基于CNNs识别反馈的点阵字符检测方法

针对点阵字符因错误分割导致识别准确率较低的问题,提出了一种基于卷积神经网络(CNNs)识别反馈的点阵字符检测方法。首先采用多尺度窗口获取多个候选区域并建立CNNs对其进行识别,利用投票机制对多个识别结果进行综合决策,然后根据决策结果反向定位点阵字符并完成字符分割,最后提出一种滑动翻转窗口对所有字符进行分割与识别。实验结果表明,该方法在点阵字符的定位准确率和识别率方面都优于传统字符识别方法,分别达到了97.53%和97.50%。

永磁同步电机无位置传感估测的参数扰动校正

为克服宽速变负载运行工况下温度及磁饱和引起的电机参数扰动对永磁同步电机磁链观测器无位置传感器算法辨识精度的影响,实现高性能的矢量控制,首先建立磁链观测器无位置传感器算法位置角估测误差与定子电阻、电感扰动量的解析关系,然后提出一种提高位置角估测精度的d轴电流补偿策略,最后结合电流补偿策略与在线参数辨识算法对无位置传感估测位置角进行扰动校正。试验结果表明,基于本校正策略的无位置传感估测改进算法,在电机参数扰动条件下的位置辨识精度提高了60%以上,并可在宽速变负载运行工况下保持9°以内的偏差。本策略在宽速变负载运行工况下的磁链观测器无位置传感器算法中具有一定的应用价值。

Analytical solution for vertical site response analysis and its validation

Existing studies for site response analysis in geotechnical earthquake engineering have widely concentrated on the horizontal component of the ground motion. However, strong vertical ground motions have been repeatedly observed, resulting in significant vertical compression damage of engineering structures. Furthermore, for the seismic design of critical structures(e.g. large-scale dams and nuclear power plants), the ground motions in all three directions should be considered. Therefore, there is a need to investigate the site response subjected to the vertical component of the ground motion, especially for the seismic design of critical structures. Consequently, in this study, a numerical program for vertical site response analysis is proposed based on the commonly used analytical transfer function method. The proposed program is then validated against well-documented case studies obtained from the Japanese KiK-net(Kiban Kyoshin network) downhole array monitoring system. Results show that the response spectra at the ground surface are well predicted in the low frequency range(<5 Hz), while discrepancies are observed in the high frequency range. However, the high frequency discrepancies do not significantly affect the overall prediction accuracy, as the overall seismic response of geotechnical structures are usually dominated by low frequency vibrations. Furthermore, the limitations in the analysis are also discussed.

软弱地层综合管廊三维非线性地震反应特性研究

软弱地层综合管廊在强震作用下易发生破坏。考虑土体非线性及水的影响,以苏通GIL综合管廊工程为依托,采用三维线性梁单元模拟螺栓与钢筋,对地震动进行幅值标定,建立三维精细化有限元模型,并根据不同地震动输入方式及强度,从衬砌应力分布、张开量及结构损伤角度分析综合管廊非线性地震反应特性。研究结果表明,45°共轭方向与拱腰位置处管廊受力较大,横向、纵向地震动作用下,随着地震动强度的增加,应力增加明显;横向地震动输入对管廊环间张开量的影响较小,当地震动达到峰值附近时,张开量增长明显,并在一定范围内波动;横向地震动对管廊结构损伤的影响较大,峰值加速度达0.3 g时,管廊内部结构在两端连接处及中间支撑处连接点出现拉压变形。