共查询到20条相似文献，搜索用时 93 毫秒
1.
We studied the response of harmonically and stochastically excited strongly nonlinear oscillators with delayed feedback bang-bang control using the stochastic averaging method. First, the time-delayed feedback bang-bang control force is expressed approximately in terms of the system state variables without time delay. Then the averaged It6 stochastic differential equations for the system are derived using the stochastic averaging method. Finally, the response of the system is obtained by solving the Fokker-Plank-Kolmogorov （FPK） equation associated with the averaged lt6 equations. A Duffing oscillator with time-delayed feedback bang-bang control under combined harmonic and white noise excitations is taken as an example to illus- trate the proposed method. The analytical results are confirmed by digital simulation. We found that the time delay in feedback bang-bang control will deteriorate the control effectiveness and cause bifurcation of stochastic jump of Duffing oscillator. 相似文献
2.
A minimax optimal control strategy for quasi-Hamiltonian systems with bounded parametric and/or external disturbances is proposed based on the stochastic averaging method and stochastic differential game. To conduct the system energy control, the partially averaged Ito stochastic differential equations for the energy processes are first derived by using the stochastic averaging method for quasi-Hamiltonian systems. Combining the above equations with an appropriate performance index, the proposed strategy is searching for an optimal worst-case controller by solving a stochastic differential game problem. The worst-case disturbances and the optimal controls are obtained by solving a Hamilton-Jacobi-Isaacs （HJI） equation. Numerical results for a controlled and stochastically excited DulTlng oscillator with uncertain disturbances exhibit the efficacy of the proposed control strategy. 相似文献
3.
Rong-hua HUAN Wei-qiu ZHU Yong-jun WU 《浙江大学学报(A卷英文版)》2008,9(3):351-357
A modified nonlinear stochastic optimal bounded control strategy for random excited hysteretic systems with actuator saturation is proposed. First, a controlled hysteretic system is converted into an equivalent nonlinear nonhysteretic stochastic system. Then, the partially averaged Itoe stochastic differential equation and dynamical programming equation are established, respectively, by using the stochastic averaging method for quasi non-integrable Hamiltonian systems and stochastic dynamical programming principle, from which the optimal control law consisting of optimal unbounded control and bang-bang control is derived. Finally, the response of optimally controlled system is predicted by solving the Fokker-Planck-Kolmogorov （FPK） equation associated with the fully averaged Itoe equation. Numerical results show that the proposed control strategy has high control effectiveness and efficiency. 相似文献
4.
A stochastic averaging method for predicting the response of quasi partially integrable and non-resonant Hamiltonian systems to fractional Gaussian noise (fGn) with the Hurst index 1/2<H<1 is proposed. The averaged stochastic differential equations (SDEs) for the first integrals of the associated Hamiltonian system are derived. The dimension of averaged SDEs is less than that of the original system. The stationary probability density and statistics of the original system are obtained approximately from solving the averaged SDEs numerically. Two systems are worked out to illustrate the proposed stochastic averaging method. It is shown that the results obtained by using the proposed stochastic averaging method and those from digital simulation of original system agree well, and the computational time for the former results is less than that for the latter ones. 相似文献
5.
本文研究一类不确定广义随机混杂系统的非脆弱控制问题。在连续子系统的控制器增益存在一般形式的加性摄动情况下,利用多Lyapunov函数和随机Lyapunov函数相结合的方法,确定控制器的增益,使整个混杂系统达到随机稳定。仿真实例验证了本方法的有效性。该方法适用于计算机集成制造系统及交通管理系统。 相似文献
6.
田卫军 《咸阳师范学院学报》2006,21(6):8-11,30
用非协调有限元方法进行定常Navier-Stokes方程的求解,证明了解的稳定性问题,对揭示逼近解的变化规律有重要意义,为数值求解定常Navier-Stokes方程提供了新的思路。 相似文献
7.
A modified Lindstedt-Poincaré(LP) method for obtaining the resonance periodic solutions of nonlinear non-autonomous vibration systems is proposed in this paper. In the modified method, nonlinear non-autonomous equations are converted into a group of linear ordinary differential equations by introducing a set of simple transformations.An approximate resonance solution for the original equation can then be obtained. The periodic solutions of primary, super-harmonic, sub-harmonic, zero-frequency and combination resonances can be solved effectively using the modified method. Some examples, such as damped cubic nonlinear systems under single and double frequency excitation,and damped quadratic nonlinear systems under double frequency excitation, are given to illustrate its convenience and effectiveness. Using the modified LP method, the first-order approximate solutions for each equation are obtained. By comparison, the modified method proposed in this paper produces the same results as the method of multiple scales. 相似文献
8.
实际系统中普遍存在时滞、输入饱和等现象,给控制器设计带来一定难度。通过设计合适的李雅普诺夫函数,考虑广义跳变系统跳变点前后状态不一致、转移概率不完全可知等情况,设计状态反馈控制器。所得控制器保证闭环系统的指数稳定性,所得结果更加具有一般性,并通过仿真算例验证方法的有效性。 相似文献
9.
借助基于二阶高斯-马尔可夫异常位模型的重力异常协方差函数,得到了海洋重力测量中重力异常信号的状态方程．结合实际重力仪的系统状态方程和系统量测方程,提出了级联卡尔曼滤波方法,并将其应用于重力异常畸变信号的校正处理中．在信号处理过程中,首先采用卡尔曼逆滤波恢复含高频干扰的重力异常,然后采用自适应卡尔曼滤波,以重力异常状态方程为系统方程估计实际重力异常值,并与单一卡尔曼逆滤波器的处理结果进行了对比分析．仿真和试验表明,级联卡尔曼滤波方法和单一卡尔曼逆滤波都能在一定程度上减小重力异常信号的畸变,但在相同背景条件下,级联卡尔曼滤波方法的性能优于单一逆卡尔曼滤波． 相似文献
10.
以多刚体动力学理论为基础,推导了自由漂浮状态双臂空间机器人系统的动量矩守恒关系,转化为系统状态方程;结合基于实数编码的遗传算法实现了双臂空间机器人姿态、关节协调运动的近似最优控制算法.通过控制双臂空间机器人的关节运动,可以同时获得载体姿态及机械臂关节期望的终了位置.仿真算例验证了算法的有效性. 相似文献
11.
钢筋混凝土梁桥在地震作用下结构可简化为一多自由度体系，基于状态方程法的一般原理，推导了钢筋混凝土梁桥的自由振动解和强迫振动解，并对结构在平稳白噪声激励下进行了随机地震反应分析。 相似文献
12.
研究非线性地基上圆形薄板受简谐激励的非线性振动问题。按照弹性力学理论建立非线性地基上圆形薄板受简谐激励的动力学方程,利用Galerkin方法将其转化为非线性振动方程,该方程是马休型方程。应用非线性振动的多尺度法求得系统主参数共振的近似解,并进行数值计算。分析阻尼、地基系数、几何参数等对共振响应曲线的影响。 相似文献
13.
考虑用配位法解决一种非线性奇异积分方程的数值解问题。采用Lagrange有理插值方法将原方程离散为代数方程,通过求解该代数方程得到原方程的数值解和逼近解;再通过图像对解的情况进行分析,试图找到解与系数之间的关系。 相似文献
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15.
Hefei Liu 《Structural equation modeling》2018,25(1):41-55
Multivariate heterogenous data with latent variables are common in many fields such as biological, medical, behavioral, and social-psychological sciences. Mixture structural equation models are multivariate techniques used to examine heterogeneous interrelationships among latent variables. In the analysis of mixture models, determination of the number of mixture components is always an important and challenging issue. This article aims to develop a full Bayesian approach with the use of reversible jump Markov chain Monte Carlo method to analyze mixture structural equation models with an unknown number of components. The proposed procedure can simultaneously and efficiently select the number of mixture components and conduct parameter estimation. Simulation studies show the satisfactory empirical performance of the method. The proposed method is applied to study risk factors of osteoporotic fractures in older people. 相似文献
16.
Short-term load forecasting (STLF) plays a very important role in improving the economy and security of electricity system operations. In this paper, a hybrid STLF method is proposed based on the improved ensemble empirical mode decomposition (IEEMD) and back propagation neural network (BPNN). To alleviate the mode mixing and end-effect problems in traditional empirical mode decomposition (EMD), an IEEMD is presented based on the degree of wave similarity. By applying the IEEMD method, the nonlinear and nonstationary original load series is decomposed into a finite number of stationary intrinsic mode functions (IMFs) and a residual. Among these components, the high frequency (namely IMF1) is always so small that it has little contribution to model fitting, while it sometimes has a great disturbance for the STLF. Therefore, the IMF1 is removed in the proposed hybrid method for denoising. The remaining IMFs and residual are forecast by BPNN, and then the forecasting results of each component are combined with BPNN to obtain the final predicted load series. Three groups of studies were done to evaluate the effectiveness of the proposed hybrid method. The results show that the proposed hybrid method outperforms other methods both mentioned in this paper and previous studies in terms of all the three standard statistical indicators considered in this study. 相似文献
17.
Structural equation modeling is a common multivariate technique for the assessment of the interrelationships among latent variables. Structural equation models have been extensively applied to behavioral, medical, and social sciences. Basic structural equation models consist of a measurement equation for characterizing latent variables through multiple observed variables and a mean regression-type structural equation for investigating how explanatory latent variables influence outcomes of interest. However, the conventional structural equation does not provide a comprehensive analysis of the relationship between latent variables. In this article, we introduce the quantile regression method into structural equation models to assess the conditional quantile of the outcome latent variable given the explanatory latent variables and covariates. The estimation is conducted in a Bayesian framework with Markov Chain Monte Carlo algorithm. The posterior inference is performed with the help of asymmetric Laplace distribution. A simulation shows that the proposed method performs satisfactorily. An application to a study of chronic kidney disease is presented. 相似文献
18.
以温度场中斜梁受简谐激励的非线性振动方程为基础,应用非线性振动的多尺度法,求得非线性振动系统1/2亚谐-主参数共振的一次近似解,并进行定常解稳定性分析和数值计算.分析了温度、激励、几何尺寸对1/2亚谐-主参数共振幅频响应曲线的影响. 相似文献
19.
提出一种环境激励下的模态识别方法.具体方法是通过对非平稳随机激励下的线性时不变系统的结构响应进行小波变换,对各级小波系数利用协整理论进行线性合成得到新的信号.若此信号是平稳的,则以它代替原始的结构响应,然后结合平稳随机激励下的模态识别方法--NExT方法和修正的连续最小二乘法,只通过输出信号就可以实现对非平稳随机激励下系统模态参数的识别.仿真结果表明,该方法可以极大程度上消除非平稳随机激励所引起的结构响应的非平稳性,而且具有很高的精度和稳健性. 相似文献