Qinghai-Tibetan Plateau and meteorological elements at Beijing Fangshan Station.Using seasonal differences and statistical methods,we calculated the relative contribution rates of vegetation to changes in atmospheric oxygen concentration.Our results indicate that solar radiation,atmospheric humidity,and ecosystem oxygen consumption and production have a significant impact on the atmospheric oxygen concentration,and the impact shows temporal and spatial differences.Vegetation significantly impacts the oxygen concentration,with a contribution rate of 16.7%–24.5%,which is underestimated in existing research.Our findings provide important insights into the factors that influence atmospheric oxygen concentration and highlight the contribution of vegetation.To better understand the oxygen dynamics of the Qinghai-Tibetan Plateau,we recommend further field observations of soil respiration and vegetation photosynthesis to clarify the contributions of carbon storage,carbon sinks and other factors to the near-surface atmospheric oxygen concentration.

关键词： Qinghai-Tibetan Plateau Oxygen concentration Relative contribution rate Air temperature Vegetation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Empowering smart city situational awareness via big mobile data

引用

Frontiers of Information Technology & Electronic Engineering 2024年第2期25卷 286-307页

作者： Zhiguang SHAN Lei SHI Bo LI yanqiang ZHANG Xiatian ZHANG Wei chen State Information Center Beijing100045China School of Computer Science and Engineering Beihang UniversityBeijing100191China Zhongguancun Laboratory Beijing100094China Beijing Tendcloud Tianxia Technology Co. Ltd.Beijing100027China The State Key Lab of CAD&CG Zhejiang UniversityHangzhou310027China

Smart city situational awareness has recently emerged as a hot topic in research societies,industries,and governments because of its potential to integrate cutting-edge information technology and solve urgent challenges that modern cities face.For example,in the latest five-year plan,the Chinese government has highlighted the demand to empower smart city management with new technologies such as big data and Internet of Things,for which situational awareness is normally the crucial first step.While traditional static surveillance data on cities have been available for decades,this review reports a type of relatively new yet highly important urban data source,i.e.,the big mobile data collected by devices with various levels of mobility representing the movement and distribution of public and private agents in the city.We especially focus on smart city situational awareness enabled by synthesizing the localization of hundreds of thousands of mobile software Apps using the Global Positioning System(GPS).This technique enjoys advantages such as a large penetration rate(∼50%urban population covered),uniform spatiotemporal coverage,and high localization precision.We first discuss the pragmatic requirements for smart city situational awareness and the challenges faced.Then we introduce two suites of empowering technologies that help fulfill the requirements of(1)cybersecurity insurance for smart cities and(2)spatiotemporal modeling and visualization for situational awareness,both via big mobile data.The main contributions of this review lie in the description of a comprehensive technological framework for smart city situational awareness and the demonstration of its feasibility via real-world applications.

关键词： Smart city Mobile data Situational awareness

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Thermo-Flow Performances for the Main-Auxiliary Integrated Natural Draft Dry Cooling System

引用

Journal of Thermal Science 2024年第3期33卷 1010-1025页

作者： ZHANG Zongyang HOU Yichen ZHOU Hanyu JIA He chen Lei KONG yanqiang WANG Weijia YANG Lijun DU Xiaoze Key Laboratory of Power Station Energy Transfer Conversion and System of Ministry of Education School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China

Recently,natural draft dry cooling system with the main-auxiliary integrated air-cooled heat exchangers in the up and lower layers,has drawn attention to the electric power industry.This research firstly develops two physical models for the integrated cooling system,namely Case A and Case B.In Case A,the main air-cooled heat exchanger is arranged in the upper layer and the auxiliary air-cooled heat exchanger arranged in the lower layer,while in Case B,the two heat exchanger systems are arranged in the opposite way.And then,directing at the engineering TMCR and TRL 1 working conditions,the unit-local-overall thermo-flow characteristics of Case A and Case B are obtained and compared by numerical simulation.The findings show that,for the auxiliary air-cooled exchanger,Case A has obviously higher cooling performances than Case B,with the difference varying from 5.46%to 7.55%.Whereas,for the main air-cooled exchanger,Case B shows the recovered cooling performances,with the difference changing from 1.15%to 2.99%.Case A is preferably recommended to the engineering application in consideration of more strict cooling demand of the auxiliary cooling system.Conclusively,this research will provide some theoretical guidelines for the design and construction of the main-auxiliary integrated natural draft dry cooling system.

关键词： integrated dry cooling system main air-cooled heat exchanger auxiliary air-cooled heat exchanger upper layer and lower layer thermo-flow performances

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Carbon Emission Risk and Governance

引用

International Journal of Disaster Risk Science 2022年第2期13卷 249-260页

作者： Lu Jiang Xiaokang Hu Gangfeng Zhang yanqiang chen Honglin Zhong Peijun Shi Academy of Plateau Science and Sustainability People’s Government of Qinghai Province and Beijing Normal UniversityXining 810016China State Key Laboratory of Surface Processes and Resource Ecology Beijing Normal UniversityBeijing 100875China Academy of Disaster Reduction and Emergency Management Ministry of Emergency Management and Ministry of EducationBeijing Normal UniversityBeijing 100875China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China Institute of Blue and Green Development Weihai Institute of Interdisciplinary ResearchShandong UniversityWeihai 264209China

Within the hazard and disaster risk research field, explicitly treating carbon emissions as a hazard remains rather nascent. Applying hazard and disaster risk research perspectives to seek new insights on integrated mitigation and adaptation approaches and policy measures is equally elusive. Since China’s pledge to achieve carbon neutrality by 2060, the ‘‘dual carbon” goals of carbon emission peaking and neutrality have stimulated nationwide attention, research, and policies and action plans.How to ensure that the transition pathways are on track and well-contextualized is one of the crucial challenges for policymakers and practitioners. This article examines the‘‘risks” of missing the carbon neutrality goal at a regional scale in China, denoted as Carbon Emission Risk(CER).Carbon emissions(CE) as hazard, combined with the human socioeconomic system as exposure and human living environment, constitute the regional carbon emission environmental risk system. The ‘‘risks” of missing(or achieving) the carbon neutrality target for any region at any time, the article argues, is essentially determined by the ratio of CE to carbon absorption(CA, for uptake and removal). These variables are modified by a broadly defined ‘‘vulnerability coefficient”(Cv) that embodies both the potential for changes(decreasing CE and increasing CA), and the uncertainties of measuring CE and CA. Thus,the ratio of CE to CA is a measure of reality at any moment of time, whereas Cv indicates the overall propensity or capacity for moving the CE/CA ratio towards 1, that is,realizing carbon neutrality. Based on our calculation, CER at the provincial level in eastern China is higher than in western China. The article also calls for strengthening CER research and summarizes key measures for carbon emission risk governance.

关键词： Carbon emission risks Carbon neutrality Low-carbon economy Risk governance Vulnerability coefficient

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

水泥基材料中Ca^(2+)对矿化微生物的碳酸酐酶产量、活性和矿化的影响

引用

材料导报 2024年第8期38卷 131-136页

作者：张俊杰陈燕强钱春香东南大学材料科学与工程学院南京211189 东南大学绿色建材与固碳研究中心南京211189 中国建筑行业微生物矿化技术重点实验室南京211189 东南大学江苏省土木工程材料重点实验室南京211189

本工作针对一种适用于水泥基材料的耐碱矿化微生物,研究了水泥基材料中Ca^(2+)浓度变化(0~5 mmol/L)对矿化微生物的产酶量、碳酸酐酶活性以及诱导CaCO_(3)矿化能力的影响。对分离纯化不同Ca^(2+)浓度菌液中的碳酸酐酶进行酶产量测定,并... 详细信息

本工作针对一种适用于水泥基材料的耐碱矿化微生物,研究了水泥基材料中Ca^(2+)浓度变化(0~5 mmol/L)对矿化微生物的产酶量、碳酸酐酶活性以及诱导CaCO_(3)矿化能力的影响。对分离纯化不同Ca^(2+)浓度菌液中的碳酸酐酶进行酶产量测定,并通过测定矿化微生物的细菌生长曲线和单菌产酶量分析Ca^(2+)浓度对其的影响机理;基于酯酶法测定不同Ca^(2+)浓度下碳酸酐酶的活性,并利用FTIR测定官能团,分析二级结构变化和氢键变化,进而得到Ca^(2+)浓度对碳酸酐酶活性的影响机理;最后基于热重分析不同Ca^(2+)浓度溶液中矿化微生物的诱导矿化能力,并测定矿化产物晶形。试验结果表明,当Ca^(2+)浓度为2.5 mmol/L时,矿化微生物生长增殖最快,单菌产酶量最高,因此整体酶产量最高;碳酸酐酶活性在Ca^(2+)浓度为5 mmol/L时达到最大值,但Ca^(2+)会破坏碳酸酐酶结构的有序性;当Ca^(2+)浓度为5 mmol/L时,矿化微生物的诱导矿化能力最强,矿化3 d后Ca(OH)_(2)向CaCO_(3)的转化率达到82.67%,且得到的CaCO_(3)晶体形貌主要为球状或椭圆状。

关键词：矿化微生物碳酸酐酶酶产量酶活性诱导矿化

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Atomically Dispersed Ruthenium Catalysts with Open Hollow Structure for Lithium-Oxygen Batteries

引用

Nano-Micro Letters 2024年第2期16卷 154-164页

作者： Xin chen Yu Zhang Chang chen Huinan Li Yuran Lin Ke Yu Caiyun Nan chen chen Beijing Advanced Innovation Center for Materials Genome Engineering Institute of Solid State ChemistryUniversity of Science and Technology BeijingBeijing 100083People’s Republic of China Engineering Research Center of Advanced Rare Earth Materials Department of ChemistryTsinghua UniversityBeijing 100084People’s Republic of China Beijing Key Laboratory of Energy Conversion and Storage Materials Institution College of ChemistryBeijing Normal UniversityBeijing 100875People’s Republic of China

Lithium–oxygen battery with ultrahigh theoretical energy density is considered a highly competitive next-generation energy storage device,but its practical application is severely hindered by issues such as difficult decomposition of discharge products at present.Here,we have developed N-doped carbon anchored atomically dispersed Ru sites cathode catalyst with open hollow structure(h-RuNC)for Lithium–oxygen battery.On one hand,the abundance of atomically dispersed Ru sites can effectively catalyze the formation and decomposition of discharge products,thereby greatly enhancing the redox kinetics.On the other hand,the open hollow structure not only enhances the mass activity of atomically dispersed Ru sites but also improves the diffusion efficiency of catalytic molecules.Therefore,the excellent activity from atomically dispersed Ru sites and the enhanced diffusion from open hollow structure respectively improve the redox kinetics and cycling stability,ultimately achieving a high-performance lithium–oxygen battery.

关键词： Atomically dispersed Open hollow structure Discharge product Lithium Oxygen battery

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Advances in the application of hydrogel-based scaffolds for tendon repair

引用

Genes & Diseases 2024年第4期11卷 296-313页

作者： Renqiang chen Fanglin chen Kenian chen Jian Xu Department of Orthopedics The First Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang 310003China Department of Orthopedics The Fourth Affiliated Hospital of Guangxi Medical UniversityLiuzhou Guangxi 545005China

Tendon injuries often lead to joint dysfunction due to the limited self-regeneration capacity of tendons.Repairing tendons is a major challenge for surgeons and imposes a signif-icant financial burden on society.Therefore,there is an urgent need to develop effective stra-tegies for repairing injured tendons.Tendon tissue engineering using hydrogels has emerged as a promising approach that has attracted considerable interest.Hydrogels possess excellent biocompatibility and biodegradability,enabling them to create an extracellular matrix-like growth environment for cells.They can also serve as a carrier for cells or other substances to accelerate tendon repair.In the past decade,numerous studies have made significant prog-ress in the preparation of hydrogel scaffolds for tendon healing.This review aims to provide an overview of recent research on the materials of hydrogel-based scaffolds used for tendon tis-sue engineering and discusses the delivery systems based on them.

关键词： Application Hydrogel-based Repairscaffolds Review Tendon injury Tissue engineering

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Photodegradation of xylene isomers:Kinetics,mechanism,secondary pollutant formation potential and health risk evaluation

引用

Journal of Environmental Sciences 2024年第2期136卷 658-669页

作者： Xiaoyan chen Weikun Zhu Sufen Feng Jiangyao chen Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control Guangdong Technology Research Center for Photocatalytic Technology Integration and Equipment EngineeringInstitute of Environmental Health and Pollution ControlGuangdong University of TechnologyGuangzhou 510006China Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and HealthSchool of Environmental Science and EngineeringGuangdong University of TechnologyGuangzhou 510006China

Photodegradation technology has been widely applied in the purification of industrial aromatic hydrocarbons.However,whether this technology efficiently removes the pollutants to prevent secondary pollution and health risk is still unclear.Here,the photodegradation processes of three xylenes were compared under designed reaction atmospheres and light sources.Xe lamp showed poor photodegradation ability toward xylenes,no matter in N_(2) or N_(2)+O_(2)system,while much higher photodegradation performance of xylenes were obtained under ultraviolet(UV)and vacuum ultraviolet(VUV)irradiation,especially in N_(2)+O_(2)+VUV system,where 97.9%of m-xylene,99.0%of o-xylene or 87.5%of p-xylene with the initial concentration of 860 mg/m^(3) was removed within 240 min.The xylenes underwent three processes of photo-isomerization,photodecomposition and photo-oxidation to produce intermediates of aromatics,alkanes and carbonyls.Among them,the photo-isomerization products showed the highest concentration percentage(e.g.,≥50%in o-xylene system),confirming that photo-isomerization reaction was the dominated photodegradation process of xylenes.Moreover,these isomerized products not only contributed about 97%and91%to the formation potential of O3(OFP)and secondary organic aerosols(SOAFP),but also displayed obvious non-carcinogenic risk,although one of photodecomposition product—benzene showed the highest occupational exposure risk.Therefore,the secondary pollution and health risks of photodegradation products of xylenes were non-ignorable,although the OFP,SOAFP and health risks of the generated products reduced at least 4.5 times in comparison with that of the degraded xylenes.The findings are helpful for the appropriate application of this technology in the purification of industrial organic waste gas.

关键词： Isomer aromatics Photodegradation Ozone formation Secondary organic aerosols Health risk

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Isotopic characteristics and source analysis of atmospheric ammonia during agricultural periods in the Xichuan area of the Danjiangkou Reservoir

引用

Journal of Environmental Sciences 2024年第2期136卷 460-469页

作者： Xiaoshu chen Tongqian Zhao Chunyan Xiao Xiaoming Guo Feihong chen Institute of Resources and Environment Henan Polytechnic UniversityJiaozuo 454000China

Nitrogen deposition is an important means of exogenous nitrogen input in reservoir water.Agricultural activities around the reservoir lead to a sharp increase in the concentration of ammonia in the atmosphere,which poses a threat to the reservoir water body.Clarifying the contribution of agricultural ammonia release to atmospheric NH_(x)(gaseous NH_(3)and particulate NH_(4)^(+)),in the reservoir area can provide a theoretical foundation for local reactive nitrogen control.We collected atmospheric NH_(3)and NH_(4)^(+)samples during the agricultural periods and analyzed the isotopic characteristics of atmospheric NH_(x)and the contribution rates of different ammonia sources in the Xichuan area of the Danjiangkou Reservoir.The results showed that the initialδ~(15)N values of NH_(3)(-30.0‰to–7.2‰)and particulate NH_(4)^(+)(–33‰to+4.9‰for finer and coarser particles,respectively)are different,and their contribution ratios from dissimilar ammonia sources are also different,among which NH_(4)^(+)is more susceptible to meteorological factors.However,since the atmospheric NH_(x)in the Xichuan area is mainly gaseous NH_(3),the final sources of atmospheric ammonia nitrogen source depend on gaseous NH_(3).Agricultural sources(59%-74%)were the main NH_(3)sources in this area.Among them,the fertilizer use emission was dominant;it had the highest contribution rate in summer during the agricultural period and a more prominent impact in areas with less human interference.Reasonable regulation of the application of high-ammonia releasing fertilizer,especially during the agricultural period in summer,is an effective way to reduce the threat of atmospheric ammonia to water health.

关键词： Danjiangkou reservoir Atmospheric ammonia nitrogen Isotope Ammonia source analysis Agricultural sources

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Meridional deflection of global eddy propagation derived from tandem altimetry: Mechanism and implication

引用

Science China Earth Sciences 2024年第3期67卷 811-825页

作者： Ge chen Xiaoyan chen Frontiers Science Center for Deep Ocean Multispheres and Earth System School of Marine TechnologyOcean University of ChinaQindao 266100China Laboratory for Regional Oceanography and Numerical Modeling Laoshan LaboratoryQindao 266237China

A common view on meridional deflection of eddy propagation is poleward for cyclones and equatorward for anticyclones. This widely accepted polarity-sensitive pattern has been increasingly undermined given that it is systematically violated on both zonal and regional scales as recently reported. Here, we approach the problem by exploring these violations in terms of eddy effects of spatiotemporal geostrophy, thermal fading, and flow dragging, yielding the following main conclusions.(1) The polarity-dependent deflection discrepancy is a pseudo feature resulting from a biased fit to the normalized eddy tracks which are spatially asymmetric(though azimuthally symmetric) between the two signs;Instead, the primary pattern of eddy deflection appears to be geographically correlated and polarity independent.(2) Geostrophic adjustment plays a critical role in defining the meridional movement of an eddy. Specifically, a consistent poleward(equatorward) trajectory bending of spatially(temporally) ageostrophic eddies is observed irrespective of their polarity.(3) The mechanism of eddy deflection is also determined by its zonal propagation direction. Westward propagating eddies are substantially affected by thermal fading, while opposite ones by flow dragging. A realistic and comprehensive understanding of eddy deflection mechanisms serves as a significant contribution to the prediction of eddy trajectory, and the protection of ocean environment.

关键词： Mesoscale eddies Eddy propagation Eddy meridional deflection Satellite observation Geostrophic adjustment

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：