Pub Date : 2004-06-15DOI: 10.1109/OCEANS.2002.1191898
T. Pedersen, S. Nylund, A. Dolle
Nortek has improved upon its AWAC, a current and wave measurement sensor package, by introducing a vertical, acoustic beam that detects the surface. This added functionality allows for directly measuring waves as opposed to interfering wave estimates from wave energy spectra. Traditionally, wave measurements from bottom-mounted instruments, such as the combine pressure-velocity (PUV) approach, are limited in their frequency response. This is due to attenuation of the surface signal with increasing depth. Recent advances employ the alternative solution of measuring orbital velocities close to the surface and incorporating the Maximum Likelihood Method (MLM) estimate technique (Krogstad et al., 1988). This improves the accuracy at higher frequencies. However, for deployment depths of 10 metres or deeper, these methods cannot resolve waves periods that are 3 seconds or shorter. Moreover, these bottom-mounted systems do not measure the real surface time series, which makes it difficult to calculate extreme value statistics. The following paper provides an overview of the process of (1) developing the surface track algorithms, (2) comparing with a Datawell wave buoy off the coast of Carqueirance, France (3) and testing limiting conditions such as breaking waves and greater depths (35 metres).
Nortek公司对AWAC进行了改进，AWAC是一种电流和波浪测量传感器套件，通过引入垂直声束来检测表面。这种增加的功能允许直接测量波浪，而不是从波浪能量谱中进行干扰波估计。传统上，通过底部安装的仪器进行波浪测量，例如组合压力-速度(PUV)方法，其频率响应受到限制。这是由于地表信号随着深度的增加而衰减。最近的进展采用了另一种解决方案，即测量靠近地表的轨道速度，并结合最大似然法(MLM)估计技术(Krogstad et al.， 1988)。这提高了更高频率下的精度。然而，对于10米或更深的部署深度，这些方法无法解析3秒或更短的波周期。此外，这些底部安装的系统不测量真实的地表时间序列，这使得极值统计的计算变得困难。下面的论文概述了(1)开发水面跟踪算法的过程，(2)与法国Carqueirance海岸的Datawell波浪浮标进行比较(3)并测试极限条件，如破浪和更大的深度(35米)。
{"title":"Wave height measurements using acoustic surface tracking","authors":"T. Pedersen, S. Nylund, A. Dolle","doi":"10.1109/OCEANS.2002.1191898","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1191898","url":null,"abstract":"Nortek has improved upon its AWAC, a current and wave measurement sensor package, by introducing a vertical, acoustic beam that detects the surface. This added functionality allows for directly measuring waves as opposed to interfering wave estimates from wave energy spectra. Traditionally, wave measurements from bottom-mounted instruments, such as the combine pressure-velocity (PUV) approach, are limited in their frequency response. This is due to attenuation of the surface signal with increasing depth. Recent advances employ the alternative solution of measuring orbital velocities close to the surface and incorporating the Maximum Likelihood Method (MLM) estimate technique (Krogstad et al., 1988). This improves the accuracy at higher frequencies. However, for deployment depths of 10 metres or deeper, these methods cannot resolve waves periods that are 3 seconds or shorter. Moreover, these bottom-mounted systems do not measure the real surface time series, which makes it difficult to calculate extreme value statistics. The following paper provides an overview of the process of (1) developing the surface track algorithms, (2) comparing with a Datawell wave buoy off the coast of Carqueirance, France (3) and testing limiting conditions such as breaking waves and greater depths (35 metres).","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131210894","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 : 2002-12-01DOI: 10.1109/OCEANS.2002.1191836
C. Tiemann, M. B. Porter, J. Hildebrand
In a previous work, we developed an algorithm for acoustically tracking singing humpback whales near Hawaii. Pair-wise time-differences in arrival of whale calls as measured by a phase-only correlation process are compared to time-lags predicted by an acoustic propagation model. Differences between measured and modeled time-lags defined an ambiguity surface that identifies the most probable whale location in a horizontal plane around an array. In this work, we describe the application of this technique to a very different environmental scenario involving blue whales off the coast of California. The whale calls are much lower in frequency and the receivers are ocean bottom seismometers. Again the algorithm performs extremely well, providing the capability for real-time, automated monitoring and alert.
{"title":"Automated model-based localization of marine mammals near California","authors":"C. Tiemann, M. B. Porter, J. Hildebrand","doi":"10.1109/OCEANS.2002.1191836","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1191836","url":null,"abstract":"In a previous work, we developed an algorithm for acoustically tracking singing humpback whales near Hawaii. Pair-wise time-differences in arrival of whale calls as measured by a phase-only correlation process are compared to time-lags predicted by an acoustic propagation model. Differences between measured and modeled time-lags defined an ambiguity surface that identifies the most probable whale location in a horizontal plane around an array. In this work, we describe the application of this technique to a very different environmental scenario involving blue whales off the coast of California. The whale calls are much lower in frequency and the receivers are ocean bottom seismometers. Again the algorithm performs extremely well, providing the capability for real-time, automated monitoring and alert.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115460079","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 : 2002-12-01DOI: 10.1109/OCEANS.2002.1193327
H. Seim, Francisco E. Werner, M. Fletcher, J. Nelson, R. Jahnke, C. Mooers, Lynn K. Shay, R. Weisberg, Mark E. Luther
The SEA-COOS initiative is an eleven-institution collaboration to begin development of a regional coastal ocean observing system for the southeast (North and South Carolina, Georgia, Florida) United States. A three-pronged program of observing, modeling, and data management will be established while simultaneously conducting outreach studies of user needs and exploring governance models for the program in future years. Details of the program specifics are given.
{"title":"SEA-COOS: Southeast Atlantic Coastal Ocean Observing System","authors":"H. Seim, Francisco E. Werner, M. Fletcher, J. Nelson, R. Jahnke, C. Mooers, Lynn K. Shay, R. Weisberg, Mark E. Luther","doi":"10.1109/OCEANS.2002.1193327","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1193327","url":null,"abstract":"The SEA-COOS initiative is an eleven-institution collaboration to begin development of a regional coastal ocean observing system for the southeast (North and South Carolina, Georgia, Florida) United States. A three-pronged program of observing, modeling, and data management will be established while simultaneously conducting outreach studies of user needs and exploring governance models for the program in future years. Details of the program specifics are given.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124713362","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 : 2002-12-01DOI: 10.1109/OCEANS.2002.1191860
T. Campbell, J. Cazes, E. Rogers
SWAN (Simulating WAves Nearshore), developed at the Delft University of Technology, is an important third generation wave model used to simulate short-crested wind-generated waves in shallow water areas such as coastal regions and inland waters. The model solves a four-dimensional (2 spatial dimensions, wave direction, and wave frequency) spectral action balance equation using a semi-implicit upwind scheme. Relative to other less advanced wave models, SWAN is more computationally demanding, and a parallel version is necessary in order to decrease turn-around time, improve the model resolution for large coastal regions, and migrate SWAN into Navy operational use. In this paper we present a new parallel implementation of SWAN using a pipelined parallel approach which does not alter the order of operations in the sequential numerical algorithm. The implementation uses OpenMP compiler directives and runs on shared-memory multiprocessor computers. This approach represents a non-traditional, i.e., not loop-level, way of using OpenMP. Performance measurements show that turn-around time for high-resolution model applications can be significantly reduced with the parallel implementation. The parallel implementation has been verified and model output matches "bit-for-bit" with the original sequential code for both stationary and non-stationary cases. The new parallel code has already been incorporated into the next official release of SWAN and is beginning transition into operational use.
{"title":"Implementation of an important wave model on parallel architectures","authors":"T. Campbell, J. Cazes, E. Rogers","doi":"10.1109/OCEANS.2002.1191860","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1191860","url":null,"abstract":"SWAN (Simulating WAves Nearshore), developed at the Delft University of Technology, is an important third generation wave model used to simulate short-crested wind-generated waves in shallow water areas such as coastal regions and inland waters. The model solves a four-dimensional (2 spatial dimensions, wave direction, and wave frequency) spectral action balance equation using a semi-implicit upwind scheme. Relative to other less advanced wave models, SWAN is more computationally demanding, and a parallel version is necessary in order to decrease turn-around time, improve the model resolution for large coastal regions, and migrate SWAN into Navy operational use. In this paper we present a new parallel implementation of SWAN using a pipelined parallel approach which does not alter the order of operations in the sequential numerical algorithm. The implementation uses OpenMP compiler directives and runs on shared-memory multiprocessor computers. This approach represents a non-traditional, i.e., not loop-level, way of using OpenMP. Performance measurements show that turn-around time for high-resolution model applications can be significantly reduced with the parallel implementation. The parallel implementation has been verified and model output matches \"bit-for-bit\" with the original sequential code for both stationary and non-stationary cases. The new parallel code has already been incorporated into the next official release of SWAN and is beginning transition into operational use.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"121 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114569792","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 : 2002-12-01DOI: 10.1109/OCEANS.2002.1191887
S. Glenn, O. Schofield
The New Jersey Shelf Observing System is a coastal ocean observatory whose primary goal is supporting collaborative interdisciplinary oceanographic research. The observatory has both a sustained component designed to provide spatial datasets year-round, and a process study component for more intensive measurements during short-term scientific experiments. The sustained component consists of tracking stations for the international constellation of ocean color and IR satellites, multi-frequency multistatic CODAR HF radars, and long-duration subsurface glider AUVs. The processes study component uses numerous platforms that include aircraft, ships, propeller-driven AUVs and relocatable mooring arrays. Process studies focused on recurrent coastal upwelling centers and their biological impacts from 1998-2001, and are planned to focus on the Hudson River plume, chemical contaminants, and their biological impacts from 2003-2007. Despite being a research-oriented observatory run by the scientists for the scientists, it maintains a significant societal impact through its Website (marine.rutgers.edu/cool), receiving an average of over 60,000 hits/day during the busy summer months.
{"title":"The New Jersey Shelf Observing System","authors":"S. Glenn, O. Schofield","doi":"10.1109/OCEANS.2002.1191887","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1191887","url":null,"abstract":"The New Jersey Shelf Observing System is a coastal ocean observatory whose primary goal is supporting collaborative interdisciplinary oceanographic research. The observatory has both a sustained component designed to provide spatial datasets year-round, and a process study component for more intensive measurements during short-term scientific experiments. The sustained component consists of tracking stations for the international constellation of ocean color and IR satellites, multi-frequency multistatic CODAR HF radars, and long-duration subsurface glider AUVs. The processes study component uses numerous platforms that include aircraft, ships, propeller-driven AUVs and relocatable mooring arrays. Process studies focused on recurrent coastal upwelling centers and their biological impacts from 1998-2001, and are planned to focus on the Hudson River plume, chemical contaminants, and their biological impacts from 2003-2007. Despite being a research-oriented observatory run by the scientists for the scientists, it maintains a significant societal impact through its Website (marine.rutgers.edu/cool), receiving an average of over 60,000 hits/day during the busy summer months.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114828407","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 : 2002-12-01DOI: 10.1109/OCEANS.2002.1191973
Hee-Young Park, W. Oh, D. Youn, Chungyong Lee
This paper proposes a subspace-based array shape estimation method using a single reference source in nearfield. First, from the nearfield source received by hydrophones, setting the degree of freedom of the perturbation equal to one, a nearfield covariance matrix is derived. Second, a simplified subspace fitting method that requires only a single reference source is proposed. From the numerical experiments, the proposed method shows good performance in estimating the shape of the array using only a single reference source wherever the source exists.
{"title":"A subspace-based array shape estimation method using a single reference source in nearfield","authors":"Hee-Young Park, W. Oh, D. Youn, Chungyong Lee","doi":"10.1109/OCEANS.2002.1191973","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1191973","url":null,"abstract":"This paper proposes a subspace-based array shape estimation method using a single reference source in nearfield. First, from the nearfield source received by hydrophones, setting the degree of freedom of the perturbation equal to one, a nearfield covariance matrix is derived. Second, a simplified subspace fitting method that requires only a single reference source is proposed. From the numerical experiments, the proposed method shows good performance in estimating the shape of the array using only a single reference source wherever the source exists.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131604757","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 : 2002-10-31DOI: 10.1109/OCEANS.2002.1191952
D. Tang, K. Williams, E.I. Thoros, K. Briggs
It is critical for buried target detection via ripple scattering to know the ripple structure, e.g., the ripple height and spatial wavelength. In the present paper, backscattering data from a 300-kHz system show that ripple wavelength and height can potentially be estimated from backscattering images. Motivated by the backscatter data, we have developed a time-domain numerical model to simulate scattering of high-frequency sound by a ripple field. This model treats small-scale scatterers as Lambertian scatterers distributed randomly on the large-scale ripple field. We have found that this approach characterizes the field data well. Numerical simulations are conducted to investigate the possibility of remotely sensing bottom ripple heights and wavelength.
{"title":"Remote sensing of sand ripples using high-frequency backscatter","authors":"D. Tang, K. Williams, E.I. Thoros, K. Briggs","doi":"10.1109/OCEANS.2002.1191952","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1191952","url":null,"abstract":"It is critical for buried target detection via ripple scattering to know the ripple structure, e.g., the ripple height and spatial wavelength. In the present paper, backscattering data from a 300-kHz system show that ripple wavelength and height can potentially be estimated from backscattering images. Motivated by the backscatter data, we have developed a time-domain numerical model to simulate scattering of high-frequency sound by a ripple field. This model treats small-scale scatterers as Lambertian scatterers distributed randomly on the large-scale ripple field. We have found that this approach characterizes the field data well. Numerical simulations are conducted to investigate the possibility of remotely sensing bottom ripple heights and wavelength.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"24 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123701042","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 : 2002-10-31DOI: 10.1109/OCEANS.2002.1191858
M. Cobb, C. Blain
Because tidal inlets are important areas with respect to biodiversity, sediment transport, freshwater river outflow, and pollutant transport, a comprehensive understanding of their circulation patterns is necessary for their management. This study focuses on modeling the 2D, depth-averaged circulation of Bay St. Louis in the northeastern Gulf of Mexico that is driven by waves and tides using a coupled hydrodynamic-wave model. The wave-tide coupled circulation within the inlet is examined during the flood, slack, and ebb phases of the tidal cycle. The wave height field, current velocity and sea surface elevation are analyzed to determine the effects of wave-current interaction. The influence of the various forcings on bay/inlet circulation is further investigated by the introduction of Lagrangian tracers. Lagrangian tracers are a reasonable indicator of how circulation patterns affect the motion of sediment particles or passive biological organisms such as fish larvae. Wave-current interaction is simulated by iteratively coupling the depth-integrated ADCIRC-2DDI hydrodynamic model to the phase-averaged spectral wave model SWAN. ADCIRC-2DDI is a fully developed, 2-dimensional, finite element, barotropic hydrodynamic model capable o f including wind, wave, and tidal forcing as well as river flux into the domain. The wave-hydrodynamic model coupling is captured through the following approach. First, radiation stress gradients, determined from the SWAN wave field, serve as surface stress forcing in ADCIRC. Elevation and currents computed from ADCIRC are subsequently input into the SWAN model. Between these iterations, the ADCIRC model is run for some appropriately small time interval during which the wave field is held constant. Presently there are no shelf-scale hydrodynamic models that incorporate waves, therefore a coupled model approach is one way of simulating wave-current interaction in bays and inlets. This approach is very flexible, making it possible to couple different wave models to ADCIRC depending on the relevant physics of the domain being studied (e.g. monochromatic wave diffraction vs. multi-spectral wave effects).
{"title":"Simulating wave-tide induced circulation in Bay St. Louis, MS with a coupled hydrodynamic-wave model","authors":"M. Cobb, C. Blain","doi":"10.1109/OCEANS.2002.1191858","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1191858","url":null,"abstract":"Because tidal inlets are important areas with respect to biodiversity, sediment transport, freshwater river outflow, and pollutant transport, a comprehensive understanding of their circulation patterns is necessary for their management. This study focuses on modeling the 2D, depth-averaged circulation of Bay St. Louis in the northeastern Gulf of Mexico that is driven by waves and tides using a coupled hydrodynamic-wave model. The wave-tide coupled circulation within the inlet is examined during the flood, slack, and ebb phases of the tidal cycle. The wave height field, current velocity and sea surface elevation are analyzed to determine the effects of wave-current interaction. The influence of the various forcings on bay/inlet circulation is further investigated by the introduction of Lagrangian tracers. Lagrangian tracers are a reasonable indicator of how circulation patterns affect the motion of sediment particles or passive biological organisms such as fish larvae. Wave-current interaction is simulated by iteratively coupling the depth-integrated ADCIRC-2DDI hydrodynamic model to the phase-averaged spectral wave model SWAN. ADCIRC-2DDI is a fully developed, 2-dimensional, finite element, barotropic hydrodynamic model capable o f including wind, wave, and tidal forcing as well as river flux into the domain. The wave-hydrodynamic model coupling is captured through the following approach. First, radiation stress gradients, determined from the SWAN wave field, serve as surface stress forcing in ADCIRC. Elevation and currents computed from ADCIRC are subsequently input into the SWAN model. Between these iterations, the ADCIRC model is run for some appropriately small time interval during which the wave field is held constant. Presently there are no shelf-scale hydrodynamic models that incorporate waves, therefore a coupled model approach is one way of simulating wave-current interaction in bays and inlets. This approach is very flexible, making it possible to couple different wave models to ADCIRC depending on the relevant physics of the domain being studied (e.g. monochromatic wave diffraction vs. multi-spectral wave effects).","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123073207","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 : 2002-10-31DOI: 10.1109/OCEANS.2002.1193250
S. Griffin, J. Bradley, M. Thiele, C. Tran, F. Grosz, M. Richardson
Detection of buried mines using conventional sonars is difficult, especially in complex coastal environments, which complicates naval tactical decisions such as whether to hunt, sweep, or avoid a mined area. The US Navy is therefore supporting research to develop and validate stochastic, time-dependent, mine burial prediction models. This research requires continuous monitoring of both mine behavior during burial and the near-field processes responsible for burial. Modes of burial are generally separated into two broad categories: impact burial and subsequent burial (scour and fill, creep, liquefaction, and bedform modification). Omni Technologies, Inc. (OTI) and the Naval Research Laboratory (NRL) have developed instrumented mines that measure both subsequent mine burial behavior and the processes that initiate and effect burial. In this paper we describe new instrumented mines, including acoustic sensors used to measure burial and sensors used to measure mine orientation, azimuth and movement. Sensors and methods used to measure characteristics of surface gravity waves, direction and magnitude of bottom currents, turbulent flow near the mine, initiation of bedload motion, and sediment size and concentration in the water column are also described.
{"title":"An improved subsequent burial instrumented mine","authors":"S. Griffin, J. Bradley, M. Thiele, C. Tran, F. Grosz, M. Richardson","doi":"10.1109/OCEANS.2002.1193250","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1193250","url":null,"abstract":"Detection of buried mines using conventional sonars is difficult, especially in complex coastal environments, which complicates naval tactical decisions such as whether to hunt, sweep, or avoid a mined area. The US Navy is therefore supporting research to develop and validate stochastic, time-dependent, mine burial prediction models. This research requires continuous monitoring of both mine behavior during burial and the near-field processes responsible for burial. Modes of burial are generally separated into two broad categories: impact burial and subsequent burial (scour and fill, creep, liquefaction, and bedform modification). Omni Technologies, Inc. (OTI) and the Naval Research Laboratory (NRL) have developed instrumented mines that measure both subsequent mine burial behavior and the processes that initiate and effect burial. In this paper we describe new instrumented mines, including acoustic sensors used to measure burial and sensors used to measure mine orientation, azimuth and movement. Sensors and methods used to measure characteristics of surface gravity waves, direction and magnitude of bottom currents, turbulent flow near the mine, initiation of bedload motion, and sediment size and concentration in the water column are also described.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122196620","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 : 2002-10-29DOI: 10.1109/OCEANS.2002.1191974
Y. Son, Ki-Man Kim, Seung-Yong Chun, W. Oh
In this paper, we present a method to get the optimized beampattern for line array with faulty elements. The faulty element means the sensor that has no output or highly reduced gain than other normal sensors. It is not easy to form the ideal beam in unstable undersea environments. In the case of faulty elements, the average sidelobe level on beampattern is higher. And the faulty elements generate the distorted beampattern. So we propose the method to compensate the distorted beampattern. The proposed method calculates the weights to minimize the squared error between the ideal pattern and the distorted pattern. And the criteria have a constraint about faulty elements. The performance of the proposed method was evaluated via computer simulation under various environments.
{"title":"Pattern optimization for line array with faulty elements","authors":"Y. Son, Ki-Man Kim, Seung-Yong Chun, W. Oh","doi":"10.1109/OCEANS.2002.1191974","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1191974","url":null,"abstract":"In this paper, we present a method to get the optimized beampattern for line array with faulty elements. The faulty element means the sensor that has no output or highly reduced gain than other normal sensors. It is not easy to form the ideal beam in unstable undersea environments. In the case of faulty elements, the average sidelobe level on beampattern is higher. And the faulty elements generate the distorted beampattern. So we propose the method to compensate the distorted beampattern. The proposed method calculates the weights to minimize the squared error between the ideal pattern and the distorted pattern. And the criteria have a constraint about faulty elements. The performance of the proposed method was evaluated via computer simulation under various environments.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"153 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124284996","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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