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Synthesis of vertically aligned carbon nanotube arrays on silicon substrates

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science{1.(Technological sciences) 2004年第5期47卷 616-624页

作者： ZHENG Ruiting1. CHENG Guoan1. PENG Yibin1. 2. ZHAO Yong1. 3, LIU Huaping1.& LIANG Changlin1.1. Key Laboratory of Radiation Beam Technology and Materials Modification of Ministry of Education, Department of Materials {1. and Engineering, Beijing Normal University, Beijing 1.0875, china {2., civil aviation University of china, tianjin 3.03.0, china 3. Department of Physics, Nanchang University, Nanchang 330047, china Correspondence should be addressed to Zheng Ruiting 1. Key Laboratory of Radiation Beam Technology and Materials Modification of Ministry of Education Department of Materials Science and Engineering Beijing Normal University 100875 Beijing China 2. school of science Civil Aviation University of China 300300 Tianjin China 3. Department of Physics Nanchang University 330047 Nanchang China

The growth of well-aligned carbon nanotube (CNT) arrays using a heat chemical vapor deposition system on silicon substrates is reported. The growth properties of CNT arrays are studied as a function of synthesis conditions. It is found that 750°C and 1. nm Fe film are suitable conditions for the growth of well-aligned CNT arrays. CNT arrays with a uniform diameter, thick tube wall and firm cohesion to the Si substrate can be grown for C2.2.concentration of 2.%. Based on the experiment, the processes of improving the alignment of CNT arrays and cohesion between CNT arrays and Si substrates are discussed.

关键词： carbon nanotubes, vertically aligned, silicon substrate, chemical vapor deposition.

Experimental study on bed-load sediment transport under irregular wave and current combined flow

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Acta Oceanologica Sinica 2001年第2期20卷 271-280页

作者： Wu Yongsheng,Qin Chongren (1. Department of Hydraulic Engineering, Tsinghua University, Beijing 1.0084, china {1. school of {{1. Engineering, tianjin University, tianjin 30007{1. china) Department of Hydraulic Engineering Tsinghua University Beijing 100084 China

Using an irregularly oscillating tray and flume, a series of experiments are completed to evaluate bed-load sediment transport rate under irregular wave -current coexistent field. Testing conditions include three interaction angles 0', 45', 90' and two kinds of median sizes (0.38 and 1.1. mm). The results of transport rate show that the net sediment transport rate can be expressed approximately as the function of the maximum bottom shear stress of waves, mean shear stress of current and the grain size.

关键词： Irregular wave-current bed-load transport rate

Research on nonlinear constitutive relationship of permanent deformation in asphalt pavements

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science{1.(Physics,Mechanics & Astronomy) 2006年第6期49卷 671-682页

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

Research progress of the NSFC Major Research Plan “Dynamic Disaster Evolution of Major Engineering Structures”

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science{1.(Technological sciences) 2010年第2期53卷 592-594页

作者： RU JiPing1. LI DaPeng1. LI ZhongXian2.1.Department of Engineering & Materials {1., NSFC, Beijing 1.0085, china 2.{2. of civil Engineering, tianjin University, tianjin 300072. china 1. Department of Engineering & Materials science NSFC Beijing 100085 China2. School of Civil Engineering Tianjin University Tianjin 300072 China

The NSFC Major Research Plan aims to conduct researches at the international research frontiers on modeling of strong earthquake ground motions and strong wind or typhoon fields, and investigating the damage and failure evolution process of the major engineering structures under dynamic actions, focusing on the following two key scientific problems: (1. characteristics and laws of strong earthquake ground motions and strong wind or typhoon fields, and (2. process and mechanism of dynamic disaster evolution of the major engineering structures. For these goals, the research work is targeted at (1. modeling and predicting of strong earthquake ground motion and strong wind or typhoon fields, (2. identifying critical parameters influencing the dynamic disaster evolution of the major engineering structures, (3) analyzing the whole dynamic disaster evolution process of the major engineering structures, and (4) integration and verification of simulation systems for dynamic disaster evolution of the major engineering structures.

关键词： major engineering structures dynamic disaster evolution research progress

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

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science{1.(Physics,Mechanics & Astronomy) 2006年第5期49卷 540-552页

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

A novel STAP method for the detection of fast air moving targets from high speed platform

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science{1.(Information sciences) 2012年第6期55卷 1259-1269页

作者： WU RenBiao 1.2.JIA QiongQiong 1.& LI Hai 1.1.{1. Key Laboratory for Advanced Signal Processing,civil {2. University of china,{1. 3.03.0,china 2.Intelligent Information Institute of ATR Lab,Shenzhen University,Shenzhen 51.060,china 1. tianjin Key Laboratory for Advanced Signal Processing Civil Aviation University of China Tianjin 300300 China2. Intelligent Information Institute of ATR Lab Shenzhen University Shenzhen 518060 China

Space-time adaptive processing (STAP) is an effective method for detecting moving target in airborne/spaceborne ***,the detection of fast air moving targets from high speed platform is challenged by the range walk of both the clutter and moving *** is well known that keystone formatting can be used to compensate for the range walk of multiple moving targets simultaneously without using the knowledge of the motion ***,in the presence of serious Doppler ambiguity of fast air moving targets,distribution of the clutter will be affected by the keystone formatting matched to the ambiguity number of targets,and as a result the STAP performance will *** this paper,a novel STAP method is proposed for the detection of fast air moving targets from high speed platform,which can deal with the range walk of both clutter and *** of the new method is verified via simulation examples.

关键词： airborne/spaceborne radar keystone formatting space-time adaptive processing (STAP) moving target detection

Power minimization with derivative constraints for high dynamic GPS interference suppression

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science{1.(Information sciences) 2012年第4期55卷 857-866页

作者： WU RenBiao 1.2.LI Chan 1.& LU Dan 1.1.{1. Key Laboratory for Advanced Signal Processing,civil {2. University of china,{1. 3.03.0,china 2.Intelligent Information Institute of ATR Lab,Shenzhen University,Shenzhen,51.060,china 1. tianjin Key Laboratory for Advanced Signal Processing Civil Aviation University of China Tianjin 300300 China2. Intelligent Information Institute of ATR Lab Shenzhen University Shenzhen 518060 China

In this paper,a novel adaptive interference suppression algorithm is proposed for high dynamic GPS (global positioning system) *** new method incorporates derivative constraints on the inter-ference DOA (direction of arrival) into power minimization approach,which could broaden the width of nulls in the interferences directions and adapt to the rapid change of the interference *** with the traditional wide nulling algorithm based on the derivative constraints,the new method does not have to know or estimate the DOAs of the desired signal and the *** new method is firstly discussed in the context of spatial processing,and then extended to space-time adaptive processing to mitigate wideband diffusive multipath *** of the new method is verified via simulation examples.

关键词： GPS interference cancellation adaptive arrays space-time adaptive processing high dynamic GPS receiver

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

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science{1. 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 {1.s, Chinese Academy of {1.s, Beijing 1.0085,{2. 2. school of civil Engineering & Architecture, Beijing Jiaotong University, Beijing 1.0044,{2. 1. State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China 2. {1. 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

Three-dimensional elasticity solution of simple-supported rectangular plate on point supports, line supports and elastic foundation

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science{1.(Technological sciences) 2009年第3期52卷 584-589页

作者： XU YePeng1.& ZHOU Ding2.1.{1. of science, Nanjing University of science and Technology, Nanjing 2.0094, china 2.College of civil Engineering, Nanjing University of Technology, Nanjing 2.0009, china 1. school of {1. Nanjing University of Science and Technology Nanjing 210094 China 2. College of {1. Engineering Nanjing University of Technology Nanjing 210009 China

This paper studies the bending of simple-supported rectangular plate on point supports, line supports and elastic foundation. On the basis of three-dimensional elasticity theory, the exact expressions of the displacement functions, which satisfy the governing differential equations and the simply supported boundary conditions at four edges of the plate, are analytically derived. The reaction forces of the in- termediate supports are regarded as the unknown external forces acting on the lower surface of the plate. The unknown coefficients are then determined by the boundary conditions on the upper and lower surfaces of the plate. Comparing the numerical results obtained from the proposed method to those obtained from Kirchhoff plate theory, Mindlin plate theory and those obtained from the commer- cial finite element software ANSYS, the high accuracy of the present method has been demonstrated.

关键词： rectangular plate point support line support elastic foundation displacement stress three-dimensional elasticity solution