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1.
分析非线性Newton-Leipnik系统的动力学性质,得出系统存在5个不稳定平衡态,导致系统形成复杂的双吸引子结构;通过数值计算得到系统随参数变化的倍周期分岔图,对其混沌态采用周期激励和线性反馈2种无反馈控制方法进行控制,当控制参数选择适当的范围时,将混沌运动控制为规则的周期运动;比较不同初始条件的上、下吸引子的控制... 相似文献
2.
分析具有四翼混沌吸引子系统(An系统)的动力学性质,得出系统存在9个不稳定平衡态,导致系统形成复杂的四翼吸引子结构.数值计算得出系统随参数变化的倍周期分岔图,通过单输入和多输入方式,采用线性反馈方法控制混沌态.结果表明:当控制参数选择适当的范围时,可以将混沌运动控制为规则的周期运动或稳定平衡态;不同初始条件的控制结果存... 相似文献
3.
对于承受轴向荷载的水平受荷桩，以往研究大多基于线弹性或弹塑性水平荷载传递模型。为提升轴横受荷桩的计算设计水平，采用轴向荷载传递法计算桩身轴力，考虑桩身轴力引起的P-Δ效应，基于双曲线型水平荷载传递模型考虑桩-土体系变形的非线性特征，对成层土中轴横受荷桩的水平响应进行分析求解，得到了轴横荷载作用下桩身变形和内力的非线性有限差分解，并采用MATLAB语言编制了计算程序。使用模型试验算例与基于现场试验的有限元算例对非线性解的准确性进行对比验证，结果表明:计算结果与算例数据吻合良好，可靠性较高；采用不同荷载传递模型的计算结果在不同荷载水平下有所差异，在较大荷载水平下桩-土变形的非线性特点不容忽视。 相似文献
4.
对分层弹性地基中端承桩基础按ｗｉｎｋｌｅｒ（温克尔）地基土模型并通过特性分析建立了合理的力学模型。经过动力分析，给出了端承桩横向自振特性及在常轴力与横向地震载荷作用下强迫反应解析解，为具有常轴力与横向地震载荷作用下的无限层弹性地基中端承桩的动力反应分析提供了一种新的解析方法。 相似文献
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6.
对具有任意阶非线性薛定谔方程的行波解进行了研究。给出具有任意阶非线性薛定谔方程的精确解。利用行波变换和辅助函数法把具有任意阶非线性薛定谔方程最终转化为一个非线性常微分方程的解,通过对这个微分方程的研究可以得到具有任意阶非线性薛定谔方程的行波解。具有任意阶非线性薛定谔方程存在的孤立波解、三角孤立波解、扭孤立波解、Jacobi椭圆函数解。得到了具有任意阶非线性薛定谔方程新的Jacobi椭圆函数解。 相似文献
7.
为了寻求一类著名的非线性波动方程utt-kuxx+pu+qu2+su3=0的新精确解。利用齐次平衡法的思想与改进的G′/G展开法,通过对解的形式的巧妙构造可以将方程约化为一组非线性方程组,借助于数学软件Maple强大的符号计算功能得到了方程包括双曲函数解、三角函数周期解、有理数解在内的3种形式的精确解。同时给出了其中一组情况的数值模拟图。这些解对正确理解方程在自然科学中的物理意义具有重要的作用。 相似文献
8.
在垂直方向零应变与垂直方向总荷载不变、忽略骨架颗粒本身的压缩性及骨架颗粒与水分别为均质的假定条件下,推导出均质各向同性多孔介质水平面弹性位移方程及水流方程。它们与传统假定（Jacob假定）下的位移及水流方程在形式上没有区别,只是方程中的系数定义式有所不同。新水流方程中的储水率比旧水流方程中的储水率偏大,但仍可按常数对待。新位移方程的系数也比传统假定下的位移方程的系数大．但也仍为常数。如果采用野外抽水试验来确定储水率,则传统假定下水流方程与新水流方程等价,但利用抽水试验确定的骨架弹性储水率计算地面沉降,则计算值偏大。 相似文献
9.
基于齐次平衡法的思想,利用G′G-展开法求得KdV-Burgers-Kuramoto方程的精确解,这些解更具有一般性,其中包括了双曲函数解、三角函数周期解、有理数解。同时,这些解对于研究湍流运动和不稳定现象有重要意义。为更好的描述这些解,给出了三角函数周期解及扭状解的数值模拟图。 相似文献
10.
王水球 《成都信息工程学院学报》2009,24(3)
运用泛函分析性质以及Fourier变换的方法研究带有周期边界条件的非线性k-s方程在有限时间区间上的精确控制.首先研究线性化k-s方程的精确控制,证明对于任意给定的函数u0∈Hs,uT∈Hs,总能找到一个控制函数h使得线性化k-s方程有解u且满足u(x,0)=u0,u(x,T)=uT;然后结合线性化k-s方程的精确控制,通过定义Fredholm算子并应用Fredholm算子的一些理论找到非线性化k-s方程的控制函数,使其可精确控制. 相似文献
11.
The statistical and distribution characteristics of the responses of a floater and its mooring lines are essential in designing floating/mooring systems.In general,the dynamic responses of offshore structures obey a Gaussian distribution,assuming that the structural system,and sea loads are linear or weakly nonlinear.However,mooring systems and wave loads are considerably nonlinear,and the dynamic responses of hull/mooring systems are non-Gaussian.In this study,the dynamic responses of two types of floaters,semi-submersible and spar platforms,and their mooring lines are computed using coupled dynamic analysis in the time domain.Herein,the statistical characteristics and distributions of the hull motion and mooring line tension are discussed and compared.The statistical distributions of the dynamic responses have strong non-Gaussianity and are unreasonably fitted by a Gaussian distribution for the two floating and mooring systems.Then,the effects of water depth,wave parameters,and low-frequency and wave-frequency components on the non-Gaussianity of the hull motion,and mooring line tension are investigated and discussed.A comparison of the statistical distributions of the responses with various probability density functions,including the Gamma,Gaussian,General Extreme Value,Weibull,and Gaussian Mixture Model(GMM)distributions,shows that the GMM distribution is better than the others for characterizing the statistical distributions of the hull motion,and mooring line tension responses.Furthermore,the GMM distribution has the best accuracy of response prediction. 相似文献
12.
为探讨齿轮系统裂纹故障的非线性动力学机理,研究含裂纹故障的四自由度齿轮系统的动力学特性,考虑时变啮合刚度及非线性间隙的影响,建立含裂纹故障的齿轮四自由度啮合耦合动力学模型,分析裂纹故障对系统啮合刚度的影响;采用谐波平衡法给出系统的解析解,分析裂纹故障及齿轮系统参数对齿轮传动系统的动力学行为的影响.结果表明,裂纹故障能够引起齿轮系统的幅值跳跃、分岔现象和系统共振,从而为齿轮箱的设计及裂纹故障的诊断提供依据. 相似文献
13.
海原-六盘山弧型断裂及其附近最新构造变形演化分析 总被引：4，自引：0，他引：4
利用两时段GPS速度场,用三维非线性有限元方法研究了海原-六盘山弧型断裂带及其附近最新构造变形演化特征。研究得到：1）海原-六盘山断裂带整体表现为左旋运动,海原断裂带左旋活动速率在(2~5.5) mm/a之间,六盘山断裂左旋活动速率约为1.0 mm/a;2）海原断裂带与六盘山断裂带的交接处目前处于强闭锁状态,亦是运动变形差异相对强烈、应变能积累较快的区段,存在强震孕震背景。 相似文献
14.
Shapai Roller Compacted Concrete(RCC) Arch Dam is the highest RCC arch dam of the 20th century in the world with a maximum height of 132m,and it is the only concrete arch dam near the epicentre of Wenchuan earthquake on May 12th,2008.The seismic damage to the dam and the resistance of the dam has drawn great attention.This paper analyzed the response and resistance of the dam to the seismic wave using numerical simulations with comparison to the monitored data.The field investigation after the earthquake and analysis of insitu data record showed that there was only little variation in the opening size at the dam and foundation interface,transverse joints and inducing joints before and after the earthquake.The overall stability of the dam abutment resistance body was quite good except a little relaxation was observed.The results of the dynamic finite element method(FEM) showed that the sizes of the openings obtained from the numerical modeling are comparable with the monitored values,and the change of the opening size is in millimeter range.This study revealed that Shapai arch dam exhibited high seismic resistance and overload capacity in the Wenchuan earthquake event.The comparison of the monitored and simulated results showed that the numerical method applied in this paper well simulated the seismic response of the dam.The method could be useful in the future application on the safety evaluation of RCC dams. 相似文献
15.
郭东屏 《地球科学与环境学报》1988,(3)
本文根据流体动力弥散理论,按照地下水中溶质局部质量守恒原理,采用非线性基函数,导出了求解流体动力弥散问题的一种新的数值法,即等参数溶质质量均衡有限元法。该法与采用同样非线性基函数的等参数里茨(Ritz)法或伽辽全法相比,具有物理意义明确、能准确反映局部质量均衡关系、计算公式简单和易于应用等优点。 相似文献
16.
Lu Youyu 《中国海洋湖沼学报》1991,9(2):184-192
A multiple time scale perturbation method is used to discuss the Lagrangian residual current and residual transport on the
basis of a weakly nonlinear dynamic model of shallow seas. The governing equations for the long-term variation of zero order
“apparent concentration” (which is a linear combination of salinity, temperature of seawater and the concentration of any
tracer which is conservative and passive) and its mean value over tidal cycles are obtained for the system with single tidal
constituent, and for the one with multi-constituents, winds and thermohaline. The equations for the two cases are in the same
form and show this long-term variation resulted from the cumulative effect of residual convection and turbulent diffusion.
The multiple time scale variation of current is caused by tides, winds, and the thermohaline and the nonlinear effects of
the system. The derived set of governing field equations of the Lagrangian current for this multiple time scale system is
also in the same form as that for a single time scale system. 相似文献
17.
Acoustic reverberation signals generated by an experimental explosive source are analyzed by nonlinear dynamical methods. Three characteristic parameters, i.e., the correlation dimension, the largest Lyapunov exponent, and the Koimogorov en-tropy, are estimated in the reconstructed phase space. The results indicate that the reverberation signals are nonlinear. The Volterra adaptive prediction method is introduced to model the oceanic reverberation signals. The reverberation time series can be predicted in short term with small prediction errors. A preliminary conclusion can be reached that the nonlinear low-dimensional dynamic sys-tem model is more suitable for modeling oceanic reverberation than the classical random AR model. 相似文献
18.
A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning （DP） system. In the control force design, a dynamic model of reference linear drift frequency in the horizontal plane is introduced. The dynamic surface control （DSC） is used to design a control strategy for the DP. Compared with the traditional back-stepping methods, the dynamic surface control combined with radial basis function （RBF） neural networks （NNs） can avoid differentiating intermediate variables repeatedly in every design step due to the introduction of a first order filter. Low frequency motions obtained from total motions by a low pass filter are chosen to be the inputs for the RBF NNs which are used to approximate the low frequency wave force. Considering the propellers’ wear and tear, the effect of filtering frequencies for the control force is discussed. Based on power consumptions and positioning requirements, the NN cen-ters are determined. Moreover, the RBF NNs used to approximate the total wave force are built to monitor the disturbances. With the DP assistance, the results of fully coupled dynamic response simulations are given to illustrate the effectiveness of the proposed con-trol strategy. 相似文献
19.
组合导航系统在动态环境下具有强非线性,为提高GNSS/CNS/SINS组合导航系统的导航精度,提出一种基于序贯UKF的多传感器最优融合算法。首先,建立GNSS/CNS/SINS组合导航系统的非线性状态方程及2个子滤波器的线性量测方程;然后,对标准UKF的量测更新过程进行简化,简化UKF算法具有与标准UKF算法相同的滤波精度,且具有计算量低的特性;最后,将序贯滤波算法与简化UKF算法结合,提出多传感器组合导航系统的序贯UKF最优融合算法。仿真结果表明,本文序贯UKF算法不仅可提高系统解算的实时性,并且相对于集中线性卡尔曼滤波算法及经典集中线性UKF算法具有较高的滤波精度。 相似文献
20.
关志强 《广东海洋大学学报》1994,(2)
采用非线性二乘法对国产１２．５系列往复活塞式制冷压缩机的实测性能数据进行拟合，得出描述该系列制冷压缩机性能系数与运行工况之间相关关系的曲面回归方程，为制冷系统的数值计算、动态特性模拟和优化设计提供数学模型。 相似文献