检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

城市水系统理论及其模型研制与应用

中国科学：地球科学 2024年第3期54卷 725-744页

作者：夏军张永勇佘敦先张世彦杨军吕明权张翔罗安琪吴胜军刘阳中国科学院地理科学与资源研究所陆地水循环及地表过程重点实验室北京100101 武汉大学水资源与水电工程科学国家重点实验室武汉430072 中国科学院城市环境研究所城市环境与健康重点实验室福建省流域生态重点实验室水生态健康研究组厦门361021 中国科学院重庆绿色智能技术研究院重庆400714

城市水系统理论是流域水系统科学在城市尺度的拓展,为解决城市化引起的人水关系失衡和突出水问题(内涝、黑臭和水污染、生态退化等)提供了新的系统化解决方案.现有城市水系统相关研究大多关注水循环单一过程,对水循环及其伴生的物质循... 详细信息

城市水系统理论是流域水系统科学在城市尺度的拓展,为解决城市化引起的人水关系失衡和突出水问题(内涝、黑臭和水污染、生态退化等)提供了新的系统化解决方案.现有城市水系统相关研究大多关注水循环单一过程,对水循环及其伴生的物质循环、水生态以及人文等过程互馈机制仍需进一步探索.本文以流域水系统科学和水循环理论为基础,发展了城市水系统的概念、理论和技术体系;以城市多种下垫面条件下时变增益降雨-径流模型为核心,耦合自然-社会水循环及其伴生的水环境、水生态等过程和多尺度海绵措施的影响,研发了城市水系统5.0模型,实现了源头降雨-径流-面源污染负荷、排水管网系统水量水质转输、末端调蓄和净化、社会经济水循环、水系统评估和调控等五大关键模拟功能,成果已在武汉市开展示范应用.结果表明:城市水系统应以城市及其联系的河湖为研究对象,探索城市自然-人工侧支水循环和外江调蓄等耦合,以及社会经济发展、海绵措施对水量-水质-水生态等过程的调控机制.研发的城市水系统5.0模型很好地模拟了城区降雨-径流过程、水体总氮和总磷浓度、社会经济发展特征指标等.与实测数据对比,所有降雨-径流场次的相关系数和纳什效率系数分别处于优秀和良好等级;78.1%的实测点位中总氮和总磷浓度模拟偏差均在良好等级,且相关系数均在0.90以上;在18个社会经济发展特征指标中, 100%、83.3%和69.4%的指标偏差、相关系数和纳什效率系数均在优秀等级.在此基础上,优选源头海绵措施、人工强化措施和源头削减-路径拦截-末端治理等分别明显改善了内涝、水体黑臭和湖泊富营养化.其中10年一遇降雨条件下最大内涝淹没面积削减达32.6%,黑臭水体去除率为65%,水体综合营养指数降低了37%,武汉市2020年绿色发展水平也由现状条件下的0.56提升到了0.67,在城市绿色发展评估体系的五个维度(资源利用、环境质量、生态保护、经济增长和绿色生活)中,生态保护维度改善最明显.本研究将进一步推动城市水文学、环境科学和生态学等多学科领域的交叉和发展,也为我国城市复杂水问题的解决和绿色发展等提供重要的理论和技术基础.

关键词：城市水系统人水关系水问题绿色发展理论基础数学模型

A NEW METHOD FOR MEASURING LONG-TERMCREEP DEFORMATION IN A SMALL REGION

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1998年第6期11卷 442-448页

作者： j.M.Gong S.T.Tu j.xia X.Ling Nanjing Univ of Chemical Technology Nanjing China

Creep deformation localization is generally found in structures at high temperamture,typically in weldments. As the heat affected zone (HAZ) in a weldment is very narrow, deformation in HAZ region can hardly be measured by conventional displacement gauge. A new method for measuring long-term local creep deformation was developed by quartz optical fiber and technique of digital image analysis. The creep deformations of base metal, weld metal and HAZ in weldments are thereby determined with crossweld specimens.

关键词： creep deformation weldment quartz optical fiber image analysis

Homogenization of climate series:The basis for assessing climate changes

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2014年第10期57卷 2891-2900页

作者： YAN ZhongWei LI Zhen xia jiangjiang Key Laboratory of Regional Climate-Environment for East Asia (RCE-TEA) Institute of Atmospheric Physics Chinese Academy of Sciences

Long-term meteorological observation series are fundamental for reflecting climate ***,almost all meteorological stations inevitably undergo relocation or changes in observation instruments,rules,and methods,which can result in systematic biases in the observation series for corresponding *** is a technique for adjusting these biases in order to assess the true trends in the time *** recent years,homogenization has shifted its focus from the adjustments to climate mean status to the adjustments to information about climate extremes or extreme *** case analyses of ideal and actual climate series,here we demonstrate the basic idea of homogenization,introduce new understanding obtained from recent studies of homogenization of climate series in China,and raise issues for further studies in this field,especially with regards to climate extremes,uncertainty of the statistical adjustments,and biased physical relationships among different climate variables due to adjustments in single variable series.

关键词： climate series inhomogeneity homogenization trends in climate series climate extremes

Differences in Soil Microbial Biomass and Activity for Six Agroecosystems with a Management Disturbance Gradient

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2004年第4期14卷 441-448页

作者： ZHANGWei-jian FENGjin-xia j.WU K.PARKER DepartmentofAgronomy NanjingAgriculturalUniversityNanjing210095（China）. DepartmentofPlantPathology NorthCarolinaStateUniversityRaleighNC27695（USA）

Different management practices in six agroecosystems located near Goldsboro, NC, USA were conducted including a successional field (SU), a plantation woodlot (WO), an integrated cropping system with animals (IN), an organic farming system (OR), and two cash-grain cropping systems employing either tillage (CT) or no-tillage (NT) to examine if and how microbial biomass and activity differ in response to alterations in disturbance intensity from six land management strategies. Results showed that soil microbial biomass and activity differed, with microbial activity in intermediately disturbed ecosystems (NT, OR, IN) being significantly higher (P ＜ 0.01) than systems with either high or low disturbance intensities. There was also a significant and a highly significant ecosystem effect from the treatments on microbial biomass C (MBC) (P ＜ 0.05) and on microbial activity (respiration) (P ＜ 0.01), respectively. Multiple comparisons of mean respiration rates distinctly separated the six ecosystem types into three groups: CT ＜ NT, SU and WO ＜ OR and ***, for detecting microbial response to disturbance changes these results indicated that the active component of the soil microbial community was a better indicator than total biomass.

关键词： agroecosystems carbon retention disturbance intensity microbial biomass soil microbial activity

A Tutorial Review of the Solar Power Curve: Regressions, Model Chains, and Their Hybridization and Probabilistic Extensions

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2024年第6期41卷 1023-1067页

作者： Dazhi YANG xiang’ao xia Martin jános MAYER School of Electrical Engineering and Automation Harbin Institute of TechnologyHarbin 150001HeilongjiangChina Key Laboratory for Middle Atmosphere and Global Environment Observation(LAGEO) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Department of Energy Engineering Faculty of Mechanical EngineeringBudapest University of Technology and EconomicsMűegyetem rkp.3Budapest H-1111Hungary

Owing to the persisting hype in pushing toward global carbon neutrality,the study scope of atmospheric science is rapidly *** numerous trending topics,energy meteorology has been attracting the most attention *** essential skill of solar energy meteorologists is solar power curve modeling,which seeks to map irradiance and auxiliary weather variables to solar power,by statistical and/or physical *** this regard,this tutorial review aims to deliver a complete overview of those fundamental scientific and engineering principles pertaining to the solar power *** power curves can be modeled in two primary ways,one of regression and the other of model *** classes of modeling approaches,alongside their hybridization and probabilistic extensions,which allow accuracy improvement and uncertainty quantification,are scrutinized and contrasted thoroughly in this review.

关键词： review energy meteorology solar power curve model chain solar power prediction

Nonlinear Theory of Light Speed Reduction in a Three-Level Λ System

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2001年第8期18卷 1067-1068页

作者： WANG De-Zhong LI Dai-jun LIU xia-j LI Shi-Qun WANG Yu-Zhu Department of Physics Tsinghua UniversityBeijing 100084 Key Laboratory for Quantum Information and Measurements MOEP.R.China Center for Atomic and Molecular Nanosciences Tsinghua UniversityBeijing 100084 Shanghai Institute of Optics and Fine Mechanics Chinese Academy of SciencesShanghai 201800

We present a nonlinear theory of light velocity reduction in a three-levelΛsystem based on electromagnetically induced *** shows that probe field propagates with a velocity that is quite strongly dependent on its intensity instead of being merely approximately dependent on the coupling ***,the minimum group velocity of the probe field is analytically given for a given input power.

关键词： Nonlinear transparency approximate

Pretreating and normalizing metabolomics data for statistical analysis

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

Genes & Diseases 2024年第3期11卷 188-205页

作者： jun Sun Yinglin xia Division of Gastroenterology and Hepatology Department of MedicineDepartment of Microbiology/ImmunologyUIC Cancer CenterUniversity of Illinois ChicagoJesse Brown VA Medical Center Chicago(537)ChicagoIL 60612USA Division of Gastroenterology and Hepatology Department of MedicineUniversity of Illinois ChicagoChicagoIL 60612USA

Metabolomics as a research field and a set of techniques is to study the entire small molecules in biological *** is emerging as a powerful tool generally for pre-cision ***,integration of microbiome and metabolome has revealed the mechanism and functionality of microbiome in human health and ***,metabo-lomics data are very ***/pretreating and normalizing procedures on metabolomics data are usually required before statistical *** this review article,we comprehensively review various methods that are used to preprocess and pretreat metabolo-mics data,including MS-based data and NMR-based data preprocessing,dealing with zero and/or missing values and detecting outliers,data normalization,data centering and scaling,data *** discuss the advantages and limitations of each *** choice for a suitable preprocessing method is determined by the biological hypothesis,the characteristics of the data set,and the selected statistical data analysis *** then provide the perspective of their applications in the microbiome and metabolome research.

关键词： Data centering and scaling Data normalization Data transformation Missing values MS-Baseddata preprocessing NMRData preprocessing Outliers Preprocessing/pretreatment

Thermodynamics and Interfacial Structure of TiAlp/Mg-Li-Al Matrix Composites

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

Thermodynamics and Interfacial Structure of TiAlp/Mg-Li-Al M...

由超拍电子伏特加速器产生的超高能伽马射线气泡

2016中国有色合金及特种铸造发展论坛

作者： xia B.j WANG S.j School of Inner Mongolia University of Technology of Material Science and Engineering

A new MgLiAl matrix composite with 10 wt%TiAl particulates was developed by stir-casting,and its microstructures,properties and chemical compatibility were investigated systematically by XRD,TEM,HREM and material tensile *** results show that,there is a good connection between the Mg-Li matrix and TiAl *** are no detectable chemic products on the interface after fabrication or subsequent heat treatment,and the interface between TiAl and MgLiAl alloy is not weakened after the heat treatment,and the thermodynamic potential for the reaction between the matrix and TiAl particulate is very low,the composite system is stability during fabrication or subsequent heat *** composite has an improved tensile strength compared with matrix alloy,while a good ductility is kept.

关键词： composite chemical compatibility interface

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Science Bulletin 2024年第4期69卷 449-457页

作者： LHAASO Collaboration Zhen Cao Chuandong Gao Cong Li Ruo-Yu Liu Ruizhi Yang 不详 Key Laboratory of Particle Astrophyics&Experimental Physics Division&Computing Center Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Beijing 100049China TIANFU Cosmic Ray Research Center ChengduChina Institute of Frontier and Interdisciplinary Science Shandong UniversityQingdao 266237China School of Astronomy and Space Science Nanjing UniversityNanjing 210023China University of Science and Technology of China Hefei 230026China

We report the detection of aγ-ray bubble spanning at least 100deg2 in ultra-high energy(UHE)up to a few PeV in the direction of the star-forming region Cygnus X,implying the presence super PeVatron(s)accelerating protons to at least 10 PeV.A log-parabola form with the photon indexΓ(E)=(2.71±0.02)+(0.11±0.02)×log10(E/10 TeV)is found fitting the gamma-ray energy spectrum of the bubble *** sources,“hot spots”correlated with very massive molecular clouds,and a quasi-spherical amorphousγ-ray emitter with a sharp central brightening are observed in the *** the core of~0.5°,spatially associating with a region containing massive OB association(Cygnus OB2)and a microquasar(Cygnus X-3),as well as previously reported multi-TeV sources,an enhanced concentration of UHEγ-rays is observed with 2 photons at energies above 1 *** general feature of the bubble,the morphology,and the energy spectrum,are reasonably reproduced by the assumption of a particle accelerator in the core,continuously injecting protons into the ambient medium.

关键词： Cosmic rays γ-rays Interstellar medium Star cluster