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Two-dimensional thermoelasticity solution for functionally graded thick beams

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Science china(Physics,mechanics & Astronomy) 2006年第4期49卷 451-460页

作者： Lü Chaofeng1, CHEN Weiqiu1 & ZHONG Zheng2 1. department of Civil engineering, zhejiang university, hangzhou 310027, china 2. Key Laboratory of Solid mechanics of Ministry of Education, School of Aerospace engineering and Ap- plied mechanics, Tongji university, Shanghai 200092, china department of Civil engineering Zhejiang University Hangzhou China Key Laboratory of Solid mechanics of Ministry of Education School of Aerospace Engineering and Applied Mechanics Tongji University Shanghai China

Two-dimensional thermoelasticity analysis of functionally graded thick beams is presented using the state space method coupled with the technique of differential quadrature. Material properties vary continuously and smoothly through the beam thickness, leading to variable coefficients in the state equation derived from the elasticity equations. Approximate laminate model is employed to translate the state equation into the one with constant coefficients in each layer. To avoid numerical instability, joint coupling matrices are introduced according to the continuity conditions at interfaces in the approximate model. The differential quadrature procedure is applied to discretizing the beam in the axial direction to make easy the treatment of arbitrary end conditions. A simply-supported beam with exponentially varying material properties is considered to validate the present method. Numerical examples are performed to investigate the influences of relative parameters.

关键词： state equation differential quadrature approximate laminate model joint coupling matrices thermal stresses.

In-situ Synthesis of ZSM-5 Zeolite from Metakaolin/Spinel and Its Catalytic Performance on Methanol Conversion

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china Petroleum Processing & Petrochemical Technology 2010年第1期12卷 23-28页

作者： Liu Ye Yu Xianbo Qin Lei Wang Jingdai Yang Yongrong (department of Chemical and Biochemical engineering,zhejiang university,hangzhou 310027) department of Chemical and Biochemical engineering Zhejiang University Hangzhou 310027 China

ZSM-5 zeolite was in-situ synthesized from metakaolin or s alumina sources, respectively. The ZSM-5 zeolite was characterized pinel by incorporating additional silica and by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared （FT-IR） spectroscopy and N2 adsorption measurement. This supported zeolite was tested on the methanol to propylene （MTP） processes. Experimental results showed that the ZSM-5 zeolite exhibited high selectivity for propylene. The yield of propylene on ZSM-5 zeolite made from metakaolin was increased by 17.73%, while that on ZSM-5 zeolite made from spinel was raised by 9.90%, compared to that achieved with the commercial ZSM-5 zeolite. The significant increase in propylene production is probably due to the distinctive morphology of the ZSM-5 zeolite, which possessed a rough external surface covered with sphere-like particles and distribution of small crystals sized at around 400--500 nm. This morphology could help to generate more crystal defects so that more active centers could be exposed to the reaction mixture. In addition, the zeolite product had a gradient pore distribution and many medium Brǒnsted acid sites, both of which might also contribute to the increased propylene production.

关键词： metakaolin spinel in-situ synthesis of ZSM-5 methanol to propylene (MTP)

MARCHING CUBES BASED FRONT TRACKING METHOD AND ITS APPLICATION TO SOME INTERFACE INSTABILITY PROBLEMS

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Journal of Hydrodynamics 2011年第5期23卷 580-588页

作者： WANG Jing-yi ZOU Jian-feng ZHENG Yao REN An-lu 不详 department of engineering mechanics School of Aeronautics and Astronautics Zhejiang University Hangzhou 310027 China

A front tracking method based on a marching cubes isosurface extractor, which is related filter generating isosurfaces from a structured point set, is provided to achieve sharp resolution for the simulation of non-diffusive interfacial flow. Compared with the traditional topology processing procedure, the current front tracking method is easier to be implemented and presents high performance in terms of computational resources. The numerical tests for 2-D highly-shearing flows and 3-D bubbles merging process are conducted to numerically examine the performance of the current methodology for tracking interfaces between two immiscible fluids The Rayleigh-Taylor （RT） and Richtmyer-Meshkov （RM） instability problems are successfully investigated with the present marching cubes based front tracking method.

关键词： interracial flow front tracking marching cubes bubbles merging process Rayleigh-Taylor (RT) instability Richtmyer- Meshkov (RM) instability

Optical transfer function analysis of circular-pupil wavefront coding systems with separable phase masks

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Chinese Physics B 2012年第6期21卷 200-206页

作者：赵廷玉刘钦晓余飞鸿 department of Physics Zhejiang Sci-Tech University Optical engineering department Zhejiang University

This paper proposes a simple method to achieve the optical transfer function of a circular pupil wavefront coding system with a separable phase mask in Cartesian coordinates. Based on the stationary phase method, the optical transfer function of the circular pupil system can be easily obtained from the optical transfer function of the rectangular pupil system by modifying the cut-off frequency and the on-axial modulation transfer function. Finally, a system with a cubic phase mask is used as an example to illustrate the way to achieve the optical transfer function of the circular pupil system from the rectangular pupil system.

关键词： wavefront coding circular pupil separable phase mask stationary phase method

NUMERICAL SIMULATION OF FREE MIXING LAYER WITH CROSS SHEAR

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Chinese Journal of Aeronautics 1997年第1期10卷 14-17页

作者： Lin Jianzhong Wang Canxing Li Feng(department of mechanics, State Key Laboratory of Fluid Power Transmissionand Control, zhejiang university, hangzhou, 310027, china) department of mechanics State Key Lab. Fluid Pwr. T. Zhejiang University Hangzhou 310027 China

A spectrum method is used to simulate the time-developing free mixing layerwith cross shear which is introduced in different stages. The results show that the properties of flow are nearly the same for situations whether the cross shear is introduced in theinitial time or in early stage. If cross shear is introduced in the stage that the roll-up ofmixing layer occurs, the turbulent intensities of now will increase and mixture of now willbe enhanced.

关键词： free flow mixing layers (fluids) shear flow cross shear numerical simulation properties of flow

Thermo-responsive stick-slip behavior of advancing water contact angle on the surfaces of poly(N-isopropylacrylamide)-grafted polypropylene membranes

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Science china Chemistry 2010年第1期53卷 183-189,289页

作者： WAN LingShu,MENG XiangLin,YANG YunFeng,TIAN Jing & XU ZhiKang Key Laboratory of Macromolecular Synthesis and Functionalization,Ministry of Education department of Polymer Science and engineering,zhejiang university,hangzhou 310027,china Key Laboratory of Macromolecular Synthesis and Functionalization Ministry of Education department of Polymer Science and engineering Zhejiang University Hangzhou China

Wettability of a solid surface is highly important to its practical application,especially for the surface that shows thermoresponsive *** this paper,we describe a thermo-responsive stick-slip behavior of water droplets on the surfaces of poly(N-isopropylacrylamide)(PNIPAM)-grafted polypropylene *** emission scanning electron microscope(FESEM) images elucidate that the morphology of PNIPAM-grafted membrane surface is thermo-responsive,i.e.,the surface becomes rougher above the lower critical solution temperature(LCST) of *** the surface of nascent polypropylene membranes,the water droplet shows a smooth motion resulting in advancing and receding water contact angles of 111° and ～65°,*** the PNIPAM-grafted membrane surfaces,the water droplet shows a stick-slip pattern above the LCST,whereas it advances smoothly below the *** phenomenon is reproducible and can be ascribed to the energy barriers enhanced by the shrink of PNIPAM chains above the *** also find that the slip contact angle decreases from 102° to 92° after several stick-slip *** decrease is attributed to the water adsorption on the grafted PNIPAM layer,which is confirmed by the continuous decrease of the receding water contact angle.

关键词： stick-slip behavior water contact angle thermo-responsive surface poly(N-isopropylacrylamide) polypropylene membrane

Development of SOM combustion model for Reynolds-averaged and large-eddy simulation of turbulent combustion and its validation by DNS

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Science china(Technological Sciences) 2008年第8期51卷 1073-1086页

作者： ZHOU LiXing department of engineering mechanics, Tsinghua university, Beijing 100084, china department of engineering mechanics Tsinghua University Beijing China

The derivation and closure methods of the second-order moment (SOM) combus- tion model are proposed. The application of this model to Reynolds averaged (RANS) and large-eddy simulation (LES) of turbulent swirling diffusion combustion, jet diffusion combustion, and bluff-body stabilized premixed combustion is sum- marized. It is indicated that the SOM model is much better than the eddy-beak-up (EBU) and presumed PDF models widely used in commercial software and engi- neering. The SOM modeling results are close to those obtained using the most accurate but much more complex PDF equation model. Moreover, it can save much more computation time than the PDF equation model. Finally, the SOM model is validated by the direct numerical simulation (DNS) of turbulent reacting channel flows.

关键词： turbulent combustion second-order moment model Reynolds averaged simulation large-eddy simulation

Physically-based approach to analyze rainfall-triggered landslide using hydraulic gradient as slide direction

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Journal of zhejiang university-Science A(Applied Physics & engineering) 2012年第12期13卷 943-957页

作者： Qi-hua RAN1,Dan-yang SU1,Qun QIAN1,Xu-dong FU2,Guang-qian WANG1,2,Zhi-guo HE3 (1department of Hydraulic engineering,zhejiang university,hangzhou 310058,china) (2State Key Laboratory of Hydroscience and engineering,Tsinghua university,Beijing 100084,china) (3department of Ocean Science and engineering,zhejiang university,hangzhou 310058,china) department of Hydraulic engineering Zhejiang University Hangzhou China State Key Laboratory of Hydroscience and engineering Tsinghua University Beijing China department of Ocean Science and engineering Zhejiang University Hangzhou China

An infinite slope stability numerical model driven by the comprehensive physically-based integrated hydrology model(InHM) is *** this approach,the failure plane is assumed to be parallel to the hydraulic gradient instead of the slope *** method helps with irregularities in complex terrain since depressions and flat areas are allowed in the *** present model has been tested for two synthetic single slopes and a small catchment in the Mettman Ridge study area in Oregon,United States,to estimate the shallow landslide *** results show that the present approach can reduce the simulation error of hydrological factors caused by the rolling topography and depressions,and is capable of estimating spatial-temporal variations for landslide susceptibilities at simple slopes as well as at catchment scale,providing a valuable tool for the prediction of shallow landslides.

关键词： Shallow landslide Infinite slope stability model Hydraulic gradient Physically-based hydrology model Integrated hydrology model(InHM)

Effects of Ca substitution and surface treatment on electrochemical performances of Ml_(1.0-x) Ca_xNi_(4.0) Co_(0.6) Al_(0.4) hydrogen storage alloy electrodes

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中国有色金属学会会刊：英文版 1999年第3期9卷 487-492页

作者： Chen Weixiang(陈卫祥) 1, Qi Jianqin(祁建琴) 1, Chen Changpin(陈长聘) 2 1. department of Physics 2. department of Materials Science and engineering, zhejiang university, hangzhou 310027, P. R. china 浙江大学物理系浙江杭州浙江大学材料科学与工程系浙江杭州

The influences of Ca substitution for Ml and surface treatment on electrochemical performances of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 hydrogen storage alloy electrode were investigated. Ca substitution with x 0.2 could decrease the capacity. It was also found that Ca substitution deteriorates the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode. In order to improve these properties of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 alloy electrode, the alloy was treated in 6 mol/L KOH+0.02 mol/L KBH 4 solution. The results showed that the surface treatment improves the electrochemical performances such as the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode. :The influences of Ca substitution for Ml and surface treatment on electrochemical performances of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 hydrogen storage alloy electrode were investigated. Ca substitution with x 0.2 could decrease the capacity. It was also found that Ca substitution deteriorates the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode. In order to improve these properties of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 alloy electrode, the alloy was treated in 6 mol/L KOH+0.02 mol/L KBH 4 solution. The results showed that the surface treatment improves the electrochemical performances such as the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode.

关键词： hydrogen storage alloy electrode Ca substitution surface modification