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31.
32.
The inherent nonlinearities of the rudder servo system(RSS) and the unknown external disturbances bring great challenges to the practical application of fault detection technology. Modeling of whole rudder system is a challenging and difficult task. Quite often, models are too inaccurate, especially in transient stages. In model based fault detection, these inaccuracies might cause wrong actions. An effective approach, which combines nonlinear unknown input observer(NUIO) with an adaptive threshold, is proposed. NUIO can estimate the states of RSS asymptotically without any knowledge of external disturbance. An adaptive threshold is used for decision making which helps to reduce the influence of model uncertainty. Actuator and sensor faults that occur in RSS are considered both by simulation and experimental tests. The observer performance, robustness and fault detection capability are verified. Simulation and experimental results show that the proposed fault detection scheme is efficient and can be used for on-line fault detection. 相似文献
33.
李艳辉 《吉林化工学院学报》2014,(6):24-25
在二语习得的过程中,母语会起到一定的负面影响或干扰作用。但这只是表面现象,实际上母语能够帮助学习者完成语言交际的任务。母语既是外语学习不可或缺的背景和基础,又是可以开发利用的资源。重点探讨了母语文化对外语学习的促进作用。 相似文献
34.
利用均值不等式,给出数列{(1+1/n)^n}有界性证明的新方法,使重要极限的证明得以简化。 相似文献
35.
We investigate the global robust tracking problem via output feedback for a class of cascade nonlinear systems with dynamic uncertainties and non-vanishing disturbances. It does not require a priori knowledge of the sign of the high-frequency gain. A recursive design scheme is presented using the ideas of pseudosign function, Nussbaum-type gain technique and the deadzone method. It is shown that under some conditions, the tracking error can be guaranteed asymptotic to the interval [?ε, ε]?? with arbitrary prescribed ε>0 after a finite time, while keeping all signals of the resulting closed-loop systems bounded. The simulation results demonstrate the effectiveness of the proposed algorithm. 相似文献
36.
Jerzy Surma 《Expert Systems》2015,32(4):546-554
The practice of strategy decision making proves that when the management board is strongly limited in its capacity to take rational actions, specifically in the context of great decision complexity and uncertainty, it is considered good practice to refer to experience through reasoning by analogy. In this paper, we would like to concentrate on supporting strategic decisions in small and medium enterprises (SMEs). The complexity of analogy‐based reasoning has its roots in an attempt to solve new problems based on past cases from a different domain, while we will focus on case‐based approach for a single domain. Additionally, we have chosen case‐based reasoning as a suitable decision‐making paradigm because it is corresponds to managers’ decision‐making behaviour. We present the STRATEGOS case‐based reasoning system for supporting strategic decision making by SMEs management boards and then the system evaluation by the dozens of chief executive officers (CEOs) from SMEs is presented. The results of the survey are promising and show the remarkable correspondence of the proposed solution with expectations and strategic behaviour of CEOs. 相似文献
37.
38.
针对未知的宽频带稀疏信号检测问题,提出了一种直接基于非重构采样值
的压缩自相关检测算法。首先利用压缩感知技术以远低于奈奎斯特采样速率获取信号,在自
相关矩阵检测信号理论的基础上,利用压缩感知中传感矩阵的严格等距特性,推导出基于统
计分布的信号稀疏系数自相关检测算法,从理论上给出了判决门限的选取和虚警概率之间的
关系,并进行了算法复杂度分析。由于无需重构原始信号,该算法直接利用少量的压缩测量
值进行检测,可以有效地提高检测过程的时效性。仿真表明在较低的信噪比时,该算法对未
知信号仍有良好的检测性能。 相似文献
39.
Recursive state estimation for discrete‐time nonlinear systems with event‐triggered data transmission,norm‐bounded uncertainties and multiple missing measurements
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In this paper, we consider the recursive state estimation problem for a class of discrete‐time nonlinear systems with event‐triggered data transmission, norm‐bounded uncertainties, and multiple missing measurements. The phenomenon of event‐triggered communication mechanism occurs only when the specified event‐triggering condition is violated, which leads to a reduction in the number of excessive signal transmissions in a network. A sequence of independent Bernoulli random variables is employed to model the multiple measurements missing in the transmission. The norm‐bounded uncertainties that could be considered as external disturbances which lie in a bounded set. The purpose of the addressed filtering problem is to obtain an optimal robust recursive filter in the minimum‐variance sense such that with the simultaneous presence of event‐triggered data transmission, norm‐bounded uncertainties, and multiple missing measurements; the filtering error is minimized at each sampling time. By solving two Riccati‐like difference equations, the filter gain is calculated recursively. Based on the stochastic analysis theory, it is proved that the estimation error is bounded under certain conditions. Finally, two numerical examples are presented to demonstrate the effectiveness of the proposed algorithm. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
40.
Distributed average computation for multiple time‐varying signals with output measurements
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This paper studies the distributed average computation problem for multiple time‐varying signals with bounded inputs. Based only on relative output measurements, a pair of continuous algorithms with, respectively, static and adaptive coupling strengths are designed and utilized. From the concept of boundary layer approach, the proposed continuous algorithm with static coupling strengths can asymptotically obtain the average value of the multiple reference signals without chattering phenomenon. Furthermore, for the case of algorithms with adaptive coupling strengths, the calculation errors are uniformly ultimately bounded and exponentially converge to a small adjustable bounded set. Finally, a simulation example is presented to show the validity of the theoretical results. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献