bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase Behavior Modeling for Carbon Dioxide/Brine Mixtures Using PR EOS and Huron-Vidal Mixing Rule
Authors: Sun Ziting , Li Huazhou 
Published: October 2022

Abstract
Accurately predicting CO2 solubility in saline aquifers is very important for CO2 capture and storage. A reliable and accurate thermodynamic model is needed to predict the phase equilibrium of the CO2+brine systems over a wide range of temperature, pressure, and molality. In this study, a cubic-EOS-based thermodynamic model is presented to predict the phase equilibrium of CO2+brine mixtures. Peng-Robinson equation of state and Huron-Vidal mixing rule are applied to predict the phase behavior of CO2+brine systems containing salt species including NaCl, KCl, CaCl2, and MgCl2. Binary interaction parameters for specific CO2+single-salt+H2O systems are established as functions of temperature and salt molality. To investigate the impact of multiple salts mixtures on CO2 solubility in brine solutions, the model is extended to CO2+mixed-salt+H2O systems under the practical geological conditions (273–550K, 0–800 bar, 0–6 mol/kg). PR EOS with a modified BIP model in the HV mixing rule is implemented to capture the phase compositions in vapor-liquid equilibria (VLE). The collected experimental data are used to determine the optimal BIP model. Comparison of the experimental data and the computed data indicates that the average absolute deviation (AAD) in reproducing the CO2 concentration in the mixed-salt brine is 0.0015. Compared to other state-of-the-art models in the literature, the new model can more accurately predict the VLE of CO2+brine systems over a large temperature, pressure, and molality range.
Relevance of VPMM: A Survey, Conundrum and Conclusions
Authors: Miller Lakshmi Madhavan , Njaka Taylor , Brizzolara Stefano 
Published: October 2022

Abstract
This study concerns CFD-informed methods to obtain the derivatives of lumped parameters maneuvering models for underwater vehicles. The uncertainty in maneuvering predictions due to the method of obtaining hydrodynamic derivatives is discussed and assessed. Hydrodynamic derivatives are typically obtained from planar motion mechanism tests in both planes. Unsteady RANSE solvers offer the possibility to simulate the same captive steady and unsteady maneuvers to obtain these derivatives by identification procedures. Upon comparing some general representations of such identification procedures, it is found that the values of the estimated coefficient vary due to the method used. The uncertainty affecting the derivatives is propagated onto standard maneuvering predictions. This article discusses the level of uncertainty related to each method and offers insight based on the type of derivatives that vary as well as the type of maneuvers that are affected through the application on two different underwater vehicles. It is observed that there is a recognizable difference in the accuracy and applicability of these methods and a possible way forward is proposed.
Numerical Investigation of Ship Anchor Penetration in Cohesive Baltic Sea Soil
Authors: Dao Duy A. , Grabe Jürgen 
Published: October 2022

Abstract
One of the main reasons for damage to embedded offshore infrastructure is anchor penetration. Sea cables, for example, are harmed either by direct anchor contact or by additional pressure caused by anchor dragging above the cable. A sufficient permanent burial depth is required to minimize the risk of failure due to anchor penetration. This work presents the numerical simulation of the penetration process of two ship anchors (HHP AC-14 and Spek) in cohesive soil of the Baltic Sea. The simulations are carried out using the Coupled Euler-Lagrange (CEL) method in Abaqus/Explicit. Baltic Sea silt, under undrained conditions, is modeled. For the creep, relaxation behavior, and velocity dependence of the soil, the visco-hypoplastic constitutive model, according to [1], is used. Soil parameters have been obtained by laboratory tests. A parametric study is conducted varying anchor type, mass, and velocity, which significantly influence penetration depth and penetration behavior.
Big Data Analytics for Assistance Operation Identification in Ice-Covered Waters
Authors: Liu Cong , Musharraf Mashrura , Kujala Pentti , Toivola Jarkko 
Published: October 2022

Abstract
In winter, shipping activities in the Baltic Sea area involve risks because of the harsh navigational environment. To ensure maritime safety and the efficiency of the transport system, icebreaker assistance is needed when the ship is not able to navigate independently in the prevailing ice condition. The existing ship operation mode determination practices are primarily based on empirical knowledge. To better understand when the assistance operation is needed for various ships operating in real ice conditions from a quantitative perspective, this paper proposes the use of a data-driven assistance operation identification model. The model combines different data types, including Automatic Identification System (AIS) data and ice data that portray the real operational conditions in the Baltic Sea. The aim is to measure temporal-spatial similarities among trajectories of icebreakers and potentially assisted ship(s) using clustering algorithms, automatically identifying assistance scenarios in ice-covered waters. Both the static voyage features (e.g., ship types, departures /destinations, voyage length) and the dynamic navigation features (e.g., speed, course, and ship trajectory spatial distance) are considered in the model. The outcomes of the model would assist in better understanding of ship behaviors and coupled kinematics of ships linking with the following distance and speed under icebreaker assistance in various ice conditions. They would also contribute to data-driven ship operation mode determination, therefore supporting the development of an intelligent decision support system in winter navigation.
Control Co-Design of a Hydrokinetic Turbine With Open-Loop Optimal Control
Authors: Jiang Boxi , Amini Mohammad Reza , Liao Yingqian , Martins Joaquim R. R. A. , Sun Jing 
Published: October 2022

Abstract
This paper introduces a control co-design (CCD) framework to simultaneously explore the physical parameters and control spaces for a hydro-kinetic turbine (HKT) rotor optimization. The optimization formulation incorporates a coupled dynamic-hydrodynamic model to maximize the rotor power efficiency for various time-variant flow profiles. The open-loop optimal control is applied for maximum power tracking, and the blade element momentum theory (BEMT) is used to model the hydrodynamics. Case studies with different control constraints are investigated for CCD. Sensitivity analyses were conducted with respect to different flow profiles and initial geometries. Comparisons are made between CCD and the sequential process, with physical design followed by a control design process under the same conditions. The results demonstrate the benefits of CCD and reveal that, with control constraints, CCD leads to increased energy production compared to the design obtained from the sequential design process.
Prediction of Inclined Surface Spreading Extent for High Flashpoint Fuel in Large Compartments Under Ship Motion
Authors: Baeg Dae Yu , Lee Hyun Ho , Lee Seung Yul , Kim Seon Jin , Kim Jeong Hwan , Seo Jung Kwan 
Published: October 2022

Abstract
Fire accidents can occur on in-service ships and offshore installations due to the spillage of fuels from components such as storage tanks and valves under accidental and extreme conditions. In such accidents, the liquefied fuel spread area on the decks are affected by ship motion and properties of the fuel, which may cause a pool fire to develop into a large-scale fire, resulting in casualties and severe damage to property and the environment. Therefore, the effects of surface spread extent on the structural response of ships and offshore installations should be examined. Additional safety measures are particularly necessary on ships with large compartments, such as Ro-Ro ships. However, these fire hazards and their preventive measures have not been sufficiently explored. Thus, in this study, fuel discharge experiments were conducted to investigate the fuel spreading behavior at different substrate slopes and discharge rates. Based on the results, empirical formulae that predict the spreading extent of liquefied fuel in large compartments were derived. Additionally, the proposed formulae were used to investigate the variation of heat release rate in different spillage scenarios.
Advanced Laboratory Setup to Determine and Verify Cement Sheath Integrity
Authors: Taghipour Ali , Feneuil Blandine , Vrålstad Torbjørn , Skorpa Ragnhild 
Published: October 2022

Abstract
It is crucial to ensure that stored CO2 does not leak into the atmosphere. As the last step in the Carbon Capture and Storage (CCS) process, CO2 is injected into underground formations, and it should remain stored there for eternity. However, when reusing old petroleum wells for CO2 storage, defects in the cement sheath, such as microannuli or radial cracks, might be present from production operations such as shut down/startups or from the injection process itself. Thus, causing a possible leak path for CO2 through the cement. Upon reaction with CO2 the cement carbonates, and this carbonation process may in fact seal the cracks in the cement. This so-called self-healing effect has been studied experimentally for many years, but, to the best of our knowledge, none of these studies were performed with realistic well geometries with cracked cement sheaths.
An advanced experimental setup has been developed to study the sealing process of realistic cracks in the cement sheath by flowing CO2 through radial cracks and investigate the effect of flow rate and exposure time for different cement systems. The setup consists of a modular based downscaled section of a wellbore with rock, cement, and casing, and allows for a confining pressure up to 100 bar around the rock. Pressure cycling experiments are performed on the cement sheath by increasing the pressure from inside the casing, causing realistic radial cracks in the cement sheath. When these cracks are connected axially through the sample, they provide a leak path for fluids through the cement. This novel setup allows for a direct exposure of the bottom of a microannuli or radial crack with CO2, and thus measure the flow through the cracks and study the possible healing effects by CO2. The novelty of the setup lies in a movable support of the cement sheath. The first position allows a firm support for the cement upon curing, and the second, at a lower level opens the ports for CO2 exposure and exposes the full bottom surface of the cement sheath. The cracks in the cement sheath were visualized using μ-CT both prior to and after CO2 experiments.
The paper describes in detail the novel laboratory setup and the applicability of the setup.
Flowability of Dry and Water Wet Barite Powder
Authors: Skorpa Ragnhild , Feneuil Blandine , von Hafenbrädl Franz Otto , Ratnayake Chandana 
Published: October 2022

Abstract
Barite is added to drilling fluids as weight material to increase its density. Over time, when the drilling fluids are left static in the annulus, gravitational forces will make the barite settle out. This settled barite is today the main reason for casing cut and removal process, which accounts for up to 50% of time related to P&A operations. Knowledge of settled barite on top of cement behind casing is also essential for perf, wash & cement procedures.
The most compact barite sediment can be characterized as a non-elastic dense wet particle sediment where the packing of the particles and the particle size of the grains varies. To fully understand the packing mechanism of the consolidated barite sediments characterization of barite powder (both dry and wet) is important.
In this study we have done comparable measurements with a Jenike shear test, which measures direct shear strength under different loading conditions, and compared these to rheological measurements using an Anton Paar powder module under the same loading conditions. Experiments were performed on both dry and wet (by 2.5 wt% and 5 wt% water) barite and with 1, 3, 6 and 9 kPa loading.
The results from the Jenike test and the powder module were found to be complimentary. At a low water content, the sample showed an increase in flowability, while with a high-water content a decrease the flowability was observed compared to that of dry barite.
Practical Application of Pressure and Temperature Dependent Viscosity Calculations in Well Cementing Simulations
Authors: Flamant Nicolas C. , Pelipenko Sviatoslav 
Published: October 2022

Abstract
During well cementing and drilling operations, proper control of downhole pressure is critical for controlling the well, i.e. avoiding formation fluids influx or fracturing the formation, and hence ensuring successful well construction operations. At the planning stage, well control is investigated using numerical hydraulics simulations. During actual operations, annular pressure-while-drilling (APWD) is often, but not systematically, available while drilling but not while cementing. Here again well control relies on simulations. Accurate prediction of downhole pressures is therefore a key requirement for well control, whether at the planning stage or in real-time during operations.
Fluid properties are a key input to the hydraulics simulations, in particular fluid viscosity, which is required to estimate friction pressure losses. A difficulty is the dependence of viscosity on pressure and temperature. At a given shear rate, the viscosity of drilling and cementing fluids continuously changes within the flow path, and variations of several tens of percent are common. Hence it is paramount to measure cementing and drilling fluids viscosity over the pressure and temperature domain that will be experienced in the well, but also to fit to the measurements a pressure and temperature dependent rheological model that will allow the hydraulics simulator to obtain viscosity at any shear rate, temperature, and pressure values.
We first provide an overview of the algorithms needed to analyze rheological lab measurements, where care must be taken to account for potential wall slip effects. We then review how to account for pressure and temperature effects, via the use of Arrhenius and Barus laws, and why the modeling needs should inform the test requirements.
Digital Twin Based Structural Health Monitoring of Offshore Crane
Authors: Rølvåg Terje , Stranden Øystein 
Published: October 2022

Abstract
This paper presents a novel approach for implementation of digital twin (DT) based Structural Health Monitoring (SHM) of an Palfinger offshore knuckle boom crane. Contrary to most harbor gantry cranes, knuckle boom cranes are highly nonlinear mechanisms that cannot be represented by static reduced order twin models. Such cranes need to be solved by non-linear finite element solvers. The digital twin representation of the Palfinger crane is modelled and simulated real-time in a nonlinear finite element (FE) program, driven by inputs from physical sensors. Model reduction techniques are applied to enable DT co-simulation running two times faster than the physical crane. The inputs from the standard crane instrumentation are processed for noise reduction and singularity removal and converted to hydraulic actuator inputs. A simple inverse method for estimation of the crane payload is implemented based on hydraulic pressures. Structural loads due to wave induced ship motions are predicted based on sensor signals from the ship IMU. Based on the standard ship and crane instrumentation, the digital twin allows for real-time determination of stresses, strains and loads at an unlimited number of hot spots. Hence, a digital twin can be an effective tool for predictive maintenance of real offshore knuckle boom cranes with minor additional costs. The presented approach is described in a general manner and is applicable for offshore cranes used in the industry.
Optimization of Semi-Submersible Hull Design for Floating Offshore Wind Turbines
Authors: Hsu I-Jen , Ivanov Glib , Ma Kai-Tung , Huang Zheng-Zhang , Wu Hua-Tung , Huang Yun-Tzu , Chou Mike 
Published: October 2022

Abstract
As wind energy developers start venturing into deeper waters with depths greater than 65 meters, the floating offshore wind turbines (FOWTs) are becoming the preferred solutions there over bottom-fixed structures. This paper summarizes the design of a semi-submersible platform for hosting a 15MW turbine. While semi-submersible origins from the oil & gas industry, the FOWT presents a different set of requisites and conditions for designing it. Recent existing and planned projects can be characterized by excessive use of steel and dimensions, compared to bottom-fixed structures. This paper aims to optimize the hull structure of a semi-submersible platform to be as cost-effective as possible while fulfilling the following design considerations: strength, vessel stability in still water and dynamic conditions, constructability, and operability. Meanwhile, the design is made to satisfy the rule requirements of major classification societies. Through a literature survey, data on existing semi-submersible projects is gathered and analyzed. The ratios of vessel displacement to hull steel weight relations are presented to show the trend. A high-level overview of class rules is given. An example platform, TaidaFloat, designed to carry a 15MW turbine is introduced. Its application is targeting a water depth from 65 to 100 meters with a deployment in Taiwan Strait in mind. The platform is designed against some limits and constraints, e.g. ensuring that it meets stability criteria. Its internal structural arrangement is preliminarily developed, and the steel weight is compared to recent projects. Features of the design are introduced, and their advantages are summarized.
Post-acute sequelae of covid-19 six to 12 months after infection: population based study
Authors: Peter Raphael S , Nieters Alexandra , Kräusslich Hans-Georg , Brockmann Stefan O , Göpel Siri , Kindle Gerhard , Merle Uta , Steinacker Jürgen M , Rothenbacher Dietrich , Kern Winfried V 
Published: October 2022

Abstract

Objectives
To describe symptoms and symptom clusters of post-covid syndrome six to 12 months after acute infection, describe risk factors, and examine the association of symptom clusters with general health and working capacity.

Design
Population based, cross sectional study

Setting
Adults aged 18-65 years with confirmed SARS-CoV-2 infection between October 2020 and March 2021 notified to health authorities in four geographically defined regions in southern Germany.

Participants
50 457 patients were invited to participate in the study, of whom 12 053 (24%) responded and 11 710 (58.8% (n=6881) female; mean age 44.1 years; 3.6% (412/11 602) previously admitted with covid-19; mean follow-up time 8.5 months) could be included in the analyses.

Main outcome measures
Symptom frequencies (six to 12 months after versus before acute infection), symptom severity and clustering, risk factors, and associations with general health recovery and working capacity.

Results
The symptom clusters fatigue (37.2% (4213/11 312), 95% confidence interval 36.4% to 38.1%) and neurocognitive impairment (31.3% (3561/11 361), 30.5% to 32.2%) contributed most to reduced health recovery and working capacity, but chest symptoms, anxiety/depression, headache/dizziness, and pain syndromes were also prevalent and relevant for working capacity, with some differences according to sex and age. Considering new symptoms with at least moderate impairment of daily life and ≤80% recovered general health or working capacity, the overall estimate for post-covid syndrome was 28.5% (3289/11 536, 27.7% to 29.3%) among participants or at least 6.5% (3289/50 457) in the infected adult population (assuming that all non-responders had completely recovered). The true value is likely to be between these estimates.

Conclusions
Despite the limitation of a low response rate and possible selection and recall biases, this study suggests a considerable burden of self-reported post-acute symptom clusters and possible sequelae, notably fatigue and neurocognitive impairment, six to 12 months after acute SARS-CoV-2 infection, even among young and middle aged adults after mild infection, with a substantial impact on general health and working capacity.

Trial registration
German registry of clinical studies DRKS 00027012.
Scoping and targeted reviews to support development of SPIRIT and CONSORT extensions for randomised controlled trials with surrogate primary endpoints: protocol
Authors: Manyara Anthony Muchai , Davies Philippa , Stewart Derek , Wells Valerie , Weir Christopher , Young Amber , Taylor Rod , Ciani Oriana 
Published: October 2022

IntroductionUsing a surrogate endpoint as a substitute for a primary patient-relevant outcome enables randomised controlled trials (RCTs) to be conducted more efficiently, that is, with shorter time, smaller sample size and lower cost. However, there is currently no consensus-driven guideline for the reporting of RCTs using a surrogate endpoint as a primary outcome; therefore, we seek to develop SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) and CONSORT (Consolidated Standards of Reporting Trials) extensions to improve the design and reporting of these trials. As an initial step, scoping and targeted reviews will identify potential items for inclusion in the extensions and participants to contribute to a Delphi consensus process.Methods and analysisThe scoping review will search and include literature reporting on the current understanding, limitations and guidance on using surrogate endpoints in trials. Relevant literature will be identified through: (1) bibliographic databases; (2) grey literature; (3) handsearching of reference lists and (4) solicitation from experts. Data from eligible records will be thematically analysed into potential items for inclusion in extensions. The targeted review will search for RCT reports and protocols published from 2017 to 2021 in six high impact general medical journals. Trial corresponding author contacts will be listed as potential participants for the Delphi exercise.Ethics and disseminationEthical approval is not required. The reviews will support the development of SPIRIT and CONSORT extensions for reporting surrogate primary endpoints (surrogate endpoint as the primary outcome). The findings will be published in open-access publications.This review has been prospectively registered in the OSF Registration DOI: 10.17605/OSF.IO/WP3QH.