bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Wave CI imatology for U.S. Coastal Waters
Authors: Thompson Edward F. , Harris D. Lee 
Published: October 2008

ABSTRACT
Over the past 20 years, the Coastal Engineering Research Center has operated wave gages along the Atlantic, Pacific, and Gulf coasts of the U. S. Cumulative wave height distribution functions for ten gage locations have been studied in the format of the exponential distribution. One complete year of data, at six observations per day, appears to give a reliable wave height distribution up to the 1% level of occurrence. Wave data from shipboard weather reports have been compared to wave gage data and found to be of some use in describing long term summaries of coastal wave height conditions.

INTRODUCTION
Ocean wave sensors, operating in the harsh environment of coastal waters, record a complex phenomenon which is not easily interpreted. The simplest analysis approach is to characterize wave conditions from each record by a single wave height and wave period. The Coastal Engineering Research Center (CERC) has accumulated a body of wave data of this type determined from pen and ink records. These data, despite their limitations, contain useful wave climatology information. Reports from shipboard observers provide a body of less precise wave information for offshore waters.

WAVE GAGE DATA
Since 1948, CERC has been operating wave gages at various locations along the coasts of the United States (Figure 1). Gages have been placed and maintained in water of depths from 3 meters (10 feet) to 30 meters (100 feet) below Mean Sea Level, but most data have been taken in water from 3 meters to 8 meters (25 feet) deep. For each gage location, data have been recorded over a period of time ranging from a few months to over 15 years.
Most wave data were obtained with the step resistance type gage (a staff gage) described by Williams (1969). For many years the step resistance gage was the only type of surface wave gage which operated with consistency in the ocean environment. Recently other reliable surface gages have become available. One type, which interferes less than the step gage with the waves, is the continuous wire gage. A comparison of objective wave height estimates (Esteva and Harris, 1970) based on simultaneous records from these two gage types has shown that estimates of significant wave height from the step gage records are on the order of a foot or 20% higher than the estimates obtained from the continuous wire gage records (Figure 2, from Harris, 1972). Wave height estimates from pressure gage records reported by Esteva and Harris, corrected to surface conditions, agree well with height estimates from the continuous wire gage.
Pen and ink wave records, usually 7 minutes long, were recorded every 4 hours at gage sites until May, 1966; since then, data from some gages have been transmitted directly to CERC via telephone line. These data are recorded at the CERC laboratory in the form of pen and ink records and, in digital form, on magnetic tape. In July, 1971, most gage stations were modified to obtain pen and ink records every 6 hours, to coincide with synoptic weather charts.
From removing to using multiples
Authors: Berkhout A.J. , Verschuur D.J. 
Published: October 2008

Abstract
In the last decade much progress has been made to remove multiples from seismic data. So far, multiples have been considered as noise and, therefore, after the removal process multiples are thrown away. In this paper, we will show that multiple reflections contain a wealth of information that should be used in seismic imaging.

Introduction
In the history of multiple removal, algorithms have been based on two differentiating properties: moveout and predictability. If primaries and multiples show different moveout behavior, algorithms are available that allow separation of primaries and multiples in a transform domain. A weak point of moveout algorithms is that they become less effective in the situation of complex wavefields (think of nonhyperbolic wavefronts), or when the moveout of primaries and multiples are alike (e.g. deep data).
Predictability has always been important in multiple removal. In the early days of seismic processing (the 1960's), single trace statistical prediction was very successful (Robinson, 1957). In the early 1980â??s prediction-error filtering has been given a wave theoretical base, providing a unified theory for surface-related and internal multiples (Berkhout, 1982). It has increased the effectiveness of multi-channel prediction-error filtering significantly (Verschuur, 1991). Nowadays, multiple removal algorithms are to a large extend presented by wave theory based multi-channel prediction-error filters.
Recently, a third direction in the theory of multiple removal was proposed that is inspired by the double focusing process as it occurs in seismic migration (Berkhout, 1997). The new theory is based on the so-called focal transform. Forward focal transformation transforms primary energy into its focal point around zero time. After an imaging step, the result is input to the inverse focal transform leading to the desired multiple-free output. First results indicate that combined prediction and imaging may lead to the next paradigm shift in multiple removal.
Figure 1: a) Feedback model for primary reflections (m &gt; 0) and surface-related multiples, the multiple-generating boundary being given by z0=z0(x,y) and the downward reflection operators of this boundary being represented by the columns of the matrix R^(z0). b) One basic element of the weighted convolution process for surface-related multiples, visualized in terms of simple raypaths (m &gt; 0). (Available in full paper)

Removal of surface-related multiples, the prediction approach
The so-called feedback model shows that prediction of multiples requires a weighted convolution process with the primary response (Berkhout, 1982). If an estimate of the primary response is available, the convolution process becomes iterative. The convergence turns out to be fast, even if one starts with the total dataset as primary estimate (Verschuur and Berkhout, 1997). Let us reconsider the feedback model, using the detail-hiding operator notation (see also Figure 1)
Factors Affecting the Measurement of Axial Stiffness of Polyester Deepwater Mooring Rope Under Sinusoidal Loading
Authors: Casey N. F. , Banfield S. J. 
Published: October 2008

Abstract
This paper presents laboratory testing results to explore the experimental and fundamental dynamic axial stiffness behaviour of polyester ropes for deepwater mooring systems. Effects of mean load, load range, load or stroke control, extensometer versus crosshead, peak trough versus linear regression, cyclic period and scale effect (60 to 600kN) have been studied.
Understanding the axial stiffness behaviour is essential for calculating peak line tension and platform offset for riser excursion and fatigue life. Also, the effect of bedding-in of the rope structure, which increases stiffness, is required to establish the test matrix for certification.
A thorough review of the methods of data collection, interpretation of data and calculation of stiffness has been conducted. For those methods reviewed, no significant differences in stiffness have been found except for crosshead, which tends to be higher than measured directly on the rope between splices.
The effect of cyclic period and scale effect upon dynamic axial stiffness has shown to be insignificant and for dynamic mooring system response can be ignored, which reinforces previous work. For drift and longer term effects, the effect is very small and needs to be considered whether any allowance is needed. The effect of bedding-in on axial stiffness has shown that to reach peak axial stiffness, very large numbers of cycles are required. Typically, however, around 80-90% of the peak axial stiffness can be reached within several hundred cycles. For full-scale certification, the costs and time of large numbers cycles maybe prohibitive, so a technique has been suggested for conducting these tests on scale samples since there is no scale effect of stiffness.
These results will add to the knowledge base for understanding axial stiffness behaviour from testing, data collection, stiffness calculation method and mooring/riser system design. It will also provide valuable data for the future rewrite of API 2SM, to ensure that certification test methods collect the appropriate axial stiffness data for polyester ropes. The information will also be of use to the regulatory bodies.

Introduction
The main purpose of the work presented in this paper was to investigate the experimental factors that can influence the measurement of dynamic axial stiffness of polyester rope when subjected to sinusoidal loading.
The factors addressed in this paper are:
- Testing medium (air or water).
- Constants and variables, in the calculation of dynamic axial stiffness.
- Linear regression stiffness versus peak trough stiffness.
- Extensometer derived stiffness v crosshead based stiffness.
- Machine load control versus stroke control.
- Effect of cyclic period upon axial stiffness.
- Load History.
- 60 kN sub-rope to 600 kN rope stiffness scaling.
A 60 kN sub-rope together with 600 and 2,500 kN ropes of parallel strand construction (PSC) were tested during this investigation.
Deep Water Navigation With an Inertial System
Authors: Mateker Emil J. , Ott Leo E. , Shave David G. 
Published: October 2008

Abstract
Integrated satellite-navigation systems have been employed extensively for positioning marine geophysical surveys in the past three years. Since most exploration has been in relatively shallow water, dead-reckoning with doppler sonar velocities and gyrocompass heading reference has proven adequate. For programs in deep water, we have mechanized an inertial system to provide velocity and heading data for real-time positioning and postprocess mapping with the precision required by the geophysical industry. This is accomplished through real time software control. Inertial-platform drift is determined initially by comparing satellite fix positions with inertial coordinates. Inertial drift curves are predicted, and ship position is controlled by compensating for this drift. As drift characteristics change, drift prediction is updated. Continuous experience at sea since early December, 1971, had demonstrated that system drift can be effectively controlled. On the basis of all satellite fixes regardless of elevation angle, for operations on or near the equator, drift rates have been less than 300 m/hr. about 70% of the time, and less than 450 m/hr. about 90% of the time. Research with more sophisticated prediction methods led to software changes, introduced in October 1972 which showed some performance improvement but also demonstrated a shortcoming in the error model. Software changes, to be introduced shortly, are expected to show a 20%-30% improvement in drift rates. At higher latitudes where more good angle passes are available, system performance will be even better!

INTRODUCTION
There are a variety of radio systems available for marine navigation. However, none are able to provide continuous, world-wide navigation with the accuracy required for marine geophysical surveys. Consequently, integrated satellite navigation systems were introduced in 1969 to satisfy this need and used extensively with varying degrees of success. These systems rely upon periodic position fixes from the Navy Navigation Satellite System. Orbital data and frequency measurements are used in the position calculation (Stansell (12)). On the average, an acceptable position fix is obtained about once everyone to two hours, depending upon latitude. Since most geophysical exploration has been in relatively Shallow water (less than 100 fathoms), dead-reckoning between fixes with doppler sonar velocities and gyrocompass heading has proven adequate.
In deep water, doppler sonar performance is degraded due to an inability to track the ocean floor. Under this condition the sonartracks a return from the water mass and hence the sonar velocities are in error by the amount of any sea current. Halamandaris and Ozdes (S) proposed a solution to the problem of deep water navigation with an integrated satellite doppler-sonar system by the use of a sea-current biasing technique.
Optimal utilization of Groundbased Navigation Systems In Worldwide Deep-Sea Navigation
Authors: Sender Friedhelm 
Published: October 2008

ABSTRACT
The application of satellite-navigation is increasing rapidly. But for practical use the only presently available transit-system has still several limitations, so that conventional groundbased radionavigation systems have not lost their significance. The optimal utilisation of those systems especially in view of the cooperation with satellite-navigation will be discussed here.
Satellite-navigation is the modern technology successor of astronavigation -with increased accuracy at day and night as well as aII weather capability. The disadvantage is, that presently installed systems are using exclusively sateIIites orbiting at relatively low altitudes about the earth with an orbiting time around 90 minutes. So satellites are only sporadically "visible" to the user and since all actual orbits are about the poles satellite-fixes are available at a medium random rate of one hour with higher frequency at the polar and less at the equatorial regions. Because it takes up to 16 minutes to sample the data necessary for a fix the accuracy of the fix depends to high extend on the exact knowledge of the path of the ship during this time. So it proved obligatory to use satellite-navigation together with an additional all time navigation system to achieve high accuracy and always real time position-information. Still better results may be achieved by integrating more than two positioning systems and optimal correlation of respectively available data.
Sonar-Doppler-navigation is the most widely used system for integration with satellite-systems. It has nearly ideal characteristics in coastal shelf areas with a water depth lower than 600 - 1,000 feet. Disadvantages of Sonar-Doppler are:High installation cost for the transducers on ships' hull in drydock;
Low accuracy in deep-sea, where system switches to "water track" and sea current cannot be eliminated, apart from transients and track losses due to plankton movement and sound velocity dispersion.
In many shelf areas are fixed radio navigation aids installed, which makes Sonar-Doppler redundant. Radionavigation has at least theoretically and in deep-sea many advantages compared to-Sonar-Doppler. But its use in integration with satellite-navigation hitherto was limited. The reasons are probably:Very long range radionavigation is burdened with propagation irregularity problems;Most systems are only at daytime useable with full accuracy caused by ionospheric properties;Apparently there are not enough installations for full worldwide high accuracy coverage;For successful integration with satellite systems long range radionavigation date seems too noisy.
These problems inherent to radionavigation will be discussed in the following part.

Propagation problems of different systems
Radiowaves are normally propagating similar to the light in a straight direction. For long range radionavigation the receiver-transmitter line is vignetted by the horizon.
A Design Method For an Anchor Pile in a Mooring System
Authors: Reese Lymon C. , Beard Richard M. 
Published: October 2008

Abstract
A procedure is described for the design of a pile in soft clay to provide an anchor for a moored vessel. A method is presented for computing the angle of incidence of the anchor chain with the pile, and theories are presented for computing the behavior of the pile. The procedure can be employed to compute the dimensions of the pile and optimum positioning of the chain bracket along the pile. Example computations are presented.

Introduction
In the mooring of floating vessels at locations where the bottom consists of soft soil, ship anchors frequently do not give sufficient holding power. A possible solution to the problem is shown in Fig. 1. The scheme involves the welding of a bracket to a tubular anchor pile and the attaching of the end of the anchor chain to the bracket. A pile is then driven with a follower to the desired penetration below the ground surface. The follower is subsequently retrieved and, when tension is applied to the chain, the chain assumes a position such as that shown in the figure.
In the design of such a system the following information is normally at hand: water depth, shear strength and other properties of the soil, availability of construction equipment, tension on the anchor chain, and dimensions of the chain. The problems which are to be solved are to find the optimal length and diameter of the anchor pile, the position of the bracket along the pile, and the depth below the mudline to which the pile should be driven.
In order to obtain solutions to the above problems, one must employ methods for analyzing the behavior of a pile under lateral and axial loading and for predicting the position of the anchor chain in the soil. The following paragraphs give brief presentations of those methods and give example computations.

Behavior of a Pile Under Lateral Loading
A model of the problem to be solved for behavior under lateral loading is shown in Fig. 2. The soil in Fig. 2 is represented by a set of mechanisms. These mechanisms are used to depict a set of curves which are varying in character along the length of the pile, with respect to x, and are such that the resistance p is nonlinear with pile deflection y. The concept of p-y curves can be explained by Fig. 3.
In Fig. 3a a section is shown through a pile which has been driven into soil, with the soil stratum to be examined indicated at the depth below the ground surface x1. The earth pressure distribution around the pile after driving and prior to lateral loading is shown in Fig. 3b.
Testing of a High Seas Oil Recovery System
Authors: March Frank A. , Beach Robert L. 
Published: October 2008

ABSTRACT
A system for recovery of petroleum products from accidental offshore spills has been developed and tested. The testing has included both model testing and full-scale testing of a 60-foot long system capable of recovering oil at a rate of 2000 gallons per minute.
The tests have shown the system capable of recovering spilled oil at high efficiencies (less than ten percent water in the recovered oil) at the 2000-gpm rate under environmental conditions ranging from calm to low state 5 Seas (eight-foot significant wave height) and in currents up to three knots.
The system efficiency (percent of oil in the recovery stream) is relatively independent of oil specific gravity, viscosity, oil film thickness, wind and wave conditions, oil-water interfacial tension, surface temperature and variation in significant oil type when towed at speeds of one to three knots. As indicated, efficiencies of 90-100 percent can be expected under these conditions.
The oil recovery rate is relatively independent of wind and wave conditions, surface temperature, oil specific gravity, oil-water interfacial tension and significant oil type variation. It is not affected by viscosity except for discharge hose pressure limitations above 10,000 SSU.
The oil recovery system is air and truck transportable for rapid deployment to a remote spill location. It is completely self-contained having its own power unit, control system, and pumps. In its preferred deployment configuration it is used with oil containment booms for funneling the oil to the recovery system.
A double weir system is employed to obtain the high performance of the system. The system is operated in such a way that oil thickens in front of the primary weir and then further thickens in front of the secondary weir, where it is withdrawn. Typically, the system concentrates free slicks from a thickness of 0.1 inches or less to a depth of approximately two feet front of the secondary weir.
The testing reported upon includes both model testing and full scale testing of the system. The work reported upon was partially supported by the U. S. Coast Guard.

INTRODUCTION
Accidental oil spills on coastal and ocean waters are a matter of increasing concern. It has been recently estimated(1) that over 200,000 metric tons of oil are annually discharged into the world's waters from accidental spills. This spillage not only represents a loss of product but also represents substantial cleanup costs and potential liability. When the spillage occurs offshore in a wave environment the oil spreads fairly rapidly and cleanup becomes a major problem. Only recently have methods been developed for cleanup of oil spills in an offshore environment. This paper deals with one of those methods.
There are two major elements to any successful cleanup operation which must be carefully coordinated: containment and recovery.
Mariculture In an Artificial Upwelling System
Authors: Roels O.A. , Babb J.S. , Hamm G.L. , Haines K.C. 
Published: October 2008

ABSTRACT
We have established an experimental mariculture system on the north shore of St. Croix (U.S. Virgin Islands), using as raw material water pumped from a depth of 870m in the sea. This deep water is cold and rich in nitrate, phosphate, silicate and other dissolved nutrients necessary for plant life.
It is particularly free of human disease-producing organisms, shellfish parasites, predators, fouling organisms and man-made pollutants. Moreover, its chemical and thermal characteristics are constant. The St. Croix site was chosen because the ocean reaches a depth of 1000 meters approximately 1.6 km offshore.
The deep water is pumped into pools onshore in which blooms of diatoms are produced to feed shellfish.
To date, F1 hybrid (or racial cross) clams (Merc'en'a'ria mercenaria Linne X Mercena-r-iacarnp'echien'sis Say), the European oyster (Ostrea edulis Linne), and the bay scallop (Argopecten irradians Lamarck), have been grown to market size in the system in less than one year.
A taste panel judged the quality of the shellfish grown in the St. Croix system to be excellent.
Slow-growing shellfish are culled from the system and used to rear the spiny lobster (Panulirus argus), and the Maine lobster (Homarus americanus). Preliminary experiments with carrageenan and agar-producing seaweeds to purify the effluent from the shellfish tanks are underway.

Introduction
It is well known that deep ocean water is cold and rich in the dissolved nutrients necessary for plant life. In our experimental mariculture system on the north shore of st. Croix (U.S. Virgin Islands), water from 870 m depth in the sea is pumped into 4S,000-liter concrete pools onshore where algal blooms of 2 diatoms (Chaetoceros simplex and Bellerochea sp.) are produced as food for shellfish in a managed food chainTable 1 compares the nutrient content and other parameters of surface water in St. Croix and water from 870 m depth, pumped up through our deep-water pipeline. As is clear from Table 1, the deep water is cold and rich in nutrients: its cold temperature can be used for a wide variety of cooling applications and for sea-thermal power production by the Claude_ processin areas where the temperature differential between the surface and the deep water is large enough. Air conditioning, ice-making, cooling of electrical power generating plants and of desalination plants to avoid thermal and brine pollution, and fresh-water production by desalination are some of the cooling applications.The high nutrient content of the deep water compared to that of surface water makes it a valuable resource for mariculture. Moreover, the use of deep water in mariculture systems bas many other advantages over inshore or estuarine surface waters: it is relatively sterile i.e. it is free of human disease-producing organisms, of shellfish parasites, predators and fouling organisms.