中国会展最新文献

{"title":"Shallow water stationkeeping of an autonomous underwater vehicle: the experimental results of a disturbance compensation controller","authors":"J. Riedel","doi":"10.1109/OCEANS.2000.881733","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881733","url":null,"abstract":"The continual development of computer technology has enabled the expansion of intelligent control into the field of underwater robots, where potential uses include oceanographic research, environmental monitoring and military mine countermeasures. With the naval focus shifting to operations in the littorals, and the need to lower cost of operations, tetherless autonomous vehicles are now being proposed for use in very shallow water minefield reconnaissance. These areas are dominated by a highly energetic environment arising from waves and currents. Motion control in such an environment becomes a difficult task and is the subject of this work. The main objective of the paper is to show that intervention tasks performed by intelligent underwater robots are improved by their ability to gather, learn and use information about their working environment. Using a new generalized approach to the modeling of underwater vehicles, which directly includes disturbance effects, a new disturbance compensation controller (DCC) is proposed. The DCC, employing onboard vehicle sensors, allows the robot to learn and estimate the seaway dynamics. This self-derived knowledge is embedded in a non-linear sliding mode control law which allows significantly improved motion stabilization. The performance of the DCC has been experimentally verified in Monterey Harbor using the NPS Phoenix AUV.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"43 1","pages":"1017-1028 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80915300","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":"Automated matched-field tracking in shallow water 2000 IEEE international symposium","authors":"P. Baxley, R. Brannan","doi":"10.1109/OCEANS.2000.881369","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881369","url":null,"abstract":"Matched-field tracking (MFT) is the application of matched-field processing (MFP) to a moving source. This involves either post-processing MFP outputs to detect tracks of target peaks, or generalizing the search space of the processor to include candidate source tracks. The latter approach, referred to as automated MFT, is examined in this paper. By integrating matched-field correlations over candidate source tracks, the true track can be detected (as determined by the highest integrated correlation) and the target track parameters estimated. In addition, the integration process results in a gain in detectibility for the true source track. For the general case of a source moving in three-dimensions through an environment which varies in three dimensions, the technique is computationally restrictive, because of the large number search parameters. However, for a vertical line array (VLA) in a range-independent environment, and an assumption of constant-depth, constant range-rate tracks, the search space is reduced to the range and depth at the beginning (or end) of the track, and the range-rate. The integration process can then be performed by a simple shift-then-average scheme applied to range-depth ambiguity-surface time samples. For a constant-velocity source, the range-rate can generally be assumed to be constant, except for a period in which it passes through the closest-point-of-approach (CPA). For that case, a CPA estimator, which attempts to match data from a moving source with that expected for candidate CPA tracks, is implemented. For horizontal line arrays (HLAs), a hybrid planewave beamforming/matched-field processing, track-before-detect (TBD) technique, which takes advantage of the azimuthal-filtering capability of HLAs to limit the bearing search, may be used. This approach provides estimates of the full track parameters (range, depth, course, and speed) with a processing load substantially lower than that required for a fully three-dimensional MFP search. These techniques are applied to experimental tonal data collected on a VLA and HLA during the 1996 Shallow Water Evaluation Cell Experiment (SWellEX-96), which occurred in 200-m water, 6 km southwest of San Diego.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"75 1","pages":"869-875 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80935844","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":"Quadratic phase coupling analysis of passive sonar data using biphase techniques","authors":"L. Persson, R. Lennartsson, J.W.C. Robinson, S. McLaughlin","doi":"10.1109/OCEANS.2000.881740","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881740","url":null,"abstract":"In this work we report on the application of a higher order statistics based method that can be used to improve passive signature estimation over the conventional bispectrum methods. The method employs the biphase for extraction of frequency triplets with possible quadratic phase coupling. We demonstrate the method using data recorded by bottom mounted hydrophones during a sea trial in the Baltic Sea with a small fiberglass motor boat as a target. Several frequency pairs are shown to exist for which, according to the biphase test, there is significant quadratic phase coupling. This information can be useful to form complementary features for passive signature classification.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"1 1","pages":"1053-1057 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78732782","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":"Intelligent autonomy for the Manta Test Vehicle","authors":"M. Ricard, M. Keegan","doi":"10.1109/OCEANS.2000.881776","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881776","url":null,"abstract":"The Navy's next generation unmanned undersea vehicle (UUV) missions include (1) long-range intelligence, surveillance and reconnaissance (2) tactical oceanography and (3) antisubmarine warfare. To support the vision to perform these missions with unmanned platforms, significant increases in the levels of system autonomy and on-board autonomous processing are required. The Naval Undersea Warfare Center (NUWC), Division Newport and the Charles Stark Draper Laboratory have teamed to perform research and development in the area of autonomy and autonomous processing necessary to support next-generation UUV missions. The paper outlines the autonomy requirements of these missions with respect to the capabilities of UUVs that are fielded or currently under development. The approach taken to develop the autonomous processing capabilities required of these missions is outlined. The paper also discusses the progress that has been made in the development of the Navy's next generation autonomous, unmanned undersea vehicle testbed, the Manta Test Vehicle (MTV), The MTV is a non-traditionally shaped UUW that is being designed and fabricated by NUWC. The vehicle has the dimensions of 34 ft/spl times/16 ft/spl times/8 ft which allows significant payload capability for sensing elements and related processing equipment. MTV was conceived to help push the envelope on what could be achieved in an unmanned system and will serve as the testbed for Intelligent Autonomy R&D.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"23 1","pages":"1265-1271 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78823744","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":"TracEd: a remote acoustic seafloor characterization system for use with vertical incidence echosounders","authors":"S. Dijkstra, L. Mayer","doi":"10.1109/OCEANS.2000.881765","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881765","url":null,"abstract":"TracEd is a tool developed for the assessment of the performance of several seafloor characterization methods. It is attempted to give the user a full understanding of the various aspects of collected data through simultaneous visualization in various data spaces.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"52 1","pages":"1211-1217 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76062135","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":"Dispersive surface classification: local analysis of optical image sequences of the water surface to determine hydrographic parameter maps","authors":"C.M. Senet, J. Seemann, F. Ziemer","doi":"10.1109/OCEANS.2000.882196","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.882196","url":null,"abstract":"The appearance of the sea surface is a spatio-temporal phenomenon. Features observed on the water surface are, e.g. wave fields or wind streaks. The acquisition and analysis of image sequences therefore allows a complete (spatio-temporal) representation of the sea state. Ship- or land-based nautical radars are used in the field and optical sensors are used in hydraulic wave tanks to acquire image sequences. A technique using a combination of image sequences acquired from CCD cameras and in situ data sets is used to observe and analyze the spatio-temporal sea surface wave field in a hydraulic wave tank. A new image sequence processing method, called DiSC (Dispersive Surface Classificator), was developed to create maps of physical parameters for inhomogeneous, dispersive surfaces. The analysis technique allows the determination and representation of hydrographic parameters such as the near-surface current-velocity vector, the water depth, and the full-directional wave spectra. DiSC, applied to image sequences of the sea surface, is useful for impact studies on maritime structures, beach studies, and other studies in wave facilities. The analysis method also has been tested for nautical X-band radar image sequences. The presented method enables oceanographers and offshore and coastal engineers to study the spatio-temporal behaviour of wave fields in nature and in hydraulic wave tanks for monitoring and planning purposes.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"127 1","pages":"1769-1774 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79545182","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-aspect synthetic aperture sonar","authors":"Jose E. Fernandez, J. Christoff","doi":"10.1109/OCEANS.2000.881256","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881256","url":null,"abstract":"Multi-aspect or multi-look processing is known to improve the image quality and target detection capability of high resolution synthetic aperture sonar (SAS) imaging systems. We present in this paper a brief description on the topic and typical results obtained from sea data collected while fielding the High Frequency/Low Frequency Synthetic Aperture Sonar (HF/LFSAS).","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"71 1","pages":"177-180 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79326480","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":"Hypothesis-feedback equalization for direct-sequence spread-spectrum underwater communications","authors":"M. Stojanovic, L. Freitag","doi":"10.1109/OCEANS.2000.881246","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881246","url":null,"abstract":"Direct-sequence code-division multiple-access is considered for underwater acoustic communication networks. Unlike in the majority of spread-spectrum radio systems, intersymbol interference cannot be neglected, and time variability of the channel requires that receiver adaptation be performed at the chip, rather than the bit rate. Adaptive decision-feedback equalization, which has successfully been used for single-user underwater communications, is not directly applicable to spread-spectrum signals because of the delay in the despreading process and the lack of reliable chip decisions. To overcome this problem, a receiver is proposed which feeds back hypothesized, rather than the actual decisions. Numerical examples demonstrate the receiver's ability to cope with time varying channel distortions and preserve the processing gain when conventional, symbol-rate adaptive methods fail.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"45 1","pages":"123-129 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74352248","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":"Three-dimensional reconstruction of the oscillatory free-surfaces of a flow over antidunes: stereoscopic and velocimetric techniques","authors":"D. Douxchamps, D. Devriendt, H. Capart, Christophe Craeye, B. Macq, Y. Zech","doi":"10.1109/OCEANS.2000.881822","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881822","url":null,"abstract":"The authors present imaging methods developed to characterize the oscillatory free-surface of rapid flows and apply them to torrential currents propagating over sediment antidunes. The aim is to obtain high-resolution relief maps of the free-surface topography, in order to highlight the regular spatial patterns associated with the bedforms. Two measurement principles are outlined and tested, both based on the imaging of floating tracers dispersed on the rapidly flowing surface. The first relies on direct stereoscopic measurements obtained using two cameras, while the second exploits an original velocimetric principle allowing to derive elevation from the velocity field acquired using a single camera. The measurement procedures and image analysis algorithms are introduced for the two methods, along with the physical assumptions underlying the velocimetric principle. The results of the two techniques are compared for different free-surface patterns and good correspondence is obtained. The obtained relief maps vividly depict the variety of motifs that can evolve as a result of interaction between shallow flows and loose sediment beds.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"26 1","pages":"1535-1542 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75720544","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":"New capabilities of the REMUS autonomous underwater vehicle","authors":"M. Purcell, C. von Alt, B. Allen, T. Austin, N. Forrester, R. Goldsborough, R. Stokey","doi":"10.1109/OCEANS.2000.881250","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881250","url":null,"abstract":"Autonomous underwater vehicle technology continues to advance at a rapid pace. REMUS (Remote Environmental Monitoring UnitS), developed by the Oceanographic Systems Laboratory at the Woods Hole Oceanographic Institution, is one of the most widely used autonomous underwater vehicles in the world. Each year REMUS vehicles participate in numerous field exercises in support of scientific and navy research objectives. Designed for coastal operations, REMUS is normally deployed with a CTD, light scattering sensor, side scan sonar and an up-and-down looking acoustic doppler current profiler (ADCP). Additional sensors are easily integrated in the vehicle and a bioluminescence instrument and a turbulence sensor package. Recent development efforts have improved the REMUS vehicle overall design and performance, and include integration of two new sensors. Vehicle improvements include lower drag, a new propulsion, new lithium-ion batteries and a new external interface. Maximum speed has been increased from 1.75 m/s to almost 3 m/s (6 knots) and mission length has increased to 22 hours at the 1.5 m/s (3 knots) cruising speed. REMUS has been used to demonstrate a new autonomous underwater vehicle application: plume mapping. A rhodamine fluorometer was installed to map a plume on a steep sloping sea floor. Results from the field test demonstrate the effectiveness of an AUV as a tool in this task. A second REMUS vehicle has been deployed with an optical sensor package. The instruments in the package include a chlorophyll fluorometer and up-and-down looking, seven channel radiometers. This package combined with the standard CTD and ADCP generates a significant scientific data set, which supports both physical and biological oceanographic research.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"487 1","pages":"147-151 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73125478","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}