bluuebunny/crossref_metadata_2025 huggingface dataset:
The psychotomimetic ketamine disrupts the transfer of late sensory information in the corticothalamic network
Authors: Qin Yi , Mahdavi Ali , Bertschy Marine , Anderson Paul M. , Kulikova Sofya , Pinault Didier
Published: October 2022

In prodromal and early schizophrenia, disorders of attention and perception are associated with structural and chemical brain abnormalities and with dysfunctional corticothalamic networks exhibiting disturbed brain rhythms. The underlying mechanisms are elusive. The non‐competitive NMDA receptor antagonist ketamine simulates the symptoms of prodromal and early schizophrenia, including disturbances in ongoing and task & sensory‐related broadband beta−/gamma‐frequency (17–29 Hz/30–80 Hz) oscillations in corticothalamic networks. In normal healthy subjects and rodents, complex integration processes, like sensory perception, induce transient, large‐scale synchronised beta/gamma oscillations in a time window of a few hundred ms (200–700 ms) after the presentation of the object of attention (e.g., sensory stimulation). Our goal was to use an electrophysiological multisite network approach to investigate, in lightly anesthetised rats, the effects of a single psychotomimetic dose (2.5 mg/kg, subcutaneous) of ketamine on sensory stimulus‐induced oscillations. Ketamine transiently increased the power of baseline beta/gamma oscillations and decreased sensory‐induced beta/gamma oscillations. In addition, it disrupted information transferability in both the somatosensory thalamus and the related cortex and decreased the sensory‐induced thalamocortical connectivity in the broadband gamma range. The present findings support the hypothesis that NMDA receptor antagonism disrupts the transfer of perceptual information in the somatosensory cortico‐thalamo‐cortical system.
A narrative review of the calcitonin peptide family and associated receptors as migraine targets: Calcitonin gene‐related peptide and beyond
Authors: Garelja Michael L. , Hay Debbie L.
Published: October 2022

Objective

To summarize the pharmacology of the calcitonin peptide family of receptors and explore their relationship to migraine and current migraine therapies.

Background

Therapeutics that dampen calcitonin gene‐related peptide (CGRP) signaling are now in clinical use to prevent or treat migraine. However, CGRP belongs to a broader peptide family, including the peptides amylin and adrenomedullin. Receptors for this family are complex, displaying overlapping pharmacologic profiles. Despite the focus on CGRP and the CGRP receptor in migraine research, recent evidence implicates related peptides and receptors in migraine.

Methods

This narrative review summarizes literature encompassing the current pharmacologic understanding of the calcitonin peptide family, and the evidence that links specific members of this family to migraine and migraine‐like behaviors.

Results

Recent work links amylin and adrenomedullin to migraine‐like behavior in rodent models and migraine‐like attacks in individuals with migraine. We collate novel information that suggests females may be more sensitive to amylin and CGRP in the context of migraine‐like behaviors. We report that drugs designed to antagonize the canonical CGRP receptor also antagonize a second CGRP‐responsive receptor and speculate as to whether this influences therapeutic efficacy. We also discuss the specificity of current drugs with regards to CGRP isoforms and how this may influence therapeutic profiles. Lastly, we emphasize that receptors related to, but distinct from, the canonical CGRP receptor may represent underappreciated and novel drug targets.

Conclusion

Multiple peptides within the calcitonin family have been linked to migraine. The current focus on CGRP and its canonical receptor may be obscuring pathways to further therapeutics. Drug discovery schemes that take a wider view of the receptor family may lead to the development of new anti‐migraine drugs with favorable clinical profiles. We also propose that understanding these related peptides and receptors may improve our interpretation regarding the mechanism of action of current drugs.
Post hoc analysis of clinical trial data and pharmacokinetic data to assess wearing‐off of erenumab within monthly treatment cycle
Authors: Dodick David W. , Blumenfeld Andrew M. , Halker Singh Rashmi B. , Williams Rachel , Zhang Feng , Chen Po‐Wei , Hsu Cheng‐Pang , Peng Cheng , Snellman Josefin , Chehrenama Mahan , Ailani Jessica
Published: October 2022

Background

Treatment wearing‐off has been reported for calcitonin gene‐related peptide‐pathway monoclonal antibodies, including erenumab, specifically in the last week of the monthly dosing cycle.

Objective

We sought to determine the consistency of erenumab effect throughout the monthly treatment cycle.

Methods

In this post hoc analysis of four pivotal double‐blind, randomized controlled studies of erenumab in episodic and chronic migraine, we assessed wearing‐off based on change in weekly migraine days at week 4 versus average over weeks 1–3 in each monthly dosing cycle. Analyses were conducted at each monthly dosing cycle in all patients, in responders (≥50% reduction in weekly migraine days), and in consistent responders (response in ≥2monthly cycles).

Results

There was no evidence of wearing‐off in the full study populations of two global studies (N = 946 and N = 656) and two Japan studies (N = 475 and N = 261). In the full study population, mean change in weekly migraine days at week 4 compared with the average over week 1–3 ranged from 0.15 days improvement to 0.19 days worsening in the placebo group and 0.08 days improvement to 0.20 days worsening in the erenumab groups. A subgroup of responders experienced wearing‐off, but the extent of wearing‐off did not differ between erenumab and placebo groups. The mean change in weekly migraine days at week 4 compared with the average over weeks 1–3 ranged from 0.34 to 0.61 days worsening in the placebo group and 0.27 to 0.78 days worsening in the erenumab groups. Few patients had persistent wearing‐off in ≥2 consecutive monthly treatment cycles. For erenumab‐treated responders, serum erenumab concentrations were similar among patients experiencing wearing‐off and those maintaining response.

Conclusion

No systematic wearing‐off with erenumab was identified. Further research is needed to determine if wearing‐off reported for some patients in clinical practice reflects a true treatment response pattern or normal fluctuations in migraine frequency.
A Legacy of EM Algorithms
Authors: Lange Kenneth , Zhou Hua
Published: October 2022

Nan Laird has an enormous and growing impact on computational statistics. Her paper with Dempster and Rubin on the expectation‐maximisation (EM) algorithm is the second most cited paper in statistics. Her papers and book on longitudinal modelling are nearly as impressive. In this brief survey, we revisit the derivation of some of her most useful algorithms from the perspective of the minorisation‐maximisation (MM) principle. The MM principle generalises the EM principle and frees it from the shackles of missing data and conditional expectations. Instead, the focus shifts to the construction of surrogate functions via standard mathematical inequalities. The MM principle can deliver a classical EM algorithm with less fuss or an entirely new algorithm with a faster rate of convergence. In any case, the MM principle enriches our understanding of the EM principle and suggests new algorithms of considerable potential in high‐dimensional settings where standard algorithms such as Newton's method and Fisher scoring falter.
Interspecific variations in fish occupancy and abundance are driven by niche characteristics in a monsoon climate river basin
Authors: Xia Zhijun , Heino Jani , Liu Fei , Yu Fandong , Xu Chunsen , Hou Miaomiao , Zou Xinhua , Wang Jianwei
Published: October 2022

Aim

The interspecific relationships between species occupancy and abundance have been broadly studied in terrestrial systems; however, the causes underlying this relationship in freshwater fishes remain poorly addressed. The main aims of this study were (a) to examine the occupancy–abundance relationship in 62 fish species in a monsoon climate river; (b) to determine the relative importance of species niche, functional traits and phylogenetic relatedness in shaping the occupancy–abundance relationship.

Location

The Chishui River, the Yunnan‐Guizhou Plateau and the Szechwan Basin, China.

Taxon

Freshwater fishes.

Methods

A linear model was used to test the relationship between distribution and mean abundance across fish species. The outlying mean index analysis was performed to estimate niche breadth and niche position parameters for each fish species. In addition, using principal coordinates analysis, we created four trait vectors describing the similarity of species' traits. Fish phylogeny was obtained from a global molecular phylogenetic tree of actinopterygian fishes. We used a combination of linear models, commonality analyses and boosted regression trees to evaluate the relative effects of the niche metrics, traits and phylogenetic relatedness on occupancy and abundance.

Results

Fish occupancy was strongly (R2 = 0.749) and positively correlated with mean abundance in the Chishui River. Niche parameters, especially niche position, were the main determinants of variation in occupancy (e.g. total contribution of niche position and breadth using commonality analyses: 0.587 and 0.318) and abundance (0.323 and 0.151) across species. Furthermore, traits and phylogeny had little to no effect on fish occupancy (0.034 and 0.037) and abundance (0.021 and 0.003).

Main conclusions

Freshwater fishes in the Chishui River fit the common macroecological pattern of positive relationship between occupancy and abundance. Niche parameters, but not traits and phylogeny, are the primary correlates of riverine fish distribution and abundance.
A unique case of isolated thoracic spinal Rosai‐Dorfman disease related to IgG4
Authors: Terzi Ayşen , Sercan Çiğdem , Şahintürk Fikret
Published: October 2022

Rosai‐Dorfman disease (RDD) is a rare benign histiocytosis usually characterized by massive cervical lymphadenopathy and systemic manifestations. Extranodal, especially spinal involvement, is extremely rare. Our case was deemed worthy of presentation because it was the first reported isolated case of spinal RDD related to IgG4 and mimicked meningioma clinically and radiologically. A case with an intradural extramedullary mass causing neurological compression findings in the thoracic spinal region and radiologically mimicking meningioma is presented. In the histomorphological examination of the resection material, polymorphonuclear leukocytes in the dura, histiocytes showing emperipolesis, an increase in collagenized fibrous connective tissue, and intense lymphoplasmacytic cell infiltration accompanied by obliterative phlebitis were observed. Immunohistochemically, the histiocytic cells were found to be S‐100 protein, CD68, and CD163 positive and CD1a and langerin negative, and more than half of the plasma cells were immunoglobulin‐G4 (IgG4) positive. Although rare, RDD or IgG4‐related meningeal disease should be considered in the differential diagnosis of dural‐based spinal masses that radiologically suggest meningioma. The pathologist should be aware that these two histopathological entities may coexist. To our knowledge, this is the first case of “isolated spinal RDD related to IgG4” reported in the literature.
A systematic review of relationship sacrifices from 2002 to 2021: Moving toward inclusivity
Authors: Curran Melissa A. , Young Valerie J. , Kayabol Nazlı Büşra Akçabozan , Totenhagen Casey J.
Published: October 2022

We conducted a systematic review of research on relational sacrifices in romantic relationships from 2002 to 2021 [N = 115 studies] to answer three questions: Q1: Whose voices and vantage points are represented in the research?; Q2: What types of questions are valued?; Q3: What are the reflections and connections about relational sacrifices that were learned during the review? To address Q1, we coded sample demographics of study participants on geographical location, race/ethnicity, education/income/SES, gender (i.e., gender differences explored and beyond gender binaries), sexual orientation, age, and disability, using a coding system of 1 (exclusion/absence) to 5 (focus on context‐relevant experiences for underrepresented samples). Results for Q1 showed that the most frequent codes were 1 (exclusion/absence) for information about the samples' disability status, education/income/SES, and both codes for gender (i.e., gender differences explored and beyond gender binaries); when demographic information was reported, the most frequent codes were 2 (compensatory addition) for age, sexual orientation, geographical location, and race/ethnicity. To address Q2, we coded for aspects of the study designs and conceptual dimensions of sacrifice. Results for Q2 showed that a majority of the studies in our review used quantitative and close‐ended measures emphasizing behavioral frequency of sacrifice. For Q3, we include our own reflections and connections about relational sacrifices, questioning research methods, and challenging assumptions drawn from existing research to move toward a more inclusive science.
Factors Related to Hearing Complaints Due to Noise on Furniture Workers in Medan City – Indonesia.
Authors: Nanda Novziransyah  , Ira Aini Dania
Published: October 2022

Every workplace has always various potential risk that can affect the health of the workers or can cause work-related illnesses. One of the physical conditions and work environment that is dangerous is noise. The higher intensity of noise and the longer the workers are exposed to noise, the higher the risk of workers experiencing hearing loss. The purpose of this study was to determine the relationship of risk factors with noise due to hearing disorder in furniture workers along Jalan Pahlawan in Medan City, Sumatera Utara Province, Indonesia, 2019.This study was an observational analytic study with a cross sectional research design. This study uses a population of furniture workers along Jalan Pahlawan and using accidental sampling in the sampling method of 30 respondents. Data was carried out by measuring the noise intensity in the work area of ​​furniture production and give questionnaires to 30 respondents who are working. Data analysis techniques used are univariate and bivariate analysis. The results of the study show that there is a relationship between noise intensity and hearing disorder (p=0,001<α=0,05); there is a relationship between the age of the worker and hearing disorder (p=0,000<α=0,05); there is a relationship between period of work with hearing disorder (p=0,025<α=0,05); there is a duration of work relationship with hearing disorder (p=0,010<α=0,05); there is a relationship between the use of ear protector and hearing disorder(p=0.001<α=0,05) in furniture workers along Jalan Pahlawan in Medan City.
Deformation and Springback Behavior of Sheet Metal With Convex-Shaped Surfaces in Heat-Assisted Incremental Bending Process Based on Minimum Energy Method
Authors: Wei Bo , Zhang Feifei , He Kai , Li Zheng , Du Ruxu
Published: October 2022

Three-dimensional sheet metal forming is one of the biggest challenges in the shipbuilding industry. The forming quality of the traditionally applied line heating method depends entirely on the skills of the technicians. Moreover, this approach is inefficient and error-prone. This calls for a need to develop new forming technologies that are easy to control and more efficient. In this paper, a novel forming method called heat-assisted incremental bending is presented. The minimum energy loading path of bidirectional curvature sheet along the direction of Gaussian curvature is adapted to deform the sheet metals with a convex shape surface. Besides, the auxiliary heating method and the auxiliary supporting are exclusively included in the forming process to improve the formability and accuracy. In this study, the convex-shaped sheet metal with large curvature is obtained along the two loading trajectories in two principal curvature directions, respectively. Results proved that using the minimum energy loading trajectory and including the auxiliary supports and heating can reduce the forming force to the greatest extent and effectively reduce the number of stamping points, thus improving the sheet metal forming efficiency and forming accuracy.
Lockable Lower-Limb Exoskeleton Based on a Novel Variable-Stiffness Joint: Reducing Physical Fatigue at Squatting
Authors: Ma Zhuo , Liu Jianbin , Ma Guoyu , Gao Jingshuo , Chen Baojun , Zuo Siyang
Published: October 2022

Some special tasks require human operations and cannot be performed by robots or other autonomous equipment, such as special industrial assembly and surgical procedures in small and crowded spaces. Workers/surgeons in these cases tend to have physical fatigue. In this study, a novel variable-stiffness joint based on positive pressure was proposed, and a torque model was established. The locking torque variation, step response, and energy consumption were evaluated in comparison with a torque motor. A lockable lower-limb exoskeleton based on the variable-stiffness joint was developed, and wearable tests were conducted to evaluate a voice recognition interface and supporting performance. The locking torque of the variable-stiffness joint could be continuously varied from 0 Nm to 26 Nm with the air pressure ranging from 1.6 bar to 5.5 bar. The settling time was 0.328 s in the step response experiment. With a load of 6 Nm, the variable-stiffness joint can realize an energy consumption reduction of 75.01% compared with using a torque motor. Moreover, the lockable lower-limb exoskeleton can realize a 35–60% reduction in the average muscle activation in each subject (aged 22–57) to maintain squatting postures at three different knee angles (paired t-test, P < 0.01). The proposed exoskeleton system has good mobility, low energy consumption, and easy-to-control features, showing great potential in supporting the weight of workers/surgeons during long-term operations.
Analysis and Design of a Novel Compact Three-Degree-of-Freedom Parallel Robot
Authors: Zhou Zhou , Gosselin Clément
Published: October 2022

This paper introduces a novel compact three-degree-of-freedom (DOF) parallel robot that will be used as a leg of a 9-DOF kinematically redundant parallel robot. First, the kinematic model of the robot is established based on geometric constraint conditions. Then, the inverse and forward kinematic problems are solved. The inverse problem is straightforward, while the forward problem can be solved analytically by three different approaches. Afterward, a singularity analysis is presented based on the Jacobian matrices derived from the kinematic model. The mathematical conditions for singularities are obtained and their geometric interpretation is given. Finally, the workspace of the robot is analyzed and is shown to correspond to a portion of a torus. The analysis reveals that the robot can have a singularity-free workspace of significant size relative to its footprint provided that some simple limitations are introduced at the design stage.
Correlated Pressure–Velocity Instability in a Transonic High-Pressure Turbine Blade
Authors: Dellacasagrande Matteo , Lengani Davide , Bertolini Ettore , Sanz Wolfgang
Published: October 2022

The present work describes the coupled pressure–velocity instability in the suction side boundary layer of a transonic high-pressure turbine blade. The application case is the VKI LS89 turbine blade MUR237. Modal decomposition techniques such as the proper orthogonal decomposition (POD) and the dynamic mode decomposition (DMD) are applied to data obtained by large eddy simulations (LES) to inspect the existing correlation between pressure fluctuations induced by traveling pressure waves and the velocity disturbances growing into the boundary layer. To this end, POD and DMD were applied to both velocity and pressure fields from the leading edge up to the end of the blade surface. DMD was computed on a 2D slice oriented parallel to the blade surface inside the boundary layer. Data were ordered along the curvilinear abscissas, so that the most spatially amplified waves were obtained. Interestingly, unstable velocity modes were detected in the front blade suction side where pressure waves dominate. The unstable velocity modes computed upstream of the peak suction highlighted the occurrence of elongated streaky structures showing spanwise fluctuations which are typical of their instability. The comparison of pressure and velocity modes highlighted the occurrence of pressure-related fluctuations in the velocity field at the same time instants at which streak instability is observed. The analysis carried out in this work suggests that pressure waves can provoke localized instability of boundary layer streaks, which then break up further downstream causing transition.
Validation of Time Domain Seakeeping Computations Based on Capsizing Model Tests in Natural Seaways
Authors: Römhild Wiebke , Russell Philipp , Frühling Christian , Krüger Stefan
Published: October 2022

This paper presents further validation of the numerical computation method E4ROLLS, a nonlinear potential flow theory based seakeeping code, which is especially suitable for the early design stage due to its fast and efficient computation. The validation is achieved by comparison of simulation results with historical capsizing model test results of free-running self-propelled ship models in natural seaways. The results show that E4ROLLS is well-suited to assess the ships’ capsizing vulnerability, especially in following seas. Analysis of the historical tests’ video footage shows that the models’ capsizing in head seas was mainly induced by gusty wind. E4ROLLS is extended to include heeling moments caused by changing wind speeds and directions, so that wind-induced capsizing behavior can also be anticipated. The presented work highlights the benefits of model-scale seakeeping tests in natural seaways and shows that it is possible to assess the seakeeping of ships with fast and reliable methods in the early design stage.
Unsupervised Machine Learning: A Well Planning Tool for the Future
Authors: Batruny Peter , Robinson Tim
Published: October 2022

In recent years, the industry has sought insights from abundant data generated by drilling operations. One of the key focus areas is the rate of penetration (ROP) which impacts costs directly, and emissions indirectly. Previous work has succeeded in predicting and optimizing ROP, however was limited to specific fields and small-scale applications. This limitation stems from unobserved information between different fields or operations that often impacts model usability. This paper provides a new way of well planning by leveraging the power of unsupervised machine learning to deliver higher drilling efficiency, lower costs, and less uncertainty.

Unsupervised machine learning techniques are used to infer information about drilling operations from real-time data that is not directly measured. Certain well types seem to be separable in low dimensions, based on qualitative interpretation of clusters visualized in 2D, and according to analyzing cluster membership based on which wells the data came from, and by associating common characteristics of wells within clusters using external information.

This work introduces a novel approach to collect, separate, and extract value from data that is otherwise unused. Data synthesized by Variational Autoencoders could be used for enhanced well planning, sold as a standalone product, or shared between industry players with reduced privacy concerns, increasing the wealth of data available.
Application of Machine Learning Algorithms for Predicting Added Resistance in Arbitrary Wave Headings of a Ship
Authors: Kim Young-Rong , Steen Sverre
Published: October 2022

Vessels experience additional resistance by waves during navigation, which becomes a factor that increases energy consumption and exhaust gas emissions. Proper estimation and understanding of this additional resistance is an important task in the marine industry. In this study, we propose a machine-learning model that predicts added resistance in arbitrary wave headings using basic ship parameters. First, extensive model experimental data on added resistance for different ship types and sizes of ships were acquired. To build a proper machine learning model, algorithms such as extreme gradient boosting (XGB), random forest (RF), artificial neural network (ANN), k-nearest neighbor (ANN), gaussian process regression (GPR), and support vector regression (SVR) were considered. Through nested cross-validation, the evaluation and hyperparameter tuning of algorithms were performed together. As a result, SVR was selected among the candidate models due to high accuracy with robustness to the outliers. In the validation with test data of head waves and all wave headings, the R2 scores of the selected model were 0.6738–0.7584 and 0.6744–0.7449, respectively, which was better than estimation methods for added resistance in head waves such as STAWAVE-2 and Cepowski (2020), and similar accuracy to those applicable in arbitrary wave headings. Even estimation of added resistance in irregular waves of sea states, the relative deviation with the semi-empirical methods for arbitrary waves was not large, on average 10%.
Modeling and Algorithm Development for Well Trajectory Plan and Real-Time Trajectory Control
Authors: Saavedra Jerez Luis , Sui Dan
Published: October 2022

Drilling automation has become one of the principal goals that the drilling industry is working to achieve in the following years. Particularly the analysis of the trajectory control in realtime is a challenging topic where a simulator can be handy. Our study has developed the Rotary Steerable System (RSS) Simulator, where the drilling calculations, including bit force, bit position, trajectory control under uncertainty, and path corrections, are handled without any human interaction. The in-house RSS Simulator, developed in Python, is based on two general functions: the Trajectory Control Optimizer (TCO) and the RSS model. The TCO builds a planned and optimized trajectory (low dogleg severity and short length), controls the bit’s location, and corrects the trajectory if it has deviated from the plan. The RSS model simulates the bit’s behavior and displacement following the three-axial rate of penetration (ROP) model developed by the University of Stavanger (UiS).

The RSS Simulator has been tested using one well from the Industry Steering Committee on Wellbore Survey Accuracy (ISCWSA) examples. The simulation results show that the proposed trajectory control algorithm can correct and steer, automatically and optimally, the bit direction. The simulations show the importance of the automated deviation control of the simulator in reaching the final target as close as possible.

Finally, implementing the RSS Simulator methods could represent a novel approach within the automation control area that would benefit the drilling industry.
Optimization and Design of Separate Layer Fracturing in Tight Low Permeability Sandstone Gas Reservoir: An Case Study
Authors: Zhang Lufeng , Li Fengxia , Wang Haibo , Wang Jie
Published: October 2022

Tight sandstone reservoirs, widely distributed in the Sichuan Basin of China, are the significant gas exploration and exploitation area and have a profitable development prospect. Separate layer fracturing of vertical well is an indispensable technology to unlock the production potential and enable commercial productivity for tight reservoirs. This paper takes well X located in Zhongjiang County as an example to carry out separate layer fracturing design, aiming to provide an insight for efficient development of tight sandstone reservoirs. The results of laboratory experiments mainly achieved the following findings: 1. The average porosity and permeability of target formation are 4.6% and 0.2 mD. 2. Bedding fractures are locally developed, while overall structural fractures are underdeveloped. 3. The main mineral components are quartz, rock debris, a small amount of feldspar and carbonate cement. 4. Poisson’s ratio and Young’s modulus are 0.18 and 23 GPa, respectively. Moreover, the log interpretation analysis shows that the classification of geological and engineering sweet spots are III and II, respectively. The calculated breakdown pressure is mainly distributed at 107–120 mPa. Furthermore, numerical simulation shows that temporary plugging fracturing technology can achieve the uniform propagation of fractures in segment. The post-fracturing production of well X reaches 50,000 m3/d, marking a breakthrough in exploration for tight sandstone of Xujiahe Formation.
Offshore Energy Hubs in the Decarbonisation of the Norwegian Continental Shelf
Authors: Zhang Hongyu , Tomasgard Asgeir , Knudsen Brage Rugstad , Grossmann Ignacio E.
Published: October 2022

This paper studies the investment planning of a decarbonised Norwegian continental shelf energy system considering the connection and interfaces with the European energy system. A multi-horizon stochastic mixed-integer linear programming model is developed for such a problem. We consider short-term uncertainties, including wind and solar capacity factors, energy load, platform production profiles, and hydro power production limits. Hydrogen based energy hubs are considered both onshore and offshore for potential renewable power generation, distribution and storage. Future hydrogen market or demand is not included in the model. The results of multi-period planning towards 2050 show that: (a) offshore energy hubs are essentially wind power generation, conversion and distribution hubs, (b) a combination of offshore wind and power from shore may be a cost-efficient pathway for cutting emissions from the Norwegian continental shelf, (c) a total of 1.6 GW offshore wind may be needed to achieve a near zero emission Norwegian continental shelf energy system, 80% of which may be added in the first investment period and (d) offshore grid design is important for decarbonisation by distributing wind power efficiently; all five offshore platform clusters are connected to at least three other clusters by 2040, and they are fully connected by 2050.
Design of the Propulsion System for the Autonomous XLUUV MUM
Authors: Greve Martin , Kurowski Martin , Ritz Sebastian , Golz Matthias , Vijayasarathi Lakshmi Narasiman , Bayazit Nursen , Rentzow Erik
Published: October 2022

The paper reports on one aspect in the design of the extra-large unmanned underwater vehicle (XLUUV) MUM, referring to a large Modifiable Underwater Mothership. The vessel will be highly modular and has unique features, such as hydrogen fuel cell and lithium-ion batteries. Modules can be added and rearranged to fulfill different operations. The envisaged operation scenarios pose a challenge to the design of the propulsion and maneuvering system. Due to the limited power and energy storage, it must be efficient during submerged transit, capable of safe surfaced operation in public sea routes and of dynamic positioning. A design study is presented based on an initial design of two variants. The basic hull forms are compared in terms of required forces and moments for vessel motions. Simulations of hull forces are conducted using Reynolds-averaged Navier-Stokes (RANS) equations and vessel motions are determined with an actuator force model. Different arrangements of propulsors and thrusters are investigated and compared concerning their propulsion efficiency and their agility in translatory and rotary directions. The results are presented as tabulated data and in capability plots. A final design is presented and discussed and a conclusion is presented.
Approach to Simulate Fluid-Structure Interaction of a Ship in 3-Dimensional Numerical Towing Tank
Authors: Yamada Yasuhira , Chong Ma
Published: October 2022

In the present study, in order to investigate structural response of ships against slamming, whipping and springing a new approach to simulate fluid structure interaction (FSI) of a ship in three dimensional numerical towing tank using ICFD (Incompressible computational fluid dynamics) methodology is explored. ICFD is the state of the art methodology to simulate both structure and incompressible fluid using finite element method (FEM) where both fluid and structure are modeled with Lagrange mesh with relatively rapid computation time.

As a case study, slamming impact of bow of a container ship is demonstrated. A numerical simulation of water entry of bow into the water is carried out, and displacement, velocity and acceleration of bow, behavior of surrounding water around bow is investigated. Moreover ongoing project of simulation of an elastic-plastic container ship in regular waves in “numerical towing tank” using a whole container ship model is shortly introduced.
Implementation of a Thorough Treatment of Chain Out-of-Plane (OPB) Bending Fatigue With Chainwheel Interaction
Authors: Jones Justin , Childs Ian
Published: October 2022

The effect of out-of-plane bending (OPB) on the fatigue life of moorings has been the focus of extensive study over the last 15 years. Classification societies now require it to be considered in mooring chain fatigue life calculations.

A fatigue analysis of the mooring for a North Sea FPSO was required to support life extension. This paper describes the development of a procedure for the calculation of the fatigue life of the mooring chain with a thorough treatment of fatigue stresses including out-of-plane bending and interaction with the fairlead chainwheel. To include these effects, an integrated method has been developed.

A nonlinear time-domain simulation of the vessel and mooring system is used to calculate time histories of tension, and declination and azimuth angles relative to the vessel for multiple seastates representing the wave-induced fatigue environment. A detailed finite element model of the vessel’s top chain and chainwheel is used to generate transfer functions between chain tension, azimuth and declination angles relative to the vessel, and Dang Van stress.

The mooring time history output and the stress transfer functions are combined to produce time histories of Dang Van stress at nodes across the chain link surface for each seastate. The resulting nodal stress time histories are rainflow counted. Damage is then calculated and summed across all seastates using Miner’s rule.

The results for the integrated method show good agreement with that for tension-tension using chain S-N curves if OPB is omitted, providing validation of the approach. Including the effect of OPB, the increase in annual chain fatigue damage is equivalent to the application of a stress concentration factor of 1.5. The complex history of the particular vessel, including the effect of two deployments and a chain refresh strategy, results in a slight increase in calculated life of the critical link compared to tension-tension fatigue alone when all effects are included.
Analysis of Wave Fields During Ship Accidents in the North-Western Mediterranean
Authors: Innocenti Alessio , Messeri Gianni , Onorato Miguel , Brandini Carlo
Published: October 2022

The occurrence of extreme waves in real sea conditions and their generation mechanisms are key elements in regional forecasts to improve the safety of navigation, especially in those severe conditions where large ships depart and adapt their routes based only on average wave parameters, as the significant wave height. In the present work we have analyzed a series of accidents occurred in the North-Western Mediterranean Sea to large passengers and cargo ships, involving injured people, damages and partial loss of cargo. We have performed phase-resolving numerical simulations based on the Higher Order Spectral Method (HOS), initialized with WaveWatch III (WWIII) directional wave spectra, to analyze in details the sea conditions during the accidents from a statistical point of view. For each case study we have repeated several 3-dimensional realizations to ensure statistical accuracy, and we have tested also the impact of the atmospherical forcing in the WWIII model as well as the nonlinear source term parametrization. The statistical analysis is based on the evaluation of statistical moments as skewness and kurtosis of the free surface elevation, which are typical indicators of nonlinearities and extreme waves, and on the reconstruction of crests distributions, from space-time analysis. Finally, we have focused the attention on spectral shapes similarities among the different case studies and on its possible effect on rogue waves formation.
Temperature Reduction on LNG Bunkering Ship Structure Under Accidental Cryogenic Gas Release Using CFD Simulation
Authors: Nubli Haris , Sohn Jung Min , Jung Dongho
Published: October 2022

Liquefied Natural Gas (LNG) fuel has been proven to minimize sulfur oxide, nitrogen oxide, and particulate matter emissions. LNG fuel becomes a good option to fulfill an alternative fuel demand in shipping industries. Consequently, LNG bunkering ships have to deploy in order to meet the LNG bunkering infrastructure demand. In the event of an accidental LNG release, the cryogenic exposure causes embrittlement of steel that leads to the ship’s structural failure.

The scope of this work is to establish accidental LNG release scenarios considering the leak and environment-related parameters, to observe the cryogenic flow and gas accumulation on the LNG bunkering ship’s structure. The reservoir pressure, leak size, leak directions, leak positions, and release rates are provided as the leak-related parameter. A wind rose data of Ulsan Port (South Korea) is utilized to determine the wind speed, wind direction, and ambient temperature as the environment-related parameter. The release duration is set in 15 minutes which is the emergency shutdown valve reaction time. Kameleon FireEx (KFX) was employed to execute the LNG release simulation. The grid and iteration convergence tests were presented to ensure the current model’s accuracy. Finally, the thermal footprints of structure and gas accumulation characteristics are discussed in this paper.
Data Driven Digital Twin Applications Towards Green Ship Operations
Authors: Taghavi Mahmood , Perera Lokukaluge Prasad
Published: October 2022

Due to the growing rate of energy consumption and its consequent emissions, the International Maritime Organization (IMO) has devised strict rules for an extensive reduction in Greenhouse Emissions (GHG), which forces the shipping industry to search for more energy-efficient solutions. Therefore, alongside with the Energy Efficiency Design Index (EEDI), improving the energy efficiency of existing ships under the Energy Efficiency Existing Ship Index (EEXI) is of considerable importance. This paper address this issue by proposing a digital twin framework supported by big data analytics for ship performance monitoring. The proposed framework is developed by the respective data sets from a selected vessel. For this purpose, a cluster analysis is implemented using the Gaussian Mixture Models (GMMs) with the Expectation Maximization (EM) algorithm. By this approach, the most frequent operating regions of the engine is detected, the shapes of these frequent operating regions are captured, and the relationships between different navigation and performance parameters of the engine are determined. That will make the basis for a digital twin application in shipping. The main objective of this research study is to develop a digital twin of a marine engine by considering the engine operational conditions that can be utilized toward green ship operations. The contribution of this paper and the outcomes can facilitate the shipping industry to meet the IMO requirements enforced by its regulations.
Analyzing Extreme Sea State Conditions by Time-Series Simulation
Authors: Vanem Erik
Published: October 2022

This paper presents an extreme value analysis on data of significant wave height based on time-series simulation. A method to simulate time series with given marginal distribution and preserving the autocorrelation structure in the data is applied to significant wave height data. Then, extreme value analysis is performed by simulating from the fitted time-series model that preserves both the marginal probability distribution and the autocorrelation. In this way, the effect of serial correlation on the extreme values can be taken into account, without subsampling and de-clustering of the data. The effect of serial correlation on estimating extreme wave conditions have previously been highlighted, and failure to account for this effect will typically lead to an overestimation of extreme conditions. This is demonstrated by this study, that compares extreme value estimates from the simulated times-series model with estimates obtained directly from the marginal distribution assuming that 3-hourly significant wave heights are independent and identically distributed. A dataset of significant wave height provided as part of a second benchmark exercise on environmental extremes that was presented at OMAE 2021, has been analysed.
Conceptual Design of a Prestressed Concrete Spar Floater Supporting a 10 MW Offshore Wind Turbine
Authors: Munbua Wichuda , Hasan Muhammad S. , Malta Edgard B. , Gonçalves Rodolfo T. , Fujiyama Chikako , Maekawa Koichi
Published: October 2022

The Government of Japan implemented a new law to promote offshore wind in 2019. However, more than 90% of the 9,074 TWh of Japanese annual wind generation potential is located in the deep ocean, requiring the development of floating platform technology. This study therefore evaluated a conceptual design for a spar-type concrete floater to support a 10 MW offshore wind turbine using precast segment prestressed concrete. This conceptual design was developed based on the economic advantages of using normal-strength concrete. The preliminary dynamic analysis considered the environmental conditions of the Sea of Japan. The stability and motion analyses considered irregular waves under operational, storm, and centenary conditions at the rated wind speed and cut-out wind speed of the wind turbine, as well as typhoon conditions. The geometry of the spar was determined using a coupled dynamic analysis to satisfy hydrostatic and hydrodynamic stabilities. A cross-spectral analysis of the rigid body was then performed to investigate the response motions of the proposed model under the input wind and wave conditions. The results show that the highest force occurred under the rated wind speed in storm conditions, serving as the dominant case for the investigated stress and strain distributions; although the typhoon conditions exhibited higher wind speeds, they corresponded to a relatively small thrust force owing to the action of the wind turbine control system. The concrete compressive stress was close to its compressive strength, with some parts exceeding the limit; thus, the use of high-strength concrete is preferable in future designs. This study thus successfully demonstrated an alternative concrete-to-steel floating spar, addressing the need for future mass production.
A Dynamical System for the Combined Performance of Innovative Biomimetic Thruster With Standard Propulsion System in Waves
Authors: Belibassakis Kostas A. , Filippas Evangelos S.
Published: October 2022

Dynamic wings located at the bow of the ship are investigated for wave energy extraction from ship motions, augmenting ship propulsion in waves and improving dynamic stability in waves. In the context of Seatech H2020 project (https://seatech2020.eu/) flapping-foil thrusters and Dual Fuel engine technologies are combined to provide a renewable-energy-based hybrid solution for the reduction of fuel consumption and operational cost. At first stage of analysis a simplified approximation is developed exploiting data from systematic series for modelling ship propulsion in waves including ship motions and foil loads. In the present work a novel dynamical system is developed and applied to the combined performance of innovative biomimetic thruster in waves. The proposed method exploits seakeeping analysis and unsteady foil theory for the estimation of the ship-foil dynamic system coefficients and loads. The ship steadily advances in the presence of waves that are modelled by parametric spectra corresponding to specific sea states. Appropriate time integration techniques are used for the evolution of the system responses and foil loads. To examine the feasibility of the proposed propulsion innovation in short-sea shipping industry the case of a ferry ship is examined. Numerical results indicate that significant ship performance can be obtained under realistic operating conditions. Thus, the present method can serve as a useful tool for assessment and the preliminary design of such systems extracting energy from sea waves for the augmentation of ship propulsion.
Viscoplastic Fluid Placements in a Confined Geometry With Applications in the Dump Bailing Method in the Plug and Abandonment of Oil and Gas Wells
Authors: Akbari Soheil , Taghavi Seyed Mohammad
Published: October 2022

The plug and abandonment (P&A) operations of oil and gas wells are conducted by placing cement plugs at crucial positions, to preserve the atmosphere and underground water aquifers from the oil and gas migrations. The cement plug should be placed in the wellbore with minimum mixing with the in-place fluid. There are several methods of the cement placement in P&A operations, among which the dump bailing method is one of the most common ones. In this technique, a relatively small amount of cement slurry is released on a bridge plug inside the well and it replaces the in-place wellbore fluids. The dynamics of such a fluid placement is governed by several parameters. In this study, the influence of the yield stress of the injected viscoplastic fluid is analyzed. To do so, the injection of a viscoplastic fluid with low yield stresses into an inclined closed-end pipe (representative of well casing) filled with a light Newtonian fluid is examined. The results show that increasing the yield stress of the injection fluid results in suppressing the mixing between the fluids. The outcomes of this study can be used for enhancing the cementing process in the P&A of the oil and gas wells.
Low Cycle Fatigue in Risers and Pipelines
Authors: Mansour Ghiath (Guy)
Published: October 2022

It is very-well known that fatigue is a primary driver and challenge for steel catenary risers (SCRs) and potentially for steel lazy wave risers (SLWRs) as well. This challenge can be overcome in several ways, some better than others. However, the first step is to predict the fatigue damage properly. Fatigue in risers designed utilizing the working stress design (WSD) method, where stresses are kept below yield, is typically predicted utilizing a stress versus number of cycles to failure (S-N) approach, referred to as high cycle fatigue (HCF). Riser designed utilizing the load and resistance factor design (LRFD), or limit state design (LSD), or strain-based design (SBD) methods are likely to experience yielding and inelastic strains, especially in extreme and survival conditions. Cycles of stresses exceeding yielding and producing inelastic strains occur also in reel-lay operations and are likely to occur in pipelines subjected to large deflections cycles such as over sleepers. Utilizing HCF approach to predict fatigue in this case is inappropriate and a strain versus number of cycles to failure (ε-2N) approach, referred to as low cycle fatigue (LCF), is typically utilized. A detailed approach to predict the LCF fatigue is presented herein along with examples.