American Journal of Physics and Applications

Volume 8, Issue 2, March 2020

  • Reciprocity Calibration of Hydrophones in High Intensity Focused Ultrasound Field

    Longyang Jia, Wende Shou, Bing Hu

    Issue: Volume 8, Issue 2, March 2020
    Pages: 19-24
    Received: 26 March 2020
    Accepted: 22 April 2020
    Published: 11 May 2020
    Abstract: The primary problem of safety and efficiency for the high intensity therapeutic ultrasound (HITU) is the acoustic measure and dose control. The key technique is the pressure and intensity in the acoustic field especial in the focal region using the small calibrated hydrophone. The calibration accuracy of the used hydrophone is very important for HI... Show More
  • Description of the Motion of Objects with Sub- and Superluminal Speeds

    Janusz Wolny, Radoslaw Strzalka

    Issue: Volume 8, Issue 2, March 2020
    Pages: 25-28
    Received: 20 April 2020
    Accepted: 7 May 2020
    Published: 4 June 2020
    Abstract: In this paper a direct derivation of the dynamics of objects moving with relativistic speeds is presented, based on two assumptions: (i) energy and mass of an object in motion are equivalent (mass-energy equivalence, known in special relativity and confirmed in experiments), (ii) an object can be considered as a variable-mass object with mass incre... Show More