The geometrical relation of elliptic imaging is studied for welding seam image of the butt welds in straight tubes . the region model of welding seam image is proposed , it furnishes a evidence theory to further process to welding seam image 哈尔滨工程大学博士学位论文一针对具体的钢管直管对接焊缝图象，研究了其椭圆成象的几何关系，提出了焊缝图象区域模型，为进一步处理焊缝图象提供了理论依据。
3 according to analysis on the reason for failure of joints , improved measures for new joints are presented , the following phases are included , improved butt welding design , improved technology and welding sequence for butt welding seam , intensive strength checking for butt welding seam , intensive quality inspection for butt welding seam (三)通过对节点破坏成因的分析，提出了新型节点的改进措施，包括四个方面：改进对接焊缝的设计、改进对接焊缝的焊接工艺和焊接顺序、加强对接焊缝的强度校核、加强对接焊缝的质量检测。
The commonly used methods of connections , especially the high - strength bolted connection and welding with bolting mixed connections are discussed in more detail . the analysis for the problems , such as partial penetrated butt weld and welding deformation is also discussed in the paper 对工程中采用较多连接如高强度螺栓连接、栓-焊混合连接等作了较深入分析；对工程中容易出现问题连接如不焊透的对接焊缝计算方法及可能出现的焊接变形及处理等问题也作了较深入探讨。
