bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface flashover in 50 years: II. Material modification, structure optimisation, and characteristics enhancement
Authors: Li Zhen , Liu Ji , Ohki Yoshimichi , Chen George , Li Shengtao 
Published: November 2024

AbstractSurface flashover is a gas–solid interface insulation failure that significantly jeopardises the secure operation of advanced electronic, electrical, and spacecraft applications. Despite the widespread application of numerous material modification and structure optimisation technologies aimed at enhancing surface flashover performance, the influence mechanisms of the present technologies have yet to be systematically discussed and summarised. This review aims to introduce various material modification technologies while demonstrating their influence mechanisms on flashover performances by establishing relationships among ‘microscopic structure‐mesoscopic charge transport‐macroscopic insulation failure’. Moreover, it elucidates the effects of chemical structure on surface trap parameters and surface charge transport concerning flashover performance. The review categorises and presents structure optimisation technologies that govern electric field distribution. All identified technologies highlight that achieving a uniform tangential electric field and reducing the normal electric field can effectively enhance flashover performance. Finally, this review proposes recommendations encompassing mathematical, chemical, evaluation, and manufacturing technologies. This systematic summary of current technologies, their influence mechanisms, and associated advantages and disadvantages in improving surface insulation performance is anticipated to be a pivotal component in flashover and future dielectric theory.
Multi‐task image restoration network based on spatial aggregation attention and multi‐feature fusion
Authors: Peng Chunyan , Zhao Xueya , Chen Yangbo , Zhang Wanqing , Zheng Yuhui 
Published: November 2024

AbstractThe main purpose of image restoration is to recover high‐quality image content from degraded versions. However, current mainstream models tend to focus solely on spatial details or contextual semantics, resulting in poor repair effects. To address this issue, a multi‐task image repair network based on spatial aggregation attention and multi‐feature fusion (SAAM) is proposed. It utilizes the global semantic information from the low‐resolution subnetwork to guide the local feature extraction of the high‐resolution subnetwork, thereby preserving the overall image structure while enhancing local details. Additionally, to enhance the model's understanding and representation capabilities of images, the feature fusion mechanism (FFM) is designed to merge feature information from different levels. Finally, the spatial aggregation attention mechanism SAAM enhances the accuracy and quality of image restoration by weighting the importance of different regions in the image at multiple scales. The experimental results demonstrate that the proposed SAAM method outperforms similar approaches in image denoising, deraining and decracking tasks in peak signal‐to‐noise ratio, structural similarity and learned perceptual image patch similarity metrics. The model also exhibits promising performance in restoring real old photos and murals which demonstrates its generalizability.
Missing the mark? Identifying child sexual abuse material forum structure and key-players based on public replies and private messaging networks
Authors: Gnielka Frederic M. , Reichel Rebecca , Blokland Arjan , Daser Anton , de Boer Meike , Gannon Colm , Schmidt Alexander F. , Schäfer Thomas , Huikuri Salla , Staciwa Katarzyna , Lehmann Robert J. B. 
Published: November 2024

AbstractDarknet forums dedicated to child sexual abuse material (CSAM) attract thousands of users interacting with each other through online communications. Given finite resources, law enforcement agencies seek ways to effectively prioritise their investigative efforts by identifying key-players that are central to the forum community. For the identification of such users, law enforcement agencies typically rely on the communication network that can be derived from messages posted on the public part of the forum. Many forums, however, also allow for private communications between members, raising the question to what extent relying on only a single mode of communication biases key-player identification. Using data on both public and private communications on two large-scale darknet CSAM forums, two communication networks are derived and their structures analysed. Measures of centrality robustness are applied to ascertain the level of bias introduced when determining key-players on only one of the available networks. Findings show only a minority of members to participate in forum communication, and limited overlap between participants active in public and private communications. Key-players emerging from combining the public and private communications resemble those from the public network only, suggesting that police prioritisation based on public postings only is still ‘on mark’. Members who are central to the private communications network may nevertheless be of special law enforcement interest.
Enhanced Coupling of Superconductivity and Evolution of the Gap Structure in CsV3Sb5 via Ta Doping
Authors: Li 李 Yiwen 易文 , Zhu 朱 Zhengyan 政彦 , Li 李 Qing 庆 , Ye 叶 Yongze 永泽 , Wang 王 Zhiwei 秩伟 , Yao 姚 Yugui 裕贵 , Wen 闻 Hai-Hu 海虎 
Published: November 2024

Abstract
In this study, Kagome superconductors, i.e., CsV3Sb5 single crystals and its Ta-doped variant, Cs(V0.86Ta0.14)3Sb5, were studied in detail via specific heat measurements. Results revealed that the charge density wave (CDW) was suppressed and the superconducting transition temperature (T
c) considerably increased from 2.8 to 4.6 K upon Ta doping. The electronic specific heat of CsV3Sb5 was fitted with a model comprising an s-wave gap and a highly anisotropic extended s-wave gap, where 2Δ/k
B
T
c was smaller than the weak coupling limit of 3.5. Cs(V0.86Ta0.14)3Sb5 exhibited two isotropic s-wave gaps and yielded a larger gap of 2Δ/k
B
T
c = 5.04, indicating a significant enhancement in superconducting coupling. This evolution was attributed to the increased density of states near the Fermi level released by CDW gap suppression. These findings demonstrated that Ta doping enhanced superconducting coupling and variation of gap structure in CsV3Sb5.
Quantum Entanglement and Non-Hermiticity in Free-Fermion Systems
Authors: Chen Li-Mei , Zhou Yao , Chen Shuai A. , Ye Peng 
Published: November 2024

Abstract
This topical review article reports rapid progress on the generalization and application of entanglement in non-Hermitian free-fermion quantum systems. We begin by examining the realization of non-Hermitian quantum systems through the Lindblad master equation, alongside a review of typical non-Hermitian free-fermion systems that exhibit unique features. A pedagogical discussion is provided on the relationship between entanglement quantities and the correlation matrix in Hermitian systems. Building on this foundation, we focus on how entanglement concepts are extended to non-Hermitian systems from their Hermitian free-fermion counterparts, with a review of the general properties that emerge. Finally, we highlight various concrete studies, demonstrating that entanglement entropy remains a powerful diagnostic tool for characterizing non-Hermitian physics. The entanglement spectrum also reflects the topological characteristics of non-Hermitian topological systems, while unique non-Hermitian entanglement behaviors are also discussed. The review is concluded with several future directions. Through this review, we hope to provide a useful guide for researchers who are interested in entanglement in non-Hermitian quantum systems.
Suppression of clock-jitter noise and laser phase noise in arm locking
Authors: Wu Zhang-Qi , Wang Pan-Pan , Ke Jun , Shao Cheng-Gang 
Published: November 2024

Abstract
Arm-locking technique has been a focus of attention as one of the means to suppress the laser phase noise in space-based gravitational wave detector. The main idea of the arm-locking technique is to transfer the stability of the detector arm length to laser frequency by introducing a feedback control loop. Generally, laser phase noise will be suppressed by an amount similar to the magnitude of the controller gain. However, on the one hand, clock-jitter noise and optical bench motion noise, as the noise floor of the arm-locking technique, need to be suppressed. On the other hand, limited by the Doppler frequency pulling, the gain of the controller generally cannot be too large. It means that even if we do not consider clock-jitter noise and optical bench motion noise, it is difficult to suppress laser phase noise below the noise floor only by arm-locking technique. In this work, we combine self-referenced optical frequency combs and arm-locking technique to generate clock signals that are coherently referenced to the closed-loop laser beams, so that the clock-jitter noise is also suppressed by about the level of controller gain. We conduct a simulation on the above configuration, and the results show that the performance of the arm-locking is no longer limited by clock-jitter noise in the low-frequency band. To address the issue of insufficient laser phase noise suppression by the arm-locking technique, we further investigate time-delay interferometry (TDI) combinations under outputs of arbitrary arm-locking configurations. We obtain the equations for eliminating laser phase noise. To ensure that the TDI combinations can directly operate in the time domain, we derive a restricted solution space by assuming a specific form for the solutions.
Dynamic modelling and mechanical analysis of an inertial linear piezoelectric actuator with double stators
Authors: Xiong Yue , Yang Lin , Hong Xinwei , Wen Jiaquan , Zhang Jie 
Published: November 2024

Abstract
To achieve higher output performance in precision applications, and in order to gain deeper insight into operation principle, a dynamic model is established including the transmission relationship between the stators, the driving shaft, and the mover based on a slip–slip type inertial linear piezoelectric actuator with double stators. The influence of stator material and symmetry ratio of the excitation signal on the vibration characteristics of the stator and the output performance are investigated. This study reveals the relationship between these factors through a combination of simulations and experiments. Prototypes using several materials are machined and assembled, and the vibration characteristics and output performance are rigorously tested. The results obtained from the experimental measurements are consistent with the simulation results, confirming the validity and rationality of the dynamic model. The experimental results of the stator, as well as the actuator, are analyzed. It can be concluded that the actuator is able to output a larger effective displacement in one motion period with the increased symmetry ratio of the triangular wave signal, applied with a higher operating frequency, resulting in a higher output velocity of 42 mm s−1 and a larger load of 300 g with the steel stator, and a higher displacement resolution of 18 nm can be achieved using the AL alloy stator. This research not only provides an effective method for enhancing and selecting the desired output performance for the researched actuator but also can be extended to other slip-slip type inertial linear piezoelectric actuators.
Estimation, tuning, and evaluation of propagation direction behavior in superimposed orthogonal two-dimensional structure-borne traveling waves
Authors: Rogers William C , Albakri Mohammad I 
Published: November 2024

Abstract
Structure-borne traveling waves (SBTW) are observed in nature as a means for propulsion and locomotion of creatures on land and in the ocean. Recently, various approaches have been investigated to replicate this phenomenon. Previous studies have successfully generated SBTWs suitable for propulsion applications and particle motion on active surfaces. Much recent literature has focused on generating traveling waves that propagate only along a single axis for 1D and 2D structures. This limits their potential and does not take advantage of the full potential of 2D structures. This study examines the potential of employing superposition to control the propagation direction of 2D SBTW. This is investigated numerically using an experimentally validated Finite Element model of a 2D plate with piezoelectric actuators. The individual SBTWs are superimposed by simultaneously exciting two pairs of actuators that are aligned orthogonally on the surface of a plate. Traveling waves are excited in the plate using two-mode excitation. Structural intensity is utilized to develop quantifiable metrics to describe the overall propagation direction and uniformity, which are necessary for describing the complex propagation patterns encountered with 2D SBTW. The potential of the proposed approach along with developed tuning and evaluation methods are demonstrated through case studies of two plates, one square and one rectangular. For both cases, the overall direction of the SBTW is tuned to propagate for any direction between the individual SBTW. This was achieved while maintaining a high-quality overall SBTW. With this approach, 2D SBTW can be steered for wave-driven motion applications such as propulsion of the structure itself or conveying particles in any direction along the structure’s surface without compromising the quality of the overall traveling wave.
Evolution of critical current density in CaKFe4As4 with La-doping
Authors: Chen Yangsong , Wang Chunlei , Zu Yuhang , Kobayashi Yuto , Ichinose Ataru , Sakagami Ryosuke , Tamegai Tsuyoshi 
Published: November 2024

Abstract
Single crystals of (Ca1−x
La
x
)KFe4As4 (0

≤

x

≤

0.16) have been grown by using the self-flux method, and the evolution of physical properties including the critical current density (J
c

)

with La-doping has been investigated. T
c decreases monotonically with increasing x, while J
c at the same temperature and magnetic field increases initially and reach its maximum at x

=

0.082

. The increase in J
c is more obvious at low temperatures and high fields. At T = 5 K and H = 40 kOe, J
c reaches 0.34 MA cm−2, which is

∼
4

times larger than that for pure crystals. It is also found that anomalous temperature dependence of J
c in CaKFe4As4 is wiped away as the La content is increased. However, J
c shows non-monotonic field dependence (peak effect) at high fields in crystals with large x. In addition, we found that despite weak anisotropy of H
c2, there is extremely large anisotropy of J
c up to

∼
15

, which is most likely caused by novel planar defects in the crystal, similar to CaKFe4As4. J
c characteristics in (Ca1−x
La
x
)KFe4As4 with disorder outside FeAs planes is compared with that in CaK(Fe1−x
Co
x
)4As4 with disorder within FeAs planes.
The effect of single walled carbon nanotubes on conductivity and thermal properties of glass fiber reinforced composites
Authors: Bayirli Mehmet , Ilgaz Aykut 
Published: November 2024

Abstract
This paper reports on a comprehensive study of the effect of single-walled carbon nanotube (SWCNT) on the alternating current (AC) conductivity, thermal and morphological properties of the unsaturated polyester based glass fiber reinforced polymer composite (GFRPC). AC conductivity measurements were carried out using the impedance spectrum and thermal measurements were carried out using differential scanning calorimetry (DSC) at a temperature range of 24 °C–900 °C and heating rates of 20 °C min−1. Impedance results showed that the conductivity behavior in the nanotube-loaded composite laminate obeys a Jonscher-type mechanism. At low frequencies, the conductivity value remains almost constant for the doped material and takes the value of 10−5 S cm−1. It is observed that the AC conductivity starts to increase after the critical frequency value of approximately 103 Hz and increases up to 10−2 S cm−1 due to hopping and tunneling mechanisms caused by space charge polarization accumulated in the local regions at high frequencies. The pure material with an insulating nature also exhibited a typical insulating behavior. Thermal testing showed that nanotube reinforcement increases thermal conductivity in three different directions. DSC thermocurves analysis also revealed that the addition of carbon nanotubes increased the glass transition temperature of the material from 180 °C to 190 °C. The scaling and fractal analysis methods were also applied to obtain hetero morphological structure of materials. The fractal analysis results indicated that carbon nanotube doping to the standard sample increases the coating rates, scalability and heterogeneity of the solid phase surface of the sample. The coating rates of composite surfaces were calculated as 45% and 36%, respectively. Morphology analysis revealed that the probability of finding surface particles for the nanotube-doped sample decreased compared to the undoped sample, but the fractal dimension value increased. While this value was 1.83 in the pure sample, it increased to 1.92 in the nanotube material.
Stability analysis, modulation instability, and the analytical wave solitons to the fractional Boussinesq-Burgers system
Authors: Qawaqneh Haitham , Jari Hassan A , Altalbe Ali , Bekir Ahmet 
Published: November 2024

Abstract
The research is concerned with the novel analytical solitons to the (1+1)-D nonlinear Boussinesq-Burgers System (B-B S) in the sense of a new definition of fractional derivatives. The concerned system is helpful to describes the waves in different phenomenons, including proliferation of waves in shallow water, oceanic waves and many others. Authors gain the solutions involving trigonometric, hyperbolic, and rational functions by using the exp
a
function and the extended sinh-Gordon equation expansion (EShGEE) methods. Fractional derivative provides the better results than the present results. These results are helpful and useful in the different areas of applied sciences, including the optical fibers, telecommunications, plasma physics, fluid dynamics and many more. The solutions are shown by 2-dimensional, 3-dimensional, and contour graphs. The solutions are useful in further studies of the governing model. The stability process is performed to verify that the solutions are exact and accurate. The modulation instability is used to determine the steady-state stable results to the governing equation. The techniques utilized are both simple and effective.
Multipartite entanglement in crossing the quantum critical point
Authors: Sun Hao-Yu , Ge Zi-Yong , Fan Heng 
Published: November 2024

Abstract
We investigate the multipartite entanglement for a slow quantum quench crossing a critical point. We consider the quantum Ising model and the Lipkin-Meshkov-Glick model, which are local and full-connected quantum systems, respectively. The multipartite entanglement is quantified by quantum Fisher information with the generator defined as the operator of the ferromagnetic order parameter. The quench dynamics begins with a ground state in a paramagnetic phase, and then the transverse field is driven slowly to cross a quantum critical point, and ends with a zero transverse field. For the quantum Ising model, based on methods of matrix product states, we calculate the quantum Fisher information density of the final state. Numerical results of both linear and nonlinear quenches show that the quantum Fisher information density of the final state scales as a power law of the quench rate, which overall conforms to the prediction of the Kibble-Zurek mechanism with a small correction. We show that this correction results from the long-range behaviors. We also calculate the quantum Fisher information density in the Lipkin-Meshkov-Glick model. The results show that the scaling of quantum Fisher information in this full-connected system conforms to the Kibble-Zurek mechanism better, since the long-range physics cannot be defined in this nonlocal system. Our results reveal that the multipartite entanglement provides an alternative viewpoint to understand the dynamics of quantum phase transitions, specifically, the nontrivial long-range physics.
Quantum partial coherence measures constructed from Fisher information
Authors: Xuan Dong-Ping , Shen Zhong-Xi , Zhou Wen , Nan Hua , Fei Shao-Ming , Wang Zhi-Xi 
Published: November 2024

Abstract
Quantum mechanics gives a new breakthrough to the field of parameter estimation. In the realm of quantum metrology, the precision of parameter estimation is limited by the quantum Fisher information. We introduce the measures of partial coherence based on (quantum) Fisher information by taking into account the post-selective non-unitary parametrization process. These partial coherence measures present a clear operational interpretation by directly linking the coherence to the parameter estimation accuracy. Furthermore, we explore the distinctions between our partial coherence measure and the quantum Fisher information within the context of unitary parametrization. We provide an analytical expression for the partial coherence measure of two-qubit states. We elucidate the operational significance of the partial coherence measures by establishing the connections between the partial coherence measures and quantum state discrimination.
The effect of atomic concentration on the Cu-Sn IMC formation via molecular dynamic simulation
Authors: Zhang Jicheng , Li Xiaoye , Shi Mang 
Published: November 2024

Abstract
Full intermetallic compound (IMC) solder joints have great potential in high temperature devices because of the higher melting point and excellent mechanical performance. The key to accelerate the fabrication of full IMC solder joints is increasing the diffusion of atoms in solder materials and substrate, which can promote the combination of atoms to form IMC under extra driving forces. We raised a SLID bonding experiment by controlling the distance between Cu pads, aimed at adjusting the atomic concentration in liquid Sn. Results show that after 5 min of bonding at 560 K, when controlling the distance between the Cu pads in a SLID bonding experiment, an IMC thickness of 5.66 μm was achieved, which is 1.4 times higher than with traditional TC bonding technique. To explain this phenomenon, the effects of atomic concentration (measured by relative atomic concentration C) on the atomic diffusivity of atoms in solid Cu and liquid Sn was investigated via molecular dynamics simulations. It shows that the diffusion coefficient of Sn is up to 4.2 times higher when using the displacement control method (C = 0.8, D = 1.18E-06 cm2 s−1) compared to the traditional thermal-compression method (C = 0.91, D = 2.78E-07 cm2 s−1) because of the lower atomic concentration, which proved lower atomic concentration could effectively increase the diffusion coefficient of atoms in liquid Sn. This can be explained by the fact that the Sn atoms are both prevented from being balanced due to volume shrinkage and kept in an active state for diffusion. The conclusions discussed in this paper show us a potential way of increasing the fabrication of full IMC solder joints.