bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Continuing Evolution Of Satellite-Based Geodetic Positioning And Survey Navigation Capabilities
Authors: Stansell Thomas A. 
Published: October 2008

Introduction
Use of the TRANSIT Navigation Satellite System for offshore oil exploration and for land geodetic survey began in 1968. (To realize that we are well into the second decade of using this space-age technology for commercial applications was a slight shockto this author.) Many of the advances made in the state-of-the-art have been reported at previous Offshore Technology Conferences (see references 1, 2, 3, and 10). The purpose of this paper is to review the progress made since the previous reports and to examine trends affecting future developments.
This report covers three major areas. The first is the field of land geodetic survey in which three developments are reported. First is a multi-station network adjustment program called MAGNET. The second is a field translocation capability which has been implemented within the MX 1502 Satellite Surveyor instrument. The third development is a real-time translocation capability based on a communications link between two or more MX 1502 instruments.
The second area of this report focuses on the evolution of integrated navigation systems for offshore oil exploration. The objective is to show how these systems have matured since they were first described in references 1, 2, and 3. Also, trends affecting the direction of future developments are discussed.
Finally, this report evaluates the coming impact of NAVSTAR, the Global Positioning System. The future potential when the full satellite constellation is provided, the present potential with the interim six-satellite constellation, and concerns of the civil user community are discussed.

Geodetic Positioning

Background
One very important application of the TRANSIT Navigation Satellite System is for fixed point survey. In contract with satellite position fixes taken on a moving vessel, in which each position fix is used independently to update the dead-reckoned position, fixed point survey requires data from multiple satellite passes at a single location. With appropriate processing techniques such data can be used to obtain excellent survey results, thus avoiding the land traverse required with conventional survey techniques in which distance and angle measurements must be made from one point to the next, regardless of the intervening terrain.
Multiple pass satellite data can be processed in either of two ways: point positioning or translocation. In point positioning, data from a single receiver is used to obtain the .latitude, longitude, and altitude of its antenna. The only reference datum for this process is the satellite systemitself, and from 10 to 50 satellite passes normally are employed when operating in the point pos1tioning mode. A horizontal positioning repeatability of five meters rms can be expected with 25 satellite passes.
A variation on the point positioning technique is to employ a "precise ephemeris" rather than the orbit parameters obtained from the satellites themselves.
Natural Barrier Island Migration and Change - No Name Island, Beaufort Sea, Alaska
Authors: Gadd Peter E. , Gibson Dan H. , Nagel Robert H. , Sonu ChouIe J. 
Published: October 2008

Abstract
In March, 1981, Amoco Production Company constructed an exploration drilling pad on No Name Island, a natural barrier island located 14 miles northeast of Prudhoe Bay in the Alaskan Beaufort Sea. A monitoring program was initiated at No Name Island to determine the nature and extent of island change in response to the natural environmental forces active at the site. Two field surveys were conducted during the 1981 open-water season, the first in July and the second in September. Additionally, historical survey records and aerial photographs were investigated to determine long-term processes of island change.
The most significant changes observed between July and September, 1981, include island migration, island coalescence, and shoreline fluctuation. Although partially sheltered on its northern side by Cross Island, No Name Island exhibited changes similar to those observed on other Arctic barrier islands having more exposed locations.
At least two episodes of island breaching occurred between 1979 and 1981. The largest breach occurred near the northern end of the island and measured 300 feet in width. A smaller breach near the island midpoint has partially healed as a result of filling by littoral drift.
Between 1979 and 1981, No Name Island migrated southward at an average rate of 75 feet/year. On a long-term basis, the southward migration between 1949 and 1980 averaged 60 feet/year. The net littoral drift accounting for the observed long-term rate of migration is estimated to be approximately 50,000 cubic yards/ year.
Shoreline fluctuations adjacent to the drilling pad between July and September, 1981, measured 10 to 15 feet on both the east and west shores. These fluctuations were accommodated within the 30-foot wide beach-front margin which was specifically avoided as a site for the drilling pad foundation due to its unstable nature.
The recent history of No Name Island indicates the potential for dramatic short-term changes in both island shape and location. Cognizance of the major natural processes at work, provided by the monitoring program, will promote the proper design of future operations on the island while preserving the integrity of the island's natural environment.

Introduction
During the early months of 1981, Amoco Production Company constructed a drilling pad on No Name Island, a barrier island located approximately 14 miles northeast of Prudhoe Bay, Beaufort Sea, Alaska (Figure 1). No Name Island constitutes the southern component of the accurate Cross Island barrier complex and, unlike most of the barrier islands in this region, is oriented in an approximate north-south direction. Over the 4000 foot length of the island, the island profile varies from a minimum elevation of less than one foot and a minimum width of 20 feet at its northern extremity, to a maximum height of approximately five feet (above mean sea level) and a maximum width of 350 feet near its southern shore.
Wave Prediction in Shallow Water
Authors: Resio Donald T. 
Published: October 2008

Introduction
Considerable research has been concentrated on deep-water prediction in recent years. This has led to the development of rather sophisticated wave prediction schemes which have been tested successfully in field experiments under a variety of conditions. However, progress in deep-water wave prediction has not been followed by commeasurate advances in shallow water wave prediction. Since many offshore structures are located in relatively shallow water, this inability to obtain accurate predictions can have large economic consequences.
There are two types of shallow water wave-prediction which this paper intends to address. First, there is the situation in which the entire generation area lies in relatively shallow water. Second, there is the situation in which waves are generated in deep water can be integrated over all propagation directions and then propagate into shallow water. The first situation can be important in selected areas such as semi-enclosed basins, shallow bays or regions where ice cover can restrict the fetch area to a shallow region along the coast. The latter situation is important in coastal area all around the world, where large storm waves oropagate from deep water in to the coast.
The theory presently used by most engineers in estimating shallow water wave heights is based on published charts in the Shore Protection Manual (1973). Basically, the concept behind this theory follows from a theoretical treatment of direct atmospheric input into a monochromatic wave train with a simultaneous solution for the rate of energy loss due to bottom friction (Bretschneider and Reid, 1953). It is well known that the bottom friction factor is highly sensitive to bottom materials. Since the energy flux into the wave field from the atmosphere should be somewhat independent of bottom materials, this theory suggests that the predicted wave heights should be highly dependent on the bottom conditions. The published graphs in the Shore Protection Manual are specifically for a bottom friction factor 0.Ol.

Theoretical Treatment Of Wave Generation In Shallow Water
For surface gravity waves in a constant depth of water, the rate of change of a two-dimensional wave spectrum can be written asEquation (1) (Available in full paper) where E2 (f, ?) is the two-dimensional frequency direction spectrum, S2(f, ?)) is the net energy flux into (or out of) a spectral component, v is the group velocity vector and v is a horizontal gradient operator .In simple, idealized situations, equation 1 can be integrated over all propagation directions to obtain a representation of the rate of change - of the one-dimensional spectrum (Hasselmann et al., 1976).Equation (2) (Available in full paper) where x is the mean propagation direction and v xis the average group velocity along the x-axis and S1 E1 are the forms for S2 and E2 integrated around the propagation direction ?.
Hasselmann (1962) developed a theory for nonlinear wave-wave interactions which predicts a transfer of energy among various components in a spectrum.
Implementation of the Deep Seabed Hard Mineral Resources Act
Authors: Lawless J.P. 
Published: October 2008

Abstract
I welcome this opportunity to make a presentation for the Offshore Technology Conference about new Federal regulations, which were promulgated pursuant to the Deep Seabed Hard Mineral Resources Act and which are, among other things, designed to encourage the continued development of deep ocean manganese nodule mining technology. Although there have been many papers on nodule mining over the years, it is important to note that the industry is still in its development stage. In passing this law, the U.S. Congress recognized the evolving nature of the industry and the need not to stifle industrial development with unrealistic regulations. Our approach to the implementation of the statute has been within this context. The purpose of this paper is to summarize our approach in establishing this new regulatory program.
The statute which we are implementing sets up a legal structure pursuant to which U.S. citizens and companies can proceed with deep seabed mining pending the entry into force for the United States of an acceptable Law of the Sea Treaty. The law thus sets up a new element of certainty that did not exist before for these U.S. companies, and. it does so in several ways.
Probably first and foremost, it establishes a mechanism whereby they can obtain an exclusive priority of right to specified areas of the sea floor, within which they can continue with their seabed mining activities without interference by other miners.
The statute also has some other provisions which establish more certainty for the industry. These pertain to the orderly and responsible development of the industry, as well as provisions that provide for environmental sensitivity as seabed mining progresses.
In preparing to draft the regulations, before we started putting pen to paper, we sought out affected interests and initiated a dialogue to solicit their ideas on several of the issues that are set out in the statute, some of which are relatively complex. And we have developed, I believe, a good working relationship with the industry. We have found that the dialogue with the industry has been invaluable as we have been addressing some of these new and complex issues. We also talked with relevant Federal and state agencies, as well as public interest groups, to obtain the benefit of their expertise and to determine what their concerns and their thoughts were. So that by the time we developed our documents, even in draft form, we had the benefit of previous analysis and exchange with these affected interests, which was very productive and helped us to narrow our focus substantially as we proceeded.
By way of example, it may be useful to focus on some specific issues we have dealt with. With respect to the purpose of an orderly and responsible progression of the industry, the statute contains several provisions. For instance, in an application, a company must demonstrate to a reasonable extent that it will have both the financial and technological capabilities to engage in the mining activities proposed in its application.
Specialized Deep-Water Drilling Support Remotely Operated Vehicle
Authors: Nellessen Peter 
Published: October 2008

Abstract
Today there is renewed interest in deepwater drilling and production.1 Anticipating this trend, a concept for a specialized diving system to support deepwater drilling rigs is discussed and presented in this paper.
The ARMS Delivery Vehicle (ADV) system concept described herein is a deepwater, remotely operated vehicle (ROV) with capabilities equivalent to that of present day manned one-atmosphere rig support diving systems designed for intermediate water depths. This system can be fabricated using existing technology. Its configuration will be developed using historical operational experience to enable it to perform all the tasks required in rig diving support.
The rig support tasks are defined and critical vehicle components are then selected to fulfill the requirements for each task. After selection of components, three vehicle conceptswi11bi discussed. Comparison of these concepts will show that the ADV will be more effective than either a manned or adapted production ROV system in deep water. Finally, an economic comparison will show the ADV concept to be more cost-effective in water depths greater than 3000 feet when compared with manned systems and 5000 feet when compared with adapted production ROV?s.

Introduction
The Ocean Margi n Drilling Program and recent awards of deepwater leases have renewed interest in deepwater drilling. This in turn has generated new engineering studies and resurrected some of the deepwater concepts studied in the past. These studies have shown that drilling to depths of 8000 feet is feasible with modifications to certain existing offshore drilling vessels and equipment.
In the field of deepwater drilling, one question these studies have attempted to answer is, "What sub sea support will be required?". This has been answered in several ways but it is generally agreed that there is a lack of equipment capable of performing all rig support tasks required in deep water today. The only currently operational commercial system capable of performing work in depths exceeding 3000 feet is the Pisces VI manned free-swimming submersible, which is now installed on the Discoverer Seven Seas drillship.
For the purpose this paper, water depths are classified in the following depth rangesShallow- surface to 600 ft.Intermediate- greater than 600 ft to 3000 ft.Deep- greater than 3000 ft. to 8000 ft.Ultra deep- greater than 8000 ft.
This paper will discuss the concept of an effective deepwater drilling support diving system based on existing technology, combining features of both manned and unmanned vehicles. The equipment discussed is capable of using projected fiber optics umbilical technology advances to further increase its operating capabilities.
The concept discussed is called the ARMS Delivery Vehicle (ADV) by the author.
Problems Associated With the Specification of Castings for Offshore Application
Authors: Saunders G.G. 
Published: October 2008

1. ABSTRACT
Typical problems encountered in the specification and procurement of castings for offshore use are outlined. The significance of procurement policies, in respect of equipment and material specifications and vendor selection and control, in protecting the operator from avoidable costs and delays at the end of the procurement cycle, is discussed.

2. INTRODUCTION
The investigations and subsequent studies on which this paper is based have their origin in technical quality problems and associated delays encountered in the procurement of steel castings for pressure containing parts of an Offshore Installation. The initial problem concerned the rejection on the basis of visual appearance of one in a large order of castings, at a late stage in the procurement cycle. Further investigation revealed unauthorised and undeclared weld repairs on this and other castings. Subsequently, during a costly recovery programme, inconsistencies between the designer's specification, the supplier's custom and practice and code requirements were revealed and led to extensive technical discussions to resolve them. Further studies of several codes and standards has revealed severe gaps in their ability to meet the technical and economic needs of both purchasers and suppliers of cast steel products.
The principal problem areas concern the acceptance standards of visual and other non-destructive methods of examination prior to further processing which itself may reveal previously undetected but unacceptable flaws. Allied to this are practicalities of the heat treatment of weld repairs in situations where dimensional stability may be critical. The solution to these problems rely on making a realistic compromise between foundry practice, economic processing of castings and the technical requirements of the design. Some adjustments to existing codes and standards are recommended.

3. CAST STEEL AS AN ENGINEERING MATERIAL
This section outlines in a much simplified manner for non-specialists, the essential features of castings which affect their use for engineering purposes, as a background to later discussions.
The casting of metals is undoubtedly the second oldest profession it the history of mankind as we know it. The process of solidification of molten metal exhibits two principal features which give castings some of their characteristic properties. First, any impurities in the metal tend to be concentrated in the remaining liquid as solidification proceeds. An analogous process is that in which the controlled freezing of water/ alcohol mixtures enables the alcohol to be concentrated in remaining liquid following the removal of pure ice crystal & Second, the reduced volume of solid compared with the original liquid causes shrinkage to occur. This may give rise to cracking or tearing of the metal crystals, or where impurities of a gaseous kind (e.g. Hydrogen or carbon monoxide) are concentrated in the last liquid to solidify, may encourage the formation of porosity.
Scattering of Sound by Gas Bubbles in Water and Sediments
Authors: Ma Yushieh , Varadan V.K. , Varadan V.V. 
Published: October 2008

ABSTRACT
In this paper, a self-consistent multiple scattering approach with suitable pair-correlation function is employed to study acoustic wave propagation through water and sediments containing gas bubbles. The effects of surface tension, shear viscosity of the liquid and thermal conduction in the gas bubbles are considered in the analysis. In the Rayleigh limit, closed form expressions are given as a function of concentration of bubbles. Numerical results are presented for both phase velocity and coherent attenuation as a function of frequency near the fundamental resonance of the bubble for various values of concentration of bubbles.

INTRODUCTION
Gas bubbles in water and sediments control the long-range, low-frequency underwater sound propagation, especially at or near the fundamental resonance frequency of the bubbles. A bubble in water very effectively absorbs and scatters the sound wave when it propagates at or near the natural pulsation frequency of the bubble. Thus, sound propagating through an extended bubble swarm undergoes dispersion, and one is normally interested in studying the frequency dependent phase velocity and attenuation in such media.
During the past several decades, many empirical relationships and experimental approaches have been developed, and excellent review articles were published by Anderson and Hampton.l. Most of the available theoretical results are confined to single scattering approximations 2 which are strictly valid for very low volume fraction (concentration) of bubbles. It has been observed, however, that natural sediments contain gas bubbles as much as 16% by volume. For such media, the effects of multiple scattering on the sound propagation are of great practical importance.
In this paper, a self-consistent multiple scattering formalism using the T-matrix3 of a single scatterer in conjunction with a self-consistent pair correlation function is employed to study the phase velocity and coherent attenuation of acoustic waves in an elastic medium containing a random distribution of gas bubbles. This is based on the assumption .that gas bubbles are significantly larger than the individual sediment particles, and bubbles in sediments can be treated as if they were immersed in a continuous homogeneous elastic medium. 1 If the embedding medium cannot support shear waves, the model will then serve us to study bubbles in water. In the analysis of gassy water, the effects of surface tension, shear viscosity of the liquid and thermal conduction in the gas are considered. Numerical results are presented for both phase velocity and coherent attenuation as a function of frequency near the fundamental resonance of the bubble for various values of concentrations of bubbles.

FORMULATION OF THE PROBLEM
We consider N number of elastic scatterers which are referred to a coordinate system as shown in Figure 1. It is assumed that all scatterers are spherical in shape and have the same elastic properties.