Pub Date : 2003-06-01DOI: 10.2534/JJASNAOE1968.2003.193_85
Yoshihiko Tango, M. Ishiyama, Syouji Nagahara, Tomoki Nagashima, Jun Kobayashi
In many shipyards, shell plates having complex curvature are formed using line heating or a combination of line heating and cold forming. These processes are effective but labor intensive. In this paper, we describe a new system that plans and carries out line heating automatically. This system, called IHI-Alpha, projects the desired curved geometry onto the original flat plate, and calculates a heating plan which includes the travel and heat input rate of the heating head. Once calculated, this heating plan is forwarded to a special shop workstation where the final curved form is then produced directly, with no iteration. This differs from the conventional process which is based on operator experience plus trial-and-error.The IHI-Alpha system has been employed in the construction of a number of vessels including bulk carriers, VLCC's, and containerships. In this paper, we introduce the system, its theoretical foundation, and how it works including both software and hardware aspects. Examples of its use in actual ship production are described. Finally, ideas for future development of this technology are discussed.
{"title":"Automated Line Heating for Plate Forming by IHI-ALPHA System and its Application to Construction of Actual Vessels","authors":"Yoshihiko Tango, M. Ishiyama, Syouji Nagahara, Tomoki Nagashima, Jun Kobayashi","doi":"10.2534/JJASNAOE1968.2003.193_85","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2003.193_85","url":null,"abstract":"In many shipyards, shell plates having complex curvature are formed using line heating or a combination of line heating and cold forming. These processes are effective but labor intensive. In this paper, we describe a new system that plans and carries out line heating automatically. This system, called IHI-Alpha, projects the desired curved geometry onto the original flat plate, and calculates a heating plan which includes the travel and heat input rate of the heating head. Once calculated, this heating plan is forwarded to a special shop workstation where the final curved form is then produced directly, with no iteration. This differs from the conventional process which is based on operator experience plus trial-and-error.The IHI-Alpha system has been employed in the construction of a number of vessels including bulk carriers, VLCC's, and containerships. In this paper, we introduce the system, its theoretical foundation, and how it works including both software and hardware aspects. Examples of its use in actual ship production are described. Finally, ideas for future development of this technology are discussed.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130319877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-01DOI: 10.2534/JJASNAOE1968.2002.15
T. Nagamatsu, Y. Kodama, A. Kakugawa, M. Takai, K. Murakami, S. Ishikawa, H. Kamiirisa, S. Ogiwara, Y. Yoshida, Toshio Suzuki, Y. Toda, H. Kato, A. Ikemoto, Shuji Yamatani, S. Imo, K. Yamashita
This paper is the second half of the report on the study on microbubbles carried out by the SR239 project of the Shipbuilding Research Association of Japan, and describes the full-scale experiment using “SEIUN MARU”, a 116m-long training ship that belongs to the Institute for Sea Training. Using numerical analysis and the experimental data obtained in the preparatory study described in the first half of the report, the net energy saving of SEIUN MARU by microbubbles at 14kts was estimated to be 2%. In the full-scale experiment, the trajectory of the generated bubbles was observed using underwater TV cameras and was found to shift more upward than predicted. The local skin friction was measured at several locations on the hull surface, and the skin friction increase as well as decrease by the bubbles was measured. The local void ratio was measured at one point on the hull surface, and the bubbles were found to travel slightly away from the hull surface. The change of the ship speed and shaft horsepower by microbubbles was measured, and the decrease or increase of engine power at constant ship speed was analyzed. In the most cases of the experiment the ship speed decreased by the bubble injection, mainly due to the increase of ship resistance and the decrease of propeller efficiency caused by the bubbles going into the working propeller. But, by carefully choosing the bubble injection location and thus avoiding the bubble entrainment into the propeller, the 3% power saving at a constant speed of 14kts was obtained. By taking into account the power needed to inject bubbles against hydrostatic pressure due to water depth at the injection point, this corresponds to the net power saving of 2%. Thus the net power saving by microbubbles was measured on a full- scale ship for the first time in the world.
{"title":"A Full-scale Experiment on Microbubbles for Skin Friction Reduction Using \"SEIUN MARU\"","authors":"T. Nagamatsu, Y. Kodama, A. Kakugawa, M. Takai, K. Murakami, S. Ishikawa, H. Kamiirisa, S. Ogiwara, Y. Yoshida, Toshio Suzuki, Y. Toda, H. Kato, A. Ikemoto, Shuji Yamatani, S. Imo, K. Yamashita","doi":"10.2534/JJASNAOE1968.2002.15","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2002.15","url":null,"abstract":"This paper is the second half of the report on the study on microbubbles carried out by the SR239 project of the Shipbuilding Research Association of Japan, and describes the full-scale experiment using “SEIUN MARU”, a 116m-long training ship that belongs to the Institute for Sea Training. Using numerical analysis and the experimental data obtained in the preparatory study described in the first half of the report, the net energy saving of SEIUN MARU by microbubbles at 14kts was estimated to be 2%. In the full-scale experiment, the trajectory of the generated bubbles was observed using underwater TV cameras and was found to shift more upward than predicted. The local skin friction was measured at several locations on the hull surface, and the skin friction increase as well as decrease by the bubbles was measured. The local void ratio was measured at one point on the hull surface, and the bubbles were found to travel slightly away from the hull surface. The change of the ship speed and shaft horsepower by microbubbles was measured, and the decrease or increase of engine power at constant ship speed was analyzed. In the most cases of the experiment the ship speed decreased by the bubble injection, mainly due to the increase of ship resistance and the decrease of propeller efficiency caused by the bubbles going into the working propeller. But, by carefully choosing the bubble injection location and thus avoiding the bubble entrainment into the propeller, the 3% power saving at a constant speed of 14kts was obtained. By taking into account the power needed to inject bubbles against hydrostatic pressure due to water depth at the injection point, this corresponds to the net power saving of 2%. Thus the net power saving by microbubbles was measured on a full- scale ship for the first time in the world.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114448960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-01DOI: 10.2534/JJASNAOE1968.2002.227
T. Ikoma, K. Masuda, H. Maeda, C. Rheem
There are some studies on reduction of hyclroelaastic deflection of a very large floating structure. However, the wave drifting force increases when the deflection is reduced. It is very difficult to reduce the deflection and the wave drifting force at the same time.This paper proposes an aircushion-supported type for a very large floating structure. This type may be able to reduce the deflection and the wave drifting force simultaneously. Therefore, we show the theoretical analysis method for the hydrodynamic force of the aircushion-supported flexible floating structure. This analysis method is based on the pressure distribution method. The free water surface condition in the aircushion is satisfied when the boundary problem is solved in this method.In this paper, the deflection characteristic and the water elevation in the aircushion and around the structure are shown. We discuss them. Moreover., the calculation results by the pressure distribution method and the three-dimensional analysis based on the singular point distribution method are compared in order to prove validity of the program code and the corresponding theory.
{"title":"A Fundamental Study on Hydroelastic Behaviors of Large Aircushion Supported Flexible Floating Structures in Regular Waves","authors":"T. Ikoma, K. Masuda, H. Maeda, C. Rheem","doi":"10.2534/JJASNAOE1968.2002.227","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2002.227","url":null,"abstract":"There are some studies on reduction of hyclroelaastic deflection of a very large floating structure. However, the wave drifting force increases when the deflection is reduced. It is very difficult to reduce the deflection and the wave drifting force at the same time.This paper proposes an aircushion-supported type for a very large floating structure. This type may be able to reduce the deflection and the wave drifting force simultaneously. Therefore, we show the theoretical analysis method for the hydrodynamic force of the aircushion-supported flexible floating structure. This analysis method is based on the pressure distribution method. The free water surface condition in the aircushion is satisfied when the boundary problem is solved in this method.In this paper, the deflection characteristic and the water elevation in the aircushion and around the structure are shown. We discuss them. Moreover., the calculation results by the pressure distribution method and the three-dimensional analysis based on the singular point distribution method are compared in order to prove validity of the program code and the corresponding theory.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124671375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-01DOI: 10.2534/JJASNAOE1968.2002.289
Y. Inoue, Mir Tareque Ali
Wave drift forces play an important role when a vessel is floating in the vicinity of another vessel or, floating structure. The numerical accuracy in the computation of the wave exciting forces and the hydrodynamic forces of multiple floating bodies influences the motion response that eventually affects the second order wave drift forces of each floating body. The present study is based on the far-field method where the velocity potential is calculated by 3D sink-source technique. In order to justify the validity of the present calculations, some comparisons are made for simple multi-body floating systems like multiple floating cylinders and cylindrical body with box shaped body. The numerical calculations have been investigated for a parallel arrangement of FPSO and an LNG carrier. The computations of motion responses and drift forces are carried out for a number of different wave heading angles and for different separation distances between the FPSO and LNG carrier. The numerical results are compared with the experimental ones as well as with previous computations to illustrate the improved numerical accuracy of the present computations. It has been observed that due to the lack of accuracy in the numerical scheme adopted for the computer code, the computed results of drift forces sometimes shows completely opposite trend than that of the experimental ones.
{"title":"A STUDY ON NUMERICAL ACCURACY FOR THE PREDICTION OF MOTION RESPONSES AND DRIFT FORCES OF MULTIPLE FLOATING BODIES","authors":"Y. Inoue, Mir Tareque Ali","doi":"10.2534/JJASNAOE1968.2002.289","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2002.289","url":null,"abstract":"Wave drift forces play an important role when a vessel is floating in the vicinity of another vessel or, floating structure. The numerical accuracy in the computation of the wave exciting forces and the hydrodynamic forces of multiple floating bodies influences the motion response that eventually affects the second order wave drift forces of each floating body. The present study is based on the far-field method where the velocity potential is calculated by 3D sink-source technique. In order to justify the validity of the present calculations, some comparisons are made for simple multi-body floating systems like multiple floating cylinders and cylindrical body with box shaped body. The numerical calculations have been investigated for a parallel arrangement of FPSO and an LNG carrier. The computations of motion responses and drift forces are carried out for a number of different wave heading angles and for different separation distances between the FPSO and LNG carrier. The numerical results are compared with the experimental ones as well as with previous computations to illustrate the improved numerical accuracy of the present computations. It has been observed that due to the lack of accuracy in the numerical scheme adopted for the computer code, the computed results of drift forces sometimes shows completely opposite trend than that of the experimental ones.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121750829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-01DOI: 10.2534/JJASNAOE1968.2002.367
M. Harada, M. Fujikubo
A series of buckling eigen-value calculations and elastoplastic large deflection analyses of simply upported continuous plate with cutout under thrust has been performed. Firstly, simple formulae for estimation of elastic buckling strength have been derived based on the results of eigen-value calculations. Secondary, it has been clarified that the buckling strength evaluated by the existing plastic correction methods exceeds the ultimate strength in some combinations of plate thickness and cutout diameter. So, new plastic correction formula considering the yielding effect for estimation of buckling strength of continuous plate with cutout has been proposed. Finally, by focusing on the characteristics of ultimate strength obtained by elastoplastic large deflection analyses, simple formulae for estimation of ultimate strength of continuous plate with cutout have been derived.
{"title":"Estimation of buckling and ultimate strength of continuous plate with cutout under thrust","authors":"M. Harada, M. Fujikubo","doi":"10.2534/JJASNAOE1968.2002.367","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2002.367","url":null,"abstract":"A series of buckling eigen-value calculations and elastoplastic large deflection analyses of simply upported continuous plate with cutout under thrust has been performed. Firstly, simple formulae for estimation of elastic buckling strength have been derived based on the results of eigen-value calculations. Secondary, it has been clarified that the buckling strength evaluated by the existing plastic correction methods exceeds the ultimate strength in some combinations of plate thickness and cutout diameter. So, new plastic correction formula considering the yielding effect for estimation of buckling strength of continuous plate with cutout has been proposed. Finally, by focusing on the characteristics of ultimate strength obtained by elastoplastic large deflection analyses, simple formulae for estimation of ultimate strength of continuous plate with cutout have been derived.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129885528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-01DOI: 10.2534/JJASNAOE1968.2002.247
K. Tanizawa, Makiko Minami, Y. Ogawa, Yasuhira Yamada
As a part of the project study concerning on ship structural design for oil spill prevention by collision, optimal design of flexible bulbous bow structure is studied to absorb kinetic energy of the colliding ship. Such a flexible bulbous bow is named as buffer bow. To formulate design criteria of the buffer bow, the hydrodynamic impact forces acts on the bulbous bow was studied theoretically and experimentally. For theoretical study, shape of the bulbous bow was approximated by an ellipsoid and von Karman's momentum theory was applied to estimate the slamming impact loads with given impact velocity of the emerged bow to free surface. Wagner's impact theory was also applied to study the effect of free surface swell up. Based on the momentum theoy, an estimation method of the impact loads was proposed. To validate the estimation method, a experiment was conducted at the 80m square tank of NMRI. A self-propelling container ship model was used for the experiment. The vertical and lateral shearing forces and bending moments at the root of the bulbous bow were measured. In this paper, the results of the study are presented.
{"title":"Water surface impact loads acts on bulbous bow of ships","authors":"K. Tanizawa, Makiko Minami, Y. Ogawa, Yasuhira Yamada","doi":"10.2534/JJASNAOE1968.2002.247","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2002.247","url":null,"abstract":"As a part of the project study concerning on ship structural design for oil spill prevention by collision, optimal design of flexible bulbous bow structure is studied to absorb kinetic energy of the colliding ship. Such a flexible bulbous bow is named as buffer bow. To formulate design criteria of the buffer bow, the hydrodynamic impact forces acts on the bulbous bow was studied theoretically and experimentally. For theoretical study, shape of the bulbous bow was approximated by an ellipsoid and von Karman's momentum theory was applied to estimate the slamming impact loads with given impact velocity of the emerged bow to free surface. Wagner's impact theory was also applied to study the effect of free surface swell up. Based on the momentum theoy, an estimation method of the impact loads was proposed. To validate the estimation method, a experiment was conducted at the 80m square tank of NMRI. A self-propelling container ship model was used for the experiment. The vertical and lateral shearing forces and bending moments at the root of the bulbous bow were measured. In this paper, the results of the study are presented.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133960676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-01DOI: 10.2534/JJASNAOE1968.2002.377
Noboru Kubo, M. Katuhara, H. Yamato, R. Michida
Domestic shipping companies should decide whether a new or existing line is profitable or not. We propose a method to find profitability for an examining sea line and proper specifications of a ship for it. The method is made of PC programs including an estimating method of cargo demand and calculate a fleet condition, ship specifications and shipping account for a long haul ferry or RORO ship line.
{"title":"A study on determining specifications of vessels and profit of a ship company by an estimation for cargo demand analysis on ferry or RORO-ship lines","authors":"Noboru Kubo, M. Katuhara, H. Yamato, R. Michida","doi":"10.2534/JJASNAOE1968.2002.377","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2002.377","url":null,"abstract":"Domestic shipping companies should decide whether a new or existing line is profitable or not. We propose a method to find profitability for an examining sea line and proper specifications of a ship for it. The method is made of PC programs including an estimating method of cargo demand and calculate a fleet condition, ship specifications and shipping account for a long haul ferry or RORO ship line.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131598842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-01DOI: 10.2534/JJASNAOE1968.2002.397
Yoshihiro Kobayashi, A. Sorensen, T. Uryu
For storage and transport of liquefied gas such as LNG or LH2 (liquefied hydrogen), it is of great importance to reduce the boil off gas to a minimum. The thermal insulation system is playing a significant roll here. Though the specification of tank insulation should be decided by the boil off figure of a desired total system from a view point of an economical and practical use of it, the reduction of evaporated quantity is being demanded stronger, and any achievements to enhance the reduction are appreciated. The authors have introduced a new concept for enhancement of insulation efficiency by indirectly using the cold boil off gas as a protective shield or a heat sink to limit transmission of heat to the tank/cargo. To verify this theory of “vapor insulation system”, an experiment based on cold gas flow was carried out in a small scale apparatus to analyze carefully the effect on the heat transmission with and without cold vapor flow. These results were implemented in a calculation model of a spherical tank for LNG and LH2, and combined with some parameters such as gas flow quantity, gas temperature and location of gas passage. Based on this work realistic examples of design were proposed for a new insulation system. The configuration takes into account the concept of the small leak protection system for MOSS spherical tank. The principle of this new insulation concept proposed is that cold nitrogen gas which is produced by heat-exchange with the boil off LNG or LH2 vapor flows through a small passage created in the insulation structure. The upward flow of cold gas through the annular space around the tank will absorb the heat from the hold space of the cargo tank before it reaches the valuable liquid cargo, and it will simultaneously work as a leak detection system of cargo.
{"title":"Experimental Verification of Vapor Insulation System And Its Application to LNG and LH2 Tank","authors":"Yoshihiro Kobayashi, A. Sorensen, T. Uryu","doi":"10.2534/JJASNAOE1968.2002.397","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2002.397","url":null,"abstract":"For storage and transport of liquefied gas such as LNG or LH2 (liquefied hydrogen), it is of great importance to reduce the boil off gas to a minimum. The thermal insulation system is playing a significant roll here. Though the specification of tank insulation should be decided by the boil off figure of a desired total system from a view point of an economical and practical use of it, the reduction of evaporated quantity is being demanded stronger, and any achievements to enhance the reduction are appreciated. The authors have introduced a new concept for enhancement of insulation efficiency by indirectly using the cold boil off gas as a protective shield or a heat sink to limit transmission of heat to the tank/cargo. To verify this theory of “vapor insulation system”, an experiment based on cold gas flow was carried out in a small scale apparatus to analyze carefully the effect on the heat transmission with and without cold vapor flow. These results were implemented in a calculation model of a spherical tank for LNG and LH2, and combined with some parameters such as gas flow quantity, gas temperature and location of gas passage. Based on this work realistic examples of design were proposed for a new insulation system. The configuration takes into account the concept of the small leak protection system for MOSS spherical tank. The principle of this new insulation concept proposed is that cold nitrogen gas which is produced by heat-exchange with the boil off LNG or LH2 vapor flows through a small passage created in the insulation structure. The upward flow of cold gas through the annular space around the tank will absorb the heat from the hold space of the cargo tank before it reaches the valuable liquid cargo, and it will simultaneously work as a leak detection system of cargo.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132760131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-01DOI: 10.2534/JJASNAOE1968.2002.55
Youngkyu Ahn, K. Kijima, Y. Furukawa
When a FPSO (Floating Production Storage and Offloading) is required to maintain the specified position during oil producing and offloading under the external forces such as ocean current, wind or wave, exact position measurement is firstly taken into consideration. GPS (Global Positioning System) is mainly used to measure ship's position. But the position measurements using GPS contain noise. This noise has large influence on DPS (Dynamic Positioning System), therefore it is necessary to remove the noise.In this paper, Inverse Linear Quadratic (ILQ) optimal servo theory using Kalman filter is applied to design control system of DPS. Generally, Kalman filter is to estimate the low-frequency motions of the vessel so that control can be applied to minimise the position error. But in this paper, Because we already consider motion of FPSO as low-frequency motion, Kalman filter is used to remove the measurement noise.The numerical simulations shows the performance of the combined Kalman filter and ILQ optimal servo system.
{"title":"On the Dynamic Positioning Control System of FPSO using Kalman Filtering Techniques","authors":"Youngkyu Ahn, K. Kijima, Y. Furukawa","doi":"10.2534/JJASNAOE1968.2002.55","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2002.55","url":null,"abstract":"When a FPSO (Floating Production Storage and Offloading) is required to maintain the specified position during oil producing and offloading under the external forces such as ocean current, wind or wave, exact position measurement is firstly taken into consideration. GPS (Global Positioning System) is mainly used to measure ship's position. But the position measurements using GPS contain noise. This noise has large influence on DPS (Dynamic Positioning System), therefore it is necessary to remove the noise.In this paper, Inverse Linear Quadratic (ILQ) optimal servo theory using Kalman filter is applied to design control system of DPS. Generally, Kalman filter is to estimate the low-frequency motions of the vessel so that control can be applied to minimise the position error. But in this paper, Because we already consider motion of FPSO as low-frequency motion, Kalman filter is used to remove the measurement noise.The numerical simulations shows the performance of the combined Kalman filter and ILQ optimal servo system.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128586588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-01DOI: 10.2534/JJASNAOE1968.2002.81
Chun-beom Hong, Y. Doi, Hidemi Mutsuda
Ship wave characteristics in a shallow and restricted waterway whose depth and breadth change in longitudinal direction are studied numerically.The Euler and continuity equations are employed for the present study. Boundary fitted and moving grid system is adopted in the numerical simulation. The convection term in the governing equations and the free surface boundary condition are solved by Cubic Interpolated Pseudo particle (CIP) algorithm in order to get high resolution of wave height in far field as well as near field.The present numerical scheme is applied to predict ship waves in shallow and restricted waterway whose depth and breadth vary in longitudinal direction.
{"title":"Numerical study on the effect of waterway shape on ship wave characteristics","authors":"Chun-beom Hong, Y. Doi, Hidemi Mutsuda","doi":"10.2534/JJASNAOE1968.2002.81","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2002.81","url":null,"abstract":"Ship wave characteristics in a shallow and restricted waterway whose depth and breadth change in longitudinal direction are studied numerically.The Euler and continuity equations are employed for the present study. Boundary fitted and moving grid system is adopted in the numerical simulation. The convection term in the governing equations and the free surface boundary condition are solved by Cubic Interpolated Pseudo particle (CIP) algorithm in order to get high resolution of wave height in far field as well as near field.The present numerical scheme is applied to predict ship waves in shallow and restricted waterway whose depth and breadth vary in longitudinal direction.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127672117","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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