bluuebunny/crossref_metadata_2025 huggingface dataset:
Transmission reconstruction of transparent solutions using particle swarm optimisation
Authors: Farazandemehr Elham , Daneshvar Elaheh
Published: October 2021

In this paper, we present a new approach for transmission reconstruction of transparent solutions by combining the particle swarm optimisation algorithm and the matrix S method. To perform colorimetric characterisation, a digital camera was characterised using a training set of coloured solutions and the particle swarm optimisation method to obtain an optimised transfer matrix of RGB to CIE XYZ values. Then the transformation matrix was used to calculate the CIE XYZ values of test colour solutions. Next, the estimated CIE XYZ values were used to reconstruct the transmission spectra of the unknown solutions by applying the matrix S method. The experimental results on real datasets demonstrate that the proposed technique significantly outperforms the existing method in terms of transmission reconstruction.
Association of race and gender with primary caregiver relationships and eligibility for advanced heart failure therapies
Authors: Steinberg Rebecca S. , Nayak Aditi , Burke Michael A. , Aldridge Morgan , Raja Laskar S. , Bhatt Kunal , Sridharan Lakshmi , Abdou Mahmoud , Attia Tamer , Smith Andrew , Daneshmand Mani , David Vega J. , Gupta Divya , Morris Alanna A.
Published: October 2021

Background

Caregiver support is considered necessary after heart transplant (HT) and left ventricular assist device (LVAD) for patients with end‐stage heart failure (HF). Few studies have demonstrated how caregivers differ by gender and race, and whether that impacts therapy eligibility.

Methods

We examined caregiver relationships among 674 patients (32% women, 55% Black) evaluated at Emory University from 2011 to 2017. Therapy readiness was assessed using the Stanford Integrated Assessment for Transplant (SIPAT). Evaluation outcome according to caregiver relationship was compared using χ2 analysis. Multivariable logistic regression determined the association between caregiver and eligibility according to gender and race.

Results

Women and Black patients were less likely to have spouses as their support person (P < .001). Women were less likely to be considered eligible for advanced therapies (adjusted odds ratio [aOR] .64, 95% confidence interval [CI] .46–.89; P = .008), with Black women having lower eligibility than White women (aOR .28, 95% CI .11–.72; P = .008). Social support and SIPAT scores did not significantly influence eligibility by gender or race.

Conclusion

Lack of caregiver support is considered a relative contraindication to advanced therapies. Type of caregiver in our cohort varied according to race and gender but did not explain differences in eligibility for advanced therapies.
Sarcopenia in high acuity liver transplantation: Does it predict outcomes?
Authors: Ito Takahiro , Guorgui Jacob , Markovic Daniela , Coy Heidi , Younan Stephanie M. , DiNorcia Joseph , Agopian Vatche G. , Farmer Douglas G. , Raman Steven S. , Busuttil Ronald W. , Kaldas Fady M.
Published: October 2021

Background

Sarcopenia has gained momentum as a potential risk‐stratification tool in liver transplantation (LT). While LT recipients recently have more advanced end‐stage liver disease, the impact of sarcopenia in high acuity recipients with a high model for end‐stage liver disease (MELD) score remains unclear.

Methods

We retrospectively assessed sarcopenia by calculating skeletal muscle index (SMI) from cross‐sectional area at third lumbar vertebra (cm2) and height (m2) in 296 patients with a CT ≤ 30 days prior to LT. Sex‐specific SMI cut‐offs were developed, and its impact was assessed in patients with MELD ≥ 35.

Results

In patients with MELD ≥ 35 (n = 217), men with a SMI < 30 cm2/m2 had significantly higher rates of bacteremia (P = .021) and a longer hospital stay (P < .001). Women with a SMI < 34 cm2/m2 had a longer hospital stay (P = .032). There were no relationships between SMI and survival in men and women with MELD ≥ 35.

Conclusions

This series examined sarcopenia with a focus on high MELD patients. Although decreased SMI contributed to higher post‐LT hospital stay, it did not impact patient survival, suggesting that while SMI alone may not aid in patient selection for LT, it certainly may guide perioperative care‐planning in this challenging patient population.
Antidepressant use and stroke or mortality risk in the elderly
Authors: Ön Begüm Irmak , Vidal Xavier , Berger Ursula , Sabaté Mònica , Ballarín Elena , Maisterra Olga , San‐Jose Antonio , Ibáñez Luisa
Published: October 2021

Background and purpose

Current evidence on antidepressant‐related stroke or mortality risk is inconsistent. Because the elderly have the highest exposure to antidepressants, the aim was to quantify their association with stroke and mortality risks in this vulnerable population.

Methods

Persons over 65 years old and registered in the Information System for Research in Primary Care of Catalonia during 2010–2015 comprised the study population. Antidepressant exposure was categorized into current‐users, recent‐users, past‐users and antidepressant non‐users (controls). The effect of antidepressant exposure on stroke or death, whichever came first, was analyzed by Cox regression adjusted for established risk factors.

Results

Of the 1,068,117 participants included, 20% had antidepressant reimbursements during follow‐up, 17% had a stroke and 3% died. The risk of experiencing stroke or death was higher in antidepressant current‐users (hazard ratio [HR] 1.04; 95% confidence interval [CI] 1.02–1.06), recent‐users (HR 3.34; 95% CI 3.27–3.41) and past‐users (HR 2.06; 95% CI 2.02–2.10) compared to antidepressant non‐users. Antidepressant current‐use was associated with increased stroke (HR 1.56; 95% CI 1.50–1.61) but decreased mortality risk (HR 0.93; 95% CI 0.91–0.94). During antidepressant recent‐use and past‐use, both stroke and mortality risks were significantly increased compared to no antidepressant use.

Conclusions

Antidepressant use may be associated with increased stroke risk in the elderly. When using antidepressants in this population, the potential risks should be considered.
Sexual dysfunction in a cohort of patients with moderate‐to‐severe atopic dermatitis. Influence of dupilumab treatment
Authors: Linares‐Gonzalez Laura , Lozano‐Lozano Ignacio , Gutierrez‐Rojas Luis , Ruiz‐Villaverde Ricardo , Lozano‐Lozano Mario
Published: October 2021

Introduction

Atopic dermatitis is a systemic and immune‐mediated dermatological disease that comprises a wide group of physiological and psychological comorbidities. Within the latter, the evaluation of anxiety and depression has been the subject of numerous studies, but sexual dysfunction (SD) is a fact that is rarely addressed in the literature. The objective of the present study is to assess the prevalence of SD in a cohort of patients with moderate‐to‐severe atopic dermatitis (AD) and to establish the possible impact of dupilumab therapy on it.

Material and methods

A cross‐sectional study was performed. Recruited patients had been diagnosed with moderate‐to‐severe AD at the Dermatology Unit of the Hospital Universitario San Cecilio, Granada, Spain, from July 1, 2019, through June 30, 2020. They were followed up for a 6‐month period during which the impact of dupilumab treatment was measured. The main variable under study, sexual dysfunction, was evaluated differently according to gender. Regarding the male patients, the International Index Erectile Function (IIEF‐5) was applied, whereas for female patients, the questionnaire “Female Sexual Function Index” was used.

Results

Our study included 31 patients, 18 men and 13 women. Men’s mean age was 35 +/− 14.55 years, while that of women was 33 +/− 10.46 years. Seventy‐nine percent of patients in our series (n = 22) had SD compared to 29% (n = 9) who did not. A total of 66.9% of males and 76.9% (n = 10) of females sampled, suffered from SD. Six months after initiation of treatment, none of the patient had stopped it due to efficacy or safety issues. All severity indices (SCORAD, EASI, VAS pruritus, and DLQI) had significantly improved by more than 50% from baseline. The improvement in the sexual dysfunction index had improved by four points, both in the male and female patients.

Discussion

Many large population studies on SD in patients with moderate‐to‐severe atopic AD only focus on male gender and clinical diagnoses, rather than specific and validated questionnaires. Dupilumab treatment in patients with moderate‐to‐severe AD has shown a positive impact on the levels of SD in both male and female populations. Further studies focused on populations with mild atopic AD and with larger sample sizes are required to corroborate these preliminary results.
Enhancing glass anode performance for lithium‐ion batteries via crystallization
Authors: Qi Shibin , Li Xiangyu , Jiang Zhenjing , Zhang Jiayan , Shan Zhitao , Zhang Yanfei
Published: October 2021

We investigate the thermal and electrochemical properties of xFe2O3‐(100‐x) P2O5 glass (x = 20, 30, 40, and 50 mol%) and 50Fe2O3‐50P2O5 (50FeP) glass‐ceramics as anodes for lithium‐ion batteries (LiBs). The results show that both the glass transition temperature and the energy bandgap monotonically decrease with the increasing Fe2O3 while a critical Fe2O3 content of 30 mol% is found to give glass the highest thermal stability, the largest capacity at 1 Ag‐1, and the lowest charge‐transfer resistance before cycling. Moreover, Fe3(P2O7)2 crystals formed during heat treatment in 50FeP glass effectively enhances the electrochemical properties. The optimum heat treatment condition for 50FeP glass is found at 1033 K for 4 h, that is, 1033 K‐4 h sample enables a reversible capacity of 237 mA h g−1 at the end of 1000 cycles at 1 Ag‐1, which is more than 1.5 times higher than that of the 50FeP glass‐based anode. These findings suggest that the Fe2O3‐P2O5 glass‐ceramics hold significant potential for the effective development of new types of glass anodes for future advanced LiBs.
Indentation deformation and cracking behavior of hydrated aluminoborate glasses
Authors: Liu Pengfei , Jensen Lars R. , Gao Chengwei , Smedskjaer Morten M.
Published: October 2021

Aluminoborate glasses have recently been found to feature high resistance to crack initiation during indentation due to a highly flexible network structure. In cesium aluminoborate glasses, it has been found that the use of a simple post‐treatment, namely aging in a humid atmosphere, can further improve this resistance. To better understand the mechanical properties of this glass family upon humid aging, we here study the effect of aging conditions on the structure and mechanical properties of Li,K,Cs‐aluminoborate glasses. As expected, we find that higher humidity and longer aging time cause more pronounced permeation of atmospheric water into the glasses. Due to their denser structure and stronger modifier‐oxygen bonds, the humid aging has a relatively smaller effect on the mechanical properties of Li‐ and K‐containing glasses relative to Cs‐containing glasses, with the latter achieving an ultrahigh crack resistance. We find that the humid aging leads to the formation of a hydration layer in the Cs‐aluminoborate glass surface, with a thickness of around 26 μm upon aging at 23 °C with 40% relative humidity for 7 days. Moreover, a remarkable indentation behavior, that is, the observation of μm‐sized shear bands inside the imprint of the Cs‐glass upon aging at 60% relative humidity is reported. Taken as a whole, the work provides guidelines for how to control the humid aging rate as a function of relative humidity and temperature to form a hydration layer and thus achieve improved crack resistance in such glasses.
Leveraging resources for innovation: The role of synchronization
Authors: Carnes Christina Matz , Hitt Michael A. , Sirmon David G. , Chirico Francesco , Huh Dong Wook
Published: October 2021

Leveraging resources to develop innovation is central to exploiting market opportunities, yet doing so is complex and fraught with challenges. This study explores some of this complexity by theoretically detailing and empirically examining the critical role that synchronization plays in the process of leveraging resources to create innovation. Specifically, we integrate resource orchestration with the behavioral theory of the firm to investigate the joint effect of synchronization and leveraging strategies on innovation under different performance conditions. Using policy capturing methodology resulting in 3600 observations from 120 managers, we find empirical evidence that synchronization can enhance innovation outcomes of all leveraging strategies. Yet, this positive synergistic effect occurs in high performing firms that use the resource advantage and market opportunity leveraging strategies and in low performing firms that use the entrepreneurial leveraging strategy. Our theory and results offer important contributions to the innovation and resource orchestration literatures. First, our study offers a contextually rich examination of innovation, suggesting that it is not only resources, but also managerial actions and a firm's relative performance that drive innovation outcomes. Specifically, this study adds to our knowledge of the relationship between resources and innovation strategies by investigating the impact of synchronization—a key contingency in understanding the effects of resources on innovation. Second, we examine boundary conditions of synchronization's influence by integrating behavioral logic in the context of relative firm performance. Mixed evidence exists on the synergistic effect of valuable capabilities, with some studies showing increased gains and others finding evidence of a neutral relationship. This study begins to disentangle these findings by suggesting that resource leveraging strategies and synchronization together enhance innovation when the strategy aligns with the firm's relative performance aspirations, answering calls for the development of a more nuanced understanding of the pursuit of innovation.
Daily Mortality/Morbidity and Air Quality: Using Multivariate Time Series with Seasonally Varying Covariances
Authors: Huang Guowen , Brown Patrick E. , Fu Sze Hang , Shin Hwashin Hyun
Published: October 2021

We study the associations between daily mortality and short-term variations in the ambient concentrations of fine particulate matter (PM2.5), nitrogen dioxide (NO2) and ozone (O3) in four cities in Canada. First, a novel multivariate time series model within Bayesian framework is proposed for exposure assessment, where the response is a mixture of Gamma and Half-Cauchy distributions and the correlations between pollutants vary seasonally. A case-crossover design and conditional logistic regression model is used to relate exposure to disease data for each city, which then are combined to obtain a global estimate of exposure health effects allowing exposure uncertainty. The results suggest that every 10 ppb increase in O3 is associated with a 3.88% (95% credible interval [CI], 2.5%, 5.18%) increase in all-cause mortality, a 5.04% (2.84%, 7.43%) increase in circulatory mortality, a 7.87% (2.4%, 12.9%) increase in respiratory mortality, a 0.76% (0.19%, 1.35%) increase in all-cause morbidity and a 6.6% (0.58%, 12.7%) increase in respiratory morbidity. Similarly, every 10 ppb increase in NO2 is associated with a 2.13% (0.42%, 3.87%) increase in circulatory morbidity. The health impacts of PM2.5 are not found to be present once other pollutants are accounted for.
Predicting nonsuicidal self‐injury using a variant of the implicit association test
Authors: Cathelyn Femke , Van Dessel Pieter , De Houwer Jan
Published: October 2021

Objective

Nonsuicidal self‐injury (NSSI) is a severe problem, and its prevalence is increasing. To aid prevention and treatment, there is an urgent need for evidence‐based measures to identify individuals at risk for NSSI. Measures that probe past NSSI are most promising, but people are often motivated to conceal NSSI behavior. This problem can be overcome by using implicit measures, which do not require individuals to self‐report on their behavior. Yet, prior research typically found weak predictive utility of implicit measures. Based on a new perspective on implicit measures and recent findings in NSSI research, we developed an Implicit Association Test that probes past NSSI (the P‐NSSI‐IAT).

Method

We report two preregistered studies (N = 83; N = 372) in which we tested the utility of the P‐NSSI‐IAT to detect past NSSI and predict NSSI one month later.

Results

P‐NSSI‐IAT scores (a) differentiated injury groups from non‐injury groups and (b) prospectively predicted NSSI and improved prediction above and beyond risk factors of NSSI.

Conclusions

These initial findings suggest that the P‐NSSI‐IAT is a promising tool for NSSI risk assessment. Future studies should further examine the predictive utility of this newly developed measure for NSSI behavior.
The genetic association with injury risk in male academy soccer players depends on maturity status
Authors: Hall Elliott C. R. , Baumert Philipp , Larruskain Jon , Gil Susana M. , Lekue Josean A. , Rienzi Edgardo , Moreno Sacha , Tannure Marcio , Murtagh Conall F. , Ade Jack D. , Squires Paul , Orme Patrick , Anderson Liam , Brownlee Thomas E. , Whitworth‐Turner Craig M. , Morton James P. , Drust Barry , Williams Alun G. , Erskine Robert M.
Published: October 2021

It is currently unknown if injury risk is associated with genetic variation in academy soccer players (ASP). We investigated whether nine candidate single nucleotide polymorphisms were associated (individually and in combination) with injury in ASP at different stages of maturation. Saliva samples and one season's injury records were collected from 402 Caucasian male ASP from England, Spain, Uruguay, and Brazil, whose maturity status was defined as pre‐ or post‐peak height velocity (PHV). Pre‐PHVCOL5A1rs12722 CC homozygotes had relatively higher prevalence of any musculoskeletal soft tissue (22.4% vs. 3.0%,p = 0.018) and ligament (18.8% vs. 11.8%,p = 0.029) injury than T‐allele carriers, whileVEGFArs2010963 CC homozygotes had greater risk of ligament/tendon injury than G‐allele carriers. Post‐PHVIL6rs1800795 CC homozygotes had a relatively higher prevalence of any (67.6% vs. 40.6%,p = 0.003) and muscle (38.2% vs. 19.2%,p = 0.013) injuries than G‐allele carriers. Relatively more post‐PHVEMILIN1rs2289360 CC homozygotes suffered any injury than CT and TT genotypes (56.4% vs. 40.3% and 32.8%,p = 0.007), while the “protective”EMILIN1 TT genotype was more frequent in post‐ than pre‐PHV ASP (22.3 vs. 10.0%,p = 0.008). Regardless of maturity status, T‐alleles ofACTN3rs1815739 andEMILIN1rs2289360 were associated with greater absence following ankle injury, while theMMP3rs679620 T‐allele andMYLKrs28497577 GT genotype were associated with greater absence following knee injury. The combination of injury‐associated genotypes was greater in injured vs. non‐injured ASP. This study is the first to demonstrate that a genetic association exists with injury prevalence in ASP, which differs according to maturity status.
Violación al patrimonio cultural en Teotihuacán y Cuernavaca, México
Authors: Lay Arellano Tonatiuh
Published: October 2021

En este artículo se hace una revisión de los casos de San Juan Teotihuacán, en el Estado de México, y de Cuernavaca, en el Estado de Morelos, en México, en donde las tiendas Walmart y Costco se instalaron en predios con existencia de vestigios arqueológicos e históricos, respectivamente, afectando el patrimonio cultural del lugar. Esta situación provocó diversas manifestaciones y movilizaciones, las cuales finalmente fueron desestimadas no por la razón jurídica, sino por acciones de colusión entre las autoridades gubernamentales y las empresas en cuestión.

Este texto tiene el objetivo realizar un recuento de los argumentos y posturas dadas a conocer, sobre todo por la prensa, con lo cual se pretende compilar los testimonios de los actores, como fuente de memoria de hechos no sólo ilegales, sino que presumiblemente afectaron el patrimonio cultural de diversas comunidades.
Parametric Numerical Study on the Self-Propulsive Performance of The DARPA Suboff Submarine via the Body-Force Propeller Method
Authors: Takahashi Kenshiro , Mori Takayuki
Published: October 2021

This study is based on previous works in a series of numerical studies on submarine hydrodynamics, which involved developing a computational fluid dynamics method to estimate the self-propulsive performance of underwater vehicles. Herein, the Defense Advanced Research Projects Agency SUBOFF submarine model was adopted as a benchmark. The computational modeling applied was based on the Reynolds-averaged Navier-Stokes turbulence model. A body-force propeller method was adopted to model the propulsion. The self-propulsive performance was verified via mesh refinement and validated by comparing the computational solutions with the results obtained from the experiments. The effect of the Reynolds number on the self-propulsive performance was investigated by varying the positions of the stern planes, while the free surface effect was determined by varying the Froude number (Fr) via the volume of fluid method. The computed Taylor wake fraction (w) and hull efficiency (ηH) depended on the Reynolds number as it decreased monotonically. The w and thrust deduction fraction (t) for the model of aft-fitted stern planes were approximately 3–7% and 8–10% higher than those of the baseline and fore-fitted stern planes, respectively. The differences in ηH between the models were insignificant. Regarding the free surface effects, the computations of w, t, and ηH generally decreased with Fr, thus exhibiting several humps and hollows. The computed upward suction force and pitching moment varied from negative to positive and vice versa, depending on Fr.
Automated Pattern Recognition in Real-Time Drilling Data for Early Karst Detection
Authors: Maksimov Danil , Løken Marius Alexander , Pavlov Alexey , Sangesland Sigbjørn
Published: October 2021

Drilling in carbonate formations often poses a real challenge to operators, contractors and service companies. Severe fluid losses, gas kicks and other unwanted situations increase drilling risks. These risks are closely related to drilling through karsts — vugs, cavities and fractures. Therefore it is important to detect karsts early enough to avoid drilling into them or, once drilling in a karstification region is detected, to prepare risk mitigating actions. Some geophysical methods can be used for karsts detection, however, they have limitations and cannot guarantee early detection of karsts. One of the recent studies has shown that certain patterns in real-time drilling data can serve as indicators of zones with a higher likelihood of encountering karsts. In this paper, we demonstrate how these patterns can be detected in an automated manner with an adaptive differential filter algorithm. The method has been validated on real drilling data.
Opportunities With Renewable Wave Energy and Challenges in the Design of Floating Wave Energy Converter Systems
Authors: Ringsberg Jonas W. , Yang Shun-Han
Published: October 2021

Wave energy is one among several resources of renewable energy which needs to be utilized in the future to solve human’s energy demand. Several technologies have been proposed but yet there are few commercial concepts that have been connected to the grid. The floating wave energy converters (WECs) will have an important role in the supply of electricity in the future. But there are several challenges in their designs on systems and component levels that need to be overcome and solved. There are also challenges related to installation and maintenance. The current paper presents and discusses examples of challenges on component and systems level, with reference to floating WECs. One specific concept is studied in detail with an emphasis on mooring design, fatigue life of elastic mooring systems and umbilical cables, power performance of individual WECs vs WECs installed in wave parks. The levelized cost of electricity method is used to compare some configurations that have been studied in more detail. Examples of results from numerical simulations and full-scale measurements on a floating heave point-absorber are presented.
Experimental Wave Flume Tests in ROV-Wave Interaction Effects on the Line Tension for a Work Class ROV in Splash Zone
Authors: Lubis Michael Binsar , Kimiaei Mehrdad
Published: October 2021

Integrity and stability of Remotely Operated Vehicle (ROV) when passing through the splash zone is one of the main concerns in the design of an ROV-umbilical system. Due to the lightweight nature of ROV in water, the umbilical experiences repetitive rapid transitions between slack and taut as the ROV travels through the splash zone. These rapid transitions induce tension spikes in the umbilical, namely snap forces, that can endanger the launch and recovery of an ROV. Therefore, it is important to ensure that the tension spikes do not exceed the safe working load of the umbilical.

In this study, launch and recovery of a deep-water work class ROV are experimentally investigated using a 1:10 scaled ROV model through a series of wave flume tests. Different regular and irregular waves are generated in the flume while the ROV model is hung over the flume in four different positions. The tension time-history in the line is measured and recorded using a load cell at the top-end of the line. A simplified numerical model for launch and recovery of the ROV is developed and the numerical results are compared with the experimental ones. It is shown that the presented simplified model can be accurately used for analysis of launch and recovery of the ROV.
Damping Estimation Methods Applied to in Service Measurements of a 350 Metre Container Ship
Authors: Hageman R. B. , Andoniu A. , Benhamou A.
Published: October 2021

Large modern container ships feature an open cross section which results in a low stiffness of the vessel to global hull excitation. The contribution of whipping is a significant portion of the overall acceleration and stress response of such a vessel. Whipping results in an increase of the maximum hull girder bending moment experienced by the vessel as well as an increase in the fatigue accumulation of critical details.

In this research, we present damping estimates based on in-service measurements from a container ship. An array of accelerometers was used to derive the first three vertical and first twist vibration modes. The flexural vibrations were isolated using two different methods: first, the Enhanced Frequency Domain Decomposition and secondly, the time domain Stochastic Subspace Identification. Both methods were applied to four representative voyages of the vessel covering a variety of environmental and loading conditions.

On the two- and three-node vertical vibration modes, consistent results between both methods have been obtained. Both the four-node vertical vibration mode and the twist mode showed larger deviations between the two methods. On the vertical vibration modes, the damping is between 0.5 and 2%. On the twist modes, the damping is significantly larger at 5% and up. A correlation between the combined damping and the significant wave height was observed for the different flexural modes.
The Fundamental Research on AI Prediction and Determination of Control Force for Maximizing the Power Generation of PA-WEC in Irregular Waves
Authors: Murai Motohiko , Sakamoto Sho
Published: October 2021

Marine renewable energy is expected as an alternative energy source to fossil fuel. Wave energy is one of the marine renewable energy. The subject of this paper is maximizing power generation by a Point Absorber Wave Energy Converters (PA-WEC) in irregular waves. In the previous study on maximizing the power generation by one of the authors, it has been shown the theoretical solution of the time-domain control force in irregular waves which are defined by superposing regular waves components. That is, if the PA-WEC can simultaneously understand the irregular incident waves as multi certain regular wave components, it can be decided the control force for maximizing the power generation. On the other hand, it is quite difficult to predict precisely and simultaneously the component of coming irregular waves to a PA-WEC installed in the ocean.

In the recent, Artificial Intelligence (AI) and machine learning technology progress rapidly. In the machine learning system, because reading huge data with the relation among them, sometimes it finds out the path connecting A matter and B matter without visible theoretical or logical relations. In this case, the quality of a training data is quite important for accuracy or certainty of the efficient prediction.

In this paper, we examine the possibility of applying AI to predict and decide the control force for maximizing the power generation of the PA-WEC in irregular waves. Some of the results given by the AI has been quite close to the theoretical answer in irregular waves. Through the examination, we investigate and discuss the best or the effective combination of training data sets which are based on the theoretical situation in known waves.
Torsion Failures in Handling Operations for Power Cables, Umbilicals and Flexible Pipes
Authors: Mainçon Philippe , Longva Vegard
Published: October 2021

Over the past 10 years, SINTEF has investigated, or been informed about, a range of torsion failures in cables, umbilicals or flexible pipes. These failures have occurred while the flexible products were being transported along a route during production, loadout, installation. One failure occured during operation. There are no guidelines on how to minimize the risk of such failures. This may be attributed to a lack of knowledge in the industry about the mechanisms that cause torsional moments to appear. Further, some buckling patterns of the components of a flexible product under excessive torsion, closely resemble patterns caused by excessive bending or compressive load, so that some torsion-induced failures are wrongly attributed. Hence, there is a need to increase the knowledge and awareness of torsion failures in the industry. Previous papers by the authors have considered some of the mechanisms that lead to the appearance of torque in handling operations. The present paper is a continuation which focuses on torque-induced failure modes. It begins by providing a systematic nomenclature for the description of torsion kinematics. It then provides a qualitative description of known torque-induced failure modes. The literature provides some models for torque-induced failures, as well as models of component failures due to excessive bending or compression of the flexible product, which are also relevant for the study of torsion. These are reviewed, and their relevance to torsion-induced failures are discussed. Knowledge gaps and challenges are highlighted.
A Scheme of Radial Basis Function Interpolation Based on Partition of Unity Method for FSI Boundary Data
Authors: Min Yu , Xuan Zhang , Tingqiu Li , Yongou Zhang
Published: October 2021

For Fluid-Structure Interaction (FSI) analysis, Radial Basis Functions (RBF) interpolation is very effective for data transfer between fluids and structures because it can avoid interface mesh mismatches that make it difficult to transfer data. However, one of the main drawbacks of conventional RBF interpolation is the computational cost associated with solving linear equations, as well as the corresponding running times. In this paper, a scheme of RBF interpolation based on the Partition of Unity Method (RBF-PUM) is proposed to handle a large amount of FSI boundary data with the aim of striking a balance between computational accuracy and efficiency. And a cross-validation technique is coupled with RBF-PUM, for the purpose of searching for the optimal value of shape parameter related to RBF interpolation. The scheme basically focuses on two parts, one of which is how to partition the fluid domain of node points into a number of subdomains or patches, and the other is how to efficiently exploit the techniques that are applied to reduce the interpolation error locally and globally. Numerical experiments show that compared to the CSRBF method and the greedy algorithm-based RBF method, RBF-PUM significantly improves the computational efficiency of the interpolation and the computational accuracy is relatively competitive.
Failure Modes and Rules Related to the Yield-to-Tensile Strength Ratio in Steel Structures
Authors: Wong Wei Jun , Walters Carey L.
Published: October 2021

Upper limits on the ratio of the yield strength to the tensile strength (σy/σu ratio) and lower limits on the fracture elongation εf are present in various offshore, maritime and civil engineering rules, standards and specifications for steel structures as a provision for the minimum material ductility and toughness which ensures sufficient structural ductility. In other instances, the design yield stress to be adopted in strength calculations is reduced from its nominal value if the σy/σu ratio exceeds a certain limit. Such requirements deter the use of high strength steels (nominal σy higher than 690 MPa), which inherently have a high σy/σu ratio. To guide subsequent efforts towards optimised and scientifically grounded σy/σu limits and wider application of high strength steels, this paper first presents an overview of the current provisions in engineering practice relating to the σy/σu ratio and structural ductility, and it then discusses the key underlying failure mechanisms to which these ductility requirements are relevant: tensile strain localization, yielding and localization precipitated by stress concentrations, localization of plastic bending hinges and ductile fracture. The reasoning behind the current provisions, the findings of previous research concerning the requirements, and the key potential areas for future research are highlighted.
Assessment of Wind and Wave High-Resolution Forecasts During High-Energy Weather Events in the Brazilian Coast
Authors: Chagas F. M. , Rachid B. R. F. , Ambrosio B. G. , Luz A. A. , Gramcianinov C. B. , Serrao P. F. , Camargo R. , Siegle E.
Published: October 2021

We present a high-resolution metocean forecast model (Aimar), which provides 24/7 results for the Brazilian coast. The model integrates global model boundary conditions and detailed coastal models, especially for complex geometry areas near ports and major coastal cities. The aim of this paper is to assess the forecast reliability and to present model data compared to in-situ measurements under high energy weather events. Mean wind velocity and direction were investigated during the occurrence of an extratropical cyclone near Brazilian coast. The model has been assessed by comparing its results to two specific events, one for winds and one for waves. Results of the tested wind event show that Aimar results predict the high energy winds in advance of 5 days, while NCEP’s Global Forecast System Ensemble (GFSe) predicted the same event in advance of 2–3 days, for the region of Santos city. Results of the tested wave event show that Aimar forecasts properly represent the wave propagation for complex geometry coasts. The high-resolution coastal model could predict the nearshore state of sea agitation caused by the passage of a cold front. Model agreement with in-situ wave measurements adjacent to Rio de Janeiro-RJ city were considered Excellent and Good, according to statistical parameters R and RMAE. These results show that high-resolution coastal forecast models can be applied to increase the efficiency, resource uses and reduce the risks for marine operations and engineering works.
An Experimental and Numerical Analysis of Gap Resonance Applicable for FLNG Side-by-Side Offloading
Authors: Nwafor Jideofor Collins , Hu Zhiqiang
Published: October 2021

The present research focuses on the experimental and numerical analysis of nonlinear gap resonance which can occur for two side-by-side configured vessels during the offloading operation of Liquified Natural Gas (LNG). The proximity of the FLNG (Floating Liquefied Natural Gas) facility and LNGC (Liquified Natural Gas Carrier) brings about the formation of a long narrow gap region between the two vessels. The model test was carried out in a wave flume with vessels of different sizes to obtain the resonance response at different locations in the gap region with the effects of gap distances and vessel drafts in incident waves of different wave frequencies and wave directions analysed. It was found that certain model configurations produce increased wave amplification between the vessels, these were highlighted and presented and have the possibility of being predicted to prevent the occurrence. The numerical analysis was carried out with the potential flow solver SIMA in the time domain and a calibrated damping factor was assigned to suppress the overestimated wave elevation in the narrow gap region.
Hull Form Optimization for a 62000DWT Heavy Lift Multi-Purpose Vessel
Authors: Jiang Shuhui , Zhang Li , Chen Weimin
Published: October 2021

A new optimized hull form was proceeded based on a parent ship 60000 DWT bulk carrier. The goal of optimization is to obtain better resistance performance in the loading conditions of scantling draught and design draught. Firstly, the numerical simulation of the parent ship was carried out, the flow field information around the hull was analyzed, the area of high or low pressure was checked, and the area was optimized to make the pressure distribution more uniform. At the same time, the bow entrance section was optimized to reduce the wave-making resistance, and the length of the run body was lengthened to reduce the flow separation area and the viscous pressure resistance. Aiming at these above optimization objectives, the deformation range of hull form was set by commercial software CAESES, and the total resistance of generated optimized cases was solved by SHIPFLOW and evaluated by STARCCM+ software. To grantee the resistance reduction at both design draught and scantling draught, by using the operation profile optimization method, the resistance weights of scantling draught and design draught were set as 50% respectively, that is, the total resistance of optimized hull form equals 50% resistance of design draught condition and 50% resistance of scantling draught condition. The optimization results of total resistance were compared and analyzed, and the cases with relatively minimum total resistance were obtained. On this basis, the wake field at the propeller disk was optimized either, and finally, the target optimization of hull form was obtained. The numerical results showed that, compared with the parent ship, the total resistance at the design speed of the design draught was reduced by about 1.64%, about 2.10% at the design speed of the scantling draught. The wake distribution on the propeller area was more uniform. The final optimized hull form meets the target requirements.
Development of a Simulation System for Estimating the Impact Force of Tsunami Drift Using the Explicit MPS Method
Authors: Aida Yasuhiro , Ikoma Tomoki , Masuda Koichi
Published: October 2021

When a large-scale tsunami occurs, structures in the coastal area will be destroyed by the impact of tsunami drifts. In the design of tsunami evacuation facilities and petroleum complexes, it is necessary to estimate the impact force of tsunami drift, which varies in size, shape and mass. Although some design equations have been proposed to estimate the impact force of tsunami drift, the impact force varies depending on various conditions such as the draft of the tsunami drifts, the attitude of the collision, the condition of the surrounding flow field, and the rigidity of the structure, etc. No reasonable design equation has been developed yet to meet all these conditions. Therefore, it is necessary to estimate the impact force of tsunami drift by water tank experiments and numerical simulations. In order to simulate the impact of a tsunami drift on a structure by numerical simulation, it is necessary to solve the coupling of fluid, floating object and structure. In this study, we have developed a simulation system that can simulate the impact force of a tsunami drift with the MPS method, which is a kind of particle method. This simulation system introduces an explicit method for pressure calculation, which allows for relatively large scale numerical calculations. In addition, the system is able to reproduce the deformation of structures as an elastic body due to the impact of tsunami drift. In particular, we have introduced an analytical method that allows us to set the computational time step that satisfy the CFL conditions for elastic and fluid particles, respectively, for stable simulation even when there is a large difference between the velocity of fluid particles and the velocity of structural particles caused by elastic waves. As a result of the comparison of the impact force on the cantilevered beam of the tsunami drift with the simulation and the water tank test, the deformation of the structure at the time of impact was reproduced with more than 90% accuracy.
Offshore Wind Turbine Mono-Bucket Foundations in Sand
Authors: Low Han Eng , Zhu Fangyuan , Mohr Henning , Watson Phillip , Erbrich Carl , O’Loughlin Conleth , Bransby Fraser , Randolph Mark , Travasarou Thaleia , O’Connell Daniel
Published: October 2021

Single (or mono) suction buckets have been put forward by others as possible offshore wind turbine (OWT) foundations. This paper presents a series of centrifuge model tests conducted in dense sand to investigate their monotonic response for a range of drainage conditions. The results from the centrifuge tests suggest that the mono-bucket rotational response at large rotation in dense sand is dependent on drainage conditions but does not seem to be affected by the contact condition between the bucket invert and the seabed. A final comparison between results from an equivalent set of uplift tests suggests, however, that multi-bucket foundation systems are likely to be more efficient foundation solutions, although suggestions are made which might improve mono-bucket foundation response.
Cathodic Protection Design Consideration for an Offshore Flexible Riser Connected to an Impressed Current System
Authors: Dequin Thierry , Weldon Clark , Hense Matthew
Published: October 2021

Flexible risers are regularly used to produce oil and gas in subsea production systems and by nature interconnect the subsea production system to the floating or fixed host facilities. Unbonded flexible pipes are made of a combination of metallic and non-metallic layers, each layer being individually terminated at each extremity by complex end fittings. Mostly submerged in seawater, the metallic parts require careful material selection and cathodic protection (CP) to survive the expected service life. Design engineers must determine whether the flexible pipe risers should be electrically connected to the host in order to receive cathodic protection current or be electrically isolated. If the host structure is equipped with a sacrificial anode system, then electrical continuity between the riser and the host structure is generally preferred. The exception is often when the riser and host structure are operated by separate organizations, in which case electrical isolation may be preferred simply to provide delineation of ownership between the two CP systems.

The paper discusses these interface issues between hull and subsea where the hull is equipped with an impressed current cathodic protection (ICCP) system, and provides guidance for addressing them during flexible pipe CP design, operation, and monitoring. Specifically, CP design philosophies for flexible risers will be addressed with respect to manufacturing, installation and interface with the host structure’s Impressed Current Cathodic Protection (ICCP) system. The discussion will emphasize the importance of early coordination between the host structure ICCP system designers and the subsea SACP system designers, and will include recommendations for CP system computer modeling, CP system design operation and CP system monitoring.

One of the challenges is to understand what to consider for the exposed surfaces in the flexible pipes and its multiple layers, and also the evaluation of the linear resistance of each riser segment. The linear resistance of the riser is a major determinant with respect to potential attenuation, which in turn largely determines the extent of current drain between the subsea sacrificial anode system and the hull ICCP system.

To model the flexible riser CP system behavior for self-protection, linear resistance may be maximized, however the use of a realistic linear resistance is recommended for evaluation of the interaction between the host structure and subsea system. Realistic flexible linear resistance would also reduce conservatism in the CP design, potentially save time during the offshore campaign by reducing anode quantities, and also providing correct evaluation of drain current and stray currents.
Lateral Buckling Mitigation of Subsea Pipeline by Temporary Winch Pull
Authors: Le Maout Yann , Cerulli Michele
Published: October 2021

The design process of lateral buckling has gained in maturity over the last ten years. However the design of any required engineered trigger to control the formation of lateral buckles remains open to a wide range of design concepts (like sleeper, buoyancy modules, snake lay or residual curvature method) with sometimes increasing complexity in either engineering, fabrication or installation.

This paper will describe how a lateral deflection initiated by a temporary subsea winch after pipelay can be used as a reliable mitigation with limited impact on the project execution.

The interaction between the winch pull and the pipe soil interaction and the consequences on both the post buckle behaviour and reliability design of the mitigation architecture will be presented. The advantages of this technique (decoupling of construction activities between pipelay and lateral buckling mitigation, standard engineering process, no offset from seabed, no additional permanent equipment) and its limitations (stiff pipeline, detailed pipe soil interaction) will be discussed.

The operational feedback from several flowlines designed, installed and operated with this winch pull mitigation will be reviewed and the main lessons learnt will be highlighted.

It can be concluded that this temporary subsea winch pull is an interesting and cost effective option for lateral buckling initiation of subsea pipelines.
Experimental Study of Hydraulic Sealability and Shear Bond Strength of Cementitious Barrier Materials
Authors: Kamali Mohammadreza , Khalifeh Mahmoud , Eid Elsayed , Saasen Arild
Published: October 2021

In this experimental study, two different cementitious materials including (i) a class of expansive cement that is currently used for P&A operations, and (ii) a non-cement-based naturally occurring rock, known as geopolymer are selected to examine the hydraulic bond strength and shear bond strength. Clean machined steel and rusty corroded steel were selected to represent the casing. The test samples were cured at 90 °C, which is considered as bottom-hole static temperature (BHST), and under elevated pressure of 17.2 MPa for one week.

The hydraulic sealability of the barrier materials tested up to 3.4 MPa of differential pressure. The results indicated that additives used in slurry preparation have an impact on the hydraulic sealability of the material. Additionally, the rusty corroded streel provided a better hydraulic sealability comparing to the clean machined steel for the same cementitious material.

The shear bond strength test was performed by running the push-out test. According to the present test observations, no correlation was found between the shear bond and hydraulic bond strength of different barrier materials. The geopolymer showed the lowest shear bond strength, while it provided the highest hydraulic sealability.