面向探地雷达应用的活立木木材介电常数受主要应用条件的影响  

Influence of main application conditions on the permittivity of standing trees for GPR applications

作　　者：李怡娜 徐国祺[1] 王立海[1] 阚相成 谢军明 LI Yina;XU Guoqi;WANG Lihai;KAN Xiangcheng;XIE Junming(College of Engineering&Technology,Northeast Forestry University,Harbin 150040,Heilongjiang,China)

机构地区：[1]东北林业大学工程技术学院,黑龙江哈尔滨150040

出　　处：《中南林业科技大学学报》2022年第4期152-161,共10页Journal of Central South University of Forestry & Technology

基　　金：国家自然科学基金项目(31570547)。

摘　　要：【目的】目前,探地雷达常被应用于活立木缺陷、健康水平以及根系分布等的检测,检测系统中通常默认介电常数为固定值,但经初步研究发现,活立木的介电常数受环境及自身性质等的影响并不是一成不变的,在检测中使用默认的介电常数值会降低检测的准确性。因此,探究在不同应用条件下的活立木木材介电常数变化,建立各因素与介电常数值相关模型可为后续探地雷达检测活立木的应用中提供高精度的参考依据。【方法】本研究选用从黑龙江省星火林场采集的红松、樟子松、大青杨和水曲柳原木试件,根据探地雷达的应用条件,采用Agilent 4294A型介质频谱测试仪测量试件在不同含水率(范围为10%~100%)、不同温度(范围为-15~20℃)、不同外电场频率(范围为40 Hz~110 MHz)下的介电常数。分析不同应用条件下木材介电常数的变化趋势,并基于SPSS软件进行相关性分析,建立介电常数和各因素间的回归模型。【结果】木材含水率、外电场频率和环境温度对4种木材介电常数的影响规律相似。1)随着木材含水率的增加,介电常数呈现出增大的趋势。当含水率低于纤维饱和点时,介电常数缓慢增加;含水率高于纤维饱和点时,介电常数增加的速率变快。2)随着环境温度的增加,木材的介电常数整体呈现出增大的趋势。当含水率高于纤维饱和点时,介电常数值在0℃处出现突变。3)介电常数与外电场频率呈负相关关系,且随着频率的增大介电常数的下降趋势逐渐趋于平缓。4)在此温度区间内,介电常数与频率和含水率呈较为显著的相关性。通过回归分析,建立了介电常数的回归方程。【结论】实验结果表明环境温度、木材含水率和外电场频率均会对木材的介电常数造成影响。介电常数与含水率、环境温度呈正相关,与外电场频率呈负相关关系。含水率和外电场频率对木材的介电�【Objective】At present,ground-penetrating radar is often used to detect the defects,health level and root distribution of living trees.The detection system usually defaults to a fixed value of dielectric constant.However,preliminary studies have found that the dielectric constant of standing wood is not constant due to the environment and its own properties.Using the default dielectric constant value in the test will reduce the accuracy of the test.Therefore,exploring the permittivity changes of living wood under different application conditions,and establishing numerical correlation models between various factors and permittivity can provide high-precision references for the subsequent application of GPR in detecting living wood.【Method】In this study,specimens of Pinus koraiensis,Pinus sylvestris,Populus ussuriensis and Fraxinus mandshurica collected from the Starfire Forest Farm in Heilongjiang Province were used.According to the application conditions of the ground-penetrating radar,the Agilent 4294A dielectric spectrum tester was used to measure the moisture content of the specimens(range 10%-100%),the dielectric constant under different temperatures(range-15℃-20℃),and different external electric field frequencies(range 40 Hz-110 MHz).Then the study analyzed the changes of wood dielectric constant under different application conditions,carried out correlation analysis based on the SPSS software and established a regression model between dielectric constant and various factors.【Results】The influences of wood moisture content,external electric field frequency and ambient temperature on the dielectric constant of the four types of wood were similar.1)As the moisture content of wood increased,the dielectric constant showed an increasing trend.When the water content was lower than the fiber saturation point,the dielectric constant increased slowly;when the water content was higher than the fiber saturation point,the increase of the dielectric constant became faster.2)As the ambient temperature incre

关 键 词：活立木木材介电常数 木材含水率 环境温度 外电场频率 相关性分析 

分 类 号：S758[农业科学—森林经理学]