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Tracheal compliance and limit flow rate changes in a murine model of asthma

science china(Life sciences) 2008年第10期51卷 922-931页

作者： TENG ZhongZhao1, WANG YiQin2, LI FuFeng2, YAN HaiXia2 & LIU ZhaoRong3 1 department of Mathematical sciences, Worcester Polytechnic Institute, Worcester, MA, 01609, USA 2 Syndrome Laboratory of TCM, shanghai university of Traditional Chinese Medicine, shanghai 201203, china 3 department of mechanics and engineering science, fudan university, shanghai 200433, china department of Mathematical sciences Worcester Polytechnic Institute Worcester USA Syndrome Laboratory of TCM Shanghai University of Traditional Chinese Medicine Shanghai China department of mechanics and engineering science Fudan University Shanghai China

Trachea is the unique passage for air to flow in and out. Its tone is of importance for the respiration system. However, investigation on how tracheal tone changes due to asthma is limited. Aiming at studying how the mechanical property changes due to asthma as well as the compliance and flow limitation, the following methods are adopted. Static and passive pressure-volume tests of rats' trachea of the asthmatic and control groups are carried out and a new type of tube law is formulated to fit the experimental data, based on which changes of compliance and limit flow rate are investigated. In order to give explanation to such changes, histological examinations with tracheal soft tissues are made. The results show that compliance, limit flow rate and material constants included in the tube law largely depend on the longitudinal stretching ratio. Compared with the control group, the tracheal compliance of asthmatic animals decreases significantly, which results in an increased limit flow rate. Histological studies indicate that asthma can lead to hyperplasia/hypertrophy of smooth muscle cells, and increase elastin and collagen fibres in the muscular membrane. Though decreasing compliance increases sta- bility, during the onset of asthma, limit flow rate is much smaller due to the lower transmural pressure. Asthma leads to a stiffer trachea and the obtained results reveal some aspects relevant to asthma-induced tracheal remodelling.

关键词： trachea asthma collapse tube law compliance limit flow rate remodelling

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卫星振动实验中台面加速度控制与过实验研究

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力学季刊 2009年第3期30卷 427-431页

作者：王亚波宋汉文陈昌亚齐晓军复旦大学力学与工程科学系上海200433 同济大学航空航天与力学学院上海200092 上海卫星工程研究所上海200240

针对航天飞行器振动台环境实验中的"过实验"问题与振动台控制方式展开研究。本文以被试结构和振动台为统一研究对象进行组合系统动力学建模,详细导出了"真实环境"、"台面加速度控制"和"界面力控制"等三种模式下的台面加速度、界面力、... 详细信息

针对航天飞行器振动台环境实验中的"过实验"问题与振动台控制方式展开研究。本文以被试结构和振动台为统一研究对象进行组合系统动力学建模,详细导出了"真实环境"、"台面加速度控制"和"界面力控制"等三种模式下的台面加速度、界面力、结构测点加速度响应等表达公式,并讨论了加速度控制和力控制下各自形成过实验的原因和频率位置,定义并解释了"双控"模式及其对过实验现象的补偿机理。借助离散算例仿真计算,解释了文中提出的各种概念及其数值效果。

关键词：飞行器振动台实验过实验力限振动双控

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CDS Simulation and Pattern Formation of Phase Separation

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Communications in Nonlinear science and Numerical Simulation 1998年第4期3卷 233-236页

作者： Zhanaji LIU Men CHENG Jiong RUAN and Shouji CHENG (department of mechanics and engineering science, fudan university, shanghai 200433,china)(department of Mathematics, fudan university, shanghai 200433, china) Dept. of mechanics and Eng. science Fudan University Shanghai 200433 China department of Mathematics Fudan University Shanghai 200433 China

Several properties of the generation and evolution of phase separating patterns for binary material studied by CDS model are proposed. The main conclusions are (1) for alloys spinodal decomposition, the conceptions of "macro-pattern" and "micropattern" are posed by "black-and- white graph" and "gray-scale graph" *** find that though the four forms of map f that represent the self-evolution of order parameter in a cell(lattice) are similar to each other in "macro-pattern" , there are evident differences in their micro-pattern, e.g., some different fine netted structures in the blackdomain and the white domain are found by the micro-pattern, so that distinct mechanical and physical behaviors shall be obtained. (2) If the two constitutions of block copolymers are not symmetric (i.e. r ≠ 0.5), a pattern called "grain-strip cross pattern"is discovered,in the 0.43 < r < 0.45.

关键词： lattice gas automata CDS phase separation Pattern formation

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NUMERICAL SIMULATION OF TWO-PHASE GRAVITY CURRENTS OVER A POROUS SUBSTRATE

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Journal of Hydrodynamics 2003年第5期15卷 81-90页

作者： Zhou Liang , Hu Yue, Zhang Hui sheng department of mechanics and engineering science, fudan university, shanghai 200433, china, Dept. of Mech. and Eng. Sci. Fudan Univ. Shanghai 200433 China

Based on shallow-water approximations the governing equations for twodimensional two-phase gravity currents over a porous substrate and some appropriate boundaryconditions were introduced. With on characteristic interpolations the numerical boundary conditionswere introduced and a series of exact solutions were constructed. Numerical a-nalysis were made byusing the two-step Lax scheme, second-order TVD scheme, third-order ENO scheme and fifth-order WE NOscheme combined with second- and third-order TVD-Runge-Kutta method is given. It is found that forpractice applications the second-order TVD scheme combined with the second-order TVD- Runge- Kuttamethod is an economical and suitable choice.

关键词： two-phase gravity currents porous substrate numerical simulation

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VISCOSITY EFFECTS ON THE BEHAVIOR OF A RISING BUBBLE

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Journal of Hydrodynamics 2010年第1期22卷 81-89页

作者： WANG Han ZHANG Zhen-yu YANG Yong-ming ZHANG Hui-sheng department of mechanics and engineering science Fudan University Shanghai 200433 China department of Mathematics Shanghai University of Finance and Economics Shanghai 200433 China

In the incompressible fluid flow regime, without taking consideration of surface tension effects, the viscosity effects on the behavior of an initially spherical buoyancy-driven bubble rising in an infinite and initially stationary liquid are investigated numerically by the Volume Of Fluid （VOF） method. The ratio of the gas density to the liquid density is taken as 0.001, and the gas viscosity to the liquid viscosity is 0.01, which is close to the case of an air bubble rising in water. It is found by numerical experiments that there exist two critical Reynolds numbers Re1 and Re2 , which are in between 30 and 50 and in between 10 and 20, respectively. As Re 〉 Re1 the bubble will have the transition to toroidal form, and the toroidal bubble will break down into two toroidal bubbles. In this case viscosity will damp the development of the liquid jet and delay the formation of the toroidal bubble. As Re〈Re1 the transition will not happen. As Re2 〈 Re 〈 Re1, the bubble will split from its rim into a toroidal bubble and a spherical cap-like bubble, and as Re〈Re2 the splitting will not occur and the bubble can finally reach a stationary shape. With the decrease of the Reynolds number, the stationary shape changes from spherical-cap bubble with skirt to dimpled peach-like bubble. Before the bubble reaches its stationary shape the vortex structure in the flow field varies with time. The vortex structure corresponding to bubble stationary shape varies with the Reynolds number. It is also found that there exists another critical Reynolds number Re^＊ which is in between Re1 and Re2 , and as Re 〈 Re^＊, after the bubble rises in an accelerating manner for a moment, it will rise with an almost constant speed, and the speed increases with increasing Reynolds number. As Re 〉 Re^＊, it will not rise with a constant speed. The mechanism of the above phenomena has been analyzed theoretically and numerically.

关键词： rising bubble viscosity effects buoyancy force Volume Of Fluid (VOF) method

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Dispersion of Soluble Matters in Newton-dipolar Stratified Fluid and Effects of Peripheral Layer

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Communications in Nonlinear science and Numerical Simulation 1998年第4期3卷 236-241页

作者： Zhangji LU, Shousheng DONG, Yu SHEN and Guangping ZHENG (department of mechanics and engineering science, fudan university, shanghai 200433,china)(department of Physics, East china Normal university, shanghai 200062, china) Dept. of mechanics and Eng. science Fudan University Shanghai 200433 China department of Physics East China Normal University Shanghai 200062 China

In the paper, the dispersion law and the concentration distributions of soluble matters in Newton-dipolar fluids flowing through a circular tube have been investigated. Main results are: (1) for the dependence of M on A (or H), the completely opposite trends are obtained in the cases with and without the peripheral layer. (2) effects of δ on　M have the minimum values near 8=0.85-0.9. (3) various models such as couple stress,micropolar, dipolar, Newton-newtonian, Newton-couple stress and Newton-micropolar　model etc. are all special cases of Newton-dipolar fluid (where Mz=0). WhenMz≠ 0,however, there are evident differences between the Newton-dipolar fluid and the Newtoncouple stress fluid, the Newton-micropolar fluid.

关键词： dipolar fluid dispersion effects of a peripheral layer tube flow of complex fluid

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An optimal adaptive filtering algorithm with a polynomial prediction model

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science china(Information sciences) 2011年第1期54卷 153-162页

作者： TAN JiaJia & ZHANG JianQiu department of Electronic engineering,fudan university,shanghai 200433,china department of Electronic engineering Fudan University Shanghai China

A new approach to the optimal adaptive filtering is proposed in this *** this approach,a polynomial prediction model is used to describe the time-variant/invariant impulse response coeffcients of an identified *** the polynomial prediction model is viewed as the state equations of the identified impulse response coeffcients and the relationships between the inputs and outputs of the system are regarded as the measurements of the states,our adaptive filtering can be achieved in the framework of the Kalman filter. It is understood that Kalman filter is optimal in the sense of the MAP(maximum a posteriori),ML(most likelihood)and MMSE(minimum mean square error)under the linear and Gaussian white noise *** a result,our algorithm is also optimal in the statistical senses as Kalman filter does,provided that the impulse response coeffcients can be modeled by a *** only do the analytical results of the algorithm but also the simulation results show that our algorithm outperforms the traditional known algorithms.

关键词： adaptive filters polynomial prediction model impulse response coeffcients process equation Kalman filter optimal

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SIMULATION OF FLUID-SOLID INTERACTION ON WATER DITCHING OF AN AIRPLANE BY ALE METHOD

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Journal of Hydrodynamics 2011年第5期23卷 637-642页

作者： HUA Cheng FANG Chao CHENG Jin department of mechanics and engineering science Fudan University Shanghai 200433 China School of Mathematical sciences Fudan University Shanghai 200433 China

Ditching is considered as one of the important aspects of safety performances of airplanes. It is related primarily with the fluid-solid interaction, whose studies mainly depend on experiments at the present time. Numerical and analytical methods for fluid-solid interaction by using 3-D full scale airplane＇s model will reduce the dependence on the expensive model tests. Numerical studies can be used to estimate the safety of ditching and provide a reference for the crashworthiness design. This article proposes a 3-D dynamical structural model after the real shape of an airplane and an Arbitrary Lagrange-Euler （ALE） fluid-field model, to simulate the fluid-solid interactions caused by low speed ditching. The simulation is based on interaction computational methods, within LS-DYNA nonlinear finite-element code. The results of pressure distributions and accelerating time histories of the airplane＇s subfloor are discussed in the context of the safety of ditching, and the simulation results and the analytical methods are verified.

关键词： ditching fluid structure interaction Arbitrary Lagrange-Euler (ALE) finite element method

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Dynamics of Primary Events in the Photocycle of Excited Bacteriorhodopsin

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Acta Biochimica et Biophysica Sinica 2004年第11期36卷 724-728页

作者： Jun-Jun LU, Ming MING, Yi YANG, Jia WU, Bo LI, Jian-Dong DING, Qing-Guo LI, and Shi-Xiong QIANdepartment of Physics, fudan university, shanghai 200433, china department of Macromolecular science, Key Laboratory of Molecular engineering of Polymers, fudan university, shanghai 200433, china department of Physiology and Biophysics, School of Life sciences, fudan university, shanghai 200433, china department of Physics Fudan UniversityShanghai 200433 China department of Macromolecular science Key Laboratory of Molecular Engineering of Polymers Fudan UniversityShanghai 200433 China department of Physiology and Biophysics School of Life Sciences Fudan UniversityShanghai 200433 China

Transient dynamic behavior of the excited bacteriorhodopsin (BR), which was isolated from the strain H. salinarum, was studied at excitation wavelength from 585 to 639 nm. With the one-color femtosecond (fs) pump-probe technique, we revealed the primary events in BR's photocycle that took place in an ultrafast time scale. From the analysis of the decay components of the dynamical traces, it was evident that the isomerization of the retinal

关键词： bacteriorhodopsin transient dynamics primary events femtosecond laser pump-probe technique

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Dynamic Monte Carlo simulation of chain growth polymerization and its concentration effect

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science china Chemistry 2005年第5期48卷 459-465页

作者： Lü Wenqi & DING Jiandong Key Laboratory of Molecular engineering of Polymers, department of Macromolecular science, fudan university, shanghai 200433, china Key Laboratory of Molecular engineering of Polymers Department of Macromolecular Science Fudan University Shanghai China

Free radical polymerization and living ion polymerization have been simulated via the dynamic Monte Carlo method with the bond-fluctuation model in this paper. The polymeriza-tion-related parameters such as conversion of monomers, degree of polymerization, average molecular weight and its distribution are obtained by statistics. The simulation outputs are con-sistent with the corresponding theoretical predictions. The scaling relationships of the coil size versus chain length are also confirmed at different volume fractions. Furthermore, the effect of diffusion on polymerization is revealed preliminarily in our simulation. Hence the simulation ap-proach has been proven to be feasible to investigate polymerization reactions with the advan-tages that configuration and diffusion of polymer chains can be examined together with polym-erization kinetics.

关键词： living ion polymerization free radical polymerization concentration effect configuration Monte Carlo simulation.

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