Patents by Inventor Nai-Hsien Mao

Nai-Hsien Mao has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Shear wave transducer for stress measurements in boreholes
    Patent number: 4641520
    Abstract: A technique and apparatus for estimating in situ stresses by measuring stress-induced velocity anisotropy around a borehole. Two sets each of radially and tangentially polarized transducers are placed inside the hole with displacement directions either parallel or perpendicular to the principal stress directions. With this configuration, relative travel times are measured by both a pulsed phase-locked loop technique and a cross correlation of digitized waveforms. The biaxial velocity data is used to back-calculate the applied stress.
    Type: Grant
    Filed: August 23, 1984
    Date of Patent: February 10, 1987
    Assignee: The United States of America as represented by the United States Department of Energy
    Inventor: Nai-Hsien Mao