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    奚如春, 邓小梅, 马履一. 油松树体声发射信号特征研究[J]. 北京林业大学学报, 2011, 33(6): 151-156.
    引用本文: 奚如春, 邓小梅, 马履一. 油松树体声发射信号特征研究[J]. 北京林业大学学报, 2011, 33(6): 151-156.
    XI Ru-chun, DENG Xiao-mei, MA Lü-yi. Characteristics of acoustic emission wave parameter of xylem cavitation in Pinus tabulaeformis[J]. Journal of Beijing Forestry University, 2011, 33(6): 151-156.
    Citation: XI Ru-chun, DENG Xiao-mei, MA Lü-yi. Characteristics of acoustic emission wave parameter of xylem cavitation in Pinus tabulaeformis[J]. Journal of Beijing Forestry University, 2011, 33(6): 151-156.

    油松树体声发射信号特征研究

    Characteristics of acoustic emission wave parameter of xylem cavitation in Pinus tabulaeformis

    • 摘要: 为了描述油松木质部空穴化发生、发展和恢复特性,利用声发射技术对自然生长的油松树体进行声发射信号监测,通过声发射仪器探测、记录和分析其声发射信号,系统地研究了其树体木质部空穴化发生的声发射信号特征。结果表明:油松木质部空穴化发生的声发信号为突发性事件,其声发射信号频率在230~270 kHz的频谱带上;声发信号在时间序列上,其日变化特征为06:00至17:00是声发信号的高峰期,18:00至次日06:00是低发期;其季节变化特征为6、8和10月的信号数量比12月要多而且幅度要大;在树体组织空间分布上,树体枝条和树干上部(靠近树梢)的信号多而密集,树干中、下部信号少而稀疏;在信号到达时间上,枝条首先接受到信号,一般枝条信号接收到的时间要比树干信号接收到的时间早1~20 min,但树干部分的信号却没有明显的先后顺序。树体夜间检测到的声发信号是空穴化的导管气穴或气柱水分回填时产生的,说明树木在自然生长环境中,其空穴化的导管(管胞)可以依靠其自身的水分传输机理自行得到适度地修复。树木导管发生空穴化是一种普遍现象,在一定限度内,空穴化并不是一种灾难性事件。

       

      Abstract: In the paper, we aim to provide a quantitative description of characteristics of the cavitation xylem occurrence, development and restore characteristics of Pinus tabulaeformis (Chinese pine). The controlling mechanisms of water consumption in Chinese pine of xylem conduits cavitation and embolism had been studied.The acoustic emission (AE) method had been adapted to check and measure the wave parameter of acoustics emission from xylem conduits cavitation. Its acoustic emission signal had been studied systematically by acoustic emission instruments detected, recorded and analyzed. The results indicated that the xylem cavitation and embolism occurred frequently and paroxysmal in the tree body.Its acoustic emission signal frequency in the spectrum ranged from 230 to 270 kHz; acoustic signals on time sequence, the daily signals variation characteristics were sending at the peak from 06:00 to 17:00. The period from 18:00 to the next day 06:00 was low signal period. Concerning the singal seasonal changing characteristics, the singal number was more and higher in June,August and October than that in December. For spatial distribution in tree body organization, the singal was dense in tree trunk and branches of the upper part (near the treetops), while there was little and sparse signal in the middle and lower part of the tree. For signal arrival time, the branches generally received the signal first and there was 1 to 20 min earlier than that to tree trunk, while there was no visible difference in trunk part.The night detected signals of tree body were the sound of catheter cavitation or a column of water produced when it backfilled trees in the natural growth environment. Its hole turn catheter (tracheids) can rely on its own moisture transmission mechanism to repair itself properly.The acoustic emission wave of xylem cavitation is the water carryforward signal of tree bodies. The xylem embolism resulted in cavitation. Ultrasonic acoustic emissions methods could be used for measuring the signal, according to the result, the necessary water politic for trees would be carried out. The characteristic of water capacitance indicate that the tissues of the trees have the capability to hold water. So the trees could suffer from a considerable degree of watershorting conditions.

       

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