bluuebunny/crossref_metadata_2025 huggingface dataset:
Recent climate change strongly impacted the population dynamic of a North American insect pest species
Authors: Boulanger Yan , Desaint Adèle , Martel Véronique , Marchand Maryse , Massoda Tonye Salomon , Saint-Amant Rémi , Régnière Jacques
Published: August 2024

Climate change is redefining the dynamics of forest ecosystems globally, particularly through its impact on forest pest populations such as the spruce budworm (SBW,Choristoneura fumiferana[Clem.]), a major defoliator in North American boreal forests. This study investigates the shifts in the population dynamics of spruce budworm across its range in response to recent climate change. We used a process-based, temperature-dependent ecophysiological model combined with the ERA5 reanalysis to assess changes in SBW phenology, reproduction rate, winter survival and population growth rates from 1950 to 2022 across North America. Our findings demonstrate a pronounced northward expansion of suitable climate conditions for SBW, accompanied by earlier phenological events and increased reproduction rates in northern regions. Conversely, the southern parts of its range are experiencing increased winter mortality due to warmer temperatures. This study highlights the significant impact of elevated temperatures, particularly during critical developmental windows such as spring and summer, which are pivotal for spruce budworm survival and reproduction. Additionally, our results reveal that the observed shifts in pest dynamics are more strongly driven by climate change than by changes in landscape composition and structure. We estimated that suitable growth rates have shifted northward by over 68 km on average, but this shift reached more than 200 km in the easternmost portions of its range. Climate-induced shift in suitable conditions for SBW underscores the need for adaptive forest management strategies that consider the rapid ecological changes and the potential for increased forest vulnerability due to climatic and biotic stressors. This study provides vital insights that can inform adaptive management ensuring the sustainability of forest ecosystems in the face of ongoing climate change.
Magnetoencephalography dimensionality reduction informed by dynamic brain states
Authors: Cathignol Annie E , Kusch Lionel , Angiolelli Marianna , Troisi Lopez Emahnuel , Polverino Arianna , Romano Antonella , Sorrentino Giuseppe , Jirsa Viktor , Rabuffo Giovanni , Sorrentino Pierpaolo
Published: August 2024

Complex spontaneous brain dynamics mirror the large number of interactions taking place among regions, supporting higher functions. Such complexity is manifested in the inter-regional dependencies among signals derived from different brain areas, as observed utilising neuroimaging techniques, like magnetoencephalography. The dynamics of this data produce numerous subsets of active regions at any moment as they evolve. Notably, converging evidence shows that these states can be understood in terms of transient coordinated events that spread across the brain over multiple spatial and temporal scales. Those can be used as a proxy of the “effectiveness” of the dynamics, as they become stereotyped or disorganised in neurological diseases. However, given the high dimensional nature of the data, representing them has been challenging thus far. Dimensionality reduction techniques are typically deployed to describe complex interdependencies and improve their interpretability. However, many dimensionality reduction techniques lose information about the sequence of configurations that took place. Here, we leverage a newly described algorithm, PHATE (Potential of Heat-diffusion for Affinity-based Transition Embedding), specifically designed to preserve the dynamics of the system in the low-dimensional embedding space. We analysed source-reconstructed resting-state magnetoencephalography from 18 healthy subjects to represent the dynamics of the configuration in low-dimensional space. After reduction with PHATE, unsupervised clustering via K-means is applied to identify distinct clusters. The topography of the states is described, and the dynamics are represented as a transition matrix. All the results have been checked against null models, providing a parsimonious account of the large-scale, fast, aperiodic dynamics during resting-state.
Spatiotemporally Programmed Release of Aptamer Tethered Dual Angiogenic Growth Factors
Authors: Rana Deepti , Rouwkema Jeroen
Published: August 2024

In tissue extracellular matrix (ECM), multiple growth factors (GFs) are sequestered through affinity interactions and released as needed by proteases, establishing spatial morphogen gradients in a time-controlled manner to guide cell behavior. Inspired by these ECM characteristics, we developed an “intelligent” biomaterial platform that spatially controls the combined bioavailability of multiple angiogenic GFs, specifically vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF-BB). Utilizing aptamer affinity interactions and complementary sequences within a GelMA matrix, our platform achieves on-demand, triggered release of individual GFs which can be “programmed” in temporally-controlled, repeatable cycles. The platform features stable incorporation of dual aptamers specific for both GFs, functional aptamer-CS molecular recognition in a 3D microenvironment with long-term stability of at least 15 days at physiological temperature, and spatially localized sequestration of individual GFs. Additionally, the system allows differential amounts of GFs to be released from the same hydrogels at different time-points, mimicking dynamic GF presentation in a 3D matrix similar to the native ECM. This flexible control over individual GF release kinetics opens new possibilities for dynamic GF presentation, with adjustable release profiles to meet the spatiotemporal needs of growing engineered tissue.

Graphical Abstract
Turning a Kv channel into hot and cold receptor by perturbing its electromechanical coupling
Authors: Pinto-Anwandter Bernardo I , Bassetto Carlos A Z , Latorre Ramon , Bezanilla Francisco
Published: August 2024

Voltage-dependent potassium channels (Kv) are extremely sensitive to membrane voltage and play a crucial role in membrane repolarization during action potentials. Kv channels undergo voltage-dependent transitions between closed states before opening. Despite all we have learned using electrophysiological methods and structural studies, we still lack a detailed picture of the energetics of the activation process. We show here that even a single mutation can drastically modify the temperature response of theShakerKv channel. Using rapid cell membrane temperature steps (Tsteps), we explored the effects of temperature on the ILT mutant (V369I, I372L, and S376T) and the I384N mutant. The ILT mutant produces a significant separation between the transitions of the voltage sensor domain (VSD) activation and the I384N uncouples its movement from the opening of the domain (PD). ILT and I384N respond to temperature in drastically different ways. In ILT, temperature facilitates the opening of the channel akin to a “hot” receptor, reflecting the temperature dependence of the voltage sensor’s last transition and facilitating VSD to PD coupling (electromechanical coupling). In I384N, temperature stabilizes the channel closed configuration analogous to a “cold” receptor. Since I384N drastically uncouples the VSD from the pore opening, we reveal the intrinsic temperature dependence of the PD itself. Here, we propose that the electromechanical coupling has either a “loose” or “tight” conformation. In the loose conformation, the movement of the VSD is necessary but not sufficient to efficiently propagate the electromechanical energy to the S6 gate. In the tight conformation the VSD activation is more effectively translated into the opening of the PD. This conformational switch can be tuned by temperature and modifications of the S4 and S4-S5 linker. Our results show that we can modulate the temperature dependence of Kv channels by affecting its electromechanical coupling.
Adaptive immunity to retroelements promotes barrier integrity
Authors: Wells Alexandria C. , Lima-Junior Djalma Souza , Link Verena M. , Smelkinson Margery , Krishnamurthy Siddharth R. , Chi Liang , Segrist Elisha , Rivera Claudia A. , Teijeiro Ana , Bouladoux Nicolas , Belkaid Yasmine
Published: August 2024

Maintenance of tissue integrity is a requirement of host survival. This mandate is of prime importance at barrier sites that are constitutively exposed to the environment. Here, we show that exposure of the skin to non-inflammatory xenobiotics promotes tissue repair; more specifically, mild detergent exposure promotes the reactivation of defined retroelements leading to the induction of retroelement-specific CD8+T cells. These T cell responses are Langerhans cell dependent and establish tissue residency within the skin. Upon injury, retroelement-specific CD8+T cells significantly accelerate wound repair via IL-17A. Collectively, this work demonstrates that tonic environmental exposures and associated adaptive responses to retroelements can be coopted to preemptively set the tissue for maximal resilience to injury.
The harmonized information-technology and organizational performance model (HI-TOP)
Authors: Enstroem Rickard , Singh Kang Parminder , Bhawna Bhawna
Published: August 2024

Purpose

This study introduces the Harmonized Information-Technology and Organizational Performance Model (HI-TOP), which addresses the need for a holistic framework that integrates technology and human dynamics within organizational settings. This approach aims to enhance organizational productivity and employee well-being by aligning technological advancements with human factors in the context of digital transformation.

Design/methodology/approach

Employing a two-phased methodology, the HI-TOP model is developed through a literature review and text mining of industry reports. This approach identifies and integrates critical themes related to ICT integration challenges and opportunities within organizations.

Findings

This research indicates that successful ICT integration requires balancing technological advancements with human-centric considerations, including addressing technostress and promoting skills development. The HI-TOP model’s four components – Workforce Empowerment and Resource Strategy (WERS), Technology-Enhanced Information Architecture (TEIA), Organizational Information Processing Strategy (OIPS) and Knowledge Sharing Platform (KSP) – demonstrate operational and strategic synergy required to achieve enhanced organizational performance and adaptability.

Originality/value

The HI-TOP model contributes to the body of knowledge by providing a structured framework for understanding the interplay between technology and organizational dynamics, with an emphasis on employee well-being and overall organizational performance. Its originality lies in the integrative approach to model development, combining theory with empirical insights from industry data, thus offering actionable guidance for organizations navigating the complexities of digital transformation.
Arsenic adsorption from aqueous solution using graphene oxide-sodium silicate nanocomposite modified by silver nanoparticles: process modeling by response surface methodology (RSM)
Authors: Hassanzadeh Ali , Ghorbani Kalhor Ebrahim , Farhadi Khalil , Abolhasani Jafar
Published: August 2024

Purpose

This study aims to investigate the efficacy of Ag@GO/Na2SiO3 nanocomposite in eliminating As from aqueous solutions. Employing response surface methodology, the research systematically examines the adsorption process.

Design/methodology/approach

Various experimental parameters including sample pH, contact time, As concentration and adsorbent dosage are optimized to enhance the As removal process.

Findings

Under optimized conditions, the initial As concentration, contact time, pH and adsorbent dosage are determined to be 32 ppm, 50 mins, 6.5 and 0.4 grams, respectively. While the projected removal of As stands at 97.6% under these conditions, practical application achieves a 93% removal rate. Pareto analysis identifies the order of significance among factors as follows: adsorbent dosage > contact time > pH > As concentration.

Practical implications

This study highlights the potential Ag@GO/Na2SiO3 as a promising adsorbent for efficiently removing industrial As from aqueous solutions, and it is likely to have a good sufficiency in the filtration of water and wastewater treatment plans to remove some chemical pollution, including paints and heavy metals.

Originality/value

The simplicity of the nanocomposite preparation method without the need for advanced equipment and the cheapness of the raw materials and its potential ability to remove As are the prominent advantages of this research.
Could oxygen gradient ektacytometry help to detect sickle cell trait carriers at risk for kidney disorders or exercise‐related complications?
Authors: Connes Philippe , Nader Elie
Published: August 2024

The study of Ellsworth et al. (Br J Haematol, 2024) demonstrated the usefulness of oxygen gradient ektacytometry technique to better identify the physiological parameters that could increase the risk of sickling of red blood cells (RBCs) from sickle cell trait (SCT) carriers. Oxygen gradient ektacytometry combined with pH and osmolality modulations could help in identifying SCT carriers at risk for kidney disorders or exercise‐related complications. Other factors than the percentages of haemoglobin S are probably involved in the propensity of RBCs from SCT carriers to sickle during deoxygenation.

Commentary on: Ellsworth et al. Hypertonicity and/or acidosis induce marked rheological changes under hypoxic conditions in sickle trait red blood cells. Br J Haematol 2024 (Online ahead of print). doi: 10.1111/bjh.19669.
Cenozoic Ampelopsis and Nekemias leaves (Vitaceae, Ampelopsideae) from Eurasia: Paleobiogeographic and paleoclimatic implications
Authors: Tosal Aixa , Vicente Alba , Denk Thomas
Published: August 2024

We describe a new species of Ampelopsideae (Vitaceae), Nekemias mucronata sp. nov., from the Rupelian of Cervera (Spain) and revise another fossil species, Ampelopsis hibschii, originally described from Germany. Comparison with extant Ampelopsideae suggests that the North American species Nekemias arborea is most similar to Nekemias mucronata while the East Mediterranean Ampelopsis orientalis is the closest living relative of A. hibschii. Our review of fossil data indicates that, during the Eocene, four species of Ampelopsideae occurred in Eurasia, that is, N. mucronata in the Czech Republic, A. hibschii in Kazakhstan, and two fossil species in the Far East (Ampelopsis cercidifolia and Ampelopsis protoheterophylla). In the Oligocene, a new species, Ampelopsis schischkinii, appeared in Kazakhstan; meanwhile, N. mucronata spread eastwards and southwards, and A. hibschii mainly grew in Central Europe. In the late Oligocene, N. mucronata became a relict in the Iberian Peninsula and Nekemias might have persisted in Western Eurasia until the latest Miocene (“Ampelopsis” abkhasica). The last occurrence of A. hibschii was in the Middle Miocene in Bulgaria, probably a refuge of humid temperate taxa, along with Ampelopsis aff. cordata. Carpological remains suggest that this lineage persisted in Europe at least until the Pleistocene. Our data confirm previous notions of the North Atlantic and Bering land bridges being important dispersal routes for Ampelopsideae. However, such dispersion probably occurred during the Paleogene rather than the Neogene, as previously suggested. A single species of Ampelopsideae, A. orientalis, has survived in Western Eurasia, which appears to have been linked to a biome shift.
Street‐level bureaucrats' perceptions of “the job”: Deviation from professional particularities and micro creation of public value
Authors: Lavee Einat , Cohen Galia
Published: August 2024

The implementation work of street‐level bureaucrats (SLBs) is becoming more complex due to concurrent imperatives. While previous research has focused on SLBs' discretion decisions and coping strategies, this study adds to existing literature by suggesting that their perceptions of “the job” are changing. Drawing on in‐depth interviews with 87 US police officers, we found that SLBs are influenced by the great emphasis on public value, understanding their job in terms of assuming general responsibility for citizens, as public representatives. They adopt various strategies to respond to citizens' needs, providing a vast range of services that deviate from their traditional job. We conclude that SLBs work constantly, formally and informally, to effectively address what is good for the public, in ways that go beyond their professional particularities. We argue that such a broader perspective requires public administration scholars to consider more critically the expanded job perceptions, manifested in expanded professional responsibility.
Patient‐reported outcome measures and health economics in regenerative periodontal therapy: A systematic review and meta‐analysis
Authors: Chen Zhaozhao , Lin Cho‐Ying , Wang Hom‐Lay
Published: August 2024

Understanding patient responses to periodontal regeneration is crucial. This systematic review and meta‐analysis addressed two key questions: (a) the impact of periodontal regeneration on patient‐reported outcome measures (PROMs) for intrabony and furcation involvement and (b) the cost‐effectiveness of periodontal regeneration for treating periodontal defects. Twenty‐four studies were included, with 20 randomized clinical trials (RCTs) reporting patient‐reported outcomes and five (three RCTs and two economic model‐based studies) reporting cost‐effectiveness outcomes. Results favored regeneration therapy over conventional flap surgery for intrabony defects, showing improvements in qualitative (i.e., amount of regenerated attachment apparatus) and quantitative parameters (i.e., probing and radiographic parameters). In terms of PROMs, regenerative treatments involving barrier membranes resulted in longer chair times and higher rates of complications (such as membrane exposure or edema) compared to flap with biologic agents or access flap alone. Despite this, oral health‐related quality of life improved after both regenerative and extraction procedures. Economically, regeneration remained favorable compared to extraction and replacement or open flap debridement alone for periodontal defects. Single‐flap variants in open flap debridement yielded similar outcomes to regenerative treatment, offering a potentially cost‐effective option. Nevertheless, further discussion on the benefits of less‐invasive flap designs is needed due to the lack of histological evaluation.
Investigation of the Responses of Drilling Parameters at Various Bit Rock Interactions and the Inter-Relation to Drilling Performance
Authors: Abugharara Abdelsalam N. A. , Alwaar Abourawi , Futheiz Ibrahim , Butt Stephen D.
Published: August 2024

Accurately understanding the recorded signals of the outcome drilling parameters, precisely linking them to the applied parameters under the determined surface and downhole conditions, correctly interpreting them for better visualization of the downhole drilling conditions to optimize the applied drilling parameters assist in achieving the best drilling performance, minimizing the costs, and significantly reducing the Non-Productive Time (NPT). The aim of this research is to analyze the responses of the drilling parameters’ signals under various status of Bit Rock Interactions (BRI) through applying an innovative laboratory technique and methodology. The aim also includes making correlations of the input and the output parameters for better understanding the parameters’ interrelationships under various status of the bit rock interactions generated by a continuance drilling through precored multi-diameter holes. The research methodology involved a comprehensive laboratory drilling tests using a Large-scale laboratory Drilling Simulator (LDS) at the drilling Technology Laboratory (DTL) of Memorial University of Newfoundland (MUN). Two rock types were used for the drilling experiments, which include granite and sandstone with high and medium strength, respectively. The whole process involved two stages. Stage one involved a pre-coring process using different diameters of impregnated coring bits. The purpose of this stage was preparing a multi-diameter hole to be tested through drilling using a 5-cutter Polycrystalline Diamond Compact (PDC) bit during stage two, where the continuance drilling occurs under a constant applied parameter of Weight On Bit (WOB) and a Revolution Per Minute (RPM). Core bits were perfectly aligned by utilizing downhole bushings with bearings for centralization and friction elimination. The applied parameters that were kept constant included WOB, RPM, formation type, and water Flow Rate (FR). The process of data analysis was conducted on the outcome drilling parameters that included torque and signal amplitude of WOB with respect to a corresponding bit rock interaction. Results showed very useful information between the responsive torque and the applied WOB signal amplitude at a constant applied WOB and other input drilling parameters. This research found novel results that show the decrease in the responsive torque when the area of contact and the bit-rock interaction increase at a constant WOB. Typically, the torque increases when the area of contact increases as a sign of more bit rock interaction involved. Research methodology, experimental procedure, data analysis and results are reported.
Numerical Investigation on the Effects of Diffuser Inlet Opening Angles on the Performance of a Drag-Based Hydrokinetic Turbine
Authors: Ng Cheng Yee , Riyaz Nauman Maldar , Ong Muk Chen
Published: August 2024

The potential of ocean energy as a renewable source is widely acknowledged. Ocean currents energy is one of the ocean energies, which is harnessed by using hydrokinetic turbines (HKTs). Despite continuous efforts on the optimization of HKTs’ energy conversion performance, challenges remain in regions with slow flow velocities. This study aims to investigate the effects of incorporating a diffuser into a HKT design on the power output performance. Numerical simulations using the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations and renormalized group (RNG) k-ε turbulence model is conducted by varying the diffuser inlet opening angles (θi = 15°, 20°, 25°, 30°, and 35°). The results show that the highest flow velocity is measured at the diffuser throat for all angles, which a deceleration flow effect is also observed here. This decelerated flow zone is found to be extended from the diffuser wall to its midline. The optimal configuration for power and torque coefficients is found in inlet opening angle of 20°. Overall, incorporating a diffuser with the optimum inlet opening angle in the HKT design improves the power generation efficiency compared to the HKT configurations without a diffuser.
Estimating the Most Likely Extreme Nacelle Acceleration of a Floating Offshore Wind Turbine From Physical Model Tank Testing
Authors: McMillan Ailsa , McDonald Alasdair , Pillai Ajit C. , Yuan Zhiming , Davey Thomas
Published: August 2024

The floating platforms on which floating offshore wind turbines are mounted introduce considerable complexity in terms of dynamic motion. Understanding the extreme response of these marine structures is important. One such extreme response is the nacelle accelerations, which can cause damage to nacelle components, such as the generator, and should therefore be kept to a minimum. Tank testing is a tool which can be used to understand the behaviour of these structures, and to determine extreme response. Here, a method of estimating the most likely extreme nacelle accelerations from a tank testing programme is shown, using a 1:100 scaled model of the IEA 15 MW turbine with the Volturn-US semi-submersible platform. The results showed that the most likely extreme nacelle accelerations within the chosen 50-year return sea state are 0.195 g in the fore-aft direction, with a typical safety limit of 0.2–0.4 g. Extreme statistical analysis was carried out on the data obtained by a 3-DOF accelerometer, using the peaks-over-threshold (POT) method fitted to a generalised Pareto distribution (GPD). Threshold selection and declustering of data are also discussed. The results may be applied to further test programmes, aiding in the development and design of current or novel floating platforms in any programmable sea state.
Bending Stiffness of Unbonded Flexible Pipes and its Application in Installation
Authors: Zhu Linfa , Zhou Yan , Hou Yucheng , Reuter Jason , Yuan Jiabei , Tan Zhimin , Roberts Andrew
Published: August 2024

The bending hysteresis behavior of unbonded flexible pipe is well known and fully implemented in flexible riser system design and analysis, for example, extreme, interference and fatigue analysis. However, in some quasi-static applications, the inclusion of the full bending hysteresis loop sometimes leads to noticeable deviations from configurations observed in the field.

To address the issue, this paper intends to interpret these differences from the nature of the internal friction, which is the main mechanism governing the pipe bending hysteresis behavior. Two operation cases are presented for the study: 1) a flowline installation, and 2) a flexible riser wet storage. The pipes in both cases are not subjected to any significant wave excitations. Therefore they are considered quasi-static applications. The flowline installation involves a camelback configuration at the end fitting-gooseneck connection. The riser wet storage case involves wave configuration with installation ballasts, considering about a 1-year wet parking period. The paper presents a configuration sensitivity study with different bending stiffnesses and identifies the one that produces the best agreement between the predicted and measured configuration in the survey. Based on the findings, the paper also recommends the most appropriate use of pipe bending stiffness in designing quasi-static jumpers, which predicts accurate configuration and associated support interfacing loads thus avoiding excessive conservatism.
Research on Temperature Field Distribution of Helical Carcass Supported Composite Flexible Cryogenic Pipe for LNG
Authors: Bu Yufeng , Yan Jun , Yin Yuanchao , Yang Zhixun , Fu Ying , Hailong Lu
Published: August 2024

Helical carcass supported composite flexible cryogenic pipe (hc-FCP) for LNG is one of the key equipment of floating liquefied natural gas (FLNG) storage and offloading device system. Hc-FCP cross-sectional form is complex, and the operation needs to withstand −163 °C cryogenic, which causes a change in the properties of the material inside the pipe. Therefore, obtaining the temperature field distribution of a pipe structure is essential for predicting its mechanical properties. In this paper, a two-dimensional axisymmetric steady-state heat transfer numerical model of the hc-FCP is constructed, and the accuracy of the numerical model is verified through prototype experiments, and the temperature field distribution at the actual working temperature of the pipe is characterized by a gradient distribution along the radial direction and a corrugated type distribution along the axial direction. The influence law of outside environmental factors on the temperature field distribution characteristics of the pipe is also discussed. The results show that the temperature gradient between the inner and outer surfaces of the pipe increases as the ambient temperature rises; the temperature change between the inner and outer surfaces of the pipe increases as the ambient wind speed increases, and the effect of wind speed on the change of the pipe temperature field becomes smaller and smaller as the wind speed increases.
Numerical Study on Tip-Gap Flow of a Hydrofoil
Authors: Takahashi Kenshiro
Published: August 2024

Ducted propellers are expected to provide significant hydrodynamic and hydracoustic benefits for underwater vehicles. However, ducted propellers typically have a tip gap between the blades and duct surface, which can cause flow instabilities and cavitation resulting in undesirable noise. Therefore, understanding the tip-gap flow mechanism is critical for managing the hydroacoustics of these propulsors. This study focused on a fundamental analysis of a tip-gap flow of a hydrofoil using computational fluid dynamics. The Reynolds-averaged Navier-Stokes (RANS) turbulence model was primarily used to compute the mean global features of the tip-gap vortices, whereas a large-eddy simulation (LES) was used to resolve the crucial turbulent structures. A mesh refinement study was performed by decreasing the mesh size in the tip-gap region. The computed vortex topology in the tip-gap region was similar to that obtained in an experiment. Further analysis of the tip-gap flow was conducted, and several remarks are discussed regarding the formations of tip-separation vortex, tip-leakage vortex, and induced vortex yielded. The LES computed the complex vortex structures, and the result was compared with that obtained with the RANS simulation.
Parametric Study on Tip-Gap Flow of a Hydrofoil Using Computational Fluid Dynamics
Authors: Takahashi Kenshiro
Published: August 2024

Ducted propellers are expected to provide significant hydrodynamic and hydroacoustic benefits for underwater vehicles. However, ducted propellers typically have a tip gap between the blades and duct surface, which can cause flow instabilities and cavitation, resulting in undesirable noise. Therefore, understanding the tip-gap flow mechanism is critical for managing the hydroacoustics of these propulsors. In this work, a parametric study on the tip-gap flow of a hydrofoil was performed using computational fluid dynamics. The tip-gap height, incident angle, Reynolds number, and section profile were the investigated parameters. The extensions of the tip-leakage vortex (TLV) and tip-separation vortex (TSV) decreased for smaller tip-gap heights. The isosurface of vapour pressure in the TLV was not observed for the largest tip-gap height, whereas it remained near the leading edge for the smallest tip-gap height. The TSV and TLV were mitigated for smaller incident angles, although a lower pressure region was yielded at the leading edge even for no incident angle. The global features of the TLV and TSV were similar for different Reynolds numbers. However, a greater leakage flow was observed for a higher Reynolds number. Enlarged TLVs and expanded lower pressure regions were observed for the thinner and cambered hydrofoils.
Impact of Roll Waves in Mudflow on Hydraulic Structures
Authors: Yu Boyuan , Chu Vincent H.
Published: August 2024

Mudflow is destructive because the flow’s tendency to become unstable at a small Froude number, leading to roll waves of a steep front that can strike an obstacle with great force. We conducted simulations of roll waves in mudflow down an inclined open channel to determine the impact force of the waves against hydraulic structures of various shapes and orientations using a depth-averaged shallow-mudflow model. The roll waves increase in amplitude with distance from a local disturbance. The rate of the increase depends on the Froude number of the undisturbed flow, and the rheological properties of the mud. The wave-impact force could reach a peak of more than an order of magnitude greater than the force on the structure without the roll waves. However, an obstacle with a sharp and pointy front can deflect the incident waves, significantly reducing the impact force.
A Sensitivity Analysis of the Voyage Adjustment for Sailing in Ice of the Carbon Intensity Indicator Regulation
Authors: Tran Trung Tien , Browne Thomas , Veitch Brian
Published: August 2024

The Carbon Intensity Indicator (CII) regulation came into force in 2023 with the objective of reducing greenhouse gas emissions in the maritime industry. Ice-classed vessels sailing in ice have been granted a voyage adjustment in the CII regulation. The voyage adjustment allows ice-classed vessels to exclude from the calculation of CII the part of any voyage that constitutes sailing in ice. The current study examines a sensitivity analysis of definitions for sailing in ice conditions. Sailing in ice is defined in the current regulation as an ice-classed vessel operating in a sea area within the ice edge. Alternative definitions have been considered which are more specific in terms of concentration and thickness of the ice field where the vessel operates. We present a case study of a conventional diesel-powered bulk carrier with ice class IA Super on a voyage in the Canadian Arctic. Routing of the vessel is optimized based on an assumed rewards function, a routing algorithm, and a ship performance model. We compare the routes selected under different definitions of “sailing in ice conditions”. The results show that different definitions of sailing in ice conditions lead to different optimal routes for the vessel, some of which are more effective than others in meeting the IMO’s strategic objective of reducing emissions.
The Influence of Current Profile on On-Bottom Stability of Subsea Cable
Authors: Hao Mingxuan , Longva Vegard , Ye Naiquan , Ji Guomin , Sævik Svein
Published: August 2024

With the development of offshore wind industry towards deeper water depth, the demands for transferring electricity through subsea power cables over long distance across uneven seabed have increased. An important design criterion in subsea cables is to ensure that the cable can remain stable on the seabed when exposed to complex hydrodynamic loads induced by waves and currents. Accurate current profile is critical in assessing the hydrodynamic loads property on the cable. The current profile near seabed is significantly affected by the boundary layer effect above the sea bottom. According to common practice, the boundary layer related to the wave kinematics at the seabed, is usually neglected. This is known to have a marginal effect for large diameter subsea pipelines. However, the diameter of the subsea cable may be in the same order as the boundary layer thickness and its impact on the on-bottom stability can therefore not be ignored.

DNV-RP-F109 includes the ability to take the effect from waves onto the current profile into account. In the present study, time-domain dynamic on-bottom stability analysis of a subsea cable is performed by using a tailor-made finite element program SIMLA to investigate the influence of the boundary layer. The case study is conducted on a 300-mm-diameter cable, which is placed on a sandy soil in shallow water, exposed to irregular waves and two different current profiles, however, by respectively excluding and including the wave effect on the current profile. Sensitivity study regarding different diameter and submerged weight of soil has been carried out and validated against published paper.
Conceptual Design of a Hybrid Floating Offshore Wind Turbine Integrated With Hydrogen Production and Storage System
Authors: Pham Thanh Dam , Trinh Luan Cong , Dinh Van Nguyen , Leahy Paul
Published: August 2024

The shift towards renewable energy requires sustainable energy carriers, with hydrogen emerging as a crucial player in creating a lasting and stable decarbonized energy sector. Floating offshore wind turbines are expected to become a major contributor to renewable electricity because they can harness wind energy over a vast area of the ocean, areas which fixed-bottom wind turbines cannot reach. Combining floating offshore wind turbines with hydrogen production and storage potentially creates a powerful solution to address the variability of wind energy and allows the production of zero-carbon “green” hydrogen from wholly renewable sources. Additionally, integrating hydrogen systems with large floating offshore wind turbines allows for decentralized and easily-scalable energy production and storage. This approach not only boosts energy security in coastal and island states but also reduces dependence on existing energy networks.

This paper introduces a conceptual design of a hybrid system. It integrates a 15 MW semi-submersible floating offshore wind turbine with a hydrogen production and storage unit, both mounted on the same semi-submersible floating platform. The system mass properties are modeled in Catia, and its dynamic behaviors are analyzed using the OpenFAST software. Essential tests performed include free decay tests and response amplitude operator analysis to observe the platform’s movements. The primary goal is to verify the system stability during different operational events and varying environmental factors. The analysis emphasizes the advantages and potential of combining offshore wind turbine technology with hydrogen storage and production systems.
A Novel Approach for Assessing the Accuracy of Prediction Models
Authors: Wang Hexian , Guo Lingyun
Published: August 2024

Currently, prediction models universally contend with model errors and lack a method for assessing their accuracy. Based on statistics, this paper proposes a novel approach that involves estimating the feature parameters of the database, determining the best-fit distribution and calculating the recommendation factor. Based on this approach, we developed an intelligent characterization extraction machine (ICEM) containing three processors: the Feature Parameter Extractor (FPE), the Fitted Distribution Processor (FDP), and the Recommendation Factor Processor (RFP). Firstly, a detailed database consisting of prediction accuracy needs to be inputted into ICEM; secondly, the FPE estimates the characteristic parameters of the database, and the FDP determines the best-fit distribution; finally, the RFP will give the recommendation factor. In this paper, an example is designed to show the ICEM’s application in evaluating the prediction accuracy of failure assessment model for pipes with axial cracks on the outer surface. The results show that: the software can compute the characteristic parameters and determine the best-fit distribution of the database which can quantify predicted performance and provide recommended safety factors.
Experimental Modelling of Wave-Structure-Soil Interaction of a Floating Offshore Wind Turbine at Large Scale
Authors: Windt Christian , Goseberg Nils , Schimmels Stefan , Kudella Matthias , Shanmugasundaram Ranjith , Rusche Henrik , Sumer B. Mutlu , Kirca V. S. Özgür , Yilmaz S. Utku , Vanjakula Vinay , Adam Frank , Smyczynski Marcin , Kazimierowicz-Frankowska Krystyna
Published: August 2024

The understanding of the wave-structure-soil interaction around marine structures is important in order to drive design decisions towards lean, yet resilient marine infrastructure. In particular, in the light of the increasing use of the marine environment for renewable energy generation, analysis of the wave-structure-soil interaction becomes increasingly relevant. While most experimental studies on wave-structure-soil interaction are conducted at small to medium scale, this paper presents the initial results of an experimental test campaign on the wave-structure-soil interaction of a floating offshore wind turbine at large scale. The data of the period averaged pore pressure reveal a significant buildup of pore pressure beyond the onset of liquefaction, which can be attributed to the additional structural loading when comparing results to similar, isolated wave-soil interaction cases in the absence of a structure.
Evaluating Position Control for Real-Time Hydrodynamic Motion Response in a Robotized Dry Test Rig With a Point-Absorber WEC
Authors: Salar Dana , Hultman Erik
Published: August 2024

A robotized dry test rig in six degrees of freedom, for emulating the influence of hydrodynamic forces on and the resulting motion response of different types of point absorbing wave energy converters has been developed at Uppsala University. In the past we have investigated and shown that the dry test rig works with both force and position control methods.

In this article we further examine the position control method, as we have not been able to use it for rougher wave movements. This is due to the fact that there has been a control lag in the system which contributed to the system becoming unbalanced in some emulation scenarios. A solution for an updated position control method, with significantly reduced control lag, is demonstrated in robot simulations and compared with both hydrodynamic model simulations and physical robot experiments for two buoy sizes in regular waves.

The results show a clear positive solution for avoiding control lag problems, making the position control method fully possible to use in the field. Future work is to implement the updated method on the physical robot test rig.
AI-Based Surrogate Model for the Prediction of Ship Fuel Consumption Reflecting Hydrometeorological Conditions
Authors: Zhang Mingyang , Tsoulakos Nikolaos , Kujala Pentti , Hirdaris Spyros
Published: August 2024

Accurate prediction of ship fuel consumption is essential for optimizing ship performance and minimizing environmental impact. This study presents the development and validation of an artificial intelligence (AI)-based surrogate model specifically designed to predict Ship Fuel Consumption (SFC) in the case of a bulk carrier. The surrogate model employs a cutting-edge approach by combining deep learning techniques, specifically incorporating attention mechanisms into Bidirectional Long Short-Term Memory (Bi-LSTM) networks. This advanced model leverages a rich and diverse dataset comprising crucial operational parameters, including ship navigation, ship operational conditions, engine operational status, and Metocean data, to achieve highly accurate predictions of SFC. The dataset used for training and validation is sourced directly from realistic bulk carrier operations, ensuring the relevance and practical applicability of the model. Extensive generalization tests were conducted to evaluate the performance of the developed surrogate model. The results indicate that the AI-based surrogate model achieves long-term high accuracy in predicting ship fuel consumption under varying operational conditions. The developed surrogate model may serve as a valuable tool for bulk carrier operators, offering insights into fuel efficiency improvements and enhancing the overall sustainability of ship operations.
Experimental Research of Innovative Composite Offshore Structure for Umbilicals Transportation and Installation
Authors: Atutis Mantas
Published: August 2024

Sustainable design and manufacturing of low-carbon structures is a major concern for the offshore renewables industry. Fiber reinforced polymer (FRP) composite materials are seen as a suitable alternative to traditional structural materials due to their high strength and light weight. Due to the high potential of offshore windfarms and high expectations from the industry mentioned benefits provide significant savings in subsea and offshore applications of FRP composite materials. Safety, structural integrity, and corrosion resistance are essential factors to consider aggressive offshore and subsea environments. Current research presents a comparative experimental investigation and introduces a new type of composite structure considering glass fiber reinforced polymers (GRP) in lieu of conventional carbon steel for umbilical or cable storage, sea transportation and subsea installation. Due to lack of standard and experimental results, a new prototype is experimentally tested on site based on large scale experimental program. Identified priorities reflected to this research work by promising application of GRP composite material may find innovative use in offshore environment.
Experimental Study of Shielding Effects of Aluminum Alloy Net Panel in Waves
Authors: Lei Yu , Zheng Xiang Yuan , Liu Xin , Yan Shu , Cai Xiao , Zhang Sheng
Published: August 2024

For the traditional polyethylene and nylon nets, lots of studies have been carried out to study their hydrodynamic characteristics in waves and currents. However, the studies of the metal nets which also have wide application prospect in marine aquaculture are rare, especially on their performance in waves. In this study, a series of laboratory experiments are conducted to investigate the hydrodynamic characteristics of the chain-link type aluminum alloy nets. Two net panels of identical dimensions are placed in the ocean basin. They are parallel to each other, with a certain length of gap. The wave forces on the net panels under different wave heights, wave periods and immersion depths are measured. The wave elevations at different downstream positions of the nets and the wave forces on both upstream and downstream net panels are measured to investigate the shielding effects. The wave transmission coefficient and shielding coefficient of the horizontal wave force are therefore derived. The experimental results show that both two coefficients are around 1 under different wave conditions which indicates that the shielding effects of the chain-link type aluminum alloy nets can be ignored. Thereby, in the calculation of wave loads on upstream and downstream fish nets, it is reasonable to neglect the wave attenuation inside the nets.
Volumetric Design for Hydrodynamic Response of Modularized Lightweight TLP Structures Under Irregular Waves
Authors: Abbasnia Arash , Kosleck Sascha , Buhr Eric , Lutz Marco , Adam Frank
Published: August 2024

The increasing demand for developing offshore renewable power plants sparks a search for designing floating units that can effectively support energy conversion systems in terms of power storage and transfer, whilst being located far from the shore. The modularized floating structures initiative is highly valued for its ability to easily adjust its operational range to match the capacity of variable energy systems by adding or removing structural members. The circular cross-section’s superior resilience against fatigue and hydrodynamic pressure, as compared to other cross-sections, has prompted an investigation of a tension leg platform modularized by cylindrical members as presented in this paper. The study focuses on a hydrodynamic assessment under various wave conditions. Consequently, a range of centre of buoyancy and volume moments of inertia is triggered by different module sizes and arrangements for a constant displacement. Amongst the numerous possible variations, three module arrangements are subjected to JONSWAP wave spectra. The mooring system assumes linear stiffness with four single-string tendons in the perpendicular configuration. The study employs a linear potential model to calculate the structure’s hydrodynamic responses. The comparison of results illustrates the significant impact of volumetric characteristics on the structure’s operation. Hydrodynamic coefficients, kinematics of the structure and tension loads are scrutinized and comprehensively compared.