Fausto Milinazzo - Academia.edu (original) (raw)

Uploads

Papers by Fausto Milinazzo

Journal of Fluid Mechanics, 2022

We significantly extend the results of Miles & Sneyd (J. Fluid Mech., vol. 497, 2003, pp. 435–439... more We significantly extend the results of Miles & Sneyd (J. Fluid Mech., vol. 497, 2003, pp. 435–439) for an accelerating line load on a floating ice plate in their simple linear mathematical model by proceeding to numerical calculations for the response due to a decelerating load. Our results show: (i) how the deflections produced by an impulsively started steadily moving line load begin to develop and eventually approach the well-known steady load-speed-dependent quasi-static and wave-like forms, including above the shallow water gravity wave speed where the shadow zone evolves; (ii) the singularity in the deflection predicted in the simple linear model when the load moves steadily is indeed avoided by a uniformly accelerating load, where the magnitude of the deflection continually increases and its maximum lags a little further behind as the load moves through the critical speed and beyond; (iii) there is also no singularity in the deflection due to a uniformly decelerating load, bu...

East Asian Journal on Applied Mathematics, 2012

An infinite Bernoulli-Euler beam (representing the "combined rail" consisting of the rail and lon... more An infinite Bernoulli-Euler beam (representing the "combined rail" consisting of the rail and longitudinal sleeper) mounted on periodic flexible point supports (representing the railpads) has already proven to be a suitable mathematical model for the floating ladder track (FLT), to define its natural vibrations and its forced response due to a moving load. Adopting deliberately conservative parameters for the existing FLT design, we present further results for the response to a steadily (uniformly) moving load when the periodic supports are assumed to be elastic, and then introduce the mass and viscous damping of the periodic supports. Typical support damping significantly moderates the resulting steady deflexion at any load speed, and in particular substantially reduces the magnitude of the resonant response at the critical speed. The linear mathematical analysis is then extended to include the inertia of the load that otherwise moves uniformly along the beam, generating overstability at supercritical speeds-i.e. at load speeds notably above the critical speed predicted for the resonant response when the load inertia is neglected. Neither the resonance nor the overstability should prevent the safe implementation of the FLT design in modern high speed rail systems.

Ocean Engineering, 1987

An efficient algorithm is presented which simulates the three-dimensional motion of a towed cable... more An efficient algorithm is presented which simulates the three-dimensional motion of a towed cable. The formulation is based on an implicit, second-order finite difference approximation of the equations of motion. The results of the computation are compared both to those obtained by another numerical model and to experimental measurements.

The Journal of the Acoustical Society of America, 1997

In this article, stable Padé approximations to the function ͱ1ϩz are derived by choosing a branch... more In this article, stable Padé approximations to the function ͱ1ϩz are derived by choosing a branch cut in the negative half-plane. The Padé coefficients are complex and may be derived analytically to arbitrary order from the corresponding real coefficients associated with the principal branch defined by zϽϪ1, I(z)ϭ0 ͓I(z) denotes the imaginary part of z͔. The characteristics of the corresponding square-root approximation are illustrated for various segments of the complex plane. In particular, for waveguide problems it is shown that an increasingly accurate representation may be obtained of both the evanescent part of the mode spectrum for the acoustic case and the complex mode spectrum for the elastic case. An elastic parabolic equation algorithm is used to illustrate the application of the new Padé approximations to a realistic ocean environment, including elasticity in the ocean bottom.

IEEE Transactions on Speech and Audio Processing, 1993

The estimation of formant frequencies and bandwidths from the filter coefficients obtained throug... more The estimation of formant frequencies and bandwidths from the filter coefficients obtained through LPC analysis of speech is discussed from several viewpoints. A new method for locating roots within the unit circle is derived. This algorithm is particularly well suited to computations carried out in fixed point arithmetic using specialized signal processing hardware.

The Journal of the Acoustical Society of America, 1988

UU4. Matched-field processing and the effect of realistic noise correlation models. Cedric A. Zal... more UU4. Matched-field processing and the effect of realistic noise correlation models. Cedric A. Zala (Barrodale Computing Services,

Mathematical Methods in the Applied Sciences, 2007

ABSTRACT

IEEE Transactions on Acoustics, Speech, and Signal Processing, 1987

When analyzing linear systems of equations, the most important indicator of potential instability... more When analyzing linear systems of equations, the most important indicator of potential instability is the condition number of the matrix. For a convolution matrix W formed from a series w (where Wij wi-, + ,, 1 5 ij + 1 5 k, W,j = 0 otherwise), this condition number defines the stabirity of the deconvolution process. For the larger convolution matrices commonly encountered in practice, direct computation of the condition number (e.g., by singular value decomposition) would be extremely time consuming. However, for convolution matrices, an upper bound for the condition number is defined by the ratio of the maximum to the minimum values of the amplitude spectrum of w. This bound is infinite for any series w with a zero value in its amplitude spectrum; although for certain such series, the actual condition number for W may in fact be relatively small. In this paper we give a new simple derivation of the upper bound and present a means of defining the rate of growth of the condition number of W for a bandlimited series by means of the higher order derivatives of the amplitude spectrum of w at its zeros. The rate of growth is shown to be proportional to m p , where m is the column dimension of Wand p is the order of the zero of the amplitude spectrum.

J Colloid Interface Sci, 1988