Pub Date : 2000-09-11DOI: 10.1109/OCEANS.2000.882204
K. Kebkal, R. Bannasch
Communication over underwater acoustic channels with strong, extended multipath can be substantially improved by using a new method based on the implementation of a sweep-spread carrier (S2C). Such a carrier consists of a succession of sweeps, which cause permanent rapid fluctuation of signal frequency. Apart from some additional useful effects such as providing multi-user access and reducing influence of narrow-band noise, the sweep-spreading represents a powerful tool enabling separation of signal multipaths by converting their time delay into frequency split of individual multipath arrivals. The steeper the sweeps, the better multipath resolution can be achieved. After signal despreading, i.e. conversion into a constant intermediate frequency, the best suitable multipath arrival (or even several of them in parallel) can be separated and analyzed. In this way, all signal parameters can be recovered with high quality. The high performance and transmission stability of this approach could be confirmed in computer simulations as well as in validation experiments with horizontal transmission in natural shallow water channels carried out since summer 1999.
{"title":"Implementation of a sweep-spread function for communication over underwater acoustic channels","authors":"K. Kebkal, R. Bannasch","doi":"10.1109/OCEANS.2000.882204","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.882204","url":null,"abstract":"Communication over underwater acoustic channels with strong, extended multipath can be substantially improved by using a new method based on the implementation of a sweep-spread carrier (S2C). Such a carrier consists of a succession of sweeps, which cause permanent rapid fluctuation of signal frequency. Apart from some additional useful effects such as providing multi-user access and reducing influence of narrow-band noise, the sweep-spreading represents a powerful tool enabling separation of signal multipaths by converting their time delay into frequency split of individual multipath arrivals. The steeper the sweeps, the better multipath resolution can be achieved. After signal despreading, i.e. conversion into a constant intermediate frequency, the best suitable multipath arrival (or even several of them in parallel) can be separated and analyzed. In this way, all signal parameters can be recovered with high quality. The high performance and transmission stability of this approach could be confirmed in computer simulations as well as in validation experiments with horizontal transmission in natural shallow water channels carried out since summer 1999.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"29 1","pages":"1829-1837 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87315751","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}
Pub Date : 2000-09-11DOI: 10.1109/OCEANS.2000.881813
T. Howarth, J. Tressler
The Naval Research Laboratory (NRL) is currently developing low frequency acoustic projectors for use in shallow water environments. Its thin profile is intended for placement onto autonomous underwater vehicles (AUVs) and unmanned underwater vehicles (UUVs). The projectors are designed with a piston mode resonant frequency below 1 kHz. The transmitting output is then followed by a secondary resonance frequency in the 50 kHz range such that the overall output can be used for broadband operation from 1 kHz to 60 kHz.
{"title":"Recent advances in thin, low frequency acoustic projectors","authors":"T. Howarth, J. Tressler","doi":"10.1109/OCEANS.2000.881813","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881813","url":null,"abstract":"The Naval Research Laboratory (NRL) is currently developing low frequency acoustic projectors for use in shallow water environments. Its thin profile is intended for placement onto autonomous underwater vehicles (AUVs) and unmanned underwater vehicles (UUVs). The projectors are designed with a piston mode resonant frequency below 1 kHz. The transmitting output is then followed by a secondary resonance frequency in the 50 kHz range such that the overall output can be used for broadband operation from 1 kHz to 60 kHz.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"128 1","pages":"1477-1480 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88179730","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}
Pub Date : 2000-09-11DOI: 10.1109/OCEANS.2000.881235
B. Fletcher
At the request of the Assistant Secretary of the Navy for Research, Development and Acquisition (ASN-RDA), The Navy Unmanned Undersea Vehicle (UUV) Master Plan was prepared, outlining recommended development pathways for UUV systems and technologies for the next decade and beyond. An overall vision of UUVs as integral parts of the battle force is portrayed with four signature capabilities seen as critical to both near term and long term goals. The Maritime Reconnaissance capability provides the means of gathering information from designated areas in a timely and covert manner. Undersea Search and Survey serves both the need for tactical oceanographic data and mine reconnaissance/neutralization. UUVs can also be employed as Navigation/Communication Aids, providing valuable connectivity in the realm of network-centric warfare. Finally, Submarine Track and Trail will provide new capabilities for target engagement. The technologies required to accomplish these missions were surveyed, and a programmatic roadmap was prepared to develop those capabilities determined to be on the critical paths for implementation.
{"title":"UUV master plan: a vision for navy UUV development","authors":"B. Fletcher","doi":"10.1109/OCEANS.2000.881235","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881235","url":null,"abstract":"At the request of the Assistant Secretary of the Navy for Research, Development and Acquisition (ASN-RDA), The Navy Unmanned Undersea Vehicle (UUV) Master Plan was prepared, outlining recommended development pathways for UUV systems and technologies for the next decade and beyond. An overall vision of UUVs as integral parts of the battle force is portrayed with four signature capabilities seen as critical to both near term and long term goals. The Maritime Reconnaissance capability provides the means of gathering information from designated areas in a timely and covert manner. Undersea Search and Survey serves both the need for tactical oceanographic data and mine reconnaissance/neutralization. UUVs can also be employed as Navigation/Communication Aids, providing valuable connectivity in the realm of network-centric warfare. Finally, Submarine Track and Trail will provide new capabilities for target engagement. The technologies required to accomplish these missions were surveyed, and a programmatic roadmap was prepared to develop those capabilities determined to be on the critical paths for implementation.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"95 1","pages":"65-71 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79548851","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}
Pub Date : 2000-09-11DOI: 10.1109/OCEANS.2000.882237
H. K. Yeo, B. Sharif, A. Adams, O. Hinton
This paper describes the testing of an experimental water acoustic network communication that was conducted at the North Sea, Netherlands. The North Sea is a shallow channel that exhibits multipath propagation that results in signal fading and phase fluctuations at the receiver. The Doppler effect is another phenomenon that is observed due the movement of both the source and the receiver that is caused either by the swelling of the wave fronts or the mechanical movement of the source. Sources of background noise are highly variable from a mixture of environmental and man-made noises. Situations of multiuser paths with range to depth ratio of 28:1 and 277:1 respectively are examined and the results from the experimental data are then compared to a simulated theoretical model. The simulated channel is characterized by using ray theory and extending it to a multipath expansion for a series of reflections resulting in multipath arrival at the receiver.
{"title":"Analysis of experimental shallow water network channel and theoretical channel model","authors":"H. K. Yeo, B. Sharif, A. Adams, O. Hinton","doi":"10.1109/OCEANS.2000.882237","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.882237","url":null,"abstract":"This paper describes the testing of an experimental water acoustic network communication that was conducted at the North Sea, Netherlands. The North Sea is a shallow channel that exhibits multipath propagation that results in signal fading and phase fluctuations at the receiver. The Doppler effect is another phenomenon that is observed due the movement of both the source and the receiver that is caused either by the swelling of the wave fronts or the mechanical movement of the source. Sources of background noise are highly variable from a mixture of environmental and man-made noises. Situations of multiuser paths with range to depth ratio of 28:1 and 277:1 respectively are examined and the results from the experimental data are then compared to a simulated theoretical model. The simulated channel is characterized by using ray theory and extending it to a multipath expansion for a series of reflections resulting in multipath arrival at the receiver.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"30 1","pages":"2025-2029 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90732222","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}
Pub Date : 2000-09-11DOI: 10.1109/OCEANS.2000.881282
M. Bowen, P. J. Bernard, D. Gleason, L. Whitcomb
Sample recovery devices have been fabricated for use with the Jason deep diving remotely operated vehicle (ROV). They are custom-built, autonomous vertical transporters (AVTs) that are capable of raising numerous benthic samples and other payloads to the ocean's surface independent of the sampling ROV. AVTs are more commonly referred to as sample "elevators". Elevators are inexpensive to construct and can be deployed and recovered many times during the course of a single ROV dive in order to reduce wear and tear on the more expensive ROV. This paper describes the design, fabrication, operation and navigational tracking of these 6,000 meter rated, nondestructive benthic sample transportation vehicles.
{"title":"Elevators-autonomous transporters for deepsea benthic sample recovery","authors":"M. Bowen, P. J. Bernard, D. Gleason, L. Whitcomb","doi":"10.1109/OCEANS.2000.881282","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881282","url":null,"abstract":"Sample recovery devices have been fabricated for use with the Jason deep diving remotely operated vehicle (ROV). They are custom-built, autonomous vertical transporters (AVTs) that are capable of raising numerous benthic samples and other payloads to the ocean's surface independent of the sampling ROV. AVTs are more commonly referred to as sample \"elevators\". Elevators are inexpensive to construct and can be deployed and recovered many times during the course of a single ROV dive in order to reduce wear and tear on the more expensive ROV. This paper describes the design, fabrication, operation and navigational tracking of these 6,000 meter rated, nondestructive benthic sample transportation vehicles.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"92 4 1","pages":"343-348 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89451025","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}
Pub Date : 2000-09-11DOI: 10.1109/OCEANS.2000.882160
Hsin-Hung Chen, Chia-Ju Lee
This paper presents a video system for underwater range finding and target tracking. The method depends on geometrical triangulation using a video camera, a laser diode, and an object plane. This system, which is completely controlled by a personal computer, provides excellent capabilities of efficient calibration and accurate range data processing. Through the calculation of the intensity center of the laser spot, we refine the performance of measurement up to subpixel accuracy. This system employs polynomial interpolation to calibrate the measurement error resulting from geometrical distortion and lens aberrations. The results show that the system can produce excellent accuracy for range finding and target tracking both in air and underwater.
{"title":"A simple underwater video system for laser tracking","authors":"Hsin-Hung Chen, Chia-Ju Lee","doi":"10.1109/OCEANS.2000.882160","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.882160","url":null,"abstract":"This paper presents a video system for underwater range finding and target tracking. The method depends on geometrical triangulation using a video camera, a laser diode, and an object plane. This system, which is completely controlled by a personal computer, provides excellent capabilities of efficient calibration and accurate range data processing. Through the calculation of the intensity center of the laser spot, we refine the performance of measurement up to subpixel accuracy. This system employs polynomial interpolation to calibrate the measurement error resulting from geometrical distortion and lens aberrations. The results show that the system can produce excellent accuracy for range finding and target tracking both in air and underwater.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"98 1","pages":"1543-1548 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90810928","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}
Pub Date : 2000-09-11DOI: 10.1109/OCEANS.2000.882224
R. Hosoda, T. Nomura, K. Yamaguchi, B. Murata
The authors propose the concept of an "Eco-Platform", setting their sight on solving problems that have arisen/arise/will arise around the coastal areas and on the restoration of natural environments of the world as a final goal. The Eco-Platform is a floating platform on which facilities are installed to dispose waste and sewage from land area, to generate heat/electric energy, to reproduce industrial resources/materials from discharged waste and sewage and to purify eutrophic sea water and contaminated sea bottom sediment. All the facilities and functions are integrated systematically to achieve no fossil energy introduction, cascade use of heat energy, efficient use of low-energy heat energy for applying marine bio-technology, and to achieve the zero-emission principle. No new technologies are required to be developed for achieving the Eco-Platform. Some fundamental functions of the system have been studied for the realization of the Eco-Platform.
{"title":"Concept of Eco-Platform","authors":"R. Hosoda, T. Nomura, K. Yamaguchi, B. Murata","doi":"10.1109/OCEANS.2000.882224","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.882224","url":null,"abstract":"The authors propose the concept of an \"Eco-Platform\", setting their sight on solving problems that have arisen/arise/will arise around the coastal areas and on the restoration of natural environments of the world as a final goal. The Eco-Platform is a floating platform on which facilities are installed to dispose waste and sewage from land area, to generate heat/electric energy, to reproduce industrial resources/materials from discharged waste and sewage and to purify eutrophic sea water and contaminated sea bottom sediment. All the facilities and functions are integrated systematically to achieve no fossil energy introduction, cascade use of heat energy, efficient use of low-energy heat energy for applying marine bio-technology, and to achieve the zero-emission principle. No new technologies are required to be developed for achieving the Eco-Platform. Some fundamental functions of the system have been studied for the realization of the Eco-Platform.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"1 1","pages":"1943-1949 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91316467","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}
Pub Date : 2000-09-11DOI: 10.1109/OCEANS.2000.881728
S. Baglio, C. Faraci, E. Foti, R. Musumeci
A novel three-dimensional measurement technique which uses a stereo vision approach to recover the morphological evolution of a sandy bottom around a vertical pile is presented. In particular, the bottom time evolution due to the wave action was observed from the initial flat bed condition until a stable configuration was attained. Moreover, some morphological parameters of the scour, such as the maximum scour depth, the extension of the eroded area and the position of the maximum scour toe, were measured at equilibrium condition. These quantities were estimated with an average relative accuracy of about five percent, which appears particularly appropriate if compared to the results given by traditional measurement strategies. The key parameter which controls the phenomenon is the Keulegan-Carpenter number (KC). The experimental measures of the scour depth at equilibrium stage were compared with the empirical relations proposed by Sumer et al. (1992) giving a fairly good agreement, while for other three-dimensional features, such as the eroded area, new relations with typical dimensionless parameters useful for design purposes are proposed.
{"title":"Stereo vision for noninvasive dynamic measurements of the scour process around a circular cylinder in an oscillating flow","authors":"S. Baglio, C. Faraci, E. Foti, R. Musumeci","doi":"10.1109/OCEANS.2000.881728","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881728","url":null,"abstract":"A novel three-dimensional measurement technique which uses a stereo vision approach to recover the morphological evolution of a sandy bottom around a vertical pile is presented. In particular, the bottom time evolution due to the wave action was observed from the initial flat bed condition until a stable configuration was attained. Moreover, some morphological parameters of the scour, such as the maximum scour depth, the extension of the eroded area and the position of the maximum scour toe, were measured at equilibrium condition. These quantities were estimated with an average relative accuracy of about five percent, which appears particularly appropriate if compared to the results given by traditional measurement strategies. The key parameter which controls the phenomenon is the Keulegan-Carpenter number (KC). The experimental measures of the scour depth at equilibrium stage were compared with the empirical relations proposed by Sumer et al. (1992) giving a fairly good agreement, while for other three-dimensional features, such as the eroded area, new relations with typical dimensionless parameters useful for design purposes are proposed.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"33 1 1","pages":"987-992 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90451098","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}
Pub Date : 2000-09-11DOI: 10.1109/OCEANS.2000.881814
D.M. Deveau
The need for calibrated sonar targets is addressed in connection with the development and testing of a set of thin-walled spheres filled with a high-density fluid. Using historical research information as a guide, a set of thin-walled metal spheres was developed and filled with a high-density fluid. The combination of the spherical shape and the acoustic focusing effects of the fluid enhanced the acoustic target strength of the shape so that it was not only stable with temperature but also significantly greater in amplitude. The simple passive nature of the spheres makes them ideal acoustic targets for long-term, unattended deployments.
{"title":"Fabrication, testing, and installation of fluid-filled target spheres for AUTEC's passive sonar calibration system","authors":"D.M. Deveau","doi":"10.1109/OCEANS.2000.881814","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881814","url":null,"abstract":"The need for calibrated sonar targets is addressed in connection with the development and testing of a set of thin-walled spheres filled with a high-density fluid. Using historical research information as a guide, a set of thin-walled metal spheres was developed and filled with a high-density fluid. The combination of the spherical shape and the acoustic focusing effects of the fluid enhanced the acoustic target strength of the shape so that it was not only stable with temperature but also significantly greater in amplitude. The simple passive nature of the spheres makes them ideal acoustic targets for long-term, unattended deployments.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"3 1","pages":"1481-1487 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76771810","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}
Pub Date : 2000-09-11DOI: 10.1109/OCEANS.2000.881760
A. Williams, E. Terray
Directional wave spectra, valuable to describe the sea-state, can be computed as the correlation of horizontal velocity with pressure measured at a single point. Pressure was used instead of the vertical component of velocity for the correlation since the deployment height of 70 cm above the bottom attenuated the vertical wave velocity component. A Modular Acoustic Velocity Sensor (MAVS) with integral pressure sensor was deployed on the bottom in 10 meters depth in Buzzards Bay, Massachusetts during February 2000 in conjunction with the ASIS Multi-Spar Buoy, providing surface wave measurements, and other wave sensing instruments. MAVS was attached to a bracket on the corner of a sled resting on the bottom that contained a fan beam Acoustic Doppler Current Profiler (ADCP) for measurement of directional wave spectra from beneath the surface. The purpose of the experiment was to observe fetch-limited waves. The deployment site, near Nye Ledge, is about 7 km from shore in all directions except southwest. Waves with periods ranging from 5 to 12 seconds were measured propagating north to northeast when strong winds blew from the southwest. Velocities and pressure were sampled at 1.4 Hz for 14 minutes every 4 hours. The observations of velocity were corrected for tilt and compass orientation of the sensor and stored as Cartesian components of velocity along with digitized output of a 20 decibar Omega pressure sensor. Although the deployment of the instrument was 25 days, the data record from MAVS was limited to 15 days by battery and data capacity. This technique of directional wave spectral measurement from a simple vector current meter with pressure sensor demonstrates a capability that can be used in moored arrays for wave refraction studies over topography or for shoaling waves and fetch limited waves as a function of distance from the shore. The low cost of the instrument used in this experiment permits such an array to be deployed with moderate cost.
{"title":"Measurement of directional wave spectrum with a modular acoustic velocity sensor","authors":"A. Williams, E. Terray","doi":"10.1109/OCEANS.2000.881760","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881760","url":null,"abstract":"Directional wave spectra, valuable to describe the sea-state, can be computed as the correlation of horizontal velocity with pressure measured at a single point. Pressure was used instead of the vertical component of velocity for the correlation since the deployment height of 70 cm above the bottom attenuated the vertical wave velocity component. A Modular Acoustic Velocity Sensor (MAVS) with integral pressure sensor was deployed on the bottom in 10 meters depth in Buzzards Bay, Massachusetts during February 2000 in conjunction with the ASIS Multi-Spar Buoy, providing surface wave measurements, and other wave sensing instruments. MAVS was attached to a bracket on the corner of a sled resting on the bottom that contained a fan beam Acoustic Doppler Current Profiler (ADCP) for measurement of directional wave spectra from beneath the surface. The purpose of the experiment was to observe fetch-limited waves. The deployment site, near Nye Ledge, is about 7 km from shore in all directions except southwest. Waves with periods ranging from 5 to 12 seconds were measured propagating north to northeast when strong winds blew from the southwest. Velocities and pressure were sampled at 1.4 Hz for 14 minutes every 4 hours. The observations of velocity were corrected for tilt and compass orientation of the sensor and stored as Cartesian components of velocity along with digitized output of a 20 decibar Omega pressure sensor. Although the deployment of the instrument was 25 days, the data record from MAVS was limited to 15 days by battery and data capacity. This technique of directional wave spectral measurement from a simple vector current meter with pressure sensor demonstrates a capability that can be used in moored arrays for wave refraction studies over topography or for shoaling waves and fetch limited waves as a function of distance from the shore. The low cost of the instrument used in this experiment permits such an array to be deployed with moderate cost.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"16 1","pages":"1175-1180 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76957954","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}
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