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Adsorption and adhesion of blood proteins and fibroblasts on multi-wall carbon nanotubes

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Science China(Life Sciences) 2009年第5期52卷 479-482页

作者： LI DeJun1, YUAN Li1, YANG Ying1, DENG XiangYun1, Lü XiaoYing2, HUANG Yan2, CAO Zheng2, LIU Hao3 & SUN XueLiang3 1 College of Physics and Electronic Information Science, Tianjin Normal University, Tianjin 300074, China 2 State Key Laboratory of Bioelectronics, Southeast University, Nanjing 210096, China 3 department of mechanical & materials engineering, University of western ontario, london, ON, canada College of Physics and Electronic Information Science Tianjin Normal University Tianjin 300074 China State Key Laboratory of Bioelectronics Southeast University Nanjing 210096 China department of mechanical & materials engineering University of Western Ontario London ON Canada

This article concerns the investigation of blood protein adsorption on carbon paper and multi-wall carbon nanotubes (MWCNTs). Mouse fibroblast cell adhesion and growth on MWCNTs was also studied. The results showed that fibrinogen adsorption on carbon paper was much lower than that on MWCNTs, which means that platelets readily aggregate on the surface of MWCNTs. Mouse fibroblast cells implanted on MWCNTs tended to grow more prolifically than those implanted on carbon paper. The cell concentration observed on MWCNTs increased from 1.2×105/mL for a single day culture to 2×105/mL for a 7-day culture. No toxicity reaction was observed during the culturing period. These results indicated that MWCNTs possessed excellent tissue compatibility.

关键词： multi-wall carbon nanotubes cell adhesion protein adsorption toxicity tissue compatibility

Crank conditions and rotatability of 3-RRR planar parallel mechanisms

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Science China(Technological Sciences) 2009年第12期52卷 3601-3612页

作者： LI RuiQin 1 &DAI Jian S 2 1 College of mechanical engineering and Automation,North University of China,Taiyuan 030051,China 2.department of mechanical engineering,King’s College london,University of london,WC2R 2LS,UK College of mechanical engineering and Automation North University of China Taiyuan 030051 China department of mechanical engineering King’s College London University of London WC2R 2LS London UK

This paper investigates the rotatability of planar parallel mechanisms by revealing the crank conditions that relate to link *** paper extends the theorem of assemblability and the rotatability criterion and applies these criteria to parallel mechanisms in investigating the crank conditions of a parallel mechanism,leading to classification of three types of crank existing conditions including three-crank’s,six-crank’s and nine-crank’s of 3-RRR planar parallel *** results are summarized as constraint conditions in relation with link parameters with a concluding table and case studies.

关键词： crank rotatability planar parallel mechanism

Orientation angle rotatability of planar serial n-link manipulators

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Science China(Technological Sciences) 2010年第6期53卷 1620-1637页

作者： LI RuiQin1,XIAO DengHong1 & DAI Jian S2 1 College of mechanical engineering and Automation,North University of China,Taiyuan 030051,China 2.department of mechanical engineering,King’s College london,University of london,london WC2R 2LS,UK 1. College of mechanical engineering and Automation North University of China Taiyuan 030051 China2. Department of Mechanical Engineering King’s College London University of London London WC2R 2LS UK

This paper presents a new method of analyzing the orientation angle rotatability of a planar serial n-link manipulator by examining the rotatability of its virtual equivalent *** orientation boundary region decomposition is proposed based on the polynomial discriminant derived from a serial three-link *** angle workspace indicates a set of angle ranges by which the end-effector can reach with certain orientation for every point in the reachable position *** introducing a virtual equivalent mechanism,the open-chain kinematic problem is converted into a close-chain mechanism,and the Grashof-type condition is used to examine the rotatability of the end-effector *** reachable position workspace can be divided into several Grashof intervals and non-Grashof intervals based on the extreme positions and singular configurations of a *** derived equations in this paper can be used to calculate the variation rule of the orientation angle workspace of any given planar serial n-link manipulator on the basis of its link *** orientation angle rotatability of a seven-link serial manipulator is solved by the proposed method and graphical representations of the orientation angle workspaces are mapped onto a three-dimensional coordinate *** theoretical approach has practical significance for the design of a highly dexterous serial n-link manipulator with proposed link relations.

关键词： Grashof criterion planar serial manipulator orientation angle workspace virtual equivalent mechanism

GAS-SOLIDS FLOW BEHAVIOR WITH A GAS VELOCITY CLOSE TO ZERO

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Particuology 2006年第Z1期 167-177页

作者： H. Zhang and J.-X. Zhu* department of Chemical engineering, University of western ontario, london, ontario, canada N6A 5B9, canada

In a 9.3 m high and 0.10 m i.d. gas-solids downflow fluidized bed (downer), the radial and axial distribu- tions of the local solids holdups and particle velocities along the downer column were measured with the superficial gas velocity set to zero. A unique gas-solids flow structure was found in the downer system with zero gas velocity, which is completely different from that under conditions with higher gas velocities, in terms of its radial and axial flow structures as well as its micro flow structure. The gas-solids flow pattern under zero gas velocity conditions, together with that under low gas velocity conditions, can be considered as a special regime which differs from that under higher gas velocity conditions. According to the hydrodynamic properties of the two regimes, they can be named the “dense annulus” regime for the flow pattern under zero or low gas velocity conditions and the “dense core” regime for that under higher gas ve- locity conditions.

关键词： downer reactor gas-solids cocurrent downflow fluidized bed hydrodynamics flow development particle velocity solids holdup solids flux flow regime

Advances in numerical methods for the solution of population balance equations for disperse phase systems

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Science China Chemistry 2009年第8期52卷 1063-1079页

作者： SU JunWei1,GU ZhaoLin2,3 & XU X.Yun41 department of mechanical engineering and Automation,School of mechanical engineering,Xi’an Jiaotong University,Xi’an 710049,China 2 Key Laboratory of Mechanics on Disaster and Environment in western China,Ministry of Education,Lanzhou 730000,China 3 department of Environmental Science and Technology,School of Human Settlements and Civil engineering,Xi’an Jiaotong University,Xi’an 710049,China 4 department of Chemical engineering,Imperial College london,london SW7 2AZ,UK 1. department of mechanical engineering and Automation School of Mechanical Engineering Xi’an Jiaotong University Xi’an 710049 China 2. Key Laboratory of Mechanics on Disaster and Environment in western China Ministry of Education Lanzhou 730000 China 3. department of Environmental Science and Technology School of Human Settlements and Civil Engineering Xi’an Jiaotong University Xi’an 710049 China 4. department of Chemical engineering Imperial College London London SW7 2AZ UK

Accurate prediction of the evolution of particle size distribution is critical to determining the dynamic flow structure of a disperse phase system.A population balance equation(PBE),a non-linear hyperbolic equation of the number density function,is usually employed to describe the micro-behavior(aggregation,breakage,growth,etc.) of a disperse phase and its effect on particle size *** solution is the only choice in most *** this paper,three different numerical methods(direct discretization methods,Monte Carlo methods,and moment methods) for the solution of a PBE are evaluated with regard to their ease of implementation,computational load and numerical *** attention is paid to the relatively new and superior moment methods including quadrature method of moments(QMOM),direct quadrature method of moments(DQMOM),modified quadrature method of moments(M-QMOM),adaptive direct quadrature method of moments(ADQMOM),fixed pivot quadrature method of moments(FPQMOM),moving particle ensemble method(MPEM) and local fixed pivot quadrature method of moments(LFPQMOM).The prospects of these methods are discussed in the final section,based on their individual merits and current state of development of the field.

关键词： population balance equation direct discretization method Monte Carlo method moment methods disperse phase system

CRITERION　OF　STOCHASTIC　LAYER　NEAR　A　PLANAR　HOMOCLINIC　ORBIT　OF　NONLINEAR　DYNAMICAL　SYSTEM

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Journal of Hydrodynamics 1995年第2期7卷 35-50页

作者： Albert C. J. Luo(department of mechanical & Industrial engineering University of Manitoba. Winnipeg, Manitoba, R3T 2N2,canada) Univ of Manitoba Winnipeg Canada

A new analytic method is developed for nonlinear dynamical system, to investigate the mathematical structure and physical characteristics of the stochastic layer near a homoclinic or heteroclinic orbit. This method is based on the subharmonic resonant condition and an energy increment along the separatrix of the system. The critical conditions for the disappearance of stochastic layer are presented, which are associated with all control parameters of the system including initial conditions, excitation frequencies excitatiom amplitudes ***, using this method, we analyze two simple nonlinear dynamical systems, namely,Duffing-Holmes's equation and a forced planar pendulum. As their stochastic layers begin to disappear, their critical amplitudes are also obtained for the given excitation frequency and other chosen parameters. By means of these conditions, we carry out numerical simulations for the two simple models. Their stochastic layer will be shown using Poincare mapping section. Our theoretical results are subeequently shown to be in a good agreement with numerical simulations.

关键词： nonlinear dynamical system stochastic layer numerical simulation

Rolling Element Bearing Diagnostics by Combination of Envelope Analysis and Wavelet Transform

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Journal of University of Science and Technology Beijing 2001年第1期8卷 69-74页

作者： Ying Tang, Qiao Sun mechanical engineering School, University of Science and Technology Beijing, Beijing 100083, China department of mechanical engineering, University of Calgary Calgary Alberta T2N 1N4, canada Univ Sci & Technol Beijing Sch Mech Engn Beijing 100083 Peoples R China Univ Calgary Dept Mech Engn Calgary AB T2N 1N4 Canada

Rolling element-bearing diagnostics has been studied over the last thirty years, and envelope analysis is widely recognized as being the best approach for detection and diagnosis of rolling element bearing incipient failure. But one of the on-going difficulties with envelope technique is to determine the best frequency band to envelop. Here, wavelet transform technique is introduced into envelope analysis to solve the problem by capturing bearing defects-sensory scales (i.e. frequency bands). A modulated Gaussian function is chosen to be the analytical wavelet because it coincides well with bearing defect-induced vibration signal patterns. Vibration signals measured from railway bearing tests were studied by the proposed method. Cases of bearings with single and multiple defects on inner and outer race under different testing conditions are presented. Experimental results showed that the proposed method allowed a more accurate local description and separation of transient signal part, which were caused by impacts between defects and the mating surfaces in the bearing. The combination method provides an effective signal detection technique for rolling element-bearing diagnostics.

关键词： continuous wavelet transform envelope analysis rolling element bearing diagnostics

Simple geometrical explanation of Gurtin-Murdoch model of surface elasticity with clarification of its related versions

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Science China(Physics,Mechanics & Astronomy) 2010年第3期53卷 536-544页

作者： Ru C. Q. department of mechanical engineering, University of Alberta, Edmonton, Alberta, canada T6G 2G8 1. department of mechanical engineering University of Alberta Edmonton Alberta Canada T6G 2G8

It is showed that all equations of the linearized Gurtin-Murdoch model of surface elasticity can be derived, in a straightforward way, from a simple second-order expression for the ratio of deformed surface area to initial surface area. This elementary derivation offers a simple explanation for all unique features of the model and its simplified/modified versions, and helps to clarify some misunderstandings of the model already occurring in the literature. Finally, it is demonstrated that, because the Gurtin-Murdoch model is based on a hybrid formulation combining linearized deformation of bulk material with 2nd-order finite deformation of the surface, caution is needed when the original form of this model is applied to bending deformation of thin-walled elastic structures with surface stress.

关键词： surface elasticity surface stress Gurtin-Murdoch model

Enhancing the capacitances of electric double layer capacitors based on carbon nanotube electrodes by carbon dioxide activation and acid oxidization

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Science China(Technological Sciences) 2010年第5期53卷 1234-1239页

作者： LI ChenSha1,2,QIAO YingJie1,WU JianJun2,WANG DaZhi2 & YUAN DianBo2 1 department of materials Science,Harbin engineering University,Harbin 150001,China 2.department of mechanical engineering,Tsinghua University,Beijing 100084,China 1. department of materials Science Harbin Engineering University Harbin 150001 China2. Department of Mechanical Engineering Tsinghua University Beijing 100084 China

Polarizable electrodes of electric double layer capacitors(EDLCs) were made from carbon nanotubes(CNTs).Effect of carbon dioxide activation together with acid oxidation for the electrodes on the characteristics and performances of electrodes and EDLCs was *** dioxide activation changed the microstructure of the electrodes,increased the effective surface area of CNTs and optimized the distribution of apertures of the *** oxidization modified the surface characteristics of *** on the polarizable electrodes treated by carbon dioxide activation and acid oxidization,the performances of EDLCs were greatly *** specific capacitance of the electrodes with organic electrolyte was increased from 21.8 F/g to 60.4 F/g.

关键词： carbon nanotube electric double layer capacitor scan electron microscopy