發送短信 : On propagation characteristics of ultrasonic guided waves in helical strands

            ______    ______    ______  __    __  
    ___    /_   _//  /_____//  /_   _// \ \\ / // 
   /   ||   -| ||-   `____ `    -| ||-   \ \/ //  
  | [] ||   _| ||_   /___//     _| ||_    \  //   
   \__ ||  /_____//  `__ `     /_____//    \//    
    -|_||  `-----`   /_//      `-----`      `     
     `-`             `-`