Transom stern form design is not easy even now. One reason is that the stern wave due to a transom stern contains complicated phenomena such as forward-oriented wave breaking just behind the stern end and therefore it is not easy to treat the stern wave resistance analytically. In this paper, at first, a transom stern form design method has been proposed as a practical application of results of our recent studies on the transom stern. Next, to obtain necessary data for the proposed method, a series of model tests have been conducted. Then, to demonstrate the effectiveness of the method, an example of transom stern form design by the method using the data has been shown.

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Adjoint variable method (AVM) is known as one of time saving sensitivity analysis method for hydrodynamic shape optimization technique based on CFD calculation and gradient based optimization algorism. But it is rare that the accuracy of the sensitivity coefficient calculated by AVM or its dependency on the computing scheme is evaluated. In this study the adjoint variable method is applied for sensitivity analysis of two dimensional viscous flow around a wing. The objective function is lift coefficient calculated from CFD analysis and design parameters are coordinates of Bezier curve's control point which form the profile of the wing. For estimating the accuracy and its dependency on the computing scheme or conditions, two kind of discretization scheme for flow computation are applied and three kind of computational grid are used. The calculated sensitivity coefficients by AVM on each condition are compared with ones which are calculated from finite differential approximation. And the influence of the convergence accuracy of adjoint equation to the calculated results of sensitivity coefficient is also evaluated.

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This paper describes the development of the shear stress sensor for full-scale ship experiment conducted in the SR239 project (1998-2001) of the Shipbuilding Research Association of Japan. In that project, the full-scale experiment had been planned since the first year. In this paper, the basic design of the sensor is discussed and.some results of preliminary experiments were shown. Based on those results, the seven sensors were used for full-scale experiment using a training ship "SEIUN MARU". The results of shear stress measurement with and without micrrobubbles are presented and discussed. At some place on the full scale ship surface, the large reduction of local skin friction is observed. The effect of the ship speed and the motion is discussed based on the results.

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For our sustainable development, it is required to reduce CO_2 emission also in the field of the shipping. There seems to be a possibility of reducing CO_2 emission by improving the navigation. The conventional weather routing system provides a minimum time route using the isochrone algorithm. However, from the environmental point of view, a new weather routing system aiming to reduce CO_2 emission must be provided. Therefore, in order to reduce CO_2 emission from ships, a new weather routing system for a novel sail assisted ship is developed. The new system has features that not only choose sea route, but also adjust ship speed. In the calculation of the new system, a bulk carrier of the transpacific route is selected as the novel sail assisted ship. Equilibrium equations of longitudinal force, lateral force, yaw moment and heel moment are solved to estimate ship speed in actual seas. From the numerical examinations, it becomes clear that the new system reduces 17.4% of CO_2 emission.

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We consider transient free surface flows near a contact point between a body and the free surface and discuss its treatment for numerical simulation of their interactions. The Boundary Element Method is employed and we investigate whether the simulation of unsteady free surface flow due to the abraptly starting motion of a body is practically possible or not. Numerical studies on body shapes with no curvature are carried out. Introducing the modeling of jet flow near the body, we can simulate free surface flows in a wide range of Froude numbers.

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As a simple way of validating computed results of wave-induced ship motions, asymptotic values for very long waves (very low frequencies) may be checked. It has been said that the nondimensional amplitudes of both heave and pitch approach 1.0 in head waves. However, especially in the pitch mode, it is not so obvious whether this is true and, if this is the case, which terms of hydrostatic and hydrodynamic forces are balanced. To make these questions clear and obtain an asymptotic expression of the complex amplitudes of heave and pitch for very long waves, theoretical study is made by means of the strip method. It is shown that the limiting values of nondimensional amplitudes of both heave and pitch must be really 1.0 in a very long head wave, which holds irrespective of the forward speed and geometry of a ship. It is also stressed that the pitch amplitude will diverge numerically for very long waves, unless hydrodynamic forces in the radiation and diffraction problems are consistently balanced. These results theoretically derived are confirmed by numerical computations, with a modified Wigley model used as an example.

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It is well known that calculated results of pressure by MPS method has an unnatural oscillation with high frequency. To reduce the oscillation, a numerical method is developed by introducing an auxiliary computation procedure subordinated to MPS method. There are two characteristic points in the proposed computation scheme. One is the source term of pressure Poisson's equation. The other is the ALE procedure in the velocity-pressure coupling scheme. The calculated pressure is improved by the present method.

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A very small one-man hydrofoil craft was developed and the motion and maneuverability of this boat were measured and compared with the numerical simulation. The boat is 5.8m long and weighs 172 kgf including one crew. The hydrofoil system is canard type consisted of fully submerged foils. The pitching motion is controlled automatically by a height control mechanism attached to the fore foil. On the other hand, for the rolling motion, the boat has no automatic control system. The crew maintains lateral stability by controlling rudder angle and shifting his weight in the cockpit just as controjling a bicycle. In order to clarify the stability mechanism of this craft, sea tests were performed to measure the motion of the boat, rudder angle and attitude of the crew. Then numerical simulation was performed considering the whole motion of the boat such as surge, sway, heave, roll, pitch and yaw. Simulated results agreed well with the measured data.

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Monitoring and recording of ship operating conditions at all times on board can help estimate the seakeeping performance and its reduction. We discuss a stochastic model for the analysis and long-term evaluation of monitoring data. The model is obtained by the analysis of wave height and ship responses measured on the actual ships, and expressed by the stochastic differential equation with three parameters. From a comparison of measured data, the validity of the model is indicated. Understanding parameters enables the evaluation and prediction of seakeeping performance. For examples, the long-term prediction and simulation of ship responses and the evaluation of ship operating condition are described.

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During the friction stir welding (FSW), the rotational distortion occurs according to operation conditions. When the rotational distortion grows large, FSW operation becomes impossible. A special binding fixture or coolant is effective ways to avoid the rotational distortion, but they are costly. We developed a new economical method to control the rotational distortion by heating both plate edges simultaneously with FSW The rotational distortion was calculated by numerical welding simulation and confirmed experimentally.

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During welding, deformation is produced as an unavoidable consequence. Inherent deformation method, in which the inherent deformation is introduced into the elastic FEM as the initial strain is one of the effective methods to predict welding deformation of large structures. When the weld length is long enough, inherent deformation is mainly governed by the heat input Q and the thickness of plate t. However, in assembling process of thin plates, the short weld with the length between 20〜200mm is often used especially to reduce distortion. In this case, inherent deformation is influenced not only by the heat input but also by the length of weld. In this research, an efficient measuring method to estimate inherent deformation of plate under bead welding using inverse analysis is developed. Based on this inverse analysis, the inherent deformation is estimated by measuring the three-dimensional coordinates at small number of selected points. Further, using the estimated inherent deformation, the welding deformation of a plate is predicted as the forward analysis. The distribution characteristic of the inherent deformation in short weld is also discussed in this paper.

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Welding technology is one of the main joining techniques and used in industry to assemble various products, such as ships, cars, trains and bridges. According to current trend in design, to achieve weight reduction, large structures are made of relatively thin steels with high strength. However, welding distortion in large thin-plate panel structure is usually cased by buckling due to the residual stress. Several mitigation methods, including preheating and thermal tensioning the plate during assembly, have been investigated and used by some fabricators. In this study, an elastic finite element method for predicting the welding distortion of three-dimensional thin-plate structures with considering welding sequence is proposed. In this method, the inherent strain is employed to model the local shrinkage due to welding itself, and the interface element is introduced to simulate the assembly process. The proposed method is applied to study the influence of welding sequence on the distortion of the large thin-plate panel structures during assembly.

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In this paper, the influence of the body surface on the water impact problem with the trapped air is discussed. It is assumed that the body surface and the water surface can be respecitively expressed by a elliptic paraboloid and a subsequence of circular hollows. Under this assumption, the impact force with the trapped air is investigated in the both cases that the dropped speed is constant and that it varies. Results show that the impact force becomes larger and larger as the steepness of the body surface increases when the elliptic paraboloid falls onto the distorted water surface, and that the effect of the trapped air on the impact force of the model scale is larger than that of the full scale. Result of the dropped speed shows that the trapped air influences the motion of the hull after it hits the surface of the water.

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This paper develops the hull form optimization method to determine a concept of a fast ship effectively and expeditiously based on the simulated annealing technique. The simulated annealing method is a kind of the emergent optimization methods, which has the advantage of describing the objective function and constrains easily. It therefore will be expected to be well suited to solve a design optimization problem involving a large number of design variables such as hull form deign of ships. The effectiveness of the simulated annealing method is ascertained in designing low resistance hull forms by using two examples of monohull and catamaran type of ships.

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Improvement of transportation systems in isolated-island routes is one of the most important factors in various island problems. To solve these problems, fast and convenient transportation systems between an island and a mainland are requested. Recently new types of ships like a fast passenger car ferry has been developed, and feasibility studies on such advanced ships are needed. A method for feasibility assessment of an advanced ship was proposed on the bases of a demand prediction method using a generalized cost model, or a sacrifice model, and an economical evaluation method using break-even analysis by the authors, and applied to some island routes in Japan. In the former paper, a feasibility of a fast passenger car ferries was assessed in the condition of competing it with other transportations, like airplanes and conventional car ferries. In the present study, a method to assess the feasibility of a fast passenger car ferry operated with conventional passenger car ferries by a company is developed, and applied to the Oki route, in Japan. The results demonstrate that the method can select an appropriate type among several types of the fast passenger car ferries and show an appropriate combination of fast and conventional car ferries in the route.

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The containerization of general cargo transportation has made an innovative contribution to the growth of international sea transportation. The development of cellular containership had broken through the barrier against to larger ship size and higher ship speed due to troublesome cargo handling, so that the size of containership has been becoming larger and larger continuously. specially, since the advent of Post-Panamax type, the tendency of scaling-up is becoming enormously rapid. The technological features and effects of large-sized containerships on the transportation energy performance are investigated here by the statistical analysis of various containerships' principal items. The analysis reveals that, though the scaling up of ship size is very effective for improving the transportation energy performance, the effectiveness is decreasing in the ship size region larger than Post-Panamax type mainly due to the limits of cargo loading performance and the inevitable deviation from the optimum ship design conditions.

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In order to clarify the oceans role in the overall geochemical cycle of CO_2, getting to know a vertical concentration of phytoplankton is very important. The authors measured the vertical distribution of chlorophyll a in the western pacific equatorial ocean during the R/V MIRAI cruse (MR01-K05, MR02-K06), and analyzed a number of data which measured on the ship. The results show that the phytoplankton distribution has strong correlation with mixed layer depth and compensation depth. Using the CTD and ADCP data, the estimated model for the change of chlorophyll distribution is constructed.

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In the previous paper, the authors applied the proposed MFT (Multiple Fourier Transform) method to the analyses of simulated sea surfaces composed of two different wave systems and radar echo signals from those sea surfaces. They showed that the MFT method can discriminate the directional and lengthwise characteristics of individual wave system that composes the confused sea surfaces, and that it can estimate the spreading characteristics of confused sea surfaces. They also show that the accuracy of analysis of MFT method is better compared with the results of 2-Dimensional Fourier Transform of PPI image. In the paper, they apply the MFT method to the analyses of radar echo obtained onboard ships of two different types sailing in a seaway. They show that the proposed method is able to discriminate directional and lengthwise characteristics of 2 different wave systems existing in actual seas.

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In Indonesia, since 1974 a new national energy policy was formulated and the development of coal production becomes one of the main thrusts of policy implementation. Recently, the annual domestic consumption increased from 0.2 million tons in 1983 to 29 million tons in 2002. The pusher barge system for coal transportation from Kalimantan coal mines to the Java power plants has already been studied, and results showed that this is the most economical form of transportation. In this paper, the authors investigated the economic and environmental feasibility of the pusher barge system from Sumatra coal mines to power plants in Java Island. For this purpose, the pusher barge system has been compared with several modes of transportation, from the economic and environmental points of view. For economic comparison, the required freight rate (RFR) has been chosen as criteria and the life cycle assessment (LCA) method has been selected for environmental comparison. It can be concluded that the pusher barge system has some advantages over other transportation modes for domestic coal transportation in Indonesia, from both the economic and environmental points of view.

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The purpose of this study is to establish an evaluation method of ride quality on board vehicles by using human facial expression as an objective physiological index. In the previous report, the authors have introduced the concept of the Fourier Descriptor (FD) into evaluation of facial expression, and they concluded that the FD method is useful for quantitatively expressing an enclosed facial factor such as an eye. This paper deals with the application of FD to the outline of eye and mouth and the analysis of the relation of these FDs to his/her mental situation. The subjects are asked to exhibit the six fundamental emotions defined in the field of psychology and the FDs were obtained from the shape of their eye and mouth. The discriminant analysis was applied to classify facial expressions into the six fundamental emotions and it was found that the optimised model with a comparatively small number of FDs could be discriminating with a high discrimination rate.

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The authors have been studying facial expression as a physiological index of motion sickness and ride quality. In this report, they observed and analysed facial expressions to extract some features when persons, exposed to a low-frequency oscillation, were suffering from motion sickness. As a result, a blank expression is found to be characteristic of the beginnings or a mild symptom of motion sickness. Experiments using line-drawing faces were conducted to clarify each contribution of facial factors such as eyebrows, eyes and mouth in the evaluation offacial expression. The lines on the face become an important key to suppose the condition of hypodermic facial muscles. The fuzzy-measure theory was introduced to describe non-additive synthesis in the evaluation by man. The authors concluded that realisation ofa blank expression is in need of its clues on all of eyebrows, eyes and mouth.

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