共查询到10条相似文献,搜索用时 156 毫秒
1.
Pattern recognition and size determination of internal wood defects based on wavelet neural networks
《Computers and Electronics in Agriculture》2010,70(2):142-148
This paper presented the results of a preliminary study on detecting internal wood defects using an ultrasound technique coupled with wavelet transform and artificial neural networks analysis. At room temperature in the laboratory, the type and size of the wood defects in 275 Elm specimens were detected using a RSM-SY5 ultrasonic instrument. The original signals of the Elm specimens were decomposed using wavelet packets, the energy variation of each node in the fifth layer was calculated, and back-propagation artificial neural networks (BP ANN) were trained and employed for wood defect recognition. The energy variation caused by wood defects mostly depends on the degree of the defect's deterioration (i.e., the more serious the wood defect's deterioration, the larger the energy variation). By comparing the energy variation of all 32 node signals in the fifth layer wavelet packet, the variation of the node (5,0) was the largest and contained the most defect information. The node (5,0) was used as the input in back-propagation artificial neural networks in order to detect the type of defects. The accuracy rate for Elm specimens was at least 90%. The same method was used to test the size and position of the hole-defects in Elm specimens with an accuracy rate of at least 80%. 相似文献
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Identification of the 1H-NMR spectra of complex oligosaccharides with artificial neural networks 总被引:1,自引:0,他引:1
B Meyer T Hansen D Nute P Albersheim A Darvill W York J Sellers 《Science (New York, N.Y.)》1991,251(4993):542-544
Artificial networks can be used to identify hydrogen nuclear magnetic resonance (1H-NMR) spectra of complex oligosaccharides. Feed-forward neural networks with back-propagation of errors can distinguish between spectra of oligosaccharides that differ by only one glycosyl residue in twenty. The artificial neural networks use features of the strongly overlapping region of the spectra (hump region) as well as features of the resolved regions of the spectra (structural reporter groups) to recognize spectra and efficiently recognized 1H-NMR spectra even when the spectra were perturbed by minor variations in their chemical shifts. Identification of spectra by neural network-based pattern recognition techniques required less than 0.1 second. It is anticipated that artificial neural networks can be used to identify the structures of any complex carbohydrate that has been previously characterized and for which a 1H-NMR spectrum is available. 相似文献
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为了实现对木材孔洞缺陷的定量检测,在室内常温下,用RSM-SY5非金属超声波检测仪对50个孔洞缺陷的色木试件进行透射检测.通过对超声检测信号的小波变换特征分析,得到32个从低频到高频的小波包系数,提取其各频带内信号的能量变化量,构造一个32维特征向量,作为BP神经网络的输入参数,最后将这些特征输入神经网络进行训练和识别.结果表明:色木孔洞大小的总识别率达到88%;网络仿真的输出结果和目标输出做线性回归分析,得到的相关系数在0.8~0.9之间,训练结果比较理想. 相似文献
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[目的]研究木材干燥过程的Elman神经网络模型。[方法]在人工神经网络理论的基础上,选用Elman神经网络建立木材干燥过程模型。针对木材干燥过程的特点,Elman神经网络利用木材干燥过程材堆的温度、湿度以及对应的木材含水率建立模型。[结果]通过实际干燥过程数据对模型的准确度进行验证,结果表明Elman神经网络利用少量数据就可以建立模型,并且模型预测精度高,对数据的联想记忆和优化能力强。[结论]Elman神经网络建立的木材干燥过程模型准确,对于提高木材干燥过程的控制水平具有重要研究意义。 相似文献
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基于超声波频谱分析技术的木材孔洞缺陷无损检测 总被引:4,自引:0,他引:4
在探讨现有木材无损检测分析方法不足的基础上,根据超声波在木材中的传播规律,提出了用超声波能量衰减和频率成分的改变表征木材缺陷信息的方法,在此基础上用频谱分析处理了超声波信号。通过对木材空洞缺陷进行了多种频谱分析方法对比研究,选用Welch功率谱分析法对红松标准试件进行超声检测。实验结果表明,频谱分析能判断孔洞缺陷的大小和孔洞个数的变化规律,可见缺陷信号频谱丰富。频谱分析能够区分木材孔洞缺陷的大小和个数,而对缺陷的位置区分不明显。 相似文献
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采用传统的人工神经网络模型对深圳证券成份指数进行模拟预测,在此基础上,进一步采用小波函数结合神经网络形成的小波网络对其进行拟合和预测,并对两种预测方法得到的结论误差进行分析、比较。结果显示,小波网络比单纯的神经网络模型预测精度高11.1595。 相似文献
8.
基于空频变换的木材缺陷图像分割 总被引:1,自引:0,他引:1
针对木材缺陷这一自然纹理型事物,为了提取出其缺陷目标部分,进行下一步的分析和识别,采用一种空频变换方法对缺陷图像进行分割。选取虫眼、死节、活节3类木材缺陷图像样本各50个,构造一组多通道的Gabor滤波器对缺陷图像进行滤波,并提取出图像的多方向Gabor能量特征。最后结合模糊聚类算法和数学形态学后处理操作对缺陷图像进行了成功的分割。实验结果表明,此方法对3种木材缺陷图像的平均分割正确率分别达到了95.81%、94.58%、96.52%,证明了该方法的有效性。 相似文献
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提出了一种基于BP神经网络的图书馆病毒检测方法,该方法成功地把BP神经网络的理论引入计算机病毒的检测中。该方法比传统检测技术更有效地对系统信息和文件系统进行语法分析,快速地诊断出被感染病毒以及病毒的类型。 相似文献
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利用BP神经网络和CHRIS高光谱数据反演了富营养化非常严重的太湖梅梁湾地区叶绿素A浓度。首先计算了CHRIS模式2的18个波段与叶绿素A浓度的皮尔森相关系数,选择CHRIS的前5个波段和第13波段的反射率值作为神经网络的输入,以野外测量的叶绿素A浓度为神经网络的输出。实验表明,BP神经网络具有很好的非线性拟合能力,叶绿素A浓度的反演精度相对误差仅为22%,明显优于传统的多项式模型,显示BP神经网络与CHRIS高光谱数据结合的方法在内陆水体水质参数反演领域的应用具有相当的优势。 相似文献