Pub Date : 2006-05-16DOI: 10.1109/OCEANSAP.2006.4393832
M. Molins, M. Stojanovic
Long propagation delays and low bit rates of underwater acoustic networks make these systems fundamentally different from the packet radio networks. As a consequence, many of the network protocols designed for radio channels are either not applicable, or have extremely low efficiency over underwater acoustic channels. These facts necessitate a dedicated design of protocols for an underwater acoustic network. A medium access control (MAC) protocol suitable for an underwater acoustic network is proposed and analyzed. The protocol is based on a channel access discipline called floor acquisition multiple access (FAMA) which combines both carrier sensing (CS) and a dialogue between the source and receiver prior to data transmission. During the initial dialogue, control packets are exchanged between the source node and the intended destination node to avoid multiple transmissions at the same time. Special attention is paid to the networks that are not fully connected, in which nodes can be hidden from each other. The new protocol uses time slotting and is thus called slotted FAMA. Time slotting eliminates the need for excessively long control packets, thus providing savings in energy. Protocol performance in throughput and delay is assessed through simulation of a mobile ad hoc underwater network, showing the existence of optimal power level to be used for a given user density.
{"title":"Slotted FAMA: a MAC protocol for underwater acoustic networks","authors":"M. Molins, M. Stojanovic","doi":"10.1109/OCEANSAP.2006.4393832","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393832","url":null,"abstract":"Long propagation delays and low bit rates of underwater acoustic networks make these systems fundamentally different from the packet radio networks. As a consequence, many of the network protocols designed for radio channels are either not applicable, or have extremely low efficiency over underwater acoustic channels. These facts necessitate a dedicated design of protocols for an underwater acoustic network. A medium access control (MAC) protocol suitable for an underwater acoustic network is proposed and analyzed. The protocol is based on a channel access discipline called floor acquisition multiple access (FAMA) which combines both carrier sensing (CS) and a dialogue between the source and receiver prior to data transmission. During the initial dialogue, control packets are exchanged between the source node and the intended destination node to avoid multiple transmissions at the same time. Special attention is paid to the networks that are not fully connected, in which nodes can be hidden from each other. The new protocol uses time slotting and is thus called slotted FAMA. Time slotting eliminates the need for excessively long control packets, thus providing savings in energy. Protocol performance in throughput and delay is assessed through simulation of a mobile ad hoc underwater network, showing the existence of optimal power level to be used for a given user density.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114557818","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 : 2006-05-16DOI: 10.1109/OCEANSAP.2006.4393938
C. Tan, A. Sluzek, G. Seet G. L, T. Jiang
This paper introduces the work that has been done to improve the underwater visibility from underwater robotic vehicle (URV) for sub-sea inspection and repair missions. It is undertaken as part of a research program to develop an underwater imaging system in turbid water condition. Images associated with underwater imaging systems are frequently degraded due to absorption and scattering effects from its underwater environment. The absorption effect reduces the signal strength, and the latter effect reduces both signal strength and image resolution. In order to improve the underwater visibility in turbid conditions, general design considerations of the imaging system are planned in two stages, namely: hardware upgrading and system optimization. We demonstrate this concept by improving the underwater visibility with an advanced technique -range gated imaging system (hardware upgrading), and the optimization stage in terms of tail-gating and image processing techniques. Tail-gating is realized by a delay in camera gating towards the tail of reflected image temporal profile (RITP). It is followed by contrast limited adaptive histogram equalization (CLAHE) to further enhance the range-gated images. A quantitative image quality measure, modified fidelity index (MF), is used to evaluate the enhanced imaging techniques. The measure is based on 2 dimensional grayscale images of USAF (United State Air Force) targets. These targets have been used extensively in underwater imaging system development. It has resolution bars in various frequencies and arrangement, which enable spatial frequencies and signal strength analysis. In the first stage, the MF index shows at least 40% improvement from non-gated to gated images in increased turbidity. By comparing images between Front-gated to the Tail-gated RITP quantitatively, the latter is improved by about 4% -22% (based on MF index) in various turbidity levels. Finally, the CLAHE technique further improves the gated images in terms of contrast gain.
{"title":"Range Gated Imaging System for Underwater Robotic Vehicle","authors":"C. Tan, A. Sluzek, G. Seet G. L, T. Jiang","doi":"10.1109/OCEANSAP.2006.4393938","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393938","url":null,"abstract":"This paper introduces the work that has been done to improve the underwater visibility from underwater robotic vehicle (URV) for sub-sea inspection and repair missions. It is undertaken as part of a research program to develop an underwater imaging system in turbid water condition. Images associated with underwater imaging systems are frequently degraded due to absorption and scattering effects from its underwater environment. The absorption effect reduces the signal strength, and the latter effect reduces both signal strength and image resolution. In order to improve the underwater visibility in turbid conditions, general design considerations of the imaging system are planned in two stages, namely: hardware upgrading and system optimization. We demonstrate this concept by improving the underwater visibility with an advanced technique -range gated imaging system (hardware upgrading), and the optimization stage in terms of tail-gating and image processing techniques. Tail-gating is realized by a delay in camera gating towards the tail of reflected image temporal profile (RITP). It is followed by contrast limited adaptive histogram equalization (CLAHE) to further enhance the range-gated images. A quantitative image quality measure, modified fidelity index (MF), is used to evaluate the enhanced imaging techniques. The measure is based on 2 dimensional grayscale images of USAF (United State Air Force) targets. These targets have been used extensively in underwater imaging system development. It has resolution bars in various frequencies and arrangement, which enable spatial frequencies and signal strength analysis. In the first stage, the MF index shows at least 40% improvement from non-gated to gated images in increased turbidity. By comparing images between Front-gated to the Tail-gated RITP quantitatively, the latter is improved by about 4% -22% (based on MF index) in various turbidity levels. Finally, the CLAHE technique further improves the gated images in terms of contrast gain.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"225 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123981541","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 : 2006-05-16DOI: 10.1109/OCEANSAP.2006.4393918
P. Seekings, T. Koay, M. Chitre, V. Payallil, P. Deshpande, Jing Jin, L. Lim
Relaxor single crystals such as PZN-PT and PMN-PT exhibit superior electromechanical properties and are touted as the next-generation materials for future high performance piezo devices. This work describes a new hydrophone made of high-sensitivity PZN-PT single crystal d31 sensing elements. Three such elements are mounted in custom-made housing. A compartment is provided to house the three pre-amplifiers, one for each element. In the current prototype each element has its own input. This allows the directionality of each element to be measured and the possibility of locating the source direction from the combined signals of the three elements. A compact low noise high impedance voltage follower pre-amplifier has been designed which provides 26 dB of gain. The overall sensitivity was measured to be -169 dB re 1 V/muPa. Directionality has been measured to be approximately omni-directional within plusmn1 dB, up to a frequency of 7 kHz.
弛豫单晶，如PZN-PT和PMN-PT具有优异的机电性能，被吹捧为未来高性能压电器件的下一代材料。本文介绍了一种由高灵敏度PZN-PT单晶d31传感元件制成的新型水听器。三个这样的元件安装在定制的外壳中。提供一个隔间来容纳三个前置放大器，每个元件一个。在当前的原型中，每个元素都有自己的输入。这样就可以测量每个元件的方向性，并且可以从三个元件的组合信号中定位源方向。设计了一种增益为26db的紧凑型低噪声高阻抗电压从动器前置放大器。测量的总灵敏度为-169 dB / 1v /muPa。方向性已被测量为大约全向，在±n1 dB范围内，高达7 kHz的频率。
{"title":"Perfomance Evaluation Of A Singal Crystal Hydrophone","authors":"P. Seekings, T. Koay, M. Chitre, V. Payallil, P. Deshpande, Jing Jin, L. Lim","doi":"10.1109/OCEANSAP.2006.4393918","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393918","url":null,"abstract":"Relaxor single crystals such as PZN-PT and PMN-PT exhibit superior electromechanical properties and are touted as the next-generation materials for future high performance piezo devices. This work describes a new hydrophone made of high-sensitivity PZN-PT single crystal d31 sensing elements. Three such elements are mounted in custom-made housing. A compartment is provided to house the three pre-amplifiers, one for each element. In the current prototype each element has its own input. This allows the directionality of each element to be measured and the possibility of locating the source direction from the combined signals of the three elements. A compact low noise high impedance voltage follower pre-amplifier has been designed which provides 26 dB of gain. The overall sensitivity was measured to be -169 dB re 1 V/muPa. Directionality has been measured to be approximately omni-directional within plusmn1 dB, up to a frequency of 7 kHz.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132837821","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 : 2006-05-16DOI: 10.1109/OCEANSAP.2006.4393965
Rong Yang, G. W. Ng, Ning Ma, C. S. Chia
In this paper, we introduce a target Bearing and Heading Tracking algorithm (BHT) using bearing-only measurement from a stationary sonar sensor. Since the target location is impossible to be obtained from a single stationary bearing-only sensor, the optimal output of this sensor is the quality bearing tracks. The conventional Bearing-Only Tracker (BOT) using an Extended Kalman Filter (EKF) does not perform well. This is because EKF is sensitive to the initial state, and the initial state is difficult to estimate in bearing-only detection. In BHT algorithm, a target heading is computed from a sequence of measured bearings, and this heading form the measurement vector together with measured bearing The state vector is the same as the extended Kalman Filter to track target dummy location and velocity, and the final bearing and heading values are computed from tracked location and velocity. The simulation results show that BHT algorithm is with good performance in terms of track accuracy, and with less false tracks. Besides the quality bearing tracks, the BHT also provides heading information which can be further utilized, as a very useful feature, on target localization in multiple sensors environment.
{"title":"A Bearing and Heading Tracker from a Stationary Sonar Sensor","authors":"Rong Yang, G. W. Ng, Ning Ma, C. S. Chia","doi":"10.1109/OCEANSAP.2006.4393965","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393965","url":null,"abstract":"In this paper, we introduce a target Bearing and Heading Tracking algorithm (BHT) using bearing-only measurement from a stationary sonar sensor. Since the target location is impossible to be obtained from a single stationary bearing-only sensor, the optimal output of this sensor is the quality bearing tracks. The conventional Bearing-Only Tracker (BOT) using an Extended Kalman Filter (EKF) does not perform well. This is because EKF is sensitive to the initial state, and the initial state is difficult to estimate in bearing-only detection. In BHT algorithm, a target heading is computed from a sequence of measured bearings, and this heading form the measurement vector together with measured bearing The state vector is the same as the extended Kalman Filter to track target dummy location and velocity, and the final bearing and heading values are computed from tracked location and velocity. The simulation results show that BHT algorithm is with good performance in terms of track accuracy, and with less false tracks. Besides the quality bearing tracks, the BHT also provides heading information which can be further utilized, as a very useful feature, on target localization in multiple sensors environment.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116562684","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 : 2006-05-16DOI: 10.1109/OCEANSAP.2006.4393943
K. Nallaperumal, J. Varghese, S. Saudia, K. Arulmozhi, K. Velu, S. Annam
An effective median filter for salt & pepper impulse noise removal is presented. This computationally efficient filtering technique is implemented by a two pass algorithm; In the first pass, identification of corrupted pixels that are to be filtered are perfectly detected into a flag image using a variable sized detection window approach; In the second pass, using the detected flag image, the pixels to be modified are identified and corrected by a more suitable median. Experimental results show that the proposed algorithm performs far more superior than many of the median filtering techniques reported in terms of retaining the fidelity of the image highly corrupted by impulse noises even to the tune of ninety percent impulse noise. The proposed algorithm is free from patchy effects, does not extend black or white blocks in the image as has been found in many other adaptive median based techniques and is very effective in cases when images are corrupted with large percentage of impulse noises. This algorithm works very well for images with lower percentage of impulse noises also.
{"title":"Salt & Pepper Impulse Noise Removal using Adaptive Switching Median Filter","authors":"K. Nallaperumal, J. Varghese, S. Saudia, K. Arulmozhi, K. Velu, S. Annam","doi":"10.1109/OCEANSAP.2006.4393943","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393943","url":null,"abstract":"An effective median filter for salt & pepper impulse noise removal is presented. This computationally efficient filtering technique is implemented by a two pass algorithm; In the first pass, identification of corrupted pixels that are to be filtered are perfectly detected into a flag image using a variable sized detection window approach; In the second pass, using the detected flag image, the pixels to be modified are identified and corrected by a more suitable median. Experimental results show that the proposed algorithm performs far more superior than many of the median filtering techniques reported in terms of retaining the fidelity of the image highly corrupted by impulse noises even to the tune of ninety percent impulse noise. The proposed algorithm is free from patchy effects, does not extend black or white blocks in the image as has been found in many other adaptive median based techniques and is very effective in cases when images are corrupted with large percentage of impulse noises. This algorithm works very well for images with lower percentage of impulse noises also.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131556950","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 : 2006-05-16DOI: 10.1109/OCEANSAP.2006.4393944
T. Ura, K. Nagahashi, A. Asada, K. Okamura, K. Tamaki, T. Sakamaki, K. Iizasa
In August 2005, we succeeded in operating AUV "r2D4", which was constructed in July 2003 as one of fruits of R-Two project, into Myojin-sho underwater Caldera in full autonomous mode. The caldera is located about 800 km in the south of Tokyo, and 8 km in diameter. There is an active underwater volcano Myojin-sho at the Northeastern part of outer rim of caldera, which erupted repeatedly in 1952. The Kuroshio current is usually running over the Caldera, so that current speed around it is sometimes more than 3 knots. It can be said that the diving of human occupied vehicle and remotely operated vehicle into Myojin-sho Caldera is very dangerous due to such hostile environment. The interferometry SONAR captured a clear image of the central cone in the middle of crater, and the in-situ chemical analyzer "GAMOS" detected high concentration of manganese ion which indicates hydro-thermal activity in the crater.
{"title":"Dive into Myojin-sho Underwater Caldera","authors":"T. Ura, K. Nagahashi, A. Asada, K. Okamura, K. Tamaki, T. Sakamaki, K. Iizasa","doi":"10.1109/OCEANSAP.2006.4393944","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393944","url":null,"abstract":"In August 2005, we succeeded in operating AUV \"r2D4\", which was constructed in July 2003 as one of fruits of R-Two project, into Myojin-sho underwater Caldera in full autonomous mode. The caldera is located about 800 km in the south of Tokyo, and 8 km in diameter. There is an active underwater volcano Myojin-sho at the Northeastern part of outer rim of caldera, which erupted repeatedly in 1952. The Kuroshio current is usually running over the Caldera, so that current speed around it is sometimes more than 3 knots. It can be said that the diving of human occupied vehicle and remotely operated vehicle into Myojin-sho Caldera is very dangerous due to such hostile environment. The interferometry SONAR captured a clear image of the central cone in the middle of crater, and the in-situ chemical analyzer \"GAMOS\" detected high concentration of manganese ion which indicates hydro-thermal activity in the crater.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126494465","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 : 2006-05-16DOI: 10.1109/OCEANSAP.2006.4393905
N. Chotiros
Over the past 50 years, a large number of bottom scattering measurements have been made at a very significant accumulated cost, particularly in the 10 kHz to 1 MHz range. While each measurement is valuable individually, the total collection is more valuable as a whole. The earliest measurements were made in the 1950s using simple sound sources and receivers, such as explosives and omni-directional hydrophones. In the 1960s, a large set of measurements were made with purpose-built sonar equipment by the Applied Research Laboratories of The University of Texas at Austin and others. The results indicated that backscattering strength increased with frequency, but later measurements did not uphold this trend. Another large set of measurements were made in the 1980s by the Applied Physics Laboratory of The University of Washington, which lead to further model development. Since then, many more measurements have been made by numerous institutions and individuals. No one measurement, or program of measurements, has been able to capture the diversity of the seabed. It appears that a database of all the published measurements is needed to fully comprehend the scope of the problem, and the physical processes involved. In parallel with the measurements, a number of models were developed. The earliest ones attempted to link backscattering strength to the sediment type or class, often represented by the mean grain size, in a purely empirical fashion. The earlier data sets appeared to support this approach but the trends are not supported by the database as a whole. Later models were based on physical representations. The seafloor is often modeled as a fluid with volume and roughness scattering mechanisms incorporated. More sophisticated models represented the seafloor as an elastic solid, and more recently as a poro-elastic medium. One objective has been to invert the acoustic backscatter measurements for sediment properties, but the data, so far, shows limited correlation between mean grain size and backscattering strength. The extant database may be used to explore the underlying physics. With respect to the sediment grain size, the scattering regime may be divided into a number of regimes. For grain sizes much smaller than the acoustic wavelength in water, the direct scattering from grains is weak and increases with frequency. This regime is only observed in the laboratory because in the real seafloor, other scattering mechanisms, including seafloor roughness such as sand ripples, and inclusions such as biogenic gas bubbles, and other fauna and flora often dominate the scattering process. In the next regime, where the grain size is of the same order of magnitude as the acoustic wavelength, the backscattering strength is well bounded. In this regime, models and data often agree. Finally, in the regime where the effective grain size is much larger than the acoustic wavelength, there is considerable variability in the data. In this regime, the concept of grain
{"title":"Seafloor acoustic backscattering strength and properties from published data","authors":"N. Chotiros","doi":"10.1109/OCEANSAP.2006.4393905","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393905","url":null,"abstract":"Over the past 50 years, a large number of bottom scattering measurements have been made at a very significant accumulated cost, particularly in the 10 kHz to 1 MHz range. While each measurement is valuable individually, the total collection is more valuable as a whole. The earliest measurements were made in the 1950s using simple sound sources and receivers, such as explosives and omni-directional hydrophones. In the 1960s, a large set of measurements were made with purpose-built sonar equipment by the Applied Research Laboratories of The University of Texas at Austin and others. The results indicated that backscattering strength increased with frequency, but later measurements did not uphold this trend. Another large set of measurements were made in the 1980s by the Applied Physics Laboratory of The University of Washington, which lead to further model development. Since then, many more measurements have been made by numerous institutions and individuals. No one measurement, or program of measurements, has been able to capture the diversity of the seabed. It appears that a database of all the published measurements is needed to fully comprehend the scope of the problem, and the physical processes involved. In parallel with the measurements, a number of models were developed. The earliest ones attempted to link backscattering strength to the sediment type or class, often represented by the mean grain size, in a purely empirical fashion. The earlier data sets appeared to support this approach but the trends are not supported by the database as a whole. Later models were based on physical representations. The seafloor is often modeled as a fluid with volume and roughness scattering mechanisms incorporated. More sophisticated models represented the seafloor as an elastic solid, and more recently as a poro-elastic medium. One objective has been to invert the acoustic backscatter measurements for sediment properties, but the data, so far, shows limited correlation between mean grain size and backscattering strength. The extant database may be used to explore the underlying physics. With respect to the sediment grain size, the scattering regime may be divided into a number of regimes. For grain sizes much smaller than the acoustic wavelength in water, the direct scattering from grains is weak and increases with frequency. This regime is only observed in the laboratory because in the real seafloor, other scattering mechanisms, including seafloor roughness such as sand ripples, and inclusions such as biogenic gas bubbles, and other fauna and flora often dominate the scattering process. In the next regime, where the grain size is of the same order of magnitude as the acoustic wavelength, the backscattering strength is well bounded. In this regime, models and data often agree. Finally, in the regime where the effective grain size is much larger than the acoustic wavelength, there is considerable variability in the data. In this regime, the concept of grain","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127806237","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 : 2006-05-16DOI: 10.1109/OCEANSAP.2006.4393841
K. Wada, M. Saito, H. Yamaguchi
The deep sea drilling vessel "CHIKYU" was completed in July 2005. The mission, which will be carried out with "CHIKYU ", is to gather geologic core samples under the seabed at the sea of deep water depth. The core samples and the drilled holes from which the core samples will be gathered will be used for the scientific studies to make clear the global environmental change, earthquake outbreak mechanism and biosphere under the sea-bed. The studies for these areas have been carried out under a scientific plan of Integrated Ocean Drilling Program (IODP). It is necessary to gather core samples from a deeper formation so that we can make these studies succeed Riser system and mud circulation system have been adopted to "CHIKYU " in order to gather core samples from a deep formation under the seabed. This is one of the drilling technologies used in the oil industry to enable drilling deeper. The mud circulation system is a system to circulate mud between drilling vessel and drilled hole. Risers are used as a return line of mud from the drilled hole. Mud is liquid of high specific gravity and high viscosity, and takes a lot of important roles, such as keeping the pressure balance between in and out of a hole, carrying the cuttings from a well out, protecting the wall of a hole, and so on. This means that mud circulation is be able to stabilize a well and as a result enables great depth drilling. On the other hand, mud circulation generates drilling waste such as waste mud and cuttings on board. In the oil industry, the drilling waste is usually abandoned into the sea. However, in late years the interest for an environmental problem has risen, and a standard of underwater abandonment of a drilling waste tends to become severe. In response to this situation, we decided to treat waste mud and cuttings adequately on "CHIKYU" as our policy from the viewpoint of environmentally friendship. "CHIKYU" is the first drilling vessel that has facilities to treat drilling waste called Waste Mud Treatment system. The drilling waste is classified to three kinds, waste mud, drill drain and cuttings. The mud used on "CHIKYU" is water base mud with a few exceptions. The principal ingredients are barite and bentnite basically. The drill drain is the thin muddy water that is occurred by washing of equipments for mud circulation. The cuttings is transferred to "CHIKYU" through the riser with mud, and they are separated from mud using shale shakers. The Waste Mud Treatment System consists of three sub-systems in correspondence with them. The waste mud is treated as follows. Firstly, solids in mud are cohered by chemicals. And the cohesion thing is squeezed by a screw press. The squeezed liquid from the cohesion thing is treated with drill drain together. The drill drain is thickened being heated, and thickened drill drain is treated with waste mud together. The solid squeezed from waste mud and the cuttings are stabilized with cement. In this way, the Waste Mud Treatment Syst
{"title":"Development of the Waste Mud Treatment System for Drilling Vessel \"CHIKYU\"","authors":"K. Wada, M. Saito, H. Yamaguchi","doi":"10.1109/OCEANSAP.2006.4393841","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393841","url":null,"abstract":"The deep sea drilling vessel \"CHIKYU\" was completed in July 2005. The mission, which will be carried out with \"CHIKYU \", is to gather geologic core samples under the seabed at the sea of deep water depth. The core samples and the drilled holes from which the core samples will be gathered will be used for the scientific studies to make clear the global environmental change, earthquake outbreak mechanism and biosphere under the sea-bed. The studies for these areas have been carried out under a scientific plan of Integrated Ocean Drilling Program (IODP). It is necessary to gather core samples from a deeper formation so that we can make these studies succeed Riser system and mud circulation system have been adopted to \"CHIKYU \" in order to gather core samples from a deep formation under the seabed. This is one of the drilling technologies used in the oil industry to enable drilling deeper. The mud circulation system is a system to circulate mud between drilling vessel and drilled hole. Risers are used as a return line of mud from the drilled hole. Mud is liquid of high specific gravity and high viscosity, and takes a lot of important roles, such as keeping the pressure balance between in and out of a hole, carrying the cuttings from a well out, protecting the wall of a hole, and so on. This means that mud circulation is be able to stabilize a well and as a result enables great depth drilling. On the other hand, mud circulation generates drilling waste such as waste mud and cuttings on board. In the oil industry, the drilling waste is usually abandoned into the sea. However, in late years the interest for an environmental problem has risen, and a standard of underwater abandonment of a drilling waste tends to become severe. In response to this situation, we decided to treat waste mud and cuttings adequately on \"CHIKYU\" as our policy from the viewpoint of environmentally friendship. \"CHIKYU\" is the first drilling vessel that has facilities to treat drilling waste called Waste Mud Treatment system. The drilling waste is classified to three kinds, waste mud, drill drain and cuttings. The mud used on \"CHIKYU\" is water base mud with a few exceptions. The principal ingredients are barite and bentnite basically. The drill drain is the thin muddy water that is occurred by washing of equipments for mud circulation. The cuttings is transferred to \"CHIKYU\" through the riser with mud, and they are separated from mud using shale shakers. The Waste Mud Treatment System consists of three sub-systems in correspondence with them. The waste mud is treated as follows. Firstly, solids in mud are cohered by chemicals. And the cohesion thing is squeezed by a screw press. The squeezed liquid from the cohesion thing is treated with drill drain together. The drill drain is thickened being heated, and thickened drill drain is treated with waste mud together. The solid squeezed from waste mud and the cuttings are stabilized with cement. In this way, the Waste Mud Treatment Syst","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"300 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133712575","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 : 2006-05-16DOI: 10.1109/OCEANSAP.2006.4393872
R. Bahl, T. Ura, H. Sugimatsu, T. Inoue, T. Sakamaki, Junichi Kojima, Tomonari Akamatsu, H. Takahashi, S. Behera, A. Pattnaik, Muntaz Khan, S. Kar
Irrawaddy dolphins (Orcaella brevirostris) being on top of the food chain are considered as a flagship species of Chilika. These cetaceans produce characteristic echolocation pulses that make them acoustically visible, night or day. Acoustic-based survey methods are found to be indispensable for surveying porpoises and dolphins in coastal precincts. This paper reports the first such collaborative attempt in Chilika by applying acoustic survey technology based on the design of an innovative compact and portable acoustic survey device designed for observation of groups of small cetaceans. The acoustic sensor system is housed in a "bird-cage" structure containing 3 hydrophones forming a main linear array, together with two more hydrophones forming a small 3-element triangle array with the central hydrophone, in a plane perpendicular to the linear array axis. It weighs 25 kg and is 3.6 m long, 30 cm in diameter, and can be deployed either vertically or horizontally with buoys and a weight. A high-speed multichannel data acquisition system records the dolphin click sounds from all hydrophones. Signal processing algorithms have been developed for automatic detection and discrimination of echolocation clicks from other underwater sounds, localization of sound sources, and tracking individual animals. The device has previously been tested in vertical mode in a quasi-natural environment with a group of bottlenose dolphins that has confirmed its capability to precisely track several vocalizing animals. The depth of the Chilika lagoon in the dolphin habitat can be as shallow as 1.5 m. Thus, the array has to be deployed in horizontal mode, which enables it to provide very good lateral resolution in the broadside direction. This paper reports the first results of using this array in shallow water conditions. Movements of several Irrawaddy dolphins have been observed very clearly.
{"title":"Acoustic Survey Of Irrawaddy Dolphin Populations In Chilika Lagoon: First Test Of A Compact High-Resolution Device","authors":"R. Bahl, T. Ura, H. Sugimatsu, T. Inoue, T. Sakamaki, Junichi Kojima, Tomonari Akamatsu, H. Takahashi, S. Behera, A. Pattnaik, Muntaz Khan, S. Kar","doi":"10.1109/OCEANSAP.2006.4393872","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393872","url":null,"abstract":"Irrawaddy dolphins (Orcaella brevirostris) being on top of the food chain are considered as a flagship species of Chilika. These cetaceans produce characteristic echolocation pulses that make them acoustically visible, night or day. Acoustic-based survey methods are found to be indispensable for surveying porpoises and dolphins in coastal precincts. This paper reports the first such collaborative attempt in Chilika by applying acoustic survey technology based on the design of an innovative compact and portable acoustic survey device designed for observation of groups of small cetaceans. The acoustic sensor system is housed in a \"bird-cage\" structure containing 3 hydrophones forming a main linear array, together with two more hydrophones forming a small 3-element triangle array with the central hydrophone, in a plane perpendicular to the linear array axis. It weighs 25 kg and is 3.6 m long, 30 cm in diameter, and can be deployed either vertically or horizontally with buoys and a weight. A high-speed multichannel data acquisition system records the dolphin click sounds from all hydrophones. Signal processing algorithms have been developed for automatic detection and discrimination of echolocation clicks from other underwater sounds, localization of sound sources, and tracking individual animals. The device has previously been tested in vertical mode in a quasi-natural environment with a group of bottlenose dolphins that has confirmed its capability to precisely track several vocalizing animals. The depth of the Chilika lagoon in the dolphin habitat can be as shallow as 1.5 m. Thus, the array has to be deployed in horizontal mode, which enables it to provide very good lateral resolution in the broadside direction. This paper reports the first results of using this array in shallow water conditions. Movements of several Irrawaddy dolphins have been observed very clearly.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121734525","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 : 2006-05-16DOI: 10.1109/OCEANSAP.2006.4393849
Xiaoxing Guo, M. Frater, M. Ryan
Underwater acoustic sensor networks can be employed by a vast range of applications, retrieving accurate and up-to-date information from underneath the water surface. Although widely used by radios in terrestrial sensor networks, radio frequencies do not propagate well underwater. Acoustic channels are therefore employed as an alternative to support long-distance and low-power communication underwater, even though such channels suffer from long propagation delay and very limited bandwidth. In this paper, we investigate the impact of the large propagation delay on the throughput of selected classical MAC protocols and their variants, and show that protocols need to be revised to accommodate large propagation delay in order to achieve good throughput. We then introduce a propagation-delay-tolerant collision avoidance protocol named PCAP and show that by taking into account the propagation delay, PCAP offers higher throughput than the protocols that are widely used by conventional wireless communication networks.
{"title":"A Propagation-delay-tolerant Collision Avoidance Protocol for Underwater Acoustic Sensor Networks","authors":"Xiaoxing Guo, M. Frater, M. Ryan","doi":"10.1109/OCEANSAP.2006.4393849","DOIUrl":"https://doi.org/10.1109/OCEANSAP.2006.4393849","url":null,"abstract":"Underwater acoustic sensor networks can be employed by a vast range of applications, retrieving accurate and up-to-date information from underneath the water surface. Although widely used by radios in terrestrial sensor networks, radio frequencies do not propagate well underwater. Acoustic channels are therefore employed as an alternative to support long-distance and low-power communication underwater, even though such channels suffer from long propagation delay and very limited bandwidth. In this paper, we investigate the impact of the large propagation delay on the throughput of selected classical MAC protocols and their variants, and show that protocols need to be revised to accommodate large propagation delay in order to achieve good throughput. We then introduce a propagation-delay-tolerant collision avoidance protocol named PCAP and show that by taking into account the propagation delay, PCAP offers higher throughput than the protocols that are widely used by conventional wireless communication networks.","PeriodicalId":268341,"journal":{"name":"OCEANS 2006 - Asia Pacific","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131133382","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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