Linear field perturbations of a black hole are described by the Green function of the wave equation that they obey. After Fourier decomposing the Green function, its two natural contributions are given by poles (quasinormal modes) and a largely unexplored branch cut in the complex frequency plane. We present new analytic methods for calculating the branch cut on a Schwarzschild black hole for a...

Thermal instability in a horizontal Newtonian liquid layer with rigid boundaries is investigated in the presence of vertical quasiperiodic forcing having two incommensurate frequencies omega1 and omega2. By means of a Galerkin projection truncated to the first order, the governing linear system corresponding to the onset of convection is reduced to a damped quasiperiodic Mathieu equation. The t...

We compute the quasinormal frequencies of $d$-dimensional spherically symmetric black holes with leading string $\alpha'$ corrections for tensorial gravitational perturbations in highly damped regime. solve perturbatively master differential equation and we monodromies perturbation variable (analytically continued to complex plane) different contours, order obtain mode spectra. proceed analogou...

Flame sheet problems are on the natural route to the numerical solution of detailed chemistry, laminar di usion ames, which, in turn, are important in many engineering applications. In order to model the ame structure more accurately, we use the vorticity-velocity formulation of the uid ow equations instead of the more traditional stream function-vorticity approach. The numerical solution of th...

Humans can discriminate among the hardness of objects by tapping their surfaces. The damped natural vibration caused by tapping and its frequency are known to be the cue for the perception of hardness. This study is an investigation of the characteristics of this perception of hardness, as induced by vibration stimuli including multiple frequency components. We performed a comparative experimen...

It is vital to improve the stability of power system by accurately identifying modal parameters damped low-frequency oscillations (DLFO) and controlling oscillation in time. A new method based on empirical mode decomposition (EMD), stochastic subspace identification (SSI), Prony algorithms, called synthetical (SMPI) method, developed efficiently matching DLFO which are acquired from SSI algorit...

In this paper non-synchronous vibration (NSV) of a GE axial compressor is simulated using a fully coupled fluid/strcuture interaction (FSI). Time accurate NavierStokes equations are solved with a system of 5 decoupled structure modal equations in a fully coupled manner. A 3rd order WENO scheme for the inviscid flux and a 2nd order central differencing for the viscous terms are used to resolve n...

We compute the quasinormal frequencies of d-dimensional large spherically symmetric black holes with Gauss-Bonnet corrections in highly damped regime. solve perturbatively master differential equation and we monodromies perturbation variable (analytically continued to complex plane) different contours, order obtain mode spectra. consider tensorial, vectorial scalar gravitational perturbations, ...

this study introduces the differential transform method (dtm) to analyse the free vibration response of a rotating, closed section, composite, timoshenko beam which features material coupling between flapwise bending and torsional vibrations due to ply orientation. the governing differential equations of motion are derived using hamilton’s principle and solved by applying dtm. the natural frequ...

We obtain an analytic expression for the highly damped asymptotic quasinormal mode frequencies of the d ≥ 5-dimensional Schwarzschild black hole modified by the GaussBonnet term, which appears in string derived models of gravity. The analytic expression is obtained under the string inspired assumption that there exists a mimimum length scale in the system and in the limit when the coupling in f...