bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical study of breakdown voltage calculation and discharge characteristics of millimeter-level short air gap with a single water droplet
Authors: Liu Quan , Yang Lin , Hao Yanpeng , Li Licheng , Ding Jiabao , Hu Xingkun 
Published: December 2024

Abstract
Water droplets in the short air gap significantly affect the breakdown voltage. Currently, there is a lack of computational studies on the breakdown voltage and discharge process of short air gaps containing water droplets. In this paper, we establish a plasma dynamics-based model for the discharge in a millimeter-scale short air gap containing a single water droplet under ambient pressure and propose a breakdown voltage calculation method. We discuss typical discharge processes, calculate breakdown voltages for different gap lengths, validate the model through discharge phenomena and breakdown voltage, and analyze the impact of droplet parameters on discharge characteristics. The results show that negative streamer discharge in the cathode-side gap and positive streamer discharge in the anode-side gap occur sequentially, consistent with reported experimental results, with the positive streamer discharge being the primary process leading to gap breakdown. The average error rate between the calculated breakdown voltages for 4–8 mm gaps and reported experimental results is 4.85%, indicating good agreement. The observed streamer branching phenomenon may explain the difference between calculated and experimental breakdown voltages for the 10 mm gap. Under the influence of surface charges, low-conductivity droplets cause the discharge channel to propagate along the droplet surface. In contrast, high-conductivity droplets confine the discharge channel within the two gap sections. Increasing droplet diameter reduces breakdown voltage, with a critical value where the reduction becomes significant. Increased droplet deformation degree raises the breakdown voltage. This effect is related to the deviation of the positive streamer from the axial development and the reverse streamer generated on the droplet’s surface in different cases. The closer the droplet is to the electrode, the higher the breakdown voltage. The discharge is facilitated by the streamers generated on the droplet’s lower surface when it is close to the anode.
The role of volume recombination and resonance radiation transport in constriction of a: DC discharge in argon
Authors: Siasko A V , Pavlov S I , Karasev V Yu , Golubovskii Yu B 
Published: December 2024

Abstract
The work is aimed at revealing the influence of volume recombination on the formation of plasma parameters on the example of a diffuse and constricted positive column of a DC discharge in argon depending on the discharge current at pressures of 100–300 Torr·cm. At a qualitative level, the limiting transitions from the diffusion mode to the recombination mode of discharge maintenance are analyzed, which lead either to a rectangle-shaped radial profile of charged particles (arc discharge) or to a compressed profile (constricted discharge). Valuable information about the processes occurring in the plasma volume can be obtained from the ion current flowing toward the wall of the discharge tube since it is determined as a difference between the volume ionization and recombination. Based on a collision-radiative model, the ion current towards the tube wall was calculated and compared with the experimental results of probe measurements. In a diffuse discharge (low discharge current) a satisfactory agreement between the theory and experiment is observed. After the abrupt transition to the constricted regime (high discharge current), the theoretical values become strongly underestimated, and not able to describe the experimental data. The reasons for these discrepancies are analyzed. It is shown that the photoemission from the surface of the probe under the action of resonance photons gives an additional ion probe current which allows eliminating the discrepancies between the theory and experiment. Based on the Holstein–Biberman equation, the influence of the resonance radiation trapping on the discharge properties is revealed. The account of radiation trapping improves the agreement between the theory and experiment, including the values of the critical discharge currents at which the constriction occurs.
Acoustic waves in a halfspace material filled with random particulate
Authors: Piva Paulo S , Napal Kevish K , Gower Art L 
Published: December 2024

Abstract
Particulate materials include powders, emulsions, composites, and many others. This is why measuring these has become important for both industry and scientific applications. For industrial applications, the greatest need is to measure dense particulates, in-situ, and non-destructively. In theory, this could be achieved with acoustics: the standard method is to send an acoustic wave through the particulate and then attempt to measure the effective wave speed and attenuation. A major obstacle here is that it is not clear how to relate the effective wave speed and attenuation to the reflection and transmission coefficients, which are far easier to measure. This is because it has been very difficult to mathematically account for different background mediums. In this paper, we resolve this obstacle. To help comprehension, we present how to account for different background mediums for a simple case: a halfspace filled with a random particulate, where the background of the halfspace is different from the exterior medium. The key to solving this problem was to derive a systematic extension of a widely used closure approximation: the quasi-crystalline approximation. We present some numerical results to demonstrate that the reflection coefficient can be easily calculated for a broad range of frequencies and particle properties.
Synthesis and characterization of undoped and Co-Doped Bismuth Ferrite nanoparticles for photovoltaic applications
Authors: Zemene Samrawit , Yohannes Yonas Beyene , Wubetu Getasew Admasu 
Published: December 2024

Abstract
In this paper, we reported the structural, vibrational, and optical absorption properties of chemically synthesized multiferroic bismuth iron oxide (BiFeO3) (BFO) and cobalt-doped bismuth iron oxide (BFCO) nanoparticles. The nanoparticles were synthesized via sol–gel methods and annealed at 450 °C for a duration of two hours. Characterization was conducted through techniques such as UV–Vis spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), and Scanning Electron Microscope (SEM). XRD analysis revealed average crystallite sizes of 19.1 nm and 20.8 nm for BFO and BFCO, respectively, with no secondary phase observed in the cobalt-doped BFO nanoparticles. Structural analysis via XRD indicated a transformation from rhombohedral to orthorhombic symmetry in the doped BFO nanoparticles. The optical band gap energies were determined to be 2.43 eV for BFO and 2.33 eV for BFCO. The reduction in the band gap in BFCO may be help for relevant for the photovoltaic application. FTIR spectroscopy identified characteristic peaks, including the O–H single bond at 3417 cm−1 and vibrations corresponding to metal–oxygen/Fe–O, Bi–O stretching, and O–Fe–O bending vibrations in BFO and BFCO within the spectral range of 400–1000 cm−1. The morphology and crystallinity of these materials were assed using a SEM, revealing a progressively complex arrangement of flower structures in both BFO and BFCO.
Diffraction managed modulation instability of two-dimensional plane wave in competing cubic-quintic nonlinear media
Authors: Jiang Yumin , Ge Lijuan , Shen Ming 
Published: December 2024

Abstract
Modulation instability of two-dimensional plane wave is investigated in competing cubic-quintic nonlinear media with fourth order diffraction (FOD). Growth rate of modulation instability are obtained analytically with linear-stability analysis. Besides main band, another side band of instability spectra appears in some regions of anomalous FOD. Normal FOD promote, while anomalous FOD and competing self-defocusing quintic nonlinearity always suppress modulation instability. Analytical results are also verified numerically by employing split-step Fourier transform method.
Analyzing Stability and Dynamics of an Epidemic Model with Allee’s Effect and Mass Action Incidence Rates Incorporating Treatment Stategies.
Authors: Qurban Muhammad , Khaliq Abdul , saqib Muhammad 
Published: December 2024

Abstract
This paper focuses on transforming a continuous SIR epidemic model into its discrete&#xD;counterpart using a non-standard finite difference scheme, motivated by the rich dynamic behaviors often exhibited by discrete models. The study investigates the impact of Allee’s Effect&#xD;on disease progression by analyzing the existence of equilibrium points and determining their&#xD;stability and bifurcation conditions. Augmenting the model with these factors significantly&#xD;enhances our capacity to predict the course of the epidemic. Similarly, assessing the impact&#xD;of treatment on epidemic diseases is pivotal for disease control. A thorough understanding of&#xD;factors influencing disease dynamics, including Allee’s Effect, is crucial for effective modeling&#xD;and prediction of epidemic progression. The transmission rate of the disease fluctuates based&#xD;on individual isolation or treatment rates, and incorporating Allee’s Effect adds an extra layer&#xD;of complexity to this dynamic. Analyzing mathematical models based on these and similar&#xD;factors, including Allee’s Effect, allows us to glean insights into the disease’s trajectory. This&#xD;research investigates epidemic disease models that integrate mass action involving treatment,&#xD;while also considering the influence of Allee’s Effect. In our investigation, we explore the&#xD;existence of equilibrium points and establish the stability and bifurcation conditions of these&#xD;points in the context of Allee’s Effect. We complement our analysis with numerical examples.&#xD;To compare the behavior of the epidemic disease models under consideration, including those&#xD;accounting for Allee’s Effect, we present graphs illustrating the dynamic behaviors of our&#xD;populations.&#xD;
Dynamics of the novel multi-cavity hyperchaotic map and its DSP implementation
Authors: Zhang Zeping , Sun Kehui , Zhu Wanting , Wang Huihai 
Published: December 2024

Abstract
Based on the mathematical model of the Bernoulli lemniscate, we design a novel hyperchaotic map with a dual-cavity attractor. Through dynamical analyses, the results indicate that the proposed map is hyperchaos and has wide parameter range, large Lyapunov Exponents (LEs), and high Permutation Entropy (PE) complexity. In addition, two types of multi-cavity hyperchaotic maps are constructed by employing the fractal transformation and rotation transformation, respectively. The multi-cavity hyperchaotic maps have complex topological structures. The hyperchaotic maps are implemented on the digital signal processor (DSP) platform for practical application.
Exploring the discrepancy between Planck PR3 and ACT DR4
Authors: Hazra Dhiraj Kumar , Beringue Benjamin , Errard Josquin , Shafieloo Arman , Smoot George F. 
Published: December 2024

Abstract
We explore the scales and the extent of disagreement between Planck PR3 and Atacama
Cosmology Telescope (ACT) DR4 data. Planck and ACT data have substantial overlap in the
temperature anisotropy data between scales corresponding to multipoles ℓ ≃ 600–2500
with complementing coverage of larger angular scales by Planck and smaller angular scales by
ACT. Since the same cosmology should govern the anisotropy spectrum at all scales, we probe this
disagreement in the primordial power spectrum. We use a parametric form of power law primordial
spectrum that allows changes in the spectral tilt. We also reconstruct the primordial spectrum
with a non-parametric method from both Planck and ACT temperature data. We find the
disagreement exists within scales 0.08–0.16 Mpc-1 where ACT temperature data prefers
a scale invariant/blue spectrum. At scales larger and smaller than this window, ACT data strongly
prefers a red tilt, which is consistent with Planck. This change in the spectral tilt can be
identified in the ACT data at 2σ C.L. without using Planck data, indicating that the
tension is driven by different preferences for tilts within the ACT data. The addition of Planck data up to intermediate scales (ℓ ≤ 650) increases this significance to
3σ. Given the large overlap between Planck and ACT within 0.08–0.16 Mpc-1 and considering the internal consistency between different Planck temperature
and polarization spectra, the scope of new physics as a solution to the tension remains
limited. Our results — a strong preference for an intermediate transition in spectral tilt and
the variation of this preference in different data combinations — indicate that systematic
effects can be misperceived as new physics emerging from different non-standard cosmological
processes.
Gravitational waves from primordial black hole isocurvature: the effect of non-Gaussianities
Authors: He Xin-Chen , Cai Yi-Fu , Ma Xiao-Han , Papanikolaou Theodoros , Saridakis Emmanuel N. , Sasaki Misao 
Published: December 2024

Abstract
Ultra-light primordial black holes (PBHs) with masses M
PBH < 5 × 108g
can dominate transiently the energy budget of the Universe and reheat the Universe through their
evaporation taking place before Big Bang Nucleosynthesis. The isocurvature energy density
fluctuations associated to the inhomogeneous distribution of a population of such PBHs can induce
an abundant production of GWs due to second-order gravitational effects. In this work, we discuss
the effect of primordial non-Gaussianity on the clustering properties of PBHs and study the effect
of a clustered PBH population on the spectral shape of the aforementioned induced GW signal. In
particular, focusing on local-type non-Gaussianity we find a double-peaked GW signal with the
amplitude of the low-frequency peak being proportional to the square of the non-Gaussian parameter
τ
NL. Remarkably, depending on the PBH mass M
PBH and the initial abundance
of PBHs at formation time, i.e. ΩPNH,f, this double-peaked GW signal can lie well
within the frequency bands of forthcoming GW detectors, namely LISA, ET, SKA and BBO, hence
rendering this signal falsifiable by GW experiments and promoting it as a novel portal probing the
primordial non-Gaussianity.
Gauge theory meets cosmology
Authors: Bianchi Massimo , Dibitetto Giuseppe , Morales Jose Francisco 
Published: December 2024

Abstract
We reconsider linear perturbations around general Friedmann-Lemaitre-Robertson-Walker
(FLRW) cosmological backgrounds. Exploiting gauge freedom involving only time reparametrizations,
we write down classical background solutions analytically, for an arbitrary number of fluid
components. We then show that the time evolution of scalar and tensor adiabatic perturbations are
governed by Schrödinger-like differential equations of generalized Heun type. After recovering
known analytic results for a single-component fluid, we discuss more general situations with two
and three different fluid components, with special attention to the combination of radiation,
matter and vacuum energy, which is supposed to describe the ΛCDM model. The evolution of
linear perturbations of a flat ΛCDM universe is described by a two-transient model, where
the transitions from radiation to matter and matter to vacuum energy are governed by a Heun
equation and a Hypergeometric equation, respectively. We discuss an analytic approach to the
study of the general case, involving generalized Heun equations, that makes use of (quantum)
Seiberg-Witten curves for 𝒩 = 2 supersymmetric gauge theories and has proven to be very
effective in the analysis of Black-Hole, fuzzball and ECO perturbations.
Real-time Collision Detection of Dual Rotating Arm Positioner for Multi-object Fiber-fed Spectrographs
Authors: Zhou 周 Ming 明 , Zhang 张 Yong 勇 , Li 栗 Jian 剑 , Lv 吕 Guanru 冠儒 , Zhou 周 Zengxiang 增祥 , Liu 刘 Zhigang 志刚 , Wang 王 Jianping 建平 , Wang 王 Yingfu 应富 , Zhou 周 Jiahao 家豪 , Bai 白 Zhongrui 仲瑞 , Li 李 Ganyu 甘雨 , Wang 汪 Mengxin 梦欣 , Wang 王 Shuqing 淑青 , Hu 胡 Hongzhuan 红专 , Zhai 翟 Chao 超 , Chu 褚 Jiaru 家如 , Dong 董 Yiqiao 义乔 , Yuan 袁 Hailong 海龙 , Zhao 赵 Yongheng 永恒 , Chu 褚 Yaoquan 耀泉 , Zhang 张 Haotong 昊彤 
Published: December 2024

Abstract
Multi-object fiber spectroscopic survey is pivotal to astronomical research. Most spectroscopic telescopes are equipped with thousands of robotic fiber positioners designed to observe multiple celestial objects simultaneously. Despite this advancement, the risk of potential collisions between adjacent positioners, due to overlapping work zones, poses a significant challenge that could limit the telescope’s observing efficiency. In this study, we present a method based on deep learning to detect the collision of dual rotating arm positioner using the front-illuminated image from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). We employ a deep learning detection model based on the YOLOv5 object detection algorithm to identify and locate the collision zones. Furthermore, the BiSeNet image segmentation algorithm is applied to determine the positioners within these collision zones, ultimately identifying the collided positioners. Experimental results reveal a precision and recall of 90.20% and 85.44% respectively for our method. To verify our results further, we conducted a correlation analysis on the spectral flux in LAMOST survey data via direct measurement. The collision types of the LAMOST positioners are also analyzed, which provides guidance for optimizing the anti-collision algorithm in the future.
Prospects of using novel nonlinear crystals in SU(1,1) interferometry
Authors: Sabanin Artem , Paterova Anna 
Published: December 2024

Abstract
Nonlinear interferometry presents a powerful approach for infrared metrology by enabling measurements with visible or near-infrared detectors. In this study, we evaluate the potential of novel nonlinear crystals for mid-infrared ‘fingerprint’ spectroscopy based on nonlinear interferometry, focusing on the transparency range, nonlinear coefficients, and phase-matching capabilities of nonlinear crystals. We compare established materials like silver thiogallate (AgGaS2) with promising alternatives, including mercury thiogallate (HgGa2S4), barium gallium germanium sulphide (BaGa2GeS6), and barium gallium germanium selenide (BaGa2GeSe6). The selected nonlinear crystals exhibit higher nonlinear conversion efficiency compared to AgGaS2, with BaGa2GeS6 additionally offering a narrower angular spectrum of spontaneous parametric down conversion, advantageous in interferometric schemes. Our findings establish a pathway for integrating advanced crystal technologies into mid-infrared metrology and imaging systems, setting the stage for future developments in nonlinear interferometry and spectroscopy.
Understanding thermal hysteresis of ferroelectric phase transitions in BaTiO3 with combined first-principle-based approach and phase-field model
Authors: Shao 邵 Cancan 灿灿 , Huang 黄 Houbing 厚兵 
Published: December 2024

Abstract
Based on the principles of thermodynamics, we elucidate the fundamental reasons behind the hysteresis of spontaneous polarization in ferroelectric materials during heating and cooling processes. By utilizing the effective Hamiltonian method in conjuction with the phase-field model, we have successfully reproduced the thermal hysteresis observed in ferroelectric materials during phase transitions. The computational results regarding the electrocaloric effect from these two different computational scales closely align with experimental measurements. Furthermore, we analyze how the first-order ferroelectric phase transition gradually diminishes with an increasing applied electric field, exhibiting characteristics of second-order-like phase transition. By employing the characteristic parameters of thermal hysteresis, we have established a pathway for calculations across different computational scales, thereby providing theoretical support for further investigations into the properties of ferroelectric materials through concurrent multiscale simulations.
Temporal variation characteristics of cathode temperature in a magnetoplasmadynamic thruster
Authors: Zhou 周 Cheng 成 , Wu 吴 Peng 鹏 , Song 宋 Yun-Tao 云涛 , Zheng 郑 Jin-Xing 金星 , Li 李 Yong 永 , Wang 王 Ge 戈 , Liu 刘 Hai-Yang 海洋 
Published: December 2024

Abstract
The magnetoplasmadynamic thruster (MPDT) is characterized by its high specific impulse and substantial thrust density, making it a promising propulsion system for deep space exploration missions. In both laboratory experiments and practical applications, cathode ablation has emerged as a critical concern. An optical diagnostic approach based on monochromatic radiation temperature measurement, utilizing plume emission spectra and the selection of an appropriate test band, has been successfully employed. This method provides an accurate temperature distribution across the cathode surface, offering a novel testing technique for the optimization and evaluation of magnetic plasma thruster designs.
Nondestructive detection of atom counts in laser-trapped 171Yb atoms
Authors: Tian 田 Congcong 聪聪 , Zhu 朱 Qiang 强 , Wang 王 Bing 兵 , Xiong 熊 Dezhi 德智 , Xiong 熊 Zhuanxian 转贤 , He 贺 Lingxiang 凌翔 , Lyu 吕 Baolong 宝龙 
Published: December 2024

Abstract
We present the experimental demonstration of nondestructive detection of 171Yb atoms in a magneto-optical trap (MOT) based on phase shift measurement induced by the atoms on a weak off-resonant laser beam. After loading a green MOT of 171Yb atoms, the phase shift is obtained with a two-color Mach–Zehnder interferometer by means of ±45 MHz detuning with respect to the 1S0–1P1 transition. We measured a phase shift of about 100 mrad corresponding to an atom count of around 5 × 105. This demonstrates that it is possible to obtain the number of atoms without direct destructive measurement compared with the absorption imaging method. This scheme could be an important approach towards a high-precision lattice clock for clock operation through suppression of the impact of the Dick effect.
TMS-evoked potential propagation reflects effective brain connectivity
Authors: Daly Ian , Williams Nitin , Nasuto Slawomir J 
Published: December 2024

Abstract

Objective. Cognition is achieved through communication between brain regions. Consequently, there is considerable interest in measuring effective connectivity. A promising effective connectivity metric is transcranial magnetic stimulation (TMS) evoked potentials (TEPs), an inflection in amplitude of the electroencephalogram recorded from one brain region as a result of TMS applied to another region. However, the TEP is confounded by multiple factors and there is a need for further investigation of the TEP as a measure of effective connectivity and to compare it to existing statistical measures of effective connectivity. Approach. To this end, we used a pre-existing experimental dataset to compare TEPs between a motor control task with and without visual feedback. We then used the results to compare our TEP-based measures of effective connectivity to established statistical measures of effective connectivity provided by multivariate auto-regressive modelling. Main results. Our results reveal significantly more negative TEPs when feedback is not presented from 40 ms to 100 ms post-TMS over frontal and central channels. We also see significantly more positive later TEPs from 280–400 ms on the contra-lateral hemisphere motor and parietal channels when no feedback is presented. These results suggest differences in effective connectivity are induced by visual feedback of movement. We further find that the variation in one of these early TEPs (the N40) is reliably related to directed coherence. Significance. Taken together, these results indicate components of the TEPs serve as a measure of effective connectivity. Furthermore, our results also support the idea that effective connectivity is a dynamic process and, importantly, support the further use of TEPs in delineating region-to-region maps of changes in effective connectivity as a result of motor control feedback.