Higher-order spatial correlation coefficients of ultrasonic backscattering signals using partial cross-correlation analysis.
Higher-order spatial correlation coefficients of ultrasonic backscattering signals using partial cross-correlation analysis.
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DOI：
10.1121/10.0000615
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发表时间：
2020-02
期刊：
影响因子：
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通讯作者：
Yongfeng Song;C. Kube;Jie Zhang;Xiongbing Li
中科院分区：
文献类型：
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作者：
Yongfeng Song;C. Kube;Jie Zhang;Xiongbing Li
随机介质中超声反向散射信号的空间相关特性具有重要意义。例如，它们可用于工程材料的微观结构表征和缺陷检测。然而，传统的空间相关系数（SCC）只是一个前序量，并不能捕捉随机介质的真实空间相关性。这是由于忽略了混杂变量（例如非零均值或其他非零奇阶矩）引起的。这里，通过部分互相关分析将 SCC 从零阶推广到一般阶。定义了一系列指标来量化零时滞时的 SCC 曲线和最大时移曲线，它们都是两个传感器位置之间横向间隔的函数。使用不锈钢样品和聚焦超声换能器来验证该方法。散射测量表明，高阶 SCC 可以一致地捕获空间相关性，而零阶 SCC 则不够。显示零阶 SCC 可以预测可能大六倍以上的步长。因此，本方法可以提供对统计相关性和测量不相关反向散射信号的条件的更好理解。
The spatial correlation properties of ultrasonic backscattering signals in random media have important implications. For example, they can be used for microstructural characterization and flaw detection in engineering materials. However, the traditional spatial correlation coefficient (SCC) is only a leading order quantity that does not capture the true spatial correlations of random media. This is caused by neglecting confounding variables such as non-zero means or other non-zero odd-order moments. Here, the SCC is generalized from zeroth- to general-order through partial cross-correlation analysis. A series of indicators are defined to quantify the SCC curve at zero time lag, and the maximum time shift curve, which are both functions of lateral separation between two sensor positions. A stainless-steel specimen and a focused ultrasonic transducer are used to verify the method. Scattering measurements show that the higher-order SCC can consistently capture spatial correlations whereas the zeroth-order SCC is inadequate. The zeroth-order SCC is shown to predict a step size that can be more than six times too large. Thus, the present method can provide better understanding of statistical correlations and conditions to measure uncorrelated backscattering signals.