日本船舶海洋工学会論文集
Online ISSN : 1881-1760
Print ISSN : 1880-3717
ISSN-L : 1880-3717
3 巻
選択された号の論文の36件中1~36を表示しています
論文
  • 及川 正道, 経塚 雄策
    2006 年 3 巻 p. 1-12
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    An ocean model using "cut-cell method" has been developed to simulate the flow field around three-dimensional complicated topography via the modification of the MEC model, an ordinary Cartesian coordinate model. In the developed model, the finite volume method is employed for the accuracy of mass- and momentum-conservations. As an application, the developed model is applied for the analysis of the tidal flow of a bay connected with the ocean by a very narrow and oblique channel. Although results by the original MEC model strongly depend on the direction of the channel, the results by the developed model show good agreement with theoretical values. Then, the developed model is applied for the analysis of the flow around a tall seamount in steady background currents. Those results are discussed in comparison with the results by the original MEC model.
  • -被衝突平板寸法の影響の検討-
    肥後 靖, 山田 良
    2006 年 3 巻 p. 13-18
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    The impact force due to waves acts on the marine structures and sometimes gives a serious damage to the structures. The monitoring system for the wave impact forces will be required to achieve the structural safety.When the wave impact force acts on the structures, the sound generates at the same time. If there is any correlation between the impact force and sound pressure, it is considered that the measurement of sound may be used as the monitoring system of the wave impact forces. In this paper, we present the experimental results to make clear the correlation between impact pressure and generated sound when dropping water hits the flat plate as the first stage.
  • 劉 平健, 小林 英一, 堀端 大雅
    2006 年 3 巻 p. 19-26
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    This paper discusses the evaluation of modal shift from truck and car transportation to sea transportation by use of the ecological footprint method. Three representative transportation routes were selected for analysis; those are routes between Osaka and Shin-Moji, routes between Sapporo and Osaka and routes between Tokyo and Tomakomai. The use of modal shift covers wide environmental impacts, including the use of fossil fuel energy, global-warming and sea or land resources. We calculated the carbon dioxide emission and the forest request for these changes before and after using modal shift in this study. The aim of this paper is to show an ecological footprint calculation related to the modal shift in transportation. Based on ecological footprint assessments, this article confirms that there is substantial potential for reducing the ecological footprint by using modal shift.
  • 奥田 成幸, 新井 康夫, 河口 信義
    2006 年 3 巻 p. 27-33
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    Multi-path signal affects to decrease the quality of receiving signal according to a bad influence on direct receiving signal for data communication. So developers of GPS receiver, antenna and software have been making their efforts to remove multi-path signal. For the ship, in the case of measuring draught, the draught gauge is developed using ultrasonic wave as remote display equipment for large vessels, but in general they read out from draught marks. These measurements are taken at mooring or anchoring, so it is impossible to measure on sailing. We considered constructing the measurement system of draught by utilizing multi-path signal effectively. The proposal system is able to get wave height analytically from GPS signal. Such as draught measure on board, it is possible to remove the personal error of measurements because of mechanical and automatically measurements by this system against measuring items by eyes. In this paper, firstly the proposed Draught Measurement System is explained. Secondary, a simulation for availability of this system is shown, and especially our simulation show that a narrow beam width makes measurements more precise. Finally, an experiment that was used the prototype system was described to verify this proposed system. From the results of the simulation and the experiment, several problems to be solved are made clear, and it is considered that the proposed system had a possibility to use one of the draught measures.
  • 乾 正幸, 佐藤 徹
    2006 年 3 巻 p. 35-46
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    A new concept for CO2 geological sequestration is proposed as one of promising countermeasures against the global warming. For general geological sequestration technologies, there are still some issues we need to tackle, such as the shortage of possible sites to sequestrate, environmental risks due to leakage, and costs. In order to solve these problems, we propose a system to sequestrate a large amount of CO2 in the form of gas hydrate under the seafloor safely. In this system, we capture a mixture of CO2 and N2 from the flue gas exhausted from a coal-fired power plant and inject the mixture into marine sediments, where pressure is high enough and temperature is low enough to form hydrates. Besides, by using the CO2 + N2 mixture gas, we can reduce the cost and avoid the blockage by the hydrates in marine sediments. In this work, we assessed the potential amount of sequestrated CO2 and the cost of this system. From the results, the amount of CO2 that can be sequestrated offshore Japan by this system was estimated to be twice and the sequestration cost was reduced by 15%, compared with those of CO2 aquifer storage.
  • 経塚 雄策, 郡司 智博, 若濱 久敬
    2006 年 3 巻 p. 47-52
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    There are several kinds of energy resources in the ocean but the utilization of the ocean energy is far behind the other natural energies such as solar and wind. A feasibility study on the tidal current power generation by making use of a bridge pier in the narrow strait is introduced in this report. There are several advantages to making use of a bridge pier for the tidal power generation. Current velocity increases near the pier, therefore the tidal power generation becomes more efficient because the power is proportional to the cubic of the current velocity. Furthermore, the pier is convenient for the maintenance of the hydraulic turbine and the power unit. The project is now underway at the Ikitsuki Bridge in Tatsuno-Seto Strait of Nagasaki Prefecture, where the tidal current was measured by the bottom mount ADCP for one month. The numerical simulations of the tidal current were conducted by the MEC Ocean Model, and the results were compared with the measurements. A long term estimation of the tidal current power is presented and the variation of the power by the lunar period is discussed. Lastly, the in-situ measurement results of the waves are presented.
  • 有馬 英利, 長谷川 堅一, Lahar BALIWANGI, 古荘 雅生, 石田 憲治
    2006 年 3 巻 p. 53-59
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    This research was build the model after marine hazard and simulate from the viewpoint of making damage by the marine hazard small not from the viewpoint of preventing a marine hazard. Elements of the model were quantified to easy to compare and examine the simulation result. Human factors, one of the elements of the model, is difficult to quantifying. So human factors was made into random number. To simulate the model which has indefinite elements used application software based on system dynamics. This research focused on after the marine hazard, the model made the risks of which extent occurs because of the change in the situation. We tried to examine the causal relation between the human factors and the occurring event risk which based on the model.
  • 辻本 勝, 南 佳成, 村山 貴彦, 高井 博司
    2006 年 3 巻 p. 61-68
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    We propose a new navigation system for coastal shipping to decrease fuel consumption and CO2 emission. The navigation system, called WAN-CS, optimizes engine revolutions with constraint of the voyage schedule. For coastal shipping precise forecast system is expected because time of the voyage is short and geographical features of the route must be considered. Thus a new weather forecast system was also developed. The system forecasts four times a day though conventional system provides two times a day. The interval of spatial grid is selected in 2 minutes and the time interval is selected in 1 hour. Ship responses were estimated by solving equilibrium equations of longitudinal force, lateral force and yaw moment considering the engine characteristics. In this paper for reducing fuel consumption a simulation of a coastal cement carrier, which navigated the Ube-Nagoya route using WAN-CS was carried out. It is found that the fuel reduction by WAN-CS achieved 33% from the result of the simulation.
  • 有木 俊博, 鈴木 克幸
    2006 年 3 巻 p. 69-76
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    To optimize sea transportation system between Japan and China, this paper proposes a new method. In this method, two stages of optimization are required. At first stage, the route of each ship is fixed, and amount of freight that each ship transports, is optimized using linear programming. At second stage, the route of each ship is optimized with the indicator of the first stage, using genetic local search that introduces local search in genetic algorithm. Since, the second stage is the combinatorial optimization, computational cost becomes huge, and this paper proposes Adaptive-GLS method for efficient combinatorial optimization. By this two stage optimization, the logistic transportation system is optimized.
  • -オーダー式配船への取り組み-
    松倉 洋史, 勝原 光治郎, 大和 裕幸
    2006 年 3 巻 p. 77-85
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    Tramper allocation is important and difficult work operation because it affects heavily on transport efficiency and stability although a lot of factors must be considered carefully and properly. Provided that high performance tramper allocation plan be generated automatically by using computer program, it is very useful not only for labor saving but also for designing highly efficient enterprise-level maritime transport system through various and repeated analysis. There are 2 major types of tramper allocation ways. One is "tank balance type (or VMI: Vender Managed Inventory type)" and authors took it up in the former paper. In this paper we tried to solve the other one, "order type" tramper allocation. In "order type" allocation an operator receives a lot of orders from cargo owner in which detailed tasks are described, for example loading port name, day, item, quantity, and the operator tried to execute all the orders completely and efficiently under the restrictions. Firstly, we developed "order-type" allocation method by utilizing GA: Genetic Algorithm and logistics simulator, and implement it into an automatic allocation system. Secondly we apply it for a transport system modeled with a real ship operator and assess the system performance. We could conclude that our automatic tramper allocation system could generate fine allocation plans those are as efficient in total fuel consumption as the one made by human operators with high probability.
  • 尾崎 雅彦, 南浦 純一, 太田 真, 佐々木 裕一, 松浦 正己
    2006 年 3 巻 p. 87-95
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    Ocean storage of the captured CO2 from fossil-fuel burning is a possible option for mitigating the increase of CO2 concentration in the atmosphere. Moving-ship type of CO2 ocean storage is a concept whereby captured and liquefied CO2 is delivered by ship to a site and injected into the deep ocean by means of a pipe suspended beneath a ship as it slowly moves through the water. In case of bad weather conditions, CO2 marine transport and operation on the sea should be adjourned although CO2 would be captured at the plant every day. It is, therefore, required that the system would have the buffer storage at the port and the extra shipping ability to recover the delay of schedule. Since the large scale of such spare capability might lead to the increase in cost, it is needed to investigate how to plan the system allowed for weather conditions reasonably. In this study, a time series model of sea state through one year is generated for a hypothetical ocean storage site, based on the wind data observed with satellite remote sensing, and simulations of CO2 marine transport and operation on the sea are carried out considering the operational limit of sea state. In this approach, the continuing bad weather days or the frequent occurences of rough sea condition during the specific season are counted automatically. In order to pursue higher efficiency of the operation, side-by-side type and tandem type of moorings are applied for the simulations and compared. Finally, cost assessments under the several assumptions are carried out to see the relative merits among that number os ships would be increased, that the loading capacity of a ship would be increased, and that the storage capacity at the port would grow, which are generally in trade-off relationships.
  • 秋元 博路, 久保 昇三, 川上 真秀 , 田中 幹樹
    2006 年 3 巻 p. 97-103
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    A new concept of Wing In Surface Effect Ship (WISES) is tested by self-propulsion models. The concept is a canard type WISES with forward-mounted aerodynamic propellers. It is expected to show good performance for the take off on waves. The present authors have built a 3.6m length model to demonstrate the concept. This paper describes the concept, the structure of the model, test results and discussions about the real sized ship, and finally concluding remarks.
  • 福地 信義, 田中 太氏, 古賀 幹生, 村田 理
    2006 年 3 巻 p. 105-117
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    The thinking faculty and operating ability of cargo operators tend to be affected by their mental task loads under the pressure from liquid cargo loading/unloading environment. The suitable cargo handling support system has to be taken to cope with the relation between tensional stress degrees and human errors of operators during cargo handling.This paper, on the subject of mental stress and task loads of a liquid cargo control operator, consists of the quantitative analysis of the tensional stresses by measuring the fractal nature of heart rate variability under mental work-load during cargo handling on two domestic oil tankers that are respectively equipped with/without the automatic cargo control system. And the way of supporting cargo handling in order to reduce the work-load and human errors is predicted for the task with high-tension under complicated condition of cargo handling.Furthermore, the specific method to search for almost all of the human error factors, that could be taken measures by the automatic handling system, is proposed. And the evaluation method of the quantitative degree of the improved safety on the basis of probability of human error in the functional system is carried out using apprehensive degree that is defined as similar to the sense scale based on the experience of skilled ship cargo operators. The quantitative evaluation for the improvement of safety is predicted respectively to the conventional site operation, the simple remote operation with monitoring and the operation by full automatic system for comparison.
  • 宋 玉中, 椎原 裕美, 松下 久雄, 中井 達郎, 永山 友哉
    2006 年 3 巻 p. 119-124
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    A disaster happened in the nuclear power plant in Japan in August 2004, which was caused by failure of the condensation water pipe in the secondary line. The possibility of occurrence of such a disaster in ships has concerned the shipping industry due to the constructive similarity between steam, feed water, condensation piping for main or auxiliary boilers in ships and that in nuclear power plants. Nippon Kaiji Kyokai has therefore investigated and gathered data on corrosion in piping lines in ships in collaboration with major Japanese shipowners right after the disaster. The results of the investigation shows that similar corrosion failure as in the nuclear power plant has occurred in steam/feed water/condensation water pipes for main and auxiliary boiler plants in ships without causing severe consequences. And it is also found that this kind of failure, named "Flow Accelerated Corrosion" and referred to as "FAC", is caused by erosion-corrosion at a place where the flow is extremely turbulent, such as a location right downstream side of a orifice or a control valve, or at bend parts including elbows, etc. under strong influence of temperature, flow velocity and pH of the fluid, etc. The results of actual pipe wall thickness measurement of steam, condensation water and feed water pipe lines at bend parts, at T-junctions, behind orifices, behind valves and at diffusers/reducers with a ultrasonic thickness gauge shows the very definite evidence of a reduction in wall thickness of carbon steel piping. It was confirmed that the amount of actual reduction in wall thickness could be well predicted by Kastner Equation. Based on the consideration of fracture mechanism, safety assessment of corroded areas was conducted and it has been concluded that a hole is possibly generated in corroded areas in advance before rupture of pipes and the corrosion hole is unlikely to propagate unstably. The result shows that piping systems in ships might be considered to be safe from a view point of LBB, which means Leak Before Break, because the failure will be able to be detected by water leakage into lagging of pipes.
  • 安川 宏紀, 平田 法隆, 小瀬 邦治
    2006 年 3 巻 p. 125-131
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    This paper describes the improvement of course-keeping ability of a ship by attaching the skegs. The ship was designed as a high speed monohull with 40 knots by water jet propulsion system, however, the remarkable course-keeping instability appeared unfortunately. To improve the course-keeping ability, the skegs with As/(LT)=1/50, where As is the total skeg area, L the ship length and T the draft were designed. The captive model tests such as the resistance test and circular motion test were carried out to capture the hydrodynamic force characteristics for the ship with and without skegs. Based on the experimental data, maneuvering simulations such as 15/15 zig-zag maneuver and 30deg turning were made to investigate the effectiveness of the skegs. Through the simulations, we found that skegs with As/(LT)=1/33 are needed for improving the course-keeping ability of the ship. It was confirmed that the skegs are effective in the wide speed range from slow to high near 40 knots by oblique towing test for various ship speed.
  • 安川 宏紀, ファイズル アムリ アドナン
    2006 年 3 巻 p. 133-138
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    Lateral drift occurs due to the effects of wind forces and/or wave drifting forces in ships sailing in actual seas. It is important therefore to investigate the influence of lateral drift on seakeeping performance to attain a rational design for ships. This paper describes the experimental results with respect to ship motions in regular waves and steady drifting forces for an obliquely moving ship. The experiments were carried out for SR108, container ship at seakeeping and maneuvering basin, Nagasaki R & D Center, MHI. Due to the effect of the hull drift, the lateral motions such as sway, roll and yaw are induced even in pure heading waves, which never appear in case without hull drift. Their amplitudes become larger with increase of absolute value of the drift angle. In beam waves, also, amplitudes of sway, roll and yaw become larger with increase of the drift angle. On the other hands, the influence of the hull drift on the motions of surge, heave and pitch is not remarkable. The influence of the hull drift on wave drifting lateral force and yawing moment is considerable large. The lateral drifting force acts on the hull so as to damp the lateral motion. The influence of the hull drift on the added resistance is small.
  • 李 聖旭, 貴島 勝郎, 古川 芳孝
    2006 年 3 巻 p. 139-145
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    Present study applies a three-dimensional vortex method to estimate the flow field around a container ship in oblique motion. The three-dimensional vortex method which does not need the grid generaion as a pre-process is a Lagrangian method. The governing equations of the three-dimensional vortex method are vorticity transport equations and continuity equations. In order to solve the convection and diffusion term of vorticity transport equations, present study uses the operator-split algorithm proposed by Chorin. A discreted vorticity model used in present study is vortex blob which is a sphere type and has Gaussian distribution of vorticity. Core-spreading method which calculates the diffusion of vorticity by changing the radius of vortex blob is used and 2nd order Adams-Bashforth method which calculates the convection of vorticity is used. Three-dimensional Hess and Smith type panel method is used to estimate the initial flow field. In present study, flow fields around a container ship in oblique motion (β=3°, 6°, 12°) are shown as results of calculation and usefulness of three-dimensional vortex method is investigated.
  • -その2 風浪下での抵抗増加特性及び運航航路最適化-
    藤原 敏文, 上野 道雄, 池田 良穂
    2006 年 3 巻 p. 147-155
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    The steady-state cruising performance of a large passenger ship and a PCC under heavy wind and waves are presented in this paper. These kinds of ships have specifications with very large hull and superstructures above sea level. Strong wind causes large drift, heel and rudder angles to ships and exerts great influence on the ships' cruising performance. From safety and economical aspects the assessment of added resistance under such wind and wave loadings is very important for those ships. Formulation of the steady-state equations is based on the MMG model for a ship manoeuvring simulation to obtain the steady ship condition. The wind and wave loads on the ships are calculated using the latest methods proposed by the authors. From this analysis, the special specifications of the steady condition for the large passenger ship and the PCC are clearly understood. Moreover, speed loss and DHP increase of those ships in the sea around Japan are revealed in this paper. It is cleared in the calculated results that wind effect has a very important role for the ships with large superstructures. Finally using the results of steady-state cruising performances, the optimum ship routing in wind and waves is presented by the dynamic programming method in order to find the route for reducing the navigating time of the ships.
  • 青木 伊知郎, 貴島 勝郎, 古川 芳孝, 名切 恭昭
    2006 年 3 巻 p. 157-165
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    Since International Maritime Organization (IMO) has adopted "The Standards of Ship Maneuverability" as IMO Resolution MSC.137(76), the ship maneuverability is evaluated under this standard. Therefore, we have to know the accurate ship maneuvering characteristics at the design stage, especially the initial design stage. On the prediction method of ship maneuverability, there are many papers for estimating method of the maneuverability of a ship based on the model test, but there are few papers for predicting the maneuverability of a full-scale ship practically. The authors have already proposed the simple, accurate and practical prediction method for the ship maneuverability of model ship. So, we need to develop the practical prediction method for ship maneuverability of a full-scale ship in the deep water. In this paper, we propose the approximate formula of the interaction coefficient, γ and ωR0, obtained by comparing the predicted maneuvering motion with the measured results of the sea trial for twelve full-scale ships. We confirm the effectiveness of the practical prediction method using the approximate formula of the interaction coefficient for ship maneuverability of a full-scale ship. Though this approach must be validated in many kinds of ship as the next step, it will be expected that this method is very useful for predicting ship maneuvering characteristics at design stage on conventional ship.
  • -斜波中におけるユニットの上下運動と連結力-
    斉藤 公男, Bubi S. Prasodjo, 肥後 靖, 信川 壽, 前田 克哉, 松田 秋彦, 内田 満則
    2006 年 3 巻 p. 167-175
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    This paper discusses the elastic responses of a Coastal Cargo Ship (CCS) consisting of unit modules with advance forward speed in oblique waves. We introduce a simple way of connecting the units but with enough capability to link the modular part of ship as a unity. The flexible connection consists of male and female rubber fenders and additional pre-tensioned ropes. This kind of connection system is proposed to be used at inner sea with relatively calm waters wherein the modular ship can move at a moderate speed. The modules are assumed to be rigid compared to the connections. The computations are performed to investigate the vertical elastic responses of four-modules connected end-to-end by assuming that in the simple hinge, flexible rubber connections between adjacent modules, no gaps are found. A simple method is presented to study the hydroelasticity and rope tension forces of the modular ship with forward speed in oblique waves. The experiments for a three-dimensional model at Fn=0.16 in oblique waves have been performed to evaluate the effectiveness of the calculation method. In the experiments, deflections of each part were measured using calibrated potentiometers. Force transducers were used to measure the rope connection force between the modules.
  • -心理的反応の計測と解析-
    有馬 正和, 田村 裕貴
    2006 年 3 巻 p. 177-181
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    The purpose of this study is to establish a method for evaluating ride comfort of high-speed passenger crafts. The authors have conducted experiment on board a high-speed catamaran running across the Bay of Osaka, Japan. Measuring items were ship motion, and subjects' electrocardiogram and facial expression as human physiological responses to an oscillatory environment. Subjects' psychological response was also investigated by means of a questionnaire at 5-minute intervals during the voyage. The previous report demonstrates that lateral motion is necessary to estimate ride quality of a high-speed passenger craft. And the proposed 'ride comfort index' RCI was found to be a useful index for the evaluation of ride comfort. The present paper deals with psychological response in a ship environment. Mental-state affecting to the evaluation of ride comfort indirectly were investigated by a keyword-extraction method. Statistical analysis methods were applied to clarify the relationship between subjective psychological response and ride comfort of a craft. To conclude, the psychological measurements proposed here is effective to extract several factors affecting the evaluation of ride comfort.
  • 土橋 純也
    2006 年 3 巻 p. 183-188
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    In this paper, the influence of the body surface and trapped air on the water impact problem is discussed. It is assumed that the water surface can be expressed by a subsequence of circular hollows, and that the body surface can do the triangular prism, or circular cylinder. Under this assumption, the influence of the body surface and trapped air for the water impact problem is investigated in the case that the dropped speed is constant. Results show that the maximum value of the trapped air pressure becomes larger and larger and the period of that is shorter and shorter, as the steepness of the body surface increases, and that the impact force could be large because of the trapped air, even if the steepness of the body surface increases. Also, we find that the impact force becomes smaller and smaller as the steepness of the water surface increases, whether the air trapping happens or not.
  • -実数値遺伝的アルゴリズムを用いた多目的船型最適化-
    平山 明仁, 安東 潤
    2006 年 3 巻 p. 189-195
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    Practical ships have different operating speed, draft and trim for every load conditions. Therefore, in the case of hull form improvement, it is necessary to develop a different hull form for every condition, from a viewpoint of hydrodynamics. The present paper proposes a hull optimization method for reducing wave-making resistance using the real-coded genetic algorithms in multiple load conditions. The real-coded genetic algorithm of the optimization method, employs UNDX (Unimodal Normal Distribution Crossover) as a crossover operator, and employs POSS (Pareto Optimal Selection Strategy) as a generation-alternation model. The hull optimization for Series60 (CB=0.6) is carried out using the program which is based on the present method. In the optimization, many Preto solutions are obtained. These hull forms have low wave-making resistance by the panel-shift type Rankine source method on the full load condition and ballast condition comparing with the original hull form.
  • -水槽実験と3次元流体力解析理論の定式化-
    居駒 知樹, 増田 光一, 林 昌奎, 前田 久明
    2006 年 3 巻 p. 197-204
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    This paper describes the motion response reduction of floating structures by applying the aircushion supported system. Effects of the reduction are confirmed with model experiments in a wave tank. The two model types with aircushions are used to the experiments. One is mono-aircushion model and another one is tri-aircushion model. The response reduction can be confirmed from experimental results using both the models. We show the formulation for predicting hydrodynamic forces on aircushion type floating structures with three-dimensional effects, which are draft effect and so on. The validity of the theory and numerical calculation methods is confirmed.
  • (第一報:自己組織化マップを用いた運動制御システムの提案)
    西田 周平, 石井 和男, 古川 徹生
    2006 年 3 巻 p. 205-213
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    Autonomous Underwater Vehicles (AUVs) are attractive tools for maintenance of underwater structures and oceanography, however, there are a lot of problems to be solved such as motion control, acquisition of sensor data, decision-making, navigation without collision, self-localization and so on. In order to realize useful and practical robots, underwater vehicles should take their action by judging the changing condition from their own sensors and actuators, and are desirable to make their behavior, to adapt to the working environment. We have been investigated the application of brain-inspired technologies such as Neural Networks (NNs), Self-Organizing Map (SOM), etc, into AUVs. The motion of AUV is represented by complicated non-linear dynamics in six degrees of freedom with added-mass and hydrodynamic forces, and control systems should be adaptive and robust. In our previous adaptive control method using NNs, a time series of state variables and control signals should be fed into the control system in order to adapt the change of dynamic property and environment, therefore, the obtained information in the previous adaptation is getting less gradually. If the environment of the robot is rapidly changed, the previous control system takes time to adapt new environment and former environmental information does not remain correctly. Therefore, a new method, which keeps the information of initial state or previous environment and adapts to new environment, should be developed to improve the efficiency of the learning and reduce the learning cost with the use of the former environmental information which the robot had already learned. A new self-organizing decision making system for AUVs using modular network Self-Organizing Map (mnSOM) proposed by Tokunaga et. al. is discussed in this paper. The proposed decision making system is developed using recurrent NN type mnSOM. The efficiency of the system is investigated through the simulations.
  • -不安定現象の発生メカニズムと推定法-
    片山 徹, 藤本 将史, 池田 良穂
    2006 年 3 巻 p. 215-223
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    In this study, one of mechanisms of transverse stability loss at super high forward speed is investigated. Towing tank test is carried out to observe the characteristics of the instability and it is confirmed that the instability has strong relationship to the change in running attitude and hydrodynamic roll moment due to high forward speed. And it has been also found that the dangerous maneuvering motions may be caused by heeling due to the transverse stability loss. Based on some existing empirical formulas to estimate the dynamic normal force (; lift) acting on planing hull, the estimation method of inception of the unstable phenomenon is proposed and its validity is confirmed through comparing with measured results.
  • -初期構造設計のためのツール-
    大高 慎自
    2006 年 3 巻 p. 225-231
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    This paper proposes Polynomial Displacement Function Method where elements are assumed to strain by a system of displacement functions of polynomial form in 3 variables with enough degrees of freedom to satisfy both equilibrium equations and connect conditions that are required to form a structure model as a ship hull. This method can calculate strength of structures contain panels, beams, frames, and pillars. It is also applicable to evaluation of elastic buckling stability and to vibration analysis by using the same model. The way of forming structure models is quite intuitive and easy to understand the relations between elements, substructures and their total structure. In this method, the element-model is developed in three steps. The first step is to enumerate all independent polynomials in 3 variables of 6th order that satisfy local equilibrium equations. A solid elastic body is assumed to deform in the way expressed by linear combination of these polynomial displacement functions. At second, the body is degenerated to a plate, to two-dimensions, with full degrees of freedom in deformation. Lastly, the shape of the elements and connect conditions are determined so as to three-dimensional structures can be built with the elements. In section 2,the calculation of degree-of-freedom and the requirements for structural elements are explained briefly. In section 3-8, the procedure of strength analysis by this method is shown. As local equilibrium condition is already satisfied in element displacement function, only total energy balance is considered. In section 9, some results by this method are compared with theoretical ones. One three dimensional structure example, a box-beam case, is illustrated and one actual case, a deck-vibration analysis, is presented.
  • 坪郷 尚, 正岡 孝治, 籔内 慎也
    2006 年 3 巻 p. 233-242
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    A new hydroelastic finite element for analyzing wave response of long plates on shallow water is presented. The plate has an infinite length, finite breadth and various flexural rigidity. The element is derived from weighted residual method with a Galerkin-type weighting function. We use not a polynomial but complex exponential function as the displacement function in the element. The performance of executing calculation by this method is very good. This method will be valid for flexible and large structures in initial design.
  • 山根 信, 田中 王治, 松田 漠, 藤久保 昌彦, 柳原 大輔, 岩尾 直樹
    2006 年 3 巻 p. 243-251
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    Steel tubular members of offshore frame structures can suffer from corrosion damages in marine environments. Paint coating is usually applied for tubular members in splash and tidal zones as a corrosion protection. A typical mode of corrosion experienced in those members is distributed pitting corrosions as a result of degradation of coating materials. On the other hand, tubular members in water and soil zones are generally protected by a cathodic protection without coating materials, and a general corrosion spreading all over the surface is a typical mode of corrosion. In order to evaluate the structural integrity and resulting failure risk of offshore frame structures with corrosion damages, it is important to investigate the residual strength of corroded steel tubular members. In the present study, compressive and bending strengths of steel tubular members with general or putting corrosion are examined. Surface roughness measurements are made for tubular members with general corrosions taken from the splash zone, and ultimate strengths under axial compression and pure bending are examined both experimentally and numerically. Pitting corrosions as a result of degradation of coating are modeled based on the existing related test results and ultimate strength is examined numerically. Based on the obtained results, the applicability of existing design formula for the evaluation of residual strength of corroded steel tubular members is examined.
  • 吉川 孝男, 吉村 健司
    2006 年 3 巻 p. 253-259
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    Recently, we usually use the numerical method to calculate the buckling strength of plate and shell structure. But at early design stage, we even now use the theoretical or some simplified formula to check the buckling strength. For most of typical plate and shell structures, the precise formulas of buckling strength have been developed. For the general buckling strength of ring-stiffened cylindrical shell under external pressure, the several formulas have been proposed, but the accuracy of those are hardly adequate. In those formulas, the effective breadth of ring-stiffeners is introduced, but the exact value has not been presented.In this paper, the calculation procedure of effective breadth is developed based on mechanical consideration of pre-buckling deformation, and the modified simplified formula of general buckling strength of ring-stiffened cylindrical shells under external pressure is also proposed. The accuracy of proposed formula is confirmed by comparison with numerical results.
  • 山下 洋一, 鳥越 雅喜, 阪野 賢治, 渡辺 大介, 南 二三吉
    2006 年 3 巻 p. 261-270
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    A method for the estimation of the CTOD fracture toughness δc from toughness results of bend specimens with a machined notch has been studied. The Weibull stress criterion is adopted as a brittle fracture criterion. The equivalent CTOD ratio β has been defined as the ratio of CTOD δ of the fatigue crack specimen to CTOD δ_M of the machined notch specimen (β = δ / δ_M) at the same level of the Weibull stress. CTOD tests are conducted for SM490A steel. It has been found that the equivalent CTOD ratio β is useful to convert the critical CTOD of the machined notch specimen to that of the fatigue crack specimens. The CTOD ratio β depends on the yield-to-tensile strength ratio YR; the steel with a high YR leads to a large β value than the steel with a low YR. Such dependence of β on YR has been verified with CTOD toughness data for various steel with different YR in the range YR=0.60-0.95 in FTC committee in Japan Welding Society.
  • 佐藤 宏一, 夛谷 元希, 吉田 泰三
    2006 年 3 巻 p. 271-275
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    Tanks of a spherical tank type LNG carrier are supported by the cylindrical shells by the name of "skirt". In the skirt, aluminum alloy A5083 having good low temperature properties is used for the upper part of the skirt connected to stainless steel SUS304 having low thermal conductivity is used for the lower part. In the connection, STJ (Structural Transition Joint) is necessary since the two materials cannot be directly welded. In the previous studies, A3003/SUS304L Clad Material Produced using Vacuum Roll Bonding has been proposed for the STJ and static strength and fracture strength have been investigated. In this paper, the new STJ is further studied for practical application to LNG Carrier, including fatigue test and installation in a ship in service. As a result, long-term integrity of the new STJ with lower manufacturing cost has been confirmed.
  • 桃木 勉, 米山 治男, 平石 哲也
    2006 年 3 巻 p. 277-284
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    Recently, very large floating structures (VLFS) are proposed for use as an airport, disaster prevention bases and offshore wind power generation system, and so on. There are a lot of researches on hydrodynamic response of the VLFS in waves. However, it is necessary to research the influence of the discontinuity of the stiffness when the floating units of different types are connected with each other or the joints of floating units have a special shape. In this research, we conducted the hydraulic model experiment on 1/50 scale, and analyzed the elastic response of the test model using VODAC (Very Large Floating Structure Oriented Dynamic Analysis Code). The depth to length ratio of the model is relatively large, and its joint part is composed of multiple materials. VODAC developed by University of Tokyo calculates the hydroelastic response of a large floating structure fully considering the hydrodynamic interaction effects. Two kinds of beam FE-models are employed as a structural model; one is the model that arranges equivalent beam elements on the neural plane, and the other the model that represents the deck, bottom and vertical wall using beam element individually. We discussed suitable structural modeling technique by comparison of an experiment and analysis.
  • -短辺方向荷重を受ける場合の崩壊挙動の再現-
    石橋 公也, 藤久保 昌彦, 矢尾 哲也
    2006 年 3 巻 p. 285-292
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    The Idealised Structural Unit Method (ISUM) is known as a simple but efficient method to simulate buckling/plastic collapse behaviour of structural systems. To perform collapse analysis of structures composed of girder webs and plate flanges such as a ship's double bottom structure, it is necessary to develop a new ISUM element which can simulate buckling collapse behaviour of a girder web with a cutout. In the present paper, a series of collapse analyses with conventional FEM is firstly performed changing the size, the shape and the location of a cutout. On the basis of the results of FEM analyses, a new ISUM element which can simulate the buckling collapse behaviours of a rectangular plate with a cutout subjected to thrust in the transverse direction is developed. Through comparison of the calculated results with those by FEM analysis, the applicability and the accuracy of the new ISUM plate element are demonstrated.
  • 中井 達郎, 松下 久雄, 山本 規雄
    2006 年 3 巻 p. 293-301
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
    Pitting corrosion is a great concern when the integrity of ship's hull structures is considered. Corrosion pits with a conical shape are typically observed on coated hold frames in way of cargo holds of bulk carriers which exclusively carry coal and iron ore. In the present study, a series of non-linear FE-analyses has been conducted to investigate the effect of such pitting corrosion on local strength of hold frames using various structural models, that is, collapse models accompanying no buckling, lateral-torsional buckling models, local buckling models, shear buckling models and web crippling models. It has been revealed that the ultimate strength obtained in the present analyses for all the structural models except shear buckling models could be well predicted by the empirical formula, which was developed in the previous study to estimate the ultimate strength of steel plates under compression and shear. In the case of shear buckling models, it depends on the web thickness whether the empirical formula could be applied or not.
  • 2006 年 3 巻 p. 303-305
    発行日: 2006年
    公開日: 2006/12/26
    ジャーナル フリー
feedback
Top