Transformation Ray Method: Controlling High Frequency Elastic Waves
  A transformation method based on elastic ray theory is proposed to control high frequency elastic waves. We show that ray path can be controlled in an exact manner, however energy distribution along the ray is only approximately controlled. A numerical example of an elastic rotator is provided to illustrate the method and to access the approximation. The proposed theory may be found potential applications in seismic wave protection and structure health monitoring. 
Zheng Chang, Jin Hu, Xiaoning Liu and Gengkai Hu
physics.class-ph physics.optics