bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design Under Arctic Conditions: A Summary of the Arctic Materials Project Guideline
Authors: Horn Agnes Marie , Østby Erling , Akselsen Odd , Hauge Mons 
Published: September 2018

The main goal of the 10 years Arctic Materials KMB project run by SINTEF (2008–2017) and supported by the industry is to establish criteria and solutions for safe and cost-effective application of materials for hydrocarbon exploration and production in arctic regions. The objective of the arctic materials project guideline (PG) is to assist designers to ensure safe and robust, yet cost-effective, design of offshore structures and structural elements in arctic areas through adequate material testing and requirements to material toughness. It is well known that when the temperature decreases, steel becomes more brittle. To prevent brittle fracture in the Arctic, the structure needs adequate toughness for the loading seen at low temperatures. None of the common offshore design codes today consistently address low temperature applications. In this respect, arctic areas are defined as minimum design temperatures below what current international standards have considered per today, i.e. −10 °C to −14°C. For practical applications, the PG defines arctic areas as minimum design temperature lower than −10 °C.
It is acknowledging that design standards to a certain degree are based on operational and qualitative experiences gained by the offshore industry since the 1970’s. However, for arctic offshore facilities, limited operational experiences are gained by the industry. The basis of the guideline is that safe and robust design of structures and structural elements are ensured by combining standard industry practice today with learnings and findings from the 10 years Arctic Materials project.
This paper is concerned with the rationale behind the material and test requirements provided in the arctic material guideline. The material requirements will be discussed in detail with emphasis on toughness requirement, constraint effect, thickness effect, acceptance criteria and material qualification criteria.
Quantifying the Uncertainty of the Crabbing Capability
Authors: Ferrari V. , Kisjes A. , Quadvlieg F. H. H. A. 
Published: September 2018

Crabbing is a critical manoeuvre that requires all of the ship’s propulsors to counteract environmental forces. It is a complex hydrodynamic scenario in which it is difficult to assess the factors, nonetheless the crabbing capability is often calculated by means of simple static calculations which consider only means values. The ship designer or master should instead be aware of how much the crabbing capability can change when the propulsors are less efficient than expected or the wind loads are higher.
The present paper details the application of sensitivity and uncertainty methods to the crabbing manoeuvre of a ship. The objective is to estimate the sensitivity of the main parameters involved in a crabbing calculation and express the results in terms of uncertainty range. To this purpose, first a sensitivity analysis is performed, showing how the maximum sustainable wind speed of a test-case ship varies. The curves derived from this analysis are then used to estimate numerically the relation between wind speed and a variation in each parameter. Typical values of uncertainty of these parameters are presented, and finally the crabbing capability calculated taking into account the uncertainties.
Uncertainties of Ship Speed Loss Evaluation Under Real Weather Conditions
Authors: Prpić-Oršić Jasna , Sasa Kenji , Valčić Marko , Faltinsen Odd Magnus 
Published: September 2018

A correct assessment of the ship speed loss in conditions of exploitation is becoming increasingly important for ship owners as well as ship designers. We are witnessing the increasing concern for the environment and awareness of the necessity to preserve it as much as we could. The ship speed drop in the real environmental conditions can cause the increased fuel consumption as well as increased emissions of CO2 and other GHG (greenhouse gases) from ships. Decrease of the ship speed in real conditions is a consequence of the added resistance due to the impact of weather conditions, i.e. waves and wind, and due to aggravated working conditions of propeller, i.e. engine system. Moreover, the solution estimation of this problem is very affected by human factors. Ship master, concerning for safety, can make a judgment that, under certain adverse weather loads, it is necessary to slow down or change ship’s course to moderate or bypass the worst condition. In addition, the loading condition of the ship is constantly changing which govern the basic parameters of the ship: the mass and mass moment of inertia, draft and trim and, consequently, the ship behavior at sea.
All these parameters affect the assessment of ship speed and it is necessary to be conscious of the intensity of their impact on the final value. At the same time, they cannot be predicted with absolute certainty so the purpose of this analysis is to estimate the impact of weather and operational uncertainties on the actual speed of the ship in real operating conditions.
How to Estimate Performances of Cryogenic Spillage Protection Materials?
Authors: Viale Sebastien 
Published: September 2018

The planned operation of natural gas liquefaction units offshore has raised many new safety issues. Cryogenic spillage is among the most critical as load bearing structures cannot be designed to resist such accidents.
In order to propose better protection at manageable cost, to enhance structural integrity and to lower the risks associated with cryogenic spillage on marine structures, TechnipFMC as FLNG market leader, has run an extensive physical test program to support the development of tailor made numerical modeling tools.
In a first step, numerous protective materials were screened and then tested to assess their performances. We found that all products currently available in the market display limitations. During the test campaign, alternate product designs were investigated to improve structural design and avoid the need for human intervention “Inspection Maintenance and Repair” during service lifetime.
In this paper, a summary of the test campaign and a complete introduction of Series of standard of ISO 20088 will be provided.
A Case Study for an Offshore Structure for Aquaculture: Comparison of Analysis With Model Testing
Authors: Berstad Are Johan , Aarsnes Jan Vidar 
Published: September 2018

This paper presents a case study of a structure of a novel fish farm cage. The “AquaTraz” cage is more similar to structures known to the the oil and gas industry. The cage has the same shape as the normal cages used in the aquaculture industry and can be introduced to existing grid-moorings.
Model testing has been carried out and results from the model test are compared with results from numerical simulations using the tool AquaSim. The response deviating from classic fish farms is shown and what extra considerations that should be carried out for this type of systems compared to classic fish farms is discussed.
Decommissioning of Offshore Monopiles, Occuring Problems and Alternative Solutions
Authors: Hinzmann Nils , Stein Philipp , Gattermann Jörg 
Published: September 2018

The German offshore wind industry has historically grown since the first offshore wind farm (OWF) “alpha ventus” was completed in 2010. Since the end of 2017 a total number of 18 OWF with a capacity of about 5 GW have been operating in the German Exclusive Economic Zone (EEZ) [1]. While the majority of the population and the industry focus on new projects, it appears the life cycle observation and especially the decommissioning phase remain largely unattended. This narrow view can lead to unexpected and expensive consequences in the future. The decommissioning of a complex structure as an offshore wind turbine (OWT) needs to be planned well in advance. There are numerous aspects that make the decommissioning a challenge, such as the federal regulations, the marine environment and the technical limitations of offshore operations.
This article gives an overview of the problematic matter of dealing with monopiles after the predicted lifetime, the geotechnical condition, analyses of the current decommissioning options and identification of issues in regards to the decommissioning method. Furthermore, other promising decommissioning methods for a complete removal of offshore monopiles, such as vibratory extraction, internal dredging, external jet drilling and the use of buoyancy force, are presented and compared concerning a possible combination. Some of the presented methods are highly experimental, others are commonly used in other industries.
Design and Make of a Segmented Ship Model for Vertical Bending Moment Measurement
Authors: Yue Jingxia , Guo Yulong , Peng Lihua 
Published: September 2018

With the development of the large-scale ship, the hull becomes more and more “soft” and “elastic”. Accurate simulation of ship’s hydro-elastic performance through scaled model test plays an important role in structural safety assessment. This paper presents the detail preparation of a segmented model which is used to investigate the vertical bending moment (VBM) for a 260m TEU container ship.
Some innovative concepts were involved in the scaled model design. Firstly, the segmentation of the ship model was based on the hull’s vertical vibration mode for better simulation of the hull’s rigidity distribution. Secondly, the section of the backbone beam was varied by polishing along ship length in order to simulate the varied section modulus of ship hull. Thirdly, new backbone fixed type was carried out by two flange plates for a better wave load transmission.
Besides, some useful techniques were provided, including the model making technique, calibration technique, and backbone system technique. It increases the feasibility of test, at a certain extent. Finally, an overview of the ongoing large scale model test plan and its future development directions is prospected.
Model Scale Testing of the Tupperwave Device With Comparison to a Conventional OWC
Authors: Benreguig Pierre , Murphy Jimmy , Sheng Wanan 
Published: September 2018

A model testing campaign of the Tupperwave device was carried out to prove the working principal and validate a numerical modelling that had previously been developed. An appropriate and challenging scaling method was applied to the floating device to correctly model the air compressibility in the Tupperwave PTO. In parallel, a model scale conventional OWC was also built using the same axisymmetric structure geometry and both devices were tested and compared. The testing showed that the Tupperwave device produced less average useful pneumatic power than the conventional OWC. The primary losses were attributed to pneumatic power dissipation through the valves. The pneumatic power delivered by the Tupperwave device was however significantly smoother.
The paper describes the experimental set-up and the methods used to assess the devices performance. The results provide a direct comparison between the two physical models pneumatic power performances and an in-depth analysis of the valves behaviour is shown.
Nonlinear Lid Technique: Application to Gap and Moonpool Resonance
Authors: Lécuyer B. , Rouault M.-C. 
Published: September 2018

This paper focuses on the implementation of a nonlinear Lid Technique, as done in the software Diodore™. Several dummy plates are used and modelled as mechanical structures with their own degrees of freedom, capable to account for nonlinear damping.
The paper describes first the general equations governing the multi-body sea-keeping model including dummy plate structures, and the expression of the relative quadratic damping. In a second step, examples of applications with gap and moonpool are exposed, demonstrating the capability of the nonlinear Lid Technique with multiple plates to render not only the piston mode, but also the other modes of deformation of the free surface.
Deterministic Decomposition of the Unsteady Flow in a Unidirectional Axial Turbine for OWC Plant
Authors: Alvarez Bertrand Nuria , Fernández Oro Jesús Manuel , Pereiras García Bruno , García Díaz Manuel 
Published: September 2018

The “twin-turbine” configuration has recently emerged as a feasible possibility for unidirectional turbines to be introduced in Oscillating Water Column wave energy plants without requiring auxiliary rectifying systems.
Previous investigations by the authors have been focused on the development of a numerical CFD model to analyze the performance of a unidirectional axial turbine for twin turbine configuration in an OWC system.
In this paper, all these numerical databases are further post-processed using a deterministic framework to give more insight about the flow patterns within the turbine. The final objective is the analysis of the unsteady features of the flow and the stator-rotor interactions using a deterministic decomposition. The present study reveals that levels of deterministic unsteadiness in the inter-row region are moderate, being more intense as the flow rate is decreased. Turbulence intensities are also observed to be clearly prominent in case of lower flow rates. Although these findings appear to be contradictory with the high-efficiency low flow rates of the turbine, the major levels of stator-rotor unsteadiness at higher flow rates (shown by the deterministic decomposition) justify the serious penalty in the aerodynamic efficiency as the turbine flow rate is increased. Finally, some advices with respect the design of the vane row in the turbine stage are given to control the generation of turbulence and stator-rotor interaction.
Technique for Early Consideration of Human Reliability (TECHR): Applying a Generic Model in an Oil Tanker Operation to Study Scenarios of Collision
Authors: Maturana Marcos Coelho , Martins Marcelo Ramos 
Published: September 2018

In the oil sector, analysis, evaluation, and management of risk are vital, considering the accidents potential severity with respect to human life, environment and property. Since the greater part of the accidents in this sector is caused by human factors, and given the lack of suitable tools for its consideration along the systems life cycle, especially in the design phase, the development of models and processes dedicated to human factors in risk analysis is essential.
In this context, a technique for early consideration of human reliability (TECHR) was designed for developing a prospective human performance model which can be exploited in the system design phase and which can be updated along the system life cycle. TECHR is based on the use of expert opinion in relation to systems that operate or have operated in recent years to obtain estimates of the probabilities of the various types of human error which may occur during the performance of a specific action.
This paper briefly presents the application of a prospective human performance model — obtained by the TECHR — in the study of an oil tanker operation, focusing the human factor quantification in scenarios of collision. In this work, the actions presented in a previous fault tree — for the vessel operation — are quantified considering the mentioned model, and the results are discussed in view of the previous results of this fault tree.
Flare Structure Heat-Up During Depressurization
Authors: Gasmi Rami , Cahay Marc 
Published: September 2018

Despite regulations becoming more and more stringent, significant quantities of gas are still flared around the world every year. Indeed, for safety reasons, flaring remains a usual practice in oil and gas production in cases of process upset. For instance, emergency shutdown, when the unit must be depressurized in a short period of time, most of the gas inventories are flared to limit as much as possible the potential consequences of fire and explosion within the facility.
With the increase of the global demand for energy and especially in Liquefied Natural Gas (LNG), the recent development of Floating Liquefied Natural Gas unit (FLNG) has raised new challenges concerning flare stack design. Since FLNG facilities handle large flammable gas quantities the flare stack needs to be designed considering much more stringent cases. It results in an increased length of flare stack, to reduce the radiation effects on personnel and equipment. The thermal response of the flare structure needs also to be accounted for in the design, in addition to other load cases such as piping and structural weight or vessel accelerations.
To accomplish the structural design of the flare stack, the engineers will have to convert the radiative heat fluxes from the flame into the resulting temperature of the structure exposed.
Indeed, temperature is the parameter that can be used as a thermal load case in any finite element analysis calculation code. Current temperature mapping methodologies applied on projects are not exhaustive and are often based on a simplified approach which is now challenged by operators and certification bodies who require more detailed verifications on flare structure heating during continuous or emergency flaring. Moreover, such simplified modelling approaches tends to overestimate thermal protection to mitigate the heat radiation impact.
The proposed approach described in this paper will address these points through a multidisciplinary workflow to form a flexible, simple and robust technical methodology to be applied during project execution. The proposed approach will assess heat radiation and temperature calculations in a spatial-temporal reference including the dynamic response.
This transient approach is more attractive as computed temperatures will be lower than steady-state approach results which are the usual engineering practice, especially for accidental loading cases, such as emergency depressurization, where the flare release can decrease quickly.
Calibration of a Time-Domain Numerical Hydrodynamic Model for Mooring Analysis of a Semi-Submersible
Authors: Fonseca Nuno , Stansberg Carl Trygve 
Published: September 2018

The paper presents calibration of a time domain numerical model for the motions of the Exwave Semi in high seastates with current. The time domain equations of motion combine linear radiation, linear diffraction and second order wave drift forces, based on MULDIF diffraction code, with nonlinear forces from quadratic damping and from the mooring system. Calibration is performed by comparing simulations with model test data and adjusting hydrodynamic coefficients known to be affected by uncertainty. These include wave drift force coefficients, damping and added mass coefficients. Correction of the drift coefficients is based on empirical quadratic transfer functions (QTFs) identified from the test data by a nonlinear data analysis technique known as “cross-bi-spectral analysis”.
Initial “uncalibrated” numerical models are based on input from the mooring, vessel mass, MULDIF hydrodynamic analysis, decay tests and current coefficients. They need adjustments for surge and sway. Empirical drift coefficients, natural periods and damping coefficients are then adjusted by matching low frequency surge and sway spectra. Wave-frequency coefficients need no adjustment. Low frequency wave drift forces, damping and added mass need increase in high sea states, in particular with current. Final motion simulations show 30%–40% underestimation in initial simulations, while final calibrated simulations are close to the measured records.
Applications of natural language processing (NLP) for improving classroom learning experiences using student surveys
Authors: Kuiper Patrick , Hood Karoline 
Published: September 2018

Academic institutions often assess the efficacy of courses by surveying students. These surveys are critical in structuring course content and evaluating instruction. Given the critical function of surveys for academic institutions, it is essential that surveys obtain data which is precise and accurate. Currently most institutions construct surveys employing the Likert scale: questions that require students to map their opinion on precise topics to a discrete, quantitative domain. These surveys uniformly weight response data, irrespective of student interest. We argue greater accuracy may be obtained by building Student-Directed Discussion Surveys (SDDSs) — surveys with several open-ended, student-directed questions, requiring free text responses. SDDSs retain precision by employing several Natural Language Processing (NLP) techniques including word frequency and sentiment analysis. We use SDDSs to improve course content and evaluate survey accuracy by comparing the results of an SDDS to a Likert-scaled survey administered to an overlapping population. We find that the results of these two survey techniques diverge when topics become increasingly significant to respondents. These results, in addition to the documented issues with Likert-scaled surveys, lead to the conclusion that SDDSs may provide more informative and insightful results.
Genomic Characterization of Six Virus-Associated Cancers Identifies Changes in the Tumor Immune Microenvironment and Altered Genetic Programs
Authors: Varn Frederick S. , Schaafsma Evelien , Wang Yue , Cheng Chao 
Published: September 2018

Abstract
Viruses affect approximately 20% of all human cancers and induce expression of immunogenic viral oncoproteins that make these tumors potent targets for immune checkpoint inhibitors. In this study, we apply computational tools to The Cancer Genome Atlas (TCGA) and other genomic datasets to define how virus infection shapes the tumor immune microenvironment and genetic architecture of 6 virus-associated tumor types. Across cancers, the cellular composition of the microenvironment varied by viral status, with virus-positive tumors often exhibiting increased infiltration of cytolytic cell types compared with their virus-negative counterparts. Analyses of the infiltrating T-cell receptor repertoire in these patients revealed that Epstein–Barr virus infection was associated with decreased receptor diversity in multiple cancers, suggesting an antigen-driven clonal T-cell response. Tissue-specific gene-expression signatures capturing virus-associated transcriptomic changes successfully predicted virus status in independent datasets and were associated with both immune- and proliferation-related features that were predictive of patient prognosis. Together, the analyses presented suggest viruses have distinct effects in different tumors, with implications for immunotherapy.
Significance: This study utilizes TCGA and other genomic datasets to further our understanding of how viruses affect the tumor immune response in different cancer types.
Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/22/6413/F1.large.jpg. Cancer Res; 78(22); 6413–23. ©2018 AACR.