OCEANS 2006 - Asia Pacific最新文献

{"title":"Symmetric Wing Sections for the Switchback Motion of the Very Large Mobile Offshore Structure","authors":"K. Takagi, Y. Yoshitake","doi":"10.1109/OCEANSAP.2006.4393839","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393839","url":null,"abstract":"We propose a new concept of VLMOS, which is composed of slender beams, demi-hulls and struts. The struts are wing-shaped, so that the wing induces a lateral force to counter the lateral wind drag force. The shapes of strut wings are symmetrical in the direction of the cord and their both ends have sharp edge. The main topic of this paper is to analyze the characteristic of the strut wings. We have carried out the model experiment and the calculation to estimate the performance of the strut wings.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124693015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Software Acoustic Modems for Short Range Mote-based Underwater Sensor Networks","authors":"R. Jurdak, C. Lopes, P. Baldi","doi":"10.1109/OCEANSAP.2006.4393864","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393864","url":null,"abstract":"Most recent work in underwater network development has relied on using expensive commercial acoustic modems or on building custom transceivers for each application to establish acoustic communication links among the sensors. Using commercial modems or designing custom hardware may require prohibitive monetary or time investment for many applications. Our work proposes the design of software acoustic modems that can utilize built-in microphones and speakers on the relatively cheap Tmote Invent platforms. The built-in Tmote hardware and the software modem enable acoustic communication in a short range shallow water network. In this paper, we present the initial design and architecture of our acoustic communication system which targets environmental monitoring applications. Our experiments with generic acoustic hardware to profile this underwater communication channel reveal that the channel favors frequencies below 3 Khz, a result which guides the design choices for our FSK software modem. We perform experiments with our software modem/generic hardware system to explore the system's data transfer capability. The data communications experiments confirm the system's capability of transferring information in the order of tens of bits per second for a communications range of up to 10 meters.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127339730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of Automated Dual Elevator System Enabling Deeper Drilling","authors":"T. Inoue","doi":"10.1109/OCEANSAP.2006.4393836","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393836","url":null,"abstract":"The scientific Deep-Sea Drilling Vessel \"Chikyu\" was designed to have the capability to drill down to a maximum drill string length of 10,000 m and technical equipment developments were needed in order to achieve this drilling depth. During drilling operation a hoop stress is generated by conventional handling equipment slips. The hoop stress can become critical with the increased drill string length if the force is sufficient and can actually damage or in the extreme case crush the pipe. This phenomenon is called slip-crushing. In order to avoid this potential problem and to reach the drilling depth (the length of the drill string) of 10,000 m, the automated Dual Elevator System (patent pending), which is an integrated pipe handling system using two elevators, has been developed for \"Chikyu\". This paper describes the critical problem such as the slip-crushing due to the hoop stress in ultra deep drilling which will be the intended operations for \"Chikyu\". It is a problem of this type which determines maximum drilling depth which in turn limits the access to deep formations where core samples recovered. Also, this describes the outline of functions and automation system of the Dual Elevator System.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129143964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vector Hydrophone Array Development and its Associated DOA Estimation Algorithms","authors":"Nan Zou, Chia Chin Swee, B. Chew","doi":"10.1109/OCEANSAP.2006.4393852","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393852","url":null,"abstract":"Unlike scalar pressure sensors, acoustic vector sensors measure the amplitude and phase of acoustic particle motion in a dedicated direction. An underwater acoustic particle velocity sensor provides significant operational advantages over traditional hydrophones by providing the amplitude and the three dimensional directions of the acoustic signals it senses It can improve performance with a smaller array aperture as compared to the classic scalar hydrophone array. The vector sensor array can estimate the azimuth and elevation angles of the target without left/right ambiguity that occurs in towed array scenario. Within this paper we present an approach to develop a three-axis underwater acoustic vector sensor array and its associated DOA (direction of arrival) estimation algorithm. The physical model of acoustic vector sensor array is introduced and the model is further extended for the implementation rationale with scalar pressure sensing hydrophones. The array performance, especially the array gain of the vector hydrophone array under 3D isotropic ambient noise environment is analyzed as a guideline to develop the vector hydrophone array. A seven-element vector hydrophone array is designed following the theoretical model developed. The characteristics of the vector array proves to be consistent with the theoretical analysis We further introduce the high resolution bearing estimation algorithm of the vector hydrophone array.The vector form M VDR beamforming algorithm is introduced and the performance of the vector hydrophone array and the associated beamforming algorithm are evaluated by an on site trial. The results show that the vector hydrophone array performs well in the estimation of the DOA of both azimuth and elevation of the target.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121487955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"GIS for Manmade Object Contacts from Sidescan Sonar Images","authors":"Ning Ma, W. Chan, D. Raju, S. Natesan, Keng Pong Yeo","doi":"10.1109/OCEANSAP.2006.4393960","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393960","url":null,"abstract":"Abstract -In this paper, we describe a in-house developed software system for manmade object detection and the geo-localization based on sidescan sonar image. The system contains the process of detecting objects in a sidescan sonar image, outlining the detected objects in a mosaic image which is formed by mosaicing several swathes of sonar images, and saving the detected objects in a geo-information data base. The automatic object detection algorithm is based on the reflection strength (highlights), shadows and their properties. Information on detected objects such as the estimated size, shape and their geo-locations are retrieved by the analysis. The localized objects and ancillary information are subsequently loaded into a Geographical Information System (GIS). This enhances the value of the information as they can then be viewed and queried in conjunction with other useful information like bathymetry, currents and seabed sediment types in an interactive map-based display over the Internet.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114261271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Detection of Tsunami Induced Changes from High Resolution Satellite Imagery","authors":"Emre Sumer, Fatih V. Celebi","doi":"10.1109/OCEANSAP.2006.4393934","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393934","url":null,"abstract":"The 2004 Indian Ocean earthquake, also known as the Sumatra-Andaman earthquake, was an undersea earthquake that occurred at 00:58:53 UTC (07:58:53 local time) on December 26, 2004. The tsunami, generated by the earthquake killed approximately 275,000 people, injured lots more and forced many individuals to leave their homes. The earthquake originated in the Indian Ocean just north of Simeulue Island, off the western coast of northern Sumatra, Indonesia. The resulting tsunami devastated the shores of Indonesia, Sri Lanka, South India, Thailand and other countries with waves up to 30 m (100 ft). In this study, the detection of changes due to the tsunami after the earthquake is performed. The images of the suffered region are acquired by Quick Bird satellite of Digital Globe Company, taken before (on April 12, 2004) and after (on January 2, 2005) the disaster. The aim of this study is to find the location of the changed regions and to specify the intensity of the change by using various change detection algorithms, which are the image algebra (band differencing and band rationing), post-classification comparison, the binary mask applied to date-2 and write function memory insertion. The image algebra techniques are generally used in two forms, which are called band differencing and band rationing. Band differencing is probably the most widely applied change detection algorithm that involves subtracting one date of imagery from a second date that has been precisely registered to the first. The resulting image contains both negative and positive values, which indicate the change between the images. Intuitively, if there is no change, then the expected values from image differencing would be zero. Similar to image differencing, change detection can also be achieved through band rationing. The basic idea is to create ratios between two different images of the same area. The areas of no change in this procedure will result in value of 1, where changes greater and less than 1 indicates the differences between the images. In post classification comparison, each image is classified by using a supervised classification algorithm (e.g. Maximum Likelihood Classifier) and the classified images are compared pixel by pixel In the binary mask applied to date-2 method, the pre-event image is firstly classified and then a new image is generated by performing algebraic operations on an arbitrary common band of the pre-and post-event images. In addition to that, a threshold value is determined whether a change occurs or not. The regions under the threshold are removed and the remaining parts are specified as changed regions. In the last technique, write function memory insertion, the individual bands of the images are inserted into specific write function memory banks (red, green or blue) in a digital image processing system. During the implementation of these methods, Matlab programming language, which is quite efficient in image processing operations, is used. The r","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"135 3-4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123134847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Miniaturized Underwater Sensors for the Realization of Conformal Arrays","authors":"D. Rajapan, P. Rajeshwari, M. Sankar, K. Trinath, N. S. Prasad","doi":"10.1109/OCEANSAP.2006.4393846","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393846","url":null,"abstract":"The development of cymbal transducers in India and the primary results obtained are presented in this paper. Commercial software ATILA is used to model Cymbal transducers. Simulation as well as experimental results are presented. The fundamental flexural resonance frequency of the transducers in water is ~20 kHz, for the cymbal with 12.7 mm cap diameter. The simulation studies showed that the resonant frequency can be reduced to ~8 kHz for a 19 mm cap Cymbal where as it reduces to ~3 kHz when the diameter increases to 30 mm. Pure brass caps showed a better performance compared to naval brass. Large d33 values of the order >15000 Pico Coulomb/N has been experimentally measured for the standard cymbals with PZT-5A where as the values are ~7000-9000 Pico Coulomb/N using PZT-4. The standard cymbals with pure brass showed the resonance frequency around 19kHz in water and a TVR value of ~120 dBre 1 muPa/V @ 1 m has been measured at resonance frequency. A receiving sensitivity (RS) of -205 dBre 1 V/muPa has been obtained on single element cymbals. In addition to single elements, a 3times3 array of cymbals have been fabricated and tested using two different water tight encapsulation. A 3times3 array with 3 M epoxy encapsulation gave a TVR value of ~135 dBre 1 muPa/V@ 1 m around 22 kHz for the standard cymbals of 12.7 mm diameter. A nearly flat frequency response is obtained for the array. An operating region of 15-90 kHz has been achieved. The Cymbals with 19 mm diameter using brass caps gave very high d33 values even >30000 Pico Coulomb/N. It resonated around 7 kHz in water while in-air resonance is 9 kHz. Probably this is the highest d33 value reported for a cymbal transducer as on to date. Earlier reports by Newnham et. al did not exceed a value of 15000 for standard cymbals.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132563647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Segmentation and Classification of Coral for Oceanographic Surveys: A Semi-Supervised Machine Learning Approach","authors":"M. Johnson-Roberson, Suresh Kumar, S. Willams","doi":"10.1109/OCEANSAP.2006.4393835","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393835","url":null,"abstract":"This work presents a technique for the autonomous segmentation and classification of coral through the combination of visual and acoustic data. Autonomous Underwater Vehicles (AUVs) facilitate the live capture of multi-modal sensor information about coral reefs. Environmental monitoring of these reefs can be aided though the autonomous extraction and identification of certain coral species of interest. The technique presented employs a two phase procedure of segmentation and classification to gather statistics about coral density during autonomous missions with an AUV.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130960265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A neural network approach for remote detection of marine eddies","authors":"M. Castellani","doi":"10.1109/OCEANSAP.2006.4393861","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393861","url":null,"abstract":"This paper presents a machine learning approach for detection of Mediterranean water eddies from sea surface temperature maps of the Atlantic ocean. Two methods based on texture analysis of the satellite imagery are evaluated. Given a map point, the first method extracts information on the surrounding thermal gradient and arranges it as a numerical vector of gradient angles. The second method uses laws' algorithm to create a vector of numerical measures of structural features. In both the cases, a neural network is trained to recognise those numerical patterns that reveal the presence of eddy structures. Both the algorithms achieve high recognition accuracy and fast and robust learning results. Particularly important are the very low rates of false detections obtained, since eddies occupy only a small portion of the ocean area. Compared to laws' method, the gradient-based algorithm gives comparable recognition accuracies with a lower design effort and at reduced computational costs. The simple and modular structure of the gradient-based method also compares favorably to the complexity other algorithms for identification of marine phenomena published in the literature. Given the competitive accuracy results obtained, the gradient-based approach may be preferable to the currently employed techniques since it is simpler and more easily reconfigurable.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126895898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Region-based and incidence angle dependent segmentation of seabed sonar images using a level set approach combined to local texture statistics","authors":"K. Imen, R. Fabler, J. Boucher, J. Augustin","doi":"10.1109/OCEANSAP.2006.4393854","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393854","url":null,"abstract":"We propose a region-based segmentation of textured sonar images within a level set framework. We state image segmentation as the minimization of an energy involving region regularity constraints and a texture similarity measure adapted to sonar images (introduced in our previous work [Karoui, I., et al., 2005]). In this framework, sonar textures are characterized by statistics of their responses to a set of filters, and the similarity between texture samples is measured according to a weighted sum of the Kullback-Leibler divergence between the compared texture statistics. The texture similarity measure weights setting is twofold: first we weight each filter, according to its discrimination power, the computation of these weights are issued from the margin maximization criterion. Second, we add an additional weighting, evaluated as an angular distance between the incidence angles of the compared texture samples, to cope with the problem related to the sonar image acquisition process that lead to a variability of the backscattered (BS) value and the texture aspect with the incidence angle range. We have tested the method, using different filter response first and second order distributions, on several sonar images. The results prove the relevance of the proposed method.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126638873","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}