中国会展 Pub Date : 2000-09-11 DOI: 10.1109/OCEANS.2000.882204

K. Kebkal, R. Bannasch

{"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}

引用次数: 7

Recent advances in thin, low frequency acoustic projectors 薄型低频声学投影仪的最新进展

中国会展 Pub Date : 2000-09-11 DOI: 10.1109/OCEANS.2000.881813

T. Howarth, J. Tressler

引用次数: 3

UUV master plan: a vision for navy UUV development UUV总体规划:海军UUV发展愿景

中国会展 Pub Date : 2000-09-11 DOI: 10.1109/OCEANS.2000.881235

B. Fletcher

引用次数: 55

Analysis of experimental shallow water network channel and theoretical channel model 实验浅水网河道分析与理论河道模型

中国会展 Pub Date : 2000-09-11 DOI: 10.1109/OCEANS.2000.882237

H. K. Yeo, B. Sharif, A. Adams, O. Hinton

引用次数: 5

Elevators-autonomous transporters for deepsea benthic sample recovery 升降机——深海底栖生物样本回收的自主运输工具

中国会展 Pub Date : 2000-09-11 DOI: 10.1109/OCEANS.2000.881282

M. Bowen, P. J. Bernard, D. Gleason, L. Whitcomb

引用次数: 4

A simple underwater video system for laser tracking 一个简单的水下视频系统用于激光跟踪

中国会展 Pub Date : 2000-09-11 DOI: 10.1109/OCEANS.2000.882160

Hsin-Hung Chen, Chia-Ju Lee

引用次数: 11

Concept of Eco-Platform 生态平台概念

中国会展 Pub Date : 2000-09-11 DOI: 10.1109/OCEANS.2000.882224

R. Hosoda, T. Nomura, K. Yamaguchi, B. Murata

引用次数: 1

Stereo vision for noninvasive dynamic measurements of the scour process around a circular cylinder in an oscillating flow 立体视觉在振荡流中对圆柱冲刷过程的无创动态测量

中国会展 Pub Date : 2000-09-11 DOI: 10.1109/OCEANS.2000.881728

S. Baglio, C. Faraci, E. Foti, R. Musumeci

{"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}

引用次数: 7

Fabrication, testing, and installation of fluid-filled target spheres for AUTEC's passive sonar calibration system AUTEC被动声纳校准系统充液靶球的制造、测试和安装

中国会展 Pub Date : 2000-09-11 DOI: 10.1109/OCEANS.2000.881814

D.M. Deveau

引用次数: 4

Measurement of directional wave spectrum with a modular acoustic velocity sensor 用模块化声速传感器测量定向波谱

中国会展 Pub Date : 2000-09-11 DOI: 10.1109/OCEANS.2000.881760

A. Williams, E. Terray

{"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}

引用次数: 8

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