bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Wave-Current Interaction on Floating Bodies
Authors: Hermundstad Elin Marita , Hoff Jan Roger , Stansberg Carl Trygve , Baarholm Rolf 
Published: October 2016

Wave-current interaction effects may significantly influence the mean wave drift forces on a structure as well as the motion responses and wave elevation around the structure. Additionally, the drift force may be used to estimate the wave drift damping of a moored structure.
A new numerical potential theory code for industry applications (MULDIF) has been recently developed, where the hydrodynamic interaction between waves and current of arbitrary direction with large volume structures is consistently included. The code also handles multiple bodies and finite water depth including wave-current interaction effects. The aim has been to create a robust and easy-to-use practical tool.
Initial validation studies against model tests have been conducted. The numerical results show a strong heave-pitch coupling due to the presence of the current. Preliminary results for a semi-submersible show good agreement for the motions provided that the mooring used in the model tests are accounted for. The free surface elevation around the semi-submersible is presented in contour plots.
CFD Reproduction of Model Test Generated Extreme Irregular Wave Events and Nonlinear Loads on a Vertical Column
Authors: Pakozdi Csaba , Östman Anders , Bachynski Erin E. , Stansberg Carl Trygve 
Published: October 2016

Recently, a method for numerical reproduction of measured irregular wave events has been developed. The measured motion of the wave maker flaps defines the wave kinematics at the boundary of the numerical simulation in order to generate the waves as described in (Pakozdi, Kendon, & Stansberg, 2011) and (Ostman, Pakozdi, Stansberg, Fagertun, & Vestbostad, 2015).
When such data are not available, the control signal of the wave maker can, instead, be generated from a given free surface elevation following the same procedure as in model tests. Following this procedure automatically gives the possibility to subsequently reproduce the numerical wave experimentally using the obtained control signal.
The latter procedure is applied to a model test case with extreme irregular wave events and resulting nonlinear global wave loads on a vertical cylinder (Stansberg, 1997), with the focus on higher-order ringing excitation. The purpose of the investigation is two-fold: 1) to validate the wave reconstruction procedure, and 2) to validate the resulting CFD ringing loads with the given waves. The results show generally good agreement both in the waves and in the loads; discrepancies found in the loads are considered to be mainly originating from corresponding uncertainties in the wave reconstruction. Wave breaking may be one source of uncertainty.
Comparison of Global Response of a 3-Span Floating Suspension Bridge With Different Floater Concepts
Authors: Fredriksen Arnt G. , Bonnemaire Basile , Lie Halvor , Munkeby Jan , Nesteby Anders , Buckholm Petter , Tan Xiang 
Published: October 2016

Several bridge concepts for crossing deep and wide fjords along E39 at the west coast of Norway have been developed the last years. One of the most challenging fjord crossing is suspected to be the crossing of Sulafjord, 3 to 5 km wide, 400 m deep and with presence of relatively large swell waves.
A suspended floating bridge concept is a marine slender flexible structure with large volume elements as floating support. The hydrodynamic actions on the floaters is an additional excitation compared to a traditional suspended bridge with fixed piles. In order to assess the effects of this excitation, it is important to consider the whole system and accurate hydrodynamic methods.
While the superstructure type — a suspended bridge — is set, the type of floating foundation remains open. From the offshore experience, it is seen that different types of floaters are used for moored platforms, and these floaters have significantly different characteristics in particular with regards to wave response and stability.
The design requirements for an offshore platform differ greatly from those of a suspended floating bridge crossing a fjord. For a floating bridge, the payload requirements are not the most challenging, while it is more difficult to limit the tilting and dynamic excitation of the tower (mounted on the floaters). The bridge beam is suspended at the top of the towers and will respond to any excitation due to motions of the tower tops.
A global numerical model of the bridge to simulate nonlinear dynamic response due to regular and irregular waves is built. The numerical model of the bridge is simplified from a structural point of view. However, the dynamical properties and eigenmodes are verified against a more detailed structural model. Together with a 50-year long continuous time-series of wind, wind waves and swells a study of the bridge operability and extreme responses for different floater concepts is conducted.
Normally the design phase should aim at avoiding any natural periods to fall within the wave frequency domain. This seems difficult for the proposed 3-span floating suspension bridge, instead solutions to minimize the excitation from waves for wave periods around the given bridge eigenperiods are sought.
Advanced Finite-Element Modeling for Creep Simulation on Flexible Pipe Pressure Sheath
Authors: Naturel Jérôme , Epsztein Thomas , Gavouyère Thierry 
Published: October 2016

Unbounded Flexible pipe used for offshore fields development are usually composed of different layers of polymer and steel, each layer having a specific function during the product service life. This multi-layer characteristic enables to tailor the cross-section of the pipe to meet project-specific requirement, and optimize the cost of the product for each application. In particular, the main function of the thermoplastic pressure sheath is to guaranty the sealing of the product. The material and the thickness of this pressure sheath mainly depend on the pressure and temperature of the bore, and the design choice is driven by the creeping of the sheath in the interstices of the pressure vault: it must be limited with regard to sheath thickness reduction, as per API17J design requirement.
Consequently, when developing new material for pressure sheath application, the early prediction of the creep performance over the full range of the targeted application is crucial. For this reason, before any full-scale test, a test campaign is required to evaluate the creeping of the material on small-scale material sample. In this development context, the use of advanced finite-element simulation for predicting the creeping behavior is quite useful to amplify the benefit of tests campaign results, and to give additional information on material performances. As far as the modelling is validated by correlation with small-scale tests, the numerical tool is used to multiply virtual creep tests configurations.
This paper will focus on the numerical challenges for developing such creeping simulation, based on ABAQUS commercial software. Firstly, the identification of the viscoelastoplastic parameters for polymer material law will be presented. This material law is a nonlinear viscoelastoplastic model consisting of multiple networks connected in parallel. The number of parameters of such law is not limited, but a compromise between law precision and identification robustness must be found. Then, the correlation process between small-scale test and finite-element results will be detailed. In particular, the influence of the experimental protocol has to be determined. Finally, a sensitivity study of the most influent parameters, based on parametric FEA model, will be presented to highlight the benefice of such model. The benefice of such model does not only consist on correlation with small-scale test. As the material modeling is intrinsic, it is also possible to use the same law for studying the creep behavior on very different geometrical configurations.
A Synthesis Model for FLNG Design
Authors: Vieira Daniel Prata , Lavieri Rodrigo Sauri , Rocha Thiago Peternella , Dotta Raul , Rampazzo Fabiano , Nishimoto Kazuo 
Published: October 2016

The increasing demand for natural gas is encouraging the development of novel floating units’ designs, capable of processing large quantities of hydrocarbon. These units called FLNG (Floating Liquefied Natural Gas) are facilities that produce, process and store liquefied natural gas (LNG) offshore. Once the topside and tanks of a FLNG are larger and more complex than the regular FPSO vessels, a design process considering these particularities must be used.
Once just few FLNG units are under construction and under design and not yet in operation, the information on the design first stages is poor. It is difficult to obtain a first hull sizing without taking in account the complexity mentioned above.
Thus, a set-based approach that works with sets of possible solutions that are analyzed and compared using a merit function in order to select the best and feasible solutions was used.
However, to produce a sufficiently large family of solutions, which includes most of the solution space, either the solution descriptions or the models must be simplified. From the computational point of view, the analyses of a family of design solutions basically relies on an initial parameterization of the object and a set of mathematical models that, as a group, will be referred as synthesis model. Additionally, some restrains are also applied to eliminate unfeasible solutions. The output of the synthesis model is a set of performance quantities that will be used to rank the solutions.
This design approach is particularly useful to deal with project trade-offs and to optimize multiple characteristics. Optimal solutions belongs to a surface (or a hyper surface) called Pareto boundary. This paper aims to achieve a platform design capable of producing, storing and offloading liquefied natural gas. It must safely survive under environmental conditions of Santos Basin in São Paulo, Brazil. In the same way, the design should guarantee the shortest downtime as well as keep costs, of acquisition and operation, as low as possible. Each of these characteristics must be quantified to allow a ranking of the generated solutions through an objective function.
Capacities, production rates, equipments, load distribution, environmental actions, stability, sea keeping and structural design estimates are the major areas to consider and will be related to one or more mathematical models, constraint and objective functions. The work will present a general overview of each model separately and how they work together, as well as examples of solutions and analyses depending on the input values.
It must be clear that this approach is applicable just in the early stages of design to obtain the first hull sizing. After that it is necessary to fall back on the traditional iteration process to rely in a feasible design.
Vortex-Induced Vibrations of a Riser With Design Variations
Authors: Zueck Robert F. 
Published: October 2016

As meta-stable motions transverse to fluid flow in slender bluff-bodied structures, Vortex-Induced Vibrations (VIV) are mostly determined by three-dimensional (3D) geometric and relativistic changes that evolve in the structure. Simplistic models of the structure ignore these key physical principles.
In a 2014 OMAE paper, we introduced the key physical concepts for simulating VIV in a horizontal-oriented slender structure (pipeline). In a 2015 OMAE paper, we re-oriented the same structure vertically to simulate VIV in a vertical riser.
In this paper, one or more of the following variations in the vertically-oriented riser will be made, in order to judge the physical effect each variation has on the character and distribution of VIV along the riser:
• Cyclically move the upper end of the vertical riser
• Change into an S-shaped riser by adding weight/buoyancy
• Disconnect the lower end of the S-shaped riser
The simulations help show and reinforce the following mechanical concepts of VIV
• How gravity and fluid drag evolves a 3D shape in the riser
• How this shape creates specific structural flexibilities
• How these flexibilities set the stage for specific VIV
• How tension and end conditions are vital to VIV behavior
Re-Evaluation of Suction Anchor Holding Capacity Based on Back Analysis of Undrained Shear Strength
Authors: Shin Yunsup , Langford Thomas , De Sordi Jerome 
Published: October 2016

Suction anchors are used within mooring systems for a range of deep water floating structures. The number of suction anchor systems has increased rapidly over the last two decades due to ease of installation and a well-defined design approach. As with other offshore installations, anchor systems may be subjected to re-assessment during their operational lifetime, due to changes in loading, codes or other issues. Such assessment was performed recently for a floating storage unit (FSU) presently in service in the Norwegian Sea, where the geotechnical design of the anchors was re-evaluated.
The re-assessment of this storage unit allowed for a number of changes compared to the original design, including updated loads and load histories as well as changes to the safety factors. The geotechnical aspects of the design were also updated, including more refined analyses and a detailed review of the design soil profiles based on back-analysis of installation data.
This paper presents the work done related to the geotechnical holding capacity of the anchors during the assessment project. The work performed highlights the benefit of efficient FE analysis and a thorough evaluation of the soil properties and engineering behaviour.
Optimization of a Parametric FLNG in Finite Water Depth
Authors: Guha Amitava , Falzarano Jeffrey 
Published: October 2016

Ultra large vessels such as recently engineered FPSOs and FLNG terminals require careful consideration of the effect of water depth in determining their motion characteristics. An efficient numerical implementation of the finite depth Green function, utilizing a series and integral form, has been developed. This is then incorporated in a three dimensional frequency domain panel method program capable of considering forward speed effects. The effect of water depth on the first and second order wave exciting forces and induced motions are studied.
An optimization framework is then developed combining an automated parametric FLNG hull form, the aforementioned in-house developed hydrodynamic analysis tool and an evolutionary optimization solver. In this paper, the principal methodologies used in the development of the finite depth Green function, solving the boundary value problem and key learning from the FLNG optimizations will be discussed.
Verification of Riser Load Stacked on Stanchion Induced by Self Weight and Hull Acceleration
Authors: Kim So-Yoon , Choi Ki-Sub , Kim Myung-Hyun 
Published: October 2016

Recently offshore installations for the development of gas and oil resources have moved toward the deeper sea and harsher environment. In this regard, there are increasing operational demands for offshore structures performing in depth with long distance transportation. Drill ships are one of the representative structures commonly employed for the development of energy resources in deep sea. However, these drilling systems are exposed to the various loadings and harsh environment. Therefore, current design code and standards are very conservative to take account of such conditions. The riser stanchions for the staking the riser are one of the structure that installed on the riser deck platform of drill ship. In transit or operating conditions, the riser load is applied to the stanchion. Therefore, the required strength of stanchion enough to withstand the riser loads and should be designed to meet owner and classification requirements. However, the currently practice design loads, which has been widely used in the shipyard and manufacture industries are too conservative resulting in excessive structural weight. In this regard, the purpose of this study is to propose a rational calculation procedure for the design of cost effective and lightweight stanchion structures.
This study used a pyramid stacking type of arrangement for the investigation of the effects of stanchion by riser self-weight and hull acceleration. First, the riser loads based on the current conventional design practice is compared with the results obtained by non-linear finite element analysis. In the finite element simulation, contact and damping conditions of stacked risers are explicitly considered. Second, the calculation of riser loads in transverse direction is not easy due to the difficulty associated with considering transverse hull acceleration. Therefore, a new design guideline is presented in a strength calculation of the stanchion structure against to the estimated design loads.
Methodology for Definition of New Sectors for DP Assisted Offloading Operations in Spread Moored Platforms
Authors: de Barros Orsolini Ana Luisa , Tannuri Eduardo Aoun , Santana Castelpoggi Felipe , Takashi Yuba Douglas Gustavo 
Published: October 2016

This project defines a methodology for analyzing the proposition of expanding the operational sector of DP shuttle tankers in offloading operations in Spread Moored Platforms and still guaranteeing the operations’ safety.
The methodology consists at first in an evaluation of the reduction of the operation’s downtime as a function of sector angle increase by performing static analysis. These simulations are calibrated and validated by performing fast time dynamic simulations. Then, a Preliminary Risk Analysis is made to assess the potential hazards associated with the operation on the new expanded sector and, if necessary, some quantitative analyses take place. Finally, the methodology proposes that real time simulations are performed so that most critical conditions are recreated in the presence of an experienced Captain so he can give his opinion on how safe the operation would be.
Evaluation of the Carba NP Test in Oregon, 2013
Authors: Morey Karim E. , Vega Robert , Cassidy P. Maureen , Buser Genevieve L. , Rayar Jaipreet K. , Myers Jeffrey A. , Weissman Scott J. , Beldavs Zintars G. , Pfeiffer Christopher D. 
Published: October 2016

ABSTRACT

Carbapenem-resistant
Enterobacteriaceae
(CRE) are an urgent public health threat. We evaluated the capacity of the Carba NP test to detect carbapenemase production in 206 isolates: 143
Enterobacteriaceae
identified by Oregon's CRE surveillance program in 2013 and 63 known carbapenemase-positive organisms. Overall, test sensitivity and specificity were 89% (59/66 isolates; 95% confidence interval [CI], 81 to 97%) and 100% (140/140 isolates; 95% CI, 98 to 100%), respectively. All KPC, NDM-1, VIM, and IMP producers but no (0/7 isolates) OXA-48-like strains were Carba NP positive prior to a
post hoc
protocol modification. We subsequently incorporated Carba NP into Oregon's CRE screening algorithm.
Mitogen-Activated Protein Kinase 2 Signaling Shapes Macrophage Plasticity in Aggregatibacter actinomycetemcomitans-Induced Bone Loss
Authors: Herbert Bethany A. , Steinkamp Heidi M. , Gaestel Matthias , Kirkwood Keith L. 
Published: October 2016

ABSTRACT

Aggregatibacter actinomycetemcomitans
is associated with aggressive periodontal disease, which is characterized by inflammation-driven alveolar bone loss.
A. actinomycetemcomitans
activates the p38 mitogen-activated protein kinase (MAPK) and MAPK-activated protein kinase 2 (MK2) stress pathways in macrophages that are involved in host responses. During the inflammatory process in periodontal disease, chemokines are upregulated to promote recruitment of inflammatory cells. The objective of this study was to determine the role of MK2 signaling in chemokine regulation during
A. actinomycetemcomitans
pathogenesis. Utilizing a murine calvarial model,
Mk2

+/+

and
Mk2
−/−
mice were treated with live
A. actinomycetemcomitans
bacteria at the midsagittal suture. MK2 positively regulated the following macrophage RNA:
Emr1
(F4/80),
Itgam
(CD11b),
Csf1r
(M-CSF Receptor),
Itgal
(CD11a),
Tnf
, and
Nos2
. Additionally, RNA analysis revealed that MK2 signaling regulated chemokines CCL3 and CCL4 in murine calvarial tissue. Utilizing the chimeric murine air pouch model, MK2 signaling differentially regulated CCL3 and CCL4 in the hematopoietic and nonhematopoietic compartments. Bone resorption pits in calvaria, observed by micro-computed tomography, and osteoclast formation were decreased in
Mk2
−/−
mice compared to
Mk2

+/+

mice after
A. actinomycetemcomitans
treatment. In conclusion, these data suggest that MK2 in macrophages contributes to regulation of chemokine signaling during
A. actinomycetemcomitans
-induced inflammation and bone loss.
Serine-Aspartate Repeat Protein D Increases Staphylococcus aureus Virulence and Survival in Blood
Authors: Askarian Fatemeh , Uchiyama Satoshi , Valderrama J. Andrés , Ajayi Clement , Sollid Johanna U. E. , van Sorge Nina M. , Nizet Victor , van Strijp Jos A. G. , Johannessen Mona 
Published: October 2016

ABSTRACT

Staphylococcus aureus
expresses a panel of cell wall-anchored adhesins, including proteins belonging to the microbial surface components recognizing adhesive matrix molecule (MSCRAMM) family, exemplified by the serine-aspartate repeat protein D (SdrD), which serve key roles in colonization and infection. Deletion of
sdrD
from
S. aureus
subsp.
aureus
strain NCTC8325-4 attenuated bacterial survival in human whole blood
ex vivo
, which was associated with increased killing by human neutrophils. Remarkably, SdrD was able to inhibit innate immune-mediated bacterial killing independently of other
S. aureus
proteins, since addition of recombinant SdrD protein and heterologous expression of SdrD in
Lactococcus lactis
promoted bacterial survival in human blood. SdrD contributes to bacterial virulence
in vivo
, since fewer
S. aureus
subsp.
aureus
NCTC8325-4 Δ
sdrD
bacteria than bacteria of the parent strain were recovered from blood and several organs using a murine intravenous infection model. Collectively, our findings reveal a new property of SdrD as an important key contributor to
S. aureus
survival and the ability to escape the innate immune system in blood.