Abstract

1. Human Being as a whole was given the legal status, to some extent, as a subject of International Law. This is the first time in Human History.
2. The right of sovereign states over the ocean transformed to the duty of them to Human Society.
3. Harmonization between Environment and Development in the Ocean Space have to be the most urgent international policy task today.

The use of the ocean in the urban development seems to be promising in view of the fact that further use of land is limited in urban areas due to vast growth of population and needs of many housings, business buildings, shops, infrastructures, factories and transportations. In such marine countries as Japan, the use of ocean space is encouraged on the standpoint of invulnerability to earthquakes, reduction of gravity forces, global warming, attraction of waterfront and easiness in transportations. This paper discusses the feasibility of such floating structures serving as infrastructure.
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Singapore is a unique city-state. It is one of the smallest countries in the world with a relatively tiny island area of about 660 square kilometers today. As Singapore is without any natural resources, her people are, and will always be, the most precious resource. Presently, her population is about 4 million and this number is expected to grow to about 5.5 million in the year 2040. In anticipation of the projected population growth , economic growth as well as the recognition for enhancement of quality living and working environment that are sustainable into the future, Singapore is continually seeking and developing innovative ways to optimize both her land space and sea space.

This paper focuses on the multiple utilization of the precious sea space in Singapore coastal waters. These usages include port and harbour development for Singapore's megaports that serve ships plying a region stretching from India to Japan and beyond, land reclamation for airport, utility, residential, industrial and recreational needs, marinas for leisure activities, landfill for waste materials, coastal fisheries, and floating structures for piers and industrial purposes. The paper will trace the historical developments of the abovementioned usages, and also highlight the new innovative technologies used. New concepts for future utilization of sea space will also be discussed.
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Time-domain, hydroelastic analysis of offshore structures can be�@described as a two-field problem. The structural motion must be transferred to the fluid model and the resulting fluid pressure at the fluid-structure interface must be transmitted from the fluid model to the�@structure. The displacement and pressure mapping is difficult and�@mathematically imprecise when the structural mesh and the fluid mesh describe two distinct three-dimensional surfaces. In this paper, three mapping strategies based on the Penalized Discrete Least-Squares (PDLS) stress recovery (smoothing) technique are presented. These strategies attempt to conserve the work done by hydrodynamic forces when obtaining the global structural nodal forces. The merits and the disadvantages of these strategies are discussed and illustrated with several examples.
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Floating causeways are used by the U.S. Navy to transport materiel from ships to shore when the water depth is very shallow. This work is on one of the 1200ft-long (365.7m), floating causeways (FC) called INLS, and which is moored in shallow water of depth less than 32 ft (9.8m). The FC is made up of modules connected to each other either flexibly or rigidly. The width of a module is 24ft (7.3m), but the length varies from 80ft (24.4m) to 160ft (48.8m). Several different mooring-line arrangements and mooring lines with different properties are investigated. The study also allowed the presence of ship(s) tied to the FC during both the static and dynamic analysis of the problem.

The overall objective of this study is to estimate the mooring-line tensions as a result of steady current, and wave action. In the static analysis, the modules are assumed flexible. The goals of the static analysis is to obtain a realistic mooring-line arrangement, and to establish a configuration on which the dynamic, wave motion analysis is based. In the dynamic analysis, the modules are assumed to be rigid but the connectors are flexible. Linear theory is used to estimate the response of the FC and the resulting mooring-line tensions.

We will describe the physical and mathematical models used in the study. Various mooring-line arrangements are included in the study to simulate when some of the anchors are dragged.

The static analysis shows that there can be substantial differences in mooring tensions depending on the site, metocean, and mooring data specified. Some of the sensitivity is due to the very shallow depth in that significant tensions can result from small displacements of the FC. Load balancing between mooring lines is therefore quite difficult to achieve.

The dynamic analysis shows that extremely large mooring tensions are estimated, and that they are partly a result of resonance, and partly a result of very large, catenary-line stiffness in this shallow-water problem. In addition, the very large horizontal distance water particles move in shallow water causes the FC to have extreme horizontal motions that in turn contribute to the very large mooring tensions predicted. However, modifying the line stiffness can reduce the extreme tensions dramatically. Moreover, the viscous damping that is not considered in the present study can be a source of significant reduction in mooring-line tensions. A follow-up study on this issue will also be discussed briefly.
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A new type Very Large Floating Structure using Submerged Plates (Sub-Plate VLFS) is proposed for extending the operational area of VLFS to deeper sea with reducing environmental problems. The system consists of a Floating Breakwater using Submerged Plate (FBSP) and a VLFS with submerged plate. FBSP not only decreases incident wave height for VLFS but also generates a steady flow, which enhances the exchange of seawater around VLFS. A series of experimental and numerical studies on the wave dissipating capacity, motion, mooring forces and structural strength of Sub-Plate VLFS has been performed, and the high feasibility of the system for the sea of 100m depths has been demonstrated. This paper deals with the basic concept of the system, together with the conceptual design of proto-type system and its performance as a breakwater.
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In recent research, it has been cleared that the motions of pontoon type very large floating structures (VLFS) are dominated by the dispersion wave that is induced by the floating structure and the fluid interaction. Incident wave excites the weather side of the structure, and then the deformation is propagated over all the structure. The deflection wave propagation to the main part of VLFS is not desirable, because the deformation requires the large area of high strength structures and the motion might affects the function of VLFS. In this study, the edge shape of VLFS that restrains the deformation propagation has been investigated. To evaluate the effect of the improved edge form, a program to calculate the response of VLFS that has arbitrary horizontal outline has been developed. It has been confirmed that the notched edge reduces the deformation of the inner area of VLFS. Furthermore, to reduce the motion effectively, a relation between the edge form and the incident wavelength was investigated.
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The objective of this project is to determine the ultimate strength of imperfect stiffened and unstiffened plates subjected to compressive inplane loads. The imperfections can be due to initial deflection, welding residual stresses, presence of holes, corrosion, dents, or cracks. The resulting strength equations are to be used for guidance in design, and therefore have to in a simple closed-form format.

The approach adopted in the paper is to perform extensive parametric non-linear finite element analyses for many stiffened and unstiffened plates with varying geometric properties, e.g., aspect ratios, plate thickness, stiffeners dimensions, etc. The ultimate strength of each stiffened or unstiffened plate is then determined with the presence of one or more type of damage of increasing severity, using non-linear finite element program. Both, material and geometric (large deformation) non-linearities are included in the finite element analyses.

The results were than used to develop closed form equations for use in design. The typical procedure for obtaining these equations was to start with well-established equation for a " perfect" stiffened or unstiffened plate, and modify it by a reduction factor that depends on the type and magnitude of the damage. The reduction factors were developed on the basis of the finite element results, i.e., the finite element results were used as if they were experimental data. Only well-established equations for the " perfect" structures were used, e.g., the Perry-Robertson's equation for stiffened plates and Frankland's equation for unstiffened plates.
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A simplified method of collapse analysis of a pontoon-type VLFS in waves was developed as a tool to examine a global collapse behavior of a VLFS under abnormally severe wave excitations and thereby to ensure a redundancy of the structure as a whole. The idealized structural unit method (ISUM), which is a very efficient method for buckling/plastic collapse analysis of stiffened-plate structures, was employed to drastically reduce the degrees of freedom to solve for. The proposed method was applied to a time-domain collapse analysis of a prototype VLFS model in regular waves. The deck and bottom plates were modeled by ISUM plate elements, and the girder and floor by conventional beam elements. A concept of a super ISUM element was introduced to further reduce the degrees of freedom. A series of collapse analyses was performed for the 1650m x 495m partial model that exhibited the elastic response similar to that of a whole model in a specified regular wave condition. The basic features of collapse behaviors of a pontoon-type VLFS are discussed, including the effect of structural collapse on the dispersion relationship of deflection.
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Although it is expected that the impact of very large floating structures (VLFS) on the natural environment is insignificant, there had been some anxious about the shading effect on marine lives due to the floating body covering sea surface. However, before the Mega-Float projects started, there was little actual data showing the extent of environmental impacts by VLFS. Therefore, investigations of environmental impacts by VLFS had been conducted under the cooperation of Technological Research Association of Mega-Float. During the Mega-Float Phase-II experiment in Tokyo Bay, continuous monitoring of vertical profiles of water temperature, salinity, dissolved oxygen and chlorophyll-a, and so on were carried out at several fixed stations below and around VLFS model. Manual samplings of seawater had been also carried out in order to investigate spatial distribution of water quality in detail. The results indicated that VLFS would hardly affect the physical environment around it as far as there exists significant current at the mooring site. However, it was found that local water quality was affected mainly by sessile animals attached on the surface of VLFS. Based on the field observation around the Mega-Float model, an ecosystem model was developed for the prediction of marine environment affected by VLFS. The model includes the effect of sessile animals on the structure and coupled with hydrodynamic model predicting physical environment in the bay. It was applied to numerical simulations with temporary varying boundary conditions in order to verify the applicability for dynamically changing real phenomena. The continuous observation data around the Mega-Float model is very useful for the verification of the results of numerical simulations. The results showed that the model could predict the dynamic change of physical environment in estuaries fairly well. By the process studies using this numerical model, it was confirmed that the influence by sessile animals on VLFS is more significant than shading effect of the floating body.
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The environmental impacts of an imaginary very large floating structure (VLFS) on marine ecosystem are examined. From the previous studies, it is expected that a lot of sessile organisms adhere to the bottom surface of the VLFS, and they have some effects on their surrounding water quality. To discuss the extent of these impacts quantitatively, numerical simulation by means of coastal ecosystem model is one of the useful tools. First of all, marine ecosystem in Tokyo Bay is simulated in the case when the imaginary VLFS does not exist, and coastal ecosystem model is validated by comparison of predicted results with observed ones. Further, numerical simulations are conducted in the case when the imaginary VLFS, whose length is 5 km and width is 1 km, is moored off Oppama or off Haneda in Tokyo Bay. As a result of several computations, it is revealed that growth rate of the sessile organisms adhering to the bottom surface of the VLFS are smaller in the sea area off Haneda, where current of seawater is slow. It is because particulate organic matter (POM) and oxygen are not supplied sufficiently in the area under the VLFS. On the other hand, in the sea area off Oppama, seawater flows southward constantly at the speed of about 0.1m/s, so POM and oxygen are supplied appropriately to the sessile organisms. Hence they can grow by uptake of POM around them, and can sustain their biomass. When the VLFS is installed off Oppama, the biomass of sessile organisms per unit area is much larger than that of suspension-feeding macrobenthos, which has the same functions as the sessile organisms, in the several tidal flat estuaries in Tokyo Bay. So the sessile organisms adhering to the VLFS may have large impacts on circulation of matters such as carbon, nutrients and oxygen. Therefore, the impacts of filtering POM by the sessile organisms on carbon circulation are examined. As a result, it can be said that the sessile organisms retain POM in Tokyo Bay, which may otherwise flow out from the bay to the outer sea.
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A numerical model to simulate the water quality around a Mega-Float in Tokyo Bay is presented. The model consists of two parts, a hydrodynamic model and a marine ecosystem model. Tidal currents, water temperature, salinity and water density are calculated in a bay with/without a Mega-Float in the hydrodynamic model. A marine ecosystem model including the floating matters such as nutrients, phytoplankton, zooplankton and organic matters are extended to include not only the effects of marine mussels attaching on the bottom of the Mega-Float but also the benthic effects with the mussels fallen down to the sea bottom. The marine mussel is modeled as a macro benthos similar to an ecosystem model for a tidal flat estuary. The variation of water quality in the case of with/without a Mega-Float of 5 km length, 2 km breadth and 1 m draft are given in graphics. The environmental impact on marine environment at each location is evaluated with two evaluation functions that are newly proposed to evaluate the changes of the water quality of the bay due to the installation of the Mega-Float.
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In order to investigate the environmental problems of the Earth, it is necessary to periodically observe the ocean state to determine environmental changes. This needs to be done over very wide areas. Since autonomous underwater vehicles (AUV�fs) have an advantage that they can swim freely without restriction of tethered cable they are very useful for ocean observation. It can be said that AUV�fs are increasingly finding practical application worldwide. It is expected that the demand for the development of highly intelligent AUV�fs to undertake complicated missions would increase greatly over the next few years. The technique of autonomous observation of underwater structures using AUV�fs with highly intelligent features developed in the Institute of Industrial Science at the University of Tokyo, and our perspectives of AUVs, are the subject of the talk.
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The diffusion and convection flow will occur concurrently in the CO₂ storage well by being induced from the ocean current and results in the CO₂ diffusion into the ocean. Author studied these phenomena in the ocean and the sea bottom basin in which liquid CO₂ was sequestrated in about a partial depth. The geography of the sea bottom was approximated by the typical two or three-dimensional shape. The differential equations of the boundary fit coordinate system and its FDM scheme were newly developed for this complicated topography. The characteristic properties and behaviors of CO₂ in seawater were taken into the analysis. These include the flux of mass transfer through hydrate, the expansion of water due to CO₂ dissolution and heat of dissolution and the diffusion coefficient in the benthic boundary layer. The numerical solutions of flow dynamics and concentration were obtained by FDM, and the results of flow velocity, CO₂ concentration, variation of pH distribution and CO₂ flux into the ocean and its accumulations were indicated. Through the studies the method of partially filled storage�@in connection with the sea bottom topography was evaluated.
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We have proposed the advanced mining system of methane hydrate by replacing CO₂ hydrate and the sequestration of CO₂ under high pressure and low temperature condition. In this paper we discuss on fundamental properties of formation and dossociation of gas hydrates to reveal the dynamic behavior in the process of replacement and reformation of CO₂ and methane hydrates.
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Methane hydrates occur in offshore Japan with possibly large quantities. In order to promote its utilization as an energy resource, the Japan's Methane Hydrate Exploitation Program (MH21 program) was plotted out under the lead of the Ministry of Economy, Trade and Industry (METI) and initiated by the MH21 Research Consortium in FY 2001. The MH21 program is a 16-year-project and includes the study of offshore development system to enable economically and technically feasible production of methane gas from methane hydrates. This paper describes the outline of the MH21 program and the R&D plan of methane hydrate development system as part of the program.
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The Floating Structure Technology was developed in order to utilize the seashore for human activities. The structure is generally classified into two (2), the pontoon type, and the semi submersible type. Large-sized floating structure is often called as Megafloat and can be used for the construction at the sea of airport, wharf, oil-storage base, and urban space for industry or housing. It is one of the least expensive ways to create a space in the shallows due to its characteristics as floating system. Furthermore, floating base has less negative effect on the ocean environment as compared with other methods like reclamation work. Other advantages of this technology includes; safe from earthquake and easy to move from one place to another. In 1995, after a devastating earthquake hit Kobe, sea transportation proved to be the most effective route for support activities such as food supplies and medical services. Restoration works and other support activities through land transportation were extremely difficult because of the serious damages on road and rail systems. The movable floating base, which allows easy access from the sea to the disaster area, was planned by applying the technology of the floating structures. This is carefully planned and engineered for full utilization by allowing it to host urban facilities such as car parking, fishing park, food chains, and a storage space for first aid materials. By serving these urban functions, the structure in return generates fund which could be then used for maintenance purposes. In times of disaster, the base will be towed towards the disaster area by tugboats and emergency materials coming from the ships will be transported to the disaster area through the floating base. Other functions that can be served by this floating base include emergency heliport, information center, medical center, stockyard and among others. In 2000, the Japanese government as part of precaution measures against disaster has constructed three bases located in Tokyo, Nagoya, and Osaka. These bases are expected to play important role in times of calamity.
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Technological Research Association of Mega-Float (hereinafter referred to as "TRAM") was established in April 1995 and has carried out "Research and Development of an Ultra Large Floating Structure" for a six-year program. This research was successfully completed in March 2001 with sufficient results regarding technical possibility of large floating airport. TRAM�@was terminated and the technologies are succeeded to Shipbuilding Research Centre of Japan(Referred to as SRCJ). Meanwhile, recently Haneda Airport along Tokyo Bay is planned by Japanese government to have an additional runway in near future. Regarding construction method of a runway, 3 methods are nominated as candidates, namely Floating Structure Type as called mega-float, conventional reclamation method and pile system with upper structure. This article introduces outline of result of mega-float research and also a floating runway for Haneda airport proposed by The Shipbuilding Association of Japan developing results of mega-float research project. Details of subject are as follows.

• Layout of floating airport for research and a new runway for Haneda
• Design conditions in both cases
• Outline of runway structure for both cases
• Hydro-elastic motion by waves in both cases
• Mooring system for both cases

This paper deals with development of a computer program for prediction of dynamic response of a floating bridge subjected to both irregular winds and waves in the time domain. In this paper, the floating bridge with separate-type floating foundations is considered. The floating foundations are modeled as rigid-bodies, each of which having six degree of freedoms, and the super-structure, which connects the floating foundations, is modeled as linear elastic-body. The mooring systems are modeled as springs having non-linear restoring force characteristics. Because of the frequency-dependence of the radiation wave forces, the memory effect has been taken into account in the time domain. The methodology of the developed program is presented with several numerical examples for a typical floating bridge with separate-type floating foundations. At the workshop, some video on wind-tunnel experiment of a floating bridge model located in water tank will be presented.
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Relating to recent environmental changes in Isahaya Bay and Ariake Sea, studies on the reduction of tidal amplitude in Ariake Sea are reviewed first. The effects by the dike in Isahaya Bay on the flow and density field in the Sea are studied by a numerical model. Water flows in Ariake Sea and the tidal exchange of the reservoir inside the dike are simulated when the floodgates of the dike are opened. Experimental results on the flow and tidal exchange of the reservoir by using a simplified model are also introduced.
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We conducted numerical and experimental research on the effects of equipment for enhancing water quality. Hydraulic models set in a rotating tank and ocean flow models were adopted for experimental and numerical simulations, respectively.
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A phenomenon that seaweed bed changes into barren ground is called Isoyake in Japanese. There are many explanations for the cause of Isoyake, but the mechanism has not yet clarified. At Muroto area in Shikoku Island, one of the causes of Isoyake is the approach of Kuroshio Current, which is high-temperature and low-nutrient content, to the coastal area. Kochi Prefectural Deep Seawater Laboratories reported that some patches of seaweed bed recover near deep ocean water discharged points. Deep ocean water has low-temperature and high-nutrient content characteristics. This suggests that the deep ocean water discharge possibly restores seaweed bed from Isoyake condition.

The purpose of this study is to clarify the mechanism of the recovery of seaweed bed where deep ocean water is discharged. The research approach consists of field survey, biological experiment and ecosystem modeling. We investigate biomasses of seaweed and its feeders, such as a sea urchin and several kinds of fish at Muroto area. We also carry out experiments to obtain grazing rates of the sea urchin and fish in the tank. The obtained data are used for developing an ecosystem model, which includes the grazing pressures of the sea urchin and fish. The results of these investigations show that the grazing pressure, which depends on the deep ocean water concentrations, is one of the important factors for the seaweed bed recovery.
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The bathymetry of the coast around India, where cold water at a depth of 1000m is available at about 40 km from the shore necessitates the use of a floating platform to house the OTEC plant. NIOT proposes to build a 1 MW floating OTEC plant working on a closed cycle off the coast of Tamilnadu. The aim of the demonstration plant is the design, manufacture, and erection commissioning and performance evaluation of a floating OTEC plant rating 1 MW gross. In addition to the power module operating on closed loop ammonia and associated turbine generator, control system technologies, this will imply the need to develop and assimilate some technologies. For example,(1) Design, Manufacture and Performance evaluation of high quality, compact heat exchangers with phase change under marine conditions., (2) Measurements and development of methods for control of bio fouling in heat exchangers, (3)Structural analysis under marine environment of 1.0 diameter, 1000 m long HDPE pipe coupled to a floating barge, etc.

In this paper, it is presented the concept proposed and the detailed engineering and technology is shown.
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