bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of Kuramoto networks subject to large and small fluctuations from heterogeneous and spatially correlated noise
Authors: Hindes Jason , Schwartz Ira B. , Tyloo Melvyn
Published: November 2023

Oscillatory networks subjected to noise are broadly used to model physical and technological systems. Due to their nonlinear coupling, such networks typically have multiple stable and unstable states that a network might visit due to noise. In this article, we focus on the assessment of fluctuations resulting from heterogeneous and spatially correlated noise inputs on Kuramoto model networks. We evaluate the typical, small fluctuations near synchronized states and connect the network variance to the overlap between stable modes of synchronization and the input noise covariance. Going beyond small to large fluctuations, we introduce the indicator mode approximation that projects the dynamics onto a single amplitude dimension. Such an approximation allows for estimating rates of fluctuations to saddle instabilities, resulting in phase slips between connected oscillators. Statistics for both regimes are quantified in terms of effective noise amplitudes that are compared and contrasted for several noise models. Bridging the gap between small and large fluctuations, we show that a larger network variance does not necessarily lead to higher rates of large fluctuations.
Comparative study on the wake dynamics of pump-jet and ducted propeller based on dynamic mode decomposition
Authors: Zhao Xutao , Shen Xi , Geng Linlin , Zhang Desheng , van Esch B. P. M. (Bart)
Published: November 2023

A comparative study on the wake dynamics of a pump-jet propulsor (PJP) and a ducted propeller (DP) is conducted to investigate the effects of the pre-swirl stator and corresponding stator–rotor interaction on the wake evolution and destabilization mechanisms of a PJP system. The flow field analysis, vortex structure identification, and dynamic mode decomposition (DMD) analysis are carried out based on the numerical results obtained from delayed detached eddy simulations. The numerical hydrodynamic loading and flow field of the PJP are compared with experimental results, and they are in good agreement. Compared with the DP, the stator trailing vortices of the PJP interact with the rotor trailing vortices as well as the hub vortex, accelerating their diffusion and viscous dissipation. The pre-swirl stator triggers the generation of secondary vortices and moderates the spiral behavior of tip leakage vortices, which dominates the wake instability of PJP. The DMD analysis revealed that the wake field evolution is primarily characterized by the different mode structures at blade passing frequency and its multiples, especially in the PJP due to its strong stator–rotor interaction. The modal energy decays faster in the PJP wake field owing to its more turbulent and earlier instability. The hub vortex plays an important role in the wake dynamics of the DP.
Binary coding metasurface for broadband and flexible generation of acoustic vortex beams
Authors: Wu Kai , Liu Jing-Jing , Liang Bin , Cheng Jian-Chun
Published: November 2023

Considerable efforts have recently focused on sound vortices imprinted with orbital angular momentum (OAM) yet whose generation generally relies on sophisticated phase modulation, whether through traditional phased arrays or emerging metamaterial methods. Here, we propose and numerically demonstrate a mechanism for broadband generation of acoustic vortices in a simple, flexible, and high-efficiency way through binary-phase-based chirality modulation enabled by building a binary coding metasurface. The metasurface with a theoretically derived phase profile that is implemented with two types of meta-structures is capable of twisting the incident plane wave into a vortex beam with a desired order in a broad band and at the same time enables steering the vortices' propagation direction freewheelingly. The effectiveness of our proposed mechanism is verified by numerically demonstrating the broadband generation of vortex beams carrying different OAMs through a monolayered binary coding metasurface. We further demonstrate the generality and flexibility of our mechanism for generating the multiplexed vortex beams as well as modulating the propagation direction of the output beam by judiciously designing the 1-bit coding sequences of the metasurface. We anticipate our design with capability and simplicity to have far-reaching implications in OAM-enabled applications ranging from high-capacity acoustic communication to contactless particle manipulation.
Effects of different working parameters on the turbulent drag reduction regulated by annular plasma synthetic jet actuators
Authors: Yu Minghao , Jin Yuanzhong , Zheng Borui , Hu Yuzhe
Published: November 2023

Reduction of turbulent drag force is one of important works in the design of airplanes and hypersonic aircrafts. The annular plasma synthetic jet (APSJ) has become an interesting and popular flow control method in reducing the drag of turbulent boundary layers. In this paper, a comprehensive experimental study is carried out on the turbulent drag reduction regulated by an array of annular plasma synthetic jet actuators. The effects of the operating parameters such as the actuation voltage, the pulse frequency and the incoming wind speed on the drag reduction rate are studied and discussed in detail. The performances of the plasma actuator array are evaluated and summarized at multiple working conditions. Finally, the coherent structures of turbulence and the hairpin-like vortices are depicted and discussed. The results show that the optimal drag reduction rate is achieved, as the actuation voltage, pulse frequency and incoming wind speed are Vpp = 7 kV, fp= 50 Hz, and U∞ = 7 m/s, respectively. A resonant coupling phenomenon is observed when the pulse frequency of the actuators approaches the characteristic frequency of the coherent structure. The upward sweep flow induced by APSJ actuators may lead to a reduction of the turbulent drag force, but the downward wash flow leads to an increase in the drag. Present study could provide solid experimental data and a helpful guidance for the drag reduction of an airplane.
Solvent-free transfer of monolayer graphene with recrystallized cyclododecane
Authors: Kim Min Jung , Moreira Gabriel , Lisi Nicola , Kim Namwon , Shim Wooyoung , Lee Gwan-Hyoung , Capasso Andrea
Published: November 2023

Graphene produced by chemical vapor deposition finds applications in a wide range of technologies. However, the transfer of monolayer graphene from the native substrate (commonly Cu foils) to a desired substrate remains challenging. In this study, we report a solvent-free transfer technique for monolayer graphene using a sublimable supporting coating, cyclododecane (CDD). After spin-coating CDD on graphene grown on Cu foil, we rapidly heat the stack at 80 °C to melt and recrystallize the CDD coating. The recrystallized coating top surface becomes composed of larger and interconnected CDD crystals, which form a mechanically strong coating that takes almost 2 h to sublimate completely. Having a bottom surface that closely conforms to graphene's topography, the CDD coating can effectively support graphene during the whole transfer process without compromising its structural integrity, maintaining its superior electrical and optical properties. In this way, CDD becomes capable of transferring monolayer graphene over square centimeter areas. Unlike traditional polymer-based techniques, after transfer, the CDD coating sublimates completely, without the need of any post-transfer cleaning treatment. Our work shows that the CDD coating can be an alternative transfer medium for the efficient and clean transfer of monolayer graphene. This technique paves the way for the widespread adoption of graphene in various applications, including those not compatible with solvents.
Effect of gamma irradiation on
β
-Ga2O3 vertical Schottky barrier diode
Authors: Liu Minwei , Hua Mingzhuo , Tian Xusheng , Wang Zhengxing , Gao Huhu , Wang Wentao , Chen Yiqiang , Zhang Chunfu , Zhao Shenglei , Feng Qian , Hao Yue
Published: November 2023

In this paper, the radiation effect of gamma irradiation (60Co) on the Au/Ni/β-Ga2O3 vertical Schottky barrier diodes (SBDs) was investigated for total doses of about 1 Mrad (Si). The SBDs were characterized by current density–voltage (J–V) and capacitance–voltage (C–V) measurements. Compared with original β-Ga2O3 SBDs, it was found that Schottky barrier height Φb increases from 1.08 to 1.12 eV, the ideality factor n decreases from 1.07 to 1.02, and the specific on-resistance Ron,sp decreases from 3.34 to 2.95 mΩ·cm2 for the irradiated β-Ga2O3 SBDs. In addition, the carrier concentration calculated from the C–V measurements increases slightly after gamma irradiation. The temperature-dependent current–voltage characteristics and conductance-frequency measurements indicate that the Schottky contact interface of β-Ga2O3 SBDs had been slightly improved after irradiation. These results suggest that β-Ga2O3 SBDs have high intrinsic gamma irradiation hardness.
An analytical model of the dynamics of reattaching jets
Authors: Nicholls Chris J. , Tang Brian M. T. , Turner James , Bacic Marko
Published: November 2023

A jet that emerges from a nozzle and attaches to an inclined, setback wall is studied. The reattaching jet is the canonical element of most fluidic devices, and the aim of this paper is to improve the understanding of its dynamics. An analytical model is developed that describes the dynamic behavior of the jet position in response to acoustic excitation. A novel, unsteady jet curvature equation is derived from first principles, which forms the basis of the model. The Görtler velocity profile for a plane, turbulent jet is assumed, and an alternative approach to determining its virtual origin is used. A novel approach to modeling the momentum balance at the jet reattachment point is demonstrated to predict the observed behavior in response to acoustic excitation. The resulting model is linearized at a series of operating points informed by data from the literature at a range of flow rates, wall setback distances, and gas types. A Monte Carlo analysis is conducted to quantify the model sensitivity to parameter uncertainty. The bandwidth of the jet response to acoustic excitation is demonstrated to depend linearly on jet velocity.
Lattice Boltzmann simulations for the drying of porous media with gas–side convection–diffusion boundary
Authors: Sourya Dasika Prabhat , Panda Debashis , Kharaghani Abdolreza , Tsotsas Evangelos , Gurugubelli Pardha S. , Surasani Vikranth Kumar
Published: November 2023

One of the most significant challenges in describing the drying of porous materials is the realistic integration of internal transport phenomena into mathematical models, coupled with the external free flow. However, the intricacies of pore-scale geometry make experimentation and observation very difficult in practice, thereby making modeling techniques a useful tool for the analysis of the drying process. Among the many modeling techniques developed for drying, the lattice Boltzmann method (LBM)-based modeling approach has gained favor in recent years due to its ability to incorporate realistic geometry and transport at the pore scale. Our previous works on Shan–Chen LBM for drying of capillary porous media were based on the Bhatnagar–Gross–Krook collision operator and diffusion interface boundary conditions. This study elucidates the drying of a capillary porous medium under the influence of convection–diffusion boundary conditions at the gas side, using Shan–Chen LBM. The pore-scale effects of convection–diffusion conditions during the drying process are presented in relation to the macroscale drying kinetics. Moreover, the differences between the convection–diffusion kinetics and purely diffusion–dominated kinetics of the drying process are also presented here. This work also aims to incorporate the convection–diffusion transport phenomena into the drying process of a porous medium under the influence of an imposed thermal gradient, establishing and studying the phenomena of stabilization and destabilization of the drying front under the influence of a temperature gradient, thereby extending the lattice Boltzmann method of modeling for the simulation of convection–diffusion drying, both for the isothermal case and the imposition of a thermal gradient.
Study on unsteady natural convection heat transfer of crude oil storage tank based on fractional-order Maxwell model
Authors: Chang Tai , Li Yongming , Jiang Youshi , Li Shuxuan , Chen Xiyu , Ji Yongqiang
Published: November 2023

When considering the natural flow processes in crude oil in static storage tanks, researchers usually treat the nonlinear heat and mass transfer and flow using integer-order models. However, this ignores the nonlinear convection and heat-transfer phenomena that occur; these are dependent on time and space due to the viscoelasticity of crude oil, which is a non-Newtonian fluid. In this work, we examined the time and space dependence of the nonlinear natural convective heat-transfer processes in crude-oil storage tanks. Fractional-order Maxwell and Cattaneo–Vernotte models were applied to the traditional momentum and temperature equations considering the Boussinesq approximation. Based on the L1 discrete format, the fractional-order pressure-correction equation was derived, and an associated solver, CaputoTemporalFractionalFoam (CTfracFoam), was developed to simulate the convection processes in static crude-oil storage tanks. The results show that when α equals 0.1, the maximum velocity in monitoring area 2 is 0.1404 m/s, and the velocity gradually increases as α increases with a maximum value of 1.1468 m/s at 0.9. When the β is 0.1 and 0.2, the temperature changes in the transition region are −5.204 and −0.165 °C, respectively, while when β is greater than 0.2, the temperature changes are all positive values with a maximum value of 1.924 °C at 0.9. Compared with integer-order Fourier heat-transfer and Newtonian fluid-flow models, the developed fractional-order model can describe the natural convection phenomena of non-Newtonian fluids such as crude oil more flexible and accurately.
Investigating the interaction parameters on ventilation supercavitation phenomena: Experimental and numerical analysis with machine learning interpretation
Authors: Kamali Hossein Ali , Pasandidehfard Mahmoud
Published: November 2023

Understanding the optimal values and interactions of parameters within each process is of highest importance. This study is dedicated to exploring the influence of various parameters and their interactions on ventilation supercavitation phenomena through interpretable machine learning (ML) models. In this study, the characteristics of supercavitation on a disk cavitator with enhanced ventilation at different Froude numbers have been examined through both experimental and numerical means. Subsequently, the data generated from the experimental and numerical methods have been employed to create the optimized ML model. Then, to investigate the behavior of important parameters, their interactions with each other, and the resulting impact of these interactions on conditioned cavitation, interpretable machine learning techniques, such as shapley additive explanations, partial dependence plots, and individual conditional expectations, were employed within an optimized ML model. The findings highlight that the ventilation coefficient is the most crucial parameter affecting the characteristics of supercavitation. Ventilation coefficient exhibits a non-linear behavior and performs effectively within the range of 0.06–0.12. Additionally, the water speed parameter and the ratio of the back-body's diameter significantly influence the cavity length and cavitation number. These parameters exhibit complex interactions, shaping the characteristics of blowing supercavitation.
Semi-empirical analysis of leptons in gases in crossed electric and magnetic fields. I. Electrons in helium
Authors: Hildebrandt Malte , Robson Robert E.
Published: November 2023

In this series, we outline a strategy for analyzing electrons and muons in gases in crossed electric and magnetic fields using the straightforward transport equations of momentum-transfer theory, plus empirical arguments. The method, which can be carried through from first principles to provide numerical estimates of quantities of experimental interest, offers a straightforward, physically transparent alternative to “off-the-shelf” simulation packages, such as Magboltz and GEANT. In this first article, we show how swarm data for electrons in helium gas subject to an electric field only can be incorporated into the analysis to generate electron swarm properties in helium gas in crossed electric and magnetic fields and to estimate the Lorentz angle in particular. The subsequent articles in the series analyze muons in crossed fields using similar transport theory, though the absence of muon swarm data requires empiricism of quite a different nature.
Semi-empirical analysis of leptons in gases in crossed electric and magnetic fields. Part II. Transverse compression of muon beams
Authors: Hildebrandt Malte , Robson Robert E. , Garland Nathan
Published: November 2023

This article employs fluid equations to analyze muon beams in gases subject to crossed electric and magnetic fields, focusing, in particular, on a scheme proposed by Taqqu [Phys. Rev. Lett. 97, 194801 (2006)], whereby transverse compression of the beam is achieved by creating a density gradient in the gas. A general criterion for maximizing beam compression, derived from first principles, is then applied to determine optimal experimental conditions for μ+ in helium gas. Although the calculations require the input of transport data for (μ+, He), which are generally unavailable, this issue is circumvented by “aliasing” (μ+, He) with (H+, He), for which transport coefficient data are available.
Abnormal absorption of extremely intense laser pulses in relativistically underdense plasmas
Authors: Serebryakov M. A. , Samsonov A. S. , Nerush E. N. , Kostyukov I. Yu.
Published: November 2023

It is generally believed that relativistically underdense plasmas are transparent for intense laser radiation. However, particle-in-cell simulations reveal abnormal laser field absorption above the intensity threshold of about 3×1024 Wcm−2 for the wavelength of 1 μm. Above the threshold, the further increase in the laser intensity does not lead to an increase in the propagation distance. The simulations take into account emission of hard photons and subsequent pair photoproduction in the laser field. These effects lead to onset of a self-sustained quantum electromagnetic cascade and to formation of dense electron–positron (e+e−) plasma right inside the laser field. The plasma absorbs the laser field efficiently, which ensures the plasma opacity. The role of a weak longitudinal electron–ion electric field in the cascade growth is discussed.
Self-formed interfacial oxide layer minimizes reverse bias dark current in PbS colloidal quantum dot photodiodes
Authors: Yang Qian , Huang Hao-Wen , Xu Gao , Yuan Yu , Jiang Meng-Ting , Zhong Ya-Nan , Gao Xu , Xu Jian-Long , Wang Sui-Dong
Published: November 2023

PbS colloidal quantum dot (CQD) photodiodes possess high photoresponsivity and broad spectral sensitivity, making them tremendously attractive for low-cost short-wave infrared (SWIR) sensing. A critical challenge in achieving high detectivity in SWIR photodiodes is to minimize their reverse bias dark current density (Jdark) and elucidate the origin of Jdark. We demonstrate in this work how the self-formed AlOx at the ZnO/Al interface dramatically reduced Jdark of the PbS CQD SWIR photodiodes. In such a simple and controlled way, the interfacial states were thoroughly passivated by post-exposure to dry air, which could block the dominant pathways for minority hole injection from Al electrode. The treated photodiode showed low Jdark down to 1.58 × 10−7 A/cm2 at –0.5 V, high photoresponsivity of 0.62 A/W, and high specific detectivity of 2.05 × 1012 Jones at 1413 nm, establishing a readily approach to optimizing detectivity in PbS CQD SWIR photodetectors.
Investigation on accuracy of numerical simulation of aerodynamic noise of single-stage axial fan
Authors: Lu Huabing , Xiao Youhong , Liu Zhigang , Yuan Ye , Zhou Peilin , Yang Guanghui
Published: November 2023

The prediction accuracy of turbomachinery aerodynamic noise, particularly in relation to broadband noise with uncertain factors, has long been a challenging issue. Previous studies have not fully comprehended the factors influencing its prediction accuracy, lacking an objective and comprehensive evaluation method. An improved approach combining orthogonal experiment design and principal component analysis is employed to address these limitations. The evaluation method expands the noise metrics and provides a comprehensive assessment of the accuracy of numerical simulation for aerodynamic noise. The evaluation method is utilized to optimize and quantitatively analyze the impact of the refinement size of the core area on noise prediction for single-stage axial fans. Subsequently, the three metrics, namely, Z1, Z2, and broadband noise Z3, are integrated using PCA to form a new integrated optimal metric Ztotal. The influence of different refinement sizes, particularly on Ztotal, is quantitatively examined. The findings reveal that the mesh size of the stator wake (D area) exhibits the most significant influence on noise prediction accuracy, with a calculated weight of 81.3% on noise accuracy. Furthermore, a comprehensive investigation is conducted on the influence of turbulence models and the wall Y+ value on aerodynamic noise. Detached-eddy simulation and large eddy simulation demonstrate effective capabilities in simulating both upstream and downstream turbulent flow characteristics of the stator, enabling accurate prediction of broadband noise. This study presents a set of numerical simulation schemes that achieve precise prediction of turbomachinery aerodynamic noise.
Cavitation flow and noise reduction design of bionic hydrofoil based on orthogonal optimization
Authors: Zhang Jinsong , Wang Xinlong , Yang Chen , Tang Jiaxian , Huang Zhenwei
Published: November 2023

Hydrofoils hold considerable academic and practical significance in the realms of marine science, energy generation, and water-based engineering. They offer enhanced speed, efficiency, stability, and maneuverability. Bionic structures have emerged as potent tools for reducing energy losses and noise in hydraulic machinery, making bionic hydrofoils a hotbed of research activity. While prominent scholars have historically directed their bionic investigations toward airfoils, operating in compressible flow fields, recent research has shifted its focus to hydrofoils. The hydrofoil's operating environment is characterized by water instead of air, featuring incompressible flow, relatively low Reynolds and Mach numbers, and notably, cavitating flow. This study presents the bionic optimization design of a wavy leading edge for the hydrofoil, employing orthogonal experimental theory. The authors establish rankings for structural parameters of bionic hydrofoils and identify optimal parameter combinations, offering an optimization strategy for selecting bionic configurations. Subsequently, the authors conduct a numerical investigation into cavitating flow, integrating the FW–H (Ffowcs Williams and Hawkings) equation for the analysis of cavitation-induced noise. Notably, this research delves into the underlying mechanisms responsible for the efficacy of bionic structures in enhancing hydrodynamic performance, particularly in the reduction of cavitation-induced noise within cavitating flow, an area scarcely explored in formal publications. The results reveal that the amplitude of the wavy leading edge exerts the most significant influence on the lift-to-drag ratio, as well as the far-field sound pressure level, followed closely by the wavelength. When compared with a baseline hydrofoil, the optimized bionic hydrofoil demonstrates a substantial 45% reduction in maximum cavity volume and a noteworthy 1.3 dB reduction in far-field noise sound pressure level. These findings underscore the capacity of the optimized bionic hydrofoil to effectively suppress cavitation and its associated noise. The established optimization strategy, focused on cavitation suppression and noise reduction, lays a robust foundation for subsequent studies involving complex working conditions.
Small-amplitude waves in a floating poroelastic plate forcing by vertical pitching plate
Authors: Wu Q. Y. , Khabakhpasheva T. I. , Ni B. Y. , Korobkin A. A.
Published: November 2023

The linear two-dimensional problem of flexural-gravity waves generated by an oscillating rigid plate build-in a floating poroelastic plate is studied. The problem is coupled. The plate deflections and the hydrodynamics loads are determined at the same time. The liquid under the poroelastic plate is inviscid and incompressible. Dynamics of the floating plate is described by a thin elastic plate equation. Porosity of the floating plate is taken into account only through the liquid flux into the plate. The velocity of the inflow is assumed to be governed by Darcy's law being proportional to the hydrodynamic pressure at the plate/liquid interface. Two cases of the oscillating rigid plate with and without its part in the liquid are considered. The problems are solved by the Fourier transform method for non-zero porosity and by the vertical mode method for elastic plates with zero porosity. The deflection and strain distributions are analyzed depending on the excitation frequency and the porosity. Two models of floating plate porosity, where the hydrostatic pressure is included into Darcy's law (Zavyalova's model) and excluded (Meylan's model), are compared. Plate porosity induces damping to the system. It is shown that the damping rate is non-monotonic with respect to the plate porosity.
High performance CsPbBr3 epitaxial film photodetector with ultralow dark current and record detectivity
Authors: Zhu Luping , Cheng Xueming , Wang Aiwei , Shan Yansu , Cao Xuelei , Cao Bingqiang
Published: November 2023

At present, spin coating is commonly used for perovskite film detectors, which has large photocurrent in the dark state due to the poor control on film growth and low crystal quality. In this Letter, pulsed laser deposition has been introduced to grow high quality CsPbBr3 epitaxial films, and the effect of substrate temperature on the film quality was studied during the epitaxial process. Planar metal–semiconductor–metal photoconductive detectors based on such epitaxial CsPbBr3 thin films with dark current as low as 11 pA at a bias voltage of 2 V was achieved. Under the illumination of a 450 nm laser with a power density of 0.65 μW cm−2, the responsivity, external quantum efficiency, and detectivity of the devices reach 12.796 AW−1, 2996%, and 3.38 × 1014 Jones, respectively. The maximum on/off ratio can be 2.38 × 105 under high-intensity 450 nm laser irradiation of 148 mW cm−2. In contrast, the spin-coated CsPbBr3 film-based detector with the same device configuration exhibit dark current that is two orders of magnitude higher and an on/off ratio of three orders of magnitude smaller than those of the epitaxial film devices. Therefore, due to their high-quality, thickness-control, and easy-integration, such epitaxial perovskite thin films can be used as a platform for the study of more functionalities of halide perovskite semiconductors and related devices.
Effect of roughness on droplet motion in a capillary channel: A numerical study
Authors: Imani Gloire , Zhang Lei , Maweja Jenny , Sun Hai , Fan Dongyan , Ntibahanana Munezero , Hou Lei , Yang Yongfei , Yao Jun
Published: November 2023

This study presents droplet dynamics in a rough capillary channel. Prior studies investigating the effect of roughness on fluid flow have mainly considered a continuous phase whose behavior is different from a discontinuous phase, i.e., an oil slug. To explore the dynamic behavior of droplet motion across a rough channel, a direct numerical simulation of in a three-dimensional channel is performed. Three models have been considered: model A had a rough surface only on the bottom walls, model B on both the bottom and top walls, and model C on all walls. The results show that in contrast with common observations, roughness promotes droplet mobility in comparison with smooth walls. The presence of roughness results to an additional energy required to move the droplet, and the degree of confinement increases with the roughness; thus, the difficult of mobilization increases with the increase in roughness. Different roughness parameter effects have been investigated. The results have shown that the critical pressure increases with the increase in the pillar's height and decreases with the pillars spacing. The offset leads to a decrease in flow resistance for larger contact angles. We noted also that it is more difficult to mobilize a discontinuous phase in a neutral-wet surface condition. Furthermore, discontinuous pillars in the lateral direction led to much higher resistance. Through our comprehensive numerical study, we provide valuable insights into the impact of roughness in capillary channels. These findings can be used as guidelines for designing droplet flow on complex and rough surfaces, such as microfluidic devices, and hold significant relevance in the optimization of droplet control strategies in enhanced oil recovery methods.
Real-time spectral interferometry enables ultrafast acoustic detection
Authors: Liu Yusong , Ni Wenjun , Yang Liuyang , Huang Siyun , Liu Haoguang , Sun Yixiang , Xia Ran , Yao Yao , Yan Lisong , Luo Yiyang , Xu Zhilin , Xu Gang , Sun Qizhen , Tang Xiahui , Shum Perry Ping
Published: November 2023

Optical interferometry is a promising alternative for acoustic detection as it records the changes of interference patterns. Apart from interferometric sensor heads, readout systems also play a crucial role in sensing performance. Here, inspired by the soliton molecule vibrations in ultrafast lasers, we introduce an efficient real-time spectral interferometry (RSI) approach to read out the Fabry–Pérot interferometer (FPI) for acoustic detection. Broadband pulses, emitted from an ultrafast fiber laser, are launched into the FPI sensor. Pseudo dual-pulse molecule is constructed by virtue of the equivalent two-beam interference of the FPI and modulated by the diaphragm transducer. The acoustic driven “molecular vibration” conforms to the sound applied on the metal diaphragm. Hence, the acoustic signals can be directly recorded by the successive dual-pulse spectral interferograms, imaged as a spectral encoded “soundtrack.” We experimentally achieve the real-time characterization of both the audible and ultra sounds by retrieving the relative phase evolutions with a phase resolution of 37.6 mrad and preliminarily verifying the feasibility of the RSI in acoustic detection. This approach to wideband acoustic detection highlights an advanced application of ultrafast laser sources and paves an efficient way for interrogating the interferometric fiber sensors.
A heritable iron memory enables decision-making in
Escherichia coli
Authors: Bhattacharyya Souvik , Bhattarai Nabin , Pfannenstiel Dylan M. , Wilkins Brady , Singh Abhyudai , Harshey Rasika M.
Published: November 2023

The importance of memory in bacterial decision-making is relatively unexplored. We show here that a prior experience of swarming is remembered when
Escherichia coli
encounters a new surface, improving its future swarming efficiency. We conducted >10,000 single-cell swarm assays to discover that cells store memory in the form of cellular iron levels. This “iron” memory preexists in planktonic cells, but the act of swarming reinforces it. A cell with low iron initiates swarming early and is a better swarmer, while the opposite is true for a cell with high iron. The swarming potential of a mother cell, which tracks with its iron memory, is passed down to its fourth-generation daughter cells. This memory is naturally lost by the seventh generation, but artificially manipulating iron levels allows it to persist much longer. A mathematical model with a time-delay component faithfully recreates the observed dynamic interconversions between different swarming potentials. We demonstrate that cellular iron levels also track with biofilm formation and antibiotic tolerance, suggesting that iron memory may impact other physiologies.
Exploring homology of fields in translation
Authors: Mengyuan Zhou
Published: November 2023

The translation and reception of contemporary Chinese literature into Portuguese have gained prominence recently but have not received much scholarly attention. This study employs Pierre Bourdieu’s concept of homology to analyze the relationship between translation and various related fields and their impact on translating Chinese contemporary literature in Brazil and Portugal from 2000 to 2022. It highlights how these fields’ interconnectedness has both facilitated and hindered translation practices. The research explores the notion of fields and homology and examines the translation production process, focusing on how the translation field interacts with its academic, educational, and political counterparts. Using the translation of contemporary Chinese literature into Portuguese as a case study, the article suggests that the structural similarity among these fields significantly affects how Chinese literature is translated and received, influencing the choice of works, translation methods, and publishing priorities. Through an extensive analysis, the study bridges Bourdieu’s homology concept with practical scenarios, enhancing the discourse in translation studies and Chinese literature, particularly in the Portuguese context.
Highly Anisotropic Magnetism and Nearly Isotropic Magnetocaloric Effect in Mn3Sn2 Single Crystals
Authors: Bai Jianli , Dong Qingxin , Zhang Libo , Liu Qiaoyu , Cheng Jingwen , Liu Pinyu , Li Cundong , Sun Yingrui , Huang Yu , Ren Zhian , Chen Genfu
Published: November 2023

Mn3Sn2 has been proposed as an ideal material for magnetic refrigeration. It undergoes two successive ferromagnetic transitions (T
C1 = 262 K and T
C2 = 227 K) and one antiferromagnetic transition (T
N = 192 K). Herein we report, for the first time, the preparation of single crystals of Mn3Sn2 from Bi flux. The resultant anisotropic magnetic properties and magnetocaloric effect are investigated along the three principal crystallographic directions of the crystal. Significant anisotropy of magnetic susceptibility and multiple field-induced metamagnetic transitions were found at low fields, whereas the magnetocaloric effect was found to be almost isotropic and larger than that of the polycrystalline one. The maximum magnetic entropy change amounts to −ΔS
M = 4.01 J⋅kg−1⋅K−1 near T
C1 under a magnetic field change of μ
0ΔH = 5 T along the c-axis, with the corresponding refrigerant capacity of 1750 mJ⋅cm−3. Combined with a much wider cooling temperature span (∼ 80 K), our results demonstrate Mn3Sn2 single crystal to be an attractive candidate working material for active magnetic refrigeration at low temperatures.
Twin-Capture Rydberg State Excitation Enhanced with Few-Cycle Laser Pulses
Authors: Zhao 赵 Jing 晶 , Liu 刘 Jinlei 金磊 , Wang 王 Xiaowei 小伟 , Zhao 赵 Zengxiu 增秀
Published: November 2023

Quantum excitation is usually regarded as a transient process occurring instantaneously, leaving the underlying physics shrouded in mystery. Recent research shows that Rydberg-state excitation with ultrashort laser pulses can be investigated and manipulated with state-of-the-art few-cycle pulses. We theoretically find that the efficiency of Rydberg state excitation can be enhanced with a short laser pulse and modulated by varying the laser intensities. We also uncover new facets of the excitation dynamics, including the launching of an electron wave packet through strong-field ionization, the re-entry of the electron into the atomic potential and the crucial step where the electron makes a U-turn, resulting in twin captures into Rydberg orbitals. By tuning the laser intensity, we show that the excitation of the Rydberg state can be coherently controlled on a sub-optical-cycle timescale. Our work paves the way toward ultrafast control and coherent manipulation of Rydberg states, thus benefiting Rydberg-state-based quantum technology.
Total light bending in non-asymptotically flat black hole spacetimes
Authors: Sánchez Flavio C , Roque Armando A , Rodríguez Benito , Chagoya Javier
Published: November 2023

The gravitational deflection of light is a critical test of modified theories of gravity. A few years ago, Gibbons and Werner introduced a definition of the deflection angle based on the Gauss–Bonnet theorem. In more recent years, Arakida proposed a related idea for defining the deflection angle in non-asymptotically flat spacetimes. We revisit this idea and use it to compute the angular difference in the Kottler geometry and a non-asymptotically flat solution in Horndeski gravity. Our analytic and numerical calculations show that a triangular array of laser beams can be designed so that the proposed definition of the deflection angle is sensitive to different sources of curvature. Moreover, we find that near the photon sphere, the deflection angle in the Horndeski solution is similar to its Schwarzschild counterpart, and we confirm that the shadows seen by a static observer are identical.
Augmented reality technology in teaching about physics: a systematic review of opportunities and challenges
Authors: Vidak Andrej , Movre Šapić Iva , Mešić Vanes , Gomzi Vjeran
Published: November 2023

The use of augmented reality (AR) allows for the integration of digital information onto our perception of the physical world. In this article, we present a comprehensive review of previously published literature on the implementation of AR in physics education, at the school and the university level. Our review includes an analysis of 96 papers from the Scopus and Eric databases, all of which were published between 1st January 2012 and 1st January 2023. We evaluated how AR has been used for facilitating learning about physics. Potential AR-based learning activities for different physics topics have been summarized and opportunities, as well as challenges associated with AR-based learning of physics have been reported. It has been shown that AR technologies may facilitate physics learning by providing complementary visualizations, optimizing cognitive load, allowing for haptic learning, reducing task completion time and promoting collaborative inquiry. The potential disadvantages of using AR in physics teaching are mainly related to the shortcomings of software and hardware technologies (e.g. camera freeze, visualization delay) and extraneous cognitive load (e.g. paying more attention to secondary details than to constructing target knowledge).
Interfacial molecular structure of phosphazene-based polymer electrolyte at the air-aqueous interface using sum frequency generation vibrational spectroscopy
Authors: Kaur Sarabjeet , Tomar Deepak , Chaudhary Monika , Rana Bhawna , Kaur Harsharan , Nigam Vineeta , Jena Kailash C
Published: November 2023

The change induced in the physicochemical properties of polymer while hosting ions provides a platform for studying its potential applications in electrochemical devices, water treatment plants, and materials engineering science. The ability to host ions is limited in very few polymers, which lack a detailed molecular-level understanding for showcasing the polymer-ion linkage behavior at the interfacial region. In the present manuscript, we have employed sum frequency generation (SFG) vibrational spectroscopy to investigate the interfacial structure of a new class phosphazene-based methoxyethoxyethoxyphosphazene (MEEP) polymer in the presence of lithium chloride salt at the air-aqueous interface. The interfacial aspects of the molecular system collected through SFG spectral signatures reveal enhanced water ordering and relative hydrogen bonding strength at the air-aqueous interface. The careful observation of the study finds a synchronous contribution of van der Waals and electrostatic forces in facilitating changes in the interfacial water structure that are susceptible to MEEP concentration in the presence of ions. The observation indicates that dilute MEEP concentrations support the role of electrostatic interaction, leading to an ordered water structure in proximity to diffused ions at the interfacial region. Conversely, higher MEEP concentrations promote the dominance of van der Waals interactions at the air-aqueous interface. Our study highlights the establishment of polymer electrolyte (PE) characteristics mediated by intermolecular interactions, as observed through the spectral signatures witnessed at the air-aqueous interface. The investigation illustrates the polymer-ion linkage adsorption effects at the interfacial region, which explains the macroscopic changes observed from the cyclic voltammetry studies. The fundamental findings from our studies can be helpful in the design and fine-tuning of better PE systems that can offer improved hydrophobic membranes and interface stability for use in electrochemical-based power sources.
Attention features selection oversampling technique (AFS-O) for rolling bearing fault diagnosis with class imbalance
Authors: Han Zhongze , Wang Haoran , Shen Chen , Song Xuewei , Cao Longchao , Yu Lianqing
Published: November 2023

When using data-driven methods for fault diagnosis of mechanical rotating components such as gears and bearings, there is a problem of class imbalance in the lifecycle data collected by sensors. The most commonly used method to address this issue is the synthetic minority over-sampling technique, which synthesizes samples in the feature space, but its blind synthesis may lead to redundant features in the synthetic samples. To avoid this deficiency, this paper proposes a feature-weighted oversampling method called AFS-O (Attention Features Selection Oversampling Technique). First, time–frequency domain features are extracted from the full lifecycle data of bearings to construct an initial subset of features, which serves the input to AFS. Then, AFS is then used to obtain the distribution of feature selection patterns and generate feature weights to determine the inclusion or exclusion of each feature, thereby constructing an optimal subset of features. Finally, the optimal feature subset is synthetically oversampled to achieve class-balanced data, which is then fed into a classifier. AFS-O is applied to the rolling bearing accelerated lifetime dataset from Xi’an Jiaotong University. Experimental results demonstrate that AFS-O outperforms other state-of-the-art synthetic oversampling algorithms in terms of Gmean,

F

2

score

, and Recall, confirming the effectiveness of the proposed method.
Multiple damage segmentation and extraction of wind turbine blades surface under complex background based on SKRT approach
Authors: Wang Mingqing , Zheng Yuqiao , Lang Qifa , Shi Chenglong , Liu Yuhang
Published: November 2023

Machine vision detection technology has been widely used in detecting wind turbine blade surface damage, but the complex background often has a significant impact on blade damage detection. Aiming at the complex background blade images caused by various natural background features, complex blade surface features, low contrast features, non-uniform illumination, weather conditions, and other factors, the work proposes an SKRT segmentation method based on K-means clustering and adaptive threshold fusion to segment and extract multiple damage features on the surface of wind turbine blades with complex backgrounds. Firstly, an single-scale retinex(SSR) algorithm is adopted to enhance the contrast between surface damage and image background in the research. Then the image is roughly segmented by K-means clustering to remove most of the background features, and the background mask is replaced with the peak of the remaining feature image pixels to solve the problem of wrong segmentation. Finally, making use of the adaptive threshold local segmentation method to accurately segment the blade surface damage. The experimental results show that the proposed SKRT segmentation method can significantly improve the segmentation accuracy of wind turbine blade surface damage with complex background, and the accuracy, intersection over union, and F-measure value are increased by 37.20%, 35.71%, and 28.69%, respectively. The method performs better robustness to multiple damage feature segmentation.
High-resolution turbofan intake flow characterization by automated stereoscopic-PIV in an industrial wind tunnel environment
Authors: Kempaiah Kushal U , Piovesan Tommaso , Zachos Pavlos K , Michaelis Dirk , Gebbink Roy , van Rooijen Bart , Prieto Daniel Gil , MacManus David , Sciacchitano Andrea , Sheaf Christopher
Published: November 2023

Unsteady inlet flow distortion can influence the stability and performance of any propulsion system, in particular for more novel, short and slim intakes of future aero-engine configurations. As such, the requirement for measurement methods able to provide high spatial resolution data is important to aid the understanding of these flow fields. This work presents flow field characterisations at a crossflow plane within a short aeroengine intake using stereoscopic particle image velocimetry (SPIV). A series of tests were conducted across a range of crosswind and high angle of attack conditions for a representative short and slim aspirated intake configuration at two operating points in terms of mass flow rate. The velocity maps were measured at a crossflow plane within the intake at an axial position L/D = 0.058 from where a fan is expected to be installed. The diameter of the measurement plane was 250 mm, and the final spatial resolution of the velocity fields had a vector pitch of 1.5 mm which is at least two orders of magnitude richer than conventional pressure-based distortion measurements. The work demonstrates the ability to perform robust non-intrusive flow measurements within modern intake systems in an industrial wind tunnel environment across a wide range of operating conditions; hence, it is suggested that SPIV can potentially become part of standard industrial testing. The results provide rich datasets that can notably improve our understanding of unsteady distortions and influence the design of novel, closely coupled engine-intake systems.
Numerical simulation of nanosecond laser drilling of 316L stainless steel: addition of laser focus and analysis of manufacturing process
Authors: Zhao Junliang , Li Chen , Wang Jing
Published: November 2023

A two-dimensional model of nanosecond laser drilling 316L stainless steel was established with the consideration of laser focus, which was indeed different from the original two-phase flow model without laser focus, especially in the temperature field, velocity field, surface morphology and hole depth. Simulation and experiment of drilling holes with different laser repetition frequencies (100 kHz, 50 kHz and 20 kHz) were carried out. The results show that manufacturing process could divide into three stages: high-efficiency phase, stabilization stage and low-efficiency phase. Meanwhile, the limited number of pulses at 100 kHz, 50 kHz and 20 kHz were obtained, and the values were approximately 289, 367 and 492, respectively. More, the values at 10 kHz and 200 kHz obtained by modeling were very close to those calculated by the fitted equation. All the research provides theoretical, simulation and experimental basis for designing and optimizing parameters on laser surface manufacturing.