bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of pressurization on bubble dynamics of photoelectrochemical water splitting
Authors: Luo Xinyi , Xu Qiang , Nie Tengfei , She Yonglu , Guo Liejin
Published: December 2024

Energy consumption of hydrogen production significantly restricts the practical application of photoelectrochemical (PEC) water splitting technology for hydrogen production, despite its vital role in addressing the energy crisis. The direct high-pressure hydrogen production technology holds promise for reducing production costs and streamlining the overall process. This paper delved into the study of bubble dynamic characteristics of PEC water splitting reaction under elevated pressure operations by coupling a photoelectrochemical system with a high-speed microscopic camera. The results prove that the bubble growth behaviors are pressure-dependent. Pressurization leads to the simultaneous evolution of multiple bubbles along with bubble slip and coalescence on the photoelectrode surface. And the bubble detachment diameter and growth period are significantly reduced, suggesting that increasing pressure is conducive to promoting bubble detachment. Analysis of the results of linear sweep voltammetry and Tafel slope shows that elevated pressure leads to more challenging bubble nucleation. Furthermore, the time coefficient and growth coefficient of the bubble growth stage are computed, revealing that the diffusion-controlled stage dominates the bubble growth process post-pressurization. A force balance model is constructed in the initial process of bubble rising, and it is found that the terminal rise velocity of bubbles decreases when pressure increases. The effect of pressure on gas density was considered to calculate the gas production rate by bubble volume and growth period, discovering that the proportion of gas products in the form of dissolved oxygen in the liquid increases significantly under high pressure.
Simulation study of energetic-ion mass dependence on nonlinear development of lower hybrid wave instabilities
Authors: Toida Mieko , Kotani Tsubasa
Published: December 2024

In both space and fusion plasmas, energetic ions with a ring-like velocity distribution are present in various ion species with different masses. We study how the nonlinear development of lower hybrid wave (LHW) instabilities, driven by the ring-like energetic ions, depends on the mass of the energetic ions, by using the electromagnetic particle-in-cell simulation with a model where the energetic ions are continuously injected into a plasma. As expected from linear theory, the initial growth of the LHWs slows down as the energetic-ion mass (M) increases. However, long-time simulations have revealed that as M increases, the LHWs eventually grow to larger amplitudes. This is because the velocity distribution of the energetic ions, influenced by spreading due to wave development and reformation due to injection, can maintain a steep gradient when M is large. As a result, in a large M plasma, a greater part of the injected energy is converted to the energies of the electric field and background ions. In addition, it has been found that a larger value of M leads to an increase in the amplitudes of the second and third harmonics of the LHWs because of enhanced nonlinear wave-wave coupling.
Neural network-based numerical analysis of some convection-diffusion-based initial boundary-value problems
Authors: Khan Muhammad Sabeel , Abualnaja Khadijah M. , Sagheer Ayesha , Memon M. Asif , Fenta Amsalu
Published: December 2024

In this paper, we present a computational analysis of data-driven solutions of the convection–diffusion–reaction equation using Physics Informed Neural Networks (PINNs). PINNs enforce laws of physics when solving non-linear partial differential equations that govern physical dynamics. The PINN technique for solving boundary value problems in partial differential equations is presented as an alternative to the available numerical techniques. Three model initial-boundary value problems are implemented through MATLAB using the presented technique. The computed numerical solutions of these model problems are compared with the actual solution to observe the accuracy of the numerical implementation. It is noted that the predicted solution in the case of these model problems through PINNs is in strong agreement with the corresponding exact solution. The analysis of the presented algorithm is performed to observe what changes in the accuracy of the solution when the number of neurons and the number of layers working within the neural network structure are altered. Moreover, the impact of the number of training data points and collocation points on the model’s accuracy is also presented to develop a better understanding of the algorithm. It is observed that the presented method is capable of efficiently computing numerical solutions of boundary value problems in partial differential equations and has the potential to solve a large number of related problems that arise in engineering physics.
Global network control from local information
Authors: Haber Aleksandar , Molnar Ferenc , Motter Adilson E.
Published: December 2024

In the classical control of network systems, the control actions on a node are determined as a function of the states of all nodes in the network. Motivated by applications where the global state cannot be reconstructed in real time due to limitations in the collection, communication, and processing of data, here we introduce a control approach in which the control actions can be computed as a function of the states of the nodes within a limited state information neighborhood. The trade-off between the control performance and the size of this neighborhood is primarily determined by the condition number of the controllability Gramian. Our theoretical results are supported by simulations on regular and random networks and are further illustrated by an application to the control of power-grid synchronization. We demonstrate that for well-conditioned Gramians, there is no significant loss of control performance as the size of the state information neighborhood is reduced, allowing efficient control of large networks using only local information.
Stratified biphasic dip coating flows on permeable substrates
Authors: Kumanan Arasakumaran , Sathyanath Rahul , Usha R. , Kalpathy Sreeram K.
Published: December 2024

The present work models dip coating flows on saturated porous substrates in a biphasic configuration wherein two immiscible Newtonian liquids are simultaneously entrained. The model accounts for the effect of substrate permeability through a modified Navier slip boundary condition. New scaling laws have been derived for the two interface heights in the no-slip and strong-slip limits. Numerical solutions to the mathematical model predict that the presence of outer liquid reduces the effect of slip experienced by the inner liquid in the biphasic configuration when compared with slip effects in the monophasic configuration. This reduction of wall-slip effect is found to be amplified by increasing the interfacial tension between the two fluids. Moreover, the inner film thickness becomes independent of substrate surface permeability at high values of capillary number. Interestingly, the substrate permeability induces thickening effect on the outer liquid film at high values of permeability factor and a more viscous outer liquid. Process regime maps for inner and outer liquid film thickness as a function of permeability factor, withdrawal speed, and viscosity ratio have also been constructed.
Chaotic property in general fractional calculus
Authors: Kochubei Anatoly N.
Published: December 2024

We prove the chaos property, in the sense of Devaney, of the discrete-time fractional derivative understood in the framework of general fractional calculus. The latter means the discretization of a differential-convolution operator whose kernel has the Laplace transform belonging to the Stieltjes class.
An adaptive level-set/square-root-conformation representation/discontinuous Galerkin method for simulating viscoelastic two-phase flow systems
Authors: Ma Mengxia , Wang Xiaodong , Ouyang Jie
Published: December 2024

A new numerical method, which is based on the coupling of adaptive mesh technique, level set (LS) method, square-root-conformation representation (SRCR) approach, and discontinuous Galerkin (DG) method within the dual splitting framework, is developed for viscoelastic two-phase flow problems. This combination has been more effective than expected. The LS method is performed to capture the moving interface due to its efficiency and simplicity when dealing with the significant interface deformations. The dual splitting scheme is applied to decouple the whole system into subequations, which circumvent the limitation of the Ladyzhenskaya-Babuška-Brezzi condition. The SRCR approach is employed to reconstruct the Oldroyd-B constitutive equation to solve the high Weissenberg number problem. The high-order DG method is performed for the spatial discretizations of equations to deal with the convection-dominated problems. In addition, the reinitialization method of the LS function and a simple mass correction technique are applied to guarantee the mass conservation in calculation. In this coupled method, there is no need to require reinitialization within every time step but after suitable time steps. Meanwhile, the adaptive mesh technique is implemented in the coupling procedure, which greatly improves the computational efficiency. The coupled algorithm is performed to simulate the swirling deformation flow, Rayleigh–Taylor instability and bubble rising problems. And the influences of the parameters on the rising speed and shape of bubble in viscoelastic liquid are analyzed in detail. The numerical results indicate that the coupled algorithm is effective and accurate for simulating the interface evolution problems with complex topological structure changes, and can guarantee the mass conservation property.
Double configuration interaction singles: Scalable and size-intensive approach for orbital relaxation in excited states and bond-dissociation
Authors: Tsuchimochi Takashi
Published: December 2024

We present a novel theoretical scheme for orbital relaxation in configuration interaction singles (CIS) based on a perturbative treatment of its electronic Hessian, whose analytical derivation is also established in this work. The proposed method, which can be interpreted as a “CIS-then-CIS” scheme, variationally accounts for orbital relaxation in excited states, thus significantly reducing the overestimation of charge-transfer excitation energies commonly associated with standard CIS. In addition, by incorporating de-excitation effects from CIS, we demonstrate that our approach effectively describes single bond dissociation. Notably, all these improvements are achieved at a mean-field cost, with the pre-factor further reduced with the efficient algorithm introduced here, while preserving the size-intensive property of CIS.
Flow regimes in the evolution of a hot buoyant vortex dipole
Authors: Praveen Kumar V. , Agarwal Kanak , Sameen A. , Thara Reshma I. V.
Published: December 2024

Vortices and vortex dipoles play a critical role in turbulence, facilitating scalar mixing, diffusion, and energy dissipation. When a temperature gradient is present, buoyancy effects become significant, and buoyant vortices and dipoles emerge as characteristic features of such flows. In this study, we examine the evolution of a buoyant vortex dipole (BVD) arising from a temperature difference between the vortex dipole and the surrounding fluid. Using the Oberbeck–Boussinesq approximation, we derive the governing equations in non-dimensional form to capture the essential physics. The computational domain is periodic, and simulations are performed using the open-source spectral solver Dedalus. The interplay of thermal diffusion, viscous diffusion, and buoyancy drives the evolution of various coherent structures. Based on these interactions, we identify four distinct topological features and classify the evolution of the BVD into six regimes: (a) thermal diffusion-dominated regime, (b) viscous diffusion-dominated regime, (c) balanced diffusion regime, (d) weak wake street regime, (e) buoyancy-driven transition regime, and (f) multiple tertiary wakes regime. This classification provides a comprehensive framework to understand the dynamics of BVDs under varying physical influences.
Diffusion of impurities in a moderately dense confined granular gas
Authors: Gómez González Rubén , Garzó Vicente , Brito Ricardo , Soto Rodrigo
Published: December 2024

Mass transport of impurities immersed in a confined quasi-two-dimensional moderately dense granular gas of inelastic hard spheres is studied. The effect of the confinement on granular particles is modeled through a collisional model (the so-called Δ-model) that includes an effective mechanism to transfer the kinetic energy injected by vibration in the vertical direction to the horizontal degrees of freedom of grains. The impurity can differ in mass, diameter, inelasticity, or the energy injection at collisions, compared to the gas particles. The Enskog–Lorentz kinetic equation for the impurities is solved via the Chapman–Enskog method to first order in spatial gradients for states close to the homogeneous steady state. As usual, the three diffusion transport coefficients for tracer particles in a mixture are given in terms of the solutions of a set of coupled linear integral equations, which are solved by considering the lowest Sonine approximation. The theoretical predictions for the tracer diffusion coefficient (relating the mass flux with the gradient of the number density of tracer particles) are compared with both direct simulation Monte Carlo and molecular dynamics simulations. The agreement is in general good, except for strong inelasticity and/or large contrast of energy injection at tracer-gas collisions compared to gas-gas collisions. Finally, as an application of our results, the segregation problem induced by both a thermal gradient and gravity is exhaustively analyzed.
Unlocking n-type semiconductivity in diamond: A breakthrough approach via surface metal doping
Authors: Liu Defeng , Wu Guixuan , Luo Shulin , Wang Gangcheng , Wang Xiaowei , Wang Xueting
Published: December 2024

Device applications of ultra-wide bandgap diamond rely on controlled carrier types and concentrations, yet conventional n-type doping in diamond has been challenging due to its strong covalent bonds. Surface charge transfer doping (SCTD) provides an effective alternative, utilizing energy level differences between surface dopants and semiconductors to modulate carrier properties. In this study, we examined n-type SCTD doping on oxygen- and fluorine-passivated diamond (100) surfaces [diamond(100):Y, where Y = O, F] using alkali metals (Na, K, Rb, and Cs) through first-principle calculations. Following surface metal doping of diamond(100):Y, electron enrichment shifted the Fermi level into the conduction band, confirming effective n-type doping. The maximum areal electron densities reached 2.50 × 1014 cm−2 for diamond(100):O and 2.00 × 1014 cm−2 for diamond(100):F, exceeding the previously reported optimal values for surface organic molecule doping. For diamonds of equal thickness and identical passivating atoms, charge transfer followed the trend Na > K > Rb > Cs, inversely related to atomic radius. With increasing diamond thickness, charge transfer rose for oxygen-passivated surfaces and declined for fluorine-passivated ones before stabilizing, corresponding to the conduction band minimum (CBM) shift: downward for oxidization and upward for fluorination. For all alkali metal surface doping, charge transfer was greater in diamond(100):O than in diamond(100):F, owing to the lower CBM of oxidized diamond. Overall, effective n-type SCTD doping is critically influenced by diamond’s CBM levels—dependent on its thickness and surface passivation—and the metal atom’s radius. These findings provide theoretical insights into advancing diamond-based electronic and optoelectronic devices.
Reduced voltage-activated Ca2+ release flux in muscle fibers from a rat model of Duchenne dystrophy
Authors: Schreiber Jonathan , Rotard Ludivine , Tourneur Yves , Lafoux Aude , Berthier Christine , Allard Bruno , Huchet Corinne , Jacquemond Vincent
Published: December 2024

The potential pathogenic role of disturbed Ca2+ homeostasis in Duchenne muscular dystrophy (DMD) remains a complex, unsettled issue. We used muscle fibers isolated from 3-mo-old DMDmdx rats to further investigate the case. Most DMDmdx fibers exhibited no sign of trophic or morphology distinction as compared with WT fibers and mitochondria and t-tubule membrane networks also showed no stringent discrepancy. Under voltage clamp, values for holding current were similar in the two groups, whereas values for capacitance were larger in DMDmdx fibers, suggestive of enhanced amount of t-tubule membrane. The Ca2+ current density across the channel carried by the EC coupling voltage sensor (CaV1.1) was unchanged. The maximum rate of voltage-activated sarcoplasmic reticulum (SR) Ca2+ release was reduced by 25% in the DMDmdx fibers, with no change in voltage dependency. Imaging resting Ca2+ revealed rare spontaneous local SR Ca2+ release events with no sign of elevated activity in DMDmdx fibers. Under current clamp, DMDmdx fibers generated similar trains of action potentials as WT fibers. Results suggest that reduced peak amplitude of SR Ca2+ release is an inherent feature of this DMD model, likely contributing to muscle weakness. This occurs despite a preserved amount of releasable Ca2+ and with no change in excitability, CaV1.1 channel activity, and SR Ca2+ release at rest. Although we cannot exclude that fibers from the 3-mo-old animals do not yet display a fully developed disease phenotype, results provide limited support for pathomechanistic concepts frequently associated with DMD such as membrane fragility, excessive Ca2+ entry, or enhanced SR Ca2+ leak.
How could simulations elucidate Nav1.5 channel blockers mechanism?
Authors: Pipatpolkai Tanadet
Published: December 2024

Tao and Corry used metadynamics, an enhanced sampling method to identify and classify Nav channel blockers.
PAHs in protein matrix
Authors: Lobsiger Simon , Umbricht Gisela , Mallia Silvia , Bilsel Mine , Gökçen Taner , Akkuş Özen Şükran , Kaminski Martin , Zübner Isabella , Đokić Vasić Dragana , Bešter Erika , Valenčič Vasilij , Portesi Chiara , Schiavone Consolato , Romaniello Francesco
Published: December 2024

Main text

This Supplementary Comparison, EURAMET.QM-S15 "PAHs in Protein Matrix", was organized by the Federal Institute of Metrology METAS. The target analytes were four PAHs: benz[a]anthracene (BaA); benzo[a]pyrene (BaP); benzo[b]fluoranthene (BbF); and chrysene (Chr), for which maximum limits are set in the European and Swiss food legislation. The measurands were the mass fractions (µg/kg) of these PAHs in a protein-rich matrix.

Six National Metrology Institutions (NMIs) and Designated Institutes (DIs) participated in EURAMET.QM-S15. The study required solvent extraction, separation of the target analytes from interfering matrix components (clean-up), analytical/chromatographic separation and selective detection of the target analytes.

Solvent extraction (ASE, PLE, HUPsSE, QuEChERS) followed by SPE cleanup was applied by the participants in the sample pretreatment and GC-IDMS/MS, GC-HR-IDMS and LC-FLD were applied for separation and detection.

The results for the determination of the four PAHs in EURAMET.QM-S15 ranged from 0.5 µg/kg to 5.3 µg/kg for BaA, 0.6 µg/kg to 13.3 µg/kg for BaP, 0.6 µg/kg to 7.0 µg/kg for BbF and 0.5 µg/kg to 5.0 µg/kg for Chr.

Due to poor extraction efficiencies, as a result of unfavorable choice of solvent and insufficient demonstration of metrological traceability of the calibrant, only the results of two participants were included in the evaluation of the Supplementary Comparison Reference Value (SCRV). The SCRV was assigned using the weighted mean of these two participants which agreed well with gravimetrically prepared mass fractions and evidence from an ancillary study performed with external expert laboratories. Four participant results were excluded from the SCRV for the technical reasons mentioned above. The SCRV (X ± u(X)) was 3.291 µg/kg ± 0.079 µg/kg for BaA, 4.28 µg/kg ± 0.10 µg/kg for BaP, 4.77 µg/kg ± 0.12 µg/kg for BbF and 2.967 µg/kg ± 0.070 µg/kg for Chr. The two institutes that were included in the assignment of consensus SCRV agreed within their standard uncertainties.

Successful participation in EURAMET.QM-S15 demonstrates the following measurement capabilities in determining the mass fractions of organic compounds, with a molecular mass between 150 g/mol and 500 g/mol, having a low polarity (pKow < -2), in a mass fraction range from 0.1 µg/kg to 100 µg/kg in a high protein food matrix.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Multi-frequency compact encoding metasurface for independent beam control
Authors: Huang Xiaojun , Li Wentao , Xue Qi , Gao Junfei , Wang Danqi , Xiang Mei
Published: December 2024

Encoding metasurfaces, as innovative materials that facilitate the integration of the physical and digital realms, offer engineers a more streamlined and effective approach to manipulating electromagnetic waves. In order to modulate electromagnetic waves at multiple frequencies with a single metasurface as much as possible, researchers adopt methods such as mechanical stretching and multilayer stacking to design a variety of structures. However, these works all have problems like complex structures and inconvenience in use. Therefore, it is still a challenge to design a metasurface that can flexibly modulate electromagnetic waves at multiple frequencies by using a simple structure. In this paper, we present a reflective encoding metasurface capable of independently modulating the phase at two disparate frequencies. This is achieved through the manipulation of octagonal copper rings and copper patches on the meta-atom. To enhance and achieve more precise beam control accuracy, a genetic algorithm is utilized to optimize the arrangement of low-frequency and high-frequency structures individually, which are then integrated to facilitate beam deflection at both frequencies. The simulation results demonstrate that the proposed compact dual-frequency coded metasurface effectively controls the incident electromagnetic waves at 6 GHz and 19 GHz, and realizes the beam deflection within the range of elevation angles from 0° to 45° and azimuth angles from 0° to 360° in the half-space. Measurements are performed in a microwave anechoic chamber to verify the simulations, and the measurement results are consistent with the simulations. The proposed metasurface has potential applications in compact space and multi-channel communication services due to its good beam control capability.
Dynamics of a single anisotropic particle under various resetting protocols
Authors: Chaki Subhasish , Olsen Kristian Stølevik , Löwen Hartmut
Published: December 2024

We study analytically the dynamics of an anisotropic particle subjected to different stochastic resetting schemes in two dimensions. The Brownian motion of shape-asymmetric particles in two dimensions results in anisotropic diffusion at short times, while the late-time transport is isotropic due to rotational diffusion. We show that the presence of orientational resetting promotes the anisotropy to late times. When the spatial and orientational degrees of freedom are reset, we find that a non-trivial spatial probability distribution emerges in the steady state that is determined by the initial orientation, particle asymmetry and the resetting rate. When only spatial degrees of freedom are reset while the orientational degree of freedom is allowed to evolve freely, the steady state is independent of the particle asymmetry. When only particle orientation is reset, the late-time probability density is given by a Gaussian with an effective diffusion tensor, including off-diagonal terms, determined by the resetting rate. Generally, the coupling between the translational and rotational degrees of freedom, when combined with stochastic resetting, gives rise to unique behavior at late times not present in the case of symmetric particles. Considering recent developments in experimental implementations of resetting, our results can be useful for the control of asymmetric colloids, for example in self-assembly processes.
Chiral effects at the metal center in Fe(III) spin crossover coordination salts
Authors: Zaz M Zaid , Chin Wai Kiat , Viswan Gauthami , Subedi Arjun , Mishra Esha , McElveen Kayleigh A , Tamang Binny , Shapiro David , N’Diaye Alpha T , Lai Rebecca Y , Dowben Peter A
Published: December 2024

Evidence of chirality was observed at the Fe metal center in Fe(III) spin crossover coordination salts [Fe(qsal)2][Ni(dmit)2] and [Fe(qsal)2](TCNQ)2 from x-ray absorption (XAS) spectroscopy at the Fe 2p3/2 core threshold. Based on the circularly polarized XAS data, the x-ray natural circular dichroism for [Fe(qsal)2][Ni(dmit)2] and [Fe(qsal)2](TCNQ)2 is far stronger than seen for [Fe(qsal)2]Cl suggesting this natural circular dichroism signature is a ligand effect rather than a result of just a loss of octahedral symmetry on the Fe core. The larger the chiral effects in the Fe 2p core to bound XAS, the greater the perturbation of the Fe 2p3/2 to 2p1/2 spin–orbit splitting seen in the XAS spectra.
Application of three-dimensional point cloud technology based on spectral confocal in FPC welding inspection
Authors: Wang Tianle , Chen Fei , Chen Xiaobo , Zhu Zhisong
Published: December 2024

In response to welding quality inspection challenges in new energy vehicle battery systems, a fusion detection method based on two-dimensional (2D) and three-dimensional (3D) data is proposed. Initially, the point cloud data of the region of interest (ROI) were extracted with point cloud percentile filtering. Subsequently, the processed point cloud data were projected onto a 2D plane, and the coordinate data of the ROI was obtained by virtue of 2D image-processing techniques. This data was back-projected into a 3D space to retrieve the corresponding depth data. Finally, the depth value of the weld pit was determined by computing the vertical distance between the bottom of the weld pit and a predefined reference plane from the obtained depth data. Experimental results indicate that when detecting workpieces containing 50 valid weld pits, compared with traditional 3D detection methods, the detection time of this method is reduced from 6.70 s to 1.18 s. Additionally, the depth measurement error and variance are reduced by 39.24% and 59.46%. This method significantly improves the detection efficiency and accuracy, enabling an efficient analysis of the welding quality.
Review and novel formulae for transmittance and reflectance of wedged thin films on absorbing substrates
Authors: Ballester Manuel , Marquez Emilio , Bass John , Würsch Christoph , Willomitzer Florian , Katsaggelos Aggelos K
Published: December 2024

Historically, spectroscopic techniques have been essential for studying the optical properties of thin solid films. However, existing formulae for both normal transmission and reflection spectroscopy often rely on simplified theoretical assumptions, which may not accurately align with real-world conditions. For instance, it is common to assume (1) that the thin solid layers are deposited on completely transparent thick substrates and (2) that the film surface forms a specular plane with a relatively small wedge angle. While recent studies have addressed these assumptions separately, this work presents an integrated framework that eliminates both assumptions simultaneously. In addition, the current work presents a deep review of various formulae from the literature, each with their corresponding levels of complexity. Our review analysis highlights a critical trade-off between computational complexity and expression accuracy, where the newly developed formulae offer enhanced accuracy at the expense of increased computational time. Our user-friendly code, which includes several classical transmittance and reflectance formulae from the literature and our newly proposed expressions, is publicly available in both Python and Matlab at this link.
Electrochemical deposition of Ni on arrays of GaAs nanowires with n-type channels
Authors: Kuzmin V , Mokhov D , Berezovskaya T , Monastyrenko A , Bouravleuv A
Published: December 2024

The processes of electrochemical deposition of Ni on vertically aligned GaAs nanowires (NWs) grown by molecular-beam epitaxy (MBE) using Au as a growth catalyst on n-type Si(111) substrates were studied. Based on the results of electrochemical deposition, it was concluded that during the MBE synthesis of NWs the self-induced formation of conductive channels can occur inside NWs, thereby forming quasi core–shell NWs. Depending on the length of the channel compare to the NW heights and the parameters of electrochemical deposition, the different hybrid metal-semiconductor nanostructures, such as Ni nanoparticles on GaAs NW side walls, Ni clusters on top ends of GaAs NWs, core–shell GaAs/Ni NWs, were obtained.
Singular solutions for the conformal Dirac–Einstein problem on the sphere
Authors: Maalaoui Ali , Martino Vittorio , Xu Tian
Published: December 2024

In this paper we investigate the existence of singular solutions to the conformal Dirac–Einstein system. Because of its conformal invariance, there are many similarities with the classical construction of singular solutions for the Yamabe problem. We construct here a family of singular solutions, on the three dimensional sphere, having exactly two singularities.
Structural damage diagnosis of a cable-stayed bridge based on VGG-19 networks and Markov transition field: numerical and experimental study
Authors: Lu Naiwei , Liu Zengyifan , Cui Jian , Hu Lian , Xiao Xiangyuan , Liu Yiru
Published: December 2024

Traditional physical-driven modal methods are inappropriate for damage diagnosis of long-span flexible structures with complex mechanical behaviour. This study develops a deep Convolutional Neural Network-based damage diagnosis method for in-service bridges by using dynamic responses under moving loads. The dynamic responses were collected from the critical points on the girders of a cable-stayed bridge specimen under vehicle loading. These collected data was transformed into images based on Gramian Angular Field and Markov Transition Field (MTF). A deep learning algorithm based on VGG-19 was used to extract the damage feature from the data images associated with the structural responses. Finally, the unlabelled vibration data were input into the VGG-19 model for structural damage diagnosis. An experimental study was conducted for the damage diagnosis of a scale specimen of a cable-stayed bridge under moving loads. The acceleration signals of the main girder of the cable-stayed bridge under several damage conditions were monitored. The numerical results show the training accuracy of the deep learning method based on VGG-19 with MTF is up to 88%, and the average accuracy of the test dataset is 86.46% for each classification label. The transfer learning method can increase the classification accuracy up to 97.89%, indicating the advantage of intergrating transfer learning and VGG-19 network for structural damage diagnosis. The combination of VGG-19 and MTF algorithm provides a better solution for structural damage diagnosis of in-service infrastructures with long-term monitoring data.
HAIL: a family of high-diffusion lightweight block ciphers for internet of things security
Authors: Deng ChuTian , Li Lang , Feng JiaYi , Yan LiuYan
Published: December 2024

The accelerated evolution of Internet of Things (IoT) technology has made it crucial to secure information from resource-constrained devices. Therefore, a high-diffusion lightweight block cipher family, called HAIL, is proposed in this work to provide higher security for IoT devices while minimizing area and power consumption. In more detail, HAIL constructs an improved Lai-Massey structure with the high diffusion of the SPN structure and the symmetry of the Feistel structure. Additionally, the differential probability of 1 in the Lai-Massey structure is successfully avoided by introducing additional nonlinear operations. Compared to traditional ciphers employing the Lai-Massey structure, HAIL significantly reduces area consumption by discarding the modular component and adding shift operations into the Lai-Massey branch, thereby enhancing security. Moreover, HAIL selects an involutive, low-area S-box using Genetic Programming (GP) and combines it with an S-box that exhibits strong side-channel resistance, making the nonlinear part of HAIL advantageous for side-channel protection. Detailed testing verifies that HAIL64 and HAIL128 achieve full diffusion and avalanche effect within one and three rounds, respectively, showcasing effective diffusion properties. The throughput-to-area ratios of HAIL64 and HAIL128 at 100 kHz are 0.202 and 0.234 (SMIC 0.18 μm) respectively. Experimental results indicate that HAIL is immune to both linear and differential cryptanalysis. Finally, HAIL demonstrates high security redundancy against impossible differential attacks and Meet-In-The-Middle (MITM) attacks, among others, while its low power and area requirements address critical IoT constraints.
Modified Klein–Gordon oscillator in Ellis-Bronnikov-type wormhole spacetime with cosmic string and global monopole
Authors: de Oliveira M D , Schmidt Alexandre G M
Published: December 2024

In this paper, we investigate the modified relativistic oscillator with the Cornell potential via the quadri-potential given by X

μ
 = (0, mωr + A/r, 0, 0) in the Ellis-Bronnikov-type wormhole spacetime with a global monopole and a cosmic string. We obtain the angular and radial wave functions exactly, as well as the eigenenergies. The radial wave function is expressed in terms of Heun polynomials, involving the quantum number n and the eigenenergies. By setting the value of n incrementally, the oscillation frequency ω is quantized with respect to l and m. Finally, as an example, we analyze the ground state and graphically investigate the influence of the global monopole, cosmic string, and A on the oscillator frequency, eigenenergies, and radial probability density, as well as the effect of the wormhole curvature on the radial probability density.
Dynamical insights into bifurcation, chaos and solitons in the space-time fractional symmetric regularized long wave equation
Authors: Younas Tayyaba , Ahmad Jamshad
Published: December 2024

The nonlinear conformable time-fractional Symmetric Regularized Long Wave (SRLW) equation is a significant model in physics, particularly for describing ion acoustic and space charge waves with weak nonlinearity. In this study, we apply the modified Sardar sub equation method and the modified extended auxiliary equation method to solve the SRLW equation. We effectively manage the fractional derivatives in the equation by employing Jumarie’s modified Riemann-Liouville derivative. Various types of soliton solutions, including kink, periodic, dark, bright, and singular solitary waves, are obtained in forms such as rational, hyperbolic, trigonometric, and exponential functions. A comparative analysis of the methods and the results is conducted, along with an exploration of fractional derivative effects by varying their values. The study also includes 2D and 3D plots that show how the solutions behave over time. It demonstrates that the methods used can be applied to other nonlinear models in mathematical physics. The research looks closely at the model’s behavior, including bifurcation, chaos, and stability. Phase portrait analysis at key points shows changes in the system’s behavior, and adding an external periodic force leads to chaotic patterns. The stability analysis proves that these methodsare reliable for studying phase portraits and soliton solutions in different nonlinear systems.
Role of oxygen vacancies in improving the NO gas sensing behavior of DC magnetron sputtered sub-stoichiometric WO3 thin films
Authors: Dwivedi Charu , Srivastava Stuti , Kumar Ashwani , Singh Preetam
Published: December 2024

WO3 thin films have been deposited on alumina substrates at different O2/Ar gas ratios and thicknesses by reactive DC magnetron sputtering for NO gas sensing. X-ray photoelectron spectroscopy (XPS) confirms the presence of oxygen vacancies in all monoclinic-phase WO3 thin films. A systematic decrease in the band gap was found with an increase in the oxygen vacancies leading to a significant upward shift in the Fermi level. Here, the influence of stoichiometry of WO3 thin film on the NO gas sensing performance is presented. It was found that the fabricated device using sub-stoichiometric WO3−x showed enhanced performance in terms of high stability, high selectivity, and fast response/recovery time with a sensor response of 147 for 50 ppm NO concentration at 275 °C, with a fast response time (∼19 s) and recovery time (∼17 s). The NO gas sensing of WO3 thin films has been tested at different operating temperatures (175–350 °C) and gas concentrations (1–50 ppm), witnessing a variation in sensor response. The NO gas sensing mechanism on the surface of WO3 has also been discussed.
A framework to obtain wave, energy, and momentum conservation equations
Authors: Aldakhail Allah Amal S , Arbab Arbab I
Published: December 2024

A new method for obtaining wave, energy, and momentum conservation equations for Dirac and Maxwell systems is presented. This method makes use of the algebraic features of quaternion products. A framework that uses quaternions to describe quantum physics and electrodynamics has been introduced. In this approach, mass and charge produce electric and magnetic fields that satisfy Maxwell's equations. Quaternionic mass leads to massive electrodynamics based on quantum mechanics concepts. The conservation of energy and momentum is not affected by quaternionic mass. Quaternionic Maxwell's equations with quaternionic mass yield intriguing phenomena that can be examined experimentally. These equations generalize the classical Wilczek axion electrodynamics to quantum one.
Generating immiscible localized WC phase in layered WS2 upon 15 keV C2+ irradiation
Authors: Deka Bhupali , Talukdar Dhanjit , Naik V , Saha A , Mohanta D
Published: December 2024

Herein, we report on the insertion of tungsten carbide (WC) phase within tungsten disulfide (WS2) nanosheets taking advantage of the combinatorial effects of implantation of C with low energy irradiation of 15 keV C2+ ions and generating sulfur vacancies. The x-ray diffraction (XRD) analyses suggest the co-existence of WC and WS2 hexagonal phases at mid-fluences of ion implantation, typically in the range of 3.5 × 1015 – 7.5 × 1015 ions cm−2. The phase analysis revealed that WC content was highest at a fluence of 3.5 × 1015 ions cm−2 with ion irradiation of competing electronic (inelastic) and nuclear (elastic) energy losses. The defect-mediated peak can be probed in the Raman spectra, which is the result of numerous point defects (specifically, S vacancies and C as dopants) caused due to the ion irradiation event. First-principles calculations have also been carried out to study the geometrical constructs and electronic structures of WS2 before and after implantation. The doped C atoms in WS2 introduce localized defect states in the conduction band with minima at the M point of the Brillouin zone. Interestingly, the model predicts a semi-metallic behavior, especially when C and S vacancies tend to co-exist. Generating an immiscible WC phase within a few layered WS2 sheets is believed to enhance both the mechanical strength and stability of the specimen apart from the introduction of semi-metallicity needed for desired applications.
Synthesis, microstructural refinement, and shielding optimization of Gd2O3-reinforced AISI 316L stainless steel: a multi-dimensional integration assessment for targeted protection applications
Authors: Yayla Nihal , Albayrak M Gökhan , Guler Omer , Sen Baykal Duygu , Alkarrani Hessa , Ghada ALMisned , Issa Bashar , Tekin Huseyin Ozan O.
Published: December 2024

This study investigates the multi-dimensional effects of increasing Gd2O3 reinforcement on the structural, mechanical, and gamma-ray shielding properties of AISI 316L stainless steel composites. Samples with varying Gd2O3 content (1%, 5%, 10%, and 20% by weight) were synthesized and characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) to assess the microstructural changes and homogeneity of Gd2O3 dispersion after mechanical milling. The addition of Gd2O3 significantly enhanced the gamma-ray shielding properties, with the mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), and half-value layer (HVL) improving as the Gd2O3 content increased, particularly in low to moderate photon energy ranges. Simultaneously, the elastic modulus exhibited an inverse relationship, decreasing with higher Gd2O3 content due to the lower stiffness of gadolinium compared to iron. Transmission factor (TF) values also decreased, indicating enhanced photon attenuation with higher Gd2O3 content across various thicknesses. The experimental characterization confirmed improved Gd2O3 dispersion and material uniformity after mechanical milling, contributing to the composites' superior radiation shielding performance. It can be concluded that Gd2O3-reinforced AISI 316L stainless steel composites offer a promising balance between enhanced radiation shielding properties and reduced mechanical stiffness, making them ideal candidates for applications requiring efficient and adaptable radiation protection especially for portable and non-structural shielding applications.
A new 2D hyperchaotic model-based encryption strategy for multiple images via pixel fusion
Authors: Zhou Lili , Chen Pengyu , Tan Fei
Published: December 2024

In view of the intrinsic characteristics of chaotic system, it can be widely applied in image encryption. Considering the common issues of insufficient chaotic performance and discontinuous range of control parameters in current chaotic systems, a hybrid chaotic model with the characteristics of simple and easy to design is devised to address these challenges. Through phase portraits, bifurcation diagrams, and the analysis of Lyapunov exponent spectrum, it is demonstrated that the proposed system can exhibit robust traversal performance. To meet the demands of digital image encryption, an effective encryption strategy for multi-image based on this model is proposed, which can accommodate the varying image sizes and types simultaneously. In the given strategy, the pixels are merged from multiple images at first, and then the keys can be derived with SHA-512. By the application of discrete wavelet transform, the information can be embedded from the plaintext images, which can ensure the robust resistance to data loss while facilitating the shared transmission of plaintext information. Finally, by leveraging the developed chaotic system, a three-dimensional cross-plane scrambling and diffusion algorithm is introduced to enhance the effectiveness of encryption scheme.
Trap sensitivity of junction and junction-less nano sheet FETs: a comparative study
Authors: Gogoi Manosh Protim , Saha Rajesh , Baishya Srimanta
Published: December 2024

In this paper, we have explored the trap sensitivity of Junction and Junctionless mode Nanosheet FETs (NSFETs) using a technology computer-aided design (TCAD) simulator. The study investigates ideal trap charges at the oxide-semiconductor interface for both donor-like and acceptor-like traps. Sensitivity to variations in temperature, trap concentration, work function of gate metal, and peak energy position is analyzed and compared for both types of NSFETs. The findings indicate that the sensitivity of Junction NSFETs to various electrical parameters is significantly higher than Junctionless NSFETs. Specifically, Junction NSFET shows sensitivities of around 100 and 77 for acceptor and donor impurities, respectively, while the Junctionless NSFET exhibits sensitivities of approximately 100 and 62 for acceptor and donor impurities, respectively, across a wide range of trap concentration variations. Furthermore, even with large fluctuations in the parameters, the trap sensitivity at high gate voltage is insignificant for donor-type trap concentrations. For changes in peak energy position the junction mode offers sensitivity of about 70.1 and 35 for acceptor and donor traps, respectively, while junctionless mode shows sensitivity of about 33.69 and 23 for acceptor and donor traps, respectively.
A hybrid network using transformer with modified locally linear embedding and sliding window convolution for EEG decoding
Authors: Li Ketong , Chen Peng , Chen Qian , Li Xiangyun
Published: December 2024

Objective. Brain–computer interface(BCI) is leveraged by artificial intelligence in EEG signal decoding, which makes it possible to become a new means of human-machine interaction. However, the performance of current EEG decoding methods is still insufficient for clinical applications because of inadequate EEG information extraction and limited computational resources in hospitals. This paper introduces a hybrid network that employs a transformer with modified locally linear embedding and sliding window convolution for EEG decoding. Approach. This network separately extracts channel and temporal features from EEG signals, subsequently fusing these features using a cross-attention mechanism. Simultaneously, manifold learning is employed to lower the computational burden of the model by mapping the high-dimensional EEG data to a low-dimensional space by its dimension reduction function. Main results. The proposed model achieves accuracy rates of 84.44%, 94.96%, and 82.79% on the BCI Competition IV dataset 2a, high gamma dataset, and a self-constructed motor imagery (MI) dataset from the left and right hand fist-clenching tests respectively. The results indicate our model outperforms the baseline models by EEG-channel transformer with dimension-reduced EEG data and window attention with sliding window convolution. Additionally, to enhance the interpretability of the model, features preceding the temporal feature extraction network were visualized. This visualization promotes the understanding of how the model prefers task-related channels. Significance. The transformer-based method makes the MI-EEG decoding more practical for further clinical applications.