In this paper, a review of several features of the acoustic vector field will be presented. The theoretical foundation for the acoustic energy flow will be used to describe the concepts of the active and reactive components of the complex acoustic intensity field. Recently established phenomenology associated with the flow of acoustic intensity near planar boundaries via the visualization of st...

In this paper we consider Galerkin-finite element methods that approximate the solutions of initial-boundary-value problems in one space dimension for parabolic and Schrödinger evolution equations with dynamical boundary conditions. Error estimates of optimal rates of convergence in L and H are proved for the accociated semidiscrete and fully discrete Crank-Nicolson-Galerkin approximations. The...

In underwater acoustics, the modeling of impulsive noise ambients by symmetric-stable laws is motivated by the generalized central limit theorem. However, detection of stochastic signals under such additive noise is a di cult task to implement, due to the lack of a closed-form expression of the a-posteriori probability density function. In this paper, we present a suboptimal detector for Gaussi...

In this paper, two probabilistic adaptive algorithms for jointly detecting active users in a DS-CDMA system are compared. The rst one, which is based on the theory of Hidden Markov Models (HMM) is proposed within the CDMA scenario and compared with the previously developed Viterbi-based algorithm. Both techniques are completely blind in the sense that no knowledge of the signature sequences, ch...

Transparent boundary conditions (TBCs) for general Schrr odinger{ type equations on a bounded domain can be derived explicitly under the assumption that the given potential V is constant on the exterior of that domain. In 1D these boundary conditions are non{local in time (of memory type). Existing discretizations of these TBCs have accuracy problems and render the overall Crank{Nicolson nite d...

The concept of integrated acoustics for ocean observing embraces passive acoustic monitoring, navigation and positioning, communications, and tomography using fixed and mobile platforms within the framework of unifying, data assimilating ocean and platform models. It has been maturing over the last two decades and longer. Selected results from the authors’ past and present work illustrating the...

We consider the inverse coefficient problem of locating the interface positions arising in frequency sounding of layered media. Such a problem is of particular interest in the exploration of geophysics, underwater acoustics and electromagnetics, optical sensing, and so forth. We found that a simplified algorithm can be constructed to determine the approximate positions of interfaces. Unlike the...

In situ acoustic calibration devices are necessary to assure the optimal performance of sensors and detectors for the acoustic detection of ultra-high energy neutrinos in underwater telescopes. Moreover, they provide evidences for the feasibility evaluation of the technique and for the determination of the entire detector efficiency. Following previous studies related to parametric acoustic sou...

The problem of HOS-based signal detection methods applied in real communication systems is addressed. The Locally Optimum (LO) criterion is selected from a large number of detection criteria. It can be applied either under the ideal (but often not realistic) assumption of Gaussian background noise, or on the basis of realistic statistical models of channel noise. Conventional Fourier analysis (...

As the sand grain size approaches the acoustic wavelength, the underwater backscattering strength increases. Laboratory measurements show that the shallow-grazing angle backscattering strength increases as the third power of the normalized grain diameter, until it reaches a saturation level. In this regime, it has been shown that the attenuation of the sound in the sand increases as the fourth ...