scholarly journals High‐frequency forward scattering from Gaussian spectrum, pressure release, corrugated surfaces: Measurements of twinkling exponents and the dependence of the second moment on distance from surface and pulse length

1994 ◽  
Vol 96 (5) ◽  
pp. 3231-3231
Author(s):  
J. S. Stroud ◽  
P. L. Marston ◽  
K. L. Williams
Keyword(s):  
High Frequency ◽  
Pulse Length ◽  
Forward Scattering ◽  
Second Moment ◽  
Pressure Release ◽  
Corrugated Surfaces ◽  
Gaussian Spectrum

HIGH FREQUENCY PERCUSSIVE VENTILATION CAN MIMIC AIRWAY PRESSURE RELEASE VENTILATION IN A TEST LUNG MODEL

2004 ◽  
Vol 32 (Supplement) ◽  
pp. A38
Author(s):  
Faera L Byerly ◽  
Bruce A Cairns ◽  
Kathy A Short ◽  
John A Haithcock ◽  
Lynn Shapiro ◽  
...  
Keyword(s):  
High Frequency ◽  
Airway Pressure ◽  
Airway Pressure Release Ventilation ◽  
Lung Model ◽  
Test Lung ◽  
Pressure Release ◽  
Pressure Release Ventilation

Experimental demonstration of a high-frequency forward scattering acoustic barrier in a dynamic coastal environment

2010 ◽  
Vol 127 (6) ◽  
pp. 3430-3439 ◽  
Author(s):  
Karim G. Sabra ◽  
Stephane Conti ◽  
Philippe Roux ◽  
Tuncay Akal ◽  
William A. Kuperman ◽  
...  
Keyword(s):  
High Frequency ◽  
Coastal Environment ◽  
Forward Scattering ◽  
Experimental Demonstration

Kirchhoff Approximations for the Forward-Scattering Target Strength of Underwater Objects

2019 ◽  
Vol 28 (01) ◽  
pp. 1950008
Author(s):  
Chuanlin He ◽  
Yi Zheng ◽  
Xu Xiang ◽  
Yuanliang Ma
Keyword(s):  
High Frequency ◽  
Mode Coupling ◽  
Forward Scattering ◽  
Target Strength ◽  
Kirchhoff Approximation ◽  
Prolate Spheroids ◽  
Cylinder Method ◽  
Kirchhoff Integral ◽  
Numerical Approaches ◽  
Acoustic Approximation

Kirchhoff approximations for the forward-scattering target strength of underwater objects are developed by combining Babinet’s principle and the Kirchhoff integral, where theoretical formulations and a numerical implementation are given in detail. The Kirchhoff approximation is found to be a high-frequency physical acoustic approximation. The forward-scattering target strength versus frequency and the spatial angles for spherical objects, prolate spheroids and the Benchmark Target Strength Simulation Submarine (BeTSSi-Sub) model are obtained by the Kirchhoff approximation and compared with results from theory, the deformed cylinder method (DCM) and the boundary element method (BEM). The Kirchhoff approximation shows considerable agreement with the theoretical and numerical approaches in a region of [Formula: see text] from the rigorous forward-scattering direction. The forward-scattered field contour and the corresponding directivity for the BeTSSi-Sub model are also calculated as a demonstration. Mode coupling caused by the simulated target is clearly revealed. The results indicate that the Kirchhoff approximation can predict the forward-scattering target strength of complex underwater objects.

scholarly journals The Use of the Reassignment Technique in the Time-Frequency Analysis Applied in VHF-Based Passive Forward Scattering Radar

Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3434
Author(s):  
Marek Płotka ◽  
Karol Abratkiewicz ◽  
Mateusz Malanowski ◽  
Piotr Samczyński ◽  
Krzysztof Kulpa
Keyword(s):  
High Frequency ◽  
Real Life ◽  
Forward Scattering ◽  
Kinematic Parameters ◽  
Very High Frequency ◽  
Digital Video Broadcasting ◽  
Time Frequency ◽  
Video Broadcasting ◽  
Airborne Target ◽  
Very High

This paper presents the application of the time-frequency (TF) reassignment technique in passive forward scattering radar (FSR) using Digital Video Broadcasting – Terrestrial (DVB-T) transmitters of opportunity operating in the Very High Frequency (VHF) band. The validation of the proposed technique was done using real-life signals collected by the passive radar demonstrator during a measurement campaign. The scenario was chosen to test detection ranges and the capability of estimating the kinematic parameters of a cooperative airborne target in passive FSR geometry. Additionally, in the experiment the possibility of utilizing FSR geometry in foliage penetration conditions taking advantage of the VHF band of a DVB-T illuminator of opportunity was tested. The results presented in this paper show that the concentrated (reassigned) energy distribution of the signal in the TF domain allows a more precise target Doppler rate to be estimated using the Hough transform.

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