According to the propagation rules of the surface cracks and the engineering practices, have been given the practical range of permissible short and long cracks on the tube surfaces.
根据表面裂纹扩展规律及工程实际，给出了管状杆件表面的实际短、长裂纹范围。
2
Research on longrange radio wave propagation plays a significant role in both mobile communication and electromagnetic environment.