bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methicillin‐resistant Staphylococcus aureus bacteraemia and epidural abscess in a neonate
Authors: Stewart Phoebe , Khatami Ameneh , Loughran‐Fowlds Alison , Isaacs David 
Published: September 2014

AbstractA 24‐day‐old boy presented with fever, irritability and poor feeding. Blood culture grew methicillin‐resistant Staphylococcus aureus. Cerebrospinal fluid analysis showed pleocytosis, and methicillin‐resistant Staphylococcus aureus grew from enrichment broth. Magnetic resonance imaging revealed an epidural abscess extending from C2–3 to T8–9. Staphylococcal infections of the central nervous system are uncommon in neonates. This case demonstrates the importance of performing a lumbar puncture in isolated staphylococcal bacteraemia. The case also highlights that cerebrospinal fluid pleocytosis may indicate a parameningeal focus of infection.
Design Parameter Reliability Analysis of Induction Bends
Authors: Akula Venkata M. K. , Hill Lance T. 
Published: September 2014

Induction pipe bends are essential multi-functional components in offshore applications performing not only as fluid conductors but also as structural members providing flexibility to the entire pipeline. The deforming mechanism of bends minimizes the effects of pipe walking, length changes due to thermal expansion/contraction, etc. However, the extent to which the bend deforms to counteract the pipeline deformation, prior to reaching plastic collapse, is dictated by the design variables. The pipe bend design variables include the geometry of the bend, the inelastic material properties, and the operating loads. The study of the influence of these variables is central to improving upon existing bend designs and is the focus of this research.
The certification process for bends typically involves ensuring the pipe bending moment is within limits set by agencies such as DNV, ASME, etc. Closed form solutions for the bending moment do exist but they often do not consider the effects of large deformation and the material nonlinearity of the bends. Since it is impractical to perform physical tests for every possible design, numerical techniques such as the finite element methods are an attractive alternative. Furthermore, for a given bend design, the design variables are prone to deviation, due to manufacturing process, operating conditions, etc., which introduces variation in the structural response and the resulting bending moment.
In this paper, a nonlinear finite element analysis of induction bends is discussed followed by a presentation of a simulation workflow and reliability analysis. The finite element analysis utilizes a nonlinear Abaqus model with an user-subroutine prescribing precise end loading and boundary conditions. The workflow utilizes the design exploration software, Isight, which automates the solution process. Thereafter, reliability analysis is performed by varying the design variables, such as bend angle, ovalization, etc. and the results of the simulation are presented.
The objective is to illustrate a solution technique for predicting the induction bend load carrying capacity and to examine design robustness. An automated workflow is demonstrated which allows for quick design variable changes, there by potentially reducing design time. The reliability analysis allows analysts to measure the variation in the load carrying capacity resulting from the deviation of design variable specifications. These demonstrations are intended to emphasize that to ensure the success of a bend design, it is important to not only predict the load carrying capacity accurately but also to perform reliability analysis for the design.
Development of a Model for Global Response of Ship Hull During Ramming of Heavy Ice Features
Authors: Ringsberg Jonas W. , Broman Mathias , Nordqvist Per 
Published: September 2014

Ice-induced global forces that affect a ship’s hull when colliding with heavy ice features are analysed. The objective was to increase the knowledge of what structural loads a ship encounters during Arctic operations and thereby contribute to safer shipping in the Arctic. In the study, a model was created that used recorded motions of a ship when it collided with a heavy ice feature in order to calculate the global forces that affect the ship hull.
The motion data were collected by Det Norske Veritas during the Coldtech research project on board of the Norwegian Coast Guard vessel KV Svalbard. To give an understanding and background to the problems that the model needs to handle, the paper includes a brief review of ice-ship interaction and hull monitoring. The model developed is limited to perpendicular collisions and the first impact sequence, since only then the impact location can be considered as known. The forces resulting from the model are compared with the design loads of ice class rules, since the same impact type is considered. The results are also compared with previous work done in the area. From the comparisons it can be seen that the forces calculated with the current model seem to be reasonable as they are in the same order of magnitude. However, more measurements are required in order to fully verify the model and the measured motions.
Case Studies From Implementation of the First Commercial Leasing Processes for Areas of the Outer Continental Shelf (OCS) Under the U.S. Renewable Energy Regulations, 30 CFR 585
Authors: Trager Erin C. 
Published: September 2014

President Barack Obama announced on April 22, 2009 that the U.S. Interior Department (USDOI) had completed the Final Renewable Energy Framework or rulemaking process (i.e., regulations) to govern management of the Renewable Energy Program for the U.S. Outer Continental Shelf (OCS). The Bureau of Ocean Energy Management (BOEM) within USDOI is responsible for overseeing the implementation of this framework. It establishes a program to grant leases, easements, and rights-of-way for orderly, safe, and environmentally responsible renewable energy development activities, such as the siting and construction of offshore wind generating facilities on the OCS, as well as other forms of renewable energy such as wave, current, and solar.
To date, five commercial wind energy leases have been issued for areas on the U.S. OCS and several other areas are at various stages in the process leading to leasing. The leases issued for two states in particular — Delaware and Virginia — help serve as case studies for how the U.S. regulatory process for ocean wind leasing operates. This paper will discuss the process by which these leases were issued and next steps, which will illustrate the implementation and best practices of the U.S. regulatory process for offshore wind leasing.
The Key Mechanics Principles for Vortex-Induced Vibrations
Authors: Zueck Robert F. , Palo Paul A. 
Published: September 2014

Vortex-Induced Vibrations (VIV) are cyclic motions in flexible slender structures that are induced by the shedding of vortices mostly transverse to the length of the structural member. The authors contend that the complete three-dimensional (3D) geometric changes that evolve in the structure are too often overlooked when investigating the basic physical nature of VIV. In this paper, we use a physics-based numerical model of a cable (a specific type of slender structure) to demonstrate the following mechanics principles:
• Fluid drag (or other field loading) results in 3D geometric changes in a suspended cable.
• Those changes necessarily include a lack of structural stiffness in the cable transverse to fluid flow.
• In those instances, the structure will inevitably deflect to any kind of transverse action, particularly fluid vortices.
• The nonlinear nature of this mechanism allows VIV to occur over a range of time periods, often called “lock-in.”
Although the vortex shedding in the fluid provides the necessary repetitive inducement action, the evolving geometry of flexible slender structure appears to be the dominant factor concerning the actual nature (amplitude, pattern, etc.) of the resulting VIV behavior.
Coupled Dynamic Response of a Spar Type Floating Offshore Wind Turbine
Authors: Peng Cheng , Yan Fasuo , Zhang Jun 
Published: September 2014

FOWTs (Floating Offshore Wind Turbine) are feasible renewable devices to harness the wind energy in the near future. However, because of the complicated interactions among wind turbine, mooring system and the hull, the motion of a FOWT under the impact of severe wind, wave and current has not been well studied yet. This research focuses on the coupled numerical analysis of a FOWT. A numerical code COUPLE-FAST is developed by integrating two existing codes, namely, COUPLE and FAST, to carry out the task.
In this study, a particular FOWT model is chosen for the numerical simulation, which consists of a NREL 5-MW baseline wind turbine and OC3-Hywind Spar. Although the numerical simulation is limited to this particular type of FOWTs, the results and related code (COUPLE-FAST) may be helpful to the design of FOWTs in the future.
Coupled Analysis of SCR and Flowline Under High Pressure and High Temperature
Authors: Luk C. H. , Qi Xinhai , Zhong Jianxia 
Published: September 2014

This paper presents a coupled design analysis for a Pipe-in-Pipe (PIP) Steel Catenary Riser (SCR) and Flowline (FL) system in 5000ft of water under high pressure and high temperature (HP/HT) conditions in the Gulf of Mexico (GOM).
The finite element program ABAQUS is used to model the inner and outer pipes of the PIP system, the centralizer, the SCR hangoff, the flowline lateral and end supports, and pipe-soil interactions on the seabed. Thermal stresses and stress ranges caused by repeated temperature transients, axial and lateral displacements of SCR and flowline, as well as by the dynamic responses of the coupled riser and flowline system, are presented. Comparisons are also made with results by ABAQUS models with beam and pipe elements, and results obtained by coupled and de-coupled analysis. The sample vessel motion was obtained for an example Spar platform in GOM.
Fusion Zone Microstructure Associated With Embrittlement of Subsea Dissimilar Joints
Authors: Dodge M. F. , Dong H. B. , Gittos M. F. , Mobberley T. 
Published: September 2014

Within subsea oil and gas systems, nickel alloy filler metals are commonly used in the joining of ferritic steels with different mechanical properties. An example of this is the joining of low alloy steel (LAS) forged manifold hubs (e.g 8630 or F22) to low hardenability pipelines steels, such as X65). The joint is part of a two stage welding process that simplifies offshore installation. Initially, a weld deposit is made on the forging using a multi-pass ‘buttering’ technique, providing intermediate layers of a suitable material, such as Alloy 625. A postweld heat treatment (PWHT) is applied to the buttered forging, onshore, to temper the hard heat affected zone (HAZ). After machining a bevel into the buttering layer, a closure weld, applied offshore, is employed to join the pipeline to the forging. As the buttering layer and linepipe are not critically hardened by the closure weld, no PWHT is required.
To prevent corrosion, subsea systems of this kind, are subjected to cathodic protection, via aluminium based anodes. Whilst successful in protecting the ferritic parts within the manifold structure, a number of high profile failures has been attributed to the evolution and ingress of hydrogen, and its diffusion to, the fusion zone of the dissimilar weld.
To investigate the susceptibility of fusion zone microstructures to hydrogen embrittlement, three dissimilar weld samples were fabricated: 8630-Alloy 625, F22-Alloy 625 and F22-309LSi. The latter is not a combination normally used to complete joins of this type. Each specimen was the subject of thermodynamic and kinetic modelling studies using Thermo-Calc™ and Dictra™, with microscopic examination by scanning electron microscopy (SEM) combined with energy-dispersive X-ray (EDX) and electron backscattered diffraction (EBSD). Nano-scale features were also investigated by transmission electron microscopy (TEM). By comparing the fusion zones of the three different joints in both as-welded and heat-treated conditions, the metallurgical aspects relating to hydrogen embrittlement are revealed. The results indicate that precipitates, which form in a zone of carbon diffusion during PWHT, are particularly harmful in the presence of hydrogen. The formation of this hydrogen susceptible region is partly due to the initial solidification structure morphology, the formation of which is also discussed.
Evaluation of Pressure Change While Steady-State Tripping
Authors: Podryabinkin Evgeny , Ahmed Ramadan , Tarasevich Vladimir , May Roland 
Published: September 2014

Excessive tripping speed in an uncased borehole increases the risk of having formation damage or influx of formation fluid (kick). However, if the tripping is performed at lower speeds, the operation requires more rig time. Hence, increased trip speed cuts expensive rig time. These opposing goals require thorough planning and optimization of the tripping operation to avoid operational problems and reduce financial expenditures. To maximize the tripping speed, accurate prediction of the pressure change occurring due to the axial pipe movement (surge or swab pressure) is necessary. The pressure change is influenced by the hole and string diameters, eccentricity, fluid properties and trip speed. The tripping speed is one of the operational parameters, which are regularly adjusted at the rig site.
Analytical solutions exist only for special scenarios. The semi-analytical models for calculation of the steady-state pressure change cannot provide accurate predictions. They are mostly based on disputable assumptions which make the model to underestimate the pressure change. Most of the existing models are based on the parallel-plate approximation of the annular geometry. In another approach, the parameter, which reflects the amount of fluid which is dragged the direction of the string, assumed to be constant or calculated independent of the fluid viscosity.
In this paper, accurate solutions were obtained from direct numerical simulation of flow in a cylindrical annulus with axial movement of the inner cylinder. The numerical algorithm is based on finite volume method and incorporates laminar flows of Newtonian, Power Law, Bingham Plastic and Herschel-Bulkley fluids. The method predicts the pressure change occurring in concentric and eccentric annuli with and without rotation of the inner cylinder. The goals of this work are to: i) study the influence of the eccentricity, fluid properties and tripping speed on the pressure change; and ii) evaluate the accuracy of the simplified approaches by comparing experimental data and numerical solutions, and determine their validity ranges.
This paper presents a new method for finding trip-caused pressure change in the wellbore through systematic analysis of the numerical solutions. Parametric study was performed to examine the effects of different influential parameters on the pressure change. In addition, the results obtained from the numerical method are compared with the simplified solutions and the discrepancies are analyzed to show the improved accuracy of the new method.
Ice Condition Database for the Arctic Sea
Authors: Tõns Tõnis , Erceg Sandro , Ehlers Sören , Leira Bernt Johan 
Published: September 2014

Increasing trends in the arctic sea transport lead to the necessity to determine route specific ice conditions to ensure safe vessel transits. In order to achieve this, the comprehensive understanding of ice conditions from the past should be used to predict future trends for arctic sea ice conditions.
This paper presents the development of such ice conditions database with the implementation of a satellite data source, which will become a basis for the determination of route specific ice conditions. A case study is performed in order to show how the database could be used to collect the route specific ice data for statistical analyses.
The Shielding Effect of Drilling Fluids on MWD Downhole Compasses: The Effect of Drilling Fluid Composition, Contaminants and Rheology
Authors: Saasen Arild , Ding Songxiong , Amundsen Per Amund , Tellefsen Kristoffer 
Published: September 2014

Materials such as added clays, weight materials, drill solids and metalic wear products in the drilling fluid are known to distort the geomagnetic field at the location of the Measurement While Drilling (MWD) tool magnetometers that are used to measure the direction of well path. This distortion contributes to substantial errors in determination of azimuth while drilling deviated wells. These errors may result in missing the target of a long deviated 12 ¼″ section in the range of 1–200m; representing a significant cost to be mitigated. The error becomes even more pronounced if drilling occurs in arctic regions close to the magnetic North Pole (or South Pole). The effect on the magnetometer readings is obviously linked to the kinds and amounts of magnetic materials in the drilling fluid. The problem has recently been studied by laboratory experiments and analyses of downhole survey data.
A series of experiments has been carried out to understand how some drilling fluid additives relate to the magnetic distortion. Experiments with free iron ions show that presence of iron ions does not contribute to magnetic distortion; while experiments with bentonite-based fluids show a strong effect of bentonite on magnetic shielding. Albeit earlier measurements showing a strong dependency of the content of organophilic clay, clean laboratory prepared oil-based drilling fluids show no increased shielding when adding organophilic hectorite clays. The anticipated difference between these two cases is outlined in the paper. When eroded steel from an offshore drilling site is added into the oil-based drilling fluid, it is found that these swarf and steel fines significantly increase the magnetic shielding of the drilling fluid. The paper outlines how the drilling direction may be distorted by the presence of these additives and contaminants and how this relates to the rheological properties of the drilling fluid.
Hybrid Riser Tower Design: Evolution, Operational Efficiency and Compliance to Ultra Deep Offshore Challenge
Authors: Gueveneux Hervé , Le Buhan Philippe 
Published: September 2014

The riser system selection and sizing is one of the most challenging design issues of the subsea world specifically for deepwater applications. Bundle riser towers have been used for few deep water developments since the late 1990s and have demonstrated their capacity to meet the operational constraints in terms of field layout congestion, flow assurance, mechanical design, fabrication and installation etc.
From the pioneer application in the Gulf Of Mexico (Green Canyon 29 – 1988) to the 2nd generation systems in Western Africa (GIRASSOL to Rosa or CLOV), the design of Hybrid Riser Towers has evolved to improve mechanical robustness, installation efficiency and operability. This article reviews the past evolutions and gives an overall view of the performance achieved so far, mainly in West African sectors. The move of the offshore industry towards ultra-deep (WD > 1800m) and/or marginal fields may trigger some additional design evolutions which are highlighted in the article, with a focus on the water depth increase considering environmental conditions met on previous projects. The feasibility in harsher conditions is not addressed in this document.
In addition, the challenges raised by the engineering of such deepwater Hybrid Riser Tower concepts are discussed:
• Structural models of different scales shall be used to properly account for potential couplings between the global behavior of the whole tower with the local responses of each individual component;
• Top and bottom assemblies as well as the rigid or flexible spools, the piping and connectors shall be introduced into the FE models to define correct boundary conditions to the HRT;
• Slug or severe internal flows shall be considered for fatigue issues requiring complex models which combine CFD and structural calculations;
• Risks of hydrodynamic instabilities shall be assessed like plunge and torsion galloping for non-cylindrical sections and VIV for bare peripherals;
• A specific attention shall be paid to the fatigue budget spent from towing and Installation to the In-place configuration.
Advancements in Deepwater Drilling Riser Modelling
Authors: Bohan Paul , Lang Donogh 
Published: September 2014

Experience with modern ultra-deepwater capable drilling vessels and their associated marine riser tensioner systems has led to increased concerns over tensioner load variations in extreme environments. Modern drilling riser tensioners are complex hydro-pneumatic systems whereby the tension applied at the slip-ring can vary significantly with tensioner stroke in response to vessel heave.
The aforementioned tensioner load variations that occur with modern tensioner systems can have a significant effect on the loads transferred to the wellhead and conductor/casing. This can lead to fatigue concerns at critical locations. The connectors along the conductor and surface casing can be highly susceptible to fatigue if they are located in regions of high bending loads below the mudline.
This paper will give a detailed overview of recent technology advancements that have been incorporated into the latest version of an industry-standard tool for global analysis of drilling risers [1] and that allow these concerns to be addressed. It will focus on two main areas where significant enhancements have been made in tensioner and wellhead & casing modelling. (Note that the version of the software incorporating these capabilities will be made commercially available during 2014.)
The advanced tensioner modelling capability consists of a detailed tensioner model that includes individual hydraulic and pneumatic components of the tensioner system that are fully integrated with a non-linear 3D structural finite element model. This tensioner model is capable of fully capturing all transient behaviour and load variations of real world tensioner systems. This paper will describe in detail this unique modelling capability and its application, including riser recoil analysis.
Additionally, accurate modelling of the wellhead, conductor/casing and the surrounding soil structure is crucial in order to accurately predict bending loads experienced in this region. This includes modelling individual wellhead sections (high pressure housing, low pressure housing and tapered sections) and multi-pipe structures for conductor/casing sections (including cement layers). The advanced soil modelling includes the capability to specify different soil types at different depths. This paper will describe in detail these advanced modelling capabilities.
The detailed tensioner modelling capability represents a highly advanced technical and innovative development and is fundamental to providing a realistic recoil analysis capability. The advanced wellhead and casing modelling allows for accurate prediction of the stresses experienced in this critical region and accurate determination of the fatigue lives of these components. This paper will demonstrate how all of these advanced modelling capabilities can be used to accurately model deepwater drilling risers and provide increased confidence in conducting drilling operations in the harshest of environments.