Pub Date : 2000-09-11DOI: 10.1109/OCEANS.2000.882212
E. J. Brandreth
The author describes what today's modern airship, "blimp", can offer to those wishing to have an airborne platform capability. The advantages of airships as remote sensing platforms include payload capacity, platform stability, low noise, long endurance and wide operating altitude range. A description is given of the aircraft available from the American Blimp Corporation.
{"title":"Airships: an ideal platform for human or remote sensing in the marine environment","authors":"E. J. Brandreth","doi":"10.1109/OCEANS.2000.882212","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.882212","url":null,"abstract":"The author describes what today's modern airship, \"blimp\", can offer to those wishing to have an airborne platform capability. The advantages of airships as remote sensing platforms include payload capacity, platform stability, low noise, long endurance and wide operating altitude range. A description is given of the aircraft available from the American Blimp Corporation.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"59 1","pages":"1883-1885 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77911354","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.2000.881782
E. Kuntsal
This paper presents efficiency calculation methods from data and discusses related areas of concern. Two major methods are used to calculate the electroacoustic efficiency of a transducer from data: direct and admittance. In the direct method, first the electrical input and acoustical output power are measured, and then the efficiency is calculated directly from these parameters. In the admittance method, the input and output power are inferred from in air and water admittance measurements of a transducer.
{"title":"Accuracy issues on the calculation of efficiency for piezoelectric underwater transducers","authors":"E. Kuntsal","doi":"10.1109/OCEANS.2000.881782","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881782","url":null,"abstract":"This paper presents efficiency calculation methods from data and discusses related areas of concern. Two major methods are used to calculate the electroacoustic efficiency of a transducer from data: direct and admittance. In the direct method, first the electrical input and acoustical output power are measured, and then the efficiency is calculated directly from these parameters. In the admittance method, the input and output power are inferred from in air and water admittance measurements of a transducer.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"53 1","pages":"1293-1297 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78075244","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.2000.881741
P. M. Oliveira, V. Barroso
The complexity of real-life transients, coupled with the incomplete (or absent) knowledge of their statistical structure or defining features has motivated the interest on the use of blind, data driven detection schemes. One such scheme, proposed by Jones and Sayeed (1995), uses time-frequency distributions to implement sub-optimal quadratic detectors which, under certain conditions, approach the performance of optimal quadratic detectors. However, their use of Fisher's discriminants to obtain class separation has some drawbacks, which we solve by using a simple perceptron to obtain the discriminant. Also, more often than not, we will have a multiclass situation, implying the use of different time-frequency distributions, each one of them tuned for a given class of transients. The different nature of these distributions (bias, type of cross-terms, time-frequency resolution, etc.) will hamper the performance of the algorithm, forcing the need for experimental validation of its heuristical aspects. The algorithm will be applied to real data, and its performance investigated.
{"title":"Data driven underwater transient detection based on time-frequency distributions","authors":"P. M. Oliveira, V. Barroso","doi":"10.1109/OCEANS.2000.881741","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881741","url":null,"abstract":"The complexity of real-life transients, coupled with the incomplete (or absent) knowledge of their statistical structure or defining features has motivated the interest on the use of blind, data driven detection schemes. One such scheme, proposed by Jones and Sayeed (1995), uses time-frequency distributions to implement sub-optimal quadratic detectors which, under certain conditions, approach the performance of optimal quadratic detectors. However, their use of Fisher's discriminants to obtain class separation has some drawbacks, which we solve by using a simple perceptron to obtain the discriminant. Also, more often than not, we will have a multiclass situation, implying the use of different time-frequency distributions, each one of them tuned for a given class of transients. The different nature of these distributions (bias, type of cross-terms, time-frequency resolution, etc.) will hamper the performance of the algorithm, forcing the need for experimental validation of its heuristical aspects. The algorithm will be applied to real data, and its performance investigated.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"65 1","pages":"1059-1063 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82093599","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.2000.882210
J. Hannon
The ability to collect, process, display, distribute and store oceanographic data at sea in real time has always been critical to meet the ever changing environmental requirements of the tactical, scientific and commercial offshore communities. With the development of the expendable bathythermooraph (XBT) by Sippican, Inc. back in 1962, profiles of ocean temperature could be collected at ship speeds up to 30 kts in virtually any weather. Data recording systems provided a hard copy trace on pressure sensitive paper, which required time consuming and expensive digitization before archiving. Over 5 million XBT profiles were analyzed using this technique. In recent years with the advent and adaptation of new solid state sensors for sound velocity, salinity, current velocity, optical properties and sediment characterization along with new microprocessor based acquisition systems, it is now possible to collect display and process a wide range of oceanographic parameters at sea.
{"title":"New developments in expendable oceanographic sensors and data acquisition systems","authors":"J. Hannon","doi":"10.1109/OCEANS.2000.882210","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.882210","url":null,"abstract":"The ability to collect, process, display, distribute and store oceanographic data at sea in real time has always been critical to meet the ever changing environmental requirements of the tactical, scientific and commercial offshore communities. With the development of the expendable bathythermooraph (XBT) by Sippican, Inc. back in 1962, profiles of ocean temperature could be collected at ship speeds up to 30 kts in virtually any weather. Data recording systems provided a hard copy trace on pressure sensitive paper, which required time consuming and expensive digitization before archiving. Over 5 million XBT profiles were analyzed using this technique. In recent years with the advent and adaptation of new solid state sensors for sound velocity, salinity, current velocity, optical properties and sediment characterization along with new microprocessor based acquisition systems, it is now possible to collect display and process a wide range of oceanographic parameters at sea.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"1993 1","pages":"1875-1877 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82395468","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.2000.881730
L. Antonelli, I. Kirsteins
The basic operation of a novel laser-based sensor is investigated. A low power laser beam emanating from a laser Doppler velocimeter is used to interrogate an air-water interface for underwater sound detection. The sensor measures the normal velocity of the vibrations of the pressure release air-water interface. The objective of this paper is to discuss the feasibility and fundamental limitations on using the laser-based acoustic field velocity measurements of hydrodynamic air-water interface to determine acoustic field direction of arrival. This paper identifies the various contributions to bearing uncertainty using the Cramer-Rao lower bounds to establish the limitations of determining the bearing of the in-water sound.
{"title":"Bearing estimation error analysis using laser acoustic sensor measurements on a hydrodynamic surface","authors":"L. Antonelli, I. Kirsteins","doi":"10.1109/OCEANS.2000.881730","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881730","url":null,"abstract":"The basic operation of a novel laser-based sensor is investigated. A low power laser beam emanating from a laser Doppler velocimeter is used to interrogate an air-water interface for underwater sound detection. The sensor measures the normal velocity of the vibrations of the pressure release air-water interface. The objective of this paper is to discuss the feasibility and fundamental limitations on using the laser-based acoustic field velocity measurements of hydrodynamic air-water interface to determine acoustic field direction of arrival. This paper identifies the various contributions to bearing uncertainty using the Cramer-Rao lower bounds to establish the limitations of determining the bearing of the in-water sound.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"62 1","pages":"999-1004 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86129807","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.2000.882246
C. Webers, U. Zimmer
Robust tracking of vehicles under uncertain, noisy, and discontinuous positioning is a significant part of autonomous navigation in unknown environments. The article suggests two methods for track control, where the initial parameters of the online control are physically explainable, the resulting track as well as the control parameters are asymptotically converging and glitches in the localization are handled robustly. Practical experiments with landbound vehicles show the reliability and limitations of the method in various environments in setups for following simple attractors. Due to the physical meaning of the control parameters the adaptation to changed kinematic or dynamics is significantly simplified.
{"title":"Robust tracking under uncertainties","authors":"C. Webers, U. Zimmer","doi":"10.1109/OCEANS.2000.882246","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.882246","url":null,"abstract":"Robust tracking of vehicles under uncertain, noisy, and discontinuous positioning is a significant part of autonomous navigation in unknown environments. The article suggests two methods for track control, where the initial parameters of the online control are physically explainable, the resulting track as well as the control parameters are asymptotically converging and glitches in the localization are handled robustly. Practical experiments with landbound vehicles show the reliability and limitations of the method in various environments in setups for following simple attractors. Due to the physical meaning of the control parameters the adaptation to changed kinematic or dynamics is significantly simplified.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"30 1","pages":"2107-2113 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86402344","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.2000.882254
X. Li, K. Holappa, K. Nelson
Injection molded plastic (Ultem) pressure vessels are used as modular underwater vehicle body sections on the morpheus autonomous underwater vehicle at Florida Atlantic University. The bulk properties of the material were used in the design and analysis due to the lack of effective property data of the Ultem injection module which are actually dependent on the molding process. A series of test specimens were prepared and tested to determine the tensile strength, bending strength, shear strength and Young's modulus achieved in the final modules. Implementation of the control surface actuators that penetrate the plastic pressure vessel requires an assessment of the desired failure mode of the system and an accurate structural model of the system components. A nonlinear finite element analysis of the actuator system including the plastic modules is developed as a quarter section in order to take advantage of the symmetry of the problem. Finally, failure modes are found using von Mises analysis.
{"title":"Failure analysis of an injection molded modular tail section on an autonomous underwater vehicle","authors":"X. Li, K. Holappa, K. Nelson","doi":"10.1109/OCEANS.2000.882254","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.882254","url":null,"abstract":"Injection molded plastic (Ultem) pressure vessels are used as modular underwater vehicle body sections on the morpheus autonomous underwater vehicle at Florida Atlantic University. The bulk properties of the material were used in the design and analysis due to the lack of effective property data of the Ultem injection module which are actually dependent on the molding process. A series of test specimens were prepared and tested to determine the tensile strength, bending strength, shear strength and Young's modulus achieved in the final modules. Implementation of the control surface actuators that penetrate the plastic pressure vessel requires an assessment of the desired failure mode of the system and an accurate structural model of the system components. A nonlinear finite element analysis of the actuator system including the plastic modules is developed as a quarter section in order to take advantage of the symmetry of the problem. Finally, failure modes are found using von Mises analysis.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"25 1","pages":"2161-2168 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86523827","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.2000.881249
K. Tamura, T. Aoki, T. Nakamura, S. Tsukioka, T. Murashima, H. Ochi, H. Nakajoh, T. Ida, T. Hyakudome
JAMSTEC started on the development project of AUV in 1998 fiscal year, and the first test machine AUV-EX1 which renamed Urashima has been developed in March 2000. Urashima has many excellent features. The cruising range is relatively long and working depth is very deep. It has a new inertia navigation system with ring laser gyros. The fuel cell system will be selected for its power device. From this June, the first test in the sea of Urashima and the fuel cell test on ground have started. This paper introduces the feature of Urashima, and shows an outline of these tests.
{"title":"The development of the AUV-Urashima","authors":"K. Tamura, T. Aoki, T. Nakamura, S. Tsukioka, T. Murashima, H. Ochi, H. Nakajoh, T. Ida, T. Hyakudome","doi":"10.1109/OCEANS.2000.881249","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881249","url":null,"abstract":"JAMSTEC started on the development project of AUV in 1998 fiscal year, and the first test machine AUV-EX1 which renamed Urashima has been developed in March 2000. Urashima has many excellent features. The cruising range is relatively long and working depth is very deep. It has a new inertia navigation system with ring laser gyros. The fuel cell system will be selected for its power device. From this June, the first test in the sea of Urashima and the fuel cell test on ground have started. This paper introduces the feature of Urashima, and shows an outline of these tests.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"62 1","pages":"139-146 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83179881","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.2000.881316
D. Codiga, Joseph Rice, P. S. Bogden
A novel system to use networked acoustic modems for real-time wireless delivery of oceanographic measurements from a distributed array of subsurface instruments in coastal waters is presented. The network consists of sensor nodes, repeater nodes, gateway nodes, and a server. Gateway nodes are buoys equipped with acoustic modems interfaced to Internet-accessible cellular modems for two-way communication between server and subsurface network. Network data flow is remotely re-configurable with multiple paths to the server from each sensor so loss or failure of an individual node can be accommodated. Oceanographic instruments are housed in bottom-mounted frames to limit biofouling and minimize fishing and shipping interference. A trawl-resistant frame enables azimuthally omnidirectional acoustic signaling as required for the network. Gateways serve multiple sensors distributed across wide areas, minimizing the number of instruments with surface exposure. A low-bandwidth data format for acoustic Doppler current profilers is devised to reduce network throughput and power consumption. Gateway equipment is engineered for a Coast Guard buoy. Tests in winter and spring indicate wind limits acoustic communications range by roughening the sea surface. A preliminary network deployment demonstrates gateway control, data delivery across multiple repeaters, and route reconfiguration.
{"title":"Real-time delivery of subsurface coastal circulation measurements from distributed instruments using networked acoustic modems","authors":"D. Codiga, Joseph Rice, P. S. Bogden","doi":"10.1109/OCEANS.2000.881316","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881316","url":null,"abstract":"A novel system to use networked acoustic modems for real-time wireless delivery of oceanographic measurements from a distributed array of subsurface instruments in coastal waters is presented. The network consists of sensor nodes, repeater nodes, gateway nodes, and a server. Gateway nodes are buoys equipped with acoustic modems interfaced to Internet-accessible cellular modems for two-way communication between server and subsurface network. Network data flow is remotely re-configurable with multiple paths to the server from each sensor so loss or failure of an individual node can be accommodated. Oceanographic instruments are housed in bottom-mounted frames to limit biofouling and minimize fishing and shipping interference. A trawl-resistant frame enables azimuthally omnidirectional acoustic signaling as required for the network. Gateways serve multiple sensors distributed across wide areas, minimizing the number of instruments with surface exposure. A low-bandwidth data format for acoustic Doppler current profilers is devised to reduce network throughput and power consumption. Gateway equipment is engineered for a Coast Guard buoy. Tests in winter and spring indicate wind limits acoustic communications range by roughening the sea surface. A preliminary network deployment demonstrates gateway control, data delivery across multiple repeaters, and route reconfiguration.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"16 1","pages":"575-582 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81054854","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.2000.881277
John-Morten Godhavn
Accurate heave measurements are important in many applications to compensate for vessel wave motion, e.g. in hydrographic seabed mapping, dredging, and offshore crane heave compensation. The accuracy is often specified to be better than the larger of 5 cm and 5% relative. And with more and more accurate echo sounders and attitude sensors, there will be a demand for even more accurate and robust heave sensors in the future. This paper discusses several methods, both on-line methods for real-time heave computation and off-line methods for post processing. It will also treat two different technologies. Heave can be computed from GPS RTK height measurements and from vertical accelerations measured by linear accelerometers. Integrated solutions that combine these two technologies are also discussed.
{"title":"High quality heave measurements based on GPS RTK and accelerometer technology","authors":"John-Morten Godhavn","doi":"10.1109/OCEANS.2000.881277","DOIUrl":"https://doi.org/10.1109/OCEANS.2000.881277","url":null,"abstract":"Accurate heave measurements are important in many applications to compensate for vessel wave motion, e.g. in hydrographic seabed mapping, dredging, and offshore crane heave compensation. The accuracy is often specified to be better than the larger of 5 cm and 5% relative. And with more and more accurate echo sounders and attitude sensors, there will be a demand for even more accurate and robust heave sensors in the future. This paper discusses several methods, both on-line methods for real-time heave computation and off-line methods for post processing. It will also treat two different technologies. Heave can be computed from GPS RTK height measurements and from vertical accelerations measured by linear accelerometers. Integrated solutions that combine these two technologies are also discussed.","PeriodicalId":68534,"journal":{"name":"中国会展","volume":"1 1","pages":"309-314 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89368497","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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