نتایج جستجو برای: underwater acoustics

تعداد نتایج: 25089  

Journal: :Signal Processing 2017
Soydan Redif Stephan D. Weiss John G. McWhirter

The polynomial matrix EVD (PEVD) is an extension of the conventional eigenvalue decomposition (EVD) to polynomial matrices. The purpose of this article is to provide a review of the theoretical foundations of the PEVD and to highlight practical applications in the area of broadband blind source separation (BSS). Based on basic definitions of polynomial matrix terminology such as parahermitian a...

1997
Michael Papazoglou Jeffrey L. Krolik

The refraction of over-the-horizon skywave radar signals by the ionosphere facilitates wide-area surveillance. While current systems measure target ground range, azimuth, and velocity they do not estimate target altitude, which is important for classi cation purposes. In this paper, a method akin to matchedeld processing in underwater acoustics is proposed for target heightnding. The approach e...

Journal: :The Journal of the Acoustical Society of America 1988
L Halpern L N Trefethen

A one-way wave equation, also known as a paraxial or parabolic wave equation, is a differential equation that permits wave propagation in certain directions only. Such equations are used regularly in underwater acoustics, in geophysics, and as energy-absorbing numerical boundary conditions. The design of a one-way wave equation is connected with the approximation of (1-s2)1/2 on [-1,1] by a rat...

2016
S. Watson S. Viola G. Giuliano S. P. Najda P. Perlin T. Suski L. Marona M. Leszczyński P. Wisniewski R. Czernecki G. Targowski M. A. Watson H. White D. Rowe L. Laycock A. E. Kelly

GaN-based laser diodes have been developed over the last 20 years making them desirable for many security and defence applications, in particular, free space laser communications. Unlike their LED counterparts, laser diodes are not limited by their carrier lifetime which makes them attractive for high speed communication, whether in free space, through fiber or underwater. Gigabit data transmis...

2012
D. Keus

Surface vessels and submarines must be able to defend themselves against a torpedo attack. Several studies have shown the benefits of multi-platform and multi-static operations. To facilitate torpedo defence system studies and the development of future tactics, TNO Defence, Security and Safety started the development of the Underwater Warfare Testbed (UWT). This testbed integrates the simulatio...

2014
Louis-Kiguchi Reed

Real-time cooperation between autonomous vehicles can enable time-critical missions such as tracking and pursuit of a dynamic target or environmental feature, but relies on wireless communications. Underwater, communication over distances beyond about one hundred meters is almost exclusively accomplished through acoustics, which bring challenges such as propagation delays, low data rates, packe...

Journal: :Advanced Functional Materials 2022

Flexible and wearable sensors are highly desired for health monitoring, agriculture, sport, indoor positioning systems applications. However, the currently developed wireless sensors, which communicated through radio signals, can only provide limited accuracy often ineffective in underwater conditions. In this paper, a platform based on flexible piezoelectric acoustics is with multiple function...

Journal: :Geosciences 2021

The west Florida shelf (WFS; Gulf of Mexico, USA) is an important area for commercial and recreational fishing, yet much it remains unmapped unexplored, hindering effective monitoring fish stocks. goals this study were to map the habitat at intensively fished on WFS known as “The Elbow”, assess differences in communities among different types, estimate abundance each taxa within area. High-reso...

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