bluuebunny/crossref_metadata_2025_split huggingface dataset:
Truss Spar Time Domain Inplace Structural Strength Analysis
Authors: Wang J. , Zhang B. , Berg S. 
Published: October 2008

Abstract
There are many unique challenging aspects in the structural analysis and design of a Truss Spar. This paper provides indepth discussions on inplace strength analyses of the truss structure based on the author's firsthand design experiences. Inplace structural strength design criteria are outlined, and an integrated procedure based on random wind and wave time domain analyses is presented. Technical issues related to structural and hydrodynamic modeling, computer software requirement, time domain environmental load simulation and extreme global load prediction for structural design, structural load mapping, and time domain design load case selection are discussed. Analysis results are presented for a generic Truss Spar design to illustrate the various loading conditions for the Gulf of Mexico environment and inplace structural behavior of the truss structure.

Introduction
The first two Truss Spars have been installed in 2001 in the Gulf of Mexico. More Truss Spars are currently in various design and fabrication stages, and will be installed in the future. Compared to the Classic Spar, the Truss Spar design replaces the cylindrical midsection of the hull with the truss section as shown in Figure 1, hence the name Truss Spar. The truss section is a space frame consisting of tubular members similar to a jacket type structure. The truss structure is inherently more efficient, with well over 50% less steel weight than the plated cylindrical midsection of the Classic Spar, as a structural link between the upper hard tank and the soft tank at the keel of the platform. The heave plates are integral parts of the truss design, normally consisting of a stiffened plate structure with girders supported by the truss horizontal braces, knee braces and vertical braces. The main function of the heave plate is to provide added mass and damping for heave motion of the Spar platform. The truss and heave plates also provide lateral support for the risers.
For inplace conditions, the truss structure is subjected to continuous dynamic loading due to wave excitations and Spar motions. Since the truss section has the least structural redundancy compared to the hard tank and the soft tank, considerable structural analysis and design efforts are required to ensure the adequacy of the truss and its connections for structural strength and fatigue. Unlike the tension leg platform and other floating platform concepts, the Spar platform is a truly compliant system, whose natural periods for all the six degrees of freedom of motions are significantly greater than the predominant wave period. Hence, the low frequency loads, such as slow varying wind load, wave drift force, and second order nonlinear wave excitations, will have significant impact on the dynamic response of the Spar. In particular, the time varying dynamic wind load contributes significantly to the pitch/roll motion, which in turn contributes the most to the global bending moment and shear force in the truss structure.
High Resolution Surveys With Auvs
Authors: Willcox Scott , van Mierlo Frank 
Published: October 2008

Abstract:
In the past two years, Bluefin has fielded several AUV systems. The survey systems that Bluefin build for the US Navy have seen almost continuous use. In addition to the Bluefin operations these vehicles participated in three Navy Exercises and one international science cruise. This paper presents the results of some of these high-resolution surveys. Figure 1:(Available in full paper) Figure 2:(Available in full paper)

Introduction
After developing several key AUV technologies at MIT and building 12 prototype vehicles in the process, the Bluefin team became a commercial enterprise in the fall of 1999. Bluefin's engineers have now built seven new AUVs for a range of commercial, military, and academic customers. Measured in terms of numbers of vehicles sold, Bluefin Robotics is the world's largest commercial manufacturer of autonomous underwater. Figures 1 through 5 show several of Bluefin's AUVs in action. This paper presents some of the field data that was taken with these AUVs. Specific data of the Bluefin 5000 is presented in detail. Both the sonar and the navigation data shows the success of Bluefin's "small is beautiful" design philosophy. Bluefin's current class of vehicles are the smallest survey systems in the commercial survey market. Current development efforts at Bluefin are pushing the envelope even further by fielding a new class of AUVs with a diameter of 12.75 inches. Modularity is crucial to this new design and it will allow the integration of a whole new class of survey sonars. Current developments in synthetic aperture sonars are particularly exiting and promise to revolutionize the way that data will be gathered in the not so distance future. Simultaneously, Bluefin is pushing the state of the art in the areas of mission autonomy, energy sources, and navigation systems.

Bluefin 5000
The BLUEFIN 5000 is part of the new Odyssey III class of vehicles that that have been designed by Bluefin. The BLUEFIN 5000 is specifically designed for wide-area high resolution surveys missions. As such, the vehicle's main payload is a high-resolution, multi-beam side-scan sonar, the Klein 5000. The BLUEFIN 5000's oceanographic payload sensors include CTD, fluorometer, and light-scattering sensors. The design of the BLUEFIN 5000 is modular, with all essential vehicle components (main electronics pressure vessel, computation, propulsion, navigation and attitude sensors) contained in the aft modular section of the vehicle. The forward modular section contains the Klein 5000 sidescan sonar, the CTD, the fluorometer, and the light-scattering sensor. The forward modular section also contains two redundant battery packs in separate battery housings. Spent battery packs are easily replaced by removing the BLUEFIN 5000's hemispherical nose-cone, sliding each cylindrical battery housing out of the vehicle, and then re-inserting charged batteries. The forward battery arrangement allows the vehicle to be serviced rapidly between missions, with on-deck turn-around times as short as 30 minutes, excluding data download.
Embankment Construction on Yielding Sea Bottom
Authors: Stamatopoulos Aris C. , Kotzias Panaghiotis  C. 
Published: October 2008

THE APPROACH
Conventional embankment design practice calls for a factor of safety against base failure higher than 1, usually of the order of 1.5. Such factor of safety would exclude the construction of embankments in projects where no practical alternative exists. Moreover, as marine embankments are often less costly than structures on piles, there is considerable economic advantage in constructing them to the maximum possible extent.
The approach used in the design and follow-up of construction of the embankments described in this paper differs from the conventional approach. In the four cases presented the design was not based on some fixed value of the factor of safety. The location of expected failure along the embankment axis was estimated, and as embankment construction came near this location, measurements were taken to obtain early warning of failure. As embankment construction proceeded beyond the location of the first appearance of failure, the extent and consequences of the failure were followed quantitatively. Construction was discontinued when the consequences of base failure exceeded a certain tolerable limit.
This approach, allowing construction under a condition of a factor of safety less than 1, has been found satisfactory in the marine embankments discussed in this paper. In these projects,the soft clay supporting the embankment was of low sensitivity,a base failure could not cause damage to any adjoining structures,there was no construction alternative of a comparable cost andthe owner had been advised of the expected base failure.

APPROXIMATE STABILITY EQUATION
A stability equation based on simplifying assumptions is as follows (derivation is presented in Appendix, A):(Mathematical Equation available in fullpaper)
where c is the average cohesion (equal to the shear strength) of the soft clay supporting the embankment; h1 and h2 are the heights of the embankment above and below water level, respectively, when failure is just starting; r1 and r2 are the unit weights of the embankment material above and below water level, respectively; s is the cotangent of the angle of the embankment slope with the horizontal; and d is the depth of the soft clay layer supporting the embankment.
Simplifying assumptions are as follows:base failure develops along a single cylindical surface,axis of cylindrical Simplifying assumptions are as follows:base failure develops along a single cylindical surface,axis of cylindrical surface of failure passes through the toe of the slope of the embankment,radius of cylindrical surface is equal to the depth d of the soft layer,strength of soft clay is equal to cohesion (angle of internal friction is zero),embankment material offers no shear resistance andd ? (hl + h2) s.
Assumption 1 is commonly accepted in stability problems involving sliding.
Parametric Study of Steel Weight of Large Oil Tankers
Authors: Johnsen Inge , Hagen Erik , Boberg Bjørn 
Published: October 2008

Abstract
The steel weight constitutes a major factor of the production cost of a ship as well as being indirectly an important factor with respect to the operational cost efficiency of large tankers.
The study presents an outline of the influence of parametric variation in main design characteristics of oil tankers with respect of steel weight.
The characteristics which have been discussed are main dimensions, steel qualities and primary and secondary structural arrangements. The vessel sizes will vary from 50.000 t.dw. to 500 .000 t. dw.
The parametric study also includes variations with reference to hull steel weight of internal arrangement and optimization of part structures. The influenceof non-dimensional parameters (LID, LIB, etc.) have been dealt with in this connection. The study is based on the Rule design programs (CBC-programs) of Det norske Veritas. The results of the study are so presented as to facilitate fast and easy application on actual design projects.

Introduction
The built-in steel of a ship constitutes a substantial part of the total cost of the ship. It is therefore important both for the shipbuilder and the ship owner that the weight may be estimated at the project stage with an acceptable degree of accuracy.
As the ships, particularly oil tankers, combined carriers and bulk carriers, have increased so rapidly in size during recent years, it may be difficult for shipyards to apply their weight statistic and their usual methods for weight estimates at the project stage. These estimates are usually based on weight relationships which apply to basis ships or sister ships together with corrections which have relevance to the deviations of the particular design from the design and dimensions of the basis ship. Many useful weight calculation methods have also been published, such as cubic number, weight per foot, method of differences, group eights as well as detailed calculation. [5], [6], [7]. These conventional method: may be applicable when they are adjusted to current yard practice, owner's requirements etc.
Another way of supplying weight data is to apply the requirements of classification societies directly to the ships in question and have the corresponding scantlings and the steelweights calculated. This method will generally require the use of computers to carry out dimensioning of structural parts and scantling selection. This is, needless to say, an extremely powerful method. One can carry out weight studies of a series of ship projects and work out optimum designs in a short time at low cost, and more efficiently than by other "short-cut" methods.
As only a very limited set of ship data are available at the initial project stage, such a method should not require much information about the ship in question. Such a method has been applied in the rule programs (CBC) developed by Det norske Veritas.
Telecommunications Offshore
Authors: Summers James H. 
Published: October 2008

Abstract
A survey of telecommunications systems and equipment now in use by offshore operators is presented. The costs, effectiveness, and availabilities of the various services and systems is evaluated and comparitive analyses are offered. A discussion of new services and hardware is undertaken with studies of their costs, capabilities, and limitations according to geographic location. The paper concludes with informal remarks by the author concerning telecommunications as a service offshore and attitudes toward it within the offshore industry.

Introduction
The physics, electronics, logistics, and politics of offshore oil exploration and production are such that telecommunications for that phase of the industry is somewhat different than for similar applications ashore. Radio waves propagate differently, the environment is generally more severe, maintenance activities are more costly, and since offshore work is simply more expensive than for similar activities ashore, the communications user on the geophysical vessel, supply boat, or drilling rig has come to demand a measure more from his system or service. He may be getting it and not know it; he may not be getting it but thinks he is. Good communications, like good food, is an elusive creature.
Just as in every other specialized field related to petroleum, communication has a vocabulary all its own, and a fair comprehension of this terminology is essential to a basic understanding of the subject. If the reader is not thoroughly familiar with the jargon used in the industry, he might benefit from looking over the short glossary at the end of this paper before proceeding. Some of the definitions are my own and may not have the same meaning to others. Even among communications specialists one can find disagreement over basic terminology. I would ask the expert reader to overlook any misnomers he may find and that the uninitiated accept the definitions as accurate within the scope of this paper.
Telecommunications is not an end in itself. It has but one purpose in offshore activities: to provide a service to the user, and to do only to the level of sophistication needed, and at the lowest possible cost. Perhaps in no other service activity is it easier to misjudge what is best. Hence, the purpose of this paper: to try to sort out the myriad systems and services available offshore, define and evaluate each to a reasonable degree, and to make recommendations as to how to proceed for the several "predictable" types of offshore activities. We will try to take into account as many of the variables in the problem as possible such as the unfortunate variations in legal restrictions from place to place, and the differences in public communications service availabilities and costs.
Finally, we will not delve too deeply into the technical aspects of communications.
Reliability of Circular Piles Subjected to Ocean Waves
Authors: Schueller Gerhart I. 
Published: October 2008

1. Introduction
Wave forces exerted on structures are of vital interest to offshore drilling stations and various other marine structures. Because the piles constitute the major or entire support for the whole structure the engineer must ensure that those piles successfully withstand the forces to which they are subjected. In this regard, the most important piece of information is the occurrence of wave forces at the site of the proposed structures.
The design problem is complicated by a number of factors. First, wave characteristics change as a wave approaches the shore. Secondly, local wind-generated waves become superimposed on large ocean waves, creating a complicated surface. Thirdly, the forces exerted by waves of similar properties vary greatly. This variation is caused by fluctuations in fluid particle velocities as well as eddies and turbulance around piles caused by the rapidly reversing flow. Consequently, a deterministic approach to wave force prediction appears to be impossible.
As an alternative method in design, an engineer might determine his design by using a cumulative distribution function (CDF) of wave forces created from field data. If the distribution of wave forces is known, the engineer can then make reliability statements about his design.
The method used here utilizes a multiple linear regression analysis to develop a relationship between wave properties and the parameters 1 used in the Morison force equation. These parameters include velocity and acceleration of water particles and the drag and mass coefficients.
Using Monte Carlo simulation these regression relationships are then utilized to develop the probability density formation of wave forces.

2. Description of Force Equation
The forces exerted by ocean waves on a pile is one of the most complicated fluid flow problems because of the presence of both unsteady and oscillary motion. The generally accepted formula for a wave force on a pile is the so-called Morison formula,(Mathematical equation available in fullpaper)
The first part of this equation represents the for drag caused by surface shear. The second part is the acceleration force on the displaced volume of fluid including the virtual mass effect. The relative importance of inertia force increases with the ratio of the pile diameter to wave height.
Although the particle motion in waves is orbital, the method is based on flow. The fluid density and the pile diameter D are assumed to be constant. It is also assumed that the drag force and the inertia force can be treated separately, and the total force can be obtained by adding the solutions linearly. In previous investigations 1,2,3,4,5,6 water particle velocity and acceleration were calculated by stokes7 irrotational theory. The theory considers only waves of small but finite wave steepness.
Cost-Effective Design and Development of Hub Platforms
Authors: Huff Scott S. , Heijermans Bart 
Published: October 2008

Abstract
El Paso Energy Partners, L.P. ("EPN") has developed a portfolio of shelf and deepwater hub platforms with access to the flextrend and deepwater regions of the Gulf of Mexico. These hub platforms serve as production facilities for local and off-lease production and as gathering, pumping and compression stations for EPN's oil and gas pipelines.
This paper discusses the key technical considerations and strategies involved in the cost-effective design and development of these hub platforms. The paper addresses the design of new platforms and the re-development or expansion of existing platforms. Both fixed and floating facilities are considered.

Introduction
Hub platforms serve as central points for gathering, redistribution, and transportation of oil and gas. These platforms can also serve as primary processing facilities for local or off-lease production, pumping stations for oil pipelines, and/or compression facilities for gas pipelines.
This paper describes various strategies that can be employed to optimize the design of new hub platforms and the development of existing hub platforms. These strategies are intended to:ensure operability and reliability,preserve flexibility for future expansion, andoptimize current and future costs.

EPN's Hub Platforms
EPN owns various hub platforms in the Gulf of Mexico, as displayed on the map in Figure 1. These platforms are an integral part of EPN's infrastructure, since they host pumps and compressors and also act as portals for supply into the downstream pipelines.
Figure 1: EPN's Hub Platforms (Available in full paper)
EPN owns the following hub platforms in the Gulf of Mexico:

VK 817.
The VK817 platform is located in Viosca Knoll Block 817 in the Eastern Gulf of Mexico. The platform is situated in a water depth of 671 feet and was installed in 1995. The platform is designed to process gas and condensate production at maximum rates of 150 million cubic feet of gas per day ("MMCFD") and 5,000 barrels of condensate per day ("BCPD"). The platform serves as a junction platform for EPN's Viosca Knoll Gathering System and hosts a Taurus 60 driven gas compressor and a slug catcher for the Ram Powell gas pipeline. The platform processes production from EPN's VK817 field and from the Walter Oil & Gas deepwater field in Viosca Knoll Block 862. The platform was designed to:accommodate future tie-backs from the flextrend and deepwater, andhost additional compression for the incoming pipelines.

SS 332A.
The SS332A platform is located in Ship Shoal Block 332 in the Central Gulf of Mexico (Figure 2). The platform is situated in a water depth of 438 feet and was acquired by EPN from Arco Oil & Gas Company in the early 1990s. Arco's production from the SS332 field had ceased, and the platform was of value to EPN to support the Leviathan Offshore Gathering System, the predecessor of the Manta Ray Gathering System. SS332A became a cornerstone in the Poseidon oil pipeline system ("Poseidon") when EPN constructed Poseidon in 1995 and the Allegheny Oil Pipeline in 1999.
Modeling of Wind Over Water
Authors: Shemdin Omar 
Published: October 2008

Abstract
Modeling of wind over water can provide a useful tool in dealing with the nearshore and offshore environment where the wind stress plays a dominant role. The available field and laboratory information on shear stress coefficients is reviewed with emphasis on differences between field and laboratory conditions. Modeling relationships are proposed for the wind and the wind generated current. The procedure is applied to a laboratory model of a lagoon in the Atlantic trade wind region. Alternation of the physical boundaries produced a significant change in the wind induced circulation. The change in water circulation was used to predict the increase in the temperature of water used for cooling purposes.

Introduction
Modeling of wind over water can be useful in arriving at solutions to engineering problems where wind plays a dominant role in water circulation. Use of wind models is feasible provided the scale of the modeled area is small enough so that the effect of earth rotation may be neglected.
The available information on wind and wind driven circulation in the literature is primarily aimed at understanding and/or describing the properties of the shear flows in air and the induced motion in water. An abundance of field and laboratory results are reported but only a few studies provide insight relevant to modeling of wind over water. The question of what to model and to what scale is a central question. The scope of this study is limited to those problems where the wind plays a dominant role in the water circulation. In areas where both the tides and the wind are important the two effects may be included in a composite model.

Review Of Field And Laboratory Results
Of the many studies reported in the literature on air-sea interaction only a few are relevant to the scope of this study. In the field Van Dorn (1953) investigated the set-up and the surface drift in a pond under the action of the wind. By spreading a detergent on the water surface to suppress the wind generated waves he found the surface drift to remain constant. Keulegan (1951) found the surface drift to be 3% of the wind speed. The surface drift has been reported to vary from 2.4% to 5%. The 3% value appears to be a reasonable average.(Available In Full Paper) where K is the Von Karman constant and zoa is the roughness height. Such a profile is not uniformly endorsed by all investigators. Most recently De Leonibus (1971) reports that seldom did he encounter a logrithmic distribution in his field measurements of the wind profile using four cup anemometers. Ruggles (1969), however, indicates that 90% of his field measurements of the wind profile followed the logarithmic distribution. In the laboratory Lai and Shemdin (1971) reported that the wind profile can be approximated by a logarithmic distribution.