Asphalt mow strips are typically used as vegetation barriers around guardrail posts in the design of roadside safety structures. Asphalt mow strips have historically been modeled as a rigid layer in simulations;this a...Asphalt mow strips are typically used as vegetation barriers around guardrail posts in the design of roadside safety structures. Asphalt mow strips have historically been modeled as a rigid layer in simulations;this assumption results in significant ground level restraint on the guardrail post. However, experiments have shown that asphalt rupture should be considered in the analysis of the response of guardrail posts embedded in mow strips. The present study investigates the effect of asphalt material properties and mow strip geometry on guardrail post performance using finite element simulations. Numerical simulations are performed and correlated with results from static experiments and material testing. The test simulations and experimental results are used to evaluate the response of guardrail posts with various mow strip designs to predict the level of restraint from the asphalt layer. The model is then used to investigate the effects of asphalt material properties and mow strip geometry on the overall performance of the system. The results demonstrate that including asphalt rupture in numerical simulations is essential in accurately predicting the behavior of guardrail posts installed in asphalt mow strips. In addition, mow strip geometry along with asphalt material properties significantly affect the guardrail post response.展开更多
为了实现对高速公路立柱端面导波信号的自动识别,进而实现立柱的埋深检测,对立柱端面处导波信号的相位特性进行了分析研究。通过推导计算反射系数得出端面回波信号与激励脉冲信号反相的相位特性。采用基于Gabor字典的匹配追踪算法分别对...为了实现对高速公路立柱端面导波信号的自动识别,进而实现立柱的埋深检测,对立柱端面处导波信号的相位特性进行了分析研究。通过推导计算反射系数得出端面回波信号与激励脉冲信号反相的相位特性。采用基于Gabor字典的匹配追踪算法分别对ABAQUS有限元仿真信号和实测导波信号进行了稀疏分解,通过所得匹配原子的相位参数验证了回波信号的相位特性,其中实测信号为分别用64 k Hz和128 k Hz的T(0,1)模态导波对埋地立柱和自由立柱进行检测所得。仿真与实测信号的试验结果与理论分析相吻合,回波信号的相位特性为导波检测中的信号处理技术提供了新的途径和方法。展开更多
超声导波在高速公路护栏立柱检测中存在信噪比低、回波中特征信号不明显等问题,为此,提出一种改进的子空间匹配追踪算法(ISMP),利用回波信号的先验信息在过完备Chirp原子库上得到每次迭代的强相关原子集,经过迭代得到待匹配信号的最佳...超声导波在高速公路护栏立柱检测中存在信噪比低、回波中特征信号不明显等问题,为此,提出一种改进的子空间匹配追踪算法(ISMP),利用回波信号的先验信息在过完备Chirp原子库上得到每次迭代的强相关原子集,经过迭代得到待匹配信号的最佳时频原子,从而实现对立柱回波信号的特征提取。通过对中心频率为128 k Hz的检测信号进行算法验证,结果表明,ISMP可以有效提取出回波信号的特征原子,所得检测长度与实际测量误差小于1%,满足工程检测要求。展开更多
文摘Asphalt mow strips are typically used as vegetation barriers around guardrail posts in the design of roadside safety structures. Asphalt mow strips have historically been modeled as a rigid layer in simulations;this assumption results in significant ground level restraint on the guardrail post. However, experiments have shown that asphalt rupture should be considered in the analysis of the response of guardrail posts embedded in mow strips. The present study investigates the effect of asphalt material properties and mow strip geometry on guardrail post performance using finite element simulations. Numerical simulations are performed and correlated with results from static experiments and material testing. The test simulations and experimental results are used to evaluate the response of guardrail posts with various mow strip designs to predict the level of restraint from the asphalt layer. The model is then used to investigate the effects of asphalt material properties and mow strip geometry on the overall performance of the system. The results demonstrate that including asphalt rupture in numerical simulations is essential in accurately predicting the behavior of guardrail posts installed in asphalt mow strips. In addition, mow strip geometry along with asphalt material properties significantly affect the guardrail post response.
文摘为了实现对高速公路立柱端面导波信号的自动识别,进而实现立柱的埋深检测,对立柱端面处导波信号的相位特性进行了分析研究。通过推导计算反射系数得出端面回波信号与激励脉冲信号反相的相位特性。采用基于Gabor字典的匹配追踪算法分别对ABAQUS有限元仿真信号和实测导波信号进行了稀疏分解,通过所得匹配原子的相位参数验证了回波信号的相位特性,其中实测信号为分别用64 k Hz和128 k Hz的T(0,1)模态导波对埋地立柱和自由立柱进行检测所得。仿真与实测信号的试验结果与理论分析相吻合,回波信号的相位特性为导波检测中的信号处理技术提供了新的途径和方法。
文摘超声导波在高速公路护栏立柱检测中存在信噪比低、回波中特征信号不明显等问题,为此,提出一种改进的子空间匹配追踪算法(ISMP),利用回波信号的先验信息在过完备Chirp原子库上得到每次迭代的强相关原子集,经过迭代得到待匹配信号的最佳时频原子,从而实现对立柱回波信号的特征提取。通过对中心频率为128 k Hz的检测信号进行算法验证,结果表明,ISMP可以有效提取出回波信号的特征原子,所得检测长度与实际测量误差小于1%,满足工程检测要求。
