bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tests On The Wave Power Generator "Kaimei"
Authors: Miyazaki T. , Masuda Y. 
Published: October 2008

1. INTRODUCTION
Although the possibility of utilizing wave energy has long been considered, the only wave power generator put to practical use in the world today is a navigation lite buoy. Thus, the utilization of wave energy is still limited to a small scale. The Japan Marine Science and Technology Center (JAMSTEC) has been carrying out a five-year developmental research project on a large-output wave power generator since 1976. Since the objective of the research is the conversion of wave energy into electricity, a wave power generator, " Kaimei", was constructed in order to perform two stages open-sea tests during two years. From these tests, technical data on the wave power generation system was obtained and will contribute to the realization of actual harnessing of wave power. Below is a portion of the data from the open-sea tests.

2. PRINCIPLE OF CONVERTING WAVE POWER INTO ELECTRICAL POWER
Various applicable methods for the conversion of wave power into electrical power have been proposed by experts in the world. However, JAMSTEC has been concentrating its efforts on the research of a wave power generator employing air turbines. In this type of generator, a bottomless box is floated on the surface of the sea, and an entering or exiting flow of air is actuated by the upward and downward movement of the water in the box. An air turbine driving a generator are installed on the box and utilize these air currents, to generate electricity.
After various types of model tests, the steelmade 80-m long, l2-m wide Kaimei was constructed. The body of the Kaimei consists of four buoyancy rooms and a number of air pump rooms where wave energy is converted into air flow. The following are its characteristics.As a floating structure, the Kaimei is moored with chain and anchors.Since it is a ship-like buoy, always heading to the waves in order to reduce mooring force.The model tests have proven that wave energy can be absorbed sufficiently, even when the waves are received on the bow.The absorption of wave energy is related to the wave length, and maximum efficiency is achieved when wave length is 8O% of the buoy length.Calculation of the hull strength is facilitated by the design of the Kaimei as a ship-shape structure.There was no observable affect on output caused by differences in mooring systems.No mobile apparatus were installed at areas exposed in the water.The slow movements of the waves are transformed into high-speed movements by the use of air turbines.The energy converting apparatus does not directly receive the shocks from the waves.The Kaimei is not affected by the marine fouling to its surface.

3. OPEN-SEA TESTS
The open-sea tests were performed twice. The first tests, from August 1978 to May 1979, employed three generator units. The second, from August 1979, is a joint research project involving five countries as part of an IEA undertaking.
Fatigue Life Prediction Of Tubular Nodes
Authors: Lieurade Henri Paul , Gerald Jean P. , Putot Claude J. 
Published: October 2008

ABSTRACT
Large scale specimens of X-joints were tested in fatigue, either in tension or in in-plane bending (R=O.1). Similar specimens (size ratio 1/2) were tested in order to estimate the scale effect. y was chosen here from 8 to 12, at the limit of the validity of any shell-theory. In each node, one brace joint was heat-treated and the other was left as welded. The specimens were instrumented by strain gauges.
During monotonic static loading, the measured distribution of stresses shows that the Effective stress concentration factor KE can be defined as a product of two factors KE =KG × KL, where KG reflects the Global geometry effect of the intersection of the two shells and KL the influence of the Local shape at the weld toe.
During the fatigue test, the crack growth and the evolution of strains along the weld-toe were monitored. On the basis of the obtained results an elementary theoretical model for life prediction is proposed which takes into account the stress redistribution due to the crack growth.

INTRODUCTION
The fatigue analysis of structures in general and offshore structures in particular is based on the comparison of a design stress with a specified S-N curve. This curve is usually obtained as the most conservative envelope of a constellation of dispersed points, corresponding to fatigue results obtained on different small-size and large-size models, put in a more or less clearly defined S-N coordinate system. The recent progress in fracture mechanics should allow a more rational approach to the definition both of the design stress (S) and of the fatigue life (N).
As a part of a research sponsored by the E CS C (European Coal and steel Community) the IRSID (French Steelmaker Research Institute) has tested ten X joints. In parallel, a French programme of theoretical and numerical studies was conducted at the Ecole Polytechnique in order to give a basis for the interpretation of test results, which would ensure more reliable design data for engineers.
The present paper gives an account of a part of this research. After a brief survey of the test programme, an approach to the definition of the design stress is presented in § 3 and an elementary model of the fatigue crack growth in tubular joints is proposed in § 5, which may help a more rational discussion of S-N curves.

TESTING DEVICES

Test specimens
The test specimens consisted of large size welded X-joints, represented in Fig. 1. The average values of actual dimensions of chords and braces, in particular the tube thicknesses, as well as the values of the usual non-dimensional ratios and the types of loading are given in Table 1.
The specimens were made from grade E 36 steel plate, according to AF NOR Standard. They were fabricated by a manufacturer familiar with offshore structures according to a specification which is typical of that currently used in North Sea practice. Weld size and configuration were chosen in accordance with API codes.
Wind And Wave Measurements From The First Year Of Drilling In The Baltimore Canyon
Authors: Forristall George Z. 
Published: October 2008

ABSTRACT
From April 1978 through February 1979, wind and wave measurements were made from the Western Pacesetter II while it was drilling in the Baltimore Canyon area approximately 100 miles off the coast of New Jersey. An anemometer was mounted at the top of the drilling derrick and a Wave rider buoy was moored nearby. Approximately 20 minutes of data each three hours were recorded by a microprocessor based digital recording system onto cassette tapes. The data has been processed to yield average wind speed and direction, significant wave heights, and wave spectra. Seasonal and summary statistics have been developed which show, for instance, that a significant wave height of ten feet was exceeded 8.5 percent of the year. The highest measured significant wave height during the year was 19.5 feet. These statistics should be useful in planning future operations in the area. Study of the high frequency portions of the spectra revealed that over a substantial range, it was inversely proportional to the fourth power of the frequency and directly proportional to the wind friction velocity. The classical inverse fifth power equilibrium range appeared only for frequencies substantially above that of the spectral peak. Using these observations, it was possible to produce a consistent representation of the high frequency tail of the spectrum which should be useful for developing criteria for structural fatigue studies.

INTRODUCTION
During 1978 and the early part of 1979, Shell was one of a number of operators who tested leases which had been acquired in the Baltimore Canyon area off the coast of New Jersey (Figure 1). The drilling was done from the Western Pacesetter II. Since the entire east coast of the United States is essentially a frontier area for offshore drilling, additional environmental data on the area is very useful for planning future activities. Thus, in addition to participating in the joint industry instrumentation project described by Rose et al. (1979), we decided to make wind and wave measurements from the Pacesetter II. Since most of the instrumentation needed was already on hand, it was possible to start making measurements in April, shortly after the rig moved on site.
Because of the simplicity of the instrumentation, a reasonably complete data set was collected even though the system was operated without regular service checks. The measurements add significantly to the marine climatology data base for the area, as well as providing some interesting information on the characteristics of the high frequency tail of the wave spectrum.
We begin by discussing the instrumentation and its installation on the Pacesetter II. Our operating experience with this system may help others plan similar measurement programs. The data was first processed to yield histories of the significant wave height and wind speed and direction. From these histories, we calculated seasonal and summary exceedance statistics.
Kinematics Of Deep Water Breaking Waves
Authors: Kjeldsen Søren P. , Vinje Tor P. , Myrhaug Dag P. , Brdvig Per P. 
Published: October 2008

ABSTRACT
Little is known about wave forces caused by extreme breaking waves in deep water. This study presents certain results from simulation of the kinematics of plunging breakers in deep water obtained both from carefully controlled laboratory experiments and from numerical simulation. In the experiments extreme waves are generated in three ways:The dispersion properties of gravity waves are used to generate a transient situation in which the energy of the individual waves in a wave train concentrates towards a specified point in time and space, resulting in one extreme wave;Very steep Stokes waves of finite amplitude are forced to break at a selected point in deep water due to superposition of a subharmonic disturbance;Very steep Stokes waves are forced to break at a selected point due to superposition of' a superharmonic disturbance.
In the numerical model, the development of the (breaking) wave profile, the particle velocities and the accelerations within the wave are simulated. We exact free-surface conditions. are satisfied, and good results are achieved up to the point where the overhanging crest hits the wave front.
Comparison of the plunging breakers generated in the wave flume and calculated numerically, shows good agreement with respect to the wave geometry. The measured and calculated velocities also agree well at depths larger than approximately one wave amplitude below the mean water level. In the wave crest near the plunging jet, the measured velocities are, however, 1.5 times as large as the calculated velocities. This may be due to the difference in the method of generating the plunging breakers in the two cases.
Experiments so far have now confirmed that transient, near breaking and breaking waves attain velocities up to 2.8 times the first order phase velocity.
The results may be applied to the operation and evaluation of stability of ships under severe sea conditions. Further, they provide the basis for the estimation of wave drag and inertia forces from extreme breaking waves in deep water with many applications for the design and safety of offshore structures.

INTRODUCTION
In order to evaluate safety at sea, a basic need is a prediction of the characteristics of extreme sea states. There is an extensive literature on the subject of the' mysterious disappearances of ships, both large and small. A high percentage of these mysteries can be solved by even a cursory study of so-called "freak waves" (a freak being "capricious change"), which are more correctly termed episodic waves. By definition an episode is a recurring event, and so it is with huge waves on the continental shelves. Episodic waves occur in virtually all such areas during certain predictable times of the year. The origin of episodic waves is not fully understood. It is believed that a shoaling mechanism, unique to a certain geographic location as well as a particular random phase relationship between waves, can account for the phenomenon.
Field Tests Of Adeep Ocean Cable Burial Concept
Authors: Rockwell Phil K. , Engel John H. , Piercy William B. 
Published: October 2008

ABSTRACT
Bottom fishing equipment routinely damage or break important Navy oceanographic cables resulting in substantial repair costs and unacceptable interruptions. The Civil Engineering laboratory (CEL), sponsored by the Naval Facilities Engineering Command (NAVFACENGCOM has developed and validated an engineering concept for a Deep Ocean Cable Burial (DOCB) system. The DOCB system provides an effective and reliable means of burying cables 3 ft deep in ocean sediments, at speeds greater than 1 knot, to water depths of 6,000 ft.
The DOCB system concept is a remotely controlled machine which under runs and buries existing (previously laid) cables. It is powered and controlled from a surface ship via an electro-mechanical umbilical cable. The machine is self-propelled by ducted thrusters and supported on water lubricated skids. The excavation system comprises an orbital vibrating plowshare and a vertical water jet. This paper presents the results of full scale field tests at CEL on the excavation and skid systems.
Full scale field testing of individual components as shown that a 70% reduction in drawbar force was achieved by applying an elliptical orbital vibration. It was also shown that the vibration feature would split or push aside buried rocks which would have stalled a conventional stationary plow.
The water jet tests demonstrated that a 2-1/2" nozzle cuts 36" deep in 1-2 psi of clay at a nozzle pressure of 75 psi and flow of 1200 gpm. Also tests with the skid system showed that forcing a layer of water between the skid and soil reduced the skid/soil drag by 50% in both sand and clay.

INTRODUCTION
Oceanographic cables laid on the seafloor have proved to be vulnerable to damage and ensuing failure from the otter boards of bottom fishing trawlers. The Civil Engineering laboratory, sponsored by the Naval Facilities Engineering Command initiated a development effort to synthesize a concept for a system to effectively bury the cables 3 feet deep in the seafloor to ocean depths of 6000 feet. The Deep Ocean Cable Burial (DOCB) concept (Figure 1) comprises ducted thrusters for propulsion, water lubricated skids, and two excavation means - a vertically impinging water jet followed by an orbitally vibrating plowshare, as well as a variety of other supportive subsystems.
Of all the subsystems which are required for the DOCB system, only the orbital vibratory plow, the vertical water jet, and the water lubricated skids had not been proven in situations similar to those that would be encountered during a cable burial operation.
Vibratory plowing as a means to create a trench for burying cables was selected as one of the primary excavation subsystem candidates during the DOCB concept development.
Offshore Crane Dynamics
Authors: Clarkson John A. , Kenny Francis M. 
Published: October 2008

ABSTRACT
The environments in which offshore cranes operate generate a number of factors which determine that the loadings on the structure are essentially dynamic in nature and not static as has been commonly used in design in the past. This paper presents the nonlinear equations of dynamic equilibrium and a method of solving these equations. From the theory developed a typical crane is analysed and the general trends of behaviour are discussed.

INTRODUCTION
The development of the offshore industry in the North Sea originally relied heavily upon their American counterparts for the supply of the relevant technology. However, experience rapidly showed that the operating conditions in the North Sea were significantly more severe for most of the year than existed in the Gulf of Mexico or on the Californian coast. Consequently the level of technology required to overcome many of the problems still had to be developed as the problem areas became identified. One of the very significant areas in which the environmental demands exceeded the then current design capability was in the design and operation of the offshore cranes.
The platform cranes are a vital link in the operation of the platform, not only during the fabrication and drilling stages but also during the production phase. The financial penalities which might be incurred by the operator due to any shortcomings of the cranage facilities can be enormous.
The crane structures which were originally used in the North Sea were derivatives of land based cranes and were drastreally under-designed for the duties they were expected to perform. These shortcomings were manifested by a number of assorted structural failures which resulted in the cranes being inoperable for extended periods and also led to the loss of many lives of crane drivers. Until January 1979 there were 10 fatalities in the North Sea which were directly attributable to crane operations and failures. This number of fatalities was second only to the 19 diving fatalities, an occupation which most people consider to be many times more dangerous than crane driving.
The outcome of these failures was a derating of the crane duties to levels which were significantly below those originally specified. The type of global derating carried out still indicated a lack of appreciation of the exact nature of the root cause of the problem. This statement is supported by the fact that failures still continued to occur in crane structures.
A significant number of crane structures operating in the North Sea were designed upon the principles of static structural analysis. This type of design philosophy has shown an inadequate appreciation of the loading conditions which these structures are subjected to during their operating lives. Unlike land based cranes where the lift can be made as slowly as the driver cares, and from a stationary surface, the offshore crane driver needs to be able to lift as quickly as possible to clear the load from the deck and the deck crew.
Processing Of Pacific Ocean Manganese Nodules
Authors: Itoh Hiroshi , Okuwaki Akitsugu , Okabe Taijiro 
Published: October 2008

ABSTRACT
An acid leaching process of Pacific ocean nodules has been studied. Nodules were leached with 0.1-3.5 N sulfuric acid at 70-90°C for 2-30 hours. Kinetics of copper and nickel extraction was discussed. Nickel and cobalt were recovered from the leaching solutions with hydrogen sulfide or by the cementation under pH control using ferromanganese and iron. Nickel was successfully separated from cobalt by solvent extraction with LIX 64 N extracting system adding a small amount of sodium sulfite.

INTRODUCTION
In Japan, as well as in other advanced nations, Pacific ocean nodule development is an interesting subject. In Japan, consumption of copper, nickel and cobalt has a large share in the world, and depends almost on the foreign resources. In future, Pacific ocean nodules will be major resources of the metals for Japan.
Since 1970, the basic and field experiments of the continuous line bucket mining system proposed by Masuda, have been made mainly in National Research Institute for Pollution and Resources of Japan (NRIPR). Japanese Manganese Nodule Develop Co. and Deep Ocean Mining Co. have been established for nodule mining in Japan. The Deep Ocean Mineral Association of Japan (DOMA) constructed the Hakurei Maru, a vessel for the cruise of nodule research. Japanese several company?s are joining in such international consortia of nodule development as Kennecott Joint Venture, Ocean Management Inc. and Ocean Mining Associates. The metallurgical research of Pacific ocean nodules, in Japan, has been conducted by Tohoku University, Fukushima Technical College, Yamaguchi University, NRIPR and so on.
As far as the metallurgical processing of nodules, hydrometallurgical process is generally believed to be more profitable than pyrometallurgical process. However, each consortium has selected a different process. Kennecott Joint Venture proposed an ammonia leaching process (Cuprion process). l Ocean Mining Associates selected a hydrochloric acid leaching process. 2 Ocean Management Inc. preferred a pyrometallurgical process. 3
It is preferable, especially for Japan, that the metal concentrates or metal products are made from nodules in a floating plant (a process plant on floating structures) at the sea-area where they are being mined, or on a floating barge at an island's coast near the nodule area, mainly to save transportation cost. In the first step of nodule development, metal sulfide concentrates Or cemented metals should be commercially produced in the floating plant and fed into an operating smelter.
Several hydrometallurgical processes for manganese nodules were evaluated by the present authors and reported in the Japanese literatures. 4–15 Processing at sea on a floating or sea-moored barge seems to provide several advantages, but a simple process is required for easy operation and maintenance.
A sulfuric acid leaching process, operated at temperature below 100°C in 2-3 N acid concentration, may be well suited to these requirements.
Loads And Motions Of An Aritculated Loading Platform With Moored Tanker
Authors: Naess Arvid 
Published: October 2008

ABSTRACT
The paper highlights the contents of a report containing the results of extensive model tests of an articulated loading platform (alp) both with and without a tanker moored to it. These tests were performed under wind, wave and current conditions and were done at a scale of 1:70. The alp model was of a tubular structure type (see Fig. 1), and its full scale counterpart was meant to operate at a depth of about 150 metres. The scale model of the tanker corresponded to a 150.000 dwt tanker. In our paper we shall present response amplitude curves for forces and moments along the alp column, together with the hawser tension. The motion responses of the system will also be discussed. A hydrodynamic damping coefficient for surge motion of the alp-tanker system is also given. We shall finally discuss some scale effects, especially vortex shedding from the alp, which is more pronounced in model scale than in full scale.

1. INTRODUCTION
In recent years the single point mooring offshore loading terminal has seen an increasing application in the exploitation of North Sea oil fields. Parallel with this, the developing of computational methods for predicting motion and load responses of this type of marine structures has become necessary. And the number of papers published on these matters over the last few years, clearly reflects the increasing activity in this field. It is, however, a fact that most of the experimental work carried out on particular designs are done on commission and therefore confidential. A consequence of this is that very little experimental data are accessible to research workers outside the companies who own these data.
At the Ship and Ocean Laboratory (SOL) in Trondheim, we have on commission carried out several extensive model testing programmes of single point mooring loading terminals. But as the experimental data from these tests were the property of the commissioning companies, we have not previously had any opportunity to publish any of these data. We are, however, now in the fortunate position to be able to publish the complete test results from rather extensive model tests of a single point mooring articulated loading platform (spm-alp) designed to operate out in the North Sea. And in the present paper we shall give some of the most important results from these model tests.
The test programme was carried out in Wave Tank no. 1 at SOL. It has dimensions 175m × 10.5m × 5.8 m (length × breadth × depth). The complete programme consisted of 31 different tests both with and without a tanker moored to the spm-alp and under various environmental conditions.
During the tests all motions of the alp and tanker were measured and recorded, and the alp was equipped with specially designed transducers at four different locations along the structure to allow measurements of shear forces and bending moments.