bluuebunny/crossref_metadata_2025_split huggingface dataset:
Considering multiple methods for differentiating conceptually close constructs: Examples from the field of positive psychology
Authors: Hill Patrick L. , Allemand Mathias , Burrow Anthony L. 
Published: September 2018

AbstractThe field of positive psychology has sparked significant interest for researchers, in part given the apparent potential for individuals higher on “positive” dispositions to experience better health and well‐being. However, as the field has grown, so too have the number of conceptually similar dispositions identified by researchers as important to study. As such, there is an increasing need for researchers to understand whether and how conceptually similar “positive” dispositions are actually unique, an issue that may not be unique to positive psychology but has worsened with the field's prominence. The current manuscript provides a roadmap for one approach to differentiating conceptually close constructs in psychology, with examples couched within positive psychology. We will discuss the importance of combining quantitative and qualitative inquiries, as well as the adoption of techniques from multiple psychology disciplines, in order to better distinguish characteristics frequently studied in positive psychology.
Validation of a diagnostic tool for the diagnosis of lumpy skin disease
Authors: Mwanandota Julius J. , Macharia Mercy , Ngeleja Chanasa M. , Sallu Raphael S. , Yongolo Mmeta G. , Mayenga Charles , Holton Timothy A. 
Published: September 2018

BackgroundLumpy skin disease (LSD) is caused by LSD virus which is a member of the Capripoxvirus (CaPV) genus. Although PCR provides for a rapid and sensitive diagnosis, it has limited use due to its complexity in terms of cost, time and equipment. Loop‐mediated isothermal amplification (LAMP) is a simple, specific and cost‐effective method with a diagnostic accuracy similar to PCR.Objectives/HypothesisTo compare the detection rate (DR) of two LAMP assays versus PCR for the detection of CaPV.AnimalsThis study used 105 apparently health animals (AHA) and 59 clinically sick animals (CSA).Methods and materialsPCR and LAMP assays (LAMP1 and LAMP 2) were compared for detection of CaPV from AHA and CSA using blood and tissue samples. The detection was confirmed by sequencing of PCR positive samples. Analytical sensitivity and specificity of LAMP assays also were assessed.ResultsThe DR in CSA was 13.6% for PCR whereas for LAMP it was 39.0% and 25.4% for LAMP 1 and 2 methods, respectively. In AHA, the LAMP assay DR was 14.3% and 1.9% for LAMP 1 and 2, respectively. Phylogenetic tree analysis confirmed the identity of CaPV. Analytic sensitivity showed a detection limit of 8 copies/μL. The analytic specificity test showed no cross detection with other infectious agents.Conclusion and clinical importanceGood sensitivity and specificity results for LAMP assay support its application in the routine diagnosis of LSD, whereas its ability to detect LSDV in apparently healthy animals shows its usefulness in identifying populations at risk of LSD.
Numerical Analysis of Steep Wave-Induced Seabed Response and Liquefaction Around Gravity-Based Offshore Foundations
Authors: Li Yuzhu , Ong Muk Chen , Gudmestad Ove Tobias , Hjertager Bjørn Helge 
Published: September 2018

Gravity-based offshore foundations generally consist of a bottom slab and one or more cylindrical shafts on top of it. The geometry of the structure can strongly affect the flow pattern, dynamic wave pressure and further soil response and the liquefaction risk in the vicinity of the foundation. In this work, gravity-based foundations with bottom slabs of cylindrical shape and hexagonal prismatic shape are investigated. An integrated wave-structure-seabed interaction model applied in this work is developed in Open-FOAM, incorporating a nonlinear wave solver, a linear elastic structure solver and an anisotropic Biot’s poroelastic soil solver consisting of consolidation and liquefaction modules.
Soil consolidation behavior in the presence of the foundations is investigated. It is found that the corners of the hexagonal foundation cause stress concentration in the soil. Therefore the initial effective stress around the hexagon corners is relatively high. Then, fully nonlinear waves modelled by fifth-order stream functions are simulated. Wave-induced pressure distributions and momentary liquefaction depths around the foundations are predicted.
Damage Detection of Offshore Platform Mooring Line Using Artificial Neural Network
Authors: Sidarta Djoni E. , O’Sullivan Jim , Lim Ho-Joon 
Published: September 2018

Station-keeping using mooring lines is an important part of the design of floating offshore platforms, and has been used on most types of floating platforms, such as Spar, Semi-submersible, and FPSO. It is of great interest to monitor the integrity of the mooring lines to detect any damaged and/or failures.
This paper presents a method to train an Artificial Neural Network (ANN) model for damage detection of mooring lines based on a patented methodology that uses detection of subtle shifts in the long drift period of a moored floating vessel as an indicator of mooring line failure, using only GPS monitoring. In case of an FPSO, the total mass or weight of the vessel is also used as a variable. The training of the ANN model employs a back-propagation learning algorithm and an automatic method for determination of ANN architecture.
The input variables of the ANN model can be derived from the monitored motion of the platform by GPS (plus vessel’s total mass in case of an FPSO), and the output of the model is the identification of a specific damaged mooring line. The training and testing of the ANN model use the results of numerical analyses for a semi-submersible offshore platform with twenty mooring lines for a range of metocean conditions. The training data cover the cases of intact mooring lines and a damaged line for two selected adjacent lines.
As an illustration, the evolution of the model at various training stages is presented in terms of its accuracy to detect and identify a damaged mooring line. After successful training, the trained model can detect with great fidelity and speed the damaged mooring line. In addition, it can detect accurately the damaged mooring line for sea states that are not included in the training. This demonstrates that the model can recognize and classify patterns associated with a damaged mooring line and separate them from patterns of intact mooring lines for sea states that are and are not included in the training.
This study demonstrates a great potential for the use of a more general and comprehensive ANN model to help monitor the station keeping integrity of a floating offshore platform and the dynamic behavior of floating systems in order to forecast problems before they occur by detecting deviations in historical patterns.
Optimized Bolt Tightening Sequences in Bolted Joints Using Superelement FE Modeling Technique
Authors: Coria Ibai , Martín Iñigo , Bouzid Hakim , Heras Iker , Aguirrebeitia Josu 
Published: September 2018

A lot of effort is put to achieve bolt preload uniformity during the assembly process of offshore bolted joint connections resulting in potentially high economic costs and project delays. The complexity of this operation is due to the effect of the elastic interaction between the different joint elements which causes load variations of adjacent bolts whenever a bolt is tightened. As a consequence, it is difficult to achieve a uniform target load in the bolts.
In order to avoid this phenomenon, tightening sequences of a large number of passes are usually carried out until a uniform target load is achieved. This solution is neither practical nor efficient when treating hundreds or even thousands of bolted joints due to the large assembly time needed. Several methods were developed to study the effect of the elastic interaction and minimize the assembly time. These methods usually predict the loss of load of every bolt during the tightening sequence, and thus calculate the tightening loads that will provide a uniform final load at the end of the sequence. As a result, an optimized tightening sequence is achieved, which provides a uniform final load distribution in only one or two tightening passes. However, several complex and costly analyses are previously necessary for such purpose.
Based on these traditional methods, this paper presents a new and more efficient optimization methodology to achieve assembly bolt load uniformity. The method is based on the use of superelement technique and is capable of producing similar results with computational costs reduced by 30 times as compared to the more conventional Finite Element (FE) modeling. The results were satisfactorily validated with the latter as well as with tests conducted on a NPS 4 class 900 bolted joint.
Drilling Riser Disconnection Challenges in Ultra-Deep Water
Authors: Diezel Alexandre , Venero Germain , Gomes Victor , Muniz Leandro , Fachini Rafael , Corrignan Hugues 
Published: September 2018

With the extension of the offshore drilling operations to water depths of 10,000 ft and beyond, the technical challenges involved also increased considerably. In this context, the management of the riser integrity through the application of computational simulations is capital to a safe and successful operation — particularly in harsh environments. One of the main challenges associated with keeping the system under safe limits is the recoil behavior in case of a disconnection from the well. The risk that an emergency disconnect procedure can take place during the campaign is imminent, either due to failure of the dynamic positioning system or due to extreme weather in such environments.
Recent work [1] in the field of drilling riser dynamic analysis has shown that the recoil behavior of the riser after a disconnection from the bottom can be one of the main drivers of the level of top tension applied. Tension fluctuations can be very large as the vessel heaves, especially in ultra-deep waters where the average level of top tension is already very high.
In order to be successful, a safe disconnection must ensure that the applied top tension is sufficient for the Lower Marine Riser Package (LMRP) to lift over the Blow-Out Preventer (BOP) with no risk of interference between the two. This tension should also not exceed a range in which the riser will not buckle due to its own recoil, that the telescopic joint will not collapse and transfer undesirable loads onto the drilling rig or that the tensioning lines will not compress. A good representation of such behavior in computational simulations is therefore very relevant to planning of the drilling campaign.
A case study is presented herein, in which a recoil analysis was performed for a water depth of 11,483ft (3,500m). Numerical simulations using a finite element based methodology are applied for solving the transient problem of the riser disconnection in the time domain using a regular wave approach. A detailed hydro-pneumatic tensioning system model is incorporated to properly capture the effect of the anti-recoil valve closure and tension variations relevant during the disconnection.
A reduction of conservativism is applied for the regular wave approach, where the maximum vessel heave likely to happen in every 50 waves is applied instead of the usual maximum in 1000 waves approach. ISO/TR 13624-2 [4] states that using the most probable maximum heave in 1000 waves is considered very conservative, as the event of the disconnection takes place in a very short period of time.
The challenges inherent to such an extreme site are presented and conclusions are drawn on the influence of the overall level of top tension in the recoil behavior.
Development and Testing of a Friction-Based Post-Installable Fiber-Optic Monitoring System for Subsea Applications
Authors: Seaman Calvin H. , Wilson J. Conrad , Kipp Robert M. , Hedengren John D. , Tang Henry H. , Bentley Nicole L. , Le Suy Q. , Brower David V. 
Published: September 2018

This paper continues to document the design, development, and test of a friction-based (non-adhesive) post-installable fiber-optic strain sensing system for oil and gas applications — especially those that require deployment on existing subsea structures. (Ref: OMAE2017-61494 Development and Testing of a Friction-Based Post-Installable Sensor for Subsea Fiber-Optic Monitoring Systems [1]). The prototype fiber-optic monitoring system collects a wide range of real-time data, which can be used to determine structural loading, fatigue, temperature, pressure, and flow assurance on operational platforms.
The primary challenge of a post-installed instrumentation monitoring system is to ensure secure coupling between the sensors and the structure of interest for reliable measurements. Friction-based coupling devices have the potential to overcome installation challenges caused by marine growth and soil contamination on subsea structures, flowlines, or risers. This particular design solution is compatible with structures that are suspended in the water column and those that are resting on the seabed. In addition, the system can be installed by commercial divers in shallow depths or by remotely operated vehicles in deep-water applications.
Operational limitations of the initial design concept were identified in the previous series of tests (2016–2017), and several innovative enhancements have been implemented which resulted in significant improvements in sensor system coupling and strain measurement correlation with traditional strain measuring devices. This paper provides a summary of the notable prototype design changes, full-scale test article buildup, and detailed performance data recorded during tension and compression loading that simulated representative offshore conditions. The test results were positive and demonstrated the effectiveness of the design enhancements. Compromises made during mounting of the sensing elements resulted in better performance in tension than compression. These effects are well understood and are fully discussed, and do not influence the viability of the design changes.
This study is part of a continuing collaboration between the Houston-based NASA-Johnson Space Center and Astro Technology, Inc. within a study called Clear Gulf. The primary objective of the Clear Gulf study is to develop advanced instrumentation technologies that will improve operational safety and reduce the risk of hydrocarbon spillage. NASA provided unique insights, expansive test facilities, and technical expertise to advance these technologies that would benefit the environment, the public, and commercial industries.
Real Sea Testing of a Small Scale Weptos WEC Prototype
Authors: Kofoed Jens Peter , Tetu Amelie , Ferri Francesco , Margheritini Lucia , Sonalier Nathan , Larsen Tommy 
Published: September 2018

The Weptos wave energy converter (WEC) is Danish concept that has been investigated during the last decade in laboratory test campaigns. It is an A-shaped floating structure that absorbs wave energy through multiple wave absorbing bodies. These bodies are rotors, with their shape inspired by the Salter duck, of which its high efficiency has been proven already back in the 1970’s. The Weptos WEC has the ability to maximise power absorption in operational sea states and minimize structural loads in extreme conditions through adjustment of its width.
Launch of a small scale real sea prototype of the Weptos WEC was done in July 2017, with a location in Lillebælt between Jylland and Fyn in Denmark, north of the small island Brandsø, at a water depth of 10 m. The paper contains a detailed description of the prototype and its instrumentation, along with the test planning and preliminary data analyses for the evaluation of the device characterization.
Qualification of Sealing System for Flexible Pipes Using a Self-Energized Gasket
Authors: Wang Christian , Halsteen Martin , Ries Jesper 
Published: September 2018

In order to meet higher technical demands designing flexible pipes at higher pressures and higher temperatures for deeper water depths NOV has introduced and qualified a new sealing system that is self-energized. The sealing material has been qualified and tested in different fluids. The sealing system has shown good functionality at higher pressures as well as at lower pressures.
The qualification of the sealing system has been based on multiple full-scale and mid-scale tests according to Recommended Practice API 17B and small-scale tests on the elastomer material including long-term ageing tests and rapid gas decompression tests in high pressure CO2 up to 900 bar.
The recommendations of RP API 17B used in the industry has its limitation with regards to qualification of a new sealing system. This paper gives an overview how to qualify a new sealing system on an existing product range achieving different technology readiness levels according to Recommended Practice API 17N from TRL1 up to TRL5. TRL5 covers system integration testing by full-scale testing of flexible pipes such as burst test, tension-pressure test, tension-tension test and deep immersion performance test. All qualification tests have been witnessed by a third-party Bureau Veritas and the enhanced sealing system has archived a TRL5 statement within its current design envelope.
Scale Effects on Ship Maneuverability Using RANS
Authors: Araki Motoki 
Published: September 2018

Predicting ship maneuverability is one of the important topics in ship engineering. However because of the huge difference between model and full scale Reynolds number (Re), it is almost impossible to predict full scale ship maneuverability using conventional methods such as model test. On the other hands, with the developments of computational technologies and computational fluid dynamics (CFD) techniques, CFD simulations are widely applied on ship maneuvering problems (e.g. Stern et al., 2011). Moreover some of the researchers start the CFD simulation with full scale Re especially on propulsion problems (e.g. Tezdogan et al., 2015) which showing reasonable results.
Therefore, in this paper, captive maneuvering simulations (rudder angle test) in model/full scale Re on KVLCC2 are carried out using Reynolds-averaged Navier–Stokes (RANS) solver NAGISA (Ohashi et al., 2014) with the overset gird method UP_GRID (Kodama et al., 2012). And the results between model and full scale simulations are compared in maneuvering coefficients and flow field to reveal the scale effect on ship maneuverability.
Dynamic Positioning Reliability Index (DP-RI) and Offline Forecasting of DP-RI During Complex Marine Operations
Authors: Fernandez Charles , Kumar Shashi Bhushan , Lok Woo Wai , Norman Rosemary , Kr. Dev Arun 
Published: September 2018

The Dynamic Positioning (DP) System is a complex system with significant levels of integration between many sub-systems to perform diverse control functions. The extent of information managed by each sub-system is enormous. The complex level of integration between sub-systems creates more possible failure scenarios. A systematic analysis of all failure scenarios is tedious and for an operator to handle any such catastrophic situation is breath taking. There are many accidents where a failure in a DP system has resulted in fatalities and environmental pollution. Therefore, reliability assessment of a DP system is critical for safe and efficient operation of marine and offshore vessels.
Traditionally, the reliability of a DP system is assessed during the design stage by methodologies such as Failure Mode Effects and Analysis (FMEA), Proving Trials, Hardware In-the Loop (HIL) testing, Site-Specific Risk Analysis, DP capability Analysis and during operation by annual trials to verify functionality. All these methods are time consuming, involving a lot of human effort and notably no analysis of previous accidents are indicated in the reliability assessment. This imposes in-built uncertainty and risk in DP system during operation.
In this paper, a new concept of Dynamic Positioning Reliability Index (DP-RI) is introduced and a state-of-the-art advisory decision making tool is proposed. This tool is developed based on information from various sources including Offshore Reliability Data (OREDA), International Marine Contractors Association (IMCA) Accident database, DP vendor equipment failure databases, DP System supplier’s manuals, previous system level FMEA and HIL testing results, Site specific risk analysis documents, Project design specification and Operator’s operational experiences. Thus, DP-RI addresses the pitfalls of existing reliability assessment methods and will be an efficient tool in reducing the number of DP-related accidents.
Insights Into Compaction Grouting for Offshore Pile Foundations
Authors: Geißler Peter , Cuéllar Pablo , Hüsken Götz , Kühne Hans-Carsten , Baeßler Matthias 
Published: September 2018

The authors are currently investigating the possibility to apply compaction grouting for offshore pile foundations (Jacket piles as well as monopiles) as a possible retrofitting technique for an optimised foundation concept. In this research project, we are developing a design approach aiming to predict the ideal amount and properties of a grout for a specific soil situation and desired improvement of pile bearing capacity after installation and during service time. Both numerical and experimental tests have been carried out to investigate the injection process during which a highly viscous grout is injected into the soil under high pressure to displace and compact the surrounding soil without fracturing it. The implicit Material Point Method (MPM) based on a mixed formulation is the numerical technique chosen to deal with the expected large deformations and the arbitrary shape of the developing grout bulb. The usage of MPM prevents both the need of remeshing and the numerical instability induced by extensive mesh distortion. For validation with experimental results, we have constructed a testing chamber with one transparent sidewall. This chamber enables us to observe the injection process directly at the transparent vertical window and to measure the in-plane soil displacements and strains by means of the Digital Image Correlation (DIC) technique.
The results already reveal the interrelation of soil and grout properties for a successful usage of this common ground improvement technique.
Effect of Tension on Collapse Performance of Flexible Pipes
Authors: Miyazaki Marcelo , Paumier Laurent , Caleyron Fabien 
Published: September 2018

This paper investigates the effect of tension on collapse performance of flexible pipes.
In the design of flexible pipelines for offshore field developments, one of the failure modes being associated with external pressure and bending loadings is the hydrostatic collapse. In accordance with standards, TechnipFMC methodology for flexible pipe collapse resistance determination ensures a robust design. The model has an analytical basis, leading to a fast and straightforward use. It has been validated with more than 200 tests performed on all possible pipe constructions on straight and curved configurations.
TechnipFMC and IFP Energies nouvelles have also developed and improved over the past few years a Finite Elements Model dedicated to flexible riser studies. It takes full advantage of the structure periodicities such that a whole riser can be studied with a short length and low CPU cost model associated to specific periodicity conditions. The model is able to represent bent risers in various configurations (bending cycles, internal and external pressure, axial tension, torsion) and has been used for collapse prediction of flexible risers under tension. Additionally, a specific test protocol has been developed to be able to carry out a collapse test associated to tension.
The purpose of this paper is to present the collapse test result, the specific development of the model for collapse and tension and the corresponding calculations performed with the Finite Elements Model on several structures, demonstrating that there is no negative influence of tension on collapse mode. It also gives a better understanding on the interaction between tension in the armor layers and collapse phenomenon.