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Article type: Cover
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Published: March 30, 1988
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Article type: Index
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Published: March 30, 1988
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Article type: Appendix
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Published: March 30, 1988
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Mitsuo KISHI, Katashi TAGUCHI, Keitaro NODA
Article type: Article
Pages
1-10
Published: March 30, 1988
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A modelling support system for system dynamics is designed by organizing the knowledge structures of generic patternized expectations and the rules on how to construct system dynamics models. The system is a production-rule-oriented consultation system written in PROLOG. The proposed system covers the system conceptualization and the model representation and the model representation. Brief executing processes of the proposed system are: i) Extracting concepts in a system by perceiving action/decision making and by inferring the causal relations. ii) Preparing a causal-loop diagram of the system by interconnecting the causal relations. iii) Transforming the causal-loop diagram into a flow-diagram. iv) Generating a simulation program. In order to facilitate the future modelling work, the proposed system has a knowledge base of facts acquired in systems modelling. A system dynamics model for maritime industries is presented using the proposed system, and structural issues involved in them are examined.
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Yoshiyuki INOUE, Keiko OKUZUMI, Sachiko ITATSU, Tetsuya HAYASHI, Noria ...
Article type: Article
Pages
11-25
Published: March 30, 1988
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In order to predict motion responses of a ship in rough seas, we usually need shipform data, loading condition and sea way condition. In the initial stage of ship design and while planning ship loading, for example, we do not yet have detailed data for predicting ship motion. For the sake of guidance for predicting motion responses, shipform characteristics, metacentric height etc. of general cargo ships, bulk carriers, pure car carriers and container ships are analyzed based on the data of many actual ships. In this paper, actual data and mean values of shipform characteristics are presented, and motion responses of standardized ships with various lengths in short crested irregular seas are analyzed by ordinary strip method. The results are also compared with the guidance of IACS for acceleration components.
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Yoshiho IKEDA, Naoya UMEDA, Noiro TANAKA
Article type: Article
Pages
27-34
Published: March 30, 1988
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The effects of forward speed on the roll damping of a high speed craft are experimentally investigated. The roll damping is assumed to be divided into five components, which are the wave, the eddy, the lift, the bilge keel and the fin components. In the present analysis the friction component is ignored because it is small enough for such a hard-chine vessel. Measured lift componet of the roll damping linearly increases with forward speed up to Fn=0.4, and over Fn=0.4 increases rapidly due to the increase or the trim by forward motion. The empirical methods to predict the wave and eddy components proposed by Ikeda et. al. for conventional cargo ships are slightly modified, and can predicted the effect of forward speed on the components. The results show that the non-linear eddy component is dominant at Fn=0 and that the linear lift component is dominant at high forward speed if the vessel has no appendage like bilge keels and fins. The effect of forward speed on the bilge keel component is not so significant for normal frequency region of roll resonance. The experimental results suggest that the linear lift forces acting on the bilge keels may be important. A set of fins with the same area as the bilge keels is found to be more effective than bilege keel at high speed region because of its high lift derivatives.
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Matao TAKAGI
Article type: Article
Pages
35-44
Published: March 30, 1988
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Succeeding to the first report, this paper deals with the mean water level in progressive waves with bichromatic elements in finite water depth by use of the theory of transient waves. The second order velocity potential contains a new term which corresponds to the depression of the mean water level and the uniform flow. They make the amount of the depression of the mean water level ("Set-Down") larger than the one predicted by the usual theory. Hence, in most cases, the local mean water level is "Set-down" everywhere. In a few cases, however, it is "Set-up" in the smaller amplitude of bichromatic group waves due to slowly varried water level. Therefore, the terminology "Set-down" for the local water level of group waves in the report of the Ocean Engineering Committee in 16th and 17th ITTC is not adequate, and the terminology "Group-induced long wave" should be used.
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Susumu HIRANO, Shinji YOSHIKAWA, Yoji HIMENO
Article type: Article
Pages
45-52
Published: March 30, 1988
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In order to design a high speed planing hull form on the basis of modern hydrodynamics, it is necessary to clarify the flow round the hull and the pressure distribution over the bottom hull. The present paper deals with measurements of the bottom pressure distribution on a V-shaped planing plate with the length 0.754m. The 3-components, lift, drag, and moment were also measured and compared with the integrated values of the pressure distribution, showing a good agreement. Flow visualizations using tuft and alminium-powder methods were carried out to obtain the flow direction over the bottom hull. Spray root/edge lines were observed.
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Shigeru NAITO, Keisuke FUJIMOTO, Kazuhiko KAGAWA
Article type: Article
Pages
53-59
Published: March 30, 1988
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The measured value of added resistance in regular head waves of a ship with blunt bow is larger than the calculated one. It is considered that added resistance on the blunt ship in short length waves is mainly due to reflection of an incident wave at the bow. In this paper, the reasons of the difference between calculations and measurements are discussed using following experimental and theoretical studies. The model used in this study is a simplified ship model with three different bow shapes. l) Measurements of diffraction forces in regular head waves when the model is restrained. 2) Measurements and analyses of unsteady wave pattern. 3) Numerical calculations are performed by using the Ray theory to consider the difference of the propagated characteristics of elementary waves near the hull surface of a ship between in the uniform flow field and in the distorted one deformed by the existence of the ship with blunt bow.
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Taketoshi OKUNO
Article type: Article
Pages
61-67
Published: March 30, 1988
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Recent development in fluid dynamic have generated and enlarged demand for experimental technique of velocity field measurements. The so-called PIV (Particle Imaging Velocimetry) enables to obtain velocity data of extended spatial region of the flow field simultaneously. This paper describes a method of image processing for obtaining the velocity distribution. Image data of the flow field obtained by flow visualization with tracer is transformed to spatial frequency domain by using two-dimensional Fourier Transform. The velocity vector is determined by dividing of two image data which are taken in a small time difference. Some of the application of 2D-FFT analysis are also shown here. Low-pass and high-pass filter are applied to tracer image data, the so-called speckle photography method is simulated by using computer, and the possibility of turbulence measurement with PIV is examined.
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Shoichi NAKAMURA, Norihisa KODAN, Shigeru NAITO
Article type: Article
Pages
69-76
Published: March 30, 1988
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It is important to study the wind forces-lift, overturning-moment and drag-acting on the deck of semi-submersible oil rig, because she usually is operated at rough sea. When we consider her role over the free surface, she is divied into three parts, deck, column and superstructure. For safe operation of her, it is expected to clarify the mutual interaction about the wind forces among them. The estimation method for the wind forces of the deck has not been established. Under the shelter of column and superstructure, the wind flow near the deck surface is very complicated. The experiments about the effect of column and superstructure on the wind forces acting on the deck have been carried out and the calculation to estimate them has been performed by using the simple flow model around the deck. In this paper, the results of them are presented.
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[in Japanese]
Article type: Article
Pages
77-80
Published: March 30, 1988
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[in Japanese]
Article type: Article
Pages
81-82
Published: March 30, 1988
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[in Japanese]
Article type: Article
Pages
83-85
Published: March 30, 1988
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[in Japanese]
Article type: Article
Pages
87-91
Published: March 30, 1988
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[in Japanese], [in Japanese]
Article type: Article
Pages
93-96
Published: March 30, 1988
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[in Japanese]
Article type: Article
Pages
97-98
Published: March 30, 1988
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Article type: Appendix
Pages
99-100
Published: March 30, 1988
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Article type: Appendix
Pages
101-108
Published: March 30, 1988
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Article type: Appendix
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Published: March 30, 1988
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Article type: Appendix
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Published: March 30, 1988
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Article type: Appendix
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Published: March 30, 1988
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Article type: Appendix
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Published: March 30, 1988
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Article type: Appendix
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Published: March 30, 1988
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Article type: Appendix
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Published: March 30, 1988
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Article type: Cover
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Published: March 30, 1988
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Article type: Cover
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Published: March 30, 1988
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