检索结果-南通市图书馆

water Security Problem in North china: Research and Perspective

Pedosphere 2005年第5期15卷 563-575页

作者： XIA Jun LIU Meng-Yu JIA Shao-Feng Key Laboratory of water Cycle ＆Related Land Surface Processes Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 （China） State Key Laboratory of water resources ＆ {2. engineering Sciences Wuhan University Wuhan 430072（China） Center for Agricultural resources Research Institute of Genetic and Developmental Biology Chinese Academy of Sciences Shijiazhuang 050021 （China）

This paper addresses the emergence of water security problems in North china with the aim of highlighting key waterresources management and water security issues for the long-term development of North china. Three key problemsrelated to water resources and security issues in North china in the 2.st century are addressed, namely 1) the watercycle under environmental change, 2. agricultural water saving, and 3) water security. Development of internationalresearch related to these issues is also reviewed. The research plan developed recently by the Chinese Academy of Sciences(CAS) is discussed and suggestions on research and development of water resources science in North china are *** to focus on experimental catchments and dedicated research stations, a detailed knowledge of the water cycle onNorth china farmland has been compiled. A range of techniques that include isotope tracers has been used to acquirehydrologic data. Much research has been devoted to developing distributed hydrological models at different scales. In thewell irrigation district, five different water saving irrigation regimes have been investigated, and these regimes have hadwidespread application, and reduced water use 60-150 mm while they increased water use efficiency (WUE) by 2.%-30%.Furthermore, preventing water pollution is the most essential step to ensure North china’s water security.

关键词： environmental change North china water cycle water resources water security

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

Variational iteration method for solving time-fractional diffusion equations in porous the medium

引用

Chinese Physics B 2012年第12期21卷 118-122页

作者：吴国成 Key Laboratory of Numerical Simulation of Sichuan Province Neijiang Normal UniversityNeijiang 641112China college of water {2. and hydropower Sichuan UniversityChengdu 610065China

The variational iteration method is successfully extended to the case of solving fractional differential equations, and the Lagrange multiplier of the method is identified in a more accurate way. Some diffusion models with fractional derivatives are investigated analytically, and the results show the efficiency of the new Lagrange multiplier for fractional differential equations of arbitrary order.

关键词： time-fractional diffusion equation Captuo derivative Riemann-Liouville derivative,variational iteration method Laplace transform

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

Simultaneous Recrystallization and Oxidation Behavior of Mn-Containing IF Steel

引用

Journal of Iron and Steel Research International 2012年第8期19卷 67-74页

作者： ZHANG Zuo-tai, ZHANG Ying-yi (Department of Energy and resources engineering, {2. of engineering, Peking university, Beijing 100871, china) Department of Energy and resources engineering College of Engineering Peking University Beijing 100871 China

The recrystallization and oxidation of a Mn-containing interstitial free (IF) steel were investigated simultaneously using confocal scanning laser microscope (CSLM) under controlled atmosphere of Ar 95% and H2.5% (in volume percent) at different temperatures. It was found that the grain boundary played a significant role in controlling recrystallization and oxidation in overall oxidation kinetics of the steel. The surface morphology was composed of two networks along the original and new grain boundaries respectively, which did not coexist. The grain boundary moved in different directions with different velocities during annealing process. The recrystallization processes were studied by CSLM motion video through observing the moving grain boundary to estimate the time for 50% recrystallization, and the activation energy for recrystallization was therefore calculated. The oxidation mechanism was discussed through comparison of the fluxes among mass transfer of water vapor, dissociation of water vapor and outward diffusion alloying elements. The results indicated that the oxidation was controlled by the mass transfer from the bulk gas to the surface, or dissociation rate, or outward diffusion of manganese, which depended on the temperature to form a grain boundary ridge or groove.

关键词： IF steel oxidation recrystallization grain boundary

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

Hardfill坝地震动力响应的比较分析

引用

水电能源科学 2010年第2期28卷 85-88页

作者：裴镔武汉大学水利水电学院湖北武汉430072

针对Hardfill坝具有高抗震性和高安全性的优势,基于大型有限元软件ADINA,分别运用附加质量法和流固耦合理论并辅以空库时大坝的动力特性,比较分析了Hardfill坝地震动力响应。结果表明,两种方法求得的坝体自振频率基本相同,但以附加质量... 详细信息

针对Hardfill坝具有高抗震性和高安全性的优势,基于大型有限元软件ADINA,分别运用附加质量法和流固耦合理论并辅以空库时大坝的动力特性,比较分析了Hardfill坝地震动力响应。结果表明,两种方法求得的坝体自振频率基本相同,但以附加质量模型为基础的坝体动力响应大于用流固耦合理论求得的数值。故用附加质量法分析Hardfill坝的地震动力响应基本可行,但计算结果较保守。

关键词：水工结构地震动力响应附加质量流固耦合 ADINA Hardfill坝

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

Element geochemistry and cleaning potential of the No. 11 coal seam from Antaibao mining district

引用

Science china Earth Sciences 2005年第12期48卷 2142-2154页

作者： WANG Wenfeng1, QIN Yong1, SONG Dangyu2. SANG Shuxun1, JIANG Bo1, ZHU Yanming1 & FU Xuehai1 1. college of resources & Geosciences, {2. university of Mining and Technology, Xuzhou 2.1008, {2. 2. State Key Laboratory of Coal Combustion, Huazhong university of Science and Technology, wuhan 430074, {2. 1. college of resources & Geosciences China University of Mining and Technology 221008 Xuzhou China 2. State Key Laboratory of Coal Combustion Huazhong University of Science and Technology 430074 Wuhan China

Based on the analyses of sulfur and 41 other elements in 8 channel samples of the No. 11 coal seam from Antaibao surface mine, Shanxi, china and 4 samples from the coal preparation plant of this mine, the distribution of the elements in the seam profile, their geo-chemical partitioning behavior during the coal cleaning and the genetic relationships between the both are studied. The conclusions are drawn as follows. The coal-forming environment was probably invaded by sea water during the post-stage of peatification, which results in the fact that the contents of As, Fe, S, etc. associated closely with sea water tend to increase toward the top of the seam, and that the kaolinite changes into illite and montmorillonite in the coal-sublayer near the roof. These elements studied are dominantly associated with kaolinite, pyrite, illite, montmorillonite, etc., of which the As, Pb, Mn, Cs, Co, Ni, etc. are mainly associated with sulfides, the Mo, V, Nb, Hf, REEs, Ta etc. mainly with kaolintie, the Mg, Al etc. mainly with epigenetic montmorillonite, and the Rb, Cr, Ba, Cu, K, Hg, etc. mainly with epigenetic illite. The physical coal cleaning is not only effective in the removal of ash and sulfur, but also in reducing the concentra-tion of most major and trace elements. The elements Be, U, Sb, W, Br, Se, P, etc. are largely or partly organically bound showing a relatively low removability, while the removability of the other elements studied is more than 2.%, of which the Mg, Mn, Hg, Fe, As, K, Al, Cs, and Cr associ-ated mostly with the coarser or epigenetic minerals show a higher removability than that of ash. The distribution of the elements in the seam profile controls their partitioning behavior to a great degree during the coal cleaning processes.

关键词： Antaibao mining district, No.11 coal seam, element geochemistry, cleaning.

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

CHARACTERISTIC ANALYSIS OF THE PLUNGING OF TURBIDITY CURRENTS

引用

Journal of Hydrodynamics 2010年第2期22卷 274-282页

作者： AN Rui-dong LI Jia State key Laboratory of Hydraulics and Mountain River engineering Sichuan University Chengdu 610065China college of water Recourse and {2. Sichuan University Chengdu 610065 China

Turbidity currents are flows driven by suspended sediment of flood-induced turbid river water with excess *** currents are often the governing factor in reservoir sedimentation by transporting fine materials over long distances and delivering the majority of deposition,which thus reduces the storage ***,the design and operation of a reservoir requires an accurate prediction of its occurrence condition and plunging position,which is the objective of the present *** article presents a verified algebraic slip mixture model including momentum,continuity and algebraic velocity expressions to simulate 2.D turbidity *** experiments in a multiphase flume were carried *** number,sediment concentration and densimetric Froude number were used as parameters in the occurrence condition *** plunging of turbidity currents may produce reflux and backflow due to the diving flow at the surface of the clear *** similar experimental results were also obtained by PIV measurements

关键词： turbidity current plunge suspend sediment algebraic slip mixture model densimetric Froude number

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

DISTRIBUTION OF BIOAVAILABLE PHOSPHORUS BETWEEN OVERLYING water AND SPM UNDER ABRUPT EXPANSION CONDITION

引用

Journal of Hydrodynamics 2011年第3期23卷 398-406页

作者： WAN Jun WANG Ze QIAN Shu-qin college of water Conservancy and {2. engineering Hohai University Nanjing 210098 China college of Mechanics and Materials Hohai University Nanjing 210098 China Institute of Pearl River water Research Guangzhou 510611 China

Experiments on Phosphorus （P） fraction characteristics in sediment resuspension were performed under adequate hydrodynamic conditions. It is found that the concentration of Suspended Particulate Matter （SPM） in the eddy current region exhibits the ＂Matthew effect＂. Velocity is an impact factor of the Equilibrium Phosphate Concentration （EPC）, which is related to other hydraulic conditions. Overall bioavailable dissolved P in the SPM causes migration to overlying water and sediment, eventually being converted into a chemical speciation of P. Conditions of resuspension promote A1-P of SPM that migrated to the sediment and water. Concentrations of A1-P in SPM are reduced. P is released from SPM to water bodies, mainly through conversion into particulate P and dissolved total P. Meanwhile, exchange between SPM and sediments occur mainly through Ca-P migration. A1-P and BD-P possess similar geochemical characteristics or source. Ca-P and A1-P exhibit a negative correlation between migration and conversion.

关键词： bioavailable phosphorus Suspended Particulate Matter (SPM) abrupt expansion flow resuspension

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

NUMERICAL SIMULATION OF LEVEE BREACH FLOWS UNDER COMPLEX BOUNDARY CONDITIONS

引用

Journal of Hydrodynamics 2009年第5期21卷 633-639页

作者： YU Ming-hui DENG Yin-ling QIN Lian-chao WANG Dang-wei CHEN Ya-ling State Key Laboratory of water resources and {2. engineering Science Wuhan University Wuhan 430072 China

Levee or dam failure can cause a significant disaster in most cases. A good prediction of the flood process especially in a real complex terrain is necessary for working out emergency plans for levee or dam breaches. Numerical simulations of levee or dam breach flow were carried out often with constant flow parameters and in relatively simple channels rather than in natural rivers with complex boundaries. This article presents our dedicated studies on the 2.D numerical model of levee or dam breach hydraulics with finite difference schemes. The good performance of the model is demonstrated by comparisons with the theoretical solution of an idealized dam-break flow over a frictionless flat rectangular channel. The model is also validated through its stability and conservation properties. The model is applied to simulate the flood propagation under complex boundary conditions, and the unsteady flood process in a river and in the dry floodplain with a complex bed terrain simultaneously. Furthermore, with respect to engineering practice, the numerical solutions can give special guidance to the effects of parameters such as the flood depth at different sites and the inundated area at different time periods after the levee breach and the travel time of the flood waves, which may be very important for practicing engineers in an efficient flood management.

关键词： numerical simulation levee breach unsteady flood process complex boundary condition

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

HYDRAULIC CHARACTERISTICS OF PARTIAL OPENING OF THE WORKING GATE FOR A DISCHARGE TUNNEL

引用

Journal of Hydrodynamics 2007年第4期19卷 488-493页

作者： WU Jian-hua FENG Shu-rong WU Wei-wei RUAN Shi-ping college of water Conservancy and {2. engineering Hohai University Nanjing 210098 China china Hydro Mid-South Design and Research Institute Changsha 410014 China

The partial opening of the working gate for a discharge tunnel is used more and more widely in the various conditions, such as releasing discharge to meet the needs of the various stages under construction, or of the operations at low reservoir levels. In this article the hydraulic characteristics were investigated of the partial opening of the working gate based on the physical model experiments of the discharge tunnel for the Longtan hydropower Project, including the discharge coefficient, the surface profile of the free flow section, the bottom pressure distribution of the tunnel with an aerator, the cavity length just from the ramp, and the wall pressure of the curve section of the outlet. Some new issues were discussed and the properties were presented of the partial opening of the gate.

关键词： partial opening hydraulic characteristics working gate discharge tunnel

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

NUMERICAL STUDY OF FLOW AND DILUTION BEHAVIOR OF RADIAL WALL JET

引用

Journal of Hydrodynamics 2010年第5期22卷 681-688页

作者： LI Zhi-wei HUAI Wen-xin QIAN Zhong-dong ZENG Yu-hong YANG Zhong-hua State Key Laboratory of water resources and {2. engineering Science Wuhan University Wuhan 430072 China

The radial wall jet is a flow configuration that combines the radial jet and the wall jet. This article presents a simulation of the radial wall jet by applying the transition Shear-Stress Transport （ SST） model. Tanaka’s experimental data are used for validation. The computed velocity profiles agree well with the experimental ones. The distributions of the velocity on cross-sections show a similarity in the main region and the profiles are different with those of the free radial jet or the wall jet, because the presence of the wall limits the expansion of the jet. By introducing the equivalent nozzle width, the maximum velocity decays and the half-width distributions are normalized, respectively. In addition to compare the flow field with experiments, this paper also analyzes the dilution effect of radial wall jets in terms of the concentration distributions. The concentrations on the wall keep constant within a certain distance from the nozzle. And the concentration distributions also show a similarity in the main region. Both the decays of the maximum concentration and the distributions of the concentration half-width fall into a single curve, respectively. The dilution effect of radial wall jets is thus verified.

关键词： radial wall jet velocity profile concentration distribution concentration half-width

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：