bluuebunny/crossref_metadata_2025 huggingface dataset:
On space–time diversity in shock train self-excited oscillation mode during wide-range evolution in a scramjet isolator
Authors: Ji Yuan , He Miaosheng , Huang Xiaobin , Sheng Haoqiang , Wang Wei , Xie Mingyun , Liu Hong
Published: November 2024

The shock train self-excited oscillation can induce combustor instabilities and reduce engine margin. In a dual-mode scramjet, the shock train undergoes a complete evolution process, exhibiting structural changes closely tied to this inherent unsteadiness. This study aims to elucidate the space–time diversity in shock train self-excited oscillation mode and the underlying mechanisms during wide-range evolution. The experimental investigations were conducted at Ma = 1.95, capturing the complete evolution of the shock train. The results indicate the evolution can be categorized into three regimes based on structural characteristics. In regime I, the shock region gradually forms, followed by the occurrence of the mixing region in regime II. Regime III corresponds to inlet unstart. In regime II, isolator outlet pressure fluctuations exhibit higher frequency and lower amplitude compared to regime I, while the shock motion demonstrates lower frequency and higher amplitude. The shock train behaves in a large-scale, low-frequency (1.53 times the duct height, 10 Hz) unsteady motion in regime II, posing a potential threat to engine operation. Coherence and phase analysis reveal the disturbance source originates downstream. Proper orthogonal decomposition modal analysis shows two oscillation modes: low-frequency components correspond to shock motion, and high-frequency components correspond to pressure fluctuations across the entire pseudoshock. The propagating of downstream disturbance differs between the two regimes. In regime I, the shock train exhibits rigid-body motion synchronously. In regime II, the relative motion between each shock wave and the cumulative effect of pressure disturbance lead to frequency decay upstream, amplifying the shock train motion.
Boosting the two-dimensional electron gas density of Al0.20Ga0.80N/GaN heterostructures by regrowth of an epitaxial Sc0.18Al0.82N layer
Authors: Yin Yuhao , Zhao Haiyang , Liu Rong , Fan Shizhao , Sun Jiandong , Qin Hua , Song Helun , Li Jiadong , Dong Shitao , Sun Qian , Yang Hui
Published: November 2024

Sc-alloyed AlN epilayers were grown on commercial GaN/sapphire templates by molecular beam epitaxy (MBE) to validate the Sc composition of 18% and in-plane lattice matching with GaN. As-grown Sc0.18Al0.82N/GaN heterostructure exhibits a two-dimensional electron gas (2DEG) density of 3.58 × 1013 (2.96 × 1013) cm−2 and a mobility of 241 (295) cm2⋅V−1⋅s−1 at 300 (77) K, demonstrating the feasibility of employing its high spontaneous polarization toward high 2DEG density and highlighting detrimental impurity scattering due to the regrowth interface. Implementation of AlN impurity blocking layers boosts 2DEG mobility to 1290 (8730) cm2 V−1⋅s−1at 300 (77) K. In addition, we have engineered a surface-treatment strategy to selectively decompose the 2.5-nm-thick GaN cap layer of commercial GaN(2.5 nm)/Al0.20Ga0.80N(22 nm)/GaN heterostructure epi-wafers at high temperature prior to MBE regrowth of Sc0.18Al0.82N to eliminate impurity incorporation at the regrowth interface. Regrowth of a Sc0.18Al0.82N layer on the pristine Al0.20Ga0.80N surface increases 2DEG density from 7.89 × 1012 to 9.57 × 1012 cm−2, together with a slight reduction in mobility from 2160 to 1970 cm2⋅V−1⋅s−1 at 300 K, reducing the sheet resistance by 10%. Our calculation implies that it is practical to boost 2DEG density to over 2.0 × 1013 cm−2 by thinning Al0.20Ga0.80N down to 4 nm.
Non-Gaussian properties and their effects on extreme wind pressure of a 4:1 rectangular cylinder
Authors: Liu Xiaobing , Ruan Lijun , Jiang Huimin , Chen Anjie , Yang Qun
Published: November 2024

This paper investigates the wind pressure characteristics of a 4:1 rectangular cylinder under 19 wind angles using a rigid model wind tunnel test, focusing on non-Gaussian properties and extreme wind pressure. The wind angle (α) varies from 0° to 90° and the Reynolds number (Re) ranges from 0.32 × 105 to 2.14 × 105. The spatial and statistical distributions of wind pressure, along with its non-Gaussian properties, are presented. Detailed analyses of these characteristics are provided. The peak factor of wind pressure was calculated using the modified Hermite method. The results indicate that the skewness and kurtosis of the windward region of the 4:1 rectangular cylinder remain relatively unchanged with varying wind angles. In contrast, the skewness and kurtosis in the separation and wake zones are significantly influenced by changes in the wind angle. Most wind pressures on the 4:1 rectangular cylinder exhibit negative bias and a softening process. The non-Gaussian properties are most prominent at the corner of the wake zone. The peak factor of 2.5 (used in Chinese code) or peak factor g,G based on Gaussian processes on the separation and wake zones of interest are much smaller than the peak factors g,NG calculated based on the modified Hermite method. Ignoring non-Gaussian properties underestimates extreme wind pressures by at least 20%–30%. Therefore, non-Gaussian properties must be considered when calculating wind pressure extremes for similar rectangular structures. Additionally, the peak factor value in the Chinese code should be increased appropriately to ensure structural safety.
A novel generative approach to the parametric design and multi-objective optimization of horizontal axis tidal turbines
Authors: Xia Tianshun , Wang Longyan , Xu Jian , Yuan Jianping , Fu Yanxia , Luo Zhaohui , Wang Zilu
Published: November 2024

As the demand for ocean energy continues to grow, the development of efficient design and optimization methods for tidal current turbines is crucial. Traditional approaches, often based on parameterized models, face challenges in fully capturing the intricate geometric features of turbine blades, limiting the optimization space and affecting convergence efficiency. In response, this study introduces a novel design methodology for horizontal axis tidal turbines (HATTs) using a variational autoencoder generative adversarial network (VAEGAN) model. This approach uses unsupervised learning from a custom dataset to generate new HATT designs, with the VAEGAN model encoding distinct geometric features of turbine blades within a compact latent space, enabling more efficient design space exploration and facilitating the discovery of innovative shapes. Furthermore, in the multi-objective optimization process targeting both hydrodynamic performance and structural strength, the reduced dimensionality of the design variables accelerates convergence while maintaining a broad and meaningful design space. The proposed methodology demonstrates the VAEGAN model's ability to generate diverse and effective turbine blade designs, highlighting its potential as a powerful tool in advancing HATT technology.
Water wave radiation by an array of bottom-mounted surface-piercing concentric cylinders
Authors: Zhang Mohan , Wang Guangyuan , Yin Bo
Published: November 2024

This paper develops a wave radiation analysis model in horizontal oscillation mode for concentric cylindrical arrays with arbitrary numbers and arrangements within the framework of linear potential flow theory. The concentric cylinders have solid inner cylinders and porous outer cylinders, and they are both bottom-mounted and surface-piercing. The porous boundary conditions of the outer cylinders are treated using Darcy's law, and the flow field is divided into one outer region and N (number of cylinders) inner regions with the outer cylinders as the boundary. Employing eigenfunction expansion and region-matching methods, expressions for the radiation velocity potential of each region are obtained, and then expressions of the added mass and damping coefficient of each cylinder are obtained. Following a rigorous verification of the results against published literature, this paper proceeds to analyze the impact of various parameters, including oscillation modes, outer cylinder permeability, radius ratio, spacing, and the number of cylinders, on the wave radiation characteristics of tandem-arranged cylindrical arrays. The research reveals that when the oscillation direction of the structure is parallel with its arrangement direction, the hydrodynamic coefficient curves exhibit significant spikes, attributed to the influence of the Dirichlet trapped mode. Outside the peak regions, the hydrodynamic coefficient curves display regular fluctuations, which are attributed to the alternating occurrence of constructive and destructive interference effects within the wave field.
Highly separated transitional shock-wave/boundary-layer interactions: A spatial modal study
Authors: Nel Philipp L. , Schreyer Anne-Marie , Schrijer Ferry F. J. , van Oudheusden Bas W. , Swoboda Marius
Published: November 2024

At cruise altitudes, the Reynolds number may become sufficiently low to allow a laminar boundary layer to persist on the suction side of a transonic fan blade up to the shock-wave/boundary-layer interaction (SBLI). In such a transitional SBLI with sufficiently large shock-induced separation, a shock oscillation mechanism occurs, with the source at the upstream growth (until a critical length) and natural suppression (through shear layer instabilities) of the separation bubble. The oscillation cycle is characterized by a temporarily vanishing upstream laminar part of the separation bubble. The suppression of this laminar part is accompanied by downstream advection of turbulence and subsequent entrainment into the bulk separation bubble, affecting the reflected shock movement. In order to study the spatial behavior of the mechanism, particle image velocimetry of a highly separated transitional oblique SBLI at Mach 2.3 is conducted in the high speed aerodynamics laboratory of Delft University of Technology. Statistical quantities, including root mean square velocity fluctuations, phase averages, and spatial modes from proper orthogonal decomposition, are investigated. The entrainment strength varies depending on the phase of the oscillation, and the turbulent shear layer is not fully developed. The main growth and shrinking mode of the separation bubble were extracted, which affects the slip line region size and shock position. Secondary modes that affect the shear layer undulation and upstream effects were also extracted. The study provides quantitative analyses of an important shock oscillation type, with the focus on capturing the separation bubble size variation and upstream effects.
A novel micromixer based on coastal fractal for manufacturing controllable size liposome
Authors: Chen Xinkun , Zhai Junlong , Chen Xueye
Published: November 2024

The traditional lipid preparation methods are complex, time-consuming, and consume a large amount of reagents, increasing costs and difficulties. Although microfluidic technology is considered a promising solution, achieving controllable liposome production with a simple and inexpensive microfluidic mixing device remains an important problem. This paper presents a wall-type micro-mixer based on coastal zone fractals. Four parameters related to the geometric shape of the coastline fractal in the microchannel are used as design variables, and the mixing index is the objective function. Single-objective optimization numerical analysis of the primary wall-type fractal baffle micromixer under four Reynolds numbers conditions yields the optimal structural configuration. Visualization experiments verify the correctness and accuracy of the numerical simulation, and the optimized mixer is used to produce liposomes. The results show that the micro-mixer with the optimal double-sidewall cross arrangement enhances chaotic convection and improves mixing efficiency. At Re = 0.1 and Re = 100, the mixing efficiency reaches 99%, 50.44% higher than the reference design. By changing the relative flow rates of lipid and aqueous solutions, microfluidic blank liposomes with a particle size of 165.12 ± 11.6 nm and a polydispersity index of 0.35± are obtained. This wall-type fractal micro-mixer has broad application prospects due to its high mixing efficiency.
Spatiotemporal transcriptomic map of glial cell response in a mouse model of acute brain ischemia
Authors: Zucha Daniel , Abaffy Pavel , Kirdajova Denisa , Jirak Daniel , Kubista Mikael , Anderova Miroslava , Valihrach Lukas
Published: November 2024

The role of nonneuronal cells in the resolution of cerebral ischemia remains to be fully understood. To decode key molecular and cellular processes that occur after ischemia, we performed spatial and single-cell transcriptomic profiling of the male mouse brain during the first week of injury. Cortical gene expression was severely disrupted, defined by inflammation and cell death in the lesion core, and glial scar formation orchestrated by multiple cell types on the periphery. The glial scar was identified as a zone with intense cell–cell communication, with prominent ApoE-Trem2 signaling pathway modulating microglial activation. For each of the three major glial populations, an inflammatory-responsive state, resembling the reactive states observed in neurodegenerative contexts, was observed. The recovered spectrum of ischemia-induced oligodendrocyte states supports the emerging hypothesis that oligodendrocytes actively respond to and modulate the neuroinflammatory stimulus. The findings are further supported by analysis of other spatial transcriptomic datasets from different mouse models of ischemic brain injury. Collectively, we present a landmark transcriptomic dataset accompanied by interactive visualization that provides a comprehensive view of spatiotemporal organization of processes in the postischemic mouse brain.
Genomic perspectives on foodborne illness
Authors: Lipman David J. , Cherry Joshua L. , Strain Errol , Agarwala Richa , Musser Steven M.
Published: November 2024

Whole-genome sequencing of bacterial pathogens is used by public health agencies to link cases of food poisoning caused by the same source of contamination. The vast majority of these appear to be sporadic cases associated with small contamination episodes and do not trigger investigations. A “contamination episode” refers to one or more contamination events from a single source over a period of time. We examine clusters of sequenced clinical isolates of
Salmonella
,
Escherichia coli
,
Campylobacter
, and
Listeria
that differ by only a small number of mutations (SNPs) to identify features of the underlying contamination episodes. These analyses provide additional evidence that the youngest age groups have greater susceptibility to infection by
Salmonella
,
E. coli
, and
Campylobacter
than older age groups. This age bias is weaker for the common
Salmonella
serovar Enteritidis than
Salmonella
in general. A large fraction of the contamination episodes causing sickness appear to have a long duration. For example, 50% of the
Salmonella
cases are in clusters that persist for almost 3 y. For all four pathogen species, the majority of the cases were part of genetic clusters with illnesses in multiple states and likely to be caused by contaminated commercially distributed foods.
Salmonella
infections in infants under 3 mo are predominantly acquired from the same contaminated food, pet food, or environmental sources as older individuals, rather than infant formula contaminated during production.
Spesolimab mechanism of action in the treatment of generalized pustular psoriasis
Authors: Visvanathan Sudha S , Hawkes Jason E
Published: November 2024

This video article describes the mechanism of action of spesolimab, which treats generalized pustular psoriasis by inhibiting the IL-36 signaling pathway.
Symmetric vs. chiral approaches to massive fields with spin
Authors: Delplanque William , Skvortsov Evgeny
Published: November 2024

Massive higher spin fields are notoriously difficult to introduce interactions when they are described by symmetric (spin)-tensors. An alternative approach is to use chiral description that does not have unphysical longitudinal modes. For low spin fields we show that chiral and symmetric approaches can be related via a family of invertible change of variables (equivalent to parent actions), which should facilitate introduction of consistent interactions in the symmetric approach and help to control parity in the chiral one. We consider some examples of electromagnetic and gravitational interactions and their transmutations when going to the chiral formulation. An interesting feature of the relation is how second class constraints get eliminated while preserving Lorentz invariance.
Enhanced energy storage performance of lead-free Sr0.7Bi0.2TiO3 ceramics via tape casting
Authors: Liu Shuai , Zhou Jian , Liu Deke , Xu Ran
Published: November 2024

The development of pulsed power technology demands high energy storage density dielectric materials. In this study, Sr0.7Bi0.2TiO3 relaxor ferroelectric (rFE) ceramic thick films were prepared using a tape-casting process. The ceramics exhibit a dense structure and typical rFE hysteresis curves, achieving an energy storage density of 4.77 J cm−3 and efficiency of 94.4%, attributed to the high polarization intensity, low remnant polarization, and low hysteresis loss of rFE. Additionally, the material demonstrates good temperature stability. Moreover, the Sr0.7Bi0.2TiO3 ceramic thick films show advantages in charge-discharge performance, capable of discharging within hundreds of nanoseconds and achieving a power density of 137 MW cm−3. Overall, the Sr0.7Bi0.2TiO3 ceramic thick film exhibits a comprehensive performance advantage in terms of energy storage density, efficiency, and power density. Additionally, the material was fabricated using the tape-casting process, which is compatible with subsequent multilayer ceramic capacitor production, indicating potential for further performance enhancement.
Design and performance study of narrowband polarized colloidal quantum dots photodetector
Authors: You Congya , Liu Ming , Zhang Yi , Wang Xiaoqian , Yan Yong , Yu Songlin
Published: November 2024

Colloidal quantum dot-based (CQD) photodetectors have shown exceptional potential for low-cost, room-temperature broadband imaging. However, the isotropic optical properties of the CQD absorber hinder the capability for multi-dimensional photodetection, such as polarization. Here, we design and theoretically study a CQD photodetector with an encapsulation layer and metal grating layer, which can achieve narrowband polarization sensitivity with a full width at half maximum of 230 nm at a wavelength of 2 μm. We first investigate the effect of the geometric parameters of the architecture. Moreover, we examine the broadband polarized optical properties and analyze the corresponding mechanisms. A large linear polarization ratio of 66 is obtained at an illuminated light wavelength of 2 μm. These results contribute to offering a promising design for constructing narrowband polarized CQD photodetectors, particularly for quantum information processing in the realms of quantum communication and quantum cryptography.
Measurement of dynamic deformation during shock loading using a fiber-optic loop-sensor
Authors: Baohui Yang , Luong Dung Dinh , Gupta Nikhil
Published: November 2024

Characterizing materials under shock loading has been of interest in fields such as protective material development, biomechanics to study the injury mechanics and high-speed aerodynamic structures. However, shock loading of material is a very short duration phenomenon and it is extremely challenging to develop sensors for dynamic measurements under such loading conditions. Optical fiber sensors present the possibilities to allow high resolution measurement of displacement in such high strain rate loading conditions. This work studies the possibility of using a fiber-optic loop sensor (FOLS) based on the principle of power losses from the curved section for dynamic measurements under shock loading conditions. The displacement results obtained from the optical sensors are compared with the traditional strain gauge and digital image correlation (DIC) measurements. The result obtained by the FOLS closely matched the sensitivity and precision of the strain gauges and had higher precision than that of DIC.
Static actuator-sharing algorithm for concurrent control of multiple plasma properties
Authors: Tej Paruchuri Sai , Graber Vincent , Pajares Andres , Schuster Eugenio
Published: November 2024

Simultaneous regulation of multiple properties in next-generation tokamaks like ITER and fusion pilot plant may require the integration of different plasma control algorithms. Such integration requires the conversion of individual controller commands into physical actuator requests while accounting for the coupling between different plasma properties. This work proposes a tokamak and scenario-agnostic actuator-sharing algorithm (ASA) to perform the above-mentioned command-request conversion and, hence, integrate multiple plasma controllers. The proposed algorithm implicitly solves a quadratic programming (QP) problem formulated to account for the saturation limits and the relation between the controller commands and physical actuator requests. Since the constraints arising in the QP program are linear, the proposed ASA is highly computationally efficient and can be implemented in the tokamak plasma control system in real time. Furthermore, the proposed algorithm is designed to handle real-time changes in the control objectives and actuators’ availability. Nonlinear simulations carried out using the Control Oriented Transport SIMulator illustrate the effectiveness of the proposed algorithm in achieving multiple control objectives simultaneously.
Design of flexural bottle beam metasurface with resonant pillar-type metamaterials
Authors: Wu Yunhao , Sun Zhaoyong , Tian Yimin , Yang Jun
Published: November 2024

In this paper, we design a flexural metasurface capable of transforming plane or cylindrical waves into bottle shaped beam. The refractive index of the metasurface is calculated by Generalized Snell’s Law and discretized into 5 × 201 lattices, which is finally realized by resonant pillar-type unit cells. Simulation results demonstrate the bottle shaped focusing effect of the metasurface, which remains robust even in the presence of a scatterer inside the bottle beam. This work provides a theoretical and simulation foundation for the application and experiment of bottle beam in flexural wave control.
Renormalized primordial black holes
Authors: Franciolini G. , Ianniccari A. , Kehagias A. , Perrone D. , Riotto A.
Published: November 2024

The formation of primordial black holes in the early universe may happen through the
collapse of large curvature perturbations generated during a non-attractor phase of inflation or
through a curvaton-like dynamics after inflation. The fact that such small-scale curvature
perturbation is typically non-Gaussian leads to the renormalization of composite operators built
up from the smoothed density contrast and entering in the calculation of the primordial black
abundance. Such renormalization causes the phenomenon of operator mixing and the appearance of an
infinite tower of local, non-local and higher-derivative operators as well as to a sizable shift
in the threshold for primordial black hole formation. This hints that the calculation of the
primordial black hole abundance is more involved than what generally assumed. We show the
impact of this phenomenon in a perturbatively non-gaussian scenario, giving also an estimate of
its effect on the threshold for primordial black hole formation.
Combining electron microscopy with atomic-scale calculations—A personal perspective
Authors: Pantelides Sokrates T.
Published: November 2024

I had the privilege and the pleasure to work closely with Stephen J. Pennycook for about twenty years, having a group of post-docs and Vanderbilt-University graduate students embedded in his electron microscopy group at Oak Ridge National Laboratory, spending on average a day per week there. We combined atomic-resolution imaging of materials, electron-energy-loss spectroscopy, and density-functional-theory calculations to explore and elucidate diverse materials phenomena, often resolving long-standing issues. This paper is a personal perspective of that journey, highlighting a few examples to illustrate the power of combining theory and microscopy and closing with an assessment of future prospects.
The resonance effect for the CP asymmetry associated with the process
*
Authors: Yuan 原 Xi-Liang 喜亮 , Lü 吕 Gang 刚 , Wang 王 Na 娜 , Wang 王 Chao 超
Published: November 2024

The direct CP asymmetry in the weak decay process of hadrons is commonly attributed to the weak phase of the CKM matrix and the indeterminate strong phase. We propose a method to generate a significant phase difference through the interference between ρ and ω mesons, taking into account the G-parity allowed decay process of

and the G-parity-suppressed decay process of

in B meson decays. This interference can lead to notable changes in the CP asymmetry within the interference region. Additionally, we calculate the integral results for different phase space regions of the four-body decay process. We hope that our work provides valuable theoretical guidance for future experimental investigations on CP asymmetry in these decays.
Leveraging textured flickers: a leap toward practical, visually comfortable, and high-performance dry EEG code-VEP BCI
Authors: Dehais Frédéric , Cabrera Castillos Kalou , Ladouce Simon , Clisson Pierre
Published: November 2024

Objective. Reactive brain–computer interfaces typically rely on repetitive visual stimuli, which can strain the eyes and cause attentional distraction. To address these challenges, we propose a novel approach rooted in visual neuroscience to design visual Stimuli for Augmented Response (StAR). The StAR stimuli consist of small randomly-oriented Gabor or Ricker patches that optimize foveal neural response while reducing peripheral distraction. Approach. In a factorial design study, 24 participants equipped with an 8-dry electrode EEG system focused on series of target flickers presented under three formats: traditional Plain flickers, Gabor-based, or Ricker-based flickers. These flickers were part of a five-class code visually evoked potentials paradigm featuring low frequency, short, and aperiodic visual flashes. Main results. Subjective ratings revealed that Gabor and Ricker stimuli were visually comfortable and nearly invisible in peripheral vision compared to plain flickers. Moreover, Gabor and Ricker-based textures achieved higher accuracy (93.6% and 96.3%, respectively) with only 88 s of calibration data, compared to plain flickers (65.6%). A follow-up online implementation of this experiment was conducted to validate our findings within the frame of naturalistic operations. During this trial, remarkable accuracies of 97.5% in a cued task and 94.3% in an asynchronous digicode task were achieved, with a mean decoding time as low as 1.68 s. Significance. This work demonstrates the potential to expand BCI applications beyond the lab by integrating visually unobtrusive systems with gel-free, low density EEG technology, thereby making BCIs more accessible and efficient. The datasets, algorithms, and BCI implementations are shared through open-access repositories.
Functional connectivity of stimulus-evoked brain responses to natural speech in post-stroke aphasia
Authors: Mehraram Ramtin , De Clercq Pieter , Kries Jill , Vandermosten Maaike , Francart Tom
Published: November 2024

Objective. One out of three stroke-patients develop language processing impairment known as aphasia. The need for ecological validity of the existing diagnostic tools motivates research on biomarkers, such as stimulus-evoked brain responses. With the aim of enhancing the physiological interpretation of the latter, we used EEG to investigate how functional brain network patterns associated with the neural response to natural speech are affected in persons with post-stroke chronic aphasia. Approach. EEG was recorded from 24 healthy controls and 40 persons with aphasia while they listened to a story. Stimulus-evoked brain responses at all scalp regions were measured as neural envelope tracking in the delta (0.5–4 Hz), theta (4–8 Hz) and low-gamma bands (30–49 Hz) using mutual information. Functional connectivity between neural-tracking signals was measured, and the Network-Based Statistics toolbox was used to: (1) assess the added value of the neural tracking vs EEG time series, (2) test between-group differences and (3) investigate any association with language performance in aphasia. Graph theory was also used to investigate topological alterations in aphasia. Main results. Functional connectivity was higher when assessed from neural tracking compared to EEG time series. Persons with aphasia showed weaker low-gamma-band left-hemispheric connectivity, and graph theory-based results showed a greater network segregation and higher region-specific node strength. Aphasia also exhibited a correlation between delta-band connectivity within the left pre-frontal region and language performance. Significance. We demonstrated the added value of combining brain connectomics with neural-tracking measurement when investigating natural speech processing in post-stroke aphasia. The higher sensitivity to language-related brain circuits of this approach favors its use as informative biomarker for the assessment of aphasia.
Improvements in Wave Age-Based Sea and Swell Separation for Offshore Industry Applications
Authors: Kistner S , Caichac D , Cariou R , Jensen P M , Sanchez R B , Grode P D
Published: November 2024

For offshore wind turbines, an accurate description of the wave conditions is crucial for their design, construction, installation, maintenance, and operation. Typical sea states in the open ocean are often a combination of wind-sea and swell systems which cannot be fully described by a single set of parameters. In such cases the wave conditions are better defined by separating and quantifying the individual wave systems. In this paper, the wave age method has been revisited, and a modification has been proposed to add more functionality to better describe the wind/wave alignment of the wind-sea. A qualitative analysis was performed using offshore spectral energy data from a global wave model. The analysis was carried out for four different geographical locations: the Philippine Sea, the North Sea, the Atlantic Ocean, and the Pacific Ocean. The analysis compares the wind-sea and swell partitions separated by the standard and modified wave age methods. It shows an improved description of the wind-sea compared to the standard equation, especially in the case of high wind speed events and where the wind-sea partition is expected to dominate most of the spectral energy.
Collocating wind data: A case study on the verification of the CERRA dataset
Authors: Rouholahnejad F , Meyer P J , Gottschall J
Published: November 2024

Wind resource assessment often relies on reanalysis data or meso-scale models due to the challenges and costs associated with on-site measurement campaigns, especially in offshore locations. While these datasets offer extensive spatial coverage, they often provide the desired parameters on a coarse grid only. The spatial averaging over the grid and the low frequency of the outputs hinders the model’s ability to capture the short-term wind speed variability and events with a time scale of a few minutes to a few dozen of minutes. In this paper we investigate the temporal scales of the wind events resolved by the Copernicus European Regional Re-Analysis (CERRA) dataset, ERA5, and an in-house regional down-scaling of ERA5 using the WRF model by comparing them against measurements. We propose a method to collocate the two sources of wind data (measured and modeled), focusing on the verification of CERRA with respect to first and second-order statistics in the North Sea. The results highlight the superiority of CERRA compared to ERA5 in estimating the wind speed distribution, improving the 95th percentile error from -0.85 to -0.19 ms−1 and the average bias from -0.286 to -0.004 m s−1 across all locations. The wind speed change over one hour is underestimated by both CERRA and ERA5 when collocated with 10-minute measurements at the full hour. However, hourly averaged measurements align well with CERRA’s wind speed variation predictions, while an averaging window of 3.5 hours is needed to align with ERA5’s hourly wind speed changes. The results showed that the synthetic wind speeds exhibit optimal correlation with the measurements when the measurements are averaged over 4.5 to 7 hours, depending on the modeled dataset. This time scale corresponds to a length scale of 160-250 km, assuming a mean wind speed of 10 m s−1, which falls within the meso-scale range. The study contributes to the understanding of model validation in offshore wind energy studies, with the potential to enhance wind resource assessment calculations and improve the results of long-term extrapolations.
Application of systems safety principles for O&M of floating offshore wind
Authors: Rowell D , McMillan D , Carroll J
Published: November 2024

The offshore wind industry is growing rapidly and is also a high risk industry with unique safety challenges. As the industry grows, more research is needed to make sure it operates safely and provides a workplace in which all involved can go home free of injury. The adoption of floating wind turbines brings new hazards and increased complexity to offshore wind operations and maintenance. Floating wind operations will involve the development of new deepwater sites and require the adoption of new strategies such as floating to floating transfers and towing operations. As the complexity of offshore operations increases it is important that the understanding of the hazards involved are developed. Floating wind is a new branch of the offshore wind industry and as technologies and systems have yet to become established there is the opportunity to do things differently and embed safety improvements in the industry from the outset.

This study has looked at the potential application of systems safety theories to floating wind operations and maintenance. The application of systems engineering to improve safety performance has been growing across many industries in recent years. Systems safety considers that safety is an emergent property of a complex system that is a result of many interacting factors. This study looks at how systems safety could be applied to the emerging floating wind industry to build safety into the industry at the earliest stages.

This study reviewed the applications of systems safety across similar industries and the offshore wind industry. It then looks at existing hazards of floating wind that have already been identified in the literature and completed a systems theory hazard analysis of floating wind O&M activities. This involved the mapping of the safety control structure for floating wind operations and the identification of potential gaps between the safety controls and safety requirements. It then explores how systems safety processes could be applied to floating wind and makes recommendations for how these could be implemented to the emergent industry.

The study found existing research of systems safety applied to the offshore wind industry is currently very limited. Its application has been successful in similar industries and there is potential for a systems safety approach to be used in the development of floating wind operations and maintenance. The systems theory hazard analysis can help identify potential systemic risks arising as a result of the interaction of multiple systems. It can be used to develop appropriate control structures to manage safety and could also be used for the identification of leading indicators to manage safety performance.
Predictive Modeling of Semi-Submersible Floater Motion Using Bi-LSTM Model
Authors: Mian H H , Siddiqui M S , Keprate A , Mathew S
Published: November 2024

Floating offshore wind turbines (FOWTs) are emerging as a promising renewable energy solution, tapping into the vast wind resources in deep-sea locations. Accurate predictions of heave, pitch, sway, roll, yaw, and surge are essential to ensuring the structural integrity and power generation efficiency of FOWTs. Traditional methods relying on potential flow theory to predict FOWTs’ hydrodynamic responses involve simplifications that may not capture real-world complexities. Although computational fluid dynamics (CFD) simulations offer accuracy, they are computationally expensive. This study explores the use of Bi-directional long-short-term memory (Bi-LSTM) neural networks as an alternative to address computational challenges in predicting FOWTs’ hydrodynamic responses. These networks excel at handling time series data, capturing temporal correlations crucial for understanding FOWT floater motion dynamics. They also effectively capture bidirectional dependencies, enhancing their suitability for this application. The model considers various input parameters, including wave amplitudes, periods, steepness, directions, and floater design characteristics such as stifness, pre-tension, and the free length of mooring lines. The Bi-LSTM model is trained using a subset of the CFD dataset generated for the scaled OC5 semi-submersible platform with mooring, reserving the remainder for validation and testing. The comparison between simulated and predicted motion demonstrated a strong correlation in surge but noticeable discrepancies in heave and pitch. FFT analysis highlighted consistent frequency components but variations in magnitude, suggesting areas for model sensitivity improvement and further investigation into wave interaction dynamics. The correlation coefficients revealed a strong positive correlation for the surge motion, while the heave and pitch motions showed slightly lower correlation coefficients, suggesting better performance in predicting the surge.
Static analysis and non-probabilistic reliability evaluation of supporting structure of insulation platform
Authors: Feng Yu , Wu Shaolei , Wang Zhijian , Wang Wei
Published: November 2024

The insulation platform is a kind of high-altitude live working equipment commonly used in complex terrain environments. Due to the harsh working conditions, the safety of the insulation platform is highly required. The supporting structure of the insulation platform is responsible for carrying the operators, which determines the safety performance of the insulation platform. In this paper, static analysis is conducted on the supporting structures of the rotary insulation platform and rotary lifting insulation platform to study their strength and stiffness properties. Then the reliability of supporting structures is analyzed based on the interval non-probabilistic reliability theory and the reliability of structures is evaluated under different size conditions.
Cu@Cu31S16 cathode for high-performance aqueous zinc-ion battery
Authors: Hu Zhenyu , Liu Wan-Qiang
Published: November 2024

Among various battery systems, aqueous zinc-ion batteries demonstrate significant potential for large-scale energy storage applications. However, the relatively large radius of zinc ions makes it challenging for them to intercalate into cathode materials, resulting in a limited variety of host materials suitable for Zn2+ storage. Therefore, researching appropriate cathode materials is a crucial component of the practical application of aqueous zinc-ion batteries. In this study, we prepare two binderless, conductor-less, current collector materials Cu@Cu31S16 cathodes, by in-situ etching of copper foil with a polysulfide precursor solution. The results indicate that Cu31S16 not only exhibits excellent stability and conductivity but also features rapid ion migration kinetics and low Zn2+ diffusion barriers.
Automatic control algorithm for V2G frequency response mode of electric vehicle charging station
Authors: Zhang Yusen , Qi Tianxing , Zhang Chao , Guo Tianhong , Wu Jiangong
Published: November 2024

To solve the problem of excessive fluctuation of the V2G load of the electric vehicle charging pile, this paper proposes an automatic control algorithm for the V2G frequency response mode of the electric vehicle charging pile. The FPGA is used as the core processing unit to collect and process the V2G frequency data of the charging pile; the multiple linear regression model is used to predict the charging and discharging loads, and the automated two-layer control model is established; the sparrow search algorithm is used to optimize the weights and thresholds of the BP neural network to realize the control of the V2G frequency response mode. The experimental results show that the load prediction error of this method is small. After the automatic control, the load fluctuation of the charging pile is small, and the electric vehicle charging pile’s V2G frequency response control effect is better.
Optimal scheduling of distributed generation in smart microgrids: A comprehensive model and efficient algorithm
Authors: Zhang Fan
Published: November 2024

This study proposes an optimal scheduling model for distributed generation (DG) within smart microgrids, incorporating various distributed energy resources (DERs) such as photovoltaic panels, wind turbines, biomass generators, and energy storage systems. To address the complexities of the scheduling problem, we design a hybrid optimization algorithm combining Genetic Algorithms (GA) and Particle Swarm Optimization (PSO). This hybrid algorithm leverages the global search capabilities of GA and the local search efficiency of PSO to achieve robust and efficient convergence to near-optimal solutions. A comprehensive case study based on a real-world smart microgrid system demonstrates the effectiveness of the proposed model and algorithm. The results indicate significant reductions in total operational costs, enhanced renewable energy utilization, reduced grid dependency, and improved system reliability. This research highlights the potential for broader implementation of the model, contributing to the advancement of smart grid technologies and the transition towards sustainable energy systems.
Power grid accident warning based on real-time analysis of hazard sources and weights
Authors: Nan Dongliang , Feng Xiaoping , Li Bin , Zhang Lu , Gao Xing , Liu Huanqing
Published: November 2024

The power grid system has diverse structures consisting of multiple subnets, equipment, and components that are interrelated and mutually influential. At the same time, there are various types of power grid accidents, including short circuits, open circuits, overloads, grounding faults, etc. Each type of fault may have its specific cause and manifestation. This complexity and diversity make establishing a comprehensive and accurate early warning model difficult. Therefore, this study proposes an adaptive warning method based on hazard sources and weighted coefficients for power grid accidents. To transform raw data containing a large amount of redundant information and noise into data with targeted features for representation, power grid accident information feature labels are generated based on weighted coefficients. Based on this, based on the improved YOLOv3, potential risks in the power grid are identified and assessed. Identification based on implementing risk prevention and control measures defines multiple warning levels to achieve adaptive warning of power grid accidents. Test data validation shows that the proposed solution has an accuracy up to 97.85%. There is also a significant improvement in other indicators, all of which remain above 98%. Indicator validation shows that the research method meets the actual process standards. For the entire day period, the precision and recall of the research method remained stable at over 90%.
Zero-carbon-oriented optimal power scheduling of electric vehicles considering V2G response
Authors: Sun Zhoufeng , Chen Hao , Lin Yi , Guo Chuangxin
Published: November 2024

This paper presents an electric vehicle (EV) optimization scheduling method that incorporates vehicle-to-grid (V2G) responses within the framework of a carbon market. Initially, the method characterizes the grid-connected and off-grid operational states of EVs. These states are represented by three types of probability density functions derived from historical data. Subsequently, a V2G response model is formulated based on consumer psychology theory. The approach then integrates the impact of carbon trading on the charging and discharging schedules of EVs, aiming to minimize carbon trading costs. The resulting optimization scheduling model is solved using the CPLEX solver.
Detecting quantum vacuum fluctuations of the electromagnetic field
Authors: Malcolm Aaron R , Sharmila B , Wang Zhi-Wei , Datta Animesh
Published: November 2024

Quantum vacuum fluctuations of the electromagnetic field result in two signatures on a harmonically trapped charged particle: a shift from the natural trap frequency and generation of quantum coherences. We assess the role of the long-wavelength and rotating-wave approximations (RWAs) in estimating this frequency shift. We estimate the magnitude of the frequency shift using parameters from a single-electron cyclotron experiment and also demonstrate how the dependence of the frequency shift on the magnetic field of the cyclotron is tied to the RWA. We expect the frequency shift to be observable in future experiments. We also suggest a possible route to detecting vacuum-generated quantum coherences. These experiments should settle the debate on the choice of approximations and gauge in capturing the effect of the quantum vacuum fluctuations.
A many-body quantum model is proposed as the mechanism responsible for accelerating rates of heat uptake by oceans as anthropogenic heat inputs rise
Authors: Smith G B
Published: November 2024

A recent many-body quantum approach to thermal radiation (Smith GB, et al 2022 J. Phys. Commun.
6, 065004) reveals that the energy capacitance of heated water is about twice its heat capacitance, due to energy stored as local hybrid pairs of photons coupled resonantly to local matter excitations, with pair density weighted by mass density. Energy exchange between photons and localised dipole excitations inside water at steady temperature T, occurs at sites where a hybridisation potential within the Hamiltonian couples local oscillation modes to ‘free’ photon modes. Photon modes in both directions are phase retarded at exit sides of a hybrid site. Optically sharp variations with frequency in the index of refraction n(f) and photon density of states follow. Exit spectral intensities at equilibrium temperature T carry quantum information on the energy density of matter excitations coupled to photons, while occupied hybrid sites are the source of all ‘free’ photons and internal spectral intensities. The matter excitations coupled locally to photons are distinct from those that define specific heat, but in water both arise from molecular oscillations. The energy capacitance CEX(T) of hybrid pairs depends on mass density and is independent of the heat capacitance CHT(T), which sets temperature T. CEX(T) is sensitive to T and doubles as a capacitance of energy and of ‘quantum information’. Expressions for CEX(T) are derived from first principles and applied to water. The density of occupied hybrids is amplified near surfaces by photons reflected off the surface, which create new hybrid pairs, but not extra heat. Energy capacitance CEX(T)+CHT(T) sets dT(t)/dt prior to a new equilibrium state emerging, after input heating rate dQ/dt is switched. Rising atmospheric intensities then raise T, dQ/dt, CEX(T) and CHT(T). The times available to cool overnight are fixed, so that a rising capacitance, adds to energy stored at an accelerating rate.