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151.
介绍了用自适应LMS滤波器离线辨识六面体单元柔性结构模型和逆模型的方法。文中论述了自适应滤波理论和自适应逆控制之间的关系,讨论了LMS算法,并以实验法测得的六面体单元柔性结构随机振动数据为基础对其模型和逆模型进行了辨识,为进一步开展该结构的自适应逆控制研究奠定了基础。 相似文献
152.
ADAPTIVE MESHLESS METHOD BASED ON LOCAL FIT TECHNOLOGY 总被引:1,自引:0,他引:1
LouLuliang ZengPan 《Acta Mechanica Solida Sinica》2005,18(2):164-172
An h-adaptive meshless method is proposed in this paper. The error estimation is based on local fit technology, usually confined to Voronoi Cells. The error is achieved by comparison of the computational results with smoothed ones, which are projected with Taylor series. Voronoi Cells are introduced not only for integration of potential energy but also for guidance of refinement.New nodes are placed within those cells with high estimated error. At the end of the paper, two numerical examples with severe stress gradient are analyzed. Through adaptive analysis accurate results are obtained at critical subdomains, which validates the efficiency of the method. 相似文献
153.
GPS导航解算中常采用最小二乘算法。由于导航解算中存在观测异常(粗差),采用的模型精度很难满足用户需求,而高动态用户需求的精度却不断提高,为此文中提出一种利用神经网络的非线性逼近能力,在顾及观测信息权阵的条件下,利用Hopfieid神经网络进行GPS导航解算的新算法。该算法具有很好的抗差性和自适应性,能较好地抑制观测粗差对导航解的影响。计算结果证明了该算法的有效性。 相似文献
154.
This paper presents an indirect adaptive stabilization scheme forfirst-order continuous-time systems under saturated input which isdescribed by a sigmoidal function. The singularities are avoided througha modification scheme for the estimated plant parameter vector so thatits associated Sylvester matrix is guaranteed to be nonsingular andthen the estimated plant model is controllable. The modificationmechanism involves the use of a hysteresis switching function. Analternative hybrid scheme, whose estimated parameters are updated atsampling instants is also given to solve a similar adaptivestabilization problem. Such a scheme also uses hysteresis switching formodification of the parameter estimates so as to ensure thecontrollability of the estimated plant model. 相似文献
155.
本文重点研究了卡尔曼滤波在静电陀螺监控器(ESGM)参数估计应用中滤波发散的问题。由于系统本身和外部条件的不确定性,很难对系统各状态进行准确的数学描述,造成滤波器不稳定甚至发散。本文提出一种自适应鲁棒滤波方法,并应用于ESGM的初始标定。研究结果表明,应用该算法,可以有效地抑制由于模型不准而产生的滤波发散现象,大大提高了参数估计的精度。 相似文献
156.
157.
基于Rodrigues参数的陀螺体受控运动 总被引:1,自引:0,他引:1
经典刚体动力学中表示刚体姿态的参数中,Euler角、Cardan角和Euler参数在工程技术中使用最为普遍.近期在航天器姿态控制问题中使用Rodrigues参数的报道也引起注意,Rodrigues参数以其表达形式简明和代数运算特点而具有独特优点.航天器姿态控制系统必须具有自适应性以适应参数的变化,建立用Rodrigues参数表达的无力矩陀螺体受控运动方程,提出基于Rodrigues参数的自适应姿态控制方案,并应用Lyapunov定理证明受控运动的渐近稳定性。 相似文献
158.
Shock waves from an open-ended shock tube with different shapes 总被引:1,自引:0,他引:1
A new method for decreasing the attenuation of a shock wave emerging from an open-ended shock tube exit into a large free
space has been developed to improve the shock wave technique for cleaning deposits on the surfaces in industrial equipments
by changing the tube exit geometry. Three tube exits (the simple tube exit, a tube exit with ring and a coaxial tube exit)
were used to study the propagation processes of the shock waves. The detailed flow features were experimentally investigated
by use of a two-dimensional color schlieren method and by pressure measurements. By comparing the results for different tube
exits, it is shown that the expansion of the shock waves near the mouth can be restricted by using the tube exit with ring
or the coaxial tube exit. Thus, the attenuation of the shock waves is reduced. The time histories of overpressure have illustrated
that the best results are obtained for the coaxial tube exit. But the pressure signals for the tube exit with ring showed
comparable results with the advantage of a relatively simple geometry. The flow structures of diffracting shock waves have
also been simulated by using an upwind finite volume scheme based on a high order extension of Godunov's method as well as
an adaptive unstructured triangular mesh refinement/unrefinement algorithm. The numberical results agree remarkably with the
experimental ones. 相似文献
159.
Spatial,Hysteretic, and Adaptive Host–Guest Chemistry in a Metal–Organic Framework with Open Watson–Crick Sites
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Xiao‐Rong Lin Wei Chen Prof. Guang‐Hui Chen Prof. Xiao‐Chun Huang Prof. Dan Li 《Angewandte Chemie (International ed. in English)》2015,54(36):10454-10459
Biological and artificial molecules and assemblies capable of supramolecular recognition, especially those with nucleobase pairing, usually rely on autonomous or collective binding to function. Advanced site‐specific recognition takes advantage of cooperative spatial effects, as in local folding in protein–DNA binding. Herein, we report a new nucleobase‐tagged metal–organic framework (MOF), namely ZnBTCA (BTC=benzene‐1,3,5‐tricarboxyl, A=adenine), in which the exposed Watson–Crick faces of adenine residues are immobilized periodically on the interior crystalline surface. Systematic control experiments demonstrated the cooperation of the open Watson–Crick sites and spatial effects within the nanopores, and thermodynamic and kinetic studies revealed a hysteretic host–guest interaction attributed to mild chemisorption. We further exploited this behavior for adenine–thymine binding within the constrained pores, and a globally adaptive response of the MOF host was observed. 相似文献
160.
In this paper, the leader-following distributed consensus control problem is addressed for general linear multi-agent systems with heterogeneous uncertain agent dynamics and switched leader dynamics. Different from most existing results with a single linear time-invariant (LTI) leader dynamics, the leader dynamics under consideration is composed by a family of LTI models and a switching logic governing the switches among them, which is capable of generating more diverse and sophisticated reference signals to accommodate more complicated consensus control design tasks. A novel distributed adaptive switching consensus protocol is developed by incorporating the model reference adaptive control mechanism and arbitrary switching control technique, which can be synthesized by following a two-layer hierarchical design scheme. A numerical example has been used to demonstrate the effectiveness of the proposed approach. 相似文献