共查询到20条相似文献，搜索用时 203 毫秒
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文章研究了一类捕食者具有阶段结构与食饵具有脉冲扰动的捕食系统,并运用脉冲微分方程的理论给出系统捕食者灭绝周期解的全局渐近稳定性。 相似文献
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本文讨论了一类具有时滞的差分方程的渐近稳定性。利用矩阵性质和不等式技巧给出了该类方程渐近稳定的充要条件。 相似文献
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针对几类重要的随机非线性系统, 提出了一些新的概念,发展了一些基本分析工具, 研究了几类控制器的设计问题. 主要成果包括:(1) 针对一类部分动态不可量测的非线性随机系统,引入了随机输入状态稳定(SISS)的概念, 借助于分析概率理论,发展了随机系统改变能量函数方法, 成功地处理了随机微分中的伊藤项,给出了随机非线性串联系统SISS的小增益类条件. (2) 对一类具有SISS随机逆动态的大规模随机非线性系统,给出了分散自适应输出反馈镇定控制器的构造性设计方法. 既解决了实用镇定问题也解决了渐近镇定问题. 在分散控制框架内,给出了处理随机非线性逆动 态的方法. (3) 对一类具有不稳定零动态的随机非线性系统,引入了随机输入状态可镇定的概念,给出了全局输出反馈镇定控制器构造性设计方法. (4) 对一类具有线性增长的不可量测状态的随机非线性系统,针对方差未知的噪声和一般随机输入,引入了广义随机输入状态稳定(GSISS)的概念,分别给出了随机干扰抑制和渐近镇定的输出反馈控制器的构造性设计方法.(5) 对一般的时滞随机非线性系统, 给出了解存在唯一的判定条件,引入了依概率全局(渐近)稳定的概念及相应的判定准则,丰富了随机时滞非线性系统的控制器设计理论. 对一类不确定随机时变时滞系统,构造性地设计出了自适应输出反馈镇定控制器. 相似文献
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该文运用奇摄动渐近展开的方法讨论了二维具变阻尼阵的Kramers系统尾部轨迹离出点的分布问题,得到了尾部轨迹所满足的随机动力系统;并给出了尾部轨迹离出点分布的渐近表达式。 相似文献
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给出一种用于QPSK系统中可同时完成载波同步的FPGA实现方法。采用纯数字的方法实现,不需要额外同步序列的估计算法进行了改进,对于相位的偏差有较大的容忍裕度。能够自适应的解决载波频率偏移的问题。 相似文献
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给出一种用于QPSK系统中可同时完成载波同步的FPGA实现方法.采用纯数字的方法实现,不需要额外同步序列的估计算法进行了改进,对于相位的偏差有较大的容忍裕度.能够自适应的解决载波频率偏移的问题. 相似文献
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王磊 《中国科学院研究生院学报》2015,(1):110-115
分析相位翻转在直接序列扩频(DSSS)系统信号捕获过程中的影响,分别给出相位翻转对码相位和载波多普勒频率估计影响的数学分析,提出2种能够消除相位翻转影响的DSSS信号捕获算法.与部分相关累加方法相比,延迟共轭相乘方法的捕获性能更加稳定.2种方法均适用于需要考虑相位翻转问题的DSSS系统. 相似文献
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考虑了一类非线性系统的局部镇定问题.首先,利用正则型理论给出一类 3阶非线性系统稳定的充分条件;然后利用得到的结果以及中心流形理论,讨论一类具有特殊形式的 3阶中心流形的非线性系统的镇定问题,并给出中心流形的设计方法以及镇定系统的控制律. 相似文献
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首先建立了弱非完整系统相对于非惯性系的Ｊｏｕｒｄａｉｎ型变分原理，然后给出了弱非完整系统相对于非惯性系在一阶近似情况下的广义Ｎｏｅｔｈｅｒ定理。 相似文献
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《Journal of The Franklin Institute》2022,359(11):5231-5250
This paper utilizes the sliding mode approach to tackle the issue of adaptive control for uncertain switched systems with time-varying delay and actuator faults. Firstly, a kind of mathematical model of switched time-varying delay systems under sudden actuator faults is defined. Then, a linear sliding manifold is constructed, followed by some adequate conditions for exponential stability of the switched systems running on the sliding phase. Furthermore, an adaptive fault-tolerant controller for handling the actuator degradation is designed and the reachability of the established sliding manifold is proved. At last, a series of simulation examples are provided to demonstrate the efficiency of the proposed solution. 相似文献
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An unknown input observer is to estimate the system state of a dynamic system subject to unknown input excitations. In this note, by assuming that at each time instant, the unknown input can be approximated by a polynomial over a local time interval, a finite-time observer is proposed to achieve approximate joint state and input estimation. Both the obtained state and input estimates are moving averages of the present and past output signals. The advantage of the proposed design is that it can be applied to non-minimum phase systems or systems with non-unity relative degree. Notice that most previous unknown input observer designs require the system to be minimum-phase and relative degree one. 相似文献
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对于一个参数进行估计来讲,不仅要考虑估计的精度,还要考虑所得到的估计对于模型拟合的优良程度。通常的损失函数无能为力,而平衡损失函数可以考虑到这两点,本文将在平衡误差损失函数下研究广义Pareto分布参数的Bayes估计问题。在平衡损失函数下导出了参数的Bayes估计并讨论了一类线性形式估计的可容许性和不可容许性。 相似文献
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《Journal of The Franklin Institute》2023,360(7):5292-5318
Specific emitter identification (SEI), as an important problem in situational awareness, identifies emitters via unique characteristics. However, current SEI methods mostly suffer from appropriately setting the trade-off between comprehensiveness and efficiency when extracting fingerprint features. To address the issue, this paper provides a novel SEI framework with a separate representation module. Within the novel framework, manifolds are proposed to be signal representations and multi-level manifold features are extracted as fingerprint features. We first build the SEI model from the nonlinear dynamic perspective, where the SEI process identifies the nonlinear systems via a measurement sequence. Then, we demonstrate that manifolds can represent emitters equivalently and prove the one-to-one correspondence between manifolds and emitter individuals. Hence, manifolds can highlight unique nonlinear dynamic characteristics and simultaneously describe comprehensive system working processes. The coordinate delayed technique and manifold learning methods are employed to reconstruct the phase space and manifold, respectively. For accomplishing the identification task, multi-level manifold features, comprising intrinsic dimension, topological features, conformal features, and Riemannian metric features, are extracted from the reconstructed manifolds and input to an ensemble learning scheme, named Adaboost. Extensive simulation and real-world experiments agree with our analytical conclusions and confirm the proposed method’s efficiency. The results also demonstrate that the proposed method achieves a high recognition accuracy, outstanding adaptability, and strong robustness. 相似文献
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The generalized sampling theorem of Kramer is derived and interpreted in the context of the theory of linear systems satisfying a generalized form of translation invariance. The results are extended to the form of expansions developed by Papoulis and by Campbell. 相似文献
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This paper is concerned with control design for a generalized Takagi–Sugeno fuzzy system. The Takagi–Sugeno fuzzy system generally describes nonlinear systems by employing local linear system representations, while a generalized fuzzy system to be considered in this paper describes even a wider class of nonlinear systems by representing locally nonlinear systems. For such a generalized system, a stabilizing controller design method is proposed by introducing a new class of non-PDC controllers. A non-PDC controller is a generalized controller of PDC one, which is a traditional fuzzy controller. Stabilizing controller design conditions are given in terms of a set of linear matrix inequalities (LMIs), which are easily numerically solvable. A relaxation method is used to reduce the conservatism of design conditions. Finally, numerical examples are given to illustrate our nonlinear control design and to show the effectiveness over other existing results. 相似文献
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《Journal of The Franklin Institute》2023,360(2):1226-1251
For a kind of linear discrete-time-invariant multi-input-multi-output systems with a higher-order relative degree that repetitively operates within a finite time length, the paper exploits a Markov parameters identification method by making use of the multi-operation inputs and outputs obeying a criterion. Simultaneously, an adaptive iterative learning control scheme is architected by formulating the compensator with the sequentially identified Markov parameters and the tracking error in minimizing a performance index consisting of the quadratic tracking error of the next iteration and the compensation cost. Algebraic manipulations including the singular value decomposition of a matrix and the eigenvalues estimation conduct that the identification error of the Markov parameters is monotonically declining as the iteration goes on and a smaller identification ratio in the criterion delivers a faster decline rate. Meanwhile, a rigorous derivation achieves that under the assumption that the initial identification error is within an appropriate range the tracking error is monotonously convergent for the case when the relative degree is unit whilst the tracking error is asymptotically bounded for a positive level for the case where the relative degree is higher. Numerical simulations illustrate the validity and efficiency. 相似文献
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J.L. Finck 《Journal of The Franklin Institute》1947,243(1):1-12
In this paper the concept of reversibility is considered, and it is found that the question of reversibility of a process depends upon the number of independent variables of a system. For a single homogeneous closed phase subject only to mechanical and thermal changes, just two independent variables have been considered in classic thermodynamics. This practice requires that some states be characterized as metastable. Justification is offered for a change in this accepted view. Instead of classifying systems in phases, it is proposed to consider systems on the basis of number of types of transformation.A single gaseous phase subject to dissociation is found to be analogous to a liquid vapor system; each system has three independent variables, such as p, v, T, and equations of state will be of the form ? = F(p, v, T) = G(p, T, x) and v = (Θ(p, T, x) where e is the internal energy and x the degree of transformation. These equations include all metastable states. 相似文献