Oceans '97. MTS/IEEE Conference Proceedings最新文献

{"title":"Measurement of ultraviolet radiation distribution on coastal area","authors":"Y. Ohga, T. Kawanishi, S. Furuuchi, K. Takahashi","doi":"10.1109/OCEANS.1997.634449","DOIUrl":"https://doi.org/10.1109/OCEANS.1997.634449","url":null,"abstract":"The aim of this study is to clarify the distribution of ultraviolet radiation in coastal and inland areas. An adhesive-backed ultraviolet indicator, which is able to easily measure the amount of integral ultraviolet radiation by color change, was utilized. The results show the characteristics of the indicator and the distribution of ultraviolet radiation in coastal and inland areas.","PeriodicalId":259593,"journal":{"name":"Oceans '97. MTS/IEEE Conference Proceedings","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134090903","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 manned submersible as an effective sampling and imaging platform","authors":"D. Liberatore, T. Askew, R. Tusting, S. Olson","doi":"10.1109/OCEANS.1997.634335","DOIUrl":"https://doi.org/10.1109/OCEANS.1997.634335","url":null,"abstract":"Remotely operated vehicles (ROVs), tow bodies and autonomous undersea vehicles (AUVs) are increasingly being used as platforms for underwater measuring, collecting and imaging. However, there are tasks for which a free-swimming, manned vehicle is a cost-effective platform. The effectiveness of an in-situ operator, rather than one remotely located from the sampling or measurement platform, is primarily due to two factors: intelligent vision and adaptive decision making. In spite of the advances made in stereo-vision systems and telepresence, the on-site human eye often outperforms other vision systems. The presence of an operator on board the vehicle also allows decisions to be made rapidly, or an experiment to be modified when conditions are not as anticipated. This paper describes several successful, ongoing projects utilizing Harbor Branch Oceanographic Institution's (HBOI) manned submersibles. One project involved imaging natural and man-made objects near the ocean floor using a laser-line-scanning (LLS) system equipped with multiple receivers. This system was interfaced to the Research Submersible CLELIA and was employed on five missions during 1996. Spectacular high-resolution black and white, fluorescence and color images were obtained. Inter-disciplinary research cruises to cold-seep regions of the Gulf of Mexico with the JOHNSON-SEA-LINK (J-S-L) submersibles allow multi-parameter probing of brine pools and specialized collection of biological, geological and geochemical samples. For example, methane ice samples are removed from deposits on the ocean floor at a depth of 2000 ft. and transported under pressure to a laboratory on board the support vessel for analysis.","PeriodicalId":259593,"journal":{"name":"Oceans '97. MTS/IEEE Conference Proceedings","volume":"257 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133898721","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":"Bottom detection for multibeam sonars with active contours","authors":"L. Yang, T. Taxt, F. Albregtsen","doi":"10.1109/OCEANS.1997.624118","DOIUrl":"https://doi.org/10.1109/OCEANS.1997.624118","url":null,"abstract":"In multibeam sonar bathymetry, a receiving array is used to form a fan-shaped beam sector. Bottom echoes of near-normal incident angles are usually detected based on the amplitude of the received signal. To detect bottom echoes of oblique incident angles, it is common to use the phase information obtained by subarray interferometry. The type of the bottom echo is not known a priori. Hence, which of the two bottom detection methods to use for a particular beam is determined by ad hoc criteria. Localization errors of the bottom are often the consequence of choosing the wrong bottom detection method. In this paper, the authors propose to use a bottom image transform and an active contour model to integrate the amplitude and phase information, so the bottom echoes from all directions can be detected by a single algorithm. Promising results were obtained in the authors' evaluation using Simrad EM3000 sonar data recorded from shallow water.","PeriodicalId":259593,"journal":{"name":"Oceans '97. MTS/IEEE Conference Proceedings","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124433055","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":"Conceptual re-design techniques utilised for optimisation of a mine countermeasure towed acoustic generator control system","authors":"J. S. Baker, D. Cowling","doi":"10.1109/OCEANS.1997.624177","DOIUrl":"https://doi.org/10.1109/OCEANS.1997.624177","url":null,"abstract":"Acoustic replication of a surface vessel is achieved by use of an electrohydraulic towed generator emitting a range of low and audio frequency signal spectra patterns within a specified bandwidth. System performance and endurance inadequacies inherent within the design for over a decade necessitated a complex modelling and simulation exercise for key parameter identification of problematic subsystem failures. Previous system updates were based purely on experimental testing and subsequently proved ineffective when implemented. The system comprises three key areas, each with its own complex transient behaviour. These are the input transmission drive, the hydraulic actuation system and the electronic feedback control system. The complex interaction between these three subsystem could only be assessed using modern computer simulation techniques to assist experimental development. This paper describes the development and application of simulation techniques to overcome the reliability and endurance failures. The paper identifies the process involved in failure categorisation, subsystem optimisation, hardware development and results achieved. In essence, the units problems manifested itself as a destructive resonance which produced excessive pressure oscillation in the system service lines. The main system problem was initially thought to be due to the electrohydraulic actuation and feedback control system; however subsequent instrumentation to obtain torque fluctuations on the input drive to the system demonstrated that the original simulation model did not fully represent the chain of events leading to the problem. The model was improved by the addition of a complex input drive comprising four degrees of freedom with representative stiffness and backlash terms. This was shown to reproduce the observed behaviour and highlight the input drive as the prime cause of system malfunction. The simulation provided precise input drive parameter changes necessary to strengthen the drive members and thus overcome the input resonance problem.","PeriodicalId":259593,"journal":{"name":"Oceans '97. MTS/IEEE Conference Proceedings","volume":"54 32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127673261","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":"Satellite radar scatterometer (NSCAT) studies of ocean surface stress in near coastal regions","authors":"D. Weissman","doi":"10.1109/OCEANS.1997.624156","DOIUrl":"https://doi.org/10.1109/OCEANS.1997.624156","url":null,"abstract":"Summary form only given. This study addresses the consistency of the surface friction velocity derived from the scatterometer normalized radar cross section (NRCS) measurements and the directional properties of the NRCS (SIGMA-O) measurements in near coastal regions. NSCAT data (Level 1.7) colocated with numerous NDBC buoys is being analyzed to determine the variability of the directional properties of the colocated fore and aft beam measurements. These orthogonal measurements of the NRCS (25 km resolution, and converted to linear power units) by the fore and aft beams are used to calculate the Fourier series coefficients of the azimuthal model: AO and A2. The spatial variability of A2/AO, as an indication of how the azimuthal modulation varies, is being examined in the vicinity of buoys off the U.S. Atlantic coast, in the Gulf of Mexico and along the coast of California. Preliminary results show excellent agreement between the satellite derived friction velocity (u*) using the FASINEX/Weissman Ku-band model function and buoy measurements. An alternate method of estimating u* using the satellite (Level 2.0) wind speeds and a drag coefficient produce results with a wider scatter about the buoy-derived estimates of u*. Other results show some cases in which the A2/AO term is relatively constant for the 12-to-19 SIGMA-O cells that lie within the 10 square region centered about each buoy, and other situations in which the A2/AO values vary randomly and considerably even though the winds appear to be uniform. These latter situations are of strong interest, and are being studied to determine the possible causes of this variability. Under consideration are the long wave systems, atmospheric stability and surface material properties.","PeriodicalId":259593,"journal":{"name":"Oceans '97. MTS/IEEE Conference Proceedings","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128856208","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":"SuperBASS tripod for benthic turbulence measurement","authors":"A. Williams, D. Peters, A. Gordon, J. Trowbridge","doi":"10.1109/OCEANS.1997.634419","DOIUrl":"https://doi.org/10.1109/OCEANS.1997.634419","url":null,"abstract":"Seafloor flow induced processes are generally studied from rigid structures. Where undisturbed flow is important, open structures are used, tripods being the choice for omnidirectional flow. Stiffness as well as openness is important to delay excitation of vibrations that can contaminate velocity measurements, masking turbulence in the flow. SuperBASS, measuring velocity and turbulence at seven heights from 0.3 to 7 m above bottom, is 8 m tall, 4 m between footpads, weighs 530 kg, and is stable to overturning to 1 m/s flow velocity. A \"Y\" channel of rectangular cross section from the bottom of the legs supports the base of the acoustic current meter array, eliminating the need for stiffener struts on the faces of the tripod. While this design reduces turbulence at all sensor heights that would have come from the wake of upstream stiffening struts, a mean upward component of flow is observed on the lower sensors from separation of the flow over the \"Y\" channel near the seabed.","PeriodicalId":259593,"journal":{"name":"Oceans '97. MTS/IEEE Conference Proceedings","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128501940","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":"Verification and validation of underwater models","authors":"D. W. Gledhill, J. Illgen","doi":"10.1109/OCEANS.1997.634413","DOIUrl":"https://doi.org/10.1109/OCEANS.1997.634413","url":null,"abstract":"As computational power increases and the price of software and hardware decrease, the ability to simulate the effects of oceanic currents on the performance of electronic and electroacoustic systems becomes more achievable. While the modeling of underwater effects will always be orders of magnitude more complex than atmospheric modeling, the increase in technology is causing more underwater models and simulations (M&S) to appear in the literature and on the shelf. As a result, the issue of the \"credibility\" of these models is taking on new meaning. As these models gain more use, they must undergo the verification and validation (V&V) process(es) specified by DoD. This paper presents a standard methodology for V&Ving undersea models that will document their credibility and provide the data needed for accreditation. The methodology is divided into different phases: each with a prescribed input and output, and each with documented results. ISTI has developed a methodology that has been adopted and successfully implemented by a number of different V&V programs. This methodology employs a unique use of Computer Assisted Software Engineering (CASE) tools to reverse engineer source code and produce analytical outputs (flow charts and tables) that aid the engineer/analyst in the V&V process. We have found that the use of CASE tools saves time, which equates to improvements in schedule, cost, and provides the subject matter expert far superior information to evaluate the model and/or simulation. This paper will describe the ISTI-developed methodology and how CASE tools are used in its support. Case studies will be discussed.","PeriodicalId":259593,"journal":{"name":"Oceans '97. MTS/IEEE Conference Proceedings","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116918443","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":"Design of a hydrophone array for littoral waters","authors":"K. Jenne, L. Ivey","doi":"10.1109/OCEANS.1997.624165","DOIUrl":"https://doi.org/10.1109/OCEANS.1997.624165","url":null,"abstract":"Summary form only given. This presentation documents the engineering effort, fabrication, and subsequent calibration results of a line array, USRD type F81, currently used by the U.S. Navy to collect acoustic data in littoral waters. Littoral waters present a complicated acoustic environment, but measurement difficulties can be minimized by using a transducer or array configuration designed for the specific application. The hydrophone array type F81 was designed and fabricated to assist in studying the impact that ocean biological life has on submarine sonar. Relevant engineering equations used to predict performance for transducers and arrays are the main focus and discussed in some detail, but application is also discussed. The engineering discussion includes the parameters; Free Field Voltage Sensitivity (FFVS), directional response, array capacitance, effects of cable capacitance, wiring sensors in a parallel/series combination, and sensor spacing. Additionally, selection of sensor material, the acoustic window material, and unique mechanical configurations used for fabrication are examined. Issues of reliability for underwater transducer designers are implicit throughout this presentation. The F81's low weight, flexibility, and strength help facilitate easy deployment and retrieval from nearly any research vessel of opportunity. The F81 transducer has been in service for about three years and, to date, successfully employed by the Naval Research Laboratory.","PeriodicalId":259593,"journal":{"name":"Oceans '97. MTS/IEEE Conference Proceedings","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114811196","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":"Compensation for missing sensors in a real-time measurement beamformer system","authors":"T. Gee, K. Pepe, R. Collier, K. Everman, E. Freer, R. Wetherington, G. Tarasek","doi":"10.1109/OCEANS.1997.634388","DOIUrl":"https://doi.org/10.1109/OCEANS.1997.634388","url":null,"abstract":"In the system described in this paper, an array of hydrophones with a fixed geometry is used to make accurate underwater acoustic measurements over a large frequency range. The beamforming coefficients used to weight each sensor have been optimized over the full frequency range to provide the desired accuracy for a constant beam width and high noise reduction for the ocean environment. These coefficients must be developed for numerous angular beam widths and for several steering angles, requiring considerable time (several hours) to generate off-line using parallel digital signal processors. To make the number of coefficients manageable, the array symmetry has been utilized. When sensors are missing due to inevitable failures, this symmetry no longer exists, and a new method is required to handle the arbitrary array geometry. Also, failures can occur unexpectedly, making it unreasonable to redesign the coefficients for changes in array geometry. This paper describes a compensation method that has proven successful in regaining the desired amplitude level of the beam response without modifying the existing sensor coefficients.","PeriodicalId":259593,"journal":{"name":"Oceans '97. MTS/IEEE Conference Proceedings","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127538122","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":"Corrosion resistance of certain strength wires used in small fiber-optic cables exposed to seawater","authors":"C. Sandwith, R.L. Ruedisueli","doi":"10.1109/OCEANS.1997.624120","DOIUrl":"https://doi.org/10.1109/OCEANS.1997.624120","url":null,"abstract":"Theoretical analyses and the results of corrosion tests on fiber-optic cables with different strength wires and designs are used to evaluate the suitability of the cables as candidates for use on the sea bottom. The strength wires in the cables were made of certain Inconel, stainless steel, and steel alloys and had diameters ranging from 0.008 to 0.015 in. The materials, coatings, and distribution of the wires are reviewed to evaluate their effects on cable failure modes and survivability in seawater applications on the ocean bottom. The initial, final, and average corrosion rates of the candidate cable wires and losses in cable tensile breaking strength over test periods of several months are compared. Wire corrodability, seawater corrosivity, and corrosion mechanisms are discussed, along with the relative importance and contributions of dissolved oxygen, dissolved-oxygen distribution, and crevices. Corrosion of as-received cable samples, of single cable wires, and of cable samples with jackets damaged as might be expected during installation and service life are compared and discussed. Analytical predictions of the cable loss in tensile breaking strength and experimentally measured tensile breaking strengths, including range and amount of loss, are presented. Finally, a basis is discussed for recommending wires made of Inconel 625 over wires made of 316L stainless steel. Nitronic 50 stainless steel, galvanized steel, or ungalvanized steel.","PeriodicalId":259593,"journal":{"name":"Oceans '97. MTS/IEEE Conference Proceedings","volume":"140 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127569957","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}