bluuebunny/crossref_metadata_2025 huggingface dataset:
Interplay of chemotactic force, Péclet number, and dimensionality dictates the dynamics of auto-chemotactic chiral active droplets
Authors: Chan Chung Wing , Yang Zheng , Gan Zecheng , Zhang Rui
Published: July 2024

In living and synthetic active matter systems, the constituents can self-propel and interact with each other and with the environment through various physicochemical mechanisms. Among these mechanisms, chemotactic and auto-chemotactic effects are widely observed. The impact of (auto-)chemotactic effects on achiral active matter has been a recent research focus. However, the influence of these effects on chiral active matter remains elusive. Here, we develop a Brownian dynamics model coupled with a diffusion equation to examine the dynamics of auto-chemotactic chiral active droplets in both quasi-two-dimensional (2D) and three-dimensional (3D) systems. By quantifying the droplet trajectory as a function of the dimensionless Péclet number and chemotactic strength, our simulations well reproduce the curling and helical trajectories of nematic droplets in a surfactant-rich solution reported by Krüger et al. [Phys. Rev. Lett. 117, 048003 (2016)]. The modeled curling trajectory in 2D exhibits an emergent chirality, also consistent with the experiment. We further show that the geometry of the chiral droplet trajectories, characterized by the pitch and diameter, can be used to infer the velocities of the droplet. Interestingly, we find that, unlike the achiral case, the velocities of chiral active droplets show dimensionality dependence: its mean instantaneous velocity is higher in 3D than in 2D, whereas its mean migration velocity is lower in 3D than in 2D. Taken together, our particle-based simulations provide new insights into the dynamics of auto-chemotactic chiral active droplets, reveal the effects of dimensionality, and pave the way toward their applications, such as drug delivery, sensors, and micro-reactors.
Effects of H-doping in Y2Fe17 compounds on the structure, magnetic properties, and Mössbauer effect
Authors: Wu Wei , Wu Peng , Yang Shengyu , Wang Wenbiao , Tu Chengfa , Li Zhiwei , Wang Tao , Li Fashen , Qiao Liang
Published: July 2024

We introduce a novel water bath hydrogenation process designed to enhance the magnetic properties and hyperfine field of Y2Fe17. The core of this process lies in the successful preparation of a new compound Y2Fe17H3.5 by introducing hydrogen in a mild water bath environment, accomplished by a chemical reaction between calcium, Y2Fe17, and ammonium acetate solution at room temperature and pressure. After hydrogen doping, cell volume expansion increased from 778.511 to 795.383 Å3, and notably, lattice expansion is anisotropic. Furthermore, saturation magnetization is increased from 103 to 134.93 emu/g, Curie temperature is increased from 320 to 461 K, and the average hyperfine field is increased from 18 to 25 T. The improvement in magnetic properties is due to the increase in Fe–Fe distance, which according to the Bethe–Slater curve leads to stronger Fe–Fe exchange interactions and enhancing ferromagnetic interactions. This work not only proposes the novel rhombohedral Y2Fe17H3.5 with excellent magnetic properties, but also provides a new method for hydrogen doping in Y2Fe17 which lays the foundation of fundamental solid state physics for further research.
Combined acoustic metamaterial design based on multi-channel Fano resonance effect
Authors: Zhang Xinhao , Zhao Caiyou , Wang Ping , Chen Rong
Published: July 2024

In response to the increasing traffic noise problem, we designed a combined acoustic metamaterial (CAM) based on the multi-channel Fano resonance principle. By utilizing the Fano resonance coupling between the acoustic spiral structure and the hollow structure, efficient sound insulation under effective ventilation conditions is achieved. Simulation results of acoustic transmission loss show that the acoustic transmission loss of CAM is more than 13 dB in the frequency band of 520–989 Hz. The broadband sound insulation characteristic can block the oblique angle incident sound waves from different angles. Simulation results of the elastic strain energy and acoustic pressure field validate the sound insulation mechanism of the Fano resonance of the combined acoustic metamaterial. The experimental results in the impedance tube generally agree with the simulation results. To explore the possibility of wider engineering applications of CAM, we propose a combined CAM and CAM0.7 structure. The results show that a series structure of acoustic metamaterials can be selected to further realize broadband sound insulation within 500–1574 Hz.
Photonic next-generation reservoir computer based on distributed feedback in optical fiber
Authors: Cox Nicholas , Murray Joseph , Hart Joseph , Redding Brandon
Published: July 2024

Reservoir computing (RC) is a machine learning paradigm that excels at dynamical systems analysis. Photonic RCs, which perform implicit computation through optical interactions, have attracted increasing attention due to their potential for low latency predictions. However, most existing photonic RCs rely on a nonlinear physical cavity to implement system memory, limiting control over the memory structure and requiring long warm-up times to eliminate transients. In this work, we resolve these issues by demonstrating a photonic next-generation reservoir computer (NG-RC) using a fiber optic platform. Our photonic NG-RC eliminates the need for a cavity by generating feature vectors directly from nonlinear combinations of the input data with varying delays. Our approach uses Rayleigh backscattering to produce output feature vectors by an unconventional nonlinearity resulting from coherent, interferometric mixing followed by a quadratic readout. Performing linear optimization on these feature vectors, our photonic NG-RC demonstrates state-of-the-art performance for the observer (cross-prediction) task applied to the Rössler, Lorenz, and Kuramoto–Sivashinsky systems. In contrast to digital NG-RC implementations, we show that it is possible to scale to high-dimensional systems while maintaining low latency and low power consumption.
Effects of windbreak types on aerodynamics of high-speed trains traversing from flat ground to semi-cutting and semi-embankment under crosswinds
Authors: Zhao Lun , Yang Wei-Chao , Liu Yi-Kang , Deng E
Published: July 2024

Under the operation of strong crosswinds, the aerodynamic performance of high-speed trains (HSTs) will be seriously deteriorated when the transition section of flat ground and semi-cutting and semi-embankment (FGSCSE) is traversed, and the setting of windbreaks will help to slow down the impact of strong crosswinds on the trains. In this study, a three-dimensional coupled computational fluid dynamics numerical model to assess the aerodynamic performance of train–windbreak–FGSCSE–air system is developed. A comparative assessment is carried out to identify the variations in aerodynamic performance on the train carriage: no windbreak (NW), 50% ventilation windbreak (VW), and solid windbreak (SW), and the reasons for these variations are elucidated by examining the flow field structure's evolution. Furthermore, the operational safety of the train is discussed based on the indicator of wheel unloading ratio (fΔQ). Across the three distinct conditions, significant abrupt changes in aerodynamic load coefficients (ALCs) and the shedding of vortex structures are experienced by HSTs traversing the FGSCSE transition sections. Compared to the VW condition, the NW and SW conditions result in a greater number of shedding vortices on the leeward side and the tail of the train, and the VW condition results in the smallest magnitude of ALCs fluctuation. The power spectral density peak values of the aerodynamic loads follow the order: SW > NW > VW. Upon the train fully enters the subsequent operational environment, the VW condition has the smallest standard deviation of these coefficients. The standard deviations of CFy, CFz, CMx, CMy, and CMz for the head train in the VW condition are only 57.17% (46.81%), 55.85% (54.15%), 72.74% (34.62%), 57.99% (51.92%), and 44.60% (43.82%) of the corresponding values in the NW (SW) condition, respectively. In the NW, VW, and SW conditions, the fΔQ exceeds 0.9 when the wind speeds reach 30, 40, and 35 m/s, respectively. The windbreak with a ventilation rate of 30% performs the best, providing the most effective safety and stability for train operation.
Computation of three-dimensional incompressible flows using high-order weighted essentially non-oscillatory finite-difference lattice Boltzmann method
Authors: Hejranfar Kazem , Abotalebi Mohammad
Published: July 2024

In the present work, an accurate and robust solution methodology based on the high-order weighted essentially non-oscillatory (WENO) finite-difference lattice Boltzmann method (LBM) in the three-dimensional generalized curvilinear coordinates is presented and applied for simulating the three-dimensional incompressible flows over complicated configurations with curved boundaries. Here, the incompressible form of the lattice Boltzmann equation in three dimensions is considered and the discretization of the spatial derivative terms is performed with the fifth-order WENO finite-difference method and the temporal derivative term is discretized with the fourth-order Runge–Kutta scheme to ensure the accuracy and stability of the solution method for both the steady and unsteady problems. The three-dimensional lattice Boltzmann equation applied here is based on a nineteen discrete velocity model for transforming the microscopic properties to the macroscopic ones. To assess the accuracy and robustness of the present three-dimensional high-order finite-difference LBM solver, different incompressible flow benchmarks and practical test cases are studied that are the cavity flow, the Beltrami flow, the flow in the curved ducts of rectangular cross sections, and the flow over a sphere for different flow conditions. The decay of the homogeneous isotropic turbulence is also computed to examine the suitability of the present solution method to be applied as the direct numerical simulation of turbulent flows. It is demonstrated that the solution methodology presented based on the high-order WENO finite-difference LBM in the three-dimensional generalized curvilinear coordinate can be used for accurately and effectively computing the three-dimensional practical incompressible flow problems.
Exploring kinematic stability of vortex structures: A topological approach to fluid flow around staggered square cylinders
Authors: Kumar A. Deepak , Sourav B. Kumar , Sen C. Subhankar
Published: July 2024

In this study, a detailed fluid dynamics analysis is conducted around two identical square cylinders in a staggered configuration at a Reynolds number (Re) of 40, using a stabilized finite-element method to investigate the kinematic stability of vortex structures. By varying the horizontal spacing (S/D) between 2 and 30 and examining transverse gaps (T/D) of 0.25, 0.8, and 1.25, the research uncovers significant flow behavior variations from the tandem configuration, highlighting complex fluid-structure interactions. The presence of “separation bubbles” at lower S/D values across all T/D ratios indicates the dynamic impact of the upstream cylinder's proximity on the flow field, particularly on the stagnation points of the downstream cylinder. Through a comprehensive topological analysis, the study identifies various flow regimes and topological bifurcations, revealing transitions between stable states that maintain the number of critical points constant, and the kinematic stability of these vortical structures is established by the critical point theory. The effect of cylinder configurations and diverse flow structures on fluid loading is also analyzed by examining surface pressure coefficients. The asymmetry present in the cylinder configuration is manifested through the asymmetric values of lift coefficients.
Prospects of silicide contacts for silicon quantum electronic devices
Authors: Tsoukalas K. , Schupp F. , Sommer L. , Bouquet I. , Mergenthaler M. , Paredes S. , Vico Triviño N. , Luisier M. , Salis G. , Harvey-Collard P. , Zumbühl D. , Fuhrer A.
Published: July 2024

Metal contacts in semiconductor quantum electronic devices can offer advantages over doped contacts, primarily due to their reduced fabrication complexity and lower temperature requirements during processing. Some metals can also facilitate ambipolar device operation or form superconducting contacts. Furthermore, a sharp metal–semiconductor interface allows for contact placement in close proximity to the active device area avoiding damage caused by dopant implantation. However, in the case of gate-defined quantum dots in intrinsic silicon, the formation of a Schottky barrier at the silicon–metal interface can lead to large, nonlinear contact resistances at cryogenic temperatures. We investigate this issue by examining hole transport through metal oxide-semiconductor transistors with platinum silicide contacts on intrinsic silicon substrates. We extract the contact and channel resistances as a function of temperature and improve the cryogenic conductance of the device by more than an order of magnitude by implementing meander-shaped contacts. In addition, we observe signatures of enhanced transport through localized defect states, which we attribute to platinum clusters in the depletion region of the Schottky contacts that form during the silicidation process. These results showcase the prospects of silicide contacts in the context of cryogenic quantum devices and address associated challenges.
Nonlinear dynamics of planetary roller screw mechanism
Authors: Mo Shuai , Wu Shengyang , Huang Xuan , Liu Wenbin , Zhou Yuansheng , Zhang Jielu , Zhang Wei
Published: July 2024

The synchronous meshing of the gear pair and the screw pair is a typical feature of the planetary roller screw mechanism. In order to fully derive and analyze the nonlinear dynamic characteristics of the system, this paper creatively incorporates the time-varying meshing stiffness of gear pair and the comprehensive transmission error into the research content. Combined with the thread contact force and friction force between the roller and the screw and between the roller and the nut, the nonlinear dynamic model of the planetary roller screw mechanism considering the meshing excitation of the gear pair is established. According to the time domain diagram, frequency domain diagram, phase plane diagram, Poincaré section diagram, three-dimensional spectrum diagram, and spatial phase diagram, the nonlinear behavior of the system is described in detail, and the bifurcation evolution process of the system under the excitation frequency parameters of the external load is revealed. In addition, based on the theory of multi-scale method and considering the variables such as meshing stiffness, meshing damping, and load fluctuation, the stability equation of the primary resonance of the system is derived. The analysis of the stability of the system under different working conditions shows that the parameters are selected within a reasonable range, which effectively reduces the primary common amplitude value and enhances the overall stability of the system. The research content improves the previous system dynamics modeling method and provides a theoretical basis for the nonlinear dynamics modeling method and parameter optimization design of the planetary roller screw mechanism.
Thermoelectric response in zigzag chains: Impact of irradiation-induced conformational changes
Authors: Ganguly Sudin , Mondal Kallol , Maiti Santanu K.
Published: July 2024

This study explores the enhancement of thermoelectric response in a zigzag chain through irradiation with arbitrarily polarized light. The irradiation induces changes in hopping strengths, creating an asymmetric transmission profile around the Fermi energy, which is a crucial factor for achieving a higher figure of merit (FOM). Specific light configurations result in an FOM exceeding unity. We employ the Floquet–Bloch ansatz and minimal coupling scheme to model the irradiation effect, with transport properties evaluated using Green’s function technique within the Landauer–Büttiker formalism. The investigation covers electrical conductance, thermopower, and thermal conductance due to electrons and phonons. Our research deepens understanding and opens avenues for tailoring nanostructures to fine-tune thermoelectric properties, advancing highly efficient energy conversion devices exploiting irradiation effects.
Development of a machine learning interatomic potential for exploring pressure-dependent kinetics of phase transitions in germanium
Authors: Fantasia A. , Rovaris F. , Abou El Kheir O. , Marzegalli A. , Lanzoni D. , Pessina L. , Xiao P. , Zhou C. , Li L. , Henkelman G. , Scalise E. , Montalenti F.
Published: July 2024

We introduce a data-driven potential aimed at the investigation of pressure-dependent phase transitions in bulk germanium, including the estimate of kinetic barriers. This is achieved by suitably building a database including several configurations along minimum energy paths, as computed using the solid-state nudged elastic band method. After training the model based on density functional theory (DFT)-computed energies, forces, and stresses, we provide validation and rigorously test the potential on unexplored paths. The resulting agreement with the DFT calculations is remarkable in a wide range of pressures. The potential is exploited in large-scale isothermal-isobaric simulations, displaying local nucleation in the R8 to β-Sn pressure-induced phase transformation, taken here as an illustrative example.
Modulate the work function of MXene in MXene/InGaN heterojunction for visible light photodetector
Authors: Hao Ququ , Chen Liang , Wang Wenliang , Li Guoqiang
Published: July 2024

MXene/InGaN heterojunction photodetectors with simple structure and superior optoelectronic performance are considered a viable option for optical communication. However, the integration of MXene with InGaN faces the problem of a relatively low Schottky barrier, leading to electron backflow, which hinders the separation of carriers and limits the photoresponse of photodetectors. Herein, high-performance MXene/InGaN heterojunction photodetectors were fabricated, and the work function of Ti3C2TX was modulated to explore its effect on the performance of the photodetectors. The ascorbic acid treatment increased the work function of MXene from 4.20 to 4.34 eV, enhancing the Schottky barrier height of the heterojunction from 0.56 to 0.70 eV. The devices exhibit excellent photoresponse performances, such as a responsivity of 0.133 A W−1 and a specific detectivity of 2.81 × 1011 Jones at −1 V bias, as well as a short rise/decay time of 37.49/110 μs at 0 V bias. Additionally, the photodetectors achieve high stability that can maintain over 95% of the initial value after 3 months. This work indicates the potential for utilizing tunable MXene work function to construct high-performance optoelectronic devices for visible light applications.
Excess noise and thermoelectric effect in magnetron-sputtered VO2 thin films
Authors: Gunes Ozan , Onumonu Onyebuchi I. , Gholizadeh A. Baset , Zhang Chunzi , Yang Qiaoqin , Wen Shi-Jie , Curry Richard J. , Johanson Robert E. , Kasap Safa O.
Published: July 2024

This work presents the excess noise and thermoelectric (Seebeck) measurements on polycrystalline vanadium dioxide (VO2) thin films. Noise spectral power density (SPD) of current fluctuations in the semiconducting (SC) phase had a typical flicker noise (f−γ) characteristic with an average slope parameter γ of 1.13. Normalized SPD (Sn) values obtained in the SC-phase indicate that the noise originates in the bulk of the film. On the contrary, in the metallic (M)-phase, γ values were greater than unity, and the observed Sn values indicated that the origin of the noise is most likely from the contacts or surface rather than the bulk. A general decrease was observed in Sn by a factor of 4–5 from the SC- to M-phase. Moreover, Sn in the SC-phase showed no temperature dependence. An interpretation based on the number of charge carrier fluctuations in Hooge's model led to an unrealistically high Hooge parameter and had to be ruled out. We propose that the fluctuations are related to the mobility fluctuations of carriers arising primarily from grain-boundary scattering which explains the observed characteristics well. The Seebeck coefficients (S) obtained under both heating and cooling schedules showed the n-type nature of magnetron-sputtered VO2 films in the SC-phase. Differently, in the M-phase, the S value was positive. The S values obtained from the cooling schedule signified the low percolation threshold of the metal-to-insulator transition already demonstrated for VO2 thin films grown on r-cut sapphire using the Efros–Shklovskii percolation model.
Scalable synchronization cluster in networked chaotic oscillators
Authors: Fan Huawei , Wang Yafeng , Du Yao , Qiu Haibo , Wang Xingang
Published: July 2024

Cluster synchronization in synthetic networks of coupled chaotic oscillators is investigated. It is found that despite the asymmetric nature of the network structure, a subset of the oscillators can be synchronized as a cluster while the other oscillators remain desynchronized. Interestingly, with the increase in the coupling strength, the cluster is expanding gradually by recruiting the desynchronized oscillators one by one. This new synchronization phenomenon, which is named “scalable synchronization cluster,” is explored theoretically by the method of eigenvector-based analysis, and it is revealed that the scalability of the cluster is attributed to the unique feature of the eigenvectors of the network coupling matrix. The transient dynamics of the cluster in response to random perturbations are also studied, and it is shown that in restoring to the synchronization state, oscillators inside the cluster are stabilized in sequence, illustrating again the hierarchy of the oscillators. The findings shed new light on the collective behaviors of networked chaotic oscillators and are helpful for the design of real-world networks where scalable synchronization clusters are concerned.
Nanopipette dynamic microscopy unveils nano coffee ring
Authors: Zhang Deyi , Shao Yi , Zhou Jiayi , Zhan Qiangwei , Wen Ziyang , Mao Sheng , Wei Jingjing , Qi Limin , Shao Yuanhua , Wang Huan
Published: July 2024

Liquid-phase electron microscopy (LP-EM) imaging has revolutionized our understanding of nanosynthesis and assembly. However, the current closed geometry limits its application for open systems. The ubiquitous physical process of the coffee-ring phenomenon that underpins materials and engineering science remains elusive at the nanoscale due to the lack of experimental tools. We introduce a quartz nanopipette liquid cell with a tunable dimension that requires only standard microscopes. Depending on the imaging condition, the open geometry of the nanopipette allows the imaging of evaporation-induced pattern formation, but it can also function as an ordinary closed-geometry liquid cell where evaporation is negligible despite the nano opening. The nano coffee-ring phenomenon was observed by tracking individual nanoparticles in an evaporating nanodroplet created from a thin liquid film by interfacial instability. Nanoflows drive the assembly and disruption of a ring pattern with the absence of particle–particle correlations. With surface effects, nanoflows override thermal fluctuations at tens of nanometers, in which nanoparticles displayed a “drunken man trajectory” and performed work at a value much smaller than
k
B
T
.
Immigrants’ attitudes towards varieties of American English
Authors: Lee Jeongyi , Huh Keun
Published: July 2024

Native speakers of English commonly perceive some social variants of their language to be more prestigious than
others. It is less clear, however, whether nonnative English speakers from immigrant communities come to internalize similar
language stereotypes. The present study analysed, through a language attitude survey, a total of 40 Korean American college
students’ reactions to tape-recorded samples of five socially stratified varieties of English commonly heard in the U.S. Results
indicated that Korean American college students perceived a Standard American English (SAE) typical of broadcast English in the
U.S. most favourably. Nonstandard varieties (regional and ethnic dialects), especially African American English, were judged as
less favourable. SAE and its speaker was associated with positive qualities on rating scales, while nonstandard guises were rated
less favourably on the same characteristics. This study provides a greater understanding of how different English varieties are
perceived by an immigrant community in the U.S. and invites future studies of English language attitudes in other minority
communities.
“Yet ar ye not lyche, for thu art a fals strumpet”
Authors: Timofeeva Olga , Kahlas-Tarkka Leena
Published: July 2024

In Late Middle English, the system of second-person pronouns with singular referents is characterised by
retractable choices based on the interactional status of interlocutors. This system has until recently been documented mostly in
studies based on poetic texts, such as the Canterbury Tales by Chaucer, and, to a lesser extent, private
correspondence and mystery plays. We use the Book of Margery Kempe as a primary source and offer the perspective
of a middle-class female author from early-fifteenth-century Norfolk. Conventional politeness of Margery Kempe requires the
default use of ye/you/your forms, especially when addressees are unfamiliar, older or socially superior, but also
in situations of mutual acceptance and deference. Thou/thee/thine forms, on the other hand, indicate social or
intellectual superiority as well as, at the interactional level, condescension, contempt, annoyance, defiance and abuse. Their
use, therefore, is typically marked.
重慶方言句末語氣詞的意義功能及結構
Authors: Tang Li , Hsu Yu-Yin
Published: July 2024

抽象的

本文分析重慶方言中七個句末語氣詞各自獨特的核心意義和功能並論證它們的結構位置。我們認為重慶方言的句末語氣詞可以分為三大類，符合Rizzi
(1997)與Paul
(2014)的CP分裂假說，它們在結構上分別在不同功能層中佔據中心語位置，其中重慶話的「lao」和普通話句末語氣詞「了」用法相同且佔據相同的位置，標示句子的限定性。「mai」、「ha」、「suo」三個疑問語氣詞標示疑問句，選擇陳述句為補足語構成是非問句，作為定義句子類型的Force中心語；但這三個疑問語氣詞分別表達命題和說話人預設之間不同的關聯。對於語法文獻中較少討論、與語篇相關的三個篇章語氣詞本文中也特別一併分析它們的語義及結構限制。本文主張重慶方言中篇章語氣詞在結構上受句法限制較小，因此可以運用在不同句子類型中，但語氣詞各有其核心語義：「haPRAG」用來緩和語氣，「sa」表示確認，「dema」是提示對話雙方的共知背景信息。重慶方言的考察對於語法本體研究中較少討論的篇章語氣詞提供了豐富有趣的資料。本研究的結果為CP分裂假說提供了跨語言的一致性的支持。此外，本文對不同類型語氣詞的核心語義的判定也可為未來研究漢語其他方言之間的區別與共性，或是對其他同樣有豐富句末語氣詞的語言研究及跨語言對比研究提供一定的基礎。
A novel STING variant triggers endothelial toxicity and SAVI disease
Authors: Valeri Erika , Breggion Sara , Barzaghi Federica , Abou Alezz Monah , Crivicich Giovanni , Pagani Isabel , Forneris Federico , Sartirana Claudia , Costantini Matteo , Costi Stefania , Marino Achille , Chiarotto Eleonora , Colavito Davide , Cimaz Rolando , Merelli Ivan , Vicenzi Elisa , Aiuti Alessandro , Kajaste-Rudnitski Anna
Published: July 2024

Gain-of-function mutations in STING cause STING-associated vasculopathy with onset in infancy (SAVI) characterized by early-onset systemic inflammation, skin vasculopathy, and interstitial lung disease. Here, we report and characterize a novel STING variant (F269S) identified in a SAVI patient. Single-cell transcriptomics of patient bone marrow revealed spontaneous activation of interferon (IFN) and inflammatory pathways across cell types and a striking prevalence of circulating naïve T cells was observed. Inducible STING F269S expression conferred enhanced signaling through ligand-independent translocation of the protein to the Golgi, protecting cells from viral infections but preventing their efficient immune priming. Additionally, endothelial cell activation was promoted and further exacerbated by cytokine secretion by SAVI immune cells, resulting in inflammation and endothelial damage. Our findings identify STING F269S mutation as a novel pathogenic variant causing SAVI, highlight the importance of the crosstalk between endothelial and immune cells in the context of lung disease, and contribute to a better understanding of how aberrant STING activation can cause pathology.
Note on black holes with kilometer-scale ultraviolet regulators
Authors: Boos Jens , Carone Christopher D
Published: July 2024

Regular black hole metrics involve a universal, mass-independent regulator that can be up to

O

(
700

km
)

while remaining consistent with terrestrial tests of Newtonian gravity and astrophysical tests of general relativistic orbits. However, for such large values of the regulator scale, the metric describes a compact, astrophysical-mass object with no horizon rather than a black hole. We note that allowing the regulator to have a nontrivial mass dependence preserves the horizon, while allowing large, percent-level effects in black hole observables. By considering the deflection angle of light and the black hole shadow, we demonstrate this possibility explicitly.
Cramér-Rao lower bounds on parameter estimation for a circular binary of supermassive black holes in gravitational wave observations using pulsar timing array
Authors: Duan Qing-Qing , Liu Jin , Kang Zhi-Wei
Published: July 2024

Pulsar timing arrays (PTAs) are effective in detecting low-frequency gravitational waves (GWs), especially in circular binary systems of supermassive black holes. To evaluate the effectiveness and accuracy of PTAs in searching for GW parameter estimation, we use the Cramer-Rao lower bound to estimate the parameters of the Virgo source under various search conditions, including both evolving and non-evolving scenarios, as well as Earth and pulsar term searches, and only Earth term searches. The results show that the estimation accuracy of the inclination angle and GW strain is lower in the evolving condition than in the non-evolving condition because the two parameters participate in the evolving process. In addition, we find that the parameters estimable relates to signal-to-noise ratio, which is beneficial for reducing the dimensionality in the search process. In summary, our method serves as a reference for exploring lower parameter limits under different conditions and assists in assessing the optimization of parameter estimation in GW detection algorithms. This helps lay the theoretical foundation for advances in the field of GWs and the optimization of PTAs.
Indirect measurement of atomic magneto-optical rotation via Hilbert transform
Authors: Briscoe Jack D , Pizzey Danielle , Wrathmall Steven A , Hughes Ifan G
Published: July 2024

The Kramers–Kronig relations are a pivotal foundation of linear optics and atomic physics, embedding a physical connection between the real and imaginary components of any causal response function. A mathematically equivalent, but simpler, approach instead utilises the Hilbert transform. In a previous study, the Hilbert transform was applied to absorption spectra in order to infer the sole refractive index of an atomic medium in the absence of an external magnetic field. The presence of a magnetic field causes the medium to become birefringent and dichroic, and therefore it is instead characterised by two refractive indices. In this study, we apply the same Hilbert transform technique to independently measure both refractive indices of a birefringent atomic medium, leading to an indirect measurement of atomic magneto-optical rotation. Key to this measurement is the insight that inputting specific light polarisations into an atomic medium induces absorption associated with only one of the refractive indices. We show this is true in two configurations, commonly referred to in literature as the Faraday and Voigt geometries, which differ by the magnetic field orientation with respect to the light wavevector. For both cases, we measure the two refractive indices independently for a Rb thermal vapour in a

0.6

T

magnetic field, finding excellent agreement with theory. This study further emphasises the application of the Hilbert transform to the field of quantum and atomic optics in the linear regime.
The electron affinity of rubidium: a state selective measurement
Authors: Ringvall-Moberg Annie , Nichols Miranda , Navarro Navarrete José E , Bērziņš Uldis , D’mello Viola C , Karls Julia , Lu Di , Peña Rodríguez Yazareth , Poulose Rachel , Morales Rodríguez Andrea , Ravi Keerthana , Ramachandran Meera , Zhaunerchyk Vitali , Hanstorp Dag , Leimbach David
Published: July 2024

Negative ions, which are formed when an electron is attached to a neutral system, are unique quantum systems. The lack of a long-range Coulomb force causes the inter-electronic interactions to become relatively more important. As a consequence, the independent particle model, which adequately describes atomic structure under normal conditions, breaks down. The alkali negative ions, with a closed valence s-shell, are among the simplest anionic systems. Hence, they can favorably be used to benchmark atomic theory. In this work, we have determined the electron affinity of 85Rb by measuring the relative partial photodetachment cross section of the negative ion, leaving the residual atom in the 5p

2

P

3
/
2

excited state. Resonance ionization spectroscopy allows for state selectivity and the ability to measure the Wigner s-wave threshold onset of the photodetachment process. The electron affinity of 85Rb was determined to be 485.887(6) meV.
Fatigue life prediction for high-speed railway bridges by reconstructing monitoring-based dynamic stress
Authors: Wei Yun-Tao , Yi Ting-Hua , Yang Dong-Hui , Li Hong-Nan , Liu Hua
Published: July 2024

Bridge responses that are excited by high-speed trains have the characteristics of high amplitude, high cycle, and large dynamic effects, which greatly affect the fatigue bearing capacity of affected bridges. To achieve reliable analysis of the fatigue performance of high-speed railway bridges, this study developed a bridge fatigue life prediction method based on the reconstruction of the train-induced dynamic stress time history. First, the equations for solving the static stress time history under influence line virtual loading are derived, and then the dynamic stress time history reconstruction method based on two types of dynamic correction factors is proposed. The statistical characteristics of the train loads and dynamic correction factors are fit according to monitoring data, and bridge fatigue life prediction is realized by use of the reliability theory. Finally, the applicability and effectiveness of the proposed method are verified by using a train-bridge interaction model and monitoring data from a long-span high-speed railway bridge. The results show that the proposed method can greatly improve the accuracy of fatigue performance analysis and can effectively predict the fatigue life of high-speed railway bridges under complex loads. These results can provide an important reference for fatigue evaluation of high-speed railway bridges.
Model predictive path tracking control of intelligent vehicles based on dual-stage disturbance observer under multi-channel disturbances
Authors: Guo Lie , Guo Pengyuan , Guan Longxin , Ma Hui
Published: July 2024

Parameter fluctuations, unmodeled dynamics, speed variation, steering actuator faults, and other multi-channel uncertain disturbances are the key challenges faced by the path tracking control of intelligent vehicles, which will affect the accuracy and stability of the path tracking. Therefore, a model predictive control (MPC) method based on a dual-stage disturbance observer (DDOB) is proposed in this paper. First, a tracking error dynamics model considering multi-channel uncertain disturbances is constructed, based on which a model predictive controller is designed to obtain the nominal front wheel steering angle by the Karush–Kuhn–Tucker (KKT) condition. Furthermore, the DDOB is designed to enable real-time estimation of the system disturbances, and then the estimated disturbances are used as the compensation for the nominal front wheel steering angle, which establishes the MPC control law with parallel compensation of the DDOB. Finally, the error boundedness of the DDOB and the global stability of the model predictive controller are analyzed. The effectiveness and superiority of the proposed algorithm are verified through Carsim–Simulink simulation and hardware-in-the-loop experiments.
Measurement of sand particle motion speed in multiphase wind-sand flow based on piezoelectric ceramic sensors
Authors: Pu Ou , Yuan Boqiu , Li Zhengnong , Chen Zheng , Liang Yong , Lin Xiqiao , Tan Jihui , Li Zhen
Published: July 2024

Utilizing Pb(ZrTi)O3-5 A piezoelectric ceramic (hereafter referred to as PZT-5 A) as sensors, we studied the movement speed of sand particles in multiphase wind-sand flows. We developed a mathematical model that effectively links the impact force of sand grains with the output voltage of PZT-5 A, incorporating factors such as the piezoelectric coefficient and sand particle characteristics. Additionally, we proposed a new method to accurately determine the elastic recovery coefficient of sand particles using PZT-5A sensor measurements and experimental setups, which is significant for the field of material science. Wind tunnel experiments revealed that at heights ranging from 0.1 to 1.0 m, sand particle speeds range from 52.8% to 91.4% of wind speeds. As wind speed increases to 15 m s−1, sand particle speed nears 91.4% of wind speed. Yet, at a constant wind speed, sand speed drops as sediment discharge rises. This research offers fresh insights into sand particle dynamics in wind-sand contexts.
Depth localization of subsurface defects by optical dark-field confocal microscopy
Authors: Liu Jian , Jiang Yong , Wang Ziyi , Zou Chongliang , Liu Chenguang
Published: July 2024

Subsurface defects (SSD) in optical components pose a significant challenge for enhancing the power density of high-energy laser devices. This study investigated the issue of systematic deviation between the measured and actual depths of SSD when employing optical dark-field confocal microscopy for three-dimensional measurements, which is attributed to refractive index disparities between the sample and the observation environment. This paper introduces geometric and diffraction optical models for correcting errors in the SSD depth, along with a calculation method for determining the correction coefficient. By comparing the experimental data and model simulations, a linear relationship between the measured and actual depths was identified with linearity errors below 2.5% and a minimum of 0.67%. The correction coefficients derived from the optical diffraction model are in good agreement with those obtained experimentally. These findings offer valuable insights for calculating SSD depth correction coefficients across various scenarios and requirements to ensure precise measurements.
Research on GNSS-IR soil moisture retrieval based on random forest algorithm
Authors: Zheng Naiquan , Chai Hongzhou , Wang Zhihao , Pu Dongdong , Zhang Qiankun
Published: July 2024

Soil moisture (SM) retrieval is of great significance in climate, agriculture, ecology, hydrology, and natural disaster monitoring, and it is one of the essential hydrometeorological parameters studied in the world at present. With the continuous development of the global navigation satellite system (GNSS), a technique called GNSS interferometric reflectometry (GNSS-IR) became widely used in ground SM inversion. Therefore, based on the frequency, amplitude and phase of signal-to-noise ratio residuals (δSNR), this study takes P037 and P043 stations set by UNAVCO in the United States as examples and develops the research of SM inversion from random forest regression (RFR) prediction. The experimental results show that the retrieval accuracy of SM under different practical schemes can be in descending order: L1 + L2 dual frequency combination > L2 single frequency > L1 single frequency. It is confirmed that the experimental scheme based on the L1 + L2 dual-frequency combination is beneficial to the inversion of SM. In the L1 + L2 dual-frequency combination, the prediction set accuracy of the P037 station is as follows: R is 0.796, root mean square error (RMSE) is 0.032 cm3 cm−3, ME is 0.002 cm3 cm−3. The prediction accuracy of the P043 station is as follows: R is 0.858, RMSE is 0.039 cm3 cm−3, ME is −0.009 cm3 cm−3. Among them, the RMSE of the L1 + L2 dual-frequency combination of the two stations has an improvement effect of 13%–37% compared with their single-frequency, which has a noticeable improvement effect. The difference between the SM retrieved by GNSS-IR and the reference value of PBO-H2O is concentrated around 0, further showing the accuracy of SM retrieved by GNSS-IR technology. To sum up, this study considers that SM retrieval based on the RFR model has good reliability and accuracy, which makes GNSS-IR technology an efficient means for SM retrieval. With the continuous improvement of the GNSS system and technology, the application of GNSS-IR technology in SM will become broader.
Parameter sharing fault data generation method based on diffusion model under imbalance data
Authors: Xiao Zhengming , Li Chengjunyi , Liu Tao , Liu Wenbin , Mo Shuai , Houjoh Haruo
Published: July 2024

Rotating machinery will inevitably fail under long-term heavy load working conditions. Obtaining enough data to train the deep learning model can enable managers to detect and deal with related failures in time, which greatly improves the safety of equipment operation. Mechanical fault samples are often much smaller than healthy samples. Traditional data enhancement methods mostly change the original data, but cannot improve the diversity of its features, so that the number of fault samples becomes larger, but the features remain unchanged. Aiming at the above problems, a diffusion model based on parameter sharing and inverted bottleneck residual structure (DDPM) is proposed. Firstly, the diffusion process gradually covers the original data with Gaussian noise, to learn the corresponding fault characteristics of the original data. In the diffusion process, the parameter sharing attention mechanism is embedded in the learning process of the diffusion process. Then, the feature extraction module is constructed by using the inverted bottleneck residual structure to enhance the learning ability of the network. After obtaining the fault characteristics of the original data, the reverse process of the results restores the Gaussian noise to data with different fault characteristics through the same steps as the diffusion process. By comparing the results of various generation models and analyzing the characteristics of the generated data, the feasibility and universality of the proposed method in data augmentation tasks are verified.
Frictional resistance and delamination mechanisms in 2D tungsten diselenide revealed by multi-scale scratch and in-situ observations
Authors: Paul Tanaji , Dolmetsch Tyler , Lou Lihua , Agarwal Arvind
Published: July 2024

Friction phenomena in two-dimensional (2D) materials are conventionally studied at atomic length scales in a few layers using low-load techniques. However, the advancement of 2D materials for semiconductor and electronic applications requires an understanding of friction and delamination at a few micrometers length scale and hundreds of layers. To bridge this gap, the present study investigates frictional resistance and delamination mechanisms in 2D tungsten diselenide (WSe2) at 10 µm length and 100–500 nm depths using an integrated atomic force microscopy (AFM), high-load nanoscratch, and in-situ scanning electron microscopic (SEM) observations. AFM revealed a heterogenous distribution of frictional resistance in a single WSe2 layer originating from surface ripples, with the mean increasing from 8.7 to 79.1 nN as the imposed force increased from 20 to 80 nN. High-load in-situ nano-scratch tests delineated the role of the individual layers in the mechanism of multi-layer delamination under an SEM. Delamination during scratch consists of stick-slip motion with friction force increasing in each successive slip, manifested as increasing slope of lateral force curves with scratch depth from 10.9 to 13.0 (× 103) Nm−1. Delamination is followed by cyclic fracture of WSe2 layers where the puckering effect results in adherence of layers to the nanoscratch probe, increasing the local maximum of lateral force from 89.3 to 205.6 µN. This establishment of the interconnectedness between friction in single-layer and delamination at hundreds of layers harbors the potential for utilizing these materials in semiconductor devices with reduced energy losses and enhanced performance.
Bias-dependent photoresponse of Td-WTe2 grown by chemical vapor deposition
Authors: Cao Yupeng , Cao Aiping , Li Shubing , Tang Jianli , Hu Rui , Shang Liyan , Li Yawei , Jiang Kai , Zhang Jinzhong , Zhu Liangqing , Hu Zhigao
Published: July 2024

The type-II Weyl semimetal Td-WTe2 is one of the wonder materials for high-performance optoelectronic devices. We report the self-powered Td-WTe2 photodetectors and their bias-dependent photoresponse in the visible region (405, 520, 638 nm) driven by the bulk photovoltaic effect. The device shows the responsivity of 15.8 mAW−1 and detectivity of 5.2 × 109 Jones at 520 nm. Besides, the response time of the WTe2 photodetector shows the strong bias-voltage dependent property. This work offers a physical reference for understanding the photoresponse process of Td-WTe2 photodetectors.
Photo-switching operation of MoS2 field effect transistor by photoisomerization of azobenzene in solution delivered on a microfluidic platform
Authors: Nasiruddin Md , Wang Zhipeng , Waizumi Hiroki , Afroz Fatema Tul , Takaoka Tsuyoshi , Sainoo Yasuyuki , Fukuyama Mao , Komeda Tadahiro
Published: July 2024

Combining the photoisomerization of molecules with an electrical device is important for developing optoelectronic devices. Field effect transistors (FETs) with atomically thin channels are suitable for this purpose because the FET properties respond to chemical changes in molecules. Since the photoisomerization wavelength of the switching molecules can be tuned, complex logic operations can be realized if a specific molecule is delivered to the target FET of an integrated circuit. However, conventional techniques for transferring molecules, such as drop casting and sublimation, cannot efficiently realize this goal. In this study, we fabricated a MoS2 FET device combined with a microfluidic platform, wherein the MoS2 channel was in contact with the flow of an azobenzene solution in isopropyl alcohol as the solvent. UV radiation (365 nm) and thermal relaxation realize the cycle of trans- and cis-azobenzene states and the switching of the substantial FET properties. This study demonstrated the feasibility of using the solution for optical switching of the MoS2-FET, which can realize quick phase changes in the molecule and the delivery of the molecule to the target FET by a microfluidic platform.