t-shape profile barriers are one of the most successful barriers among many different profiles. it has been shown that using welled diffusers on the top of t-shaped barriers makes a reactive barrier that shows better performance than that of any other used profile barriers compared with their equivalent absorbent barrier. the contribution of the top surface of reactive t-profile barriers to the...

Solving an acoustic wave equation using a parabolic approximation is popular approach for many existing ocean models. Commonly used (PE) model programs, such as the range-dependent (RAM), are discretized by finite difference method (FDM). Considering idea and theory of wide-angle rational approximation, discrete PE Chebyshev spectral (CSM) derived, code developed. This currently suitable only r...

An inspection of signal processing approach in order to estimate underwater network cardinalities is conducted in this research. A matter of key prominence for underwater network is its cardinality estimation as the number of active cardinalities varies several times due to numerous natural and artificial reasons due to harsh underwater circumstances. So, a proper estimation technique is mandat...

The object of research: the shift resonant frequency piezoceramic electroacoustic transducer Langevin type depending on shape back plate.
 Investigated problem: relationship between changes in plate with oscillating system. Search quantitative contribution to each modifications: shape, diameter, thickness, weight main scientific results: vibration modes a horizontal and vertical radiator r...

Abstract As the dominant information carrier in water, acoustic wave is widely used for underwater detection, communication and imaging. Even though has been greatly improved past decades, it still suffers from slow transmission speeds low capacity. The recently developed orbital angular momentum (OAM) multiplexing promises a high efficiency, large capacity fast speed communication. However, cu...

Underwater robotics is currently a growing field. To be able to autonomously find and collect objects on the land and in the air is a complicated problem, which is only compounded within the underwater setting. Different techniques have been developed over the years to attempt to solve this problem, many of which involve the use of expensive sensors. This paper explores a method to find the dep...

1 Robert O. Lawton Distinguished Professor, Department of Mathematics, Fellow AIAA. 2 Post-Doctoral Research Associate, Department of Mathematics. 3 Research Scientist, Structural Acoustics Branch, Aerodynamics, Aerothermodynamics and Acoustics Competency, Member AIAA. 4 Senior Research Scientist, Computational Modeling and Simulation Branch, Aerodynamics, Aerothermodynamics and Acoustics Compe...

recently, data collection from seabed by means of underwater wireless sensor networks (uwsn) has attracted considerable attention. autonomous underwater vehicles (auvs) are increasingly used as uwsns in underwater missions. events and environmental parameters in underwater regions have a stochastic nature. the target area must be covered by sensors to observe and report events. a ‘topology cont...

Underwater communications mainly rely on acoustic propagation which is strongly affected by frequency-dependent attenuation, shallow water multipath propagation and significant Doppler spread/shift induced by source-receiver-surface motion. Time-reversal based techniques offer a low complexity solution to decrease interferences caused by multipath, but a complete equalization cannot be reached ...