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1.
In this paper, a nonlinear optimization method is used to explore the finite-time instability of the atmospheric circulation
with a three-level quasigeostrophic model under the framework of the conditional nonlinear optimal perturbation (CNOP). As
a natural generalization of linear singular vector (SV), CNOP is defined as an initial perturbation that makes the cost function
the maximum at a prescribed forecast time under certain physical constraint conditions. Special attentions are paid to the
different structures and energy evolutions of the optimal perturbations. 相似文献
2.
针对一类具有状态约束的非严格反馈高阶非线性系统,研究一种自适应模糊有限时间跟踪控制问题.首先,利用模糊逻辑系统逼近不确定性非线性函数,在此基础上,采用障碍Lyapunov函数,解决状态约束问题,通过障碍加幂积分方法和反步递推技术,提出了一种有限时间控制设计方法.在有限时间Lyapunov稳定意义下,严格证明闭环系统半全局实际有限时间稳定且系统的状态不超出给定的约束边界,并实现了有限时间跟踪控制目标.最后,仿真研究进一步验证了所提出控制方法的有效性. 相似文献
3.
本文研究了具有量化输入信号和未知扰动的非线性系统的有限时间自适应输出反馈动态面控制问题.在控制设计过程中,利用模糊逻辑系统对系统中的非线性项进行逼近.然后引入一种滞回量化器来避免量化信号中的抖振,并且构造模糊观测器来估计系统中不可测的状态.为了提出一种有限时间控制策略,首先给出了半全局实际有限时间稳定的判据.在此基础上,将动态面控制技术与反步法相结合,设计了自适应模糊控制器.该控制器不仅能保证跟踪误差在有限时间内收敛到原点的一个小邻域,而且可以保证闭环系统中所有信号的有界性.最后通过一个仿真实例验证了该控制方法的有效性和可行性. 相似文献
4.
The structural organization of initially random errors evolving in a barotropic tangent linear model, with time-dependent basic states taken from analyses, is examined for cases of block development, maturation and decay in the Southern Hemisphere atmosphere during April, November, and December 1989. The statistics of 100 evolved errors are studied for six-day periods and compared with the growth and structures of fast growing normal modes and finite-time normal modes (FTNMs). The amplification factors of most initially random errors are slightly less than those of the fastest growing FTNM for the same time interval.During their evolution, the standard deviations of the error fields become concentrated in the regions of rapid dynamical development, particularly associated with developing and decaying blocks. We have calculated probability distributions and the mean and standard deviations of pattern correlations between each of the 100 evolved error fields and the five fastest growing FTNMs for the same time interval. The mean of the largest pattern correlation, taken over the five fastest growing FTNMs, increases with increasing time interval to a value close to 0.6 or larger after six days. FTNM 1 generally, but not always, gives the largest mean pattern correlation with error fields. Corresponding pattern correlations with the fast growing normal modes of the instantaneous basic state flow are significant but lower than with FTNMs.Mean pattern correlations with fast growing FTNMs increase further when the time interval is increased beyond six days. 相似文献
5.
本文利用非连续的控制协议,研究了多智能体系统的有限时间一致性与固定时间一致性问题.基于集值映射、微分包含以及Lyapunov稳定性理论,在统一的框架下,给出了多智能体系统达到有限时间一致性和固定时间一致性的判别准则.通过数值仿真,验证了所给协议的有效性. 相似文献
6.
本文研究了多切换模式下混沌系统的有限时同步控制问题.针对多个不同阶实变量混沌系统,研究了其多切换同步行为,给出了有限时多切换组合同步的定义,进而,在给出误差系统的基础上,设计了一类实现快速同步的有限时控制方案,并给出了误差系统有限时稳定的充分条件.最后,仿真结果表明所设计控制方案具有快速收敛性,较好地验证了有效性. 相似文献
7.
本文研究了一类具有随机时滞的受扰马尔科夫跳变线性系统的有限时间稳定性问题.通过引入服从伯努利分布的随机变量刻画了时滞变化的随机特性.本文首先分析了系统的随机有限时间稳定性,基于分析结果设计了反馈控制器,使得系统状态在马尔科夫跳变、随机时滞和外界扰动等并存时,在给定时间内收敛于某一区域而不超过指定的上界值,并可获得该上界的具体值.最后通过数值仿真验证了所提算法的有效性. 相似文献
8.
The localized features on chaotic attractor in phase space and predictability are investigated in thepresent study.It will be suggested that the localized features in phase space have to be considered indetermining the predictability.The notions of the local instability including the finite-time and local-time instabilities which determine the growth rate of error are introduced,and the calculation methodsare discussed in detail.The results from the calculation of the 3-component Lorenz model show thatsuch instability,correspondingly the growth rate of error,varies dramatically as the trajectoriesevolve on the chaotic attractor.The region in which the growth rate of error is small is localizedconsiderably,and is separable from the region in which the growth rate is large.The localpredictability is of important interest.It is also suggested that such localized features may be the maincause for a great deal of case-to-case variability of the predictive skill in the operational forecasts. 相似文献
9.
Zsolt Sándor Bálint Érdi Christos Efthymiopoulos 《Celestial Mechanics and Dynamical Astronomy》2000,78(1-4):113-123
The phase space structure around L
4 in the restricted three-body problem is investigated. The connection between the long period family emanating from L
4 and the very complex structure of the stability region is shown by using the method of Poincarés surface of section. The zero initial velocity stability region around L
4 is determined by using a method based on the calculation of finite-time Lyapunov characteristic numbers. It is shown that the boundary of the stability region in the configuration space is formed by orbits suffering slow chaotic diffusion. 相似文献
10.
In this paper,a nonlinear optimization method is used to explore the finite-time instability of the atmospheric circulation with a three-level quasigeostrophic model under the framework of the conditional nonlinear optimal perturbation (CNOP).As a natural generalization of linear singular vector (SV),CNOP is defined as an initial perturbation that makes the cost function the maximum at a prescribed forecast time under certain physical constraint conditions.Special attentions are paid to the different structures and energy evolutions of the optimal perturbations.The results show that the most instable region of the global atmospheric circulation lies in the midlatitude Eurasian continent.More specially,SV and CNOP in the total energy norm with an optimization time of 2 days both present localness:they are mainly located in the midlatitude Asian continent and its east coast.With extension of the optimization time,SVs are more upstream and less localized in the zonal direction,and CNOPs differ essentially from SVs with broader zonal and meridional coverages; as a result,CNOPs acquire larger kinetic and available potential energy amplifications than SVs in the nonlinear model at the corresponding optimization time.For the climatological wintertime flow,it is seen that the baroclinic terms remain small over the entire time evolution,and the energy production comes essentially from the eddy kinetic energy,which is induced by the horizontal shear of the basic flow.In addition,the effects of SVs and CNOPs on the Eurasian atmospheric circulation are explored.The results show that the weather systems over the Eurasian continent in the perturbed fields by CNOPs are stronger than those by SVs at the optimization time.This reveals that the CNOP method is better in evaluating the instability of the atmospheric circulation while the SV method underestimates the possibility of extreme weather events. 相似文献