检索结果-南通市图书馆

AFM study on the adsorption and aggregation behavior of dissolved humic substances on mica

Science china Chemistry 2006年第3期49卷 256-266页

作者： GE Xiaopeng1, ZHOU Yanmei2. Lü Chunhua1 & TANG Hongxiao1 1. State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, china 2. school of civil engineering & architecture, Beijing {2. university, Beijing 100044, china 1. State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China 2. school of civil engineering & architecture Beijing Jiaotong University Beijing 100044 China

Humic substances constitute the major organic fractions of soils, sediments and natural waters, and play a dominant role in the binding, mobilization, transport and ultimate fate of organic contaminants in subsurface systems. In this paper, two humic acid samples, Guanting and Tianjin, with different origin and chemical compositions have been investigated with AFM imaging for their adsorption and aggregation behaviors on mica. While the Tianjin humic sample is found to form small spheres with 2.0 to 330 nm in diameter at lower concentrations, irregular loop-chain assemblies of hundreds of nanometer in diameter with the chain width of about 40 nm are dominant for the Guanting humic sample, which may attribute to the more polar aliphatic fractions in the chemical composition in the latter. The heterogeneous and polydisperse nature of humic substances with multiple structural features, such as sponge-like structures, perforated sheets, aggregate of spheres, branches and chain-like assemblies etc., is apparent at higher concentrations for both humic samples, showing morphologically new evidence for the dominant view of the humic dual-mode sorption model. With naphthalene introduced, the assemblies of Guanting humic substances clearly become more compact with significantly narrowed branches and less porous the perforated sheet-like structures. It is indica- tive of that smaller nanometer scale rings present along the perforated assemblies could potentially represent hydrophobic domains, which may facilitate the adsorption and aggregation of naphthalene onto the natural particle surfaces and therefore lead to an important role of dissolved humic sub- stances in the sorption of environmental pollutants.

关键词： atomic force microscopy (AFM) dissolved humic substances morphology aggregation adsorption

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 study of adsorption gas sensor based carbon nanotube film

引用

Science china(Technological Sciences) 2005年第4期48卷 372-384页

作者： LI Xin1, LIU Junhua2.& ZHU Changchun1 1. school of Electronic and Information engineering, Xi’an {2. university, Xi’an 710049, china 2. school of Electric engineering, Xi’an {2. university, Xi’an 710049, china 1. school of Electronic and Information engineering Xi’an Jiaotong University 710049 Xi’an China 2. school of Electric engineering Xi’an Jiaotong University 710049 Xi’an China

The study of gas sensitivity of multi-wall carbon nanotubes (MWNTs), which is deposited by low press chemical vapor deposition (LPCVD), is presented. The results show that the pure MWNTs are not sensitive to the gases measured, while the composite film consisting of the MWNTs and silicon dioxide is sensitive to the methane, the hydrogen and the acetylene. The MWNTs and silicon dioxide composite film have the capacitance characteristic because of the formation of Schottky junctions within the MWNTs. The chemistry adsorption of the gas measured on the surface of the MWNTs affects the space discharge area of the Schottky junction, so that the dielectric constant changes with the gas concentration. That is why the gas is sensed.

关键词： gas sensor, carbon nanotubes, low press chemical vapor deposition, scatter.

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

A geometrical and physical nonlinear finite element model for spatial thin-walled beams with arbitrary section

引用

Science china(Technological Sciences) 2010年第3期53卷 829-838页

作者： YANG QingShan 1 &WANG XiaoFeng 2.1 school of civil {2.,Beijing jiaotong university,Beijing 100044,china 2.College of civil {2.,Tongji university,Shanghai 2.0092.china 1. school of civil {2. Beijing Jiaotong University Beijing 100044 China2. College of Civil Engineering Tongji University Shanghai 200092 China

Based on the theories of Bernoulli-Euler beams and Vlasov's thin-walled members,a new geometrical and physical nonlinear beam element model is developed by applying an interior node in the element and independent interpolations on bending angles and warp,in which factors such as traverse shear deformation,torsional shear deformation and their coupling,coupling of flexure and torsion,and second shear stress are all ***,geometrical nonlinear strain in total Lagarange(TL) and the corresponding stiffness matrix are *** plastic model is applied to physical nonlinearity to comply with the yield rule of Von Mises and incremental relationship of *** stiffness matrix is derived by numerical integration on the basis of the finite segment *** show that the developed model is feasible in analysis of thin-walled structures with high accuracy.

关键词： Spatial beams thin-walled structures geometrical and physical nonlinearity finite element arbitrary section

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

Research on nonlinear constitutive relationship of permanent deformation in asphalt pavements

引用

Science china(Physics,Mechanics & Astronomy) 2006年第6期49卷 671-682页

作者： PENG Miaojuan1 & XU Zhihong2.1. Department of civil engineering,Shanghai {2.,Shanghai 2.0072.china 2. school of Transportation engineering,Tongji {2.,Shanghai 2.0092.china 1. Department of civil engineering Shanghai University Shanghai 200072 China 2. school of Transportation engineering Tongji University Shanghai 200092 China

To predict correctly the rut depths in asphalt pavements,a new nonlinear viscoelastic-elastoplastic constitutive model of permanent deformation in asphalt pave-ments is presented. The model combines a generalized Maxwell model with an elasto-plastic one. Then from the creep theory,the linear and nonlinear constitutive equations of the generalized Maxwell model are obtained. From the nonlinear finite element method for the rutting of the asphalt pavement,the rut depths of 4 asphalt-aggregate mixtures are obtained. And the results are compared with the ones from the finite element method by SHRP and the experiments by SWK/UN. The results in this paper are better than the ones by SHRP,and agree with the ones of the experiment by SWK/UN. This shows that the nonlinear viscoelastic-elastoplastic constitutive model,which is presented in this paper for the rutting of the asphalt pavement,is effective. The properties,such as nonlinear elastic-ity,plasticity,viscoelasticity and nonlinear viscoelasticity,which affect the rutting of an asphalt pavement,can be shown in the model. And the characteristics of the permanent deformation of the asphalt pavement can be presented entirely in the model.

关键词： asphalt pavement,permanent deformation,nonlinear viscoelastic-elastoplastic constitutive relationship,generalized Maxwell model,creep compliance.

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

Rock matrix-fractured media model for heterogeneous and fractured coal bed

引用

中国有色金属学会会刊：英文版 2011年第S3期21卷 621-625页

作者： ZHANG Chun-hui1, YU Guang-ming2. ZHANG Chun1 1. school of civil {2., Hebei university of Science and Technology, Shijiazhuang 050018, china 2. school of civil {2., Qingdao Technological university, Qingdao 2.6033, china [a] school of civil {2. Hebei University of Science and Technology Shijiazhuang 050018 China [b] school of civil {2. Qingdao Technological University Qingdao 266033 China

Coal was considered rock matrix-fractured media composed of rock matrix and fractures, and the rock matrix-fractured media model for heterogeneous and fractured coal bed was presented. In this model the rock matrix is heterogeneous, and the mechanical parameters such as elastic modulus and strength follow Weibull distribution. Fractures in coal bed were generated with the discrete fracture network method, and the properties of fractures were simulated with Desai element. Then the virtual generating system (VGS) of natural heterogeneous and fractured coal bed was developed in Matlab 6.0. The coupled model of gas flow and deformation process based on the rock matrix-fractured media model method and VGS for heterogeneous and fractured coal bed was presented, and the numerical code was developed in Matlab 6.0. The gas flow process in the heterogeneous and fractured coal bed was simulated in a numerical case. The main conclusions are: 1) The natural heterogeneous and fractured coal bed could be simulated by the rock matrix-fractured media model and VGS; 2. The fractures connected with the well have much more effects on gas flow than those non-connected.

关键词： heterogeneity fractures rock matrix-fractured media

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

Fracture analysis of a functionally graded interfacial zone between two dissimilar homogeneous materials

引用

Science china(Physics,Mechanics & Astronomy) 2006年第5期49卷 540-552页

作者： CHENG Zhanqi1,2.& ZHONG Zheng1 1. school of Aerospace engineering and Applied mechanics, Tongji {2., Shanghai 2.0092. china 2. College of civil engineering, Zhengzhou {2., Zhengzhou 450002. china 1. school of Aerospace engineering and Applied mechanics Tongji University Shanghai 200092 China 2. College of civil engineering Zhengzhou University Zhengzhou 450002 China

In this paper the plane elasticity problem for a functionally graded interfacial zone containing a crack between two dissimilar homogeneous materials has been considered. It is assumed that in the interfacial zone the reciprocal of the shear modulus is a linear function of the coordinate, while Possion’s ratio keeps constant. By utilizing the Fourier transformation technique and the transfer matrix method, the mixed boundary problem is reduced to a system of singular integral equations that are solved numerically. The influences of the geometric parameters and the graded parameter on the stress intensity factors are investigated. The numerical results show that the graded parameters, the thickness of interfacial zone, the crack size and location have significant effects on the stress intensity factors.

关键词： functionally graded material interfacial zone fracture stress intensity factor

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

Contact position controlling for two-dimensional motion bodies by the boundary element method

引用

Journal of university of Science and Technology Beijing 2002年第2期9卷 138-141页

作者： Junping Pu and Yuanfeng Wang school of civil {2. and architecture, Northern jiaotong university, Beijing 100044, china school of civil {2. and architecture Northern Jiaotong University Beijing 100044 China

An algorithm is presented for controlling two-dimensional motion contact bodies with conforming discretization. Since a kind of special boundary element is utilized in the algorithm, the displacement compatibility and traction equilibrium conditions at nodes can be satisfied simultaneously in arbitrary locations of the contact interface. In addition, a method is also proposed in which the contact boundary location can be moved flexibly on the possible contact boundary. This method is effective to deal with moving and rolling contact problems on a possible larger moving or rolling contact region. Numerical examples show effectiveness of the presented scheme.

关键词： boundary element method contact move roll

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

Cooling effect of ripped-stone embankments on Qing-Tibet railway under climatic warming

引用

Science Bulletin 2003年第6期48卷 598-604页

作者： LAI Yuanming1, ZHANG Luxin1 , ZHANG Shujuan1 & MI Long2.1. State Key Lab. of Frozen Soil engineering, Cold and Arid Regions Environmental and engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000,{2. 2. Department of civil engineering, Northern jiaotong university, Beijing 100044,{2. State Key Lab. of Frozen Soil engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China Department of civil engineering Northern Jiaotong University Beijing China

The heat convection in ballast mass and ripped-stone mass in railway embankments is the problem of heat convection in porous media. In order to calculate the temperature distribution of Qing-Tibet railway embankment, from the governing equations used to study forced convec-tion for incompressible fluids porous media, the finite ele-ment formulae for heat convection in porous media are de-rived by using Galerkin抯 method. The temperature fields of the traditional ballast embankment and the ripped-stone mass embankment, constructed on July 15, have been ana-lyzed and compared under the case that the air temperature in Qinghai-Tibetan Plateau will be warmed up by 2.0℃ in the future 50 years. The calculated results indicate that, the permafrost 5 m below the traditional ballast embankment will be thawed in the regions in which the air yearly-average temperature is larger than -3.5℃ or the yearly-average temperature at the native surface is larger than -1℃. The embankment will cause large thawing settlement. The rail-way embankment will be damaged by permafrost degrada-tion. The ripped-stone mass embankment can not only resist the effect of climatic warm up on it but also provide cool energy for the permafrost under it. It can assure permafrost stability and not subjected to thawing. Therefore, it is highly recommended that the ripped-stone mass embankment be taken as the Qing-Tibet railway embankment structure in high-temperature permafrost regions so that permafrost embankment can be protected as possible as we could.

关键词： cooling effect ripped-stone embankment climatic warming.

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

A novel algorithm of artificial immune system for high-dimensional function numerical optimization

引用

Progress in Natural Science:Materials International 2005年第5期15卷 463-471页

作者： DU Haifeng 1,2.*, GONG Maoguo1, JIAO Licheng1 and LIU Ruochen1(1. Institute of Intelligent Information Processing and Key Laboratory of Radar Signal Processing, Xidian university, Xi'an 710071, china 2. {2. of Mechanical engineering, Xi'an jiaotong university, Xi'an 710049, china) Institute of Intelligent Information Processing and Key Laboratory of Radar Signal Processing Xidian University Xi''an 710071 China school of Mechanical engineering Xi''an Jiaotong University Xi''an 710049 China

Based on the clonal selection theory and immune memory theory, a novel artificial immune system algorithm, immune memory clonal programming algorithm (IMCPA), is put forward. Using the theorem of Markov chain, it is proved that IMCPA is convergent. Compared with some other evolutionary programming algorithms (like Breeder genetic algorithm), IMCPA is shown to be an evolutionary strategy capable of solving complex machine learning tasks, like high-dimensional function optimization, which maintains the diversity of the population and avoids prematurity to some extent, and has a higher convergence speed.

关键词： clonal selection immune memory artificial immune system evolutionary algorithms Markov chain.

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Simulations on Various Lubrication Boundaries between Diamond-like Carbon Films

引用

Journal of Wuhan university of Technology(Materials Science) 2011年第4期26卷 658-660页

作者：兰惠清 school of Mechanical Electronic and Control Engineering Beijing Jiaotong University

Molecular dynamics （MD） simulations were used to study a sliding friction process between DLC films on various boundary conditions. The experimental results revealed that, in the absence of a lubricant, a transfer film between the DLC films was formed. In contrast, when the oil or water lubricants were added to lubricate between the DLC films, a boundary lubrication layer was found. The friction forces on the water and oil lubrication were almost the same, but the friction force in the absence of a lubricant was larger than those on the water and oil lubrication. The conclusions were in good agreement with the experiments.

关键词： lubrication carbon molecular dynamics

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：