检索结果-南通市图书馆

Water and heavy Metal Transport in Roadside Soils

Pedosphere 2005年第6期15卷 746-753页

作者： B. KOChER g. WESSOLEK h. STOFFREgEN Federal highway Research Institute Bruederstraβe 53 51427 Bergisch Gladbach (Germany) Institute of Ecology Department of Soil Protection Technical University of Berlin Salzufer 12 10587 Berlin (Germany)

Roads with very high traffic loads in regions where soils are low in both ph and sorption capacity might be a source of percolation water loaded with heavy metals. Looking at some "worst case" scenarios, this study focused on the input of traffic related pollutants and on Pb, Cd, Cu, Zn, Ni and Cr concentrations in the soil matrix and soil solution, respectively. The analysis also included ph and electrical conductivity and at some sites DOC. The investigations were carried out on sandy soils with more or less low ph values at four motorway sites in germany. The average of daily traffic was about 50 000 up to 90 000 vehicles. Soil pore water was collected in two soil depths and at four distances from the road. The ph in general decreased with increasing distance from the roadside. The elevated ph near the roadside was presumably caused by deposition of dust and weathering residues of the road asphalt, as well as by infiltration of salt that was used during winter time. At these road sites, increased heavy metal concentrations in the soil matrix as well as in the soil solution were found. however, the concentrations seldom exceeded reference values of the german Soil Protection Act. The soil solution concentrations tended to increase from the road edge to 10 m distance, whereas the concentration in the soil matrix decreased. Elevated DOC concentrations corresponded with elevated Cu concentrations but did not substantially change this tendency. high soil water percolation rates were found near the roads. Thus, even low metal concentrations of percolation water could yield high metal loads in a narrow area beside the road.

关键词： heavy metals percolation water roadside soils traffic

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

higher-Order Corrections to Earth's Ionosphere Shocks

引用

Communications in Theoretical Physics 2017年第1期67卷 90-96页

作者： h.g.Abdelwahed E.K.El-Shewy Plasma Technology and Material Science Unit(PTMSU) Physics DepartmentCollege of Science and Humanitarian StudiesPrince Sattam bin Abdulaziz UniversityAlkharjKSA Theoretical Physics group Physics DepartmentFaculty of ScienceMansoura UniversityMansouraEgypt

Nonlinear shock wave structures in unmagnetized collisionless viscous plasmas composed fluid of positive(negative) ions and nonthermally electron distribution are examined. For ion shock formation, a reductive perturbation technique applied to derive Burgers equation for lowest-order potential. As the shock amplitude decreasing or enlarging,its steepness and velocity deviate from Burger equation. Burgers type equation with higher order dissipation must be obtained to avoid this deviation. Solution for the compined two equations has been derived using renormalization analysis. Effects of higher-order, positive- negative mass ratio Q, electron nonthermal parameter δ and kinematic viscosities coefficient of positive(negative) ions η1 and η2 on the electrostatic shocks in Earth's ionosphere are also argued.

关键词： nonthermal electrons ion shock waves Burgers equation Burger type equation renormalization method higher-order dissipation

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

Constructing a taxonomy to support multi-document summarization of dissertation abstracts

引用

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2005年第11期6卷 1258-1267页

作者： KhOO Christopher S.g. gOh Dion h. Division of Information Studies School of Communication & Information Nanyang Technological University 639798 SingaporeDivision of Information Studies School of Communication & Information Nanyang Technological University 639798 Singapore

This paper reports part of a study to develop a method for automatic multi-document summarization. The current focus is on dissertation abstracts in the field of sociology. The summarization method uses macro-level and micro-level discourse structure to identify important information that can be extracted from dissertation abstracts, and then uses a variable-based framework to integrate and organize extracted information across dissertation abstracts. This framework focuses more on research concepts and their research relationships found in sociology dissertation abstracts and has a hierarchical structure. A taxonomy is constructed to support the summarization process in two ways：（1） helping to identify important concepts and relations expressed in the text, and （2） providing a structure for linking similar concepts in different abstracts. This paper describes the variable-based framework and the summarization process, and then reports the construction of the taxonomy for supporting the summarization process. An example is provided to show how to use the constructed taxonomy to identify important concepts and integrate the concepts extracted from different abstracts.

关键词： Text summarization Automatic multi-document summarization Variable-based framework Digital library

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

Electrosorption at metal surfaces from first principles

引用

npj Computational Materials 2020年第1期6卷 517-526页

作者： Nicolas g.hörmann Nicola Marzari Karsten Reuter Chair of Theoretical Chemistry and Catalysis Research Center Technische Universität MünchenGarching 85748Germany Theory and Simulation of Materials(ThEOS) and National Centre for Computational Design and Discovery of Novel Materials(MARVEL)École Polytechnique Fédérale de LausanneLausanne 1015Switzerland Fritz-haber-Institut der Max-Planck-gesellschaft Faradayweg 4-6Berlin 14195Germany

Electrosorption of solvated species at metal electrodes is a most fundamental class of processes in interfacial ***,we use its sensitive dependence on the electric double layer to assess the performance of ab initio thermodynamics approaches increasingly used for the first-principles description of *** show analytically that computational hydrogen electrode calculations at zero net-charge can be understood as a first-order approximation to a fully grand canonical ***,higher-order terms in the applied potential caused by the charging of the double layer include contributions from adsorbate-induced changes in the work function and in the interfacial *** contributions are essential to yield prominent electrochemical phenomena such as non-Nernstian shifts of electrosorption peaks and non-integer electrosorption *** illustrate this by calculating peak shifts for h on Pt electrodes and electrosorption valencies of halide ions on Ag electrodes,obtaining qualitative agreement with experimental data already when considering only second order *** results demonstrate the agreement between classical electrochemistry concepts and a first-principles fully grand canonical description of electrified interfaces and shed new light on the widespread computational hydrogen electrode approach.

关键词： sorption principles canonical

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

Synthesis and Electrochemical Properties of Carbon-Mixed LiEr_(0.02)Fe_(0.98)PO_4 Cathode Material for Lithium-ion Batteries

引用

Journal of Materials Science & Technology 2011年第9期27卷 861-864页

作者： hüseyin gktepe halil Sahan Ahmet lgen Saban Patat Department of Chemistry M krkǒglu Vocational High School University of Erciyes Department of Chemistry Science of Faculty University of Erciyes

LiEr0.02Fe0.98PO4/C composite cathode was synthesized by a simple solution method with polyethylene glycol （PEg） as the reductive agent and carbon source. The effect of erbium doping on the electrochemical behavior of LiFePO4 was studied in this paper. The samples were characterized by X-ray powder diffraction and scanning electron microscopy and the electrochemical properties were investigated by the charge-discharge test. An initial discharge capacity of 149 mAh.g-1 was achieved for the LiEr0.02Fe0.98PO4/C composite cathode with a rate of 0.1 C. The electronic conductivity of Er doped LiFePO4/C was measured as 10-2 ***-1. The results indicated that erbium doping did not destroy the lattice structure of LiFePO4 and enlarge the lattice volume. These changes are beneficial to the improvement of the electrochemical performance of the LiFePO4 cathode.

关键词： LiFePO4 Cathode Erbium doping Lithium batteries

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

On Time-Fractional Cylindrical Nonlinear Equation

引用

Chinese Physics Letters 2016年第11期33卷 62-66页

作者： h.g.Abdelwahed E.K.ElShewy A.A.Mahmoud College of Science and humanitarian Studies Physics DepartmentPrince Sattam Bin Abdul Aziz University Theoretical Physics Research group Physics DepartmentFaculty of ScienceMansoura University

Properties of cylindrical electron acoustic solitons are studied in vortex plasmas. The modil^ea cylindrical Korteweg-de Vries （KdV） equation is acquired and converted into the time fractional cylindrical modified KdV equation by Agrawal＇s analysis. Via the Adomian decomposition method, a cylindrical soliton solution to the equation is obtained. The cylindrical time fractional effect on the wave properties is investigated. Further, the increase of the fractional order of time α and hot to trapped electrons temperature β are minimized in both solitary width and amplitude. These influences on the structures of the soliton may be an alternative to the use of higher order perturbation analysis.

关键词： of is as de et in been form that

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

Microstructures and Mechanical Properties of Al/Mg Alloy Multilayered Composites Produced by Accumulative Roll Bonding

引用

Journal of Materials Science & Technology 2011年第1期27卷 15-21页

作者： h.S. Liu B. Zhang g.P. Zhang Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Key Laboratory for Anisotropy and Texture of Materials of Ministry of Education School of Materials & Metallurgy Northeastern University Shenyang 110004 China

Al/Mg alloy multilayered composites were produced successfully at the lower temperature（280 C） by accumulative roll bonding（ARB） processing *** microstructures of Al and Mg alloy layers were characterized by scanning electron microscopy and transmission electron *** hardness and three-point bending tests were conducted to investigate mechanical properties of the *** is found that Vickers hardness,bending strength and stiffness modulus of the Al/Mg alloy multilayered composite increase with increasing the ARB *** and crack propagation along the interface are the two main failure modes of the multilayered composite subjected to bending *** and fracture mechanisms of the composite are analyzed.

关键词： Accumulative roll bonding(ARB) Al/Mg alloy multilayered composite Ultra-fine grains hardness Bending properties

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

The efect of the couple stress parameter and Prandtl number on the transient natural convection flow over a vertical cylinder

引用

Acta Mechanica Sinica 2013年第5期29卷 649-656页

作者： h.P.Rani g.Janardhana Reddy Chang Nyung Kim Department of Mathematics National Institute of TechnologyWarangal-506004 AP India Department of Mechanical Engineering College of Advanced Technology (Industrial Liaison Research Institute)Kyung Hee UniversityGyeonggi-do 446-701 Korea

An analysis is performed to study transient free convective boundary layer flow of a couple stress fluid over a vertical cylinder, in the absence of body couples. The solution of the time-dependent non-linear and coupled governing equations is carried out with the aid of an unconditionally stable Crank-Nicolson type of numerical scheme. Numerical results for the steady-state velocity, temperature as well as the time histories of the skin-friction coefficient and Nus- selt number are presented graphically and discussed. It is seen that for all flow variables as the couple stress control parameter, Co, is amplified, the time required for reaching the temporal maximum increases but the steady-state decreases.

关键词： Couple stress fluid Natural convection Vertical cylinder Finite difference method

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

Implementation aspects of a phase-field approach for brittle fracture

引用

Frontiers of Structural and Civil Engineering 2019年第2期13卷 417-428页

作者： g.D.hUYNh X.,ZhUANg h.NgUYEN-XUAN Institute of Continuum Mechanics Leibniz-Universitat Hannover30167 HannoverGermany Center for Interdisciplinary Research in Technology Ho Chi Minh CityUniversity of Technology (HUTEH)Ho Chi Minh City Vietnam

This paper provides a comprehensive overview of a phase-field model of fracture in solid mechanics setting. We start reviewing the potential energy governing the whole process of fracture including crack initiation, branching or merging. Then, a discretization of system of equation is derived, in which the key aspect is that for the correctness of fracture phenomena, a split into tensile and compressive terms of the strain energy is performed, which allows crack to occur in tension, not in compression. For numerical analysis, standard finite element shape functions are used for both primary fields including displacements and phase field. A staggered scheme which solves the two fields of the problem separately is utilized for solution step and illustrated with a segment of Python code.

关键词： phase-field modeling FEM staggered scheme fracture

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

Assessment of deterioration in RhA-concrete due to magnesium sulphate attack

引用

International Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 691-696页

作者： g.A. habeeb h.B. Mahmud N.B.A.A. hamid Department of Civil Engineering Faculty of Engineering University of Malaya

The assessment of magnesium sulphate attack on concretes containing rice husk ash （RhA, 20wt% of the cementitious materials） with various average particle sizes was investigated. The total cementitious materials were 390 kg and the water-to-binder ratio （W/B） was 0.53 for all mixtures. Specimens were initially cured in water for 7 d and then immersed in the 3wt% magnesium sulphate solution for up to 111 d of exposure. The specimens were subjected to drying-wetting cycles to accelerate sulphate attack. In addition to the visual monitoring of the specimens, the concrete specimens were subsequently tested for compressive strength, dynamic modulus of elasticity, and length and mass changes. The results show that the specimens exposed to sulphate attack exhibit higher strength and dynamic modulus than those kept in water. The length change is negligible and can be attributed to the normal swelling of concrete. On the other hand, concretes suffers mass loss and surface spalling and softening; the fine RhA-concrete results in a better resistance. For the accelerated sulphate attack method used in this study, mass change and visual monitoring are recommended for assessing the deterioration degree and the effectiveness of supplementary cementitious materials to resist sulphate attack.

关键词： concretes pozzolan ettringite rice husk ash (RhA) magnesium sulphate

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：