Based on results of theoretical analysis, a new method of transmission tomography of pipeline surface defects using ultrasound waves propagating along the pipeline walls is proposed. The waves are excited by a source and received by sensors that are located on ring-shaped lines and spaced along the tube surface. These waves propagating along the pipe surface represent either left or right handed rectilinear cylindrical waves like torsion waves. When a defect arises on the pipeline surface, the resulting waves are accompanied by changes in their shadow projections at the controlled pipe end. The problem of defect tomography is to determine locations and forms of defects using the backward projections. The physical feature of this method is that unlike traditional tomography, these projections arise on mutually intersecting left and right handed trajectories. The problem is solved by multiple joining of cylindrical pipe sections unfolded onto the plane in which all wave paths become rectilinear. A number of examples given in the paper confirm the possibility of restoration of locations and forms of various defects by the proposed method.

中文翻译：

---

管道表面缺陷的无损透射层析成像

基于理论分析结果，提出了一种利用沿管道壁传播的超声波对管道表面缺陷进行透射层析成像的新方法。波由源激发并由位于环形线上并沿管表面间隔开的传感器接收。这些沿管表面传播的波代表左旋或右旋直线圆柱波，如扭转波。当管道表面出现缺陷时，所产生的波浪伴随着它们在受控管端的阴影投影的变化。缺陷断层扫描的问题是使用反向投影确定缺陷的位置和形式。这种方法的物理特点是不同于传统的断层扫描，这些投影出现在相互交叉的左手和右手轨迹上。该问题通过将展开到所有波路径变为直线的平面上的圆柱形管段进行多重连接来解决。论文中给出的一些例子证实了通过所提出的方法修复各种缺陷的位置和形式的可能性。