bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal operation control strategy for off-grid photovoltaic hydrogen production system considering hydrogen production efficiency
Authors: Pan Lei , Chen Liang , Pang Yi , Chen Jianwei , Shi Fan , Li Rui , Liang Yin
Published: December 2024

Off-grid photovoltaic hydrogen production is an effective solution for improving photovoltaic (PV) utilization and obtaining green hydrogen. The main challenge faced by off-grid photovoltaic hydrogen production systems (OGPHPS) is how to deal with the randomness, intermittency, and volatility of PV generation. Therefore, this paper proposes an optimal operation control strategy (OOCS). First, a model of OGPHPS is established, comprising photovoltaics, batteries, and an electrolytic array (ELA). Second, a two-step optimization strategy (TSOS) that integrates both long-term and short-term time scales is proposed. In the first step of TSOS, the day-ahead optimization of the operation state of ELA is conducted according to day-ahead power prediction. A constraint was proposed to balance the operation time of the electrolyzer. In the second step of TSOS, according to the ultra-short time power prediction and the electrolyzer efficiency curve, the rolling optimization of the operating power distribution of ELA is carried out. Through TSOS, PV generation consumption is maximized by ELA, the continuous operational stability of OGPHPS is enhanced, and the lifespan of electrolyzer is extended. Third, to alleviate the influence of instantaneous power fluctuation on the system, an energy management strategy (EMS) for OGPHPS is proposed. Finally, a simulation model of OGPHPS was established, and the simulation results showed that the direct current bus voltage fluctuation was within 3%. Compared to the chain allocation strategy, the OOCS achieves higher hydrogen production under the same solar irradiance conditions. Particularly in low irradiance, OOCS has more sufficient consumption of PV generation and higher hydrogen production efficiency.
Numerical simulation of CuCr alloys vacuum arc under conditions of arc contraction, deflection, and anode vapor
Authors: Wang Lijun , Wang Xiangyu , Chen Jieli , Luo Ming , Xie Yiduo , Wang Hongjian
Published: December 2024

In practical arc ignition processes of high-current vacuum arcs, despite the calibration effect of the axial magnetic field, the strong magnetic constriction force still causes the arc to contract. Additionally, during the actual electrode opening process, due to the random nature of the arcing position, the center of the arc column is often not located at the center of the electrode. At this point, the behavior of the vacuum arc can be understood as an asymmetric three-dimensional (3D) process under the influence of the spatial magnetic field, affecting the generation of anode vapor and the characteristics of arc species. Therefore, it is useful to conduct simulation studies on multi-species vacuum arc behavior considering arc contraction and arc deflection. In this paper, the spatial magnetic field distribution under different electrode effective areas and different arc center deflection distances have been simulated, and the influence of actual magnetic field-induced by arc contraction and deflection on 3D spatial distribution characteristics of arc plasma has been studied based on a 3D multi-species (CuCr alloys) vacuum arc model with anode vapor. The simulation results show that with the contraction of the arc column, the area occupied by neutral atomic vapor decreases correspondingly, but the ionization and recombination process between the arc column regions becomes more intense. The axial current density and electron temperature distribution around the neutral atomic vapor area become more non-uniform. When the arc column deviates from electrode center, the neutral atomic vapor area shows an asymmetrical distribution on both sides of the arc column center axis, and the axial current density and electron temperature gather and enhance in the opposite direction of the arc deflection, thereby significantly affecting the distribution of arc species.
Speckle-based 3D sub-diffraction imaging of sparse samples through a multimode fiber
Authors: Lyu Zhouping , Hung Shih-Te , Smith Carlas S. , Amitonova Lyubov V.
Published: December 2024

A flexible multimode fiber is an exceptionally efficient tool for in vivo deep tissue imaging. Recent advances in compressive multimode fiber sensing allow for imaging with sub-diffraction spatial resolution and sub-Nyquist speed. At present, the technology is limited to imaging in a two-dimensional (2D) plane near the fiber distal facet, while in real applications it is very important to visualize three-dimensional (3D) structures. Here, we propose a new approach for fast sub-diffraction 3D imaging of sparse samples through a multimode fiber by using a single 2D scan, speckle illumination, and bucket detection. We experimentally demonstrate precise image plane location as well as 3D imaging of samples with various scattering coefficients. The full width at half maximum of the point spread function along the axial direction is three times smaller than the diffraction limit. Our study grants depth-resolving capacity to ultra-thin super-resolution fiber endoscopes for life science and medical applications.
A PINN framework for inverse physical design of metal-loaded electromagnetic devices
Authors: Liu Yu-Hang , Liu Jin-Pin , Wang Bing-Zhong , Wang Ren
Published: December 2024

To solve the difficulty of inverse design of metal-loaded electromagnetic devices, we propose a physics-informed neural network (PINN) framework. With the emergence of PINNs, some scholars within the field of electromagnetism have utilized them to design dielectric-loaded electromagnetic devices. However, using PINN to design metal-loaded electromagnetic devices is still uncommon due to the difficulty of binarization of metal shapes. In light of this, we propose a PINN framework to address the inverse physical design of metal-loaded electromagnetic devices. In PINN, we embed mathematical-physics models into the network, which endows the training parameters of PINN with practical physical significance. The main innovation of this paper is to solve the binarization problem in the inverse design of metal-loaded devices within the PINN. To verify the feasibility of our method, we provide an example of designing a dual-layer metal diaphragm-loaded parallel plate waveguide device. The PINN presented with metal binarization in this paper offers a novel approach to the inverse physical design of metal-loaded electromagnetic devices.
Fast–slow analysis and bifurcations in the generation of the early afterdepolarization phenomenon in a realistic mathematical human ventricular myocyte model
Authors: Kitajima Hiroyuki , Yazawa Toru , Barrio Roberto
Published: December 2024

Early afterdepolarizations (EADs) are spontaneous oscillations in membrane potential that occur during the repolarization phase of the action potential. EADs can trigger ventricular arrhythmias, such as Torsades de Pointes, in patients with long QT syndromes. Understanding the theoretical mechanisms behind EAD generation and developing strategies to suppress them are crucial. In this study, we employed bifurcation analysis along with a new fast–slow decomposition method on the O’Hara model of human ventricular myocytes. Our goal was to examine how the calcium ion concentration in the network sarcoplasmic reticulum (NSR) influences the generation of EADs in the context of reduced rapid delayed rectifier K+ current. Our findings identified nine distinct EAD states that coexist and can be controlled by slight adjustments to the NSR calcium ion concentration at a single time point.
Two-dimensional optical binding based on graphene surface plasmon excitation
Authors: Ferrari H. , Cuevas M.
Published: December 2024

In this work, we present a detailed analysis of the optical binding force resulting from the near field scattering between dielectric nanoparticles and a graphene substrate. We pay special attention to the two-dimensional array formation for which the stability is raised owing to the multiple surface plasmon (SP) scattering. Because of the small values of the SP wavelength on graphene in comparison with those of the photon, the size of these particle arrangements falls below the diffraction limit. By using a rigorous formalism based on the electromagnetic Green theory, we calculate the binding energy potential whose depth quantifies the stability of such configurations. We find multiple configurations for a given number of nanoparticles, from which only a subset of them remains stable under thermal fluctuations. Our contribution can be valuable for understanding the formation of new optically reconfigurable polaritonic materials.
Transition of synchronization state during the quasiperiodic route to chaos in coupled friction-induced continuous oscillators
Authors: Velayudhan Jithin , Narayanan M. D. , Saha Ashesh
Published: December 2024

Friction-induced vibration, particularly associated with the squealing problem in disk brake systems, has been a longstanding challenge in the automotive industry. In our research, we employed the synchronization theory to gain insights into the interaction between two coupled cantilever beams attached with tip masses. This proposed model emulates the dynamics of a mountain bike disk brake assembly. The work explores a range of collective behaviors, including synchronized periodic, multi-periodic, quasiperiodic, as well as desynchronized chaotic and quasiperiodic oscillations. Despite numerous studies reported on the synchronization phenomenon in discrete friction-induced oscillatory systems, there appears to be a lack of similar research on continuous systems. This work stands as the first of its kind in exploring the dynamics of synchronization between two coupled continuous systems exhibiting a quasiperiodic route to chaos. A bifurcation study is conducted utilizing the Poincaré points corresponding to the local maxima of oscillation amplitude with respect to the zero-velocity crossing. The results showed the existence of narrow multi-periodic windows during the quasiperiodic route at several locations. Additionally, the existence of multiple quasiperiodic attractors exhibiting different states of synchronization for the same set of parameters is observed. We analyzed the time evolution of the cumulative instantaneous phase difference between the coupled signals and identified distinct states of synchronization possessed by the system. The coupled system undergoes interesting phenomena such as complete phase lock, intermittent phase lock, and phase drifting. Moreover, the transition occurring to the state of synchronization during the quasiperiodic route to chaos is studied employing the phase locking value, the Pearson linear correlation coefficient, and the relative mean frequency. Notably, our findings revealed that while the Pearson correlation can effectively identify both the mode and strength of synchronization, other measures such as phase lock value and relative mean frequency only reflect synchronization strength.
The nature of the hydrophobic interaction varies as the solute size increases from methane’s to C60’s
Authors: Naito Hidefumi , Sumi Tomonari , Koga Kenichiro
Published: December 2024

The hydrophobic interaction, often combined with the hydrophilic or ionic interactions, makes the behavior of aqueous solutions very rich and plays an important role in biological systems. Theoretical and computer simulation studies have shown that the water-mediated force depends strongly on the size and other chemical properties of the solute, but how it changes with these factors remains unclear. We report here a computer simulation study that illustrates how the hydrophobic pair interaction and the entropic and enthalpic terms change with the solute size when the solute–solvent weak attractive interaction is unchanged with the solute size. The nature of the hydrophobic interaction changes qualitatively as the solute size increases from that of methane to that of fullerene. The potential of mean force between small solutes has several well-defined extrema, including the third minimum, whereas the potential of mean force between large solutes has the deep contact minimum and the large free-energy barrier between the contact and the water-bilayer separated configurations. The difference in the potential of mean force is related to the differences in the water density, energy, and hydrogen bond number distributions in the vicinity of the pairs of hydrophobic solutes.
Density corrugation due to beating of two modes of a quasi-electrostatic wave near the upper hybrid resonance
Authors: Popov A. Yu.
Published: December 2024

The effect of beating of two modes of a quasi-electrostatic wave near the linear-mode conversion point in magnetized plasmas is analyzed in the kinetic approximation. It is shown that the effect is accompanied by spatial modulation and corrugation of the plasma density profile.
Thermophysical properties of undercooled Zr–Fe–Nb alloys investigated by electrostatic levitation and molecular dynamics calculation
Authors: Zuo D. D. , Chang J. , Liu D. N. , Liao H. , Wang H. P.
Published: December 2024

The density, surface tension, and viscosity of liquid Zr76.0−xFe24.0Nbx (x = 6.6, 10.0, 15.0) alloys were measured by using the electrostatic levitation technique. The maximum undercooling achieved for these alloys was 151, 91, and 119 K, respectively. To evaluate the thermophysical properties in a wider temperature range, molecular dynamics simulations were performed by using the embedded atom method potential. Both measured and simulated results indicate that the liquid density increases linearly with decreasing temperature and also gradually rises with increasing Nb content. Additionally, the simulated and experimental results for surface tension and viscosity were analyzed. In all three alloys, surface tension increases linearly with decreasing temperature. The relationship between viscosity and temperature follows an Arrhenius-type equation, with both surface tension and viscosity increasing as the Nb content increases. The calculated results of density, surface tension, and viscosity are in good agreement with the experimental results. Furthermore, the specific heat, emissivity, and diffusion coefficient of liquid alloys were calculated. The specific heat for liquid Zr76.0−xFe24.0Nbx (x = 6.6, 10.0, 15.0) alloys is (36.47 ± 1.68), (35.20 ± 2.28), and (41.04 ± 3.73) J mol−1 K−1, respectively. Emissivity decreases linearly with temperature. The diffusion coefficient decreases, while the diffusion activation energy increases with a higher Nb content.
Hydrodynamic characteristics of cavity fluctuation behind a cone-rod assembly entering water
Authors: Zhang Q. , Yu J. C. , Huang Y. , Sun T. Z. , Zong Z.
Published: December 2024

This study explores the phenomenon of cavity fluctuation occurring behind a cone entering water at a constant velocity. The current simulations reveal that cavity fluctuations arise following deep pinch-off, leading to pronounced pressure oscillations in both the water and air regions. Concurrently, ripples form along the cavity surface, extending from the nose to the tail, resulting in a wavy cylindrical cavity. Notably, when the water entry Froude number is below 10, the load on the cone is predominantly due to pressure oscillations induced by cavity fluctuations, which exceed the slamming load experienced during initial water impact. The study also identifies a significant impact of an attached rod on cavity evolution. Specifically, the frequency of cavity rippling increases with the rod's radius; however, when the rod-to-cone radius ratio is less than 20%, the rod's impact on the cavity dynamics becomes negligible. A theoretical analysis, modeling the cavity as a hollow cylindrical structure, is developed to elucidate the relationship between rippling frequency and rod size. The research results demonstrate that the cavity fluctuation frequency is inversely proportional to the difference in the squared radii of the cone and rod. Furthermore, when the scaling length of the cavity at the pinch-off moment exceeds a ratio of Lp/Rc > 6, the water entry cavity can be accurately modeled as a long cylindrical cavity. The numerical results confirm that the proposed theoretical model provides reliable predictions of the impact of a solid rod on the fluctuation characteristics of the cavity.
High-performance full-etched fiber-to-chip grating couplers at 3.7-micron wavelength on silicon
Authors: Yang Guojiang , Xiang Hengtai , Li Zhicheng , Yu Laiwen , Li Yuanrong , Zhao Yuqi , Zhang Guowu , Guo Jingshu , Shi Yaocheng , Dai Daoxin
Published: December 2024

Mid-infrared (MIR) silicon photonics have attracted great interest for potential applications in on-chip spectroscopy, free-space communication, and remote imaging. Currently, the high-performance and fabrication-friendly fiber-to-chip grating couplers operating at 3–4 μm wavelength band are still desired urgently. Here, we propose an efficient method for designing a 2D subwavelength grating coupler. The few analytical fitting parameters defining the subwavelength grating periods and fill factors in two dimensions enable a high design degree of freedom and a low search space dimension, resulting in high figure-of-merit and fast convergence simultaneously. The developed 3.7 μm grating coupler showcases record-high coupling efficiency both theoretically (−2.2 dB) and experimentally (−4.4 dB) among the 3–4 μm MIR counterparts. This study provides an effective method for designing fiber-to-chip grating couplers, by which the MIR grating couplers with high performance and fabrication ease are developed, thus paving the way for developing high-performance silicon photonic integrated circuits operating in the MIR wavelength band.
Rheology of polyacrylamide-based fluids and its impact on proppant transport in hydraulic fractures
Authors: Kwiatkowski A. L. , Makarova (Aleshina) A. L. , Ospennikov A. S. , Shibaev A. V. , Boronin S. A. , Strizhnev G. K. , Osiptsov A. A. , Shvets P. V. , Shel E. V. , Paderin G. V. , Philippova O. E.
Published: December 2024

Rheological experiments and measurements of particle settling velocity under static conditions were conducted for two types of polyacrylamide (PAA-based) fluids. The flow behavior of the viscoelastic fluids is described by a simplified, three-parameter model that integrates a constant viscosity at low shear rates with a power-law viscosity dependency at higher shear rates. The estimated dependencies of the rheological parameters and particle settling velocity on PAA concentration align with the classical power-law scaling for semi-dilute polymer solutions. The identified scaling offers valuable insight for optimizing the chemical composition of fracturing fluids, thereby improving the efficiency of hydraulic fracturing technology. By applying the lubrication approximation to the Navier–Stokes equations, a set of equations for the suspension flow in a vertical plane channel, characterized by the three-parameter rheology model, was derived. In typical fracturing conditions, the conventional power-law viscosity model used in current fracturing simulators significantly overestimates the gap-averaged apparent fluid viscosity compared to the proposed model. The novel model of the suspension flow aims to enhance the accuracy of proppant transport models applied in hydraulic fracturing simulators. Based on the three-parameter rheology model, a new model of particle settling in the studied PAA-based fluids is developed. It is based on smart Stokes' law, where viscosity is calculated according to either the plateau or power-law region, depending on the self-induced shear rate. The new model more accurately approximates experimentally determined settling velocity of proppant under static conditions across a broad range of PAA concentrations than existing models.
Ptychographic estimation of pure multiqubit states in a quantum device
Authors: Alves Warley M. S. , Neves Leonardo
Published: December 2024

Quantum ptychography is a method for estimating an unknown pure quantum state by subjecting it to overlapping projections, each one followed by a projective measurement on a single prescribed basis. Here, we present a comprehensive study of this method applied for estimating n-qubit states in a circuit-based quantum computer, including numerical simulations and experiments carried out on an IBM superconducting quantum processor. The intermediate projections are implemented through Pauli measurements on one qubit at a time, which sets the number of ptychographic circuits to 3n (in contrast to the 3n circuits for standard Pauli tomography); the final projective measurement in the computational basis is preceded by the quantum Fourier transform (QFT). Due to the large depth and number of two-qubit gates of the QFT circuit, which is unsuitable for noisy devices, we also test the approximate QFT (AQFT) and separable unitary operations. Using the QFT and AQFT of degree 2, we obtained high estimation fidelities in all tests with separable and entangled states for up to three and four qubits, respectively; on the other hand, the separable unitaries in this scenario provided good estimations only for separable states, in general. Our results compare favorably with recent results in the literature, and we discuss further alternatives to make the ptychographic method scalable for the current noisy devices.
3D phononic Stiefel–Whitney insulator: A case study of 3D 3,42T32-type carbon allotrope (3,42T32-CA)
Authors: Li Yang
Published: December 2024

The Stiefel–Whitney (SW) insulator, a specific example of a higher-order topological insulator, is supported by spatial and time-reversal (PT) symmetry. This system with a vanishing Chern number exhibits a topology that belongs to the second SW class. Although the identification of SW insulators has been extensively suggested for 2D phononic systems in the past three years, other researchers have not given much consideration to 3D phononic systems with the SW topology. This work shows that a 3D 3,42T32-type carbon allotrope (named 3,42T32-CA) is a candidate material to host the phononic SW topology. Moreover, we present a nontrivial second SW number, represented as w2 = 1, to characterize the phononic SW topology for 3D 3,42T32-CA. Finally, we show that the 3D 3,42T32-CA hosts unconventional bulk-boundary correspondence, i.e., it exhibits 1D hinge vibrational modes in two dimensions lower than the 3D bulk vibrational modes.
MRSimulator: A cross-platform, object-oriented software package for rapid solid-state NMR spectral simulation and analysis
Authors: Srivastava Deepansh J. , Giammar Matthew , Venetos Maxwell C. , McCarthy-Carney Lexi , Grandinetti Philip J.
Published: December 2024

The open-source Python package, MRSimulator, is presented as a simple-to-use, fast, versatile, and extendable package capable of simulating one- and higher-dimensional Nuclear Magnetic Resonance (NMR) spectra under static, magic-angle, and variable-angle conditions. High benchmarks in spectral simulations are achieved by assuming that there are no degeneracies in the energy eigenstates, i.e., all dipolar couplings are in the weak limit and that there are no rotational resonances during evolution periods. Under these assumptions, the symmetry pathway formalism is exploited to reduce an NMR method applied to a spin system into a sum of individual transition pathways, whose signals are more efficiently calculated individually than as part of a full-density matrix simulation. To increase numerical efficiencies further, our approach restricts coherence transfer among transitions to pure rotations about an axis in the x–y plane of the rotating frame or through an artificial total mixing operation between selected transitions of adjacent free evolution periods. The assumptions used in this approach are valid for most commonly used solid-state NMR methods. Details of the implementation, along with example code usage, are given, including a least-squares spectral analysis.
A review on magnetic permeability in heat and fluid flow characteristics: Applications in magnetized shielding
Authors: Nabwey Hossam A. , Ashraf Muhammad , Rashad A. M. , Chamkha Ali J.
Published: December 2024

Magnetic permeability as a material property has a significant impact on the characteristics of a heated surface where induction heating or magneto-thermal systems are involved. In the heat and fluid flow mechanism where heat induction is used, magnetic permeability has a significant and crucial impact. Materials-like ferromagnetic materials with high magnetic permeability enhance the eddy current formation and can concentrate the magnetic field during the processes. These eddy currents lead to Joule heating in terms of electric current induced within the conductor by a changing magnetic field. Magnetic permeability also impacts the temperature profile within the material. Materials with extraordinary permeability due to the concentration of magnetic field can cause localized heating. The variable material properties in the presence of localized heating lead to non-uniform temperature distribution throughout the medium. In the magnetohydrodynamics heat and fluid flow region in the presence of magnetic permeability, some materials perform magnetostrictive impacts; therefore, they change shape or size under the influence of a magnetic field. The role of magnetic permeability along the heated surface is multifaceted in the system where an electromagnetic field is involved and affects how heat is generated, distributed, and dissipated. It is pertinent to mention that in the system where the electromagnetic field is involved, the magnetic permeability directly impacts the efficiency and uniform heating. Therefore, the understanding and controlling of magnetic permeability is important to design the systems that rely on exact thermal management, such as in magnetic shielding, magneto-thermal devices, and induction heating.
Optimization of hub geometry of a double suction pump as a turbine
Authors: Yang Sun Sheng , Liu Shuai Yi , Singh Punit , Zhou Ling
Published: December 2024

The double suction pump as a turbine plays an increasingly important role in energy recovery and hydropower generation due to its stable operation and simple structure. Therefore, optimization research on it is of great significance. In this article, the unique design of the hub structure in double suction pumps consisting of conventional half hubs is proposed to be modified to extend the hub until the outer diameter and analyzed. Numerical calculations based on the shear stress transport (SST) k-ω model and verified by experiments show that the full hub impeller exhibited superior hydraulic performance, with an efficiency about 1%–2% higher than the half hub impeller under all operating conditions. Entropy production theory is employed to analyze energy losses, we found that full hub impellers, compared to half hub models, significantly reduce energy loss, with a maximum reduction of about 5.45%. In addition, the full hub impeller reduces turbulence losses up to 5.32% on the one hand and increases friction losses up to 4.52% on the other hand, but turbulence losses account for a larger proportion of the total losses, so the overall efficiency is improved.
Improved photoresponse performance of self-powered solar-blind UV photodetectors based on n-Si/n-Ga2O3/p-Li:NiO dual-junction
Authors: Zhang Xian , Yue Zhiang , Zhao Enqin , Wei Shuaikang , Jiao Chenfei , Xin Meibo , Wang Kaiyuan , Zhai Ruofan , Ye Wenxuan , Wang Hui , Zhao Yang
Published: December 2024

The solar-blind photodetectors (SBPDs) based on the wide-bandgap semiconductor gallium oxide (Ga2O3) exhibit significant potential for applications in military, civilian, and medical fields. Although multiple structural designs of Ga2O3-based SBPDs have been proposed, their performance typically falls short of commercial standards. However, the photoresponse speed of most self-powered PDs decreases rapidly in the solar-blind region. To address this issue, we first prepared high-quality single-crystal β-Ga2O3 films using RF magnetron sputtering, which exhibit an average transmittance exceeding 85% across the 400–800 nm range and possess a relatively smooth surface. Subsequently, a superior performance self-powered SBPD of vertical structure of n-Si/n-Ga2O3/p-Li:NiO dual-junction was fabricated, which possesses a responsivity of 0.18 mA/W, a photo-to-dark current ratio of 395, rapid rise/decay times of 132/148 ms, and a specific detectivity of 1.57 × 109 Jones at 0 V bias under 254 nm illumination. The photocurrent of the device fully recovered to its initial level after experiencing changes in ambient temperature [from room temperature (RT) to 100 °C and back to RT], demonstrating robust stability in harsh environments. In addition, the valence band structures of p-Li:NiO and n-Ga2O3 were investigated in detail using XPS, and the working mechanism of the devices was analyzed based on the Fermi level alignment. The excellent performance of PDs can be attributed to the increased depletion layer width, which generates more photogenerated carriers. Additionally, the separation and transmission of photo-induced carriers are enhanced by the superposition of a double built-in electric field. Our strategy offers a promising approach for achieving high-performance Ga2O3-based photovoltaic PDs.
Modeling the relative permeability of gas and water flow in rock fractures with surface morphology parameters
Authors: He Xingji , Zhang Zhenyu , Wang Yakun , Liu Xiaoqian , Hao Shengpeng
Published: December 2024

Rock fracture morphology influences two-phase fluid flow in rock fractures. However, the role of the surface morphology of rock fractures in two-phase flow remains to be fully quantified. In this study, an analytical model for gas and water relative permeability in rough rock fractures was developed, incorporating surface roughness factor, hydraulic tortuosity, and surface tortuosity to quantify fracture morphology. The performance of the proposed model was evaluated through a comparison with empirical permeability models and experimental data. The proposed model accurately characterized two-phase fluid flow in rough fractures and examined the impact of surface morphology and flow dynamics on the relative permeability of two-phase fluids in rock fractures, demonstrating that increased surface roughness shifts the equal-permeability point toward higher water saturation and lower relative permeability. To investigate the influence of the flow dynamics on relative permeability, the proposed model was extended to express the Reynolds number of two-phase fluids as a function of water saturation and relative permeability, enabling a detailed exploration of the evolution law of relative permeability with Reynolds number.
Continuous modulation of monolayer MoS2 optical signals using a wedge-like substrate
Authors: Miao Gesong , Xu Xiangrui , Huang Junjie , Lin Gaoxiang , Xu Yanting , Huang Chenyi , Zhou Yinghui , Zhang Yufeng , Cai Weiwei , Zhang Xueao
Published: December 2024

Raman and PL (photoluminescence) spectroscopy are effective techniques for characterizing the physical properties of transition metal dichalcogenides (TMDCs). Modulating intensities of these optical signals is crucial for the advancement of research and the subsequent application of TMDCs. However, it is challenging to continuously modulate optical signals' intensities. Herein, by using a wedge-like SiO2/Si substrate, the intensities of optical signals of monolayer MoS2 are enhanced continuously, which results in ~22 times and ~39 times gain in E2g1 and A1g Raman mode, respectively, and a ~13 times gain in the PL intensity. The results are of significant importance for monolayer TMDCs' characterization and applications, e.g., optoelectronics.
Self-organizing network representation of human heart
Authors: Liu Runsang , Yang Hui
Published: December 2024

Network represents adjacent relationships, connections, and interactions among constituent elements in complex systems but often loses critical information about spatial configurations. However, structure–function relationships in biological systems, e.g., the human heart, are highly dependent on both connectivity relationships and geometric details. Therefore, this paper presents a new self-organizing approach to derive the geometric structure from a network representation of the heart. We propose to simulate the network as a physical system, where nodes are treated as charged particles and edges as springs and then let these nodes self-organize to reconstruct geometric details. Despite random initiations, this network evolves into a steady topology when its energy is minimized. This study addresses the open question, i.e., “whether a network representation can effectively resemble spatial geometry of a biological system,” thereby paving a stepstone to leverage network theory to investigate disease-altered biological functions.
Correlation characteristics of oscillation dynamic and acoustic behavior of a sonoluminescence cavitation bubble
Authors: Jiang Zhentao , Wu Wenwei , Meng Zifei , Ren Zhipeng , Chu Weimeng
Published: December 2024

The acoustic cavitation oscillation behavior of a single bubble and the resulting characteristic pressure evolution is a complex dynamic phenomenon. The coupling mechanisms among many characteristic pressures that affect the oscillation characteristics are still ambiguous. A correlation method is applied to analyze the degree of correlation between characteristic pressures and bubble oscillations. The effects of ambient pressure, bubble state, and propagation of driving acoustic pressure on bubble oscillation and size were investigated. The results indicate that the viscosity is the dominant factor affecting bubble oscillating velocity during the growth or collapse processes. The surface tension is strongly correlated with the bubble oscillation, and the oscillating velocity of a bubble greatly suppresses the effect of the viscosity on the bubble oscillation. In particular, the sinusoidal variation in driving acoustic pressure strongly correlates with bubble radius oscillation, and its correlation with bubble acceleration increases linearly. Moreover, two linear relationships between the ambient pressure and the frequency to the characteristic radius are obtained.
Density-based long-range electrostatic descriptors for machine learning force fields
Authors: Faller Carolin , Kaltak Merzuk , Kresse Georg
Published: December 2024

This study presents a long-range descriptor for machine learning force fields that maintains translational and rotational symmetry, similar to short-range descriptors while being able to incorporate long-range electrostatic interactions. The proposed descriptor is based on an atomic density representation and is structurally similar to classical short-range atom-centered descriptors, making it straightforward to integrate into machine learning schemes. The effectiveness of our model is demonstrated through comparative analysis with the long-distance equivariant (LODE) [Grisafi and Ceriotti, J. Chem. Phys. 151, 204105 (2019)] descriptor. In a toy model with purely electrostatic interactions, our model achieves errors below 0.1%, worse than LODE but still very good. For real materials, we perform tests for liquid NaCl, rock salt NaCl, and solid zirconia. For NaCl, the present descriptors improve on short-range density descriptors, reducing errors by a factor of two to three and coming close to message-passing networks. However, for solid zirconia, no improvements are observed with the present approach, while message-passing networks reduce the error by almost a factor of two to three. Possible shortcomings of the present model are briefly discussed.
Association between adequate protein intake and quadriceps quantity and quality during rehabilitation in people with subacute stroke
Authors: Tanaka Shu , Suzuki Mizue , Kimura Yosuke , Koyama Shingo , Masuda Hiroaki , Kojima Iwao , Suzukawa Katsumi , Takasugi Kenichiro , Yamada Minoru
Published: December 2024

Background We aimed to investigate the association between protein intake and quadriceps quantity and quality on the paretic and non-paretic sides during rehabilitation in people with subacute stroke. Method Eighty-six people with stroke were recruited from a rehabilitation ward. We measured quadriceps muscle quantity and quality on the paretic and non-paretic sides using ultrasonography at admission and after 4 weeks. Protein intake was assessed 2 or 3 weeks after admission, and participants were classified into two groups: adequate and inadequate protein intake groups. Analysis of covariance was used to determine the effects of protein intake on quadriceps muscle quantity and quality. Results The mean age (standard deviation), median interval between stroke onset and admission (interquartile range) and male proportion of the study participants were 67.6 (13.5) years, 22.5 (16.8–31.3) days, and 54.7%, respectively. The adequate protein intake group showed significantly greater improvements in paretic-side quadriceps thickness than the inadequate group (group-by-time interaction, F = 8.771, P = 0.004). In contrast, no significant interactions were observed in quadriceps thickness on the non-paretic side (F = 2.383, P = 0.127) and quadriceps echo intensity on both sides (paretic-side: F = 0.020, P = 0.887, non-paretic side: F = 0.181, P = 0.672). Conclusions Adequate protein intake may be useful for improving quadriceps quantity on the paretic side in people with subacute stroke undergoing rehabilitation. However, quadriceps quantity on the non-paretic side and quadriceps quality on both sides were not significantly associated with adequate protein intake.
Global adherence to a healthy and sustainable diet and potential reduction in premature death
Authors: Gu Xiao , Bui Linh P. , Wang Fenglei , Wang Dong D. , Springmann Marco , Willett Walter C.
Published: December 2024

The Planetary Health Diet (PHD), also known as the EAT-Lancet reference diet, was developed to optimize global dietary quality while keeping the environmental impacts of food production within sustainable planetary boundaries. We calculated current national and global adherence to the PHD using the Planetary Health Dietary Index (PHDI). In addition, we used data on diet and mortality from three large US cohorts (n = 206,404 men and women, 54,536 deaths) to estimate the total and cause-specific mortality among adults 20 y of age and older that could be prevented by shifting from current diets to the reference PHD. The PHDI varied substantially across countries, although adherence was universally far from optimal (mean PHDI = 85 out of 140). By improving the global PHDI to 120, approximately 15 million deaths (27% of total deaths) could be prevented annually. Estimates of preventable deaths due to this shift ranged from 2.5 million for cardiovascular diseases to 0.7 million for neurodegenerative diseases. Our analysis suggests that adopting healthy and sustainable diets would have major direct health benefits by reducing mortality due to multiple diseases and could contribute substantially to achieving the United Nations Sustainable Development Goals. These numbers of preventable deaths are based on evidence that human biology is similar across racial and ethnic groups, but the exact numerical estimates should be interpreted with caution because some assumptions used for the calculations build on limited data. Refinement of these estimates will be possible when additional regional data on diet and mortality become available.
Substitution patterns and price response for plant-based meat alternatives
Authors: Jahn Steffen , Guhl Daniel , Erhard Ainslee
Published: December 2024

Efforts to promote sustainable resource use through reduced meat consumption face challenges as global meat consumption persists. The resistance may be attributed to the lower sales price of meat compared to most plant-based meat alternatives (PBMAs). Addressing this, our research delves into the pivotal question of which PBMAs resonate most with consumers and how pricing affects demand. In a hypothetical restaurant context, we conducted 2 representative studies among 2,126 individuals in the United States to scrutinize preferences for meat, analog, semi-analog, and non-analog burgers. First, in a survey, we assessed rankings of the four burgers, alongside evaluating participants’ genuine consideration of these choices to discern a diverse preference distribution. Subsequently, in an experiment, we examined the influence of prices on participants’ consideration and choice of PBMAs, thereby capturing both phases of the decision-making process. Our survey shows that meat has considerably higher utility and consumer preference than all PBMAs on average, but we also find substantial heterogeneity (i.e., some consumers prefer PBMAs over meat). In the experiment, we establish that there is a negative association between the consideration of meat and PBMA burgers, though consideration of any one PBMA is positively associated with considering other PBMAs. A noteworthy increase in consideration and choice is observed when prices of PBMAs are reduced, while changing the price of the meat burger only has minimal effect on demand. Such findings underscore the importance of affordability beyond price parity in catalyzing the shift toward plant-based diets.
Liouville theory on a horizon: point particle/scalar field duality and Page-like curve
Authors: Roux J-B
Published: December 2024

We show that the consequences of a recent paper on quantum gravity are (1) a duality between point particles and massive scalar propagators, (2) the recovery of the entropy of a boundary (a black hole) in the same form as that of the EFT approach to quantum gravity and (3) a quantum correction to Hawking radiations and a Page-like curve. In this recent paper, information about what lies inside a boundary is encoded onto it, meaning that in this approach the information directly leaks from the horizon to the bulk in the form of Hawking radiations.
Recent advances in machine learning and deep learning-enabled studies on transition metal dichalcogenides
Authors: Bhawsar Shivani , Yang Eui-Hyeok
Published: December 2024

The machine learning and deep learning (ML/DL) techniques have significantly advanced the understanding and utilization of transition metal dichalcogenides (TMDs) by enabling efficient analysis, prediction, and optimization of their properties. ML/DL methods permit rapid screening, optimization and analysis of two-dimensional (2D) material candidates, potentially accelerating the discovery and development of TMDs with desired electronic, optoelectronic, and energy storage properties. This review provides a comprehensive review of ML/DL methods to enhance 2D materials research via the optimization of synthesis conditions, interpretation of complex data sets, and the use of generative adversarial networks and variational autoencoders for innovative material design and image processing tasks. Furthermore, it highlights the potential of ML/DL techniques in predicting and tailoring the electronic, optical, and mechanical properties of 2D materials to meet specific application requirements.
Study on the reproduction method of miniature Ga fixed points for shipborne thermometer calibration
Authors: Liu Junru , Wang Guangyao , Pan Jiang , Sun Jianping , Li Ting , Wei Chuanjie , Feng Weiwei , Sun Liquan , Wu Ziang , Niu Xingjun
Published: December 2024

The onsite calibration precision of the ocean thermometer can be efficiently raised by temperature scale transfer technology based on miniature fixed points. A new reproduction method of miniature Ga fixed points was studied for the sub-millikelvin precision measurement requirement. The onsite calibration system consists of a miniature Ga fixed point and a shipborne calibration device. The performance of miniature Ga fixed point is highly dependent on placement methods and the value-taking methods of phase transition temperature. This paper analyzed and compared the melting plateau of a miniature Ga fixed point with two placement methods and three value-taking methods of phase transition temperatures. The experimental results showed that utilizing horizontal placement and the average value method can achieve fixed point reproducibility within 1 mK. The performance of the miniature Ga fixed point was verified using the SBE 3plus thermometer from the SBE 911plus CTD system, with a thermometer accuracy of ±1 mK. The difference between the measured value by SBE 3plus and the Ga melting plateau value was within 0.5 mK. Thus, the study of the miniature Ga fixed point offers effective technical support for the onsite calibration of ocean thermometer.
Influence of radio-frequency magnetron sputtering power on electrical characteristics and positive bias stress stability of indium tin zinc oxide thin-film transistors
Authors: Chen Feilian , Wan Yunhao , Balasubramanian Paramasivam , Zhang Meng
Published: December 2024

As the pursuit of high-quality display panels intensifies, the importance of high-performance thin-film transistors (TFTs) becomes increasingly prominent. Indium tin zinc oxide (ITZO) TFTs, as one of the promising directions for high-performance metal oxide TFTs, impose high demands on their performance and reliability. In this study, the performance and stability of ITZO TFTs fabricated under different radio-frequency magnetron sputtering power conditions were systematically tested and investigated. After sputtering power optimization, the field effect mobility of ITZO TFTs reaches 29.68 cm2V–1.s, with a steep sub-threshold swing of 0.17 V/decade, near-zero threshold voltage, and good stability. Using atomic force microscopy and x-ray photoelectron spectroscopy characterization techniques, the thin films were analyzed to elucidate the relationship between sputtering power variations and oxygen vacancies.
Layered thermal effects dynamic characteristics modeling and application in piezoelectric stack actuator
Authors: Wu Xiao , Wang Xingjian , Wang Shaoping , Fan Siming
Published: December 2024

Piezoelectric actuators (PA) play an important role in high-frequency actuation scenarios in which their dynamic performance is directly affected by the heat generated by the action and its load changes. This study establishes a layered thermal dynamic model to describe the dynamic behavior of a PA applied to a designed high-frequency valve. First, a dynamic model of a single piezoelectric sheet was established using the generalized Hamilton’s principle, taking into account the thermal piezoelectric coupling effect. Second, a thermal dynamic model considering the boundary condition of the stakes was built by constructing a series quality elasticity model. Because the interaction between stacks affects the dynamic performance of the PA under high-frequency conditions, this study establishes a comprehensive dynamic model of the PA by integrating the piezoelectric layers and external loads. Finally, an experimental test rig is built to verify the effectiveness of the proposed model under real operating conditions. The results indicate that the proposed model more accurately describes the dynamic performance of the PA under high-frequency actuation and thermal change, and showcases the intricate connections between the various components within the actuator system.
A comparative analysis of relativistic particle pushers vis-à-vis computation time & accuracy
Authors: Yasir Mohammad , Saxena Vikrant
Published: December 2024

The performance of relativistic particle pushers has long been a topic of interest in the field of computational plasma physics, particularly from the point of view of the particle-in-cell approach. Previous works undertaken to compare such integrators have predominantly targeted the ultra-relativistic regime. In this paper, we utilize a custom-built code to study the core run-times of the Boris, the Vay, and the Higuera-Cary particle pushers for low-, high-, and ultra-relativistic particles. This is followed by a comparison of the three integrators in terms of accuracy and error. A fitness parameter is then proposed that can serve as a one-stop value to determine which method is more suitable for a particular simulation setup. It is hoped that through knowledge of such intricacies, the choice for the integrator will be easier to make depending on the problem at hand.