bluuebunny/crossref_metadata_2025 huggingface dataset:
Conduction abnormalities and role of cardiac pacing in cardiac amyloidosis: A systematic review
Authors: Alreshq Rabah , Tugal Derin , Siddiqi Omar , Ruberg Frederick
Published: October 2021

Cardiac amyloidosis (CA) is an increasingly recognized cause of heart failure, characterized by extracellular deposition of insoluble protein fibrils leading to progressive myocardial dysfunction. The most common types of cardiac amyloidosis are immunoglobin light‐chain (AL) and transthyretin (ATTR). Conduction abnormalities are commonly encountered among patients with cardiac amyloidosis and are an important cause of morbidity and mortality. Abnormalities range from infra‐Hisian intraventricular conduction delay and bundle branch block to complete atrioventricular block. Pacemaker placement in CA patients follows established guidelines, similar to those for patients without CA, with generally good efficacy. The role and appropriate timing of pacemakers for primary prevention of brady‐arrhythmias in CA remains uncertain. While biventricular (BiV) pacing has been shown to improve clinical outcomes in patients with systolic heart failure without CA, there are few data examining the utility of BiV pacing in patients with CA. With the advent of effective treatments for AL and ATTR, appropriate application of pacing is important to support patients with CA and conduction disease through therapeutic trials. This systematic review summarizes the current literature examining the utility of pacing in CA.
The importance of sustained junctional tachycardia following cessation of radiofrequency current delivery in slow pathway ablation
Authors: Malekrah Alireza , Asgary Nader , Fattahian Alireza , Amirabadi Bahamin
Published: October 2021

Background

Apart from junctional rhythms during slow pathway ablation, there is limited knowledge about the junctional tachycardia persisting following ablation cessation. This study is conducted to determine the characteristics and significance of this rare arrhythmia.

Methods and results

This study was done on 487 patients with AVNRT undergoing the radiofrequency ablation. The RF delivery‐induced Supraventricular Tachycardia, persisting for a few minutes following the termination of ablation (post‐ablation SVT) was investigated in this research. Atrial Overdrive Pacing (AOP) was applied to the post‐ablation SVT to distinguish AVNRT from Junctional Tachycardia(JT). A total of 2337 RF‐current deliveries were applied, and post‐ablation SVT was observed in 81 of them. According to the electrophysiological studies, five of them (in five separate cases) were definitely diagnosed as JT. The overall incidence of post‐ablation JT was about 1% of all patients. In these cases, RF energy was applied to the posteroseptal region and roof of the proximal coronary sinus. The mean Cycle Length (CL) of JTs was equal to 446 ±67ms. Following post‐ ablation JT termination, four cases met endpoints of successful ablation, demonstrating a positive predictive value of 80%. Atrioventricular (AV) block did not occur in any of the cases and reappearance of JT was not observed during procedure or mean follow‐up period of 19.8 ± 8.4 months.

Conclusions

Post‐ablation JT is probably a transient Ischemia‐induced arrhythmia that does not require further ablation. Thus, it is recommended to differentiate between the AVNRT and JT in post‐ablation arrhythmias to avoid unnecessary RF application.
Primary cutaneous lymphomas in children: A prospective study from the Spanish Academy of Dermatology and Venereology (AEDV) Primary Cutaneous Lymphoma Registry
Authors: Torre‐Castro Juan , Estrach Teresa , Peñate Yeray , Acebo Elvira , Fernández de Misa Ricardo , Blanes Mar , Suh‐Oh Hae Jin , Botella‐Estrada Rafael , Torrelo Antonio , García‐Doval Ignacio , Machan Salma ,   RELCP
Published: October 2021

Background/Objectives

Primary cutaneous lymphomas are rare in pediatric patients. The clinical and histopathological manifestations may differ from those in adults. Due to their low frequency and the insidious clinical picture, the diagnosis is usually delayed. The Spanish Primary Cutaneous Lymphoma Registry was initiated in 2016 as a multicenter registry that would allow better insight into the epidemiological, clinical, histopathological, and treatment response characteristics of patients with primary cutaneous lymphomas.

Methods

We conducted a prospective observational cohort study of primary cutaneous lymphomas in pediatric patients participating in the Spanish Academy of Dermatology and Venereology (AEDV) Primary Cutaneous Lymphoma Registry.

Results

At the time of the analysis, 10 patients under 18 years of age out of 799 all‐age cases (1.25%) had been included in the registry (7 males, 3 females). The mean age at diagnosis was 9.7 years (SD: 4.8). Seven (70%) had mycosis fungoides, 2 of them had the folliculotropic variant; and 3 (30%) had primary cutaneous marginal zone B‐cell lymphoma.

Conclusions

Primary cutaneous lymphomas are extremely rare in pediatric patients and usually have a good prognosis. Therefore, a high level of suspicion is necessary for the diagnosis. We suggest management by experienced physicians and follow‐up into adulthood.
Infantile hemangioma affecting the iris
Authors: Robertson Susan J. , Elder James E. , Bekhor Philip S.
Published: October 2021

An infant girl developed a hemangioma affecting her left iris concurrently with diffuse cutaneous infantile hemangiomas from day 2 of life. Intraocular hemangiomas are rarely reported and are usually associated with neonatal hemangiomatosis, the presence of which indicates a high risk for visceral lesions. This striking case highlights the unusual clinical presentation of iris hemangioma and demonstrates the importance of conducting visceral screening when faced with these lesions. Oral propranolol was commenced and resulted in rapid improvement of all lesions without complication.
Whither rice health in the lowlands of Asia: Shifts in production situations, injury profiles, and yields
Authors: Savary Serge , Willocquet Laetitia , Castilla Nancy , Nelson Andy , Shankar Singh Uma , Kumar Jatinder , Teng Paul S.
Published: October 2021

Emphasizing connectedness among the many elements of plant‐based systems that are collectively addressed in One Health is a logical outcome of debates generated by the International Year of Plant Health. The notion of One Health was implemented through the joint use of the concepts of production situation (PS)—the “rice way of life”—and injury profile (IP)—rice health (pathogens, animal pests, and weeds)—in a population of 1051 rice farmers’ fields surveyed from 1987 to 2011. Seven associated PSs and nine IPs are characterized. An ending Green Revolution (Period 1) and a post‐Green Revolution (Period 2) are considered. Major changes in PSs and IPs occurred, with increased mineral fertilizer inputs, pesticide applications, and landscape uniformity, along with shortening fallow periods, and dropping labour. Increases or decreases in some injuries lead to shifts in IPs towards more frequent bacterial, flower, and panicle diseases. Yield gain between the two periods was marginal but yield losses to IPs remained unchanged. Yet there was an increase by 77.0%, 21.6%, and 439% for insecticides, herbicides, and fungicides, respectively, along with a 27.9% increase in mineral fertilizer inputs. Total factor productivity in rice production dropped by over 40% during the 24 intervening years, not accounting for the long‐term effects of these changes on soil fertility, biodiversity, and scarcer water resource. These results call for urgently required reassessment of public efforts to safeguard these agrosystems that are of critical importance economically, socially, and culturally for roughly half the world's population.
Productivity versus drought adaptation in olive leaves: Comparison of water relations in a modern versus a traditional cultivar
Authors: Barzilai Oded , Avraham May , Sorek Yonatan , Zemach Hanita , Dag Arnon , Hochberg Uri
Published: October 2021

The physiological traits that set the tradeoff between productivity and drought adaptation in plants are still under debate. To reveal these traits, we compared the water relations of two olive (Olea europaea) cultivars: “Barnea”—a highly productive modern cultivar; and “Souri”—a drought‐adapted traditional cultivar. We hypothesized that Souri has lower hydraulic conductivity and lower hydraulic vulnerability. The hypothesis was tested at the leaf level. The soil volumetric water content (θ), stem water potential (ΨS), and gas exchange were measured in both cultivars while they dried until a significant reduction in their maximal photochemical potential (Fv/Fm < 0.6) was obtained. Additionally, pressure–volume relations, leaf hydraulic vulnerability, and the petiole xylem architecture were evaluated. To our surprise, Souri's leaf hydraulic conductivity was more vulnerable to low ΨS, approaching zero at −8 MPa compared with <−10 MPa in “Barnea.” At the same time, Souri's higher osmotic content and cell rigidity enabled it to sustain 1.4 MPa lower ΨS, while maintaining near optimal (Fv/Fm). However, both cultivars significantly reduced their Fv/Fm (<0.6) at the same θ, suggesting that the capability to sustain a low θ is not the issue. Instead, Souri's lower transpiration enabled it to withstand a longer drought while avoiding low θ. Barnea's larger xylem vessels and hydraulic conductivity supported higher stomatal conductance (gs) and assimilation rate, which nurtured its higher productivity but resulted in quick depletion of θ. These results suggest that hydraulic resistance or the ability to sustain low θ do not set the tradeoff between productivity and drought adaptation in olive leaves.
Negative effects of long‐term exposure to salinity, drought, and combined stresses on halophyte Halogeton glomeratus
Authors: Lu Yan , Zhang Bo , Li Lei , Zeng Fanjiang , Li Xiangyi
Published: October 2021

Plants are subjected to salt and drought stresses concurrently but our knowledge about the effects of combined stress on plants is limited, especially on halophytes. We aim to study if some diverse drought and salt tolerance traits in halophyte may explain their tolerance to salinity and drought stresses, individual and in combination, and identify key traits that influence growth under such stress conditions. Here, the halophyte Halogeton glomeratus was grown under control, single or combinations of 60 days drought and salt treatments, and morphophysiological responses were tested. Our results showed that drought, salinity, and combination of these two stressors decreased plant growth (shoot height, root length, and biomass), leaf photosynthetic pigments content (chlorophyll a, b, a + b and carotenoids), gas exchange parameters (Net photosynthesis rate [PN], transpiration rate [E], stomatal conductance [gs]), and water potential (ψw), and the decreases were more prominent under combined drought and salinity treatment compared with these two stressors individually performed. Similarly, combined drought and salinity treatment induced more severe oxidative stress as indicated by more hydrogen peroxide (H2O2) and malondialdehyde (MDA) accumulated. Nevertheless, H. glomeratus is equipped with specific mechanisms to protect itself against drought and salt stresses, including upregulation of superoxide dismutases (SOD; EC 1.15.1.1) and catalase (CAT; EC 1.11.1.6) activities and accumulation of osmoprotectants (Na+, Cl−, and soluble sugar). Our results indicated that photosynthetic pigments content, gas exchange parameters, water potential, APX activity, CAT activity, soluble sugar, H2O2, and MDA are valuable screening criteria for drought and salt, alone or combined, and provide the tolerant assessment of H. glomeratus.
ACC deaminase‐producing Brevibacterium linensRS16 enhances heat‐stress tolerance of rice (Oryza sativa L.)
Authors: Choi Jeongyun , Roy Choudhury Aritra , Walitang Denver I. , Lee Yi , Sa Tongmin
Published: October 2021

The rapid rise in global temperature has adverse effects on rice productivity. The lack of eminent resources for heat stress alleviation is threatening the agricultural sector. Heat stress alleviation by endophytic plant growth‐promoting bacteria (PGPB) can be a sustainable and eco‐friendly approach. The present study was conducted to check the colonization of Brevibacterium linens RS16 producing ACC (1‐aminocyclopropane‐1‐carboxylate) deaminase in the rice endosphere and to characterize its efficiency in enhancing stress tolerance. The ethylene emission pathway, reactive oxygen species (ROS) concentrations, proline accumulation, expression of glutathione S‐transferase (GST), and small heat shock proteins (sHSPs) were monitored at two different levels of heat stress (40°C and 45°C). Bacterial inoculation decreased ethylene emission levels by 26.9% and 24.4% in rice plants exposed to 40°C and 45°C, respectively, compared with the non‐inoculated plants. B. linens RS16 also enhanced the expression profiles of glutathione S‐transferase. The collective effect of GST expression profiles and decrease in ethylene emission due to bacterial ACC deaminase activity subsequently resulted in a decrease in ROS concentrations. Additionally, HSP16 and HSP26 increased expression in heat‐stressed plants inoculated with B. linens RS16 resulted in enhanced stress tolerance (i.e., lesser proline accumulation) than non‐inoculated plants. Hence, this study demonstrates the bacteria‐mediated tolerance against heat stress by regulating the ethylene emission pathway and upregulating antioxidant enzymes and heat shock proteins.
Laryngeal hypersensitivity and abnormal cough response during mannitol bronchoprovocation challenge
Authors: Lee Joy Wei‐Yan , Tay Tunn Ren , Borg Brigitte M. , Sheriff Neha , Vertigan Anne , Abramson Michael J. , Hew Mark
Published: October 2021

Background and objective

Inhalational challenge with dry mannitol powder may potentially induce cough by two mechanisms: airway bronchoconstriction or laryngeal irritation. This prospective observational study investigated laryngeal and bronchial components of cough induced by mannitol challenge.

Methods

We recruited consecutive patients referred for clinical mannitol challenge. The Newcastle Laryngeal Hypersensitivity Questionnaire (LHQ) was administered. Throughout testing, coughs were audio‐recorded to derive a cough frequency index per time and dose of mannitol. Relationships between cough indices, laryngeal hypersensitivity and bronchial hyperresponsiveness (BHR) were examined. Participants were classified by cough characteristics with k‐means cluster analysis.

Results

Of 90 patients who underwent challenge, 83 completed both the questionnaire and challenge. Cough frequency was greater in patients with abnormal laryngeal hypersensitivity (p = 0.042), but not in those with BHR. There was a moderate negative correlation between coughs per minute and laryngeal hypersensitivity score (r = −0.315, p = 0.004), with lower LHQ scores being abnormal. Cluster analysis identified an older, female‐predominant cluster with higher cough frequency and laryngeal hypersensitivity, and a younger, gender‐balanced cluster with lower cough frequency and normal laryngeal sensitivity.

Conclusion

Cough frequency during mannitol challenge in our cohort reflected laryngeal hypersensitivity rather than BHR. Laryngeal hypersensitivity was more often present among older female patients. With the incorporation of cough indices, mannitol challenge may be useful to test for laryngeal hypersensitivity as well as BHR.
Breather solutions for a quasi‐linear ‐dimensional wave equation
Authors: Kohler Simon , Reichel Wolfgang
Published: October 2021

We consider the ‐dimensional quasi‐linear wave equation on that arises in the study of localized electromagnetic waves modeled by Kerr‐nonlinear Maxwell equations. We are interested in time‐periodic, spatially localized solutions. Here is even with and with and the delta‐distribution supported in 0. We assume that 0 lies in a spectral gap of the operators on for all together with additional properties of the fundamental set of solutions of . By expanding into a Fourier series in time, we transfer the problem of finding a suitably defined weak solution to finding a minimizer of a functional on a sequence space. The solutions that we have found are exponentially localized in space. Moreover, we show that they can be well approximated by truncating the Fourier series in time. The guiding examples, where all assumptions are fulfilled, are explicitly given step potentials and periodic step potentials . In these examples, we even find infinitely many distinct breathers.
Correlation of myeloid‐derived suppressor cells with C‐reactive protein, ferritin and lactate dehydrogenase levels in patients with severe COVID‐19
Authors: Emsen Ayca , Sumer Sua , Tulek Baykal , Cizmecioglu Hilal , Vatansev Husamettin , Goktepe Mevlut Hakan , Kanat Fikret , Koksal Yavuz , Arslan Ugur , Artac Hasibe
Published: October 2021

The novel coronavirus disease 2019 (COVID‐19) remains a global health emergency, and understanding the interactions between the virus and host immune responses is crucial to preventing its lethal effects. The expansion of myeloid‐derived suppressor cells (MDSCs) in COVID‐19, thereby suppressing immune responses, has been described as responsible for the severity of the disease, but the correlation between MDSC subsets and COVID‐19 severity remains elusive. Therefore, we classified patients according to clinical and laboratory findings—aiming to investigate the relationship between MDSC subsets and laboratory findings such as high C‐reactive protein, ferritin and lactate dehydrogenase levels, which indicate the severity of the disease. Forty‐one patients with COVID‐19 (26 mild and 15 severe; mean age of 49.7 ± 15 years) and 26 healthy controls were included in this study. MDSCs were grouped into two major subsets—polymorphonuclear MDSCs (PMN‐MDSCs) and monocytic MDSCs—by flow cytometric immunophenotyping, and PMN‐MDSCs were defined as mature and immature, according to CD16 expressions, for the first time in COVID‐19. Total MDSCs, PMN‐MDSCs, mature PMN‐MDSCs and monocytic MDSCs were significantly higher in patients with COVID‐19 compared with the healthy controls (P < .05). Only PMN‐MDSCs and their immature PMN‐MDSC subsets were higher in the severe subgroup than in the mild subgroup. In addition, a significant correlation was found between C‐reactive protein, ferritin and lactate dehydrogenase levels and MDSCs in patients with COVID‐19. These findings suggest that MDSCs play a role in the pathogenesis of COVID‐19, while PMN‐MDSCs, especially immature PMN‐MDSCs, are associated with the severity of the disease.
Identification of the novel HLA‐A*30:181 allele by next‐generation sequencing
Authors: Troiano Maria , Giustiniani Paola , Di Luzio Andrea , Bianculli Antonio Giuseppe , Andreani Marco
Published: October 2021

HLA‐A*30:181 differs from HLA‐A*30:01:01 by one nucleotide substitution in Exon 4832 G to A.
Discovering transition patterns among OpenStreetMap feature classes based on the Louvain method
Authors: Zhao Yijiang , Yang Wentao , Liu Yizhi , Liao Zhuhua
Published: October 2021

Numerous studies have shown that OpenStreetMap (OSM) data can achieve high positional quality. However, the thematic attributes of OSM objects can be modified several times, which has a large impact on semantic heterogeneity. Identifying transition patterns within OSM feature classes is an important preliminary step for the tag recommendation algorithm, which can reduce the number of modifications and enhance the efficiency of OSM data updates. In this article, we propose an approach for discovering transition patterns among OSM feature classes. We first produced the transition matrix of feature classes and then developed a graph. Next, the Louvain method for community detection was utilized to cluster the feature classes. OSM data from Indiana, USA, and the Azores, Portugal, were used for our experiments. Some transition patterns were discovered: (1) many feature classes with the most transitions are the same in both datasets and most transitions occur in road‐related feature classes; (2) people tend to tag general classes if they are unsure of the specific classes of tagged objects; and (3) most class transitions occurred as a result of volunteers improving the specificity and precision of feature classes. Moreover, consistently confusing concept pairs were identified.
The red flower wintersweet genome provides insights into the evolution of magnoliids and the molecular mechanism for tepal color development
Authors: Shen Zhiguo , Li Wenying , Li Yanli , Liu Meilan , Cao Heping , Provart Nicholas , Ding Xin , Sun Meng , Tang Zhenghui , Yue Changping , Cao Yunpeng , Yuan Deyi , Zhang Lin
Published: October 2021

Wintersweet (Chimonanthus praecox) is one of the most important ornamental plants. Its color is mainly determined by the middle tepals. However, the molecular mechanisms underlying the intriguing flower color development among different wintersweet groups are still largely unknown. In addition, wintersweet belongs to magnoliids, and the phylogenetic position of magnoliids remains to be determined conclusively. Here, the whole genome of red flower wintersweet, a new wintersweet type, was sequenced and assembled with high quality. The genome comprised 11 super‐scaffolds (chromosomes) with a total size of 737.03 Mb. Based on the analyses of the long branch attraction, incomplete lineage sorting, sparse taxon sampling, and other factors, we suggest that a bifurcating tree may not fully represent the complex early diversification of the angiosperms and that magnoliids are most likely sister to the eudicots. The wintersweet genome appears to have undergone two whole‐genome duplication (WGD) events: a recent WGD event representing an independent event specific to the Calycanthaceae and an ancient WGD event shared by Laurales. By integrating genomic, transcriptomic, and metabolomic data, CpANS1 and the transcription factor CpMYB1 were found to play key roles in regulating tepal color development, whereas CpMYB1 needs to form a complex with bHLH and WD40 to fully perform its regulatory function. The present study not only provides novel insights into the evolution of magnoliids and the molecular mechanism for flower color development, but also lays the foundation for subsequent functional genomics study and molecular breeding of wintersweet.
A Study of Thermal Decomposition and Kinetic Evaluation of Boron Blended Flash Powder Composition
Authors: Azhagurajan A. , Prakash L. , Jeyasubramanian K.
Published: October 2021

Herein, the thermal characteristics of flash powders of different combinations of potassium nitrate, sulfur, aluminum, and boron are reported. From the literature, it is identified that boron implements lack of sensitiveness to flash powder mixture, which promotes safety during the manufacturing process. But the thermal behavior of the boron blended compositions remains a mystery. Hence, various combinations of flash powder compositions are prepared by keeping the % of KNO3 and % of S constant, and gradually 23% of aluminum is reduced (23% to 0) by increasing the quantity of boron (0% to 23%) in 19 trials and are subjected to thermogravimetric analysis (TGA)/differential scanning calorimetric (DSC) analysis individually. The TGA and the DSC analysis reveals that the 65.65% replacement of aluminum with boron mixture shows predominant characteristics which is suitable for fireworks. Also, the reaction kinetics and the critical ignition temperature are calculated for the optimum composition. The performance of the fireworks product is checked with varying quantities to meet out the optimum quality.
Modeling of Soft Robotic Grippers Integrated With Fluidic Prestressed Composite Actuators
Authors: Zhou Yitong , Headings Leon M. , Dapino Marcelo J.
Published: October 2021

Soft robotic grippers can gently grasp and maneuver objects. However, they are difficult to model and control due to their highly deformable fingers and complex integration with robotic systems. This paper investigates the design requirements as well as the grasping capabilities and performance of a soft gripper system based on fluidic prestressed composite (FPC) fingers. An analytical model is constructed as follows: each finger is modeled using the chained composite model (CCM); strain energy and work done by pressure and loads are computed using polynomials with unknown coefficients; net energy is minimized using the Rayleigh–Ritz method to calculate the deflected equilibrium shapes of the finger as a function of pressure and loads; and coordinate transformation and gripper geometries are combined to analyze the grasping performance. The effects of prestrain, integration angle, and finger overlap on the grasping performance are examined through a parametric study. We also analyze gripping performance for cuboidal and spherical objects and show how the grasping force can be controlled by varying fluidic pressure. The quasi-static responses of fabricated actuators are measured under pressures and loads. It is shown that the actuators’ modeled responses agree with the experimental results. This work provides a framework for the theoretical analysis of soft robotic grippers and the methods presented can be extended to model grippers with different types of actuation.
Modeling of Residual Stresses by Correlating Surface Topography in Machining of AISI 52100 Steel
Authors: Liu Chao , He Yan , Li Yufeng , Wang Yulin , Wang Shilong , Wang Yan
Published: October 2021

The residual stresses could affect the ability of components to bear loading conditions and also the performance. The researchers considered workpiece surface as a plane and ignored the effect of surface topography induced by the intermittent cutting process when modeling residual stresses. The aim of this research develops an analytical model to predict workpiece residual stresses during intermittent machining by correlating the effect of surface topography. The relative motions of tool and workpiece are analyzed for modeling thermal-mechanical and surface topography. The influence of dynamic cutting force and thermal on different positions of surface topography is also considered in the analytical model. Then, the residual stresses model with the surface topography effect can be developed in intermittent cutting. The analytical models of dynamic cutting force, surface topography, and residual stresses are verified by the experiments. The variation trend of evaluated values of the residual stress of workpiece is basically consistent with that of measured values. The compressive residual stress of the workpiece surface in highest point of the surface topography is higher than that in the lowest point.
Steel Lazy Wave Riser Optimization Using Artificial Neural Networks and Genetic Algorithm
Authors: Lal Mayank , Sebastian Abhilash , Rana Yashpal
Published: October 2021

Over the past few years, a number of deepwater projects that use steel lazy wave risers have been commissioned or are under development. Steel lazy wave risers have an advantage over steel catenary risers as they offer flexibility of use with a floater having severe motion such as FPSO. They also impart lower loads at the interface with the floater compared to a traditional steel catenary riser, and hence can be used in deeper waters. Therefore, design of steel lazy wave risers has gained importance over the years as exploration of oil happens in ever deeper waters.

In this paper, artificial neural networks and genetic algorithm are used to automatically generate a steel lazy wave riser design. A dataset of optimized designs of steel lazy wave risers for various inputs such as water depth, pipe OD, wall thickness etc. are generated using genetic algorithm. This dataset is used to train a neural network to automatically output a steel lazy wave riser design. The SLWR configuration that is automatically generated can be used as a starting point for conceptual and pre-FEED studies and help engineers come up with an initial SLWR design capturing the basic requirements without going through rigorous analyses. It has potential for cost savings and meeting schedule demands of fast paced projects as it will speed up the steel lazy wave risers’ design.
Depth Control Modelling and Analysis of a Subsea Shuttle Tanker
Authors: Ma Yucong , Sui Dan , Xing Yihan , Ong Muk Chen , Hemmingsen Tor Henning
Published: October 2021

A novel subsea shuttle tanker (SST) concept was recently proposed as a cost-effective alternative to subsea pipelines and tanker ships for liquid CO2 transportation between a source facility and a subsea well. It is envisioned that the SST will be deployed to transport CO2 to marginal subsea fields with an annual CO2 storage capacity less than 1 million metric tons; volumes that do not justify a full subsea field development. The SST is designed to be a fully autonomous underwater vessel with a cargo capacity of over 17,000 metric tons. It is 155 m long and it has a 17 m diameter hull. The vessel may operate at a water depth of between 50 to 200 m in a weather-independent environment. Furthermore, it travels at a slow speed for minimal energy consumption and maximal range. During the offloading process, the SST will approach the subsea well and land on the seabed just outside the safety radius of the well. After that, a remotely operated vehicle (ROV) will mate the offloading flowline to the SST, and the offloading process will start. The landing sequence is technically challenging for various reasons and warrants detailed analysis. First, the SST would have limited manoeuvrability due to the large inertia of the vessel and low effectiveness of the hydroplanes to provide steering at low speeds. Second, during the final phase before the SST lands, seabed boundary effects will intensify and lead to increased non-uniform, time-varying and drag-dominated load-effects. Third, the impact forces during landing should be minimised to allow for the lowest design load. Solving these technical challenges is crucial to meet SST’s design goals of having the least possible control appendices for maximum efficiency/range, and minimal structural weight for the largest cargo capacity. This paper will describe the development of a fully coupled 2D planar model that considers the most relevant load-effects. This model is developed with the feasibility to implement any control schemes and has the potential to plug observers or control modules in future study. This paper performs open loop test and applies simple control cases to explore the depth control in landing sequence. A feed-forward heading control method that achieves the fastest control response and best path following ability is then proposed based on the results obtained.
Numerical Prediction of 3-D Vortex-Induced Vibration of Catenary Riser In Planar and Non-Planar Flows
Authors: Ma Bowen , Srinil Narakorn
Published: October 2021

Vortex-induced vibration (VIV) is one of the most critical issues in deepwater developments due to its resultant fatigue damage to subsea structures such as risers, pipelines and jumpers. Although VIV effects on slender bodies have been comprehensively studied over decades, very few studies have dealt with VIV modelling and prediction of catenary risers in current flows with varying directions leading to complex fluid-structure interactions. This study advances a numerical model to simulate and predict 3-D VIV responses of a catenary riser in three flow orientations, relative to the riser curvature plane, including concave/convex (planar) and perpendicular (non-planar) flows. The model is described by equations of cross-flow and in-line responses of the catenary riser coupled with the hydrodynamic forces modelled by the distributed nonlinear wake oscillators. A finite difference method is applied to solve the coupled fluid-structure dynamic system. To consider the approaching flow in different directions, the vortex-induced lift and drag forces are formulated by accounting for the effect of flow angle of attack and the riser-flow relative velocities. Results show VIV features of a long catenary riser exhibiting a standing and travelling wave response pattern. VIV response amplitudes and oscillation frequencies are predicted and compared with experimental results in the literature for both straight and catenary risers. Overall results highlight the model capability in capturing the effect of approaching flow direction on 3-D VIV of the curved inclined flexible riser.
Bivariate Regional Frequency Analysis of Sea State Conditions
Authors: Vanem Erik
Published: October 2021

This paper presents a bivariate regional frequency analysis applied to data of extreme significant wave heights and concurrent wave period over an area in the North Atlantic Ocean. It extends previous regional frequency analysis on significant wave height to the bivariate case where the joint distribution of significant wave height and zero up-crossing wave period are analysed. This is believed to be an important extension, as the joint distribution is typically needed for marine design and other ocean engineering applications. The analysis presented in this paper is based on a bivariate index-wave/period approach and assumes a common regional growth curve within homogeneous regions of the overall area. One of the main benefits of performing a regional frequency analysis as opposed to at-site analysis based on data from one location only is that more accurate predictions of extreme conditions can be obtained, due to the increased number of observations that will effectively be available. Moreover, results for locations within the regions where no observations are available can be obtained by interpolation of the index wave/period and utilizing the regional growth curve. This paper outlines the various steps and modelling choices involved in a bivariate regional frequency analysis and presents the results of such an analysis applied to 30 years of data covering the North Atlantic Ocean. Moreover, it is shown how environmental contours can be constructed based on the outcome of the bivariate RFA, corresponding to one particular definition of a bivariate return period.
Experimental Investigation of Aspects Influencing the Level Ice Resistance of Ships With Non-Typical Icebreaking Bow Shapes
Authors: Myland Daniela , Hisette Quentin , Cilkaya Emre , Sefa Özhan Yusuf
Published: October 2021

For non-typical icebreaking ships the hull-ice interaction process in level ice comprises a combination of many different phenomena which is difficult to be described by existing straightforward approaches. In order to gain knowledge about the operability of such non-typical hull shapes in level ice, a study has been carried out to identify and evaluate the level ice resistance as well as its distribution along the hull of ships with non-typical icebreaking bow shapes with high stem and/or small waterline angles. For this purpose, one ship model has been manufactured and instrumented with several multi-axis load cells in the bow region of the waterline as well as with one large six-component load scale between the bow and the stern. Performing resistance model tests at several loading conditions in model ice sheets of different thickness and at multiple speed values allows obtaining relevant information to meet the goals of the study. The developed methodology and the analysis of the measured loads have been described in previous publications. As direct continuation, the present paper focuses on investigation of the ice floe characteristics and its linkage to the ice properties. Moreover, analysis results related to the crushing portion of the total resistance in ice, the friction between ice and ship model hull as well as the ship model motions during ice model testing are presented within the paper.
Machine Learning Approach to Estimate the Diffusion Coefficient of CO2 in Hydrocarbons
Authors: Bagalkot Nikhil , Keprate Arvind
Published: October 2021

Diffusion of the gas into the liquids is a critical part in understanding multiphase systems and engineering applications associated with these multiphase systems. The study couples multiphase pendant drop experiments and computational modelling to calculate the CO2 diffusion coefficient in n-decane. Experiments were carried out at a varied range of pressure and temperature 25–45°C and 25–65 bar. During the experiments, the change in the volume of the hydrocarbon drop due to CO2 diffusion was dynamically measured, and numerical model was developed which used the experimental data to estimate the diffusion coefficient. The current study brings in the capability of machine learning as a replacement of the computational part for prediction of the diffusion coefficient of the process. The feasibility of various machine learning models such as Gradient boosting, Gaussian Process Regression (GPR), k-NN, Decision tree etc. are checked. Firstly different algorithms were trained on the dataset and finally evaluated on the test dataset, using various statistical metrics). Finally, the most accurate algorithm is used as a surrogate model for predicting the diffusion coefficient. The chosen ML algorithm was fairly accurate in predicting the diffusion coefficient with a maximum inaccuracy of 7.5%. Therefore, ML may then be employed as an alternative to experiments and numerical methods. A case study is performed to demonstrate the proposed methodology.
FPSO Mooring Line Failure Detection Based on Predicted Motion
Authors: Saad Amir Muhammed , Schopp Florian , Queiroz Filho Asdrubal N. , Cunha Rodrigo Da Silva , Santos Ismael H. F. , Barreira Rodrigo Augusto , Tannuri Eduardo Aoun , Gomi Edson Satoshi , Costa Anna Helena Reali
Published: October 2021

A failure in the mooring line of a platform, if not detected quickly, can cause a riser system failure, extended production downtime, or even environmental damages. Therefore, integrity management and timely detection of mooring failure for floating platforms are critical. In this paper, we propose a new model for an ANN-based mooring failure detection system. The proposal’s idea is to train a Multilayer Perceptron (MLP) to estimate the platform’s future motion based on its motion’s temporal data without failure. A classifier then indicates whether or not there is a failure in the mooring system based on the difference between the predicted and the measured motion. The results with several tests of the implemented system show that our proposal can correctly predict the motion of the platform in most environmental conditions. The system shows a precision, accuracy and F1-score of 99.88%, 99.99% and 99.94%, respectively, for detecting changes in platform motion in near real-time, quickly signaling a possible breakage of mooring lines.
Evolution of the Stress-Induced Residual Magnetic Field of X70 Pipeline Steel With Multiple Corrosion Defects
Authors: Bao Sheng , Luo Qiang , Zhao Zhengye , Yang Jian
Published: October 2021

The aim of this research is to investigate the correlation between the residual magnetic field (RMF) and multiple corrosion defects in ferromagnetic steels. Specimens of X70 pipeline steel were machined into standard bars with a single corrosion defect, double corrosion defects and triple corrosion defects, respectively. Tensile tests were carried out to detect the RMF signals on the surface of these specimens. The variations of abnormal magnetic changes of the RMF signals with the external loads were investigated and the results showed that the tangential component and the normal component of the RMF signals of three defect patterns presented different shapes. It was found that the RMF signals were capable of capturing the location and the number of defects in pipeline steels. The peak values of the tangential component and the slopes of the normal component were not influenced by the defects number. This research will promote the investigation on the corrosion defect cluster of ferromagnetic steels based on the metal magnetic memory (MMM) technique.
Efficient Harbor Craft Monitoring System: Time-Series Data Analytics and Machine Learning Tools to Achieve Fuel Efficiency by Operational Scoring System
Authors: Tay Zhi Yung , Hadi Januwar , Konovessis Dimitrios , Loh De Jin , Tan David Kong Hong , Chen Xiaobo
Published: October 2021

This paper presents the analysis to reduce carbon emission from tugboat operations by utilizing a proposed unsupervised machine learning operational scoring system. The time-series analysis is performed by transforming data into a common domain for clustering. The data are collected from a tugboat to investigate the correlation between environmental and location data with fuel consumption to achieve fuel efficiency. The relevant parameters that influence the fuel consumption of the tugboat, such as fuel consumption, vessel route, vessel speed and wind metrics are collected from sensors installed onboard the ship and data provider to monitor and to gauge the vessel’s performance. The raw readings are conditioned (data cleaning and data pre-processing) before transformation to Score Dataset: the Raw mass-flowrate readings are cleaned by using the Haar wavelet; the wind raw reading is converted to wind effect data; the Location data is converted to vessel speed data. Together, they form a Score Dataset by applying the time series K-means clustering. The subsequent unsupervised learning identifies the activity labels that describe qualitatively the operations of the vessels and are obtained by using the non-time series K-mean clustering. By using the Hidden Markov Model approach, this paper attempts to explain the stochastic correlation among parameters explained earlier. The correlation is the information of newly discovered knowledge in terms of likelihood matrices, also known as the knowledge base (KB). The KB may be consumed to perform predictions. Hence, it is possible to suggest the optimal ship operation, i.e., speed that produces the optimum fuel consumption. The Score Dataset and clustering that are produced in this paper could also be used in the Artificial Neural Network for future work.
Comparison of the Fatigue Performance of Galvanised M72 Bolts With Design Standard Recommendations
Authors: Johnston Carol , Doré Matthew
Published: October 2021

Now that bolted flanges rather than grouted connections are used to join the transition piece to the monopile in offshore wind turbine towers, many large bolts are being used in applications which subject them to fatigue loads. The bolts in these ring flanges are typically M64 or M72 in size (ie 64mm of 72mm nominal diameter). The fatigue design codes, BS 7608, DNVGL-RP-C203 and Eurocode 3 do provide S-N curves for threaded fasteners, but the reference diameter in those documents is 25mm or 30mm. A thickness correction is provided, to account for larger diameter bolts, but this was originally derived by analysis of the performance of welded joints. It is unclear whether the S-N curves and the recommended thickness correction are appropriate for larger diameter threaded fasteners.

The offshore wind industry usually specifies hot dip galvanised bolts, to provide some corrosion protection in the offshore environment. Again, there is uncertainty over whether the S-N curves in fatigue design standards apply to bolts with a galvanised coating. Since the fatigue design codes provide S-N curves for air, free corrosion or seawater with cathodic protection, it is also unclear which of these should be used to predict the fatigue performance of bolts with a galvanised coating.

In order to provide data to address these uncertainties, hot-dip galvanised, grade 10.9, M72 bolts from two manufacturers were tested in both air and a seawater environment. In order to represent the conditions experienced by bolts in internal ring flanges, the artificial seawater was sprayed onto the bolts during testing. Tests were conducted with a mean stress corresponding to 70% of the specified minimum 0.2% proof strength of the bolts. Tests were also performed in air, on uncoated M72 bolts, and uncoated M64 bolts for comparison.

The results suggest that the current thickness correction in DNVGL RP C203 and BS 7608 is appropriate for M72 bolts.

The results in air from the galvanised bolts were below those from uncoated bolts. Although the galvanised results were above the thickness corrected in-air standard design curves (BS7608 Class X -20%, DNVGL Class G and DNVGL ST 0126 FAT 50), they were below the mean curves, suggesting that the performance of galvanised bolts is slightly lower than the existing recommendations.
Bubbler System Testing in Controlled Environment for Harsh Environment Oil Spill Recovery
Authors: Thodi Premkumar , Talimi Vandad , Burton Robert , Abdi Majid , Bruce Jonathon , Lui Lei , Brown Robert
Published: October 2021

Mechanical recovery techniques are used to clean up oil spills in marine environments; however, their efficiency is challenged when dealing with heavy oil, ice covered water and high sea states. Current mechanical recovery techniques are based on removing oil from the water surface, however, a significant amount of oil could remain in the water column below the surface due to turbulent ocean conditions, the density of heavy oil and oil escaping underneath the booms when the sweeping speed increases. To enhance the oil recovery effectiveness, oil particles in the water column need to be guided to the surface to be recovered by the skimmers. This paper focusses on the development of a test protocol and physical testing in C-CORE’s lab of a bubbler system for enhancing the harsh environment oil spill recovery. Air bubbles produce an upward flow in the water body, which guides the submerged particles to the surface. The air bubbles also attach to the oil particles, leading to an increase in the buoyancy and rate at which oil droplets rise to the surface. By adopting this technique for oil recovery, additional oil particles can be brought to the surface. In the study, the bubbler system was tested in both stationary and advancing conditions with medium and heavy oils. The results of the stationary and advancing tests indicate that the oil recovery ratios can be significantly enhanced by using an optimized bubbler system. Different types and configurations of bubblers were tested by varying the airflow rates and bubbler advancing speeds to determine the optimal solution. The optimal bubbler system has been observed to enhance the recovery ratio from 41.5% to 84.8% with airflow rates ranging from 0.05 to 0.20 CFM/foot. Furthermore, the effective integration of the bubbler system with a mechanical recovery system, its deployment and retrieval in a near field condition were demonstrated during tests in an outdoor tank.