bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wave Direction Measurement By a Single Wave Follower Buoy
Authors: Middleton F.H. , LeBlanc L.R. , Sternberger W.I. 
Published: October 2008

ABSTRACT
This paper describes a system for measuring the direction of ocean wave propagation, as well as wave height and period. The system employs a conventional wave-follower buoy, modified so as to provide compass, pitch, and roll signals in addition to the vertical component of buoy acceleration. The modifications are indicated in the paper, and the buoy was used in rough water conditions in Narragansett Bay for a test. The pitch, roll, compass, and heave acceleration signals were all processed on the computer in the laboratory to provide a variety of results. This test condition was ideal in that the wind and wave conditions were changing steadily throughout the data recording process. The results presented in the paper include the wave height power spectral density, a polar tilt histogram for the buoy motion, and a family of polar plots of the average tilt angle in each 5° sector of azimuth of the buoy pitch/roll.

INTRODUCTION
This paper is the third in a series of OTC papers on the subject of the continuous development of wave-follower buoys, starting in 1975. The first paper was OTC 2424 in 1975 on the mathematical analysis of wave data making optimum use of fast computer techniques. The next paper was OTC 2597 in 1976 and it was devoted to ways to handle the problem of spectral compensation of acceleration data from a buoy to produce a true wave height power spectral density (PSD). This last paper also was condensed and published in the June 1977 issue of the Journal of Petroleum technology. It is the purpose of the present paper to extend this buoy development history to include not only the PSD of an open-sea wave field, but the direction of propagation of the dominant wave mode (or modes) that are present.
In many important ocean operations, either on the open sea or near shore, the direction of propagation is often of more importance than the significant wave height, or the power spectrum. This clearly is the case, for instance, for storm waves striking a beach, a harbor channel, a breakwater, or any sort of offshore structure. Up to the present time, anyone needing wave-incidence direction data has been forced to deploy complex, complicated, and expensive spatially distributed arrays of wave measurement devices. Using wave staffs on a structure requires spatial separation on the order of the wave length of interest in order to obtain reliable results.
The buoy used in this study was a Model WF-100 wave Follower Buoy manufactured by Coastal Data Service, Inc. (licensed to Hydro Products, San Diego) on loan to the U. of Rhode Island for purposes of the present development. It was necessary for Coastal Data Service to modify their standard buoy, by the addition of tilt and compass sensors, to make it possible to measure propagation directions. Some internal modifications were required to provide space for the necessary additional sensors.
Trigone Jack-Up Drilling Rig
Authors: Laplante Gilbert , Clauw Rene 
Published: October 2008

ABSTRACT
The jack-up drilling rigs TRIGONE, built according to the North Sea regulations and the DNV classification requirements, for 350-ft water depth (i.e., for a wave height of 65 ft and a wind velocity of 100 mph), are the largest self-elevating units operating in the world. Their design has been developed bearing in mind their possible use as an early production platform. The rig is equipped with a skidding system allowing a drilling area of 21 × 21 in.
The legs have a length of 507 ft. They are built from cast joints, tubular bracings, chords, and racks. All steels are high tensile steel with impact notch tests at minus 40°C. Test programs for materials and welds have been developed especially by the Det Norske Veritas in collaboration with the builder. Welding procedures have been established by same under DNV survey.
Elevating units (gear and pinions) electrically driven, have a maximum holding power of two times the elevating power. The power of the jacking system permits elevation and holding in drilling conditions 2500 metric tons of variable loads and holding under storm condition more than 2000 metric tons.

INTRODUCTION
The two jack-up TRIGONE have been built by CYEM in its Dunkirk yard for the Norwegian ship owner DYVI OFFSHORE Co. These rigs are the first ones especially designed to work in 350-ft water depth in the North Sea. Design and particular studies of equipment installation have been approved by the Det Norske Veritas and Norwegian regulatories bodies. Construction in shop and erection at the yard also have been surveyed and approved by the same authorities.
These rigs have obtained DNV class notation I A I self-elevating unit, all certificates from the Norwegian authorities (Maritime Directorate), and also obtained the certificate of fitness for operations in U.K. waters.

GENERAL DESCRIPTION (Fig. 1)
The platform structure consists of a triangular hull supported by three legs made of triangulated steel bracings. In drilling position, the legs stand on spud tanks on the bottom of the sea.
The hull makes the buoyancy element during towing conditions.
Legs are located at the three angles of the hull and are used before drilling operation to elevate the whole hull.
The living quarters are in above decks in one structure, mounted on the main deck just aft of the forward leg well.
Hull (Fig. 2) - The hull is of triangular barge form. The primary structural system is of longitudinal and transverse bulkheads. The hull is surrounded with double bottoms (under and on the side of the rig). The machinery spaces are made of 13 technical rooms located just under the main deck.

Spud Tanks and Legs (Fig. 3)
Each leg consists of a hexagonal bearing tank (spud tank) with a conical point at the bottom, surmounted by a truss triangular in cross-section. The truss-type leg structure has three corner members consisting of two continuous racks joined by a plate forming the diameter of a circle.
Convergent Plate Margins for Field Geologists
Authors: Karig D.E. 
Published: October 2008

ABSTRACT
The variability and complexity of active plate margins require that the identification of units of previously active margins in orogenic belts be done with care and sophistication. Tectonostratigraphic units from active margins vary not only as sedimentation and plate kinematic parameters change spatially, but also temporally, as these parameters evolve. Deposits from the trench, lower slope basins and upper slope or forearc basins may be distinguished using the distinctive structural styles, sedimentation pat terms, and lithologic content observed within each unit. The relative positions and characteristics among the units are equally important criteria.

INTRODUCTION
Recent geological and geophysical investigations, interpreted in the framework of plate tectonics, have produced a general geological model of convergent plate margins. Nevertheless, one of the most important objectives, that of identifying various elements of a previously active margin within an orogenic belt, remains elusive. The field geologist, if he is to interpret the evolution of the complexly deformed mountain belts formed by plate convergence, must be able to deduce the original tectonic settings of the various tectonostratigraphic units which are now deranged by younger overprinting and by large-displacement faulting.
The purpose of this paper is to review diagonistic characteristics of the various packages of rocks produced within a convergent plate margin with which these units might be identified after their morphology is destroyed. An admonition is immediately required. There is no typical arc system, but rather a broad spectrum of responses arising from a single basic process. As a result, in this setting, perhaps more than in any other, identification using simple criteria can lead to serious error. Only a comprehensive integration of data and an adequate knowledge of arc behavior is likely to produce the correct interpretation.
Convergent plate margins range from oceanic island arcs involving very little sediment to continental margin arcs which often have several kilometers of sediment on the descending plate. These differences are reflected in wide variations in size, shape, and lithologic content of units [Fig. 1]. Not only do convergent margins vary spatially, but also temporally as sedimentation and kinematic parameters change. To compound the difficulty, morpho tectonic units are the basis for subdivision in active arc systems whereas in orogenic belts, only lithologic structural entities (tectonostratigraphic units) remain. These may differ because a given tectonostratigraphic unit may be involved in several different morphotectonic units the arc evolves. For example, a block of trench turbidite rapidly becomes part of the lower trench slope. Later this same block of rock may become part of the basement beneath a forearc basin or even later may become part of the frontal arc, but when mapped in the field as a melange, it cannot be used to locate that frontal arc until temporally correlative information on other arc units is available.
In Situ Fatigue Analysis Of A Tubular Joint: Hydrodynamic And Mechanical Aspects
Authors: Barnoiun B. , Thebault J. 
Published: October 2008

ABSTRACT
A very simple experimental structure has been designed to perform fatigue-corrosion analysis of tubular joints. The methodology is described, together with the results of the static tests needed to interpret the measured data. A complete set of S.C.F. values for every possible situation has been determined. Besides, the opportunity was seized to test the methods available for foreseeing vortex induced vibrations and to initiate a study of the behaviour of the pile submitted to hydrodynamic forces. The procedure and some results are indicated.

INTRODUCTION
Offshore oil development is built upon the capacity of present technology to erect production platforms in large water depths and to assess their ability to withstand long term action of the environment.
Calculation procedures of the jacket type structures are now well established. Nevertheless, some uncertainties remain about the input of these models, and particularly about the corrosion fatigue strength of the tubular joints that form the nodes of the lattice-work, and through which structural loads are conveyed. Moreover, there are still large gaps in the knowledge of the fluid action on cylindrical obstacles which constitute the basic element of this lattice, specially in the case where the dynamic properties of the structure allow for large relative displacements.
The experiment described hereafter is aimed at a better understanding of these problems, typical of the real environment complex action.

DESIGN OF THE STRUCTURE "S.E.D.A.T.I.S."
The system consists in a tubular joint clamped to the seabed through a heavy concrete base (12 metric Tons). The brace of this T. joint is extended by a 14 m. long vertical pipe. A detailed diagram of the experiment may be found on Fig. 1.
This very simple assembly, named SEDATIS (Systeme d'Essais Dynamiques d'Assemblages Tubulaires In-Situ), offers at least two valuable testing opportunities :from an hydrodynamic point of view:The pile is loaded as well by currents (as high as 2 knots at spring tides) as by waves, the height of which may reach 2 meters in Winter. Besides, the immersed length of the vertical part varies with the tidal elevation from 8 to 15 m. As a result, we have been faced with a great variety - and complexity - of loading cases. The Reynolds Number has a maximum value of about 3.105.from a mechanical point of view:The weld fillet is placed in a representative corrosive environment, and submitted to a true nonstationnary wide-band random loading.Besides, the overall loading spectrum has proved to have a mean frequency high enough to ensure a time compression of 10 to 1 (Le. 108 cycles in less than two years).
The design conditions were estimated as follows:
(Available in full paper)
and the pile has been designed using Morison's formula. The inertia terms are negligible in the design conditions for an outer diameter of: D = 18 cm.
A Proposal For The Permanent Disposal Of Nuclear And Other Toxic Wastes Utilizing Offshore Technology
Authors: Krutenat Robert A. 
Published: October 2008

ABSTRACT
This paper is a proposal to apply the capabilities of offshore technology to a new area-nuclear waste disposal. Permanent disposal is accomplished by placing the wastes in boreholes drilled, for that purpose, in the basaltic basement rock of the oceanic plates. The boreholes are drilled at the very edge of the subduction zone allowing the descending tectonic plate to carry the wastes into the center of the earth. Sufficient distance of subducting oceanic plate exists west of Washington and Oregon and south of the Aleutian chain, to accommodate the waste output of the United States for several hundred years (assume boreholes 0.3m diameter, 1,000m deep on 50m centers). Waste disposal in the ocean is not new. The unique aspect of this proposal is the location of the boreholes in the subducting basement rock allowing the descending plate to carry the waste into the molten core of the earth. Several hardware configurations are suggested, with appropriate sketches, to implement the proposal. The annual cost for disposal using this method is estimated to be 0.072mils/kWh (nuclear) or $3.74 million per 1,000 MW "standard" reactor.

INTRODUCTION
The disposal of radioactive wastes from nuclear reactors and other activities of atomic energy research, is a problem facing world society. This problem arises from the long half-life of the radioactive waste products and the toxicity of the chemical compounds in which the radioactive material is found. The magnitude of the problem can be expressed as follows: About 2.23m3 of solid waste are produced by a "standard" 1,000 MW reactor each year.l Five hundred such reactors would produce approximately 1,115m3 of solid waste each year.
"Plutonium 239 has a half-life of nearly 25,000 years and 10 half-lives are required to cut the radioactivity by a factor of 1,000. Thus the buried wastes must be kept out of the biosphere for 250,000 years."2 The problem is: Where can the material be located so that it is impossible for it to find its way back into the environment?
Early in 1960, geophysicists realized that the crust of the earth was formed of large solid plates moving relative to each other.3 These large basaltic plates are formed at ocean ridges and return to the center of the earth at places known as "subduction" zones.4 The plates re-enter the earth at about 5 to 6 centimeters per year.5 Material contained in the basement rock, as well as most surface sediment, is being constantly returned to the center of the earth.6.
The solution to the problem is: Place the waste material in the basement rock of-an-oceanic plate at the edge of its subduction zone and allow the crustal movement to carry the waste to the of the earth. About 58 million years are required for a one-way trip.7.
Deepwater Pipelaying Method With A New Welding Technique And J-Curved Pipestring
Authors: Koenig D. , Muesch H. 
Published: October 2008

ABSTRACT
Extensive studies have shown that the J-method of offshore pipelaying can substantially increase the water depth capability for 20 inch pipe to about 3, 000 m (9,850 ft) or for 40 inch pipe to 1,200 m (3,950 ft). This achievement is not presently possible with conventional S-method pipelaying. This method was rendered feasible by the development of a fast, new flash butt welding technique.
The entire J-pipe system is described and the technical practicability and potentialities for pipelaying are reported.
Extensive welding tests have been performed and more are in progress. The tests have shown that the improved flash butt welding technique can produce quality welds meeting the requirements of offshore laying. The prototype welding machine is almost complete and further test series are scheduled.

INTRODUCTION
In the first half of the seventies there has been a substantial increase in efforts toward finding technically and economically acceptable solutions for deep water pipelaying.
On one hand there are drilling activities in deeper and deeper waters. In 1974/75 drillers reached water depths of 600 to 700 m (2,000 to 2,300 ft). Pipelaying techniques are still relatively undeveloped for those water depths. In spite of decreased drilling activities in deep water, development is continuing. The 2,000 m (6,500ft) mark is forthcoming.
On the other hand the problem of transporting oil and gas across deepwater areas exists. Best examples are pipelines for the Norwegian Trench and the Mediterranian Sea. The utilization of that gas found offshore or onshore - without a pipeline is possible only by shipping the gas to consumers in a processed condition, as methanol, LNG, etc.
In 1975 a group of German companies commenced a deepwater pipelaying research and development programme. Many concepts for deepwater pipelining were assembled and evaluated. Special attention was paid to economic aspects, to the state of art, to experience with various pipelay techniques, and to the availability of essential technology in consideration of risks and time for research and development.
The most promising method J-pipelaying with flash butt welding - was singled out and further developed. This paper describes results from this development programme.

ARGUMENTS FOR J-CURVED PIPESTRING LAYING
Offshore pipelaying methods differ in the procedure for lowering the pipestring and in the method of connecting new sections. If the pipeline is lowered from the surface, the suspended pipe span forms a J-curve or an S-curve. If a pipestring is constructed by the bottom tow method, there is no such curve. The last method requires an on-bottom connection, the first and second mentioned methods can be performed by (1) an on-bottom, (2) a floating (i. e. between bottom and surface) or (3) a surface connection Many technical limits of the pipelay methods refer to these aspects. Other limits are economic ones.
Determination Of The Period Range Associated To The Design Wave
Authors: Arhan M.F. , Cavanie A.G. , Ezraty R.S. 
Published: October 2008

ABSTRACT

Description of the paper
This paper presents two new methods of determination of the range of periods associated to the design wave. The first is based on the analysis of the extreme wave for each storm recorded, the second on an adaptation of our individual wave height-wave period joint distribution previously published. Data used in this work came from U.K.O.O.A. waverider recordings in the northern North Sea for values Of H1/3 greater than 6 m. A total of 340 hours of sea surface recordings collected from 21 major storms at point Stevenson over a three years period were analysed by the zero upcrossing method.

Applications
The methods developed are adapted to determine the range of periods to be associated to a given design wave height, once given sea state data over a reasonable period of time.

Results, observations, conclusions
In view of the nature of severe storms, a strong statistical relationship is observed between H1/3 and Tz.u.c at the storm peaks. For a given H 1/3, variations in Tz.u.c from one storm to another and variations in periods of individual waves for a given height in a given sea state both contribute significantly to the width of the period range for the design wave. Continuous zero upcrossing analysis over each storm gives the highest waves encountered from which can be determine a 14 to 17 second range for the period of a 30 m design wave. When an appropriate choice of the spectral width parameter, evaluated by comparison with data, is used in the theoretical individual wave height-wave period joint distribution a probability distribution for the period of the design wave is obtained. This second method, which depends only on mean sea state parameters (H 1/3, Tz.u.c) leads to results quite similar to those of the first method.

INTRODUCTION
The period to be associated to the design wave (fifty or one hundred year wave height) can be fixed only within a certain period band, because within a given sea state there is a continuous distribution of periods for a given height and because different meteorological conditions will lead to sea states having similar extreme wave heights but different associated periods. At the present time, in the North Sea, for a design wave close to 30 m in height, a range of periods between 12 and 18 seconds is advocated. Within the climatology working group of A.R.A.E. (Association de Recherche Action des Elements) we have sought for methods in order to determine this range of periods objectively and have applied them to data concerning the most severe storms at point Stevenson (61°20' N, 0°0' E), North East of the Shetlands over a three winter period (1973-1976). We are indebted to the U.K.O. O.A. (United Kingdom Offshore Operators Association) which kindly placed this data at our disposal for this study.
New Underwater Threshold Of The 1980S, Demands New Answers From Underwater Contractors
Authors: Galerne Andre 
Published: October 2008

ABSTRACT
This discussion analyzes present and projected trends in underwater contracting, as related to exploratory drilling in constantly deeper waters in the quest for new fossile fuel sources. Its primary focus is on the problems facing diving contractors who must be careful in their efforts to survive and prosper in an industry that is expanding in all directions underwater, while new sub-sea technology has tended, as of late, to remain moot.
Three basic modes of underwater diving service - hyperbaric; monobaric; and remote control - are examined. Specifically, this analysis is aimed at the problems associated with supporting exploratory drilling in waters beyond 1500 feet deep, the depth at which anchors have to be abandoned in favor of dynamically positioned vessels.
A threshold has been reached comparable to the 200 foot watershed met in the early 1960s, which was overcome by the introduction of mixed gas bounce dives to 600 feet for short term projects, and saturation diving practices which are today used on long term projects to depths of over 1000 feet. Vital work beyond 1200 to 1500 feet, the author contends, will have to be carried out either by tethered unmanned vehicles compatibly designed to work on deep sea structures; by manned monobaric diving suits or bells; or more likely, by free swimming submersibles.
An analysis of present methods of under water intervention is given, followed by an explanation of the role free swimming submersibles will probably play in the future as an adjunct to deep sea drilling techniques. It concludes that manned submersibles will in effect be safer, with far greater operational capabilities, than either monobaric diving suits or tethered unmanned vehicles. It also notes that the problems of safety in deep water offshore operations may be the determining factor in resolving which options will be selected by oil companies, as governments, under whose jurisdiction they operate, move to ensure that diving accidents are kept to a minimum.

HISTORY
Two decades ago man's ingress into the underwater environment, although centuries old, was still in its infancy. Working dives to depths beyond 200 feet were rare and carried out commercially only on compressed air, mixed gas still being the domain of the united States Navy. Despite the fact the deepest known depths of the oceans had been plumbed by the bathyscaphe Trieste, mid and shallow water submersibles were just beginning to appear and none were being built for commercial application. When in 1961 a young Swiss mathematician, Hannes Keller, irrefutably demonstrated by going to a 1000 feet (in a hyperbaric chamber) that the depth barrier for man breathing an artificial atmosphere was far beyond what many experts deemed the absolute limit, there were still those who claimed manned intervention to such depths would never be practical, nor would there be justifiable application.