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large-amplitude-oscillation
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Buzz cycle description in an axisymmetric mixed-compression air intake
, Article AIAA Journal ; Volume 54, Issue 3 , 2016 , Pages 1036-1049 ; 00011452 (ISSN) ; Sepahi Younsi, J ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2016
Abstract
Buzz phenomenon is shock oscillation ahead of the supersonic air intake when its mass flow rate is decreasing at offdesign condition. The buzz onset and the buzz cycle of an axisymmetric mixed-compression supersonic intake have been experimentally investigated through pressure recording and shadowgraph flow visualization. The intake was designed for a freestream Mach number of 2.0; however, tests were conducted for M∞ = 1.8, 2.0, and 2.2. All tests were performed at 0 deg angle of attack. Results show that there is a strong relation between the acoustic characteristics of the intake and the buzz fluctuations. This relation causes a new pattern for the buzz oscillations, large-amplitude...
Finite time-Lyapunov based approach for robust adaptive control of wind-induced oscillations in power transmission lines
, Article Journal of Sound and Vibration ; Volume 371 , 2016 , Pages 19-34 ; 0022460X (ISSN) ; Moradi, H ; Vossoughi, G ; Sharif University of Technology
Academic Press
2016
Abstract
Large amplitude oscillation of the power transmission lines, which is also known as galloping phenomenon, has hazardous consequences such as short circuiting and failure of transmission line. In this article, to suppress the undesirable vibrations of the transmission lines, first the governing equations of transmission line are derived via mode summation technique. Then, due to the occurrence of large amplitude vibrations, nonlinear quadratic and cubic terms are included in the derived linear equations. To suppress the vibrations, arbitrary number of the piezoelectric actuators is assumed to exert the actuation forces. Afterwards, a Lyapunov based approach is proposed for the robust adaptive...