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451.
Dong Zou Wei Hua Zhang Rui Ping Li Gui Ming Mei 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(7):902-917
In order to investigate the damping characteristics of railway-overhead-wire systems, we propose herein an approach based on the continuous wavelet transform (CWT) and two existing formulas concerning Rayleigh damping coefficients (RDCs). In the proposed process, the displacement histories of a real catenary are first obtained by using a set of noncontact photogrammetric devices, following which an exclusive catenary damping ratio related to the first dominant modal component in the catenary response is identified through a complex Morlet CWT. Thereafter, iterative finite-element analysis is conducted to find the optimal RDCs, which involves using two related formulas and the similarity between the catenary displacements obtained by simulation and experimentation. The results of our study demonstrate that this combined approach is constructive, especially for structures with closely spaced modes, such as catenaries. For the case studied herein, the catenary modal damping ratio at 1.19?Hz is approximately 1%, and the mass and stiffness proportional Rayleigh damping coefficients are approximately 0.02845 and 0.00274, respectively. 相似文献
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Convolutional neural networks (CNNs) have been applied in state-of-the-art visual tracking tasks to represent the target. However, most existing algorithms treat visual tracking as an object-specific task. Therefore, the model needs to be retrained for different test video sequences. We propose a branch-activated multi-domain convolutional neural network (BAMDCNN). In contrast to most existing trackers based on CNNs which require frequent online training, BAMDCNN only needs offline training and online fine-tuning. Specifically, BAMDCNN exploits category-specific features that are more robust against variations. To allow for learning category-specific information, we introduce a group algorithm and a branch activation method. Experimental results on challenging benchmark show that the proposed algorithm outperforms other state-of-the-art methods. What’s more, compared with CNN based trackers, BAMDCNN increases tracking speed. 相似文献
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将判识特征值在设计速度和距离按泰勒公式展开,依据判识距离化趋势,用二元三次函数逼近,建立了空间绝对距离、相对距离判识变化数学模型.结果表明:绝对距离判识值随障碍物深度距离增加而增大,随速度增加减小.相对距离判识受深度距离影响小,速度变化影响大,二元二次函数可很好逼近空间距离判识变化规律. 相似文献
457.
This paper presents an adaptive path following control law to steer underactuated ships along a predefined path at a constant
forward speed with uncertain parameters due to changes of added mass matrices. The proposed controller is based on analytic
model predictive control and model reference adaptive control. The Serret-Frenet frame is used to describe the ship dynamics.
The analytic model predictive control provides a systematic method rather than try-and-error method to get appropriate control
parameters to guarantee the stability of the closed-loop system, and the well-defined relative degree is guaranteed by introducing
output-redefinition. An identification algorithm based on model reference adaptive control is used to identify the uncertain
parameters. Numerical simulations are provided to demonstrate the validity of the proposed control law. 相似文献
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A path following controller is proposed to force an underactuated surface ship which is suffering from disturbance to follow a predefined path.The controller is based on analytic model predictive control and unscented Kalman filter(UKF) techniques.The analytic model predictive control provides a systematic method to get appropriate controller parameters to guarantee the stability of the closed-loop system,and the well-defined relative degree is guaranteed by introducing output-redefinition.The UKF is used t... 相似文献
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介绍上承式移动模架的构造、施工特点及工作原理,提出了模架施工中几个关键环节的施工措施,针对上乘式移动模架施工特点提出了混凝土浇筑、预应力张拉、线性控制方面应注意的一些问题,保证了模架施工质量. 相似文献