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- Hull Form Improvement Using Real-Coded Genetic Algorithm -
Jun Ando, Kuniharu Nakatake
Pages
000003
Published: 2003
Released on J-STAGE: May 15, 2004
CONFERENCE PROCEEDINGS
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In this paper, we try to reduce the wavemaking resistance of catamaran according to a hull form improvement procedure. In the procedure, a weight function including some design parameters is multiplied to the initial hull surface in order to represent an improved hull surface. Objective function is the wavemaking resistance coefficient that is obtained by dividing the wave-making resistance by the square of the ship length. Rankine source method is employed to evaluate the wavemaking resistance of catamaran. As the optimization method, we adopt the real-coded genetic algorithm using the Unimodal Normal Distribution Crossover (UNDX). In the present study, we select the Wigley hull as the initial hull form. Initial catamarans are assumed combining two Wigley hulls for two cases of transverse distance between each hull. Numerical calculations are conducted for two Froude numbers. Improved hull forms and the values of wavamaking resistance are shown in each case.
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Seung Jin Shin, Satoru Yamaguchi, Taichirou Shimoda, Akiji Shinkai
Pages
000017
Published: 2003
Released on J-STAGE: May 15, 2004
CONFERENCE PROCEEDINGS
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Recently, importance of estimating of ship's propulsion performance in basic design stage is increasing because of growing in size, speeding up and diversification of ship. Since small high-speed craft's type of ship and its performance are various, it cannot be said that data which used in designing of small high-speed craft is enough. Authors have carried out towing tank test in still water by 1/16 scale model of small high-speed craft "WAKASUGI" and observed wave collapse phenomenon near the bow to establish the new evaluation technique for design of small high-speed craft.
In this paper, the relation between wave collapse phenomenon consist of wave and spray near the bow and measured ship resistance are described. A digital still camera and digital video camera are used to observe the wave collapse phenomenon in the tank test. The resistance coefficient obtained by the tank test is compared with the resistance coefficient obtained from presumptive function.
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(Part2) Hydrological model Test for Flow-through Method in Pitching Condition
Takeshi Shinoda, Nobuyoshi Fukuchi, Jun Takeuchi, Koutaro Nishimura, O ...
Pages
000010
Published: 2003
Released on J-STAGE: May 15, 2004
CONFERENCE PROCEEDINGS
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Ocean environmental problems due to the contamination of marine life through ballast exchanges are reported from every part of the world today. The damage caused to marine ecology in a given area and the hazards of noxious plankton on public health are regarded as important especially. IMO recommendations for ballast water exchange are taken as effective steps to contain these problem under present conditions. However, the issues involved in ballast water exchanges are complicated due to several factors such as the size of tanks, the number of partition walls and the area and configuration of holes on them, the arrangement of bell mouth, the trim of the vessel, and so on. Because of these factors, there exist several ambiguities in the rate of actual ballast water exchange even when IMO recommendations are followed. The problems caused by ballast water exchanges was studied through hydrological experiments conducted using a numerical model based on actual ballast exchange methods in the first report. In case of some difference of density between an initial filled water and an exchangeing water, or case of some difference of pipe and manhole arrangement in the tank, an efficiency of ballast water exchange rate will change. In this paper as a continued report, hydrological model test on flow-through method is studied through an experiment by considering the pitching condition.
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KATSURO KIJIMA, YASUAKI NAKIRI
Pages
000009
Published: 2003
Released on J-STAGE: May 15, 2004
CONFERENCE PROCEEDINGS
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The authors have already proposed the practical prediction method for ship manoeuvrability in deep water by using the approximate formulae relating to the IMO Standards of Ship Manoeuvrability MSC137(76). In general, the manoeuvring characteristics of ship in shallow water may be quite different from that in deep water. It will be very important, therefore, to know the manoeuvring characteristics in shallow water as well as in deep water for safety of navigation. This paper proposes one example of the prediction method for ship manouevrability in shallow water. This prediction method based on simulation of ship manoeuvring motion by using the approximate formulae for hydrodynamic forces acting on ship as well as the former proposal for deep water. This paper also shows the useful method for prediction of ship manoeuvrability in shallow water at the design stage and for operation of ship in restricted water. By using this formula, it will be obtained to know the manoeuvring characteristics in shallow water with high accuracy. But as this approximate formula based on the data of model ship, it should be investigated to apply it to full scale ship in near future.
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Katsuya Maeda, Norio Hosotani, Kenkichi Tamura, Hirotomo Ando, Katsuhi ...
Pages
000014
Published: 2003
Released on J-STAGE: May 15, 2004
CONFERENCE PROCEEDINGS
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ince a reflective wave exists in a test basin, it is always necessary to take the influence into consideration in a model experiment.
However, if the boundary of basin can absorb a reflective wave completely even if it is a small basin, it will become possible to simulate of the infinite ocean space.
Based on this idea, National Maritime Research Institute completed the circular basin in April 2002.
It was a upper part of the deep-sea basin, the deep pit with 6m diameter was dug on the center of the circular basin.
128 sets of wave generators are arranged around this basin.
Each generator moves to make a wave, and compensates a reflective wave simultaneously.
It is possible to make various types of waves by combining a motion of wave generators.
In order to investigate wave making properties of circular basin, wave height distribution of regular wave, change of wave height and phase angle by time, and power spectrum and distribution function of irregular wave were measured and examination was added.
Consequently, in the model test in this basin, although it needed to be cautious of selection of the size of a model and a wave frequency, it has confirmed that long-sustained measurement was possible, without caring about a reflective wave.
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Kohei Matsuo, Akiji Shinkai
Pages
000016
Published: 2003
Released on J-STAGE: May 15, 2004
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Authors study about a new statistics showing the feature of sea wave climate, especially being for the purpose of designing ships or sea structures. Statistical theory called "Long-term prediction methods" is introduced to estimate occurring response of ships during its operation periods. For this theoretical technique, the feature of sea waves must be expressed by the joint probability between wave height and wave period, so that accuracy of estimation of ship responses from sea waves relies on the accuracy of wave statistics. Authors have intended to arrange a new database, which composed from the satellite wave data. Measurement from remote-sensing has unique haracteristics, because it measures periodically, accurately and homogeneously for almost all the sea surface. It would be expected that these data satisfy more reasonable to the theory of probability and statistics than that of others data. This would lead to realize more suitable designing of ships or marine structures.
This paper describes about 2 topics. The one is to study statistical
characteristics about Significant Wave Height data derived satellite measurement. It is evaluated by comparing some Buoys data supplied from JMA
(Japan Meteorological Agency), and a degree of fitting to a distribution
function is checked by using of confidence-limits about estimated population. And another is about a study of some mathematical models concerned with Wave Period. Stochastic model about probability distribution of Wave Period and regression model about statistics of Wave Period is verified by analysis of Buoys data. In these verifications about Wave Height and Period, it is concluded that Wave Height data has enough accuracy and tendency of specific distribution pattern. And also be concluded that some supposed models about Wave Periods are tend to has a distribution of Logarithm-normal, and regression model express its tendency a certain grade.
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Shiro Kataoka, Akira Sueyoshi, Kiyoshi Arihama, Hidetsugu Iwashita, Mi ...
Pages
000015
Published: 2003
Released on J-STAGE: May 15, 2004
CONFERENCE PROCEEDINGS
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The non-linear unsteady pressure acting on the hull surface of the ship advancing in waves is numerically investigated by using a time-domain computation method.
In this study, A Green function method which satisfying the linearized free-surface condition is adopted as the time-domain computation method and is applied to so-called the body non-linear problem which can capture the change of hull form below the calm water due to the ship motion.
Computations are carried out for the modified Wigley models which have different flare shapes at bow and stern. The unsteady pressure distributions on the hull surface are also simulated.
Through the comparisons with the results of Rankine Panel Method which satisfying the linearized free-surface condition, it is shown that the non-linear effects on the unsteady pressure are remarkably observed at the bow near the resonance point
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Hironori Yasukawa, Kuniji Kose
Pages
000002
Published: 2003
Released on J-STAGE: May 15, 2004
CONFERENCE PROCEEDINGS
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A practical simulation method is presented for predicting the various ship maneuvering motions such as stopping maneuver, accelerating turn, large drift motion at low speed and so on. This method is applied to the maneuvering booklet according to IMO Resolution A.601 for Pure Car Carrier(PCC) with 180m in ship length. The booklet includes normal maneuvering characteristics in deep water, stopping and speed control characteristics and maneuvering characteristics in wind. It is demonstrated that the present method is useful for providing the maneuvering booklet as a design tool.
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Jun Takao, Taketoshi Mori, Nobuyoshi Fukuchi, Takeshi Shinoda
Pages
000018
Published: 2003
Released on J-STAGE: May 15, 2004
CONFERENCE PROCEEDINGS
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In the fire safety design for a ship, the engine room fire due to flammable oil is a very important issue and has received much attention in recent years. However, the nature of the engine room fire is still not well understood due to its extreme complexity of the physical and chemical mechanisms. A series researches have been carried out by the authors to investigate the engine room fire, and the emphasis of the present study is placed on the emission and the movement of the smoke during oil burning, which is very important phenomenon for a successful fire safe design such as setting up escape routes and installing fire detectors.
In the present paper, the experiment of smoke movement and diffusion in an engine room model with smoke-producing agent is carried out for the fire safety design on fire detection, fire fighting and evacuation. Moreover, a three-dimentsonal numerical analysis using k-e based CFD model is performed to investigate the situation of smoke diffusion in engine room model. Then, from the characteristic of smoke obtained by experiment, the validity of numerical analysis is shown herein. Both experimental and numerical results clarified to be useful in designing more effective evacuation systems and more reasonable arrangements of smoke sensors.
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Akira Katoh, Takahiro Ohta, Youichiroh Hara
Pages
000001
Published: 2003
Released on J-STAGE: May 15, 2004
CONFERENCE PROCEEDINGS
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The authors described in the previous paper on the separation method of structural damping from hydrodynamic damping contained in ocean as a ship hull enviromentt and showed theoretically the structural damping expressed as a logarithmic decrement to be proportional to the nodal number of hull girder vibration. In addition,using the concept of resistance proportional to liquid velocity introduced by Rayleigh,the added mass was related to the hydrodynamic damping and its velocity resistance factor by Rayleigh was confirmed quntitatively by the experiments. The present paper confirmed the results in the previous paper by using the beam free at both ends instead of canti-lever beam at previous. On the other hand,for the hull girder vibration of bulk carriers, it waws reported in the papers that the movement and jumping in the natural frequencies were induced in the hull girder vibration. Such a resonance of hull and double bottom vibration is mainly due to coupling effect of added mass but effectiveless in structural coupling between them. In this point of view,the calculation methods of added masses were also studied for the case of coupling vibration of hull girder and double bottom structures.
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Osamu Baba, Yasuhisa Okumoto, Katsumi Kondo, Ryujirou Kusaka
Pages
000011
Published: 2003
Released on J-STAGE: May 15, 2004
CONFERENCE PROCEEDINGS
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Recently, the improvement in productivity has been rapid in the shipbuilding industry, and the automation and mechanization of factory processes have been carried out at Ishikawajima-Harima Heavy Industries Co., Ltd.(IHI). One of them is the "unit-panel" process, which is a modularized process for flat hull blocks. The unit panel is composed of one flat skin plate and the several longitudinals which are fillet-welded on the skin plate. This is mass-produced on the conveyor line efficiently. In the production of this unit, automatic CO
2 arc welders of high-speed, set up in tandem, have been developed to fillet-weld a maximum of five longitudinals simultaneously. During it's introduction, welding defects such as pits and blow holes occurred frequently in the deposited metal. Since it was understood that these defects were caused by the primer coating on the surface of the web plate there to prevent rust, a device to brush the surface shortly after the primer coating was applied, was devised, and the experiments using this equipment were repeated. As a result, the welding defects were made under the allowable level. This report outlines these tests and solutions.
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(Part3) Evaluation of improvement of operator's task loads
Mikio Koga, Nobuyishi Fukuchi
Pages
000004
Published: 2003
Released on J-STAGE: May 15, 2004
CONFERENCE PROCEEDINGS
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Recently in the running cost saving pursuit, the further reduction of crew members on board and the improvement of transportation efficiency by means of precise cargo planning for crude oil, products and chemical tankers tend to be inevitable. On the other hand, the incidents such as cargo oil leakage and contamination should be strictly avoided in order to prevent rightfully the environmental pollution and the deterioration of the quality of the products. In our previous papers, we presented the specific developmental experiences and the methodology of ensuring safety and reliability of the automatic system for safe cargo handling, and evaluated the quantitative degree of the improvement of safety along with the relationships between the conventional site operation, the centralized remote operation and the full automatic control.
In this paper, the objective and subjective methods in which find out the amount of task loads eliminated by means of the full automatic control system are proposed. Moreover, the evaluated quantitative degrees of the improved task loads through the hearings for the skilled onboard cargo operators are also presented. The quantitative evaluation of the improvement for task loads are also analyzed onto the conventional site operation, the centralized remote operation and the full automatic system respectively and compared the effectiveness each other.
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