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Back-scattering from rough sea surface with foams

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Acta Oceanologica Sinica 1993年第4期12卷 563-572页

作者： Jin Yaqiu, Huang Xingzhong and Yin Jieyi department of Electronic engineering, Fudan {2., shanghai 2.0433, china department of Electronic Science, china East Normal {2., shanghai 2.0062. china Dept of Electronic engineering Fudan University Shanghai 200433 China China

By using iterative method to solve the vector radiative transfer equation of discrete scatterers with randomly rough under-boundary, the back-scattering coefficient is derived, and is applied to the two-scale model of sea surface with foam scatterers driven by strong wind. By employing the modified probability density function of Cox and Munk's, and Pierson's sea spectrum, numerical results of polarized back-scatter ing are calculated. The functional dependence on wind speed and direction, observation angle, polarization and other parameters are discussed, and theoretical results are favorably matched with experimental data.

关键词： Radiative transfer two-scale randomly rough surface back-scattering wind

A Heuristic Algorithm for the Two-Machine Flowshop Group Scheduling Problem

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Journal of Systems engineering and Electronics 2002年第4期13卷 8-16页

作者： Wang Xiuli & Wu Tihua department of Automation, shanghai Jiaotong {2., shanghai 2.0030, P.R. china department of Automation Shanghai Jiaotong University Shanghai 200030 P. R. China

This paper presents the two-machine flowshop group scheduling problem with the optimal objective of maximum lateness. A dominance rule within group and a dominance rule between groups are established. These dominance rules along with a previously established dominance rule are used to develop a heuristic algorithm. Experimental results are given and analyzed.

关键词： Group scheduling Flowshop Heuristic algorithm.

同方期刊数据库

OPTIMAL CONTROL APPLIED IN AUTOMATIC CLUTCH ENGAGEMENTS OF VEHICLES

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Chinese Journal of Mechanical engineering 2004年第2期17卷 280-283页

作者： Sun Chengshun Zhang Jianwu School of Mechanical and Power engineering,shanghai Jiaotong {2.,shanghai 2.0030, china School of Mechanical and Power engineering Shanghai Jiaotong University Shanghai 200030 China department of Science and Technology Studies University College London WC1E 6BT UK

Start-up working condition is the key to the research of optimal engagementof automatic clutch for AMT. In order to guarantee an ideal dynamic performance of the clutchengagement, an optimal controller is designed by considering throttle angle, engine speed, gearratio, vehicle acceleration and road condition. The minimum value principle is also introduced toachieve an optimal dynamic performance of the nonlinear system compromised in friction plate wearand vehicle drive quality. The optimal trajectory of the clutch engagement can be described in theform of explicit and analytical expressions and characterized by the deterministic and accuratecontrol strategy in stead of indeterministic and soft control techniques which need thousands ofexperiments. For validation of the controller, test work is carried out for the automated clutchengagements in a commercial car with an traditional mechanical transmission, a hydraulic actuator, agroup of sensors and a portable computer system. It is shown through experiments that dynamicbehaviors of the clutch engagement operated by the optimal control are more effective and efficientthan those by fuzzy control.

关键词： Automatic clutch Optimal control Nonlinear system dynamics

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 2., 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

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 {2., Beijing 100084, china 2. School of civil engineering, Tianjin {2., Tianjin 300072. 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 1.10 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

Puncturing Period on the Performance of Punctured Turbo Codes

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Wuhan university Journal of Natural Sciences 2002年第3期7卷 319-322页

作者： Xu Heng\|ping, Pan Sheng, Zhao Xun, Rong Meng\|tian department of Electronic engineering, {2. Jiaotong university, {2. 2.0030, {2., china shanghai Jiaotong university Department of Electronic Engineering Shanghai Shanghai China (GRID:grid.16821.3c) (ISNI:***)

Puncturing is the predominant strategy to construct high code rate turbo codes. Puncturing period is a crucial parameter influencing the performance of punctured turbo codes (PTC). Here we developed a new puncturing scheme of turbo codes, with which the puncturing period on the performance of PTC is studied. Consequently, suggestions on selecting the puncturing period are proposed.

关键词： Key words puncturing period puncturing table AWGN turbo codes

Elastohydrodynamic Lubrication Studies on Effects of Crowning Value in Roller Bearings

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Journal of shanghai university(English Edition) 2001年第1期5卷 76-81页

作者： CHEN Xiao yang, SHEN Xue jin School of Electromechanical engineering and Automation, shanghai university,{2., china XU Wen, MA Jia ju department of Mechanical engineering, Zhejiang university, Hangzhou 31002., china School of Electromechanical engineering and Automation Shanghai University Shanghai China department of Mechanical engineering Zhejiang University Hangzhou China

The purpose of this paper is to present a comparison of numerical calculations and experiment results of optical interferometry in finite line contact for the elastohydrodynamic lubrication(EHL) problem of Lundberg's profiled cylindrical roller under the conditions of flooded state, moderate load and material parameter. It shows clearly the effects of crowning value on the variations of oil film shape and thickness. The agreement between numerical analysis and experiment results is very good. The results indicate there must be an optimum crowning value that will induce the thickest and most even oil film in EHL state for a given working condition, and this value is larger than the design value in dry contact state for the same working conditions.

关键词： roller bearings crowning value elastohydrodynamic lubrication

FUZZY KNOWLEDGE ACQUIREMENT IN GATE DESIGN

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Chinese Journal of Mechanical engineering 2000年第1期13卷 70-75,80页

作者： Lou Zhouliang Zhang Yongqing (department of Plastic Forming engineering, {2. Jiaotong university) 上海交通大学上海

In order to reduce time and cost in engineering design, such as gate design, integral field knowledge must be obtained efficiently. After studying ID3 and its improved methods, a new algorithm(Fuzzy ID3 ) and its main concepts are presented to overcome some disadvantage in classical ID3 algorithms. In its application of gate design, fuzzy knowledge gotten by the new algorithm is more efficient than the knowledge by other ID3 algorithms, the set of fuzzy knowledge is much smaller than that of knowledge by classical ID3 algorithms. On the other hand, fuzzy knowledge represents field data more naturally to the way of bar thinking and more robust in tolerating imprecise, conflicting and missing information

关键词： Gate design Fuzzy ID3 Knowledge acquirement Expert system

AN EXACT SYMPLECTIC SOLUTION FOR THE DYNAMIC ANALYSIS OF SHEAR DEFORMABLE ANTISYMMETRIC ANGLE-PLY LAMINATED PLATES

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Acta Mechanica Solida Sinica 1996年第3期9卷 263-273页

作者： Zou Guiping (department of engineering Mechanics,Tongji {2.,shanghai 2.0092. TONGJI UNIV DEPT MECH ENGN SHANGHAI 200092 PEOPLES R CHINA

From the mixed variational principle, by the selection of the state variables and its dual variables, the Hamiltonian canonical equation for the dynamic analysis of shear deformable antisymmetric angle-ply laminated plates is derived, leading to the mathematical frame of symplectic geometry and algorithms, and the exact solution for the arbitrary boundary conditions is also derived by the adjoint orthonormalized symplectic expansion method. Numerical results are presented with the emphasis on the effects of length/thickness ratio, arbitrary boundary conditions, degrees of anisotropy, number of layers, ply-angles and the corrected coefficients of transverse shear.

关键词： Hamilton canonical equation symplectic free vibration analysis antisymmetric angle-ply laminated plates