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首页> 外文会议>International Symposium on Nondestructive Testing of Wood; 20000913-20000915; Sopron; HU >Microwave polarimetry based wood scanning
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Microwave polarimetry based wood scanning

机译：基于微波极化的木材扫描

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We describe a method to detect knots and faults in wood logs based on microwave measurements and the depolarising properties of wood. The depolarisation is an effect of the anisotropy in the dielectric properties of wood, which is caused by the fibre structure. The measurements are made in the frequency domain where a discrete reflection spectrum is sampled. By transforming the frequency spectrum into the time domain the spatial distribution of the reflections appear. The wave is transmitted in a pure linear polarisation, tilted to 45° relative to the fibre direction. For each discrete frequency all available information is measured for the reflected field and therefore it is possible to calculate the complex polarisation ratio and the state of polarisation which are the quantities containing the most visible information. The measurements are one dimensional and by combining measurements from different directions we create tomographic slice images of the inner structure of a log. Our measurements has showed the possibility to follow the extension of knots in a log using only a iso-surface visualisation. The used equipment is working at low intensity and is therefore virtually harmless to human beings, furthermore it is portable and can be operated by one single person.
机译：我们描述了一种基于微波测量和木材的去极化特性来检测木材原木中的结和断层的方法。去极化是木材介电性能中各向异性的影响，这是由纤维结构引起的。在采样离散反射光谱的频域中进行测量。通过将频谱变换到时域，可以显示反射的空间分布。波以纯线性极化传输，相对于光纤方向倾斜45°。对于每个离散频率，针对反射场测量所有可用信息，因此可以计算复极化率和极化状态，这是包含最可见信息的量。测量是一维的，并且通过组合来自不同方向的测量，我们创建了原木内部结构的断层图像。我们的测量结果表明，仅使用等值面可视化，就可以遵循原木中结的延伸。所使用的设备在低强度下工作，因此实际上对人类无害，此外它是便携式的并且可以由一个人操作。

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