bluuebunny/crossref_metadata_2025 huggingface dataset:
Interface and Heteroatom Engineering in Graphene/g-C3N4 Heterostructures: A Pathway to High-Efficiency Metal-Free Catalysts for Hydrogen Evolution Reaction
Authors: wang siyao , Zhao Jingxiang
Published: February 2025

As a clean and sustainable energy source, hydrogen is expected to play a crucial role in addressing excessive carbon dioxide emissions and the depletion of fossil fuels. Herein, by means of density functional theory (DFT) computations, we have systematically investigated the effects of interface engineering in a series of graphene/ g-C3N4 (G/g-C3N4) with heteroatom doping (X-G/g-C3N4 and G/X-g-C3N4, X = B, N, Si, P and S) on hydrogen evolution reaction (HER) catalytic performance. Our results reveal that these X-doped G/g-C3N4 interfaces exhibit excellent stability, enhanced metallic features, terrific mechanic properties and exceptional magnetic properties. Remarkably, through precise regulation of the positioning of Si or P heteroatom, X-G/g-C3N4 interfaces demonstrate outstanding excellent catalytic performance, characterized by hydrogen adsorption free energy (∆GH*) values approaching zero, which can be ascribed to its appropriately positioned p-band centers near the Fermi level. This work provides valuable insights for the rational design of HER catalysts aimed at sustainable high-purity H2 production.
Inducing in-plane structural and magnetic anisotropy in a thick polycrystalline nickel ﬁlm coupled to LiNbO3 substrate
Authors: Mirfakhraie Seyed Alireza , Christienne Louis , Huang Tianwen , Becerra Loı̈c , Hrabovsky David , Talleb Hakeim , Gensbittel Aurélie , Rovillain Pauline , Zheng Yunlin , Marangolo Massimiliano
Published: February 2025

This study unveils mechanisms of thermally induced in-plane magnetic anisotropy in a 2 µm thick polycrystalline ﬁlm of nickel sputtered on lithium niobate Y-cut substrate at room temperature. We show that the appearance of in-plane magnetic anisotropy is correlated to in-plane anisotropic strain in nickel ﬁlms, resulting from the coupling between the ﬁlm and the substrate. Thermal annealing at moderate temperatures until 250ﬃC under vacuum has permitted to modify signiﬁcantly the strain state in the nickel ﬁlm. The native in-plane contractive strain in the as-grown ﬁlm has been gradually released and becomes anisotropic with annealing. It is demonstrated that the resulting strain is mainly due to the mismatch in thermal expansion between the ﬁlm and the substrate, but also to the anisotropic strain relaxation counting for 25% of the total in-plane anisotropic strain. In-plane magnetic anisotropy of the nickel ﬁlm is then highly enhanced and completely released once the ﬁlm is peeled oﬀ from the substrate. This study sheds light on coupling between magnetostrictive and piezoelectric materials, providing a better understanding of the magnetoelectric eﬀect in composite heterostructures.
Structural and electronic properties of bulk Li2O2: first-principles simulations based on numerical atomic orbitals
Authors: Masanja Paul M. , Fernández-Ruiz Toraya , Tarimo Esther J. , Carral-Sainz Nayara , PULAPA VENKATA KANAKA RAO , singh vijay , Mwankemwa Bernard , Garcia Lastra Juan Maria , García-Fernández Pablo , Junquera Javier
Published: February 2025

The development of advanced materials with high specific energy is crucial for enabling sustainable energy storage solutions, particularly in applications such as lithium-air batteries. Lithium peroxide (Li2O2) is a key discharge product in non-aqueous lithium-air systems, where its structural and electronic properties significantly influence battery performance. In this work, we investigate the atomic structure, electronic band structure, and Wannier functions of bulk Li2O2 using density functional theory. The performance of different basis sets of numerical atomic orbitals are compared with respect to a converged plane-wave basis results. We analyze the material’s ionic characteristics, the formation of molecular orbitals in oxygen dimers, and the band gap discrepancies between various computational approaches. Furthermore, we develop a localized Wannier basis to model electron-vibration interactions and explore their implications for polaron formation. Our findings provide a chemically intuitive framework for understanding electron-lattice coupling and offer a basis for constructing reduced models that accurately describe the dynamics of polarons in Li2O2. These insights contribute to the broader goal of improving energy storage technologies and advancing the field of materials design.
The anomalous temperature dependent low energy electron diffraction intensity at epitaxial Sr3Ir2O7 thin film surfaces
Authors: Adegbite Peace Ikeoluwa , Subedi Arjun , Zhang Yuanyuan , Hong Xia , Komesu Takashi , Dowben Peter A
Published: February 2025

We report on the temperature dependent low energy electron diffraction (LEED) studies of 12 nm epitaxial Sr3Ir2O7(001) thin films. The Debye temperature has been extracted from the temperature-dependence of LEED intensity at different electron kinetic energies. For the most surface sensitive LEED obtained with lowest electron kinetic energies, for temperatures above 410 K, the extracted surface Debye temperature is 270±22 K, which is much lower than the 488±40 K Debye temperature obtained using higher electron kinetic energies. Surprisingly, the LEED diffraction intensity with lowest electron kinetic energies increase, rather than decrease, with increasing sample temperatures up to about 440 K. This anomalous behavior has been attributed to the reduction of the quasi-harmonic lattice vibrational amplitudes along the surface normal. This damping of the normal mode vibrations, with increasing temperature, results from the enhanced electronic screening via thermally activated carriers. This scenario is corroborated by the transport measurement, showing Sr3Ir2O7 is a narrow band Mott insulator with a band gap of about 32 meV. We have identified criteria for finding anomalous scattering behavior in other transition metal oxide systems. The LEED data indicates that the surface symmetry of the epitaxial Sr3Ir2O7(001) thin films is C4v.
A 3D Optical Microscopic Imaging System Based on PSO-BPNN-PID Control and Image Pyramid Transform Fusion with Experimental Verification
Authors: Wu Jim-Wei , Chen Bo-Hao , Li Jia-Cheng , Yu Jen-te
Published: February 2025

The limited depth of field of optical microscopes typically results in the blurring of all but a small portion of the image, making it difficult to assess the height, shape, and surface profile of samples. This issue can be partly resolved by capturing a series of images at various sample distances by adjusting the piezoelectric stage; however, scanning performance is prone to perturbations resulting from nonlinear piezoelectric response characteristics. This paper presents a novel three-dimensional optical microscopic imaging system that uses a particle swarm optimization control scheme in parallel with a back-propagation neural network to achieve high-precision trajectory tracking. The system also features an algorithm to perform image pyramid transform fusion, image stitching, and 2D-to-3D conversion to enable the capture of 3D surface profiles of high accuracy. In experiments, the proposed scheme significantly outperformed existing methods in terms of accuracy and the level of detail.
A novel tacholess order tracking method for planetary gearbox fault detection under variable rotational speed conditions
Authors: Wang Chaoge , Wang Ran , Huang Yuanyuan , Wang Lijun , Li Hongkun
Published: February 2025

Planetary gearbox generally operates under variable speed conditions in response to actual industrial production requirements, which is prone to cause single or compound fault. The planetary gearbox fault signal exhibits time-varying, weak, and complex characteristics under varying conditions, and common diagnostic approaches are difficult to effectively extract and reveal fault-related features. In addition, the computed order tracking requires speed signal as auxiliary calculation. Unfortunately, due to economic and installation space limitations, encoders and tachometers are not always available, which poses a huge challenge for extracting variable speed planetary gearbox fault. To tackle these challenges, a novel tacholess order tracking method based on improved adaptive chirp mode decomposition (IACMD) and adaptive mximum second-order cyclostationarity blind deconvolution (CYCBD) is proposed for diagnosing planetary gearbox single and composite fault in this contribution. Firstly, the IACMD algorithm is utilized to adaptively decompose the fault signal, which constructs a composite index (CI)-based signal mode selection and recombination scheme to perform optimal modal decomposition. Secondly, the instantaneous dominant meshing multiply (IDMM) trend line with obvious amplitude advantage is extracted from the time-frequency representation of the original fault signal, and then converted to the reference shaft rotation frequency to perform angle domain resampling on sensitive model with the highest CI value. Thirdly, the adaptive CYCBD is adopted to deconvolute the angular domain sensitive modal to heighten the weak fault signatures. Finally, envelope spectrum of improved signal is utilized to identify prominent fault characteristic orders and ascertain failure type. Both numerical simulations and practical engineering data in different planetary gearbox failure cases have been thoroughly examined to demonstrate the correctness and feasibility of the proposed approach. Moreover, compared with some existing technologies demonstrates the superiority of the proposed approach.
Multi-Scale Geometric Transformer for Tire Fragment Stitching with Small Feature Differences
Authors: Jiao Wenhua , wang zhaoyi , Yifei You , Zhang Tong , Liu Xiaofei , Liu Zhenfei , Zuo Mingcheng
Published: February 2025

Tire is a vital component of any vehicle, and the surface characteristics have a considerable impact on overall performance. Given the limitations of the sensor's scanning angle, it is imperative that the fragments of the t ire be stitched together to reconstruct a complete tire model. Notably, the smoothness of the tire surface's geometric structure and the subtle differences in small-scale features have resulted in inaccurate stitching and mismatches. This paper proposes an approach based on a Multi-Scale Geometric Transformer (MSGT) for high accuracy and robustness. Firstly, the multiscale geometric structure embedding module extracts the details and overall information of the tire surface at different scales. A gating mechanism is introduced to fuse the distance and angle features to enhance the sensitivity and expressiveness of MSGT to small-scale features. Then, we employ a Global Attention Mechanism (GAM) that combines channel and spatial information to enhance feature differentiation, causing the model to select effective features in various regions of the tire. To further tackle mismatch and uneven distribution existing in the tire point cloud data, we propose an adaptive dynamic thresholding network that dynamically adjusts thresholds based on the distribution characteristics in tread and non-tread areas, effectively filtering out low-confidence matched point pairs. The experiments are conducted on the 3DMatch and self built tire datasets,-with the results demonstrating that MSGT significantly outperforms the other four mainstream deep learning methods in terms of stitching accuracy and robustness. Consequently, the superior performance of MSGT in tire stitching scenarios is validated.
Self-supervised U-transformer network with mask reconstruction for metal artifact reduction
Authors: Kong Fanning , Shi Zaifeng , Cao Huaisheng , Hao Yudong , Cao Qingjie
Published: February 2025

Objective. Metal artifacts severely damaged human tissue information from the computed tomography (CT) image, posing significant challenges to disease diagnosis. Deep learning (DL) has been widely explored for the metal artifact reduction (MAR) task. Nevertheless, paired metal artifact CT datasets suitable for training do not exist in reality. Although the synthetic CT image dataset provides additional training data, the trained networks still generalize poorly to real metal artifact data.Approach. A self-supervised U-shaped Transformer network (SUTransNet) is proposed to focus on model generalizability enhancement in MAR tasks. This framework consists of a self-supervised mask reconstruction pre-text task and a down-stream task. In the pre-text task, the CT images are randomly corrupted by masks. They are recovered with themselves as the label, aiming at acquiring the artifacts and tissue structure of the actual physical situation. Down-stream task fine-tunes MAR target through labeled images. Utilizing the multi-layer long-range feature extraction capabilities of the Transformer efficiently captures features of metal artifacts. The incorporation of the MAR bottleneck allows for the distinction of metal artifact features through cross-channel self-attention.Main result. Experiments demonstrate that the framework maintains strong generalization ability in the MAR task, effectively preserving tissue details while suppressing metal artifacts. The results achieved a peak signal-to-noise ratio (PSNR) of 43.86 dB and a structural similarity index (SSIM) of 0.9863 while ensuring the efficiency of the model inference. In addition, the Dice coefficient and Mean Intersection over Union (MIoU) are improved by 11.70% and 9.51% in the segmentation of the MAR image, respectively.Significance. The combination of unlabeled real-artifact CT images and labeled synthetic-artifact CT images facilitates a self-supervised learning process that positively contributes to model generalizability.
Intelligent risk stratification of hypertension based on ambulatory blood pressure monitoring and machine learning algorithms
Authors: Deng Muqing , Guo Junsheng , Li Boyan , Yang Jingfen , Zhang Xiaobo , Liang Dandan , Wang Yanjiao , Huang Xiaoyu
Published: February 2025

Risk stratification of hypertension plays a crucial role in the treatment decisionsand medication guidance during clinical practices. Although fruitful achievements have beenreported on risk stratification of hypertension, the potential use of ambulatory blood pressuremonitoring data is not well investigated. Different from single measuring blood pressuredata, long-term blood pressure monitoring data can provide more comprehensive dynamicalblood pressure information. Therefore, this paper proposes an intelligent hypertension riskstratification method based on ambulatory blood pressure monitoring data and improvedmachine learning algorithms. A total of 262 patients with hypertension are enrolled at People’sHospital of Yangjiang, in which 93 subjects are with simple hypertension and 169 subjectshave hypertension with complication. Time-domain features, frequency-domain features,nonlinear dynamics features and correlation features underlying time-varying ambulatoryblood pressure monitoring data are extracted to obtain discriminative feature representations.Synthetic minority over-sampling (SMOTE) algorithm is applied to solve the problem of databalancing. The particle swarm optimization (PSO) combined with kernel extreme learningmachine (KELM) is employed for feature fusion and optimization. The proposed method canyield a diagnostic accuracy of 93.7%, 97.8%, and 98.4% under two-, five- and ten-fold crossvalidation, which demonstrates hypertension risk stratification in an intuitive, quantizablemanner using multi-dimensional feature representation and learning. The proposed methodis expected to provide early warning for latent serious cardiovascular diseases before obvioussymptoms are present.
Control of axial direction electron temperature distribution by gradient DC magnetic field in inductively coupled plasma
Authors: Jiang Yilang , He You , Seo Beom-Jun , Lee Myoung-Jae , Kim Ju Ho , Chung Chin-Wook
Published: February 2025

A gradient magnetic field was applied in the axial direction of an inductively coupled plasma (ICP) by controlling the currents of the upper and lower coils of the Helmholtz coil, respectively. This control changed the magnetic field conditions of electron cyclotron resonance (ECR) along the axial position of the chamber. The experiment was conducted under a low-pressure (0.67 Pa) argon discharge with a driving frequency of 60 MHz and radio frequency (RF) power of 300 W. The axial distributions of the electron temperature and ion density in the chamber were measured using a floating harmonic probe (FHP). Due to the ECR effect, the electron temperature along the axial direction was controlled by the Helmholtz coil currents. Considering the direction of the planar antenna towards the chamber bias electrode as the positive direction, a higher ion density was observed at a positive gradient magnetic field. The distribution of ion flux on the surface of the bias electrode was measured using a two-dimensional (2D) FHP. Although the gradient magnetic field increased the ion flux, the 2D distribution profile remained unchanged. The variations in electron temperature and ion density under these magnetic field conditions were analyzed using plasma simulations based on the fluid approximation method. The study demonstrates how adjusting magnetic field conditions can enhance ion bombardment energy and etching rates in plasma processing.
Sensorless calibration of piezoelectric shunts using capacitance measurements
Authors: Richardt Jens Damholt , Lossouarn Boris , Høgsberg Jan , Deü Jean-François
Published: February 2025

In this work, a new experimental shunt tuning procedure is proposed for piezoelectric shunts targeting a single vibration mode of a flexible structure. The procedure is based on measurements of the dynamic capacitance of the piezoelectric transducer, eliminating the need for additional sensors or actuators. It is demonstrated that all required electromechanical parameters for shunt calibration can be determined from two extremum points on the dynamic capacitance curve. Corrections for the influence of residual modes are included to enable the consistent application of existing tuning expressions for various shunt topologies. The hardware of a digital shunt is used for the measurement of the dynamic capacitance allowing for low-cost implementation. The proposed method is validated numerically and experimentally through the calibration of a series RL shunt using both analog and digital components.
Process parametric and performance characteristics study of WED machined Ni-Ti-Hf high-temperature shape memory alloys: An experimental and artificial intelligence approach
Authors: V Balaji , Sahu Ranjeet Kumar , S Narendranath
Published: February 2025

In recent years, to meet the shortcomings of the conventional machining of Ni-Ti-Hf shape memory alloy (SMA), Wire Electric Discharge Machining (WEDM) as one of the unconventional machining methods, has emerged as the preferred method for processing SMAs. Therefore, in this study, according to the RSM-based Central Composite Design (CCD) layout, WED machining of Ni-Ti-Hf SMA is carried out using the control parameters like spark time (SON), spark pause time (SOFF), gap voltage (Vg), and dielectric flow rate (FDL). A General Regression Neural Network (GRNN) model was used to predict the critical WEDM responses: material removal rate (MRR), surface roughness (Ra), and kerf width (KW). The GRNN model closely agrees with the experimental WEDM responses, resulting in a Mean Absolute Percentage Error (MAPE) below 2%. Field Emission Scanning Electron Microscopy (FESEM) result revealed a recast layer thickness of 10.64 ± 2.06 µm and 38.19 ± 9.55 µm for the samples with the lowest surface roughness (Ra) and highest material removal rate (MRR), respectively. The shape recovery test result shows a less than 4% reduction in recovery ratio post-WEDM. Further, electrochemical corrosion studies revealed that owing to these surface defects, the corrosion rate increased with higher discharge energy. The corrosion rate of the base material, low Ra sample, and high MRR sample were 0.0013mm/year, 0.0128mm/year, and 0.0334mm/year, respectively.
A full-wave high-Tc superconducting transformer-rectifier flux pump activated with two electromagnets
Authors: Lin Yi , Hu Changhao , Yang Zaixing , Tan Yunfei , Geng Jianzhao
Published: February 2025

High-Tc superconducting (HTS) transformer-rectifier flux pumps (TRFPs) normally have higher efficiency and better controllability than their travelling-wave based counterparts. However, the majority of existing TRFPs require separate activation of the transformer and switch(es), which may increase the footprint and power demand of a system. In this paper, we propose a novel full-wave TRFP circuit topology that integrates induction and switching. The TRFP consists of an HTS loop and two electromagnets. Each electromagnet induces current in the HTS loop as well as switches a portion of the HTS loop in half ac duty cycle, thus achieving full-wave rectification. We developed a finite element simulation model to demonstrate its working principle in detail. In the meantime, a compact experimental prototype was fabricated and successfully supplied 300 A current to an HTS coil. The work effectively reduces the footprint and power demand of TRFPs. Moreover, the proposed TRFP can be considered as a simplified linear travelling-wave flux pump, and may help understand the fundamental interconnection between a travelling-wave flux pump and a TRFP.
Tunable diode effect in a superconducting tunnel junction with biharmonic drive
Authors: Scheer David , Seoane Souto Rubén , Hassler Fabian , Danon Jeroen
Published: February 2025

A Josephson diode is a superconducting circuit element that enables non-reciprocal transport, allowing a dissipationless supercurrent to preferentially flow in a single direction.Existing methods for achieving the required symmetry breaking mostly rely on specifically-designed materials or carefully-engineered circuits composed of multiple Josephson junctions.Here, we investigate the diode effect induced by applying a biharmonic drive to a conventional superconducting tunnel-junction. In the slow-driving regime, the effect is straightforward to understand in a simple adiabatic picture, providing insight in the tunability of the magnitude and directionality of the diode effect through the drive parameters. We then focus on the fast-driving regime, where we show how the more complex physics underlying the dynamics of the junction can be approximated as a cascaded two-tone mixing process. We derive analytic expressions for the diode efficiency as a function of drive parameters in the limit of small driving amplitudes.
Nonequilibrium Thermodynamics of a Superconducting Szilard Engine
Authors: Tang Kuen Wai , Ray Kyle J , Crutchfield James
Published: February 2025

We implement a Szilard engine using a 2-bit logical unit consisting of inductively coupled quantum flux parametrons (QFPs)—Josephson-junction superconducting circuits with applications in both the classical and quantum information processing regimes. Detailed simulations show that it is highly thermodynamically efficient while functioning as a Maxwell demon—converting heat to work. The physically-calibrated design is targeted to direct experimental exploration. However, in realizing experiments variations in Josephson junction fabrication introduce asymmetries that result in energy inefficiency and low operational fidelity. We provide a design solution that mitigates these practical challenges. The resulting platform is ideally suited to probe the thermodynamic foundations of information processing devices far from equilibrium.
Alpha particles registration by the single-side ultraviolet protected Makrofol® TP 244
Authors: Al-Sayed Abdallah , El Ghazaly Mahmoud , El-Naggar Hala I. , Abdel-Fattah Essam Mohammed , Abdeen Mostafa , Ghanim E.H.
Published: February 2025

The registration of 0.5 to 5.5 MeV alpha particles by the single-side UV-protected Makrofol® TP 244 was investigated. The alpha-particles irradiated Makrofol® TP 244 samples were chemically etched; the bulk etch rate amounts to 3.15 ± 0.24 μm/h. The visible light transmittance through Makrofol® TP 244 goes up from 58.0% at 400 nm to 83.8% at 700 nm. The etch-pits contrast was evaluated for the RGB color channels, the green channel has a maximum contrast of (45.0 ± 10.0) % compared with other color channels and RGB images. That the alpha particle etch-pits' contrast (C%) decreases with the increase in etching time as well as etch-pits' diameter. The etch pits revelation time of 0.5 to 5.5 MeV alpha particle was less than 0.5 hour at the applied etching conditions. The standard deviation of etch-pits' diameters from 0.5 to 3 MeV is less than 5%. For 4 to 5.5 MeV alpha particles, the standard deviation of etch pits goes up till etching time of 4 h, but near the end of the alpha particle's energy range, it decreases sharply. Accordingly, the Makrofol® TP 244 can detect 4 - 5.5 MeV alpha particles only when the removed-layer thickness is equal to or longer than the range of alpha particles. This minimizes the etch pit diameter uncertainty that gives rise to increase the energy resolution. The measurement of the etch pit diameters as a function of alpha particle energy shows the dynamic range limitations, between 0.5 to 3 MeV, the of Makrofol® TP 244 detector as alpha particles spectrometer.
Arbitrary quantum states preparation aided by deep reinforcement learning
Authors: Wang Zhao-Wei , Wang Zhao-Ming
Published: February 2025

The preparation of quantum states is essential in the realm of quantum information processing, and the development of efficient methodologies can significantly alleviate the strain on quantum resources. Under the framework of deep reinforcement learning (DRL), we integrate the initial and the target state information within the state preparation task together, so as to realize the control trajectory design between two arbitrary quantum states. Taking a semiconductor double quantum dots (DQDs) model as an example, our results demonstrate that the resulting control trajectories can effectively achieve arbitrary quantum state preparation (AQSP) for both single-qubit and two-qubit systems, with average fidelities of 0.9868 and 0.9556 for the test sets, respectively. For the DQDs, charge and nuclear noises will exist, thus decreases the average fidelity of AQSP. We have also incorporated noise amplitude as an input feature in the training process, leading to the development of noise-aware models. The control trajectories designed by these models can effectively suppress the influence of noise. Our research validates the effectiveness of DRL in quantum state preparation and offers solutions for multi-initial and multi-objective quantum control tasks, with potential for broader application in quantum control problems
Fluorescent Spectra of an Intensely-Driven Harmonic Oscillator
Authors: Hassan Shoukry S , Hassan Mohamed M , Frege Osman Mohamed
Published: February 2025

We investigate the transient and stationary physical spectra of scatteredradiation from a single quantized harmonic oscillator (HO) of frequency ωo, whichis resonantly driven by an intense driving field of real (amplitude) strength Ω ∼ ωoand damped in a Markovian broadband radiation reservoir. The influence of suchan intense field combined with manipulative spectral reservoir parameters results infield strength enhancement and a phase shift gain:  Ω→Ω√(1+γ'
2 (ωο)) eiγ' (ωο)), where γ'(ωο)=(dγ(ω)/dω)(ω=ωο) is the spectral rate of variation of the damping constantat resonance. This in turn leads to induced coherence in the average amplitude ofthe HO. Two cases of spectral distribution of the radiation reservoir are considered:the Ohmic power law and the Lorentz-Drude law. The spectral components of thescattered radiation in the transient and stationary regimes are identified analyticallyand computationally, and comparison is made with the non-intense driving field case (Ω≪ωο). The stationary spectrum is a symmetric Lorentzian of weight dependent onthe reservoir spectral parameters and of enhanced value compared with the non-intensefield case. The transient spectrum is composed of different lineshapes (Lorentzian,narrowed-Lorentzian, and dispersive) of oscillatory decaying weights. Interference ofthese transient-spectral components is initiated and caused by both types of non-zerocoherence, namely the initial coherence of the HO and the induced coherence in theintense field case, and induces asymmetric side oscillations of amplitude dependenton the reservoir spectral parameters. The present results for the fluorescent spectraof intensely-driven HO and its dependence on the environmental radiation reservoirspectral structure are adequately fitted for intensely driven collective Rydberg atomicsystems, as a ‘single site’ atomic sample, O(μm), and behaving as a single quantized HO.
Spreading of Liquid Films on a Vertical Rotational Cylinder with Different Contact Angles
Authors: Zhang Fan , Han Qixun , Sun Xianhu , Wang Gang , Yu Chengjiao , Ma Chicheng
Published: February 2025

This paper studied the flow dynamics of a thin liquid film falling down a vertical rotating cylinder. The influence of different contact angles, surface curvatures, and angular velocities on the flow and contact line characteristics of thin films was analyzed. To verify the results, numerical simulations based on a two-phase flow model were carried out and a comparison with results by lubrication theory was presented. The results indicated significant numerical differences between the two models: the two-phase flow model reduced the diffusion distance by 15.5 mm and the capillary ridge height by 34.43% compared to the lubrication model. This disparity primarily originates from the lubrication theory's neglect of the influence of the contact angle when applying boundary conditions in the precursor layer. It is worth noting that the flow profiles obtained by the two models agreed well with each other and the flow mechanism was well-explained. Numerical simulations indicate that wettability plays a crucial role in the diffusion process. A smaller contact angle (60°) significantly enhances capillary force, increasing the diffusion distance by 143.38 mm compared to a larger contact angle (120°). Furthermore, the smaller cylindrical radius (20 mm) increased capillary force, resulting in a 7.18% increase in the diffusion distance of the liquid film compared to the cylindrical radius (60 mm). Meanwhile, the rotation velocity significantly affects the liquid membrane flow. The capillary ridge height increased by 10.96% at a rotation speed of 120 rpm compared to the stationary state. The curvature and rotational velocity of the substrate significantly influence the axial fluctuations of the free surface. Besides, we investigated the influence of time-varying speeds and found that periodic variations induce regular oscillations in the liquid film. These oscillations lead to a peak-to-valley height variation of 0.132 mm, suggesting potential applications in the creation of nanostructures and coating patterns.
An Ultra-wideband Tightly Coupled Vivaldi Array with Current Loops for Transient Pulse Radiation
Authors: Xie Jialing , Chen Changhua , He Juntao , Qiao Hanqing , Fang Xu , Yi Chaolong , Qu Tuopu , An Jingxuan , Liu Anan , Yang Wenjin
Published: February 2025

A novel ultra-wideband tightly coupled Vivaldi array with current loop is proposed, which exhibits compactness and supports a wide operational bandwidth. The Vivaldi antenna, characterized by its inherent directivity, has been utilized in place of the conventional dipole antenna in tightly coupled arraying. This approach effectively mitigates the short-circuit resonances caused by the metallic reflective ground plane, thereby broadening the radiation bandwidth. To further enhance performance, a short-circuited branch is incorporated between the radiation arm of the Vivaldi antenna and the ground plane to guide the net current, aiming to suppress common-mode resonances and expand the impedance bandwidth. Concurrently, the radiation arm, short-circuited branch and ground plane form a current loop. When combined with the Vivaldi radiation structure, this configuration creates an electromagnetic combined antenna for complementary radiation, further reducing the low cutoff frequency. The element size of the array is 5 cm×5 cm×16.5 cm (0.083λL×0.083λL×0.275λL), with a low cutoff frequency of 0.5 GHz and a high cutoff frequency of over 10 GHz. A 4×4 UWB pulse array has been fabricated and its time-domain performance has been analyzed. The measured results are in good agreement with the simulated outcomes.
A Ship Image Encryption Algorithm Based on Novel Spatiotemporal Chaotic System
Authors: Si Ruiying , Hu Qing , Yan Xiaopeng
Published: February 2025

In order to prevent the remote-controlled lookout images of intelligent ships from being maliciously stolen or tampered with, and to ensure navigation and operation safety, this paper proposes an image encryption scheme based on ship-shore information transmission. The proposed scheme introduces the Sine Embedded Dynamic Random Coupled Map Lattice (SEDRCML), which replaces the static coupling coefficients e with a one-dimensional sine chaotic mapping. This modification enhances the system by exhibiting strong spatio-temporal dynamics and desirable chaotic properties. Additionally, it addresses the issue of unequal energy distribution among lattice points in the static coupling lattice. Based on the SEDRCML system, a novel bit-level encryption algorithm is developed to secure the remote lookout images of intelligent ships. This algorithm is primarily designed as a 3D dynamic multi-directional block zigzag-synchronous scrambling and diffusion algorithm, which simultaneously obfuscates pixel positions and modifies their values, thereby improving encryption efficiency. Simulation results of the proposed encryption and decryption algorithms indicate that the scheme provides a higher level of security for ship-shore image information transmission in remote control scenarios.
A theoretical and experimental study on optimal immersion method for microsphere-assisted microscopic imaging
Authors: Wang Yuqi , Yang Yujing , Zhang De-Long
Published: February 2025

With assistance of a microsphere immersed into a liquid medium, imaging resolution of microscope can exceed the Abbe diffraction limit, making the technique promising for super-resolution microscopic imaging. To achieve optimum assistance to the microscopic imaging, we have studied the microsphere immersion method in both theory and experiment. The impact of liquid immersion depth on the super-resolution imaging quality has been theoretically studied at first in both viewpoints of photonic nanojet and angular spectrum theory of backward propagation of waves. The results show that intensity, full width at half maximum and focal length of the focusing beam/spot are optimal at the semi-immersion state, resulting in considerable promotion of imaging contrast, resolution and magnification. To verify the theoretical results, experiments have been done in case that 10-μm-diameter SiO2 microspheres were semi-immersed into ethanol liquid. The results show that the semi-immersed SiO2 microspheres can assist, in the largest extent, the imaging with a contrast improved by 73.3% and a magnification increased by a fold of 1.9. In comparison with previous preliminary experimental study on super-resolution imaging of immersed microspheres, present paper performs a study in both theory and experiment, and proves that the semi-immersion state is optimum.
EEG-based recognition of hand movement and its parameter
Authors: Yan Yuxuan , Li Jianguang , Yin Mingyue
Published: February 2025

Brain-computer interface (BCI) is a cutting-edge technology that enables interaction with external devices by decoding human intentions, and is highly valuable in the fields of medical rehabilitation and human-robot collaboration. The technique of decoding motor intent for motor execution (ME) based on electroencephalographic (EEG) signals is in the feasibility study stage. There are still insufficient studies on the accuracy of motor execution EEG signal recognition in between-subjects classification to reach the level of realistic applications. This paper aims to investigate EEG signal-driven hand movement recognition by analyzing low-frequency time-domain (LFTD) information. Experiments with four types of hand movements, two force parameter (extraction and pushing) tasks, and a four-target directional displacement task were designed and executed, and the EEG data from thirteen healthy volunteers was collected. Sliding window approach is used to expand the dataset in order to address the issue of EEG signal overfitting. Furtherly, CNN-BiLSTM model, an end-to-end serial combination of a Bidirectional Long Short-Term Memory Network (BiLSTM) and Convolutional Neural Network (CNN) is constructed to classify the raw EEG data to recognize the hand movement. According to experimental data, the model is able to categorize four types of hand movements, extraction movements, pushing movements, and four target direction displacement movements with an accuracy of 99.14%±0.49%, 99.29%±0.11%, 99.23%±0.60%, and 98.11%± 0.23%, respectively. Furthermore, comparative tests conducted with alternative deep learning models (LSTM, CNN, EEGNet, CNN-LSTM) demonstrates that the CNN-BiLSTM model is with practicable accuracy in terms of EEG-based hand movement recognition and its parameter decoding.
Effects of zinc silicate additive on the physicochemical properties and cellular behaviors of 3D-printed magnesium phosphate bioceramic scaffolds
Authors: Fu Qiuyu , Xiong Jiaying , Zhang Chengcheng , Li Zikai , Gan Junxian , Huang Wenhao , Fu Wenhao , He Fupo , He Kunyan , Shi Haishan
Published: February 2025

Magnesium phosphate (MP) is a promising bone regeneration material, but it lacks the capacity to efficiently stimulate osteogenesis. In this work, zinc silicate (ZS) was used as an additive to modify MP bioceramics, and the MP-ZS composite bioceramic scaffolds with three-dimensional macroporous structure were fabricated by fiber deposition-based 3D printing and subsequent high-temperature sintering. New silicate phase was produced during sintering the MP-ZS bioceramic scaffolds. Incorporation of ZS allowed the MP-ZS scaffolds to have lower porosity and consequently higher compression strength. The MP-ZS scaffolds modified with 5 wt% ZS exhibited the highest compression strength. The MP-ZS scaffolds gradually degraded in the aqueous environment, accompanied by strength loss and pH variation. The MP-ZS scaffolds sustainably released Zn and Si ions, which could enhance cell proliferation and osteogenic differentiation. Overall, the MP-ZS bioceramic composite scaffolds could be considered as a new biomaterial for application in bone regeneration.
A Hermitian bypass to the non-Hermitian quantum theory
Authors: Bhasin Priyanshi , Das Tanmoy
Published: February 2025

Describing systems with non-Hermitian (NH) operators remains a challenge in quantum theory due to singularities (e.g., exceptional points and decoherence) arising from interactions with the environment. We introduce a well-defined computational basis for representing the NH Hamiltonian eigenstates, wherein singularities are shifted from the basis states to the expansion coefficients, simplifying the mathematical treatment of open quantum systems. Furthermore, we introduce a local `space-time' transformation on the computational basis that defines a generic dual space mapping. Interestingly, this transformation reveals a static/global symmetry for real/imaginary energy values, unveiling inherent conserved quantities in open quantum systems. Our formalism provides new insights into key features such as exceptional points, dual space maps, and the origin of symmetry-enforced real eigenvalues. The applicability of our framework extends to various branches of physics where NH operators manifest as ladder operators, order parameters, self-energies, projectors, and other entities.
Improving performance of crystalline silicon ultrathin solar cells using multi snowflake fractal nano-structures
Authors: Shameli Mohammad Ali , Yousefi Leila
Published: February 2025

In this paper, we propose a novel architecture for an ultrathin-film solar cell, integrating silicon multi-snowflake fractals into the electron-transport layer. In the proposed structure, each dielectric snowflake fractal is designed to trap sunlight within specific wavelength bands using multiple orders of Mie resonances and branch coupling, collectively covering the solar cell's operation bandwidth. This structure is numerically investigated using full-wave simulation with the FDFD method and by solving the drift and diffusion equations. The calculations demonstrate enhanced absorption across the whole wavelength range of 300 nm to 1100 nm, leading to an increased photo-generated current for both Transverse Electric (TE) and Transverse Magnetic (TM) polarizations of the incident light and at various angles of incidence. Simulation results illustrate a short-circuit current of 15.37 mA/cm² for the proposed structure, which is enhanced by a factor of 5.12 compared to a simple solar cell without fractal nanostructures inside.
Observation of robust polarization conversion via topological edge states in dimer chains
Authors: Zhang Han , Li Hui , Jiang Jie , Jiang Haitao , Sun Yong , Yang Yaping , Chen Hong , Guo Zhiwei
Published: February 2025

The polarization of electromagnetic waves is a fundamental property that influences their propagation direction and state, represents a critical physical parameter in modern applications such as signal transmission, target recognition, and precision measurement. Conventional polarization control devices based on metamaterials are often sensitive to structural perturbations, presenting challenges for practical applications. In contrast, topologically protected photonic devices have demonstrated that photon topological edge states can effectively overcome scattering losses caused by disorder and structural perturbations. The prospect of utilizing the robustness of topological edge states to design reliable electromagnetic wave polarization devices has thus become an increasingly significant research focus. We design and construct a curved photonic dimer chain composed of subwavelength resonators and experimentally verify that its topological edge states are immune to internal disorder perturbations, enabling efficient long-range electromagnetic wave polarization conversion. Based on this study, future investigations could explore more complex topological architectures, such as quasiperiodic or trimer chains, to achieve enhanced multifunctional polarization control. Furthermore, we could consider integrating exceptional points in non-Hermitian systems to design chiral polarization devices.
Instabilities in the Blistering of Two-Dimensional Materials
Authors: Pandey Mukesh , Wang Guorui , Singh Gagandeep , Ahuja Rajeev , Kumar Rakesh
Published: February 2025

The blistering of two-dimensional (2D) materials is susceptible to elastic solid- or substrate-based mechanical instabilities. The phase transition of confined matter inside a circular blister or the interfacial slippage at the perimeter of the blister may give rise to wrinkling and tenting instabilities in 2D material blisters. Extensive research has focused on gaining adhesion mechanical insights of such instabilities in 2D material blisters over smooth, rigid substrates like silicon. These insights carry profound implications for quantum emission, magneto-straintronics, plasmonics, and piezotronics. In contrast, blistering a 2D material over a viscoelastic substrate has not received much attention. This gap has led to the underexploration of unconventional but fascinating phenomenon of viscous fingering in 2D materials, recently realized experimentally. Therefore, there is a significant demand for comprehending the formation and dynamics of instabilities in 2D material blisters, necessitating a critical review to advance this field. This understanding is key to either promoting or mitigating such instabilities, which has huge importance for both fundamental research and emerging quantum technologies.
Analysis of the coupling coordination spatial network and driving factors of urban pollution and carbon emissions in China
Authors: Luo Qingfeng , Wang Jingyuan
Published: February 2025

With the acceleration of urbanization and industrialization, the issues of urban pollution emissions and carbon emissions have become increasingly prominent. The coupling coordination relationship between pollution emissions and carbon emissions has also become a key issue affecting sustainable urban development. This paper, based on a systems coupling perspective and social network analysis methods, examines the spatiotemporal characteristics and driving mechanisms of the coupling coordination between pollution emissions and carbon emissions in China. The findings that: (1) There are significant regional differences in the coupling coordination degree (CCD) of pollution and carbon emissions across various regions in China, exhibiting a gradient decreasing trend. The overall national improvement in coupling coordination is limited, indicating a need to strengthen synergistic governance of pollution reduction and carbon emission reduction. (2) The CCD between cities has undergone phased development from "barely coordinated—primary coordination—intermediate coordination", with most cities still at the primary coordination stage. The central and western regions have yet to reach a more advanced coordination state. (3) Analysis of the driving mechanisms indicates that various complex factors, such as economic development, industrial structure, environmental regulation, and green technological innovation, significantly influence coupling coordination.
Time-varying synergy/redundancy dominance in the human cerebral cortex
Authors: Pope Maria , Varley Thomas F , Puxeddu Maria Grazia , Faskowitz Joshua , Sporns Olaf
Published: February 2025

Recent work has emphasized the ubiquity of higher-order interactions in brain function. These interactions can be characterized as being either redundancy or synergy-dominated by applying tools from multivariate information theory. Though recent work has shown the importance of both synergistic and redundant interactions to brain function, their dynamic structure is still unknown. Here we analyze the moment-to-moment synergy and redundancy dominance of the fMRI BOLD signal during rest for 95 unrelated subjects to show that redundant and synergistic interactions have highly structured dynamics across many interaction sizes. The whole brain is strongly redundancy-dominated, with some subjects never experiencing a whole-brain synergistic moment. In small sets of brain regions, our analyses reveal that subsets which are redundancy dominated on average exhibit the most complex dynamic behavior as well as the most synergistic and most redundant time points. In accord with previous work, these regions frequently belong to a single coherent functional system, and our analysis reveals that they become synergistic when that functional system becomes momentarily disintegrated. Although larger subsets cannot be contained in a single functional network, similar patterns of instantaneous disintegration mark when they become synergistic. At all sizes of interaction, we find notable temporal structure of both synergy and redundancy-dominated interactions. We show that the interacting nodes change smoothly in time and have significant recurrence. Both of these properties make time-localized measures of synergy and redundancy highly relevant to future studies of behavior or cognition as time-resolved phenomena.