Europe Oceans 2005最新文献

{"title":"Sound fields focused by a biconcave acoustic lens for normal and oblique incidence","authors":"T. Nakamura, M. Hashimoto, K. Mori, T. Kamakura, T. Anada","doi":"10.1109/OCEANSE.2005.1511685","DOIUrl":"https://doi.org/10.1109/OCEANSE.2005.1511685","url":null,"abstract":"In this report, a sound pressure field focused by a biconcave lens was investigated using the wave theory and the numerical methods of the parabolic equation (PE) method and finite difference time domain (FDTD) method for normal incidence. For oblique incidence, the hybrid method which combines ray theory and wave theory was used in the calculation. The experimental data were compared with the theoretical results shown above. The experimental on-axis characteristics around the focal point agreed well with the calculated results but disagreed with the results for in front and behind the focal region. It was found that the second peak existed behind the focal point for normal incidence, though there is no second peak in the theoretical results by the analytical method and the FDTD method. After the numerical analysis by the hybrid method and the PE method, the second peak was found at the same position as the experiment. This was thought to be caused by the influence of the edge of the lens, which has a finite size. The dependence of convergent characteristics for oblique incidence was also compared with the results by the hybrid method.","PeriodicalId":120840,"journal":{"name":"Europe Oceans 2005","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117183611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A study on the use of SAR polarimetric data to observe oil spills","authors":"M. Migliaccio, M. Tranfaglia","doi":"10.1109/OCEANSE.2005.1511709","DOIUrl":"https://doi.org/10.1109/OCEANSE.2005.1511709","url":null,"abstract":"In this paper a new procedure to discriminate different surface films by means of SAR polarimetric data is proposed. SAR data were acquired on October 11, 1994 during SIR-C/X-SAR mission, named SRL-2. The dark features characterizing different surface films are analysed using eigenvalues and eigenvectors of the coherence matrix. Results of this study give rise to the conclusions that SAR polarimetric data are a key tool to discriminate oil spills from biogenic/anthropogenic surface films to reduce the number of false alarms.","PeriodicalId":120840,"journal":{"name":"Europe Oceans 2005","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121809055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ESONET: toward an European network of excellence on subsea observatories","authors":"R. Person, J. Marvaldi, I. Priede, J. Mienert, T. V. van Weering, O. Pfannkuche, N. O'neill, A. Tselepides, L. Thomsen, P. Favali, F. Gasparoni, N. Zitellini, C. Millot, H. Gerber, Jorge Miguel Alberto de Miranda","doi":"10.1109/OCEANSE.2005.1513269","DOIUrl":"https://doi.org/10.1109/OCEANSE.2005.1513269","url":null,"abstract":"ESONET proposes a network of sea floor observatories around the European Ocean Margin from the Arctic Ocean to the Black Sea for strategic long term monitoring as part of a GMES with capability in geophysics, geotechnics, chemistry, biochemistry, oceanography, biology and fisheries. Long-term data collection and alarm capability in the event of hazards (e.g. earthquakes) will be considered. ESONET will be developed from networks in key areas where there is industrial sea floor infrastructure, scientific/conservation significance (e.g. coral mounds) or sites suitable for technology trials (e.g. deep water close to land).","PeriodicalId":120840,"journal":{"name":"Europe Oceans 2005","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121100673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-frequency DPSK modulation for long-range underwater acoustic communication","authors":"Jianguo Huang, Yong-En Chen, Qunfei Zhang, Xiaohong Shen, F. Wang","doi":"10.1109/OCEANSE.2005.1513207","DOIUrl":"https://doi.org/10.1109/OCEANSE.2005.1513207","url":null,"abstract":"Long-range shallow water channels are characterized by severe channel fading and low available signal to noise ratio (SNR). In classical underwater acoustic communication systems for above channels, incoherent MFSK modulation, or coherent modulation based on spatial diversity and adaptive equalizations are employed. Although being robustness to fading channels, the incoherent modulation cannot solve efficiently the conflict demands between the high signaling rate and reliability. Large receiver arrays may be restricted to be used for some size limited receiver platforms. A novel multi-frequency NDPSK (MFSK-NDPSK) modulation approach for long-range underwater acoustic communications is presented in this paper which is well suited in shallow water channels. The proposed approach is an efficient combination of MFSK and NDPSK modulation. Signals are NDPSK modulated with multi-carrier frequencies, and the carrier frequencies of adjacent symbols are located in different subbands. Information is transmitted by both frequencies and phases of signals. The theoretical analysis and simulation results are given, and also the experiments in lake were conducted. The results demonstrate that compared with single-carrier modulation, the MFSK-NDPSK modulation can increase data rate in same communication range, or increase the communication range while keeping the same data rate due to input SNR can be increased to improve the performance of decreasing inter-symbol interference and increasing reliability of communication systems.","PeriodicalId":120840,"journal":{"name":"Europe Oceans 2005","volume":"139 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116221993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Real-time sonar system using acoustic lens and numerical analysis based on 2D/3D parabolic equation method","authors":"Y. Takase, T. Anada, T. Tsuchiya, N. Endoh, N. Nakamura, T. Tukioka","doi":"10.1109/OCEANSE.2005.1511678","DOIUrl":"https://doi.org/10.1109/OCEANSE.2005.1511678","url":null,"abstract":"The autonomous underwater vehicle mounted on the forward obstacle avoidance sonar is developed to investigate ocean environments. In order to obtain real time, high efficiency and clear acoustic images, the real-time sonar system using an acoustic lens has been studied. The propagation of sound through acoustic lenses can be modeled using either the ray-tracing, wave acoustics or a combination of both. In this paper, the sound pressure near the focal area of the acoustic lenses is studied by using the parabolic equation methods. In conclusions, the acoustic lens simulation based on wave acoustics offers a valid means for predictions in the performance of acoustic lenses before fabrication.","PeriodicalId":120840,"journal":{"name":"Europe Oceans 2005","volume":"149 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116391217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Circular synthetic aperture sonar design","authors":"A. D. Friedman, S. K. Mitchell, T. Kooij, K. Scarbrough","doi":"10.1109/OCEANSE.2005.1513201","DOIUrl":"https://doi.org/10.1109/OCEANSE.2005.1513201","url":null,"abstract":"Medical imaging enjoys a reputation of applying multi-aspect sensing to construct internal maps of patients. The CAT scan evokes a concept of an X-ray probe moving around the patient; the multi-aspect data is processed to construct images of the areas of interest. In contrast, advanced acoustic imaging of objects on the ocean floor has to date relied only on high resolution sensing from limited aspect angles using data gathered on straight-line trajectories. With the increased application of UUVs, it is fitting to consider the factors that govern the design of sonar that can reconstruct images taking advantage of data with aspect diversity. One future paradigm will be circular synthetic aperture sonar (CSAS) using tomographic methods to reconstruct scenes of interest from data obtained over a full circular aperture. This presentation will address the parameters and procedures that play a role in CSAS and the relations between them that govern the performance of such a system. The design of a CSAS for high resolution surveillance of objects on the ocean bottom depends on parameters such as the diameter of the circular trajectory, the speed of the platform, the size of the imaged circle, and the ping repetition rate. The spatial and range resolutions are functions of the sonar signal wavelength and its bandwidth. These parameters define in turn the maximum allowable uncorrectable platform position errors, which lead to defining the requirements of the hypernavigation system that is needed to correct for the errors between the actual ping and receiver positions and the ideal sonar trajectory used in the main imaging computation. A possible realization of such a navigation system is described in the presentation. The ping repetition rate requirements are determined by the largest dimension and shape of the reflecting areas to be imaged. Analytical expressions relating all of the above mentioned design parameters are derived. These relationships define various performance metrics as functions of the deployment parameters, allowing optimization of search strategies to maximize area coverage rate for a choice of multiple circle patterns. Images of several objects using data from a turntable testbed at Lake Travis Test Station of the Applied Research Laboratories of the University of Texas at Austin will be shown and discussed in relation to the design and test parameters.","PeriodicalId":120840,"journal":{"name":"Europe Oceans 2005","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115098709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of space-time block code and layered space-time MIMO systems for an underwater acoustic channel","authors":"R. Ormondroyd, J. S. Dhanoa","doi":"10.1109/OCEANSE.2005.1511721","DOIUrl":"https://doi.org/10.1109/OCEANSE.2005.1511721","url":null,"abstract":"The paper considers the viability of exploiting the spatial diversity that exists in shallow water, doubly-spread, underwater acoustic communications channels to use space-time methods. Using a simple 2D geometric ray model of an underwater acoustic channel, it is shown that sufficient spatial diversity exists for the underwater channel to be treated as a MIMO channel supporting space-time processing. Two different types of space-time communications system are examined: a space-time block code and a layered space-time system. Depending on the separation of the transducers, it is shown that the bit error probability performance of the two systems for the simple 2D acoustic channel can be close to that provided by an ideal Rayleigh channel in which each path suffers independent and uncorrelated fading.","PeriodicalId":120840,"journal":{"name":"Europe Oceans 2005","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116290646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The automatic fusion of classified sidescan sonar mosaics using CML-RTS and Markov random fields","authors":"S. Reed, I. Tena Ruiz, C. Capus, Y. Pétillot","doi":"10.1109/OCEANSE.2005.1513173","DOIUrl":"https://doi.org/10.1109/OCEANSE.2005.1513173","url":null,"abstract":"This paper presents a framework for registering and fusing classified sidescan sonar data. It builds on recent advances in navigation and registration for improved mosaicing, applying novel fusion algorithms to integrate data from overlapping sidescan survey lines to produce large scale classified mosaics. While typical mine-counter-measures (MCM) and rapid environmental assessment (REA) missions provide various over-lapping views of the same region of seafloor, research on sidescan image analysis has traditionally concentrated on the analysis of individual images. The available information from the other images, relating to the same region of seafloor, is generally not considered. The image registration and mosaicing process allows this complementary data to be fused, producing an improved final classification result. The sidescan imagery is first pre-processed through the application of advanced radiosity correction algorithms. Following radiosity correction, texture segmentation for the data presented in this paper is achieved using features derived from the averaged normalised power spectral density. The individual classification maps are georeferenced and coregistered using a Concurrent Mapping and Localisation Rauch-Tung-Striebel (CML-RTS) procedure. This uses local landmarks within the individual images and the AUVs navigation data to generate a more accurate and smooth navigation trajectory. This trajectory is used to produce the registered classification mosaics. The coregistered classification results are then fused to produce an improved class mosaic for the entire survey region. The fusion model uses a voting scheme to initialize the seafloor map after which a Markov random field (MRF) model is used to produce the final fused classification mosaic. The entire process (classification, registration and fusion) is demonstrated on real sidescan data taken at the Saclant Centre, La Spezia, Italy.","PeriodicalId":120840,"journal":{"name":"Europe Oceans 2005","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114882128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PHD filter multi-target tracking in 3D sonar","authors":"Daniel E. Clark, J. Bell, Y. D. Saint-Pern, Y. Pétillot","doi":"10.1109/OCEANSE.2005.1511723","DOIUrl":"https://doi.org/10.1109/OCEANSE.2005.1511723","url":null,"abstract":"The Probability Hypothesis Density (PHD) Filter was developed as a method for tracking a time varying number of targets without data association. The first order statistical moment of the multiple target posterior distribution called the Probability Hypothesis Density which is represented by discrete samples or particles gives the expected locations of the targets. This property is used instead of the full multi-target posterior distribution as it is rcquires significantly less computation and particle tilter implementations have demonstrated lhe potential of the algorithm to be used for real-time tracking applications. In this article, an application of the Particle PHD Filler is demonstrated to track a variable number of objects in threedimensiond sonar images estimating both the number of targets and their locations. The number of targets is estimated at each iteration by computing the mass of lhe particle weights. The locations of the targets are determined by extracting peaks of the PHD which is a distinct task from the computation of the particles. Previous approaches have used the Expectation Maximisation (EM) algorithm to fit a Gaussian mixture model whose time complexity is quadratic in the number of targets which is not ideal for a real-time tracking appiication and so alternative clustering techniques are considered here. A comparison is made between the methods for the accuracy of estimation, robustness and the time taken.","PeriodicalId":120840,"journal":{"name":"Europe Oceans 2005","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121732861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bathymetric sidescan sonar : a system dedicated to rapid environment assessment","authors":"B. Zerr, S.L. Goanvic, B. L. Breton, C. Genty","doi":"10.1109/OCEANSE.2005.1511695","DOIUrl":"https://doi.org/10.1109/OCEANSE.2005.1511695","url":null,"abstract":"The simultaneous acquisition of seabed backscattering and bathy-morphology can be achieved either by multibeam echo sounder or by bathymetric sidescan sonar. For rapid environment assessment (REA) prior to conduct mine counter measure operations, the sonar image, representing the seabed backscattering, is the primary source of information and the bathy-morphology the secondary one. Giving preference to the acquisition of the sonar image leads to operate at shallow grazing angle with high resolution imaging systems. Hence, the bathymetric sidescan sonar is well suited to complete the primary task of high resolution seabed imaging and the secondary task of acquiring simultaneously the bathy-morphology. Based on a commercial system, GESMA has developed a high resolution bathymetric sidescan sonar. After a description of the system and the array processing techniques which provides simultaneously the high resolution image and the bathy-morphology, the paper presents the experimental results from several sea trials conducted in various environments (Iroise sea-FR, Lyon gulf-FR, La Corona-SP, Ligurian Sea-IT, Victoria Harbor-CA). The analysis of these results demonstrates the potential and the limitations of the bathymetric sidescan sonar.","PeriodicalId":120840,"journal":{"name":"Europe Oceans 2005","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124023606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}