bluuebunny/crossref_metadata_2025 huggingface dataset:
Are endurance runners at higher risk of depression? Screening for
depression and risk factors
Authors: Scheer Volker , Valero David , Thuany Mabliny , Knechtle Beat , Viljoen Carel , Ruescas Escolano Esther , Valero Burgos Encarna
Published: December 2024

Depression is an important public health issue. In the general adult population,
about 6.7% are affected. Little data are available about endurance runners. We
conducted a prospective survey study screening for depression using the Patient
Health Questionnaire and investigating potential associated risk factors in
endurance runners (≥ 21.1–42.2 km) and ultraendurance runners (≥ 42.2 km).
Statistical analysis included descriptive statistics, predictive techniques, and
regression analysis. A total of n = 601 runners participated (female n=222 and
male n=379; mean age [SD]: 42.8 years [± 10.1]). Overall, 11.3% screened
positive for major depression, particularly female runners compared to male
runners (p=0.002) and endurance runners compared to ultraendurance runners
(p=0.023). No significant differences were observed among performance levels
(elite vs. nonelite). Mild depression was observed in 21.6% of runners. Factors
associated with a higher risk for screening for major depression included age
(p<0.001), particularly runners under the age of 28 years, previous
self-reported history of depression (p<0.001), more frequent weekly workouts
(4–5/wk; p=0.021), weeks lost to injury (p=0.022), and female sex (p=0.025). A
third of endurance and ultraendurance runners screened positive for depression,
highlighting the importance of creating awareness for mental health issues and
potential screening for athletes and providing access to appropriate support
services and education.
Enhancement of third-order optical nonlinearity in effective epsilon-near-zero metamaterials of dielectric/metal/dielectric sandwich nanostructures
Authors: Tan Jiaxing , Liang Shijie , Qin Xiaoqi , Huo Yanyan , Lu Heng , Li Jiangtao , Zhao Songqing , Wang Shuyun , Ning Tingyin
Published: December 2024

We report the enhancement of third-order optical nonlinearity in dielectric/metal/dielectric sandwiches driven by the epsilon-near-zero (ENZ) effect. The lithium niobate (LN) and Au are chosen as the typical dielectric and metal, respectively. The sandwich nanostructure consists of two layers of LN film (90 nm) and an insertion of Au layer of different thicknesses (9, 13, and 17 nm). The ENZ wavelength of LN/Au/LN (LAL) sandwiches is experimentally obtained with a modulation from 0.96 μm (Au layer 17 nm) to 1.33 μm (Au layer 9 nm). The nonlinear refractive index n2 and nonlinear absorption coefficient β are determined at variable near infrared wavelengths using the Z-scan method. The maximum n2=2.31×10−14(6.76×10−15)m2/W and β=−9.20×10−8(−1.94×10−8)m/W are obtained in the LAL sandwich with a 13 nm Au layer of ENZ wavelength 1.088 μm at the wavelength 1.064 μm with a pulse duration of 25 ps (120 fs). The n2 is around 19 and 25 times larger than those in the pure LN film of thickness 180 nm measured at the picosecond and femtosecond time domains, respectively. The enhancement of n2 in LAL sandwiches follows the numerical results obtained from the ENZ effect. Especially, the LN layer and the Au layer have comparable contributions to the effective third-order susceptibility χeff(3), which leads to the reconfigurable χeff(3) by changing the thickness of each layer and further to modulate the n2 and β of the samples. The results offer a promising way to attain large and reconfigurable optical nonlinearities for application in all-optical photonic devices at a specified wavelength.
Numerical simulations of laser-driven experiments of ion acceleration in stochastic magnetic fields
Authors: Moczulski K. , Wen H. , Campbell T. , Scopatz A. , Palmer C. A. J. , Bott A. F. A. , Arrowsmith C. D. , Beyer K. A. , Blazevic A. , Bagnoud V. , Feister S. , Halliday J. , Karnbach O. , Metternich M. , Nazary H. , Neumayer P. , Reyes A. , Hansen E. C. , Schumacher D. , Spindloe C. , Sarkar S. , Bell A. R. , Bingham R. , Miniati F. , Schekochihin A. A. , Reville B. , Lamb D. Q. , Gregori G. , Tzeferacos P.
Published: December 2024

We present numerical simulations used to interpret laser-driven plasma experiments at the GSI Helmholtz Centre for Heavy Ion Research. The mechanisms by which non-thermal particles are accelerated in astrophysical environments, e.g., the solar wind, supernova remnants, and gamma ray bursts, is a topic of intense study. When shocks are present, the primary acceleration mechanism is believed to be first-order Fermi, which accelerates particles as they cross a shock. Second-order Fermi acceleration can also contribute, utilizing magnetic mirrors for particle energization. Despite this mechanism being less efficient, the ubiquity of magnetized turbulence in the universe necessitates its consideration. Another acceleration mechanism is the lower-hybrid drift instability, arising from gradients of both density and magnetic field, which produce lower-hybrid waves with an electric field that energizes particles as they cross these waves. With the combination of high-powered laser systems and particle accelerators, it is possible to study the mechanisms behind cosmic-ray acceleration in the laboratory. In this work, we combine experimental results and high-fidelity three-dimensional simulations to estimate the efficiency of ion acceleration in a weakly magnetized interaction region. We validate the FLASH magneto-hydrodynamic code with experimental results and use OSIRIS particle-in-cell code to verify the initial formation of the interaction region, showing good agreement between codes and experimental results. We find that the plasma conditions in the experiment are conducive to the lower-hybrid drift instability, yielding an increase in energy ΔE of ∼ 264 keV for 242 MeV calcium ions.
Fluid mechanics of Na-Zn liquid metal batteries
Authors: Duczek C. , Horstmann G. M. , Ding W. , Einarsrud K. E. , Gelfgat A. Y. , Godinez-Brizuela O. E. , Kjos O. S. , Landgraf S. , Lappan T. , Monrrabal G. , Nash W. , Personnettaz P. , Sarma M. , Sommerseth C. , Trtik P. , Weber N. , Weier T.
Published: December 2024

Liquid metal batteries have been introduced as promising option to address the needs for new energy storage technologies. Currently, batteries based on sodium and zinc are under development and a favorable option due to their high theoretical cell potential, readily abundant materials, and cost-advantages. Nevertheless, they face the problem of self-discharge, which makes it inevitable to understand fluid dynamics in the whole cell. Motivated by that, several types of fluid mechanic instabilities in Na-Zn liquid metal batteries are identified and discussed here. On the one hand they can jeopardize secure operation, but on the other hand they can also improve mixing and increase the cell efficiency. In doing so, realistic cell as well as operation parameters are included and dimensionless numbers for identifying critical conditions are presented. The phenomena with highest significance for the discussed batteries are solutal convection, swirling flow, electrocapillary Marangoni convection, and droplet formation. Still, many open research questions remain and we aim at motivating researchers to dig deeper into some of these topics to contribute to an improved cell design and performance.
Observation of field-free spin–orbit torque switching in a single crystalline (Ga,Mn)(As,P) ferromagnetic film with perpendicular anisotropy
Authors: Lee Kyung Jae , Lee Sanghoon , Liu Xinyu , Dobrowolska Margaret , Furdyna Jacek K.
Published: December 2024

We report the observation of field-free spin–orbit torque (SOT) magnetization switching in a single layer of (Ga,Mn)(As,P) ferromagnetic film exhibiting perpendicular magnetic anisotropy. The SOT switching phenomenon is characterized by distinct transitions between two Hall resistance (HR) states during current scans. When subjected to an in-plane bias field, the observed switching chirality in the HR hysteresis loop consistently aligns with SOT induced by spin polarization arising from Rashba- and Dresselhaus-type spin–orbit fields within the tensile-strained crystalline structure of the (Ga,Mn)(As,P) film. Remarkably, in the present experiments, we observe SOT switching even in the absence of an external bias field, and with its chirality depending on the direction of initial magnetization. We attribute this field-free switching to symmetry breaking facilitated by an internal coupling field, the orientation of which is determined by the external field experienced as the magnetization is initialized. Further evidence supporting the presence of such a coupling field includes a shift in the field-scan HR hysteresis depending on the direction of initialized magnetization. Structural analysis reveals a surface layer enriched in Mn and O, indicating the presence of oxide-based magnetic structures that are magnetically coupled to the (Ga,Mn)(As,P) film. The temperature dependence of field-free SOT switching corroborates this explanation, as the internal coupling field disappears above 40 K, consistent with the expected magnetic transition of the Mn3O4 structure. Our discovery of field-free SOT magnetization switching in a single-layer film represents a significant advancement, offering a novel pathway for the development of simpler and more energy-efficient spintronic devices.
KdV equation for kinetic Alfvén waves and ionospheric solitons
Authors: Shan Shaukat Ali , Arooj Shanza , Saleem H.
Published: December 2024

The Korteweg–de Vries (KdV) equation is derived for nonlinear kinetic Alfvén waves (KAWs) under the framework of the reductive perturbation method in single ion and bi-ion plasmas. It is pointed out that the KdV equation can be derived following the same normalization of spatial coordinates, which was used to obtain an exact solution of the equations for arbitrary amplitude KAWs [Hasegawa and Mima, Phys. Fluids 21, 87 (1978)]. The KdV equation for KAWs is derived assuming Maxwell velocity distribution for electrons to highlight the appropriate normalization procedure of the nonlinear equations for KAWs in the small amplitude limit. Then, the Kappa distribution of electrons is also considered to investigate the effects of non-thermal particles on linear and nonlinear wave dynamics. The results are applied to single ion oxygen and bi-ion oxygen–hydrogen plasmas of the upper ionosphere. It is found that the presence of 0.4% of protons in oxygen plasma of the ionosphere does not affect the shape of the soliton but the high-energy electrons reduce its amplitude. Present theoretical calculations predict the frequencies of KAWs to lie in the range of 10–30 m and widths of solitons to be larger than 100 m. These estimates are in agreement with the Freja satellite observations [Wahlund et al., Geophys. Res. Lett. 21, 1831 (1994)].
Combinatorial composition-gradient and -aligned CsPb(Br1−xIx)3 films by IR-laser MBE
Authors: Takahashi Ryota , Kuroda Teppei , Dazai Takuro , Sato Toshihiro , Koinuma Hideomi
Published: December 2024

We investigated the combinatorial synthesis and characterization of a halide perovskite CsPb(Br1−xIx)3 composition-gradient film deposited on a SrTiO3(001) substrate using infrared laser molecular beam epitaxy. In halide perovskite materials, the diffusion speed of the halogen ions is high, making it difficult to form a continuous composition-gradient film. This is because halogen ions diffuse across the entire film surface, making it impossible to specify the anion composition that changes at each position. In this study, a contact-shadow mask process was introduced to suppress the interdiffusion of halogen ions. Consequently, a CsPb(Br1−xIx)3 composition-gradient and -aligned film in which the chemical composition of CsPbBr3 and CsPbI3 changed digitally was formed and systematically characterized for the optical bandgap and photoluminescence emission wavelength with respect to the chemical composition of the halogen ion. This deposition process is expected to be promising for exploring halide perovskite materials with complex chemical compositions, such as triple-cation halide perovskites.
Detecting and tracking high-velocity plasmoids produced by a magnetized coaxial plasma gun in visible images
Authors: Li Zhaoxuan , Ye Yang , Kong Defeng , Tan Mingsheng , Zhong Fubin , Wang Mingyuan , Qu Chengming , Zhao Zhihao , Wu Yahao , Zhang Qiaofeng , Wang Chao , Huang Yanqing , Zhang Shoubiao
Published: December 2024

The compact torus (CT) injection device, widely known as a magnetized coaxial plasma gun, creates self-contained magnetic field structures, known as plasmoids, which exhibit high densities and velocities. Owing to its remarkable energy density, the CT injection device holds immense potential for tokamak core fueling, rendering it promising for future fusion reactor applications. This paper presents a novel algorithm, comprising a segmentation module based on the UNet neural network and a tracking module leveraging the simple online and real-time tracking (SORT) algorithm, developed for detecting and tracking plasmoids in visible images. The algorithm is specifically designed for the recently manufactured CT injection system of the EAST tokamak, known as EAST-CTI [Kong et al., Plasma Sci. Technol. 25(6), 065601 (2023)]. Our analysis reveals the presence of multiple plasmoids within the plasma flow ejected by the EAST-CTI system. The UNet convolutional neural network successfully detects these plasmoids, achieving a dice coefficient of 0.813 on the test dataset, indicating high accuracy. Meanwhile, a modified version of the SORT algorithm successfully tracks these plasmoids, demonstrating robust performance without false tracking or identity assignment errors. Overall, the developed algorithm offers critical insights into the evolution characteristics of CTs and meets the requirements of the EAST-CTI system’s visible imaging diagnostics. This advancement creates a favorable environment for extensive data analysis using imaging data in future research endeavors.
Polarization-rotation-driven modulation of second harmonic generation in van der Waals layered ferroelectric CuInP2S6
Authors: Hu Yiqi , Gao Han , Zhou Zhou , Wang Shun , Li Qiankun , Luo Zhongshen , Feng Runcang , Hou Yanfei , Ying Tianhao , Weng Yuyan , Han Yibo , Fang Liang , You Lu
Published: December 2024

Two-dimensional van der Waals (vdW) ferroelectrics, renowned for their spontaneous breaking of inversion symmetry and finite electric polarization, are pivotal in nonlinear optics and low-power nanoelectronics. Prior studies primarily focused on materials exhibiting out-of-plane or in-plane ferroelectric polarization, whose rotational degrees of freedom are commonly overlooked. Herein, we experimentally validate the existence of a weak yet symmetry-allowed in-plane polarization in the low-symmetry vdW ferroelectric CuInP2S6 by rigorous structural analysis and vectorial property characterizations. Remarkably, the magnitude of this in-plane polarization is tunable via an interface-induced electric field, leading to a significant contrast in second harmonic generation between oppositely polarized domains. Based on this unique rotational capability of electric polarization, we demonstrate an electrically tunable second-order optical emission in a fabricated vdW ferroelectric capacitor. Our findings highlight the intricate interplay between crystal symmetry and tensorial physical properties, providing a novel pathway for manipulating nonlinear optical functionalities in vdW layered ferroelectrics.
Comprehensive overview of detection mechanisms for toxic gases based on surface acoustic wave technology
Authors: Li Xue , Feng Qingyi , Guo Yuanjun , Lv Haifeng , Zu Xiaotao , Fu Yongqing
Published: December 2024

Identification and detection of toxic/explosive environmental gases are of paramount importance to various sectors such as oil/gas industries, defense, industrial processing, and civilian security. Surface acoustic wave (SAW)-based gas sensors have recently gained significant attention, owing to their desirable sensitivity, fast response/recovery time, wireless capabilities, and reliability. For detecting various types of targeted gases, SAW sensors with different device structures and sensitive materials have been developed with diversified working mechanisms. This paper is focused on overviewing recent advances in working mechanisms and theories of dominant sensitive materials and key mechanisms/principles for targeting various gases in the realm of SAW gas sensors. The basic sensing theories and parameters of SAW gas sensors are briefly discussed, and then the major influencing factors are systematically reviewed, including the effects of various sensitive layer materials, temperature/humidity, and UV illumination on the overall performance of SAW gas sensors. We further highlight the relationships and adsorption/desorption principles between sensing materials and key targeted gases, including NH3, NO2, H2S, explosive gases of H2, and 2,4,6-trinitrotoluene, and organic gases of isopropanol, ethanol, and acetone, as well as others gases of CO, SO2, and HCl. Finally, we discuss key challenges and future outlooks in designing methodologies of sensing materials and enhancing the performance of SAW gas sensors, offering fundamental guidance for developing SAW gas sensors with good sensing performance.
Study of phase decoherence in GeSn (8%) through measurements of the weak antilocalization effect
Authors: Bradicich Adelaide , Petluru Priyanka , Davari Shiva , Zhao Haochen , Gangwal Siddhant , Liu Chia-You , Vasileska Dragica , Zeng Yuping , Churchill Hugh , Li Jiun-Yun , Lilly Michael P. , Lu Tzu-Ming
Published: December 2024

Alloying germanium with tin offers a means to modulate germanium's electronic structure, enabling a greater degree of control over quantum properties such as the retention of the phase or spin of the electron wave. However, the extent to which the presence of high dopant concentrations in GeSn alters these quantum behaviors is poorly understood. Here, we investigate the role of dopant concentrations on phase coherence through measurements of the weak antilocalization (WAL) effect at temperatures between 30 mK and 10 K in p-GeSn (8%) thin films, which were doped to a series of carrier densities on the order of 1012cm−2. Phase coherence and spin–orbit lengths were extracted from the magnetoconductivities using the 2D Hikami–Larkin–Nagaoka model. Phase coherence lengths peaked at 577, 593, and 737nm for the low-, mid-, and high-density samples, while upper limits on the spin–orbit lengths of less than 25nm were relatively independent of carrier density and temperature. The phase coherence lengths increased as the temperature decreased but changed only minimally with carrier density, contrary to common models of temperature-dependent inelastic scattering. Saturation of the phase coherence lengths occurred below 600mK. Based on these findings, intrinsically generated inelastic scattering mechanisms such as two-level systems or impurity band scattering likely contribute to phase decoherence in these alloys. Our results provide insight into the inelastic scattering mechanisms of GeSn, while suggesting a need for further investigation into phase decoherence mechanisms in doped group-IV alloys.
Similarity of scaled-down tests of water entry slamming considering the effects of atmospheric pressure and density
Authors: Fan Shiqi , Yao Xiongliang , Ma Guihui , Lu Jiaxing , Lu Chenxin , Chen Jialiang , Wang Linlin , Ji Jianing
Published: December 2024

The water entry cavity and load characteristics obtained through scaled-down tests are correlated with the atmospheric pressure and density at the free surface. The evaluation of the influence of the cavitation number and atmospheric density coefficient is highly essential for scale tests to improve the prototype prediction accuracy. Focusing on the similarity criterion simulations and load prediction of the scaled-down tests, this study conducts the simulation tests of the water entry characteristics of the scaled-down model under different environments: normal pressure, reduced pressure, and reduced pressure and heavy gas replacement. Moreover, the influence of the cavitation number and atmospheric density coefficient on the multiphase flow, slamming load, and air cushion effect is discussed. The “air cushion effect” is formed at the top of the vehicle during water entry process, which affects the peak narrow pulse width slamming load. Furthermore, the “air cushion” experiences expansion–stability–rupture–escape with increasing water invasion depth. As the atmospheric pressure decreases, the gas tends to thin and the retention inertia weakens. The decrease in the “air cushion” buffering capacity leads to the increase in the slamming load and the expansion of the cavity scale formed by the liquid. Excessive simulation of the dynamic pressure results in the delayed closure of the cavity surface and the slow fall of the water curtain. As the atmospheric density increases, the retention inertia of gas increases because of the increase in the molecular mass, the slamming load gradually decreases, and the closure time of the cavitation and water curtain decreases. The research results of this paper provide some reference for the similarity transformation of the scaled-down test and the pre-research of the prototype.
Numerical analysis and data-driven optimization of energy harvesting efficiency from wake-induced vibration in a multi-cylinder configuration
Authors: Awadallah Mohamed O. , Abdelmigid Tamer A. , Hassan Amr Ali , el Moctar Ould , Jiang Changqing
Published: December 2024

Wake-induced vibrations (WIV) in multi-cylinder configurations have demonstrated greater energy harvesting efficiency in hydrokinetic applications compared to conventional vortex-induced vibrations (VIV) of a single cylinder. However, the complex fluid-structure interactions make it challenging to identify optimal configurations for maximum power output, as extensive simulations across numerous parameter combinations lead to substantial computational costs with traditional computational fluid dynamics (CFD) methods. To address this challenge, we developed a data-driven model using automated machine learning (AutoML) techniques, focusing on four key parameters: spacing, diameter, damping, and reduced velocity. Trained on comprehensive datasets from validated CFD simulations, this model integrates multiple algorithms to predict the power efficiency of WIV systems with high accuracy. Our approach enables rapid and precise evaluations of power efficiency across a broad range of configurations, significantly reducing the computational burden compared to traditional CFD approaches. The results indicate that optimal configurations, characterized by larger upstream cylinder diameters, higher damping ratios, and ideal spacing ratios, can achieve power generation efficiencies of up to 59.15%. Further analysis of vorticity contours reveals that synchronized interactions between upstream vortex shedding and downstream structure motions enhance WIV, thereby improving energy harvesting efficiency.
Design of an ultrasonic flowmeter using a cow horn-shaped structure and secretary bird optimization algorithm-back propagation neural network algorithm
Authors: Fang Lide , Wang Zhongliang , Sun Yiqian , Sun Jianzhang , Su Limin , Wang Mi
Published: December 2024

A novel dual-channel ultrasonic flowmeter based on the time-difference method is proposed, aiming at solving the measurement error due to the installation angle of the transducers and improving the measurement accuracy. The angle error is eliminated by optimizing the ultrasonic propagation path so that it is parallel to the fluid flow direction. The pipeline design is optimized to reduce the pressure loss to ensure high-precision measurements at different flow rates. In addition, in order to solve the measurement accuracy problem caused by the transducer position, the measurement results of the two channels are fused by Secretary Bird Optimization Algorithm-Back Propagation Neural network, which reduces the error of the measurements and improves the overall accuracy of the measurements. The results of system error analysis and uncertainty evaluation show that the calibrated flowmeter has a maximum relative error of 0.6% and a maximum repeatability of 0.7%, which proves its reliability and effectiveness in fluid measurement.
An efficient approach for blood transport in complex interlinked micro-circulatory network
Authors: Mahawar Manoj , Soni Bharat , Nayak Ameeya Kumar
Published: December 2024

The flow domain of the micro-circulatory network provides additional flow resistance to the blood due to the additional friction forces associated with the fluid interface and the solid–fluid interface. Fahraeus–Lindqvist effect facilitates the blood flow by partitioning it into two layers, plasma and red blood cell, that minimize the flow resistance. In this article, a lumped parameter-based approach is interfaced with the theory of dynamical systems to understand the comprehensive blood flow mechanism in the complex micro-circulatory network in terms of quantified resistance, where the blood obeys non-Newtonian characteristics. The dynamic flow resistance signifies the importance of fluid rheology and its dependence on the network topology. It is observed that hematocrit distribution plays a vital role in flow dynamics and may cause flow instability. The advantage of this model relies on the fact that the equivalent network resistance can act as ubiquitous parameters to understand complex flow dynamics. The results demonstrated that the micro-circulatory network could possibly help to handle the clinical implacability and computational efficiency to further improve the medical diagnostic efficacy.
A comparison of h- and p-refinement to capture wind turbine wakes
Authors: Kessasra Hatem , Cordero-Gracia Marta , Gómez Mariola , Valero Eusebio , Rubio Gonzalo , Ferrer Esteban
Published: December 2024

This paper investigates a critical aspect of wind energy research—the development of wind turbine wake and its significant impact on wind farm efficiency. The study focuses on the exploration and comparison of two mesh refinement strategies, h- and p-refinement, in their ability to accurately compute the development of wind turbine wake. The h-refinement method refines the mesh by reducing the size of the elements, while the p-refinement method increases the polynomial degree of the elements, potentially reducing the error exponentially for smooth flows. A comprehensive comparison of these methods is presented that evaluates their effectiveness, computational efficiency, and suitability for various scenarios in wind energy. The findings of this research could potentially guide future studies and applications in wind turbine wake modeling, thus contributing to the optimization of wind farms using high-order h/p methods. This study fills a gap in the literature by thoroughly investigating the application of these methods in the context of wind turbine wake development.
Energy amplification in plasma crystals due to multiple torsions
Authors: Carmichael Calvin , Martinez-Ortiz Jorge , Adamson Parker , Matthews Lorin , Hyde Truell
Published: December 2024

Interacting torsions are examined within a two-dimensional monolayer crystal suspended in an argon complex plasma for 1–10 W discharge powers and pressures of 135–155 mTorr. Two torsions embedded in a lattice are shown to amplify the kinetic energy and range of motion of particles located between the torsions to nearly three times that observed in single torsion systems. It is also shown that multiple torsions can interact via amplified particle energy when separated by up to 14 interparticle distances (Δ). The torsion separation distance also showed a positive linear trend with power and a slightly positive correlation with the pressure. This amplification of energy is possible due to the fact that multiple torsions in a lattice increase the interparticle distance of the lattice by 16% more than single torsion systems, leading to additional freedom of motion in the lattice plane. These combined findings show that multiple torsions heat the lattice differently depending on their separation from the other torsion. The midpoint particles between torsions absorb the majority of energy from the two torsions, and energy addition at the midpoint is nonlinear. The addition of more torsions to the lattice may lead to melting of the plasma crystal.
Experimental study of hydrodynamic effect of loading and longitudinal variations of the center of gravity on the performance of a single-step craft in calm water
Authors: Kandelous Mohsen Mollaei , Ghadimi Parviz
Published: December 2024

Performance of stepped planing vessels is notably influenced by loading and longitudinal position of the center of gravity. These factors directly affect trim angle, rise, total resistance due to motion, and overall hydrodynamic efficiency. This study experimentally investigates a 2.5 m Fridsma series model with 20° deadrise angle, length-to-width ratio of 5, step distance of 28% of the overall length from the transom, and step height of 4% of the model's width. It involves testing the model with two different weights: 63 and 76.6 kg, corresponding to load coefficients of CΔ=0.5 and CΔ=0.61. Center of gravity is placed at 0.8 m (32%), 0.85 m (34%), and 0.9 m (36%) from the transom. Experiments are conducted at speeds of 1, 2, 3, 4, 5, 6.5, and 8 m/s, which correspond to beam Froude numbers of 0.45, 0.9, 1.35, 1.8, 2.26, 2.9, and 3.6, respectively. The results indicate that increasing the load from 63 to 76.6 kg leads to approximately 12% increase in static trim across all center of gravity positions. The final trim is shown to increase by around 15% at all tested speeds. Additionally, load variations result in 20% rise in the rise up and total resistance. The model achieves optimal performance with load coefficient CΔ=0.61 and center of gravity at 36% of the overall length from the transom, showing the lowest resistance to weight ratio. Overall, the findings reveal that optimizing internal load distribution and LCG placement can enhance the boat's hydrodynamic efficiency, resulting in improved speed, stability, and fuel economy under different operational conditions.
Numerical study of vortex–bubble interaction mechanism in bubble breaker using the volume of fluid and large eddy simulation method
Authors: Ji Junhong , Li Changqing , Li Nan , Li Deqiang , Xu Pengtao , Sun Jiaqi
Published: December 2024

Effectively removing or reducing the number of bubbles doped in a material is of great significance to stabilize product characteristics and improve production safety. In this paper, the volume of fluid method and large eddy simulation method are used to numerically simulate the bubble dynamics in unsteady turbulence near a four-blade propeller in a bubble breaker at different speeds. The results show that the final rupture position of the bubble occurs in the main vortex region. The interaction mechanism between the vortex and the bubble involves not only the impact of the small vortex on the bubble but also the influence of the tail vortex pair, which exerts two strong torsional stresses in opposing directions. This interaction ultimately results in the breakup of the bubble. In addition, three different fracture modes were observed: Ring Broken Mode (RBM), Dented pull out Broken Mode (DBM), and Tear Broken Mode (TBM). The bubble breaking process is quantitatively described in terms of vorticity change rate and critical Weber number (We). It is found that DBM does not occur at high rotational speed, and TBM occurs faster and more violently with increase in vorticity change rate. After multiple cycles, the vorticity change in RBM is similar to that at medium speed, and when the change rate reaches its maximum, the size of the fragmentation bubble becomes smaller.
A local and global feature fusion network for Super-Resolution reconstruction of turbulent flows
Authors: Gong Zhicheng , Xu Zili , Zhao Shizhi , Cheng Lu , Qu Jiangji , Fang Yu
Published: December 2024

The resolution of flow fields represents a significant factor influencing the accuracy of turbulent flow analysis. Nevertheless, the acquisition of high-resolution turbulence data remains a challenge due to the limitations imposed by computing resources. The interpolation method, while capable of achieving high-resolution turbulence at low cost, faces challenges in capturing details of turbulent flows. In this study, a local and global feature fusion network (LGFN) is designed for the reconstruction of high-resolution turbulent flows with high quality. First, dual parallel branches made of dense blocks are introduced into the LGFN to extract local features of turbulent flows. Moreover, the features after the first dense block of each branch are summarized into the self-attention block to obtain global features. The extracted local and global features are aggregated through learnable weight parameters to achieve feature fusion. Finally, the fused turbulence features are scaled to the same dimensional size as the high-resolution turbulence through the implementation of multilayer pixel shuffle layers and convolution layers. The effectiveness of the proposed network was evaluated using datasets of forced isotropic turbulence and channel turbulence. The results demonstrate that the reconstructed velocity fields of the LGFN exhibit the highest degree of similarity to the direct numerical simulation results, in comparison with bicubic interpolation, static convolutional neural network, and super-resolution dense connection network results. In addition, compared to alternative methods, the proposed network effectively captures the characteristics of isotropic or anisotropic turbulence even at larger scales.
Modulation of large-scale motions on turbulent/non-turbulent interface in spatially developing compressible mixing layer
Authors: Zhang Ruibo , Wang Xiaoning , Wang Jianchun , Chen Shiyi
Published: December 2024

Direct numerical simulations (DNSs) are conducted to investigate the modulations of large-scale motions (LSMs) on the turbulent/non-turbulent interfaces (TNTIs) in spatially developing compressible mixing layers with convective Mach numbers (Mc) of 0.4 and 0.8. Turbulent statistics, including velocity profiles, turbulent Mach number, normalized growth rate, Reynolds stress, and velocity spectrum, are analyzed to validate the DNS data. At the shear layer center, large-scale high- and low-speed structures are observed, with spanwise rollers being suppressed as the Mach number increases. At the upper layer, the TNTI elevates above the low-speed (negative fluctuating streamwise velocity) large-scale motions (nLSMs) and sinks above the high-speed (positive fluctuating streamwise velocity) large-scale motions (pLSMs). The conditional averages based on LSMs reveal the modulations of LSMs on TNTIs. Across the upper TNTI, nLSMs stimulate positive (upward) transverse velocity and pLSMs stimulate negative (downward) transverse velocity. Under the influence of nLSMs, the jumps in velocity, turbulent kinetic energy (TKE), and vorticity magnitude are larger, as compared to pLSMs. As the convective Mach number increases, small-scale variables are suppressed, while the modulations of LSMs on TNTIs become more pronounced. The lower TNTI exhibits opposite behaviors. It is less affected by LSMs, with less shear and less intense rotation. The jumps of temperature and density increase with increasing convective Mach number. The effect of LSMs on the temperature and density jumps is significant at Mc=0.8.
Hydrodynamic analysis of fish swimming behavior in turbulent river confluences
Authors: Yan Jifeng , Chu Wenhua , Cao Yu , Zhou Qiaoli
Published: December 2024

This study focuses on selecting the most appropriate turbulence model for simulating fish swimming behavior in river confluences. To achieve this, three numerical models—k-ε, k-ω, and large eddy simulation—were compared by running simulations under identical flow conditions and evaluating the results against biological experimental data. Among the models, the k-ω model demonstrated the smallest relative error, consistently within 5% of the experimental results, confirming its superior accuracy and reliability for this application. The k-ω model's ability to capture boundary layer turbulence and near-wall flow dynamics proved essential for studying fish swimming in complex turbulent environments. Simulations revealed that both the flow velocity ratio between the main stream and tributary and the confluence angle are critical factors influencing the flow structure. At higher flow velocity ratios (R = 1/3 and 3/1) or large confluence angles (α ≥ 90°), turbulence intensity increased, leading to more complex vortex formations that significantly impacted fish swimming speed. When the flow velocity ratio (R) is 1/3, the fish can achieve a maximum swimming speed of 2.75 L/s, which is significantly higher than the swimming speed of 1.18 L/s observed when R is 3/1. Additionally, fish closer to the center of the flow field experienced greater turbulence, resulting in higher energy expenditure. The findings provide crucial insights into the hydrodynamic mechanisms driving fish swimming behavior in dynamic aquatic environments.
Rheological characterization and modeling of ultra-high-velocity fluidized submarine landslides
Authors: Guo Xingsen , Sun Junkai , Liu Yihan , Chen Xuejian , Liang Dongfang , Liu Xiaolei
Published: December 2024

Submarine landslides are critical phenomena due to their potential to reshape seabed topography, trigger tsunamis, and compromise offshore infrastructure. Understanding the rheological properties, particularly shear stress and viscosity under high shear rates, is essential for comprehending the dynamics of these landslides, a topic often underexplored in previous research. This study explores the rheological behavior of fluidized submarine landslides, with a focus on in-site sediments from the South China Sea and the Western Pacific Ocean. Samples prepared with varying densities were subjected to extensive rheological testing in the laboratory and analyzed under shear rates of up to 2000 s−1. Results indicated that all samples exhibited non-Newtonian fluid characteristics, showing shear-thinning behavior at low shear rates and shear-thickening behavior at higher shear rates. This transition is attributed to the breakdown of internal sediment structures, leading to changes in viscosity. This study also found that higher water content generally results in lower yield stress and consistency coefficients, while increasing the shear rate reduces the nonlinearity of the fluid's behavior. To model this complex behavior, a piecewise rheological model based on the Herschel-Bulkley framework was proposed. This model effectively captures the variations in rheological properties across different shear rate stages, with critical shear rates influenced by the sediment type and water content. These findings contribute to a deeper understanding of submarine landslides under extreme conditions, and the proposed model offers a more accurate tool for predicting the behavior of fluidized submarine landslides.
Polycomb in female reproductive health: patterning the present and programming the future
Authors: Jarred Ellen G. , Western Patrick S.
Published: December 2024

Epigenetic modifications regulate chromatin accessibility, gene expression, cell differentiation and tissue development. As epigenetic modifications can be inherited via mitotic and meiotic cell divisions, they enable a heritable memory of cell identity and function and can alter inherited characteristics in the next generation. Tight regulation of epigenetic information is critical for normal cell function and is often disrupted in diseases including cancer, metabolic, neurological and inherited congenital conditions. The ovary performs critical functions in female reproductive health and fertility, including oocyte and sex-hormone production. Oocytes undergo extensive epigenetic programming including the establishment of maternal genomic imprints, which are critical for offspring health and development. Epigenetic modifiers also regulate ovarian somatic cells, such as granulosa and theca cells which support oocytes and produce hormones. While ovarian dysfunction contributes to serious ovarian conditions such as primary ovarian insufficiency (POI), polycystic ovary syndrome (PCOS) and ovarian cancers, the roles of epigenetic modifications in the ovary and their contribution to ovarian dysfunction are not properly understood. Here we review recent advancements in understanding Polycomb proteins, important epigenetic modifiers that have emerging roles in ovarian development and maternal epigenetic inheritance. Polycomb group proteins (PcGs) contribute to the faithful establishment of epigenetic information in oocytes, a process essential for normal offspring development in mice. Emerging evidence also indicates that PcGs regulate ovarian function and female fertility. Understanding these and similar mechanisms will provide greater insight into the epigenetic regulation of ovarian and oocyte function, and how its disruption can impact reproductive health and maternal inheritance.
Bibliometric synthesis of intelligent systems in agriculture
Authors: Smaali Samah , Bouanaka Chafia , Smaali Sahar
Published: December 2024

This study undertakes a bibliometric analysis of recent investigations centered on intelligent systems in agriculture, a combined quantitative and qualitative approach is adopted, which is based on Visualization of Similarities (VOS) method. We then map prominent areas of interest, evaluate international collaboration extents, and identify potential research gaps. Aligned with the United Nations’ vision, the Sustainable Development Goals (SDGs) place a spotlight on the interconnection of poverty eradication (SDG 1), zero hunger (SDG 2), and fostering innovation and infrastructure development (SDG 9). The United Nations recognizes the profound challenges posed by global food insecurity, malnutrition, and the increasing vulnerability of the food system to environmental changes. As populations grow and the demand for food surges, there is an imperative to innovate and transform our agricultural and food systems. Adopting advanced technologies, like precision agriculture, remote sensing, Internet of Things (IoT), artificial intelligence (AI), and robotics, offers a promising avenue to address these challenges. Yet, despite the profound implications of these technologies in transforming agriculture, there remains a notable need for comprehensive research in this domain. Enhancing agricultural productivity, reducing resource wastage, and championing sustainability are pressing concerns. This study undertakes a bibliometric analysis of recent investigations centered on intelligent systems in agriculture, sourcing data from the Scopus database. To comprehensively analyze this vast dataset, a combined quantitative and qualitative approach is adopted, which is based on the visualization of similarities (VOS) method. We then map prominent areas of interest, evaluate international collaboration extents, and identify potential research gaps. Our findings offer pivotal insights that can shape the trajectory of future research and development in the agricultural sector. The significance of our analysis extends beyond academic interest. The insights derived hold the potential to catalyze the growth of smart systems in agriculture, addressing global food security challenges in the process. Moreover, by championing sustainable agricultural practices via intelligent systems, our study underscores its alignment with SDGs, notably those aiming at ensuring zero hunger and promoting responsible consumption and production.
A note on the topological synchronization of unimodal maps
Authors: Gianfelice Michele
Published: December 2024

In this note we complete the analysis carried on in Caby et al (2023 Nonlinearity
36 3603–21) about the topological synchronisation of unimodal maps of the interval coupled in a master–slave configuration, by answering to the questions raised in that Paper. Namely, we compute the weak limits of the invariant measure of the coupled system as the coupling strength

k
∈

(
0
,
1
)

tends to 0 and to 1 and discuss the uniqueness of the invariant measure of its random dynamical system counterpart, proving that the convergence of the associated Markov chain to its unique stationary measure is geometric.
Kalman filter time scale algorithm based on noise characteristics of optically pumped cesium clock
Authors: Song Hui-Jie , Dong Shao-Wu , Zhang Yu , Wang Xiang , Guo Dong , An Wei , Qi Yi , Zhang Shougang
Published: December 2024

The time scale algorithm plays an important role in time keeping. Currently, the time scale algorithm primarily adopts the predictability weighting algorithm for microwave clocks. Due to the different working principles and performance of optically pumped small cesium clocks compared with microwave clocks, a new time scale algorithm must be developed to adapt to optically pumped clocks. Based on the noise characteristics of the optically pumped clocks, the state model is established and the time scale is calculated using the Kalman filtering algorithm. The state model of the optically pumped clocks simultaneously considers the effects of white frequency modulation, flicker frequency modulation, and random walk frequency modulation. The proposed algorithm models the flicker frequency modulation for filtering estimation, which effectively improves the stability of the time scale. Here, the flicker frequency modulation is modeled through the linear combination of Markov processes, and the impact of different numbers of Markov processes on the time scale stability is analyzed. Compared with the predictability weighted algorithm, the results obtained by the proposed algorithm demonstrate that the frequency stability of the Kalman filtering time scale based on the noise characteristics was better than that of the predictability algorithm. Taking rapid Coordinated Universal Time (UTCr) as a reference, the frequency stabilities of the time scale based on three optically pumped clocks obtained by the proposed algorithm were 1.14 × 10−14 for 15 days and 5.50 × 10−15 for 30 days.
The production of biogenic carbon and green hydrogen through biomethane pyrolysis: the environmental benefits for the metallurgy sector
Authors: Negro Viviana , Riorda Alessio , Chiaramonti David
Published: December 2024

The iron and steel industry is responsible for around 4% of androgenic CO2 emissions in Europe and 9% worldwide. This is due to the massive use of carbon coke in metallurgy, which is not only linked to energy purposes, but also to the chemical process of iron ore refining. The steel sector urgently needs to find alternative solutions to improve environmental sustainability, with the transition to a low-carbon scenario representing a major challenge. The pyrolysis of methane is gaining more and more attention for the production of hydrogen, as this alternative process to hydrogen production does not generate any CO2 emissions, but provides a solid carbon product that can be re-used in an industrial symbiosis. If biomethane is used, the pathway is even carbon-negative, and generates a net GHG reduction compliant with the EU ETS (Emission Trading Scheme). However, given the high demand for inlet streams in the EU steel sector, the biomethane currently available is not able to meet the entire hydrogen demand assuming that the steel is produced using the DRI-EAF (Direct Reduction Iron-Electric Arc Furnace) route. Only when looking at the European projections for biomethane production in 2050, it is expected that the demand for steel hydrogen can be totally met, in particular by using 48% of the available biomethane, allowing up to 6 million tons of green hydrogen to be produced, and a significant reduction in net CO2 emissions. Finally, the aim of this work is to assess the energy consumption and environmental benefits resulting from the production of green hydrogen and biogenic carbon in Europe for DRI-EAF, compared to the benchmark market (DRI-EAF fed with natural gas) and the electrolysis alternative.