Pub Date : 2014-04-07DOI: 10.1109/OCEANS-TAIPEI.2014.6964339
Nawid Jamali, Petar Kormushev, S. Ahmadzadeh, D. Caldwell
In this paper we propose covariance analysis as a metric for reinforcement learning to improve the robustness of a learned policy. The local optima found during the exploration are analyzed in terms of the total cumulative reward and the local behavior of the system in the neighborhood of the optima. The analysis is performed in the solution space to select a policy that exhibits robustness in uncertain and noisy environments. We demonstrate the utility of the method using our previously developed system where an autonomous underwater vehicle (AUV) has to recover from a thruster failure [1]. When a failure is detected the recovery system is invoked, which uses simulations to learn a new controller that utilizes the remaining functioning thrusters to achieve the goal of the AUV, that is, to reach a target position. In this paper, we use covariance analysis to examine the performance of the top, n, policies output by the previous algorithm. We propose a scoring metric that uses the output of the covariance analysis, the time it takes the AUV to reach the target position and the distance between the target position and the AUV's final position. The top polices are simulated in a noisy environment and evaluated using the proposed scoring metric to analyze the effect of noise on their performance. The policy that exhibits more tolerance to noise is selected. We show experimental results where covariance analysis successfully selects a more robust policy that was ranked lower by the original algorithm.
{"title":"Covariance analysis as a measure of policy robustness","authors":"Nawid Jamali, Petar Kormushev, S. Ahmadzadeh, D. Caldwell","doi":"10.1109/OCEANS-TAIPEI.2014.6964339","DOIUrl":"https://doi.org/10.1109/OCEANS-TAIPEI.2014.6964339","url":null,"abstract":"In this paper we propose covariance analysis as a metric for reinforcement learning to improve the robustness of a learned policy. The local optima found during the exploration are analyzed in terms of the total cumulative reward and the local behavior of the system in the neighborhood of the optima. The analysis is performed in the solution space to select a policy that exhibits robustness in uncertain and noisy environments. We demonstrate the utility of the method using our previously developed system where an autonomous underwater vehicle (AUV) has to recover from a thruster failure [1]. When a failure is detected the recovery system is invoked, which uses simulations to learn a new controller that utilizes the remaining functioning thrusters to achieve the goal of the AUV, that is, to reach a target position. In this paper, we use covariance analysis to examine the performance of the top, n, policies output by the previous algorithm. We propose a scoring metric that uses the output of the covariance analysis, the time it takes the AUV to reach the target position and the distance between the target position and the AUV's final position. The top polices are simulated in a noisy environment and evaluated using the proposed scoring metric to analyze the effect of noise on their performance. The policy that exhibits more tolerance to noise is selected. We show experimental results where covariance analysis successfully selects a more robust policy that was ranked lower by the original algorithm.","PeriodicalId":114739,"journal":{"name":"OCEANS 2014 - TAIPEI","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116767822","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 : 2014-04-07DOI: 10.1109/OCEANS-TAIPEI.2014.6964558
F. Chiu, Wen-Fu Li, Wen-Chuan Tiao
Rising fuel prices and regulations to reduce CO2 emission have become a strong driving force to push shipyards and ship owners to build and operate energy saving ships. To meet these increasing demands, many novel designs and devices have been developed for reducing drag or for improving propulsion efficiency of a ship in seaway. Furthermore, several approaches using passive or active oscillating fin to extract wave power to assist ship propulsion have also been explored. The objective of the present study is to investigate the feasibility of a concept using an active pitch-oscillating fin to harness wave power for propulsion enhancement of merchant ships. Experimental data of the NACA 0012 oscillating foil are adopted to validate the present CFD simulation. Dependence of propulsion performance on Reynolds number and submerged depth are investigated. It has been confirmed that thrust of a flapping fin increases but efficiency decreases with larger Reynolds number, and shallower submerged depth of fin has negative effect for propulsion. Through simulations, thrust and propulsion efficiency of a flapping fin equipped at bow in full-scale ship are assessed. An active pitch-oscillating fin together with heave motion driven by ship vertical response to waves may generate significant amount of thrust with relatively high efficiency. As an example shown in the paper, for a VLCC of 321 meter long, a bow fin with projected area to waterline area ratio of 1/143, pitching actively around its pivot axis, may save energy about 3.1%~9.5% in the ship speed ranges of 12~16.5 knot.
{"title":"Preliminary study on a concept of wave propulsion by an active pitch-oscillating fin","authors":"F. Chiu, Wen-Fu Li, Wen-Chuan Tiao","doi":"10.1109/OCEANS-TAIPEI.2014.6964558","DOIUrl":"https://doi.org/10.1109/OCEANS-TAIPEI.2014.6964558","url":null,"abstract":"Rising fuel prices and regulations to reduce CO2 emission have become a strong driving force to push shipyards and ship owners to build and operate energy saving ships. To meet these increasing demands, many novel designs and devices have been developed for reducing drag or for improving propulsion efficiency of a ship in seaway. Furthermore, several approaches using passive or active oscillating fin to extract wave power to assist ship propulsion have also been explored. The objective of the present study is to investigate the feasibility of a concept using an active pitch-oscillating fin to harness wave power for propulsion enhancement of merchant ships. Experimental data of the NACA 0012 oscillating foil are adopted to validate the present CFD simulation. Dependence of propulsion performance on Reynolds number and submerged depth are investigated. It has been confirmed that thrust of a flapping fin increases but efficiency decreases with larger Reynolds number, and shallower submerged depth of fin has negative effect for propulsion. Through simulations, thrust and propulsion efficiency of a flapping fin equipped at bow in full-scale ship are assessed. An active pitch-oscillating fin together with heave motion driven by ship vertical response to waves may generate significant amount of thrust with relatively high efficiency. As an example shown in the paper, for a VLCC of 321 meter long, a bow fin with projected area to waterline area ratio of 1/143, pitching actively around its pivot axis, may save energy about 3.1%~9.5% in the ship speed ranges of 12~16.5 knot.","PeriodicalId":114739,"journal":{"name":"OCEANS 2014 - TAIPEI","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116901699","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 : 2014-04-07DOI: 10.1109/OCEANS-TAIPEI.2014.6964364
Jinghua Tao, Xu Jia, Jinlin Hou, Zhaoyang Wang
Jack-up drilling platform is supported by spud-can foundations penetrated into the submarine soil layer for drilling new wells or work-over of existing facilities. When the jack-up drilling platform is positioned close to the adjacent platform pile foundation, the soil movement resulting from the spud-can penetration can induce significant loads on the piles. Especially when the working jack-up drilling platform suffers an extreme storm, the pile foundation strands the dangerous condition. The paper analysis the conclusions and disadvantages of the current studies, and then presents a new method for the coupling effect analysis of penetration pressing and environment load. Then this paper explains the solution by the example applied in the offshore practice.
{"title":"Research of the coupling effect of span-can penetration and environmental loads on piles","authors":"Jinghua Tao, Xu Jia, Jinlin Hou, Zhaoyang Wang","doi":"10.1109/OCEANS-TAIPEI.2014.6964364","DOIUrl":"https://doi.org/10.1109/OCEANS-TAIPEI.2014.6964364","url":null,"abstract":"Jack-up drilling platform is supported by spud-can foundations penetrated into the submarine soil layer for drilling new wells or work-over of existing facilities. When the jack-up drilling platform is positioned close to the adjacent platform pile foundation, the soil movement resulting from the spud-can penetration can induce significant loads on the piles. Especially when the working jack-up drilling platform suffers an extreme storm, the pile foundation strands the dangerous condition. The paper analysis the conclusions and disadvantages of the current studies, and then presents a new method for the coupling effect analysis of penetration pressing and environment load. Then this paper explains the solution by the example applied in the offshore practice.","PeriodicalId":114739,"journal":{"name":"OCEANS 2014 - TAIPEI","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116748082","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 : 2014-04-07DOI: 10.1109/OCEANS-TAIPEI.2014.6964571
Chau-Chang Wang, Hsin-Hung Chen, Kun-Hung Li
During deep sea exploration, the motion of the deep tow system is influenced by that of the surface vessel, the change of the cable length and the current field in the water column. Though the towing vessel moves in a straight line on the sea surface, the heading of the tow body is not necessary collinear to the towing direction. If no devices are available to adjust the direction of the tow body, data collected by directional sensors, like camera or side scan sonar, will be skewed. It causes problems and difficulties in the post processing for mosaicing data sets into a map of a larger area. Moreover, the existence of the offset angle creates a staircase-like pattern on the map when the images are stitched together. The staircase pattern hampers the continuity of the data. The offset angle, in theory, can be computed from the USBL and the compass readings. But in practice, the refresh rates of USBL and the compass are not compatible such that the results are not good enough for maneuvering the tow system. In this paper, we propose using the feature points on the images acquired to estimate the offset angle of the tow system with respect to the trace of the motion. The computation is carried out with the OPENCV library implemented in Visual C. Currently, the refresh rate can be about 2 Hz with 30 fps camera acquisition, given the tow body is moving with 0.5 m/s speed.
{"title":"Image-based motion estimation of underwater tow body","authors":"Chau-Chang Wang, Hsin-Hung Chen, Kun-Hung Li","doi":"10.1109/OCEANS-TAIPEI.2014.6964571","DOIUrl":"https://doi.org/10.1109/OCEANS-TAIPEI.2014.6964571","url":null,"abstract":"During deep sea exploration, the motion of the deep tow system is influenced by that of the surface vessel, the change of the cable length and the current field in the water column. Though the towing vessel moves in a straight line on the sea surface, the heading of the tow body is not necessary collinear to the towing direction. If no devices are available to adjust the direction of the tow body, data collected by directional sensors, like camera or side scan sonar, will be skewed. It causes problems and difficulties in the post processing for mosaicing data sets into a map of a larger area. Moreover, the existence of the offset angle creates a staircase-like pattern on the map when the images are stitched together. The staircase pattern hampers the continuity of the data. The offset angle, in theory, can be computed from the USBL and the compass readings. But in practice, the refresh rates of USBL and the compass are not compatible such that the results are not good enough for maneuvering the tow system. In this paper, we propose using the feature points on the images acquired to estimate the offset angle of the tow system with respect to the trace of the motion. The computation is carried out with the OPENCV library implemented in Visual C. Currently, the refresh rate can be about 2 Hz with 30 fps camera acquisition, given the tow body is moving with 0.5 m/s speed.","PeriodicalId":114739,"journal":{"name":"OCEANS 2014 - TAIPEI","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115527411","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 : 2014-04-07DOI: 10.1109/OCEANS-TAIPEI.2014.6964285
L. Defu, Liu Guilin, Shi Hongda, Wang Fengqing, Chen Ziyu
With the global warming and sea level rising, the frequency and intensity of extreme external natural hazards would increase. Face to the increasing tendency of extreme meteorological hazards the typhoon /hurricane/tropical cyclone triggered disasters are the most important factors influencing the economic development and millions of people in Asia, American and Australia countries. This paper introduced our proposed Compound Extreme Value Distribution (CEVD), Multivariate Compound Extreme Value Distribution (MCEVD) and compared it with some traditional design codes in China, API, DNV and IAEA for coastal defense infrastructures and offshore structures against typhoon/hurricane attacks. 2005 hurricane Katrina, Rita disaster in New Orleans, Gulf of Mexico sea areas, 2012 hurricane Sandy disaster in New York - New Jersey areas and 2013 typhoon Fitow disaster in China not only proved our proposed CEVD in 1982, but also proved 2006 proposed MCEVD predicted results in mentioned above areas.
{"title":"Extreme sea hazards statistics and engineering applications","authors":"L. Defu, Liu Guilin, Shi Hongda, Wang Fengqing, Chen Ziyu","doi":"10.1109/OCEANS-TAIPEI.2014.6964285","DOIUrl":"https://doi.org/10.1109/OCEANS-TAIPEI.2014.6964285","url":null,"abstract":"With the global warming and sea level rising, the frequency and intensity of extreme external natural hazards would increase. Face to the increasing tendency of extreme meteorological hazards the typhoon /hurricane/tropical cyclone triggered disasters are the most important factors influencing the economic development and millions of people in Asia, American and Australia countries. This paper introduced our proposed Compound Extreme Value Distribution (CEVD), Multivariate Compound Extreme Value Distribution (MCEVD) and compared it with some traditional design codes in China, API, DNV and IAEA for coastal defense infrastructures and offshore structures against typhoon/hurricane attacks. 2005 hurricane Katrina, Rita disaster in New Orleans, Gulf of Mexico sea areas, 2012 hurricane Sandy disaster in New York - New Jersey areas and 2013 typhoon Fitow disaster in China not only proved our proposed CEVD in 1982, but also proved 2006 proposed MCEVD predicted results in mentioned above areas.","PeriodicalId":114739,"journal":{"name":"OCEANS 2014 - TAIPEI","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114309751","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 : 2014-04-07DOI: 10.1109/OCEANS-TAIPEI.2014.6964355
Gilad Avrashi, Shlomi Museri, Yaakov Bucris, Azriel Sinai, A. Amar
We introduce a low data rate video compression scheme for underwater acoustic communication. Recently, multi-carrier based underwater acoustic modems have been proposed and tested for data rates of up to tens of kilobits-per-second for about 1-4 kilometers transmission range. Online transmission of video data using these rates requires extreme compression. Herein, we propose pre-encoder and post-decoder processing in order to reduce the data rate. This is done by exploiting the characteristics of underwater videos for excluding frames. The algorithm was tested and analyzed in simulation environment with several video samples taken by divers in shallow waters of the Mediterranean. We show that using this technique, increased performance is achieved compared to standard H.264/AVC based codecs in both objective and subjective terms.
{"title":"Underwater video streaming using adaptive frame decimation","authors":"Gilad Avrashi, Shlomi Museri, Yaakov Bucris, Azriel Sinai, A. Amar","doi":"10.1109/OCEANS-TAIPEI.2014.6964355","DOIUrl":"https://doi.org/10.1109/OCEANS-TAIPEI.2014.6964355","url":null,"abstract":"We introduce a low data rate video compression scheme for underwater acoustic communication. Recently, multi-carrier based underwater acoustic modems have been proposed and tested for data rates of up to tens of kilobits-per-second for about 1-4 kilometers transmission range. Online transmission of video data using these rates requires extreme compression. Herein, we propose pre-encoder and post-decoder processing in order to reduce the data rate. This is done by exploiting the characteristics of underwater videos for excluding frames. The algorithm was tested and analyzed in simulation environment with several video samples taken by divers in shallow waters of the Mediterranean. We show that using this technique, increased performance is achieved compared to standard H.264/AVC based codecs in both objective and subjective terms.","PeriodicalId":114739,"journal":{"name":"OCEANS 2014 - TAIPEI","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115142950","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 : 2014-04-07DOI: 10.1109/OCEANS-TAIPEI.2014.6964447
H. Matsumoto, E. Araki, K. Kawaguchi, S. Nishida, Y. Kaneda
DONET, i.e., the dense ocean-floor network system for earthquakes and tsunamis has started its operation in the Nankai Trough, SW Japan in the early of 2010, and followed by the extension to the westward region as DONET2 in near future. DONET observatory is composed of various sensors such as broadband seismometer, seismic accelerometer, tsunami meter, etc. The present study focuses on quartz pressure gauges being used as tsunami meters measuring water pressure change. In the present study, long-term pressure gauges' characteristics have been evaluated by using the JAMSTEC's high accuracy pressure standard before deploying into the deep-sea. The high accuracy pressure standard is mainly customized by a piston gauge, a pressure generator/controller, a reference pressure monitor, and a thermal controlled large capacity chamber, which virtually reproduces the deep-sea environment. 20 MPa hydraulic pressure was applied to the pressure gauges under the constant temperature of 2°C, which is equivalent to the ocean-bottom of 2,000 meters depth for the duration of approximately one month. As a result, sensors' drift varies among pressure gauges, however, which implies that the gradual drift possibly occurs a few centimeters per month in maximum. We also discuss the sensors' drift after deploying the deep-sea by analyzing the long-term in-situ observations, which shows that it continues at a rate of a few to ten centimeters per year in the early stage, then it tends to be reduced gradually.
{"title":"Long-term features of quartz pressure gauges inferred from experimental and in-situ observations","authors":"H. Matsumoto, E. Araki, K. Kawaguchi, S. Nishida, Y. Kaneda","doi":"10.1109/OCEANS-TAIPEI.2014.6964447","DOIUrl":"https://doi.org/10.1109/OCEANS-TAIPEI.2014.6964447","url":null,"abstract":"DONET, i.e., the dense ocean-floor network system for earthquakes and tsunamis has started its operation in the Nankai Trough, SW Japan in the early of 2010, and followed by the extension to the westward region as DONET2 in near future. DONET observatory is composed of various sensors such as broadband seismometer, seismic accelerometer, tsunami meter, etc. The present study focuses on quartz pressure gauges being used as tsunami meters measuring water pressure change. In the present study, long-term pressure gauges' characteristics have been evaluated by using the JAMSTEC's high accuracy pressure standard before deploying into the deep-sea. The high accuracy pressure standard is mainly customized by a piston gauge, a pressure generator/controller, a reference pressure monitor, and a thermal controlled large capacity chamber, which virtually reproduces the deep-sea environment. 20 MPa hydraulic pressure was applied to the pressure gauges under the constant temperature of 2°C, which is equivalent to the ocean-bottom of 2,000 meters depth for the duration of approximately one month. As a result, sensors' drift varies among pressure gauges, however, which implies that the gradual drift possibly occurs a few centimeters per month in maximum. We also discuss the sensors' drift after deploying the deep-sea by analyzing the long-term in-situ observations, which shows that it continues at a rate of a few to ten centimeters per year in the early stage, then it tends to be reduced gradually.","PeriodicalId":114739,"journal":{"name":"OCEANS 2014 - TAIPEI","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115353509","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 : 2014-04-07DOI: 10.1109/OCEANS-TAIPEI.2014.6964437
Ran Liao, Hui Ma
In situ marine algae detection is very important for many global issues. Even though polarized-light scattering has the promising application in the biomedical characterization, its potential to detect marine algae is still not clear. The movements of the suspended marine algae due to their own migrations, arise challenges for the polarization measurement and information acquisition. In this paper, we response the challenges and show the potential of the polarized-light scattering to detect the marine algae. We measure the scattering signals of the aqueous suspension of the glass fibers by use of a 2-channel simultaneous polarization measurement setup and describe the properties of the signals. After comparing and analyzing of the polarizations of glass fibers with different orientations, we reveal the ability of polarized-light scattering to retrieve the orientation distribution of the cylindrical scatterers of the sample, and show the method's potential to detect the marine algae.
{"title":"Probing the suspended marine algae using polarized-light scattering","authors":"Ran Liao, Hui Ma","doi":"10.1109/OCEANS-TAIPEI.2014.6964437","DOIUrl":"https://doi.org/10.1109/OCEANS-TAIPEI.2014.6964437","url":null,"abstract":"In situ marine algae detection is very important for many global issues. Even though polarized-light scattering has the promising application in the biomedical characterization, its potential to detect marine algae is still not clear. The movements of the suspended marine algae due to their own migrations, arise challenges for the polarization measurement and information acquisition. In this paper, we response the challenges and show the potential of the polarized-light scattering to detect the marine algae. We measure the scattering signals of the aqueous suspension of the glass fibers by use of a 2-channel simultaneous polarization measurement setup and describe the properties of the signals. After comparing and analyzing of the polarizations of glass fibers with different orientations, we reveal the ability of polarized-light scattering to retrieve the orientation distribution of the cylindrical scatterers of the sample, and show the method's potential to detect the marine algae.","PeriodicalId":114739,"journal":{"name":"OCEANS 2014 - TAIPEI","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125965897","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 : 2014-04-07DOI: 10.1109/OCEANS-TAIPEI.2014.6964333
B. Tian, Jiancheng Yu, Aiqun Zhang, Fumin Zhang, Zhier Chen, K. Sun
Wave-driven unmanned surface vehicle (WUSV) is a great success of application of solar and wave energy in the ocean robot. In this paper, the nonlinear dynamic model of WUSV in two dimension is established based on the analysis of its driving principle in the longitudinal profile. Then, we calculate the wave and driving force, and determine hydrodynamic coefficients according to the empirical data and experimental platform of WUSV. Finally, we simplify the nonlinear equations and present the simulation results of the model.
{"title":"Dynamics analysis of wave-driven unmanned surface vehicle in longitudinal profile","authors":"B. Tian, Jiancheng Yu, Aiqun Zhang, Fumin Zhang, Zhier Chen, K. Sun","doi":"10.1109/OCEANS-TAIPEI.2014.6964333","DOIUrl":"https://doi.org/10.1109/OCEANS-TAIPEI.2014.6964333","url":null,"abstract":"Wave-driven unmanned surface vehicle (WUSV) is a great success of application of solar and wave energy in the ocean robot. In this paper, the nonlinear dynamic model of WUSV in two dimension is established based on the analysis of its driving principle in the longitudinal profile. Then, we calculate the wave and driving force, and determine hydrodynamic coefficients according to the empirical data and experimental platform of WUSV. Finally, we simplify the nonlinear equations and present the simulation results of the model.","PeriodicalId":114739,"journal":{"name":"OCEANS 2014 - TAIPEI","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127305081","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 : 2014-04-07DOI: 10.1109/OCEANS-TAIPEI.2014.6964326
S. H. Huang, T. C. Yang, J. Tsao
For communications, the estimated symbols (the output of a channel equalizer) is sometimes referred to as soft-estimate of the (transmitted) symbols. The mean squared Euclidian distribution between the soft symbol and true symbols yields the mean squared symbol estimation error, sometimes referred to as the soft-decision error. The soft symbol distribution is a key measure of the equalizer performance and is used for calculating the probability of bit errors. In this paper, we apply a channel estimation (CE) based decision feedback equalizer (DFE) to at sea data. For CE-DFE, we assume channel estimation in the training mode to avoid the error feedback problem that often occurs in real data processing. The reason is to study the relationship between equalizer performance and channel estimation performance without the error feedback problem. Specifically, we investigate the relation between the soft-decision error and signal prediction error; the latter is used as a measure for the channel estimation error. For channel estimation, we used various algorithms based on signal subspace tracking as well as conventional full space tracking. For each channel estimation algorithm, we estimate the symbol distribution. We find the distributions of the soft-estimate symbols are well fitted by a Gaussian normal distribution, with a variance predictable by the signal prediction error.
{"title":"Distributions of soft-decision symbols using channel-estimation based equalizers","authors":"S. H. Huang, T. C. Yang, J. Tsao","doi":"10.1109/OCEANS-TAIPEI.2014.6964326","DOIUrl":"https://doi.org/10.1109/OCEANS-TAIPEI.2014.6964326","url":null,"abstract":"For communications, the estimated symbols (the output of a channel equalizer) is sometimes referred to as soft-estimate of the (transmitted) symbols. The mean squared Euclidian distribution between the soft symbol and true symbols yields the mean squared symbol estimation error, sometimes referred to as the soft-decision error. The soft symbol distribution is a key measure of the equalizer performance and is used for calculating the probability of bit errors. In this paper, we apply a channel estimation (CE) based decision feedback equalizer (DFE) to at sea data. For CE-DFE, we assume channel estimation in the training mode to avoid the error feedback problem that often occurs in real data processing. The reason is to study the relationship between equalizer performance and channel estimation performance without the error feedback problem. Specifically, we investigate the relation between the soft-decision error and signal prediction error; the latter is used as a measure for the channel estimation error. For channel estimation, we used various algorithms based on signal subspace tracking as well as conventional full space tracking. For each channel estimation algorithm, we estimate the symbol distribution. We find the distributions of the soft-estimate symbols are well fitted by a Gaussian normal distribution, with a variance predictable by the signal prediction error.","PeriodicalId":114739,"journal":{"name":"OCEANS 2014 - TAIPEI","volume":"499 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122202343","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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