Dr Hess envisages a ray of light travelling down an optical fibre made from two materials: a core with a negative refractive index and an outer sheath with a positive one.
Processing the aluminum weld image from the scanning of the X raynegative can derive the binary image of the weld defects.
利用X射线底片扫描成像法得到铝合金焊缝图像，再通过图像处理方法即可得到焊接缺陷二值图象。
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Conclusion There are varied clinical manifestations in pneumothorax patients with thoracic X-raynegative. CT was the best diagnosis way of the disease.