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Differences between laminar convections through parallel plain planes with uniform wall temperature and heat flux in terms of process parameter

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Science China(Technological Sciences) 2010年第3期53卷 789-799页

作者： WANG LiangBi,LIN ZhiMin,WU Xiang&SONG KeWei school of mechatronic engineering,lanzhou jiaotong university,lanzhou 730070,China school of mechatronic engineering Lanzhou Jiaotong University Lanzhou China

Using the process parameter description,we analyzed the difference between the characteristics of laminar convections through parallel plain planes with uniform temperature and heat *** results show the following.(1)On the wall surface of the developing region,under uniform heat flux boundary condition,the heat flux normal to the wall surface is transported through a convection process although the velocity is zero;the velocity gradient contributes to this transport,but under uniform temperature boundary condition,the heat flux normal to the wall surface is transported through a difussion process.(2)Inside the flow of the developing region,whether under uniform temperature or heat flux boundary condition,the heat flux along the main flow direction and the heat flux normal to the wall surface are transported through a convection process,and the contributions of velocity and velocity gradient are dependent on the thermal boundary condition.(3)On the wall surface of the fully developed region,under uniform heat flux boundary condition,the heat flux normal to the wall surface is transported through a convection process;the velocity gradient contributes to this transport,but under uniform temperature boundary condition,the heat flux normal to the wall surface is transported through a diffusion process.(4)Inside the flow of the fully developed region,under uniform temperature boundary condition,the heat flux along the main flow direction and the heat flux normal to the wall surface are transported through a convection process,and the velocity and velocity gradient contribute to these transports;under uniform heat flux boundary condition,the heat flux along the main flow direction and the heat flux normal to the wall surface are transported through a convection ***,the transport of the heat flux along the main flow direction is a no-net convection process;the velocity gradient contributes to the transport of the heat flux only in the normal direction o

关键词： mechanism of convective heat transfer description of process parameter parallel plain planes uniform wall temperature uniform wall heat flux laminar flow

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Subinterval Decomposition-Based Interval Importance Analysis Method

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Computer Modeling in engineering & Sciences 2020年第9期124卷 985-1000页

作者： Wenxuan Wang Xiaoyi Wang school of mechatronic engineering Lanzhou Jiaotong UniversityLanzhou730070China

The importance analysis method represents a powerful tool for quantifying the impact of input uncertainty on the output *** an input variable is described by a specific interval rather than a certain probability distribution,the interval importance measure of input interval variable can be calculated by the traditional non-probabilistic importance analysis ***,the non-probabilistic importance analysis methods involve the Monte Carlo simulation(MCS)and the optimization-based methods,which both have high computational *** order to overcome this problem,this study proposes an interval important analytical method avoids the time-consuming optimization ***,the original performance function is decomposed into a combination of a series of one-dimensional ***,the interval of each variable is divided into several subintervals,and the response value of each one-dimensional subsystem at a specific input point is ***,the obtained responses are taken as specific values of the new input variable,and the interval importance is calculated by the approximated performance *** with the traditional non-probabilistic importance analysis method,the proposed method significantly reduces the computational cost caused by the MCS and optimization *** the proposed method,the number of function evaluations is equal to one plus the sum of the subintervals of all of the *** efficiency and accuracy of the proposed method are verified by five *** results show that the proposed method is not only efficient but also accurate.

关键词： Importance analysis method interval variable subinterval decomposition performance function MCS

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EFFECT OF SILICA NANOPARTICLES ON PROPERTIES OF WATERBORNE POLYURETHANES

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Chinese Journal of Polymer Science 2012年第6期30卷 845-852页

作者：冯利邦 Key Laboratory of Road Bridge and Underground engineering of Gansu Province Lanzhou Jiaotong University school of mechatronic engineering Lanzhou Jiaotong University

Waterborne polyurethane composites containing silica nanoparticles are synthesized successfully via the in situ polymerization. The structure, thermal stability, surface hardness, tensile strength, UV-Vis absorbance, dynamic mechanical properties and chemicals resistance of the resulting composites are investigated by FTIR, TEM, TGA, UV-Vis, DMA and chemicals soakage measurements. Results show that polyurethane molecules and silica nanoparticles are linked with covalent bonds. As a result, physical properties of polyurethane composites, such as thermal stability, surface hardness, weather and chemicals resistance are all improved when an appropriate concentration of silica nanoparticles are incorporated.

关键词： Nanosilica Waterborne Polyurethanes Property.

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A novel adaptive-impulsive synchronization of fractional-order chaotic systems

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Chinese Physics B 2015年第10期24卷 86-92页

作者： Leung Y.T.Andrew Li Xian-Feng Chu Yan-Dong Zhang Hui Department of Architecture and Civil engineering City University of Hong Kong school of Mathematics and Physics Lanzhou Jiaotong University school of mechatronic engineering Lanzhou Jiaotong University

A novel adaptive-impulsive scheme is proposed for synchronizing fractional-order chaotic systems without the necessity of knowing the attractors＇ bounds in priori. The nonlinear functions in these systems are supposed to satisfy local Lipschitz conditions but which are estimated with adaptive laws. The novelty is that the combination of adaptive control and impulsive control offers a control strategy gathering the advantages of both. In order to guarantee the convergence is no less than an expected exponential rate, a combined feedback strength design is created such that the symmetric axis can shift freely according to the updated transient feedback strength. All of the unknown Lipschitz constants are also updated exponentially in the meantime of achieving synchronization. Two different fractional-order chaotic systems are employed to demonstrate the effectiveness of the novel adaptive-impulsive control scheme.

关键词： adaptive-impulsive synchronization fractional order chaotic systems combined feedbackstrength

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Vibro-impact dynamics near a strong resonance point

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Acta Mechanica Sinica 2007年第3期23卷 329-341页

作者： Guanwei Luo Yanlong Zhang Jianhua Xie Jiangang Zhang school of mechatronic engineering Lanzhou Jiaotong UniversityLanzhou 730070 China Department of engineering Mechanics Southwest Jiaotong University Chengdu 610031 China school of Mathematics Physics and Software EngineeringLanzhou Jiaotong University Lanzhou 730070 China

Two typical vibratory systems with impact are considered, one of which is a two-degree-of-freedom vibratory system impacting an unconstrained rigid body, the other impacting a rigid amplitude stop. Such models play an important role in the studies of dynamics of mechanical systems with repeated impacts. Two-parameter bifurcations of fixed points in the vibro-impact systems, associated with 1 ： 4 strong resonance, are analyzed by using the center manifold and normal form method for maps. The single-impact periodic motion and Poincaré map of the vibro-impact systems are derived analytically. Stability and local bifurcations of a single-impact periodic motion are analyzed by using the Poincaré map. A center manifold theorem technique is applied to reduce the Poincaré map to a two-dimensional one, and the normal form map for 1：4 resonance is obtained. Local behavior of two vibro-impact systems, near the bifurcation points for 1：4 resonance, are studied. Near the bifurcation point for 1：4 strong resonance there exist a Neimark-Sacker bifurcation of period one single-impact motion and a tangent （fold） bifurcation of period 4 four-impact motion, etc. The results from simulation show some interesting features of dynamics of the vibro-impact systems： namely, the ＂heteroclinic＂ circle formed by coinciding stable and unstable separatrices of saddles, Tin, Ton and Tout type tangent （fold） bifurcations, quasi-periodic impact orbits associated with period four four-impact and period eight eight-impact motions, etc. Different routes of period 4 four-impact motion to chaos are obtained by numerical simulation, in which the vibro-impact systems exhibit very complicated quasiperiodic impact motions.

关键词： Vibration Impact Resonance Periodicmotion Bifurcation

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An Efficient Reliability-Based Optimization Method Utilizing High-Dimensional Model Representation and Weight-Point Estimation Method

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Computer Modeling in engineering & Sciences 2024年第5期139卷 1775-1796页

作者： Xiaoyi Wang Xinyue Chang Wenxuan Wang Zijie Qiao Feng Zhang school of mechatronic engineering Lanzhou Jiaotong UniversityLanzhou730070China school of Electronic and Information engineering Lanzhou Jiaotong UniversityLanzhou730070China school of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’anChina

The objective of reliability-based design optimization(RBDO)is to minimize the optimization objective while satisfying the corresponding reliability ***,the nested loop characteristic reduces the efficiency of RBDO algorithm,which hinders their application to high-dimensional engineering *** address these issues,this paper proposes an efficient decoupled RBDO method combining high dimensional model representation(HDMR)and the weight-point estimation method(WPEM).First,we decouple the RBDO model using HDMR and ***,Lagrange interpolation is used to approximate a univariate ***,based on the results of the first two steps,the original nested loop reliability optimization model is completely transformed into a deterministic design optimization model that can be solved by a series of mature constrained optimization methods without any additional *** numerical examples of a planar 10-bar structure and an aviation hydraulic piping system with 28 design variables are analyzed to illustrate the performance and practicability of the proposed method.

关键词： Reliability-based design optimization high-dimensional model decomposition point estimation method Lagrange interpolation aviation hydraulic piping system

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Hydrodynamic Properties of Fe3O4 Kerosene-Based Ferrofluids with Narrow Particle Size Distribution

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Chinese Physics Letters 2005年第11期22卷 2944-2946页

作者：张建辉许雪飞司明苏周又和薛德胜 Key laboratory for Magnetism and Magnetic Materials of Ministry of Education Lanzhou University Lanzhou 730000 school of mechatronic engineering Lanzhou Jiaotong University Lanzhou 730070

We investigate the hydrodynamic properties of Fe3O4 kerosene-based ferrofluids with narrow particle size distribution. The ferrofluids are synthesized by improving chemical coprecipitation technique. A narrow distribution of 8.6-10.8nm particle sizes is obtained from the magnetization curve with the free-form model based on the Bayesian inference theory. The fitting result is consistent with average particle size obtained from x-ray diffraction. With the increase of applied magnetic field and magnetic particle concentration, apparent viscosity of ferrofluids increases. At concentration 4.04%, the type of flow for the ferrofluid transforms from Newtonian to Bingham plastic fluid as the applied magnetic field increases.

关键词： RHEOLOGICAL PROPERTIES MAGNETIC FLUID FIELD

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Fractal structures in a generalized square map with exponential terms

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Chinese Physics B 2012年第3期21卷 15-21页

作者：李险峰褚衍东张惠 school of Mathematics Physics and Software EngineeringLanzhou Jiaotong University school of Mechanical engineering Lanzhou Jiaotong University

Fractal structures in a generalized squared map with exponential terms are expanded in this paper. We describe how complex behaviors can arise as the parameters change. The appearances of different kinds of fractal structures, in both the attractive and the divergent regions, and most interestingly, on small regular islands embedded in the chaotic region, are manifested to have a variety of extraordinary geometries in the parameter plane.

关键词： discrete map exponential term parameter plane Lyapunov fractal

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Case-based retrieval approach for machining fixture design utilizingontology

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Journal of Beijing Institute of Technology 2014年第3期23卷 352-357页

作者：高博阎艳丁洪生张发平王国新 school of Mechanical engineering Beijing Institute of Technology school of mechatronic engineering Lanzhou Jiaotong University

In order to develop an intelligent case-based reasoning （CBR） system to reuse fixture de- sign knowledge, ontology technology was integrated in CBR system by semantic annotation of fixture design case. Domain ontology of fixture design was constructed; concepts and relations were de- fined and represented. The 2-level similarity evaluation approach of domain ontology was presented. The concept similarity of cases was calculated as the first grade case retrieval. Numerical measure- ment was the second grade case retrieval, which adopted various methods to calculate different types of attribute values. The problem of similarity measurement of fixture design case was resolved. Pro- totype system based on the proposed method was illustrated and the retrieval approach was proved to be efficient.

关键词： fixture case ontology case-based reasoning similarity measurement

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Target surrounding control of second-order multi-agent systems with switching topology 36

Target surrounding control of second-order multi-agent syste...

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第36届中国控制会议

作者： Zonggang Li Si Chen Yajiang Du school of mechatronic engineering Lanzhou Jiaotong University

ISBN: (纸本)9781538629185

This paper considers the target surrounding control problem of second-order multi-agent systems with linear dynamics and switching *** our scheme,all agents finally converge to a circle around the target and then move along ***,a distributed protocol is given for each agent to estimate the position of static *** is shown that the estimation of each agent eventually converges to the target as the information topology contains a jointly spanning tree by employing the properties of row-stochastic matrix and non-negative ***,another distributed protocol is given for each agent moves around the target in a given *** important,all agents reach consensus on angular velocity and move uniformly distributed in this ***,a numerical example is *** results of simulation illustrate the validity of the proposed method.

关键词： Surrounding control Second-order Linear multi-agent systems Switching topology

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