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【目的】比较超声发射不同指标应用效果，并从复杂信号中区分木质部管道空穴化信息，为超声发射技术实时无损监测树木栓塞形成生理机制提供理论参考。【方法】采用 8 通道 Micro-II 超声发射系统实时监测兴安落叶松（Larixgmelinii）和红松（Pinus koraiensis）枝段木质部超声发射信号。对比分析以上树种 4 个幅值范围计数、能量和幅值累计信号，信号相对速率分布特征。以数学方法寻找各幅值范围 3 种指标信号采集结束点，对脱水后期可能的干扰信号进行过滤。对比信号过滤前、过滤后的以上各幅值范围指标及相应总信号确定的表征木质部栓塞脆弱性的 P50。【结果】①兴安落叶松和红松 40 ~ 50 d B 和 50~ 60 d B 计数、能量和幅值累计信号曲线较相应的总信号分别提前 0~ 5h，10~ 25 h；而 35~ 40 d B 和≥60 d B 分别推迟 5~ 35 h，45~ 60 h。②2 个树种 40 ~ 50 d B 和 50 ~ 60 d B 3 种指标相对速率分布特征与相应总信号基本一致，且能量相对速率最大值是相应总信号值的 2/5~ 3/5，明显高于 35 ~ 40 d B 和≥60 d B。③兴安落叶松未过滤或过滤3 种指标总信号计算的 P50无显著差异，值的范围分别为-2.92 ~ -2.96 MPa、-2.73 ~ -2.74 MPa。红松未过滤以上指标总信号计算值无显著差异，值的范围是-3.60 ~ -3.84 MPa；而过滤后能量总信号计算值显著高于幅值总信号，值在-3.40 ~ -3.83 MPa 之间。④2 个树种过滤后 3 种指标计算的 P50高于相应未过滤值。其中≥60 d B 未过滤或过滤 3 种指标计算的 P50与相应总信号值相差最大，而其余幅值未过滤或过滤以上指标计算值与相应总信号值差异不显著（除红松 50 ~ 60 d B 过滤幅值）。【结论】幅值特征归类区分的 40 ~ 50 d B 和 50 ~ 60 d B 信号更适用于栓塞脆弱性分析。“数学法”进行信号过滤未显著改变 40 ~ 50 d B 和 50 ~ 60 d B 栓塞脆弱性计算结果以及树种间栓塞脆弱性差异。
【Objective】 The purpose of this study is to compare the application effects of different indices of ultrasonic emission and to distinguish cavitational information of xylem pipes from complex signals to provide theoretical reference for the real-time nondestructive monitoring of the physiological mechanism of tree embolization by ultrasonic emission. 【Method】 The ultrasonic signals of xylem in Larix gmelinii and Pinus koraiensis branches were monitored in real time using 8-channel Micro-II system. Comparative analysis of the above four kinds of species range of amplitude count, energy and amplitude of the cumulative signal, the signal relative rate distribution. To find out the end points of the three kinds of index signal acquisition in each amplitude range mathematically, the possible interference signals in the later stage of dehydration are filtered. Before comparing the signal filtering, filtering the above amplitude range indicators and the corresponding total signal to determine the vulnerability of xylem embolism P50. 【Result】 ①The larch and Korean pine were planted 40-50 d B and 50-60 d B, respectively. The energy and amplitude cumulative signal curves were 0-5 h and 10-25 h earlier than the corresponding total signals, respectively. d B and ≥60 d B were postponed 5 ~ 35 h, 45 ~ 60 h. ② The distribution characteristics of the relative rates of the three species 40 ~ 50 d B and 50 ~ 60 d B were basically the same as the corresponding total signals, and the maximum relative energy rate was 2/5 ~ 3/5 of the corresponding total signal, which was significantly higher Between 35 and 40 d B and ≥60 d B. ③ Porphyrin larch did not filter or filter the three indicators of the total signal calculated P50 no significant difference, the value range of -2.92 ~ -2.96 MPa, -2.73 ~ -2.74 MPa. The results showed that there was no significant difference between the calculated values of the total signal of the un-filtered korean pine and the value of -3.60 ~ -3.84 MPa, while the filtered total energy of the signal was significantly higher than the total amplitude of the signal, with the value of -3.40 ~ -3.83 MPa between. ④ The P50 values of three kinds of indexes after filtering by 2 species were higher than the corresponding unfiltered values. Among them, the difference between P50 calculated by the three indicators of no filtering or filtering and the corresponding total signal value was the largest, while the remaining amplitude was not filtered or filtered. The difference between the calculated value and the corresponding total signal value was not significant d B filtered amplitude). 【Conclusion】 The 40-50 d B and 50-60 d B signals distinguished by amplitude classification are more suitable for the analysis of embolic vulnerability. Signal filtering in the “mathematical method” did not significantly alter the calculated results of embolism fragility at 40-50 d B and 50-60 d d, as well as differences in emboli fragility between species.