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Numerical research on the 3D fiber orientation distribution in arbitrary planar flows

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Progress in Natural science:Materials International 2007年第11期17卷 1357-1362页

作者： Zhou Kun1 and Lin Jianzhong1,2.1. State Key Laboratory of Fluid Power Transmission and Control, Zhejiang university, hangzhou 31002., {2. 2. {2. Jiliang university, hangzhou 310018, {2.) State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China china Jiliang university Hangzhou 310018 China

The fiber orientation distribution in a fiber suspension flow was investigated by a finite difference scheme in spherical coordinates. The diffusivity was transformed between Cartesian and spherical coordinates through tensor analysis to obtain efficiency. It is found that under simple shear flow condition the diffusivity in the azimuthal direction, Dr, has greater effect on the orientation distribution than that in the colatitude direction, Drθθ.

关键词： fiber suspension flow orientation distribution diffusivity

FUNCTIONAL MODULUS OF CONTINUITY FOR BROWNIAN MOTION IN HLDER NORM

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Chinese Annals of Mathematics,Series B 2001年第2期22卷 223-232页

作者： WEI QICAI school of Economics, Zhejiang university, {2. 31002., china. school of Economics Zhejiang University Hangzhou 310028 China

The author establishes a large deviation for k-dimensional Brownian motion B in stronger topology, by which the functional modulus of continuity for B in Holder norm can be obtained.

关键词： Large deviations Functional modulus of continuity k-dimensional Brownian motion Holder norm

Constrained Bézier curves' best multi-degree reduction in the L2.norm

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Progress in Natural science:Materials International 2005年第9期15卷 843-850页

作者： ZHANG Renjiang 1,2.** and WANG Guojin1(1. Institute of Computer Images and Graphics, Zhejiang university, hangzhou 31002., {2. 2. {2. Institute of Metrology, Zhejiang, hangzhou 310034, {2.) Institute of Computer Images and Graphics Zhejiang University Hangzhou 310027 China State Key Laboratory of CAD and CG Zhejiang University Hangzhou 310027 China china Institute of Metrology Hangzhou 310034 China

In computer aided geometric design, the degree reduction of the parameter curve is a key technique in data exchange and data compression. The various existing methods of degree reduction cannot decide whether the degree reduction curve satisfying the given tolerance exists beforehand, cannot give approximation of the best multi-degree reduction, or cannot provide explicit expression and error formula of the degree reduction curve. In this paper, we propose an entirely new method, which can hurdle the above flaws completely. For a given Bézier curve of degree n, we can easily decide whether a Bézier reduction curve of degree m exists, which has equal derivatives with the given curve up to （r-1）-th and （s-1）-th orders （r,s≤m） respectively at the endpoints, so the approximating error is less than the given tolerance ε in the L2.norm. If the curve exists, the explicit expression can be given.

关键词： computer aided design Bézier curve degree reduction L2.norm tolerance.

Equilibrium equations for nonlinear buckling analysis of drill-strings in 3D curved well-bores

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science china(Technological sciences) 2009年第3期52卷 590-595页

作者： TAN MeiLan1 & GAN LiFei2.1 Faculty of science, Jiangsu university, Zhenjiang 2.2.13, {2. 2.94973 Unit in hangzhou of Zhejiang Province, hangzhou 31002., {2. Faculty of science Jiangsu University Jiangsu China 94973 Unit in hangzhou of Zhejiang Province Hangzhou China

With the development of drilling technology, the oil/gas well has evolved from its early vertical straight form to the inclined, horizontal, plane curved, or even 3D curved well-bore. Understanding of the buck- ling behavior of a drill-string in a well-bore is crucial for the success of a drilling operation. Therefore, equilibrium equations for analyzing the buckling behavior of a drill-string in a 3D curved well-bore are required. Based on Love’s equilibrium equations for a curved and twisted rod in space, a set of equi- librium equations for the nonlinear buckling analysis of a drill-string in a 3D curved well-bore are de- rived by introducing a radial constraint of the well-bore. The proposed formulae can account for the well curvature and tortuosity. Thus, it can be used to analyze the buckling behaviors of a drill-string constrained in a well-bore and subjected to axial compression, torsion at its upper end, and gravity simultaneously. It is worth noting that the existing equations in the literature for a drill-string in a straight and plane curved well-bore with a constant curvature are a special case of the proposed model. Thus, the present model can provide a theoretical basis for the nonlinear buckling analysis of a drill-string constrained in a 3D curved well-bore.

关键词： nonlinear buckling tortuosity constraint equilibrium equations drill-strings 3D curved well-bores

Online uniform machine covering with the known largest size

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Progress in Natural science:Materials International 2007年第11期17卷 1271-1278页

作者： Cao Shunjuan1,2.and Tan Zhiyi1,3(1. Department of Mathematics, Zhejiang university, hangzhou 31002., {2. 2. Department of Mathematics, Zhejiang Forestry university, hangzhou 311300, {2. 3. State Key Laboratory of CAD & CG, Zhejiang university, hangzhou 31002., {2.) Department of Mathematics Zhejiang University Hangzhou 310027 China Department of Mathematics Zhejiang Forestry University Hangzhou 311300 China State Key Laboratory of CAD and CG Zhejiang University Hangzhou 310027 China

This paper investigates the semi-online scheduling problem with the known largest size on two uniform machines. The objective is to maximize the minimum machine completion time. Both lower bounds and algorithms are given. Algorithms are optimal for the majority values of s≥1, where s is the speed ratio of the two machines. The largest gap between the competitive ratio and the lower bound is about 0.064. Moreover, the overall competitive ratio 2.matches the overall lower bound.

关键词： scheduling and covering uniform machine design and analysis of algorithm online competitive ratio

Numerical simulation of the efficiency of mixing in heterogeneous microchannels with patterned surface potentials

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Progress in Natural science:Materials International 2006年第12期16卷 1322-1328页

作者： ZHANG Kai~1, LIN Jianzhong~ 1,2.** and LI Huijun~1(1. State Key Laboratory of Fluid Power Transmission and Control, Zhejiang university, hangzhou 31002., {2. 2. {2. Jiliang university, hangzhou 310018, {2.) State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China china Jiliang university Hangzhou 310018 China

The mixing of samples in heterogeneous microchannels with a periodically stepwise surface potential was analyzed numerically using the control volume method. The equations describing the wall potential and external potential were solved first to get the distribution of wall potential and external potential, respectively, then the momentum equation was solved to get the developed flow field. Finally, the mass transport equation was solved to get the concentration field. The simulation results show that the distribution of samples at the inlet of the microchannel determines its theoretical value of concentration, therefore, the pattern of the distribution of samples at the inlet and its corresponding velocity can be changed to get the desirable concentration of solute. The heterogeneous wall potential almost has no effect on the mixing of samples in two-inlet microfluidic devices. For three-inlet microfluidic devices, the comprehensive ability of transportation and mixing has an optimization when the ratio of periodic length of wall potential to the height of the microchannel is about 4.88. The above conclusions are helpful to the optimization of the design of microfluidic devices.

关键词： microchannel mixing efficiency electroosmosis numerical simulation.

Interaction mechanisms of organic contaminants with burned straw ash charcoal

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Journal of Environmental sciences 2010年第10期22卷 1586-1594页

作者： Wenhai Huang,Baoliang Chen Department of Environmental science,Zhejiang university,{2. 31002.,china Department of Environmental science Zhejiang University Hangzhou 310028 China

Black carbons （e.g., charcoal） have a great impact on the transport of organic contaminants in soil and water because of its strong affinity and ubiquity in the environment. To further elucidate their interaction mechanism, sorption of polar （p-nitrotoluene, m-dinitrobenzene and nitrobenzene） and nonpolar （naphthalene） aromatic contaminants to burned straw ash charcoal under different de-ashed treatments were investigated. The sorption isotherms fitted well with Freundlich equation, and the Freundlich N values were all around 0.31-0.38, being independent of the sorbate properties and sorbent types. After sequential removal of ashes by acid treatments （HCl and HCl-HF）, both adsorption and partition were enhanced due to the enrichment of charcoal component. The separated contribution of adsorption and partition to total sorption were quantified. The effective carbon content in ash charcoal functioned as adsorption sites, partition phases, and hybrid regions with adsorption and partition were conceptualized and calculated. The hybrid regions increased obviously after de-ashed treatment. The linear relationships of Freundlich N values with the charring-temperature of charcoal or biochar （the charred byproduct in biomass pyrolysis） were observed based on the current study and the cited publications which included 15 different temperatures （100-850℃）, 10 kinds of precursors of charcoal/biochar, and 10 organic sorbates.

关键词： ash charcoal organic pollutant adsorption partition effective carbon

Electro-mechanical response of functionally graded beams with imperfectly integrated surface piezoelectric layers

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science china(Physics,Mechanics & Astronomy) 2006年第5期49卷 513-525页

作者： YAN Wei1 & CHEN Weiqiu1,2.1. Department of Civil Engineering, Zhejiang university, hangzhou 31002., {2. 2. State Key Lab of CAD & CG, Zhejiang university, hangzhou 31002., {2. Department of Civil Engineering Zhejiang University Hangzhou China State Key Lab of CAD & CG Zhejiang University Hangzhou China

The time-dependent behavior of a simply-supported functionally graded beam bonded with piezoelectric sensors and actuators is studied using the state-space method. The creep behavior of bonding adhesives between piezoelectric layers and beam is characterized by a Kelvin-Voigt viscoelastic model, which is practical in a high temperature circumstance. Both the host elastic functionally graded beam and the piezoelectric layers are orthotropic and in a state of plane stress, with the former being inhomogeneous along the thickness direction. A laminate model is employed to approximate the host beam. Moreover, the coupling effect between the elastic deformation and electric field in piezoelectric layers is considered. Results indicate that the viscoelastic property of interfacial adhesives has a significant effect on the function of bonded actuators and sensors with time elapsing.

关键词： functionally graded beam piezoelectric layers Kelvin-Voigt model state-space method

Notifiable infectious disease surveillance with data collected by search engine

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Journal of Zhejiang university-science C(Computers and Electronics) 2010年第4期11卷 241-248页

作者： Xi-chuan ZHOU1,Hai-bin SHEN2.(1Department of Information science and Electronic Engineering,Zhejiang university,{2. 31002.,china) (2.4} of Electrical Engineering,Zhejiang university,{2. 31002.,china) Department of Information science and Electronic Engineering Zhejiang University Hangzhou China school of Electrical Engineering Zhejiang University Hangzhou China

Notifiable infectious diseases are a major public health concern in china,causing about five million illnesses and twelve thousand deaths every *** detection of disease activity,when followed by a rapid response,can reduce both social and medical impact of the *** aim to improve early detection by monitoring health-seeking behavior and disease-related news over the ***,we counted unique search queries submitted to the Baidu search engine in 2.08 that contained disease-related search *** we counted the news articles aggregated by Baidu's robot programs that contained disease-related *** found that the search frequency data and the news count data both have distinct temporal association with disease *** adopted a linear model and used searches and news with 1–2.0-day lead time as explanatory variables to predict the number of infections and deaths attributable to four notifiable infectious diseases,i.e.,scarlet fever,dysentery,AIDS,and *** the search frequency data and news count data,our approach can quantitatively estimate up-to-date epidemic trends 10–40 days ahead of the release of Chinese Centers for Disease Control and Prevention(Chinese CDC)*** approach may provide an additional tool for notifiable infectious disease surveillance.

关键词： Notifiable infectious diseases Disease surveillance Search engine