【摘要】 林木单根抗拉试验数据经常受到试验环境背景、仪器随机误差、人为操作等各类噪声污染,对根系抗拉力学特性的分析结果影响很大。为了提高根系抗拉力学特性的分析精度,需要对试验数据进行预处理。尽管小波降噪理论日渐成熟,但其在林业根系固土机制研究方面的应用并未得到推广。应用小波变换对油松250标距的单根抗拉试验数据进行降噪研究,分别采用到的降噪研究方法有:3～31点平滑法、非线性小波硬阈值(Hard)法、固定阈值(Fixed)法、最大最小阈值(Mini-max)法及Rig.Sure阈值(sure)法。结果表明:各种窗口宽度的平滑法中,9点平滑法被证明降噪效果更为显著;而基于小波变换的Rig.Sure阈值法能够更为有效地降低试验数据中的噪声信号,保留有效信息,提高试验数据的质量及分析能力。更多还原

【Abstract】 The database of single root tensile test is often confused by a series of noise because of test environment,testing machine random error,artificial operation,which greatly influences accurate analytical result.In order to improve analytical precision,the data is needed to be pretreated.The purpose of the study is to eliminate noise of root tensile test data of Pinus tabulaeformis with gauge length 250mm by wavelet analysis.Several multi-resolution wavelet de-nosing methods are applied,including from 3 to 31 point smoothing method,hard threshold method,fixed threshold method,mini-max threshold method and rigorous sure threshold method.Results show that among various window width of smoothing methods,9 point smoothing method is proved to have more marked de-noising effect.In addition,the wavelet transform has particular advantage on noise elimination of the database of single root tensile test while reserving the useful information of data,thus improving the quality of test data and analytical accuracy.更多还原