【机 构】
:
DepartmentofEngineeringPhysics&CenterforAstrophysics,DepartmentofPhysics&CenterforAstrophysics,KeyLa
【基金项目】
:
Supported by the National Natural Science Foundation of China.Acknowledgements We thank the anonymous referee of our previous publication (Feng et ai. 2004), whose comments on the HHT method motivated