the present study utilizes an analytical method to formulate the three lowest modal frequencies of axially-loaded notched beam through both crack location and load level in a specific format that can be used in existing frequency-based crack-identification methods. the proposed formula provides a basis to shift into two states, one with axial loading and the other without any loading whatsoever...

We present simulations results and experimental evidence of radiation energy extraction e$ciency enhancement by use of pre-bunching in a free electron maser (FEM). This enhancement is attained by locking the oscillator to operate at a distinct resonator eigen frequency (longitudinal mode) which is di!erent from the maximum-gain frequency of the free running oscillator. The mode selection is acc...

It is suggested that the accretion disk excites the eigen modes of Alfven oscillations of the magnetic field tubes the ends of which are frozen to the neutron star surface. The resonance takes place when the eigen Alfven frequency coincides with the difference of the Keplerian disk rotation frequency and the frequency of rotation of a neutron star. This model explains the two narrow lines of QP...

In this Paper, a novel approach based on Cuckoo search optimization, with dominant eigen value shift for designing robust decentralized load frequency control system for interconnected power system is presented. A proportional integral – derivative (PID) controller is considered to exemplify the optimum parameter search. To demonstrate the robustness of the obtained controller, a two-area non r...

This paper presents an improved scheme to compensate nonlinear phase path contamination when the backscattered signal propagates through the ionosphere in high-frequency skywave radar systems. The ionospheric variation often causes the spread of the ocean clutter spectrum in the frequency domain. The energy of the first-order component of ocean clutter dominates in Doppler spectrum, and thus it...

Fractional Fourier transform (FRFT) is a generalization of Fourier transform, and it indicates a rotation of signal in the time-frequency plane[l). The FRFT has been widely successfully used in the many areas[l][2]. Because of the importance of FRFT, discrete fractional Fourier transform (DFRFT) becomes an important issue in recent years[3][4] [5][6]. In the development of DFRFT, the DFRFT has ...