Design and field testing of a non-linear single-beam echosounder for multi-frequency seabed characterization

2022 ◽  
Vol 187 ◽  
pp. 108490
Author(s):  
Irène Mopin ◽  
Jacques Marchal ◽  
Michel Legris ◽  
Gilles Le Chenadec ◽  
Philippe Blondel ◽  
...  
Keyword(s):  
2019 ◽  
Vol 60 ◽  
pp. 154-161
Author(s):  
Raad Sh. Alnayli ◽  
Hanan Alkazaali

In this work we study the influence of the laser pulses silver nanoparticles productivity during laser ablation of silver immersed in liquid. Ag nanoparticles were synthesized by pulsed laser ablation of Ag targets in ethanol using the (1064 nm, Q-switched, Nd:YAG) laser with energy of 140 mJ per pulse. UV-Visible absorption spectra were used for the characterization and comparison of products. The non-linear refractive index and absorption coefficient of silver nanoparticles were investigated using a single beam z-scan technique; the excitation source was a continuous wave (CW) of 650 nm diode laser with a beam power of 50 mW. All investigated samples showed negative-induced non-linear refractive indices.


2010 ◽  
Vol 33 (1) ◽  
pp. 103-106 ◽  
Author(s):  
J. Villarroel ◽  
O. Caballero-Calero ◽  
B. Ramiro ◽  
A. Alcázar ◽  
A. García-Cabañes ◽  
...  

2019 ◽  
Vol 4 (11) ◽  
pp. 74-81
Author(s):  
Anusha Wijesundara ◽  
R. M. D. I. Rathnayake

Coastal bathymetry is the most essential tool for marine planning, monitoring and management, modelling, nautical navigation and scientific studies of marine environments. The techniques have been developed over the last decade to derive bathymetry using remote sensing technology with efficiently and low costly. Log linear bathymetric inversion model and non-linear bathymetric inversion model provides two empirical approaches for deriving bathymetry from multispectral satellite imagery, which have been refined and widely applied. This paper compares these two approaches by means of a geographical error analysis for the site Kankesanturai using WorldView-2 satellite imagery. In order to calibrate both models; Single Beam Echo Sounding (SBES) data in this study area were used as reference points. Corrections for atmospheric and sun-glint effects are applied prior to the water depth algorithm. The algorithm was tuned and both models were calibrated by performing the necessary algorithm with available single beam echo sounding data in the study area. The coefficients of standard R2 is estimated as 0.846 for log-linear and 0.692 for non-linear model. Log linear model performs better than the non-linear model. The model residuals were mapped and the spatial auto-correlation was calculated based on the bathymetric estimation model. A spatial error model was constructed to generate more reliable estimates of bathymetry by calculating the spatial autocorrelation of model error and integrating this into an improved regression model.  Finally, the spatial error model improved the bathymetric estimates of R2 up to 0.854 for log-linear and 0.704 non-linear model respectively. The Root Mean Square Error (RMSE) was calculated for the different depth ranges and also for all reference points. The overall accuracy for the log linear and the non-linear inversion model after the geographical error analysis is estimated as ±1.532 m and ±2.089 m for this study. The spatial error model improved bathymetric estimates than those derived from a conventional log-linear and non-linear technique although these methods perform very similar estimates overall.


1967 ◽  
Vol 28 ◽  
pp. 105-176
Author(s):  
Robert F. Christy

(Ed. note: The custom in these Symposia has been to have a summary-introductory presentation which lasts about 1 to 1.5 hours, during which discussion from the floor is minor and usually directed at technical clarification. The remainder of the session is then devoted to discussion of the whole subject, oriented around the summary-introduction. The preceding session, I-A, at Nice, followed this pattern. Christy suggested that we might experiment in his presentation with a much more informal approach, allowing considerable discussion of the points raised in the summary-introduction during its presentation, with perhaps the entire morning spent in this way, reserving the afternoon session for discussion only. At Varenna, in the Fourth Symposium, several of the summaryintroductory papers presented from the astronomical viewpoint had been so full of concepts unfamiliar to a number of the aerodynamicists-physicists present, that a major part of the following discussion session had been devoted to simply clarifying concepts and then repeating a considerable amount of what had been summarized. So, always looking for alternatives which help to increase the understanding between the different disciplines by introducing clarification of concept as expeditiously as possible, we tried Christy's suggestion. Thus you will find the pattern of the following different from that in session I-A. I am much indebted to Christy for extensive collaboration in editing the resulting combined presentation and discussion. As always, however, I have taken upon myself the responsibility for the final editing, and so all shortcomings are on my head.)


Optimization ◽  
1975 ◽  
Vol 6 (4) ◽  
pp. 549-559
Author(s):  
L. Gerencsér

1979 ◽  
Author(s):  
George W. Howe ◽  
James H. Dalton ◽  
Maurice J. Elias
Keyword(s):  

2007 ◽  
Author(s):  
David E. Kancler ◽  
Christopher C. Curtis ◽  
Darryl S. Stimson ◽  
Johnnie Jernigan

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