Not only between two or more countries but between some regions in a big country like the U.S., there are a lot of problems for allocation and distribution of empty sea-borne containers because of international imbalance of trade situation. Authors presented an effective planning method for distribution of empty containers between two or more countries. For the distribution problem in a country, we propose another planning method since this problem contains different characteristics, i.e., short period movements of empty containers, and no consideration of state of container (i.e., full container or empty container). The distribution problem defined as the transshipment problem is formulated as transportation problem which is relatively easy to solve optimally. A case study for the distribution in the U.S. for 6 weeks shows that the total distribution cost by our method is 20 per cent less than that of the real one.

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The purpose of this report is to estimate the dangerous zone when a tanker leaks floating hazardous liquid cargo by an accident. The differential equation about the radius of liquid spreading on the sea surface has been obtained from the relation between its potential, kinetic, and viscositic energies, and from its vaporization. Furthermore numerical calculations have been made of several kinds of chemical substances by this equation. Its values have proved to agree with those of numerical simulations by the Simplified Marker and Cell method in case of an actual leak from a tanker. On the other hand, the vaporized gas concentration in atmospheric diffusion it has been obtained from a numerical simulation based on the Box Model. These results show that the dangerous zone becomes wider with an increase of saturated vapor pressure until it reaches nearly almost 155mmHg (n-hexan). The dangerous zone stretches far 800m from the broken point of tank when 150m^3 volume of n-hexan has been diffused into the neutrally stable atmosphere with wind velocity of 0.5m/sec.

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This paper describes the design and operation results of computer assisted simulator for integrated transportation systems analysis. The function of transportation is to distribute cargo safely, efficiently and quickly in the multiple processes between the difference of utilities in place and time, and finally it is to give possession and use utilities which include consumer surplus to the user and also it is to contribute to the national welfare. As the systems analysis of the multiple processes includes the tradeoff relations among each activity or service which composes transportation system, evaluation of the system should be carried out making use of the criterion of economy optimality in total optimization. The author designs and builds simulation model of the integrated transportation system which consists of truck haulage, storage in warehouse, handling at port, sea navigation, etc. And truck load, inland distance, cargo handling rate, number of berth, ship deadweight, ship loading factor, ship speed, demand of cargo, etc. are operated as exogenous conditional variables. The simulation of integrated transportation is carried out about one year long in the step unit time of one hour on the mini computer, and it takes about ten to twenty minutes for one case operation. The states of simulation running and statistic of results are displayed on the graphics, and also segment and total physical distribution costs are calculated and are displayed on the graphics and are printed out. Tradeoff analysis among elements of transportation system and total evaluation can be carried out easily making use of output results on many case studies, and also this developed on-line system can be used as the support for the decision-making for us.

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This paper is concerned with an evaluation for developing an expert system for navigation at sea. The purposes of this study are as follows. (1) To discuss how to evaluate the expert system for navigation at sea. (2) To estimate future image of the expert system for navigation at sea by evaluating sub-systems which had been constructed by the authors. This paper shows the methods of quantitative and qualitative evaluation and the results of measurement and research by using these methods. The summary results of the study are shown below. (1) In order to evaluate the expert system for navigation at sea, the authors have proposed items, methods and so on. According to these items, sub-systems which had been constructed by the authors have been evaluated. (2) Consideration to rule chaining (forward, backward, procedure) for inference and improvement of displays of outputs are mainly required for future development of the system. (3) The size of the inference engine and the number of the rules of the expert system for navigation at sea have been estimated and discussed neccesary computers to develop the system.

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The authors have designed a two-axis controlled satellite tracking mechanism with a parabolic antenna which enables us to furnish vessels with a simple and inexpensive satellite broadcasting reception system. The maximum rotating speed of both azimuth and elevation angles is about 10°/sec. After examining the dynamic response on a table which simulates the various conditions of rolling on the sea, we installed the device on board the training ship "HOKUTO MARU" (5856 G/T) which was to steam in Japanese waters and the southern ocean down to western Australia. It proved to work excellently with a parabolic antenna of 50cm or 75cm in diameter even on a rough sea in the area down to lat. 20°N. The southern limits of the satisfiable picture reception were at lat. 18°N and long. 134°E on the way to Australia and lat. 16°N and long. 138°E on the way back, with an antenna of 120cm, on a slight sea condition. The profile of the power flux density of BS on the sea is estimated by C/N values observed along the route. The mechanism was also applied successfully and effectively to the reception of the images from GMS in the southern hemisphere.

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Images of ocean seafarers were measured by three different kinds of college students, college of mercantile marine, general state-run university and private women's college. The quantification method III was applied, and categories' weight were classified into 2 axes (Factor I and II) which denote professional and emotional evaluations of seafarers. Mercantile marine students have better images than other two types of students.

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The authors have previously made clear the relationship between human dynamic response and ship oscillatory motions. In this paper, based on the discriminatory analysis, the threshold value within which the subjects can maintain their balance for ship accelerations is estimated statistically. In order to evaluate the distribution of acceleration occurred on the ship deck, the towing experiment with model ships and OSM-calculations were carried out. Furthermore, based on the threshold value and the distribution of the accelerations on the ship deck, the working environment in regard to the balance of the subject was estimated and discussed.

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The crew possibly have the case to be obliged to escape from ship by a shipwreck. Then, they will find themselves in the sea water where they must stay afloat until they are rescued. Sometimes, they may lose their lives on the sea. Estimation of survival time of persons adrift on the sea or in lifesaving appliance is necessary for rescue ones before they loss their lives. In the present paper, reported is estimation for tolerance time. The core-temperature of persons are presumed using three kinds of data, that is, actually occurred shipping casualty, thermal resistance of persons clothed or in lifesaving appliance, and human subjects of this experiment in the cold water.

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This paper shows the result of an experimental study on apparent hue of the lightbuoy at sea. This experiment was investigated by employing the colour naming method. The colour naming method of 10 grade evaluation was adopted. Five observers with normal colour vision and visual acuity and two observers with deuteranomaly and normal visual acuity, participated in this experiments. The experiment was operated in the visinity of Tokyo port west fairway where L-1 type lightbuoys of M.S.A. (Maritime Safety Agency) are set up. The results of this experiments are shown as follows: 1. Not only before but also after sunset, it is hard to recognize both body colour and light colour of the lightbuoys. So it is suggested that strict lookout should be paid with special caution during that time. 2. When the recognition for body colour of lightbuoys was compared with that of light colour at the same distance, the red colour is more clearly recognized than the green colour in any weather condition. 3. Body colour comes to be recognized as the stable colour after the middle term of twilight (Nautical twilight). 4. On the visibility of deuteranopic observers, the following characteristics appear; a) In the daytime, they can distinguish the body colour more clearly under fine weather than under cloudy weather, but as for the recognition of green buoys, it shows that the remarkable changes depend on the weather condition. b) In the night, it seems they recognize the light with much white ingredients as if green or red colour was mixed with based white light. c) Their recognition of the colour visibility changes greatly and unstably.

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The position fix accuracy regarded as necessary by ship masters and officers depends upon several factors, such as ship safety related factors and ship operation related factors. It is our objective to specify these factors and evaluate quantitatively their contributions in this dependency. For that purpose, questionnaire survey was conducted and the analysis was done by use of Analytic Hierarchy Process. Results show that safety related factors contribute to the dependency more in the harbor area than in the ocean, and also job rank has something to do with the evaluation of the factors in the ocean and coastal area but not in the channel and harbor area.

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The Vessel Traffic Services, abbreviated as VTS, is for the safety and efficiency of vessel traffic. It is often understood as "Vessel Traffic Management System, VTMS". Following to the first survey in 1977 and the second in 1982 on VTSs in the world, the third survey was made in 1987 by employing questionnaire with feedback method, i.e., the answers filled in questionnaire format are compiled to an interim report in March 1988, which has been sent back to responders for revision. The number of VTSs having answered is 160 and, by adding 43 VTSs with the answer in the previous survey, 203 VTSs are surveyed. The number of surveillance radars of surveyed VTSs amounts to 402 which covers about 80% of existing VTS radars in the world. Revised data are analyzed with respect to various factors; category of traffic management, authorities and participants, cost, areas covered by VTS, information and surveillance facilities. Emphases are placed on quantitative analysis to find median values and correlations between closely related factors.

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When a mooring ship with a large exposed area receives a strong land wind, it may cause an accident of a ship separation from a quay wall. So far storm bits and tugboats are used as counter-measures for the problem. If the water body between the ship's side and the quay wall is surrounded by a tight film and then the water is pumped out, the water pressure resulted from the difference of the water level of both ship's sides will push the ship toward the quay wall. In this paper, it is proposed that the above force can be used for the prevention of the ship separation from the quay wall. Some experiments are carried out to verify the principle.

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There are not so small number of papers which dealt the item of inclined bottom effect to a moving ship. One of the most famous and epochmaking papers is written by R.W.L. Gawn in 1950. Including this Gawn's research, almost all of the papers dealt a homogeneous bottom; in other words inclined bottom continuing far away from behind the ship to forward. My paper handles the problem of partially existing inclined bottom, that is, a ship sails above a flat bottom, then suddenly she senses an inclined bottom effect, and after about two ship lengths' run, she resumes to above the flat bottom again. I aimed to get qualitative data through having model ships run inertially in a tank in which small portion of an inclined bottom had been put on a flat bottom. Two model ships of a general cargo ship and a tanker of on bulb, had a fixed rudder and no screw propeller. Model ships were pushed ahead using a catapult and after that they run completely free without any actual handling. Notwithstanding the total absence of actual handling, the characteristics obtained through several repeated experiments under the same condition were almost identical. The summarization is as follows; (1) the influence of a partially existing inclined bottom to a moving ship above it is basically the same with those of a homogeneous one, (2) the influence becomes more remarkable as the incline of the bottom increases, (3) the influence depends on the depth-draft ratio and the smaller the ratio, the greater the influence and, (4) the model ships turn the head to sail toward the deeper side, consequently the tracks curve to the deep.

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Nonlinear differential equations derived from a mathematical model of a ship rolling motion at sea have been solved by Runge-Kutta method. Based on the solutions, Poincare mapping functions have been calculated from a strobe points decided by ship motion theory. Experimental data of ship's motions have been analyzed. Utilities of the mapping in this experiments have been discussed.

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In the previous report, the authors have pointed out that manoeuvring motions of ships in harbours can be briefly divided into and composed of several kinds of elemental manoeuvres, such as course keeping and changing with/without speed changing, turning drifting and so on. In the present report, an attempt is done to analyze a manual steering system of directionally unstable ships under speed changing, putting a special emphasis on the allowable limit of instability. At first, the frequency responses of unstable ships are examined and the specific characteristics of phase lag of unstable ships are pointed out. Summarizing in short, the directional stability and the rudder effectiveness of ships under decelerating become less but the phase lag of ships under the condition is not so different from the one under constant speed. Secondly, the performances of human operators are investigated by the manoeuvring simulator of Hiroshima university and their models are identified statistically from manual course-keeping simulations under constant advance speed. It is pointed out from such studies that human operators can adjust easily their control gain, responding to the properties of ships but they have a limit in compensating the phase lag of unstable ships for stabilizing the manual course-keeping system. The allowable limit of the phase lag to be compensated by human operators is roughly estimated about 30 to 50 degrees. Then, the difficulty of manual course-keeping for such ships is characterized by the phase lag to be compensated by human operators. Taking the above into consideration, it is concluded that the difficulty of course-keeping under decelerating differs little from under constant speed. The above conclusion is finally made sure of from manual course-keeping simulations under decelerating.

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International Maritime Organization (IMO) is going to establish the maneuvering performance standard, which defines practical indices for typical modes of ship handling in various navigation conditions. Among the indices, those of course change test are most practical and useful ones, which are directly applicable for course change maneuver. A parallel course shift test is proposed and investigated by means of computer simulation. Congested traffic conditions require the ship to perform collision avoidance maneuver, which is mainly composed of course change and parallel course shift. Wind effects on the performance in parallel course shift are examined in order to evaluate the wind as a factor of natural environmental condition for ship navigation and its effects. Practical charts and diagrams of the performance indices' and concrete guidelines for the correction in ship position control are obtained by the parallel course shift tests.

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