Nonlinear Dynamic Characteristics Analysis and Adaptive Avoid Vortex - Coordinated Optimal Control of Hydropower Units Grid Connection

2021 ◽  
Author(s):  
Yousong Shi ◽  
Jianzhong Zhou ◽  
Yongchuang Zhang
Keyword(s):  
Optimal Control ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Grid Connection ◽  
Nonlinear Dynamic Characteristics ◽  
Characteristics Analysis ◽  
Dynamic Characteristics Analysis

Nonlinear dynamic characteristics and control of Galfenol-Shape Memory Alloy composite plate subjected to stochastic excitation

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1547-1554
Author(s):  
Xiao-Huan Li ◽  
Fang Liu ◽  
Jia Xu ◽  
Zhi-Wen Zhu
Keyword(s):  
Optimal Control ◽  
Dynamic Characteristics ◽  
Control Strategy ◽  
Nonlinear Dynamic ◽  
Composite Plate ◽  
Vibration Reduction ◽  
Stochastic Excitation ◽  
Optimal Control Strategy ◽  
Nonlinear Dynamic Characteristics ◽  
And Control

In this paper, the nonlinear dynamic characteristics and control of a Galfenol-shape memory alloy (SMA) composite plate under stochastic excitation are studied. New nonlinear differential terms are applied in the constitutive modeling of Galfenol alloy and SMA, and the nonlinear dynamic model of the composite system is developed. The drift coefficient and the diffusion coefficient are calculated to obtain the steady-state probability density function of the system, and finally the optimal control strategy is proposed to improve the effects of vibration reduction. Numerical simulation and experiments results show that the system has abundant nonlinear dynamic characteristics, including stochastic Hopf bifurcation and limit cycle bifurcation. The stochastic optimal control strategy can improve the effects of vibration reduction efficiently. These results are helpful for the application of Galfenol-SMA composite structures.

Dynamic Characteristics Analysis of Cable-Rib Tension Deployable Antenna

2016 ◽  
Author(s):  
Liu Ruiwei ◽  
Hongwei Guo ◽  
Zhang Qinghua ◽  
Rongqiang Liu ◽  
Tang Dewei
Keyword(s):  
Dynamic Characteristics ◽  
Structural Parameters ◽  
Element Model ◽  
Structure Design ◽  
Antenna Structure ◽  
Characteristics Analysis ◽  
New Type ◽  
Dynamic Characteristics Analysis ◽  
The Finite Element Model ◽  
Weight Dynamic

Balancing stiffness and weight is of substantial importance for antenna structure design. Conventional fold-rib antennas need sufficient weight to meet stiffness requirements. To address this issue, this paper proposes a new type of cable-rib tension deployable antenna that consists of six radial rib deployment mechanisms, numerous tensioned cables, and a mesh reflective surface. The primary innovation of this study is the application of numerous tensioned cables instead of metal materials to enhance the stiffness of the entire antenna while ensuring relatively less weight. Dynamic characteristics were analyzed to optimize the weight and stiffness of the antenna with the finite element model by subspace method. The first six orders of natural frequencies and corresponding vibration modes of the antenna structure are obtained. In addition, the effects of structural parameters on natural frequency are studied, and a method to improve the rigidity of the deployable antenna structure is proposed.

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