The Experts below are selected from a list of 22215 Experts worldwide ranked by ideXlab platform
L Bartolini - One of the best experts on this subject based on the ideXlab platform.
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experimental evidence of signal Optical noise interferencelike effect in underwater amplitude modulated laser Optical Radar systems
Optics Letters, 2008Co-Authors: L Bartolini, L De Dominicis, Ferri M De Collibus, G Fornetti, M Francucci, M Guarneri, Marcello Nuvoli, E Paglia, R RicciAbstract:We report experimental evidence that in an amplitude-modulated laser Optical Radar system for underwater 3D imaging the observed contrast oscillations as a function of the modulation frequency originate from an interferencelike effect between target signal VT and water backscattered radiation VW. The demonstration relies on the ability to perform a direct measurement of VW in a 25 m long test tank. The proposed data processing method enables one to remove the contribution of water backscattering from the detected signal and drastically reduce signal fluctuations due to the medium. Experiments also confirm the possibility to improve the signal to Optical noise ratio and contrast by increasing the modulation frequency.
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advanced digital processing for amplitude and range determination in Optical Radar systems fusion reactor inspection
IEEE Transactions on Nuclear Science, 2002Co-Authors: C Neri, L Bartolini, G Fornetti, A Coletti, M F De Collibus, S Lupini, F Pollastrone, L Semeraro, C TalaricoAbstract:An amplitude modulated laser Radar has been developed by the Italian Agency for New Technologies, Energy and the Environment (ENEA) for periodic in-vessel inspection in large fusion machines. The viewing system is based on a transceiving Optical Radar using a radio frequency (RF) modulated single-mode 840-nm wavelength laser beam. The sounding beam is transmitted through a coherent Optical fiber to a probe, on the tip of which a focusing optics and suitable scanning system, using a silica prism, steers the laser beam in order to obtain a complete 3-D mapping of the in-vessel surface. This paper describes the digital signal processing system used to modulate the laser beam, as well as to measure both the amplitude of the backscattered laser beam and the phase difference between it and the modulation signal. This information, together with the information on the scanning system position, are acquired and then used by the visualization system to produce both 2-D and 3-D images. The system is based on VME boards and directly acquires and processes in real-time three 79.5-MHz RF signals by using a digital receiver and four digital signal processors. The system principles, the mathematical algorithm, and the system architecture are described hereafter.
G Fornetti - One of the best experts on this subject based on the ideXlab platform.
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experimental evidence of signal Optical noise interferencelike effect in underwater amplitude modulated laser Optical Radar systems
Optics Letters, 2008Co-Authors: L Bartolini, L De Dominicis, Ferri M De Collibus, G Fornetti, M Francucci, M Guarneri, Marcello Nuvoli, E Paglia, R RicciAbstract:We report experimental evidence that in an amplitude-modulated laser Optical Radar system for underwater 3D imaging the observed contrast oscillations as a function of the modulation frequency originate from an interferencelike effect between target signal VT and water backscattered radiation VW. The demonstration relies on the ability to perform a direct measurement of VW in a 25 m long test tank. The proposed data processing method enables one to remove the contribution of water backscattering from the detected signal and drastically reduce signal fluctuations due to the medium. Experiments also confirm the possibility to improve the signal to Optical noise ratio and contrast by increasing the modulation frequency.
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advanced digital processing for amplitude and range determination in Optical Radar systems fusion reactor inspection
IEEE Transactions on Nuclear Science, 2002Co-Authors: C Neri, L Bartolini, G Fornetti, A Coletti, M F De Collibus, S Lupini, F Pollastrone, L Semeraro, C TalaricoAbstract:An amplitude modulated laser Radar has been developed by the Italian Agency for New Technologies, Energy and the Environment (ENEA) for periodic in-vessel inspection in large fusion machines. The viewing system is based on a transceiving Optical Radar using a radio frequency (RF) modulated single-mode 840-nm wavelength laser beam. The sounding beam is transmitted through a coherent Optical fiber to a probe, on the tip of which a focusing optics and suitable scanning system, using a silica prism, steers the laser beam in order to obtain a complete 3-D mapping of the in-vessel surface. This paper describes the digital signal processing system used to modulate the laser beam, as well as to measure both the amplitude of the backscattered laser beam and the phase difference between it and the modulation signal. This information, together with the information on the scanning system position, are acquired and then used by the visualization system to produce both 2-D and 3-D images. The system is based on VME boards and directly acquires and processes in real-time three 79.5-MHz RF signals by using a digital receiver and four digital signal processors. The system principles, the mathematical algorithm, and the system architecture are described hereafter.
C O Justice - One of the best experts on this subject based on the ideXlab platform.
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wetland mapping in the congo basin using Optical and Radar remotely sensed data and derived topographical indices
Remote Sensing of Environment, 2010Co-Authors: Jeanrobert B Bwangoy, Matthew C Hansen, Gianfranco De Grandi, C O JusticeAbstract:article i nfo This study reports results of a classification tree approach to mapping the wetlands of the Congo Basin, focusing on the Cuvette Centrale of the Congo River watershed, an area of 1,176,000 km 2 . Regional expert knowledge was used to train passive Optical remotely sensed imagery of the Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) sensors, JERS-1 active Radar L-band imagery, and topographical indices derived from 3 arc sec elevation data of the Shuttle Radar Topography Mission (SRTM). All data inputs were resampled to a common 57 m resolution grid. A classification tree bagging procedure was employed to produce a final map of per-grid cell wetland probability. Thirty bagged trees were ranked and the median result was selected to produce the final wetland probability map. Thresholding the probability map at < 0.5 yielded a proportion of wetland cover for the study area of 32%, equivalent to 360,000 km 2 . Wetlands predominate in the CARPE Lake Tele-Lake Tumba landscape located in the western part of the Democratic Republic of the Congo and the south-eastern Republic of Congo, where they constitute 56% of the landscape. Local topography depicting relative elevation for sub-catchments proved to be the most valuable discriminator of wetland cover. However, all sources of information (i.e. Optical, Radar and topography) featured prominently in contributing to the classification tree procedure, reinforcing the idea that multi-source data are useful in the characterization of wetland land cover. The method employed freely available data and a fully automated process, except for training data collection. Comparisons to existing maps and in situ field observations indicate improvements compared to previous efforts.
R Ricci - One of the best experts on this subject based on the ideXlab platform.
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experimental evidence of signal Optical noise interferencelike effect in underwater amplitude modulated laser Optical Radar systems
Optics Letters, 2008Co-Authors: L Bartolini, L De Dominicis, Ferri M De Collibus, G Fornetti, M Francucci, M Guarneri, Marcello Nuvoli, E Paglia, R RicciAbstract:We report experimental evidence that in an amplitude-modulated laser Optical Radar system for underwater 3D imaging the observed contrast oscillations as a function of the modulation frequency originate from an interferencelike effect between target signal VT and water backscattered radiation VW. The demonstration relies on the ability to perform a direct measurement of VW in a 25 m long test tank. The proposed data processing method enables one to remove the contribution of water backscattering from the detected signal and drastically reduce signal fluctuations due to the medium. Experiments also confirm the possibility to improve the signal to Optical noise ratio and contrast by increasing the modulation frequency.
Gabriela Banon - One of the best experts on this subject based on the ideXlab platform.
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A review on crocodilian nesting habitats and their characterisation via remote sensing:supplementary material
2019Co-Authors: Boris Marioni, Francisco Villamarín, Eduardo M. Arraut, Gabriel M. Moulatlet, Gabriela Banon, Camilo Rennó, Evlyn NovoAbstract:Crocodilians usually remain inside or near their nests during most vulnerable life stages (as eggs, neonates and reproductive females). Thus, protection of nesting sites is one of the most appropriate conservation actions for these species. Nesting sites are often found across areas with difficult access, making remote sensing a valuable tool used to derive environmental variables for characterisation of nesting habitats. In this study, we (i) review crocodilian nesting habitats worldwide to identify key variables for nesting site distribution: proximity to open-water, open-water stability, vegetation, light, precipitation, salinity, soil properties, temperature, topography, and flooding status, (ii) present a summary of the relative importance of these variables for each crocodilian species, (iii) identify knowledge gaps in the use of remote sensing methods currently used to map potential crocodilian nesting sites, and (iv) provide insight into how these remotely sensed variables can be derived to promote research on crocodilian ecology and conservation. We show that few studies have used remote sensing and that the range of images and methods used comprises a tiny fraction of what is available at little to no cost. Finally, we discuss how the combined use of remote sensing methods – Optical, Radar, and laser – may help overcome difficulties routinely faced in nest mapping (e.g., cloud cover, flooding beneath the forest canopy, or complicated relief) in a relevant way to crocodilians and to other semiaquatic vertebrates in different environments.