Performance of a high‐frequency acoustic forward‐scatter barrier in a dynamic coastal environment

2007 ◽  
Vol 121 (5) ◽  
pp. 3085-3086
Author(s):  
Karim G. Sabra ◽  
Stephane Conti ◽  
Philippe Roux ◽  
W. A. Kuperman ◽  
J. Mark Stevenson ◽  
...  
Keyword(s):  
High Frequency ◽  
Coastal Environment ◽  
Forward Scatter

Modern and Holocene microbial mats and associated microbially induced sedimentary structures (MISS) on the southeastern coast of Tunisia (Mediterranean Sea)

2020 ◽  
pp. 1-21
Author(s):  
Rached Lakhdar ◽  
Mohamed Soussi ◽  
Rachida Talbi
Keyword(s):  
Spatial Distribution ◽  
High Frequency ◽  
Depositional Environment ◽  
Microbial Mats ◽  
Coastal Environment ◽  
Tidal Dynamics ◽  
Very High Frequency ◽  
Intertidal Zones ◽  
Sedimentary Structures ◽  
Very High

Abstract On the southeastern Tunisian coastline, very diverse living microbial mats colonize the lower supratidal and intertidal zones, and locally may extend into the upper infratidal zone. The interaction between the benthic cyanobacteria and their siliciclastic substratum leads to the development of several types of microbially induced sedimentary structures (MISS). The mapping of the microbial mats has allowed the identification of the types of MISS that characterize the different segments of the coastal environment. The modern microbial mats have been compared with those recorded at the top of the Holocene deposits, which are composed of biodegraded microbial black mats alternating with white laminae made of clastic and evaporitic sediments, indicative of very high frequency cycles of flood and drought. A hypothetic profile showing their occurrences along the different areas bordering the coastline is proposed as a guide for the reconstruction of the ancient depositional environment. The roles of tidal dynamics, storms, and climate in controlling their genesis and spatial distribution, are discussed and highlighted. The modern MISS of southeastern Tunisia are compared with their equivalents that are well documented through the different geological eras.

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

A Disturbing Factor in Very High Frequency Communications Via Ionospheric Forward Scatter

Nature ◽  
1956 ◽  
Vol 178 (4545) ◽  
pp. 1280-1283 ◽  
Author(s):  
D. A. CROW ◽  
F. A. KITCHEN ◽  
G. A. ISTED ◽  
G. MILLINGTON
Keyword(s):  
High Frequency ◽  
Very High Frequency ◽  
Disturbing Factor ◽  
Forward Scatter ◽  
Very High

High‐frequency forward scatter and propagation experiments in the Delaware Bay

1998 ◽  
Vol 104 (3) ◽  
pp. 1748-1748
Author(s):  
Wenkai Qin ◽  
Mohsen Badiey ◽  
Randy Zagar ◽  
Jeff Simmen
Keyword(s):  
High Frequency ◽  
Delaware Bay ◽  
Forward Scatter

scholarly journals Clutter Distribution Analysis of A Tropical Foliage Clutter for Different Profiles Based on FSR Micro-Sensor Network

2018 ◽  
Vol 7 (3.7) ◽  
pp. 72
Author(s):  
Nur Alia Zulkifli ◽  
N E. Abd Rashid ◽  
Z I. Khan ◽  
N N. Ismail ◽  
R S. A. Raja Abdullah ◽  
...  
Keyword(s):  
High Frequency ◽  
Free Space ◽  
Distribution Model ◽  
Distribution Analysis ◽  
Distribution Models ◽  
Very High Frequency ◽  
Forward Scatter ◽  
Micro Sensor ◽  
Log Normal ◽  
Very High

Comparison of four different clutter profiles (border, seaside, free space and forest) using Forward Scatter Radar (FSR), which operates in Ultra-High and Very High Frequency (UHF and VHF) bands, is analyzed in this paper. Clutter levels ranging from low, medium, strong and very strong on each profile were studied. Based on the standard deviation of each clutter profile, border suits the best profile as the strongest clutter profile amidst seaside and free space, while the forest is determined as the lowest clutter profile. Subsequently, the characteristics of the clutter are investigated and compared based on the five distribution models (Log-Normal, Log-Logistic, Gamma, Weibull and Nakagami).  The parameters of the five distributions are evaluated using Root Mean Square Error (RMSE) in order to prove that the distribution model fits best to the clutter data. It can be concluded that Gamma distribution is the best distribution model for all cases of frequency bands and profiles.  

STATISTICAL ANALYSIS FOR TERENGGANU FORWARD SCATTER RADAR SEASIDE CLUTTER

2016 ◽  
Vol 78 (5-7) ◽  
Author(s):  
Nor Najwa Ismail ◽  
Nur Emileen Abd Rashid ◽  
Zuhani Ismail Khan
Keyword(s):  
Statistical Analysis ◽  
Weibull Distribution ◽  
High Frequency ◽  
Goodness Of Fit ◽  
Distribution Model ◽  
Logistic Distribution ◽  
Distribution Models ◽  
Very High Frequency ◽  
Forward Scatter ◽  
Scatter Radar

The statistical analysis for Terengganu, Malaysia seaside clutter is presented in this paper. The measured clutter data were collected using a prototype of forward scatter radar (FSR) micro-sensor network with very high frequency (VHF) and ultra-high frequency (UHF) bands. Four categories of clutter strength were recorded during the measurements, which are low, medium, strong and very strong clutter. The classes were divided according to the wind speed occurred during the measurements period. The analysis is to determine the best-fit distribution model for the measured clutter data. Four types of distribution models are used in this analysis, which are Weibull, Gamma, Log-Logistic and Log-Normal distribution. One of the goodness of fit (GOF) tests called root mean square error (RMSE) is used to prove which distribution is a better fit to the probability distribution of the measured clutter data. The obtained results show that for 64 MHz with all clutter level strength, Weibull distribution provides better fit and records the lowest RMSE. Weibull distribution also fits best to the clutter data for low clutter of 151 MHz. However, for the rest of clutter level strength for 151 MHz, Gamma distribution is the best-fitted model with lowest RMSE values. Log-Logistic distribution proves to be the best fitted model to all clutter level strength of clutter data for 434 MHz with smallest RMSE values.

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