中国会展最新文献

{"title":"Engineering the world's largest DGPS Network","authors":"D. Wolfe, C. Judy, E.J. Haukkala, D. J. Godfrey","doi":"10.1109/OCEANS.2000.881237","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881237","url":null,"abstract":"The U.S. Coast Guard's is part of a team that is implementing the world's largest ground-based GPS augmentation service, Nationwide DGPS (NDGPS). The U.S. Coast Guard's original responsibility was to provide DGPS coverage to all harbors and harbor approaches of the United States. The Maritime DGPS broadcast site network built to meet this requirement provided differential corrections along the Atlantic, Pacific and Gulf coasts, the Great Lakes, Hawaii, Puerto Rico and the southern coast of Alaska. Two control sites were also built to monitor the performance and integrity of the individual DGPS broadcasts. As the number of users and uses of DGPS increased, the need to expand the DGPS coverage area has also increased. An agreement with the U.S. Army Corps of Engineers expanded the U.S. Coast Guard's DGPS coverage to the inland rivers of the U.S.. The NDGPS expansion effort, scheduled to have over 126 broadcast sites, is designed to provide double terrestrial DGPS coverage across the entire continental United States and Alaska and meet all surface transportation navigation requirements. Once the requirement of a NDGPS network was identified, the Department of Transportation (DOT) assembled a team from several DOT agencies to determine the best way to meet this need. This team decided the most cost effective and efficient way to create a nationwide system was to expand the U.S. Coast Guard's Maritime DGPS network. Based upon their experience with providing DGPS coverage, the U.S. Coast Guard was designated the lead agency responsible for the design, construction and implementation of the broadcast and control sites in the NDGPS expansion. This paper explains the basic operating concepts of the U.S. Coast Guard's DGPS Network: the equipment and functions of the broadcast site, control site and communication's network, and how the U.S. Coast Guard ensures the integrity of the system and differential corrections on a continuous basis. It then describes the challenges the U.S. Coast Guard is facing trying to provide a nationwide network and reviews the advantages and effort involved in converting obsolete U.S. Air Force Ground Wave Emergency Network sites into DGPS broadcast sites. Finally it reviews the U.S. Coast Guard's efforts to improve the accuracy, reliability and performance of the entire DGPS Network.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"37 1","pages":"79-87 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87374542","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 model based system for simultaneously estimating bathymetry and sound speed characteristics-simulation results","authors":"D. B. Cousins, J.H. Miller","doi":"10.1109/OCEANS.2000.881263","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881263","url":null,"abstract":"This paper presents an adaptive bathymetric estimation algorithm (ABE) for use with forward-looking hull mounted sonar in shallow water environments. In addition to providing improved positional estimates of ocean bottom contacts in front of the host vehicle, it will automatically estimate and adapt to changes in the local sound speed. Preliminary simulation results are given for a simple two-dimensional encounter of a single bottom contact using an isovelocity, straight line ray model.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"4 1","pages":"213-219 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89202905","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":"Marine seafloor sediment profiling and classification in the Arctic Ocean","authors":"T. Opishinski, D. Caulfield","doi":"10.1109/OCEANS.2000.882215","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.882215","url":null,"abstract":"Ocean Data Equipment Corporation redesigned their FM Chirp sub-bottom profiler, the Bathy 2000P, for operation aboard a US Navy Sturgeon-class nuclear powered submarine. Normally operated from a surface vessel, the Bathy 2000P was customized to meet specifications provided by scientists from Lamont-Doherty Earth Observatory of Columbia University for use as an Arctic research tool. An overview of the system design criteria is given that details the difficulties posed by operation aboard a submarine surveying in the Arctic and how the system was tailored to meet the scientific objectives for operation in a complex environment. Successful operation of the Bathy 2000P during two annual Submarine Science Ice Expeditions (SCICEX) has provided seafloor and sediment sonar data previously unavailable to the scientific community. High-resolution acoustic images of the Arctic marine sub-bottom and topographic contours are presented and corroborate the use of a submarine as a platform for acoustic acquisition of geophysical data. Additional processed data, generated using a unique suite of algorithms to derive spectral and absorption loss characteristics are presented. These techniques illustrate the possibility of extending our geophysical knowledge through sediment characterization of the Arctic basin without the need for extended physical sampling.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"35 1","pages":"1901-1906 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91237777","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":"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":"Marine cathodic protection-historical trends and recent accomplishments","authors":"W. Hartt","doi":"10.1109/OCEANS.2000.882199","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.882199","url":null,"abstract":"Historical hallmark accomplishments pertaining to design and function of cathodic protection (cp) systems for marine structures are listed and briefly discussed. The newly developed first-principles based slope parameter method and a unified design equation developed therefrom are described and compared to present standard design practice. Application, including advantages and limitations, of this approach to both galvanic and impressed current cp systems upon space frame (oil production platforms, for example), two dimensional (ship hulls), and one dimensional (pipelines and cables) structures is described. It is demonstrated that this method is advantageous compared to that of existing standard recommended practices.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"164 1","pages":"1787-1793 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77918469","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":"Modal mapping in shallow water using synthetic aperture horizontal arrays","authors":"G. Frisk, K. M. Becker, J. Doutt","doi":"10.1109/OCEANS.2000.881258","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881258","url":null,"abstract":"An experimental technique is described for mapping the wavenumber spectrum of the normal mode field as a function of position in a shallow water waveguide with three-dimensional variation in its acoustic properties. These modal maps provide a characterization of the modal properties of the waveguide, can be used as input data to inversion techniques for inferring the 3D geoacoustic properties of the bottom, and improve our ability to localize and track source. The experimental configuration consists of a source radiating one or more pure tones to a field of freely drifting buoys, each containing a hydrophone, GPS navigation, and radio telemetry. A key component of the method is the establishment of a local differential GPS system between the source ship and each buoy, thereby enabling the determination of the positions of the buoys relative to the ship with submeter accuracy. In this manner, the drifting buoys create 2D synthetic aperture horizontal arrays along which the modal evolution of the waveguide can be observed in the spatial domain, or after beam forming, in the horizontal wavenumber domain. Typical results from two modal mapping experiments (MOMAX) are presented in which fixed and moving source configurations were used to transmit pure tones in the band 50-300 Hz to several buoys at ranges up to 10 km. MOMAX I was conducted in about 70 m of water off the New Jersey coast in March, 1997, while MOMAX II was carried out in 50-150 m water depths in the Gulf of Mexico in February, 1999. A striking feature of these data is the remarkable stability and regularity of the phase, although the magnitude displays a complex multimodal interference pattern.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"79 1","pages":"185-188 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88179288","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":"Matched image processing for undersampled synthetic aperture sonar","authors":"Geoffrey S. Edelson, C. Gedney, K. Rolt, Philip Abbot, Ira Dyer","doi":"10.1109/OCEANS.2000.881259","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881259","url":null,"abstract":"An approach conceptually similar to matched field processing that mitigates the effects of aliasing in undersampled synthetic aperture sonar images is presented. This pattern matching technique is performed in the complex image domain and reduces the strength of the aliases by cross-correlating replica sub-images with an aliased undersampled synthetic aperture sonar image. The issue of mitigating multipath effects is not addressed but matched image processing could be combined with a more conventional range/depth matched field processing algorithm to achieve even greater image improvements in multipath environments.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"20 1","pages":"189-194 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88219528","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":"Spread-spectrum based adaptive array receiver algorithms for the shallow-water acoustic channel","authors":"C. Tsimenidis, O. Hinton, B. Sharif, A. Adams","doi":"10.1109/OCEANS.2000.881768","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881768","url":null,"abstract":"In this paper we propose spread spectrum-based adaptive array receiver structures for reliable low data-rate multi-access communication in the shallow-water acoustic channel. The performance of the proposed receiver algorithms is evaluated by employing both offline processing and simulation. Results indicate that multi-access error-free reception is attainable in network scenarios where transmission is multipath impaired.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"16 1","pages":"1233-1237 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87920152","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":"NeMONet: a near real-time deep ocean observatory","authors":"S. Stalin, H. Milburn, C. Meinig","doi":"10.1109/OCEANS.2000.881317","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881317","url":null,"abstract":"The New Millennium Observatory Network (NeMONet) system was deployed, by NOAA/PMEL, in the NE Pacific along the Juan de Fuca Ridge in September 1999. This system is one of the first remote underwater, near real-time observatories implemented with the capability of bringing scientific data directly from ocean depths to the desktop. Located approximately 300 miles offshore and 1500 meters underwater, the assemblage was positioned adjacent to a hydrothermal vent near an underwater volcano with the ability to collect and transmit near real-time images of vent activity and temperature measurements at specific intervals for approximately one year. The basic design goal was proof of concept and to accommodate a broad spectrum of scientific applications ranging from chemical to biological to geographical data collection in future deployments. The NeMONet consists of a sub-sea unit that was strategically positioned on the seafloor with a Remotely Operated Vehicle (ROV) and a taut-line surface mooring that was deployed nearby. Communication from the seafloor to the surface is made possible by using commercial acoustic modems and from the buoy to shore via a geostationary satellite. All buoy and sub-sea communications are handled by carefully programmed controllers with hardware designed for low power and data compression to fit the narrow bandwidth of the transmission paths. The images and data are placed on the Web shortly after being received ashore. The successful operation of the NeMONet system with the first deployment has given encouragement to develop a follow-on system and make plans for future enhancements to the observatory.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"134 1","pages":"583-587 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90883980","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}