bluuebunny/crossref_metadata_2025 huggingface dataset:
Artificial neural-network-based subgrid-scale model for large-eddy simulation of isotropic turbulence
Authors: Yang Lei , Li Dong , Zhang Kai , Luo Kun , Fan Jianren
Published: July 2024

This study is concerned with accurately predicting the subgrid-scale (SGS) stress using an artificial neural network (ANN) with a linear eddy-viscosity term and a nonlinear term as the input variables. A priori and a posteriori tests are conducted to examine the prediction performance of the ANN-based SGS stress model in decaying homogeneous isotropic turbulence. In a priori test, the present ANN-based SGS model shows high correlation coefficients between the true and predicted SGS stresses, and excellent predictions of the SGS stress and dissipation. In a posteriori test, it is found that the ANN-based SGS model can predict the turbulence statistics more accurately than the traditional dynamic SGS models. The generalization capabilities of the model to untrained flow conditions and unstrained types of turbulent flow have been evaluated. It is found that the proposed ANN-based model can provide an accurate prediction of the SGS stress under different Reynolds numbers and flow types. A comparison among several existing ANN-based models with different input variables is presented, demonstrating a significant advantage of the present model.
Stability of plane Couette flow under anisotropic superhydrophobic effects
Authors: Zhang Liheng , Zhai Xueyan , Song Baofang , Wang Yaohong
Published: July 2024

We study the linear stability of plane Couette flow subject to an anisotropic slip boundary condition that models the slip effect of parallel microgrooves with a misalignment about the direction of the wall motion. This boundary condition has been reported to be able to destabilize channel flow far below the critical Reynolds number of the no-slip case. Unlike channel flow, the no-slip plane Couette flow is known to be linearly stable at arbitrary Reynolds numbers. Nevertheless, the results show that the slip can cause linear instability at finite Reynolds numbers also. The misalignment angle of the microgrooves that maximizes the destabilizing effect is nearly π/4, and the unstable modes are of small streamwise wavenumbers and relatively large spanwise wavenumbers. The flow is always more destabilized by two slippery walls compared to a single slippery wall. These observations are in qualitative agreement with the slippery channel flow with the same boundary condition, indicating that such an anisotropic superhydrophobic effect has a rather general destabilizing effect in shear flows regardless of the profile of the base flow. The absence of the Tollmien–Schlichting instability allows us to reveal the inverse relationship between the critical Reynolds number and the slip length as well as the misalignment in the small-parameter regime. The results suggest that arbitrary nonvanishing slip length and misalignment, with arbitrarily weak anisotropy, may suffice to destabilize plane Couette flow.
Surface atomic bidirectional migration modulated electrocatalytic activity in Co2MnO4 nanoparticles
Authors: Qi Caiyun , Xia Baorui , Peng Xuebing , Jiang Xingdong , Gao Daqiang
Published: July 2024

Polymetallic cationic spinel-type oxides are increasingly being used as catalysts for oxygen reduction/oxygen evolution reactions (ORR/OER). Here, we have modified the anti-spinel Co2MnO4 using a quenching strategy (CMO-Q) and demonstrated that the bidirectional migration of Co and Mn cations at the tetrahedral/octahedral positions is the essential reason for enhancing the ORR/OER performance. Electrochemical test results show that CMO-Q is better than Co2MnO4, OER initial potential decreased by 100 mV, and ORR current density increased from 4.2 to 7.3 mA cm−2 at 1600 rpm, with more stable CMO-Q-based zinc–air battery performance. Meanwhile, density functional theory calculations confirm that the primary factor contributing to the reduction of distance from the d-band center of Co and Mn to the Fermi level is the conductivity enhancement. This study offers insight into regulating the surface atomic migration and catalytic performance of spinel without compromising its stable structure.
Prediction model of aircraft hinge moment: Compressed sensing based on proper orthogonal decomposition
Authors: Zhang Qiao , Zhao Xuan , Li Kai , Tang Xinwu , Wu Jifei , Zhang Weiwei
Published: July 2024

By hinge moment, we mean the aerodynamic torque exerted on the rudder shaft by the airflow passing through the aircraft control surface, with obtaining high-precision results often relying on wind tunnel tests. Due to the complex aerodynamic balance insulation and installation errors that must be considered in cryogenic wind tunnels, the main method for calculating hinge moments is to directly integrate surface pressure distribution information. However, it is usually difficult to arrange enough pressure taps, resulting in the accuracy failing to meet expectations. Combining the sparse wind tunnel test data and low-precision computational fluid dynamics results, this paper introduces the compressed sensing based on proper orthogonal decomposition (CS-POD) method and presents the sub-Ma model and the full-Ma model for predicting hinge moments. The number of sensors and sensor positions are determined based on the sparsity of the numerical simulations and basis functions. Then, the CS algorithm solves the basis coefficients. Finally, the hinge moments are obtained by integrating the reconstruction pressure distribution which is calculated by linearly combining the basis functions and basis coefficients. The result shows that the full-Ma model exhibits higher prediction accuracy with approximately five sensors under subsonic and transonic cases, reducing the relative error of the sub-Ma model by 2–10 times, even at high angles of attack. The mean reconstruction accuracy for the hinge moments is 97.6%, and for the normal forces, it is 94.3%. Therefore, adding relevant terms when the number of samples is small can effectively improve modeling accuracy.
Impact of pulse exposure on chimera state in ensemble of FitzHugh–Nagumo systems
Authors: Rybalova E. , Semenova N.
Published: July 2024

In this article, we consider the influence of a periodic sequence of Gaussian pulses on a chimera state in a ring of coupled FitzHugh–Nagumo systems. We found that on the way to complete spatial synchronization, one can observe a number of variations of chimera states that are not typical for the parameter range under consideration. For example, the following modes were found: breathing chimera, chimera with intermittency in the incoherent part, traveling chimera with strong intermittency, and others. For comparison, here we also consider the impact of a harmonic influence on the same chimera, and to preserve the generality of the conclusions, we compare the regimes caused by both a purely positive harmonic influence and a positive–negative one.
A terahertz solid-state source interferometer–polarimeter designed for long pulse discharges on EAST
Authors: Wang S. X. , Liu H. Q. , Zhang J. B. , Xu C. , Lian H. , Zou Z. Y.
Published: July 2024

A 0.65 THz Solid-state Source Interferometer–Polarimeter (SSIP) with vertical viewing has been installed for line-integrated density and Faraday rotation measurements on Experimental Advanced Superconducting Tokamak (EAST). The SSIP utilizes three independent solid-state diode sources based on frequency multiplier (X48) to provide the probing beam at a fixed frequency of 0.65 THz with ∼2.5 mW output power, which provide an Intermediate Frequency (IF) with wide range, and the highest IF is up to ∼10 MHz. The mixers optimized for high sensitivity, ∼750 mV/mW, are used in the SSIP system, which permits multichannel interferometer–polarimeter on EAST with a low phase noise. The resolution of the integrated density is 3.3 × 1017 m−2, and the Faraday rotation is about 1.5°. The density measurement has been implemented with IF ∼0.85 MHz, in a plasma with plasma current ∼300 kA on EAST. The line-averaged density, 3.5 × 1019 m−3, measured by the SSIP shows good agreement with the results measured by the POlarimeter–INTerferometer (POINT) system and the CO2 dispersion interferometer system in the same discharge.
Spin orbit coupling enhanced thermionic cooling in two-dimensional semiconductor structures
Authors: Al-Mamun Abdullah , Zhang Chao
Published: July 2024

We theoretically investigate the effect of Rashba spin–orbit coupling (RSO) on thermionics properties of two-dimensional semiconductor. Due to the hybridization of parabolic and linear energy dispersion, the thermal energy equipartition is modified. The thermionic emission from the lower spin branch is enhanced and that from the upper spin branch is reduced. For a double quantum well cooling structure under lower doping, the net heat transported through the structure is enhanced by RSO. The coefficient of performance (COP) is improved by about 20% in the low bias regime and around 3% in the high bias regime. Since the RSO can be further tuned by an applied field, the COP can be further optimized.
Improvement of volatile switching in scaled silicon nanofin memristor for high performance and efficient reservoir computing
Authors: Ju Dongyeol , Lee Jungwoo , Kim Sungjun , Cho Seongjae
Published: July 2024

Conductive-bridge random access memory can be used as a physical reservoir for temporal learning in reservoir computing owing to its volatile nature. Herein, a scaled Cu/HfOx/n+-Si memristor was fabricated and characterized for reservoir computing. The scaled, silicon nanofin bottom electrode formation is verified by scanning electron and transmission electron microscopy. The scaled device shows better cycle-to-cycle switching variability characteristics compared with those of large-sized cells. In addition, synaptic characteristics such as conductance changes due to pulses, paired-pulse facilitation, and excitatory postsynaptic currents are confirmed in the scaled memristor. High-pattern accuracy is demonstrated by deep neural networks applied in neuromorphic systems in conjunction with the use of the Modified National Institute of Standards and Technology database. Furthermore, a reservoir computing system is introduced with six different states attained by adjusting the amplitude of the input pulse. Finally, high-performance and efficient volatile reservoir computing in the scaled device is demonstrated by conductance control and system-level reservoir computing simulations.
Influence of inhomogeneous temperature and field distribution on sound generation and its effect on reflectivity of a thin film heated by a femtosecond pulse
Authors: Danilov E. A. , Uryupin S. A.
Published: July 2024

One of the main methods for obtaining information about the generation of sound pulses in metals is to measure the reflection coefficient of a probe wave. Various theoretical models are used to interpret the results of measuring the contribution to reflection coefficient ΔR(t) due to sound-generated displacements of lattice atoms. The purpose of this paper is to establish the degree of accuracy of models used in the case of sound generation in thin films exposed to a femtosecond pulse. It is shown below that the assumption of uniform heating used for thin films is justified if the film thickness is less than the film heating depth and for thicker films at times greater than the film heating time over the entire thickness. For optically thick films, a relatively simple expression for the field can be used. If the film thickness is less than the skin layer depth of the pump field, then it is necessary to consider the field reflection from a substrate. In this case, depending on the optical properties of the metal and the substrate, taking into account reflection can lead to either an increase or a decrease in ΔR(t). It has been established that if the skin layer at the frequency of probe radiation is less than the film heating depth, then taking into account temperature gradients in the equation for the displacement of lattice atoms leads to small changes in ΔR(t). This makes it possible to significantly simplify calculations of the displacement of lattice atoms.
Hydrogen–iodine scattering. II. Rovibronic analysis and collisional dynamics
Authors: Weike Nicole , Eisfeld Wolfgang , Dunseath Kevin M. , Viel Alexandra
Published: July 2024

Our recently published [Weike et al., J. Chem. Phys. 159, 244119 (2023)] spin–orbit coupled diabatic potential energy model for HI is used in a thorough analysis of bound and quasi-bound states as well as elastic and inelastic processes in H + I collisions. The potential energy model, designed explicitly for studying scattering, accurately describes the various couplings in the system, which lead to complex dynamics. Ro-vibronic bound and quasi-bound states related to the adiabatic electronic ground state and an excited electronic state are analyzed. Calculations using the full 104 × 104 diabatic matrix model or a single adiabatic state are compared in order to investigate approximations in the latter. Elastic and inelastic scattering cross sections as well as thermal rates between the ground and first excited fine structure levels of iodine are computed for collision energies up to 12 500 cm−1. Resonances related to the quasi-bound states are analyzed in terms of their energy, width, lifetime, and decay probabilities. The effect of different resonances on the thermal rates is discussed. Resonances between 30 000 and 40 000 cm−1 are also studied for selected values of the total angular momentum, in particular their decay probabilities into different final states of iodine and hence their potential effect on branching ratios in photodissociation of HI.
A comment on the use of visually assessed fuel hazard ratings and scores for Australian fire management and research
Authors: Cruz Miguel G.
Published: July 2024

Background Assessment of fuel hazard has become the dominant method of describing Australian forest fuel complexes, despite a lack of evidence supporting the veracity of its underpinning assumptions. Aims To analyse and discuss the merits of fuel hazard ratings and scores in representing measurable fuel characteristics, such as fuel load and fire behaviour potential. Methods Published findings were reviewed, and available data analysed to investigate the validity of the Australian fuel hazard assessment concepts. Key results Multiple published studies showed the Australian fuel hazard assessment methods to be subjective and non-replicable. All available evidence shows no relationship between fuel hazard ratings and fuel quantity. No relationship between the ratings and fire behaviour potential was found. Conclusions The principles underpinning the use of fuel hazard ratings for fuel assessment were shown to be unfounded. The ratings cannot be converted into physical fuel characteristics or fire behaviour potential, and its application in Australian fire management is unwarranted.
Nanoparticle-assisted tubulin assembly is environment dependent
Authors: Unnikrishnan Mahima , Wang Yuhan , Gruebele Martin , Murphy Catherine J.
Published: July 2024

Nanomaterials acquire a biomolecular corona upon introduction to biological media, leading to biological transformations such as changes in protein function, unmasking of epitopes, and protein fibrilization. Ex vivo studies to investigate the effect of nanoparticles on protein–protein interactions are typically performed in buffer and are rarely measured quantitatively in live cells. Here, we measure the differential effect of silica nanoparticles on protein association in vitro vs. in mammalian cells. BtubA and BtubB are a pair of bacterial tubulin proteins identified in
Prosthecobacter
strains that self-assemble like eukaryotic tubulin, first into dimers and then into microtubules in vitro or in vivo. Förster resonance energy transfer labeling of each of the Btub monomers with a donor (mEGFP) and acceptor (mRuby3) fluorescent protein provides a quantitative tool to measure their binding interactions in the presence of unfunctionalized silica nanoparticles in buffer and in cells using fluorescence spectroscopy and microscopy. We show that silica nanoparticles enhance BtubAB dimerization in buffer due to protein corona formation. However, these nanoparticles have little effect on bacterial tubulin self-assembly in the complex mammalian cellular environment. Thus, the effect of nanomaterials on protein–protein interactions may not be readily translated from the test tube to the cell in the absence of particle surface functionalization that can enable targeted protein–nanoparticle interactions to withstand competitive binding in the nanoparticle corona from other biomolecules.
臘羅彝語的度量短語
Authors: Bu Weimei , Liu Hongyong
Published: July 2024

抽象的

臘羅彝語包含兩類不同的度量短語：出現在謂語動詞前的光桿度量短語以及出現在「度量短語+dɛ⁵⁵+名詞」結構中的度量短語。光杆度量短語語義上指向句中充當論元的光桿名詞，但句法上須先與謂語動詞組合，此類分裂式度量短語只具有單調性解讀。「度量短語+dɛ⁵⁵+名詞」結構具有歧義，既允許單調性解讀，也允許非單調性解讀，這兩種不同的語義解讀分別對應兩種不同的句法結構：準切分結構和定中結構。臘羅彝語度量短語的句法分佈進一步驗證了度量短語的單調性假設，具有重要的語言類型學價值。
An accelerated inexact Newton regularization scheme with a learned feature-selection rule for non-linear inverse problems
Authors: Long Haie , Zhang Ye , Gao Guangyu
Published: July 2024

With computational inverse problems, it is desirable to develop an efficient inversion algorithm to find a solution from measurement data through a mathematical model connecting the unknown solution and measurable quantity based on the first principles. However, most of mathematical models represent only a few aspects of the physical quantity of interest, and some of them are even incomplete in the sense that one measurement corresponds to many solutions satisfying the forward model. In this paper, in light of the recently developed iNETT method in (2023 Inverse Problems
39 055002), we propose a novel iterative regularization method for efficiently solving non-linear ill-posed inverse problems with potentially non-injective forward mappings and (locally) non-stable inversion mappings. Our approach integrates the inexact Newton iteration, the non-stationary iterated Tikhonov regularization, the two-point gradient acceleration method, and the structure-free feature-selection rule. The main difficulty in the regularization technique is how to design an appropriate regularization penalty, capturing the key feature of the unknown solution. To overcome this difficulty, we replace the traditional regularization penalty with a deep neural network, which is structure-free and can identify the correct solution in a huge null space. A comprehensive convergence analysis of the proposed algorithm is performed under standard assumptions of regularization theory. Numerical experiments with comparisons with other state-of-the-art methods for two model problems are presented to show the efficiency of the proposed approach.
Fabrication of microneedles using wire electric discharge machining and improving surface quality by electrochemical polishing
Authors: Sarkar Partha , Sidpara Ajay M
Published: July 2024

Microneedle (MN) arrays have many applications in biomedical engineering to deliver drugs transdermally or extract biomarkers from the interstitial fluid from the human skin. Several methods have been developed to fabricate different sizes and shapes of MN using polymers, ceramics and metals. However, most of these methods require expensive sophisticated machines and clean room facilities. So, it is difficult to fabricate microneedle arrays in large quantities at a reasonable cost. This study reports the fabrication of a high-quality stainless steel master pattern for an MN array using a wire-cut electric discharge machining process followed by electrochemical polishing (ECP). Different densities of a 5 × 5 array of microneedles with pyramidal shapes were fabricated by machining channels onto the workpiece surface in a criss-cross pattern. A systematic experimental study was carried out with reference to the offset between the two consecutive channel faces and the depth of channels. The output parameters are MN height (MNH), MN base (MNBW) and tip width (MNTW). The average needle tip width, base width, and height of microneedles were found to be 55.3 ± 5 µm, 679.8 ± 10 µm, and 914.7 ± 19 µm. Finally, the sharpness of the MN tips and the overall surface finish of the MN array were improved with ECP. The reductions in MNH, MNBW, and MNTW were reported to be −18.3%, −9.7%, and −95.4%, respectively, with a final tip width of 2.55 ± 1.62 µm. The MNs’ tip angle was reported to be 32.52° ± 1.56.
Exploring the origin of stronger survival of polarized vortex beams through scattering media
Authors: Paranjape Atharva , Guchhait Shyamal , B S Athira , Ghosh Nirmalya
Published: July 2024

Laguerre–Gaussian (LG) beams carrying orbital angular momentum (OAM) have shown promise in deep tissue imaging, medical diagnostics, and optical communication due to their robust propagation properties through scattering media. The insight on the mechanism for stronger survival of OAM carrying beam in tissue-like turbid media is expected to contribute towards a better understanding of light transport in the presence of scattering, as well as guide optimization of the intensity, phase, and polarization structure of light for use in biomedical applications like in tissue imaging. We examine the scattering properties by studying the propagation of polarized vortex beams transmitted through tissue-like turbid scattering media. We demonstrate that the intensity profile has a much more profound effect on depolarization than the phase profile for LG beams. Our results indicate that the observed stronger propagation for the higher-order LG beams is due to a higher anisotropy factor g, as seen by the incident beam. We have performed the degree of polarization measurements for the forward scattered light in the case of both LG beams and perfect vortex beams with varying topological charges. A comparison between the observed depolarization trends for the two classes of OAM-carrying beams suggests that the robust scattering properties of the LG beams originate from the intensity profile while the phase profile does not seem to play a major role in the stronger survival of OAM-carrying beam in turbid media.
Harnessing BN co-doping for superior thermal transport in phagraphene monolayer
Authors: Asfakujjaman  , Ghosh Mainak , Chowdhury Suman , Jana Debnarayan
Published: July 2024

In this study, we thoroughly explored the thermal transport and thermoelectric properties of BN-co-doped phagraphene structures in the context of first-principles computations combined with machine learning interatomic potential (MLIP) techniques. Our results demonstrate that doping positions can critically tune the thermal properties, offering potential advantages for both thermoelectric and heat transfer applications. Notably, enhanced thermal conductivity has been obtained for phagraphene with 10

%

co-doping. Additionally, the rectangular structural symmetry of phagraphene plays an important role for targeted thermal transport. Further, we observe negative Grüneisen parameter in these structures, suggesting negative thermal expansion. This will serves as an unique mechanism for controlling the thermal conductivity at different frequencies. Interestingly, n-type behavior of the structures is indicative of its negative Seebeck coefficient within the temperature range of 300–900 K. Moreover, these structures display significantly larger electrical conductivity compared to other two-dimensional (2D) materials. Apart from that, the calculated figure of merit of the structures under a constant relaxation time at 300 K shows considerably better response for some specific doped structures. We believe this study will play an important role in understanding the importance of structural modifications in tailoring the thermal properties of carbon-based 2D systems.
Novel ground state structures of N-doped LuH3
Authors: Verma Ashok K , Mishra Ajay K , Modak P
Published: July 2024

Ab-initio crystal structure searches have played a pivotal role in recent discoveries of high-Tc hydride superconductors under high pressure. Using evolutionary crystal searches, we predict novel ground state structures of N-doped LuH3 at ambient conditions. We find an insulating ground state structure for LuN0.125H2.875 (∼1.0 wt.% N), contrary to earlier studies where assumed structures were all metallic. This insulating behavior of ground state was found to persist up to ∼45 GPa. However our crystal structure searches revealed a metallic state for an H-deficient variant of LuN0.125H2.875. We study bonding characteristics of important structures by calculating electronic density of states, electronic-localization functions and Bader charges. Our Bader charge analysis shows that insulators have both H+ and H− ions whereas metals have only H− ions. We find that H+ ions are bonded to N atoms via a very short covalent bond. Thus we identify a clear relationship between formation of N–H bonds and insulating behavior of materials. Besides this, we perform crystal structure searches for three more compositions with higher N-content (>1.0 wt.%). Analysis of electronic properties shows that the ground states of these compositions are insulator.
High dynamic range structured illumination microscopy based on per-pixel coding
Authors: Qu Tong , Chai Changchun , Guo Jiahui , Wang Shuai , Ye Zhuohang , Li Zehao , Liu Xiaojun
Published: July 2024

Structured illumination microscopy (SIM) can achieve optical sectioning with high resolution, and have aroused extensive research interest. In SIM, a set of high-contrast illumination patterns are projected onto the sample to modulate the surface height information, and then, a decoding algorithm is applied to the modulated pattern images for high-quality optical sectioning. Applied to samples with large dynamic range of reflectivity, however, SIM may fail to achieve high quality sectioning for accurate surface reconstruction. Herein, an active digital micromirror device (DMD) based illumination method using per-pixel coded strategy is proposed in SIM to realize high-quality measurement for surface with complex reflection characteristics. In this method, the mapping relationship between DMD and the camera is established pixels by pixels, which enables the illumination intensity on the sample surface can be flexibly modulated by DMD pixel-level modulation corresponding to reflectivity distribution of the surface, and allows the camera pixels always to have reasonable exposure intensity for high precision measurement. More importantly, we put forward an adaptive light intensity control algorithm to improves the signal-to-noise ratio of acquired images without compromising modulation depth of pattern and measurement efficiency. Extensive comparative experiments were conducted and demonstrated that the proposed method can retrieve the surface morphology information of micro-scale complex reflectivity surfaces with high accuracy.
Signal enhancement method for gearboxes fault diagnosis in robotic flexible joint
Authors: Li Jianlong , Liu Xiaoqin , Wu Xing , Wang Dongxiao , Xu Kai , Lin Sheng
Published: July 2024

Motor current signal analysis (MCSA) provides a non-intrusive approach to fault diagnosis. However, the fault impact reacting in the current is reduced due to the presence of flexible structures in the transmission path from the fault source to the motor. Therefore, this paper proposes a method to enhance the frequency domain of the current signal of a single mechanical fault through a transfer model between motor torque and link vibration. First, the joint system dynamics model was developed based on a three-inertia simplified model. The transfer model of motor torque and link vibration was defined based on the system dynamics. The link vibration is then estimated based on the transfer model and electromagnetic torque. Link vibration signal is considered as an enhancement of the torque signal. Finally, the link vibration signature analysis is performed instead of MCSA. The experimental results show that the method is effective in enhancing the features of individual mechanical faults and improving the fault diagnosis performance.
A novel deformation measurement method for rotating blade based on PSO-ILS image correlation matching and mismatch correction
Authors: Wu Huilin , Sun Chuanzhi , Liu Yongmeng , Zou Limin , Tan Jiubin
Published: July 2024

Aiming at the problem of small measurement range and difficult measurement of traditional contact sensor method in the rotating state of aero-engine blades, this paper proposes a novel deformation measurement method for rotating blade based on image correlation matching and mismatch correction. Firstly, a Particle Swarm Optimization-Iterative Local Search image intelligent matching algorithm is proposed, which effectively balances global search and local optimization, and the image matching displacement accuracy reaches 10−3 pixel. Secondly, a mismatch point detection method based on multi-scale local Root Mean Square is proposed, and the high-precision detection of mismatch points is realized by considering the influence of local structure. Finally, through the hierarchical refinement of the sub-pixel level mismatch point correction method, the mismatch point is corrected in the two iterative stages of global search and local optimization. The corrected mismatch point response value K is reduced by 99% compared with that before correction, which further improves the accuracy of deformation field calculation. In the experiment, the deformation of the rotating blade of 4500 RPM is measured, which proves that the image intelligent matching algorithm and the deformation field calculation method proposed in this paper can provide new methods and technical support for the accurate measurement of the blade surface deformation.
Half-wave voltage controllable optical voltage sensor with arbitrary electric field direction modulation*
Authors: Lin Yifan , Xu Qifeng , Li Jun , Xie Nan , Yang Yang
Published: July 2024

An optical voltage sensor with an arbitrary electric field direction modulation (AEFDM) mode is proposed to increase the half-wave voltage. The mode is realized by heterogeneous electrodes arranged in a center-symmetric way, and generates an electric field with a direction at an arbitrary angle to the light propagation direction. The finite element method and coupling wave theory are used to design and optimize the electrodes and field distribution. The experimental results show that heterogeneous electrodes and AEFDM mode are able to regulate the sensor’s half-wave voltage in a range from 1 to 30 times (47–1409 kV), with 0.5 class accuracy and 99.99% linearity. This novel AEFDM method proposes a new electrode shape and position, reducing temperature drift to 50% compared to solid-state voltage divider method.
SNW YOLOv8: improving the YOLOv8 network for real-time monitoring of lump coal
Authors: Wu Ligang , Chen Le , Li Jialong , Shi Jianhua , Wan Jiafu
Published: July 2024

Due to its large size of coal and high mining output, lump coal is one of the hidden risks in mining conveyor damage. Typically, lump coal can cause jamming and even damage to the conveyor belt during the coal mining and transportation process. This study proposes a novel real-time detection method for lump coal on a conveyor belt. The space-to-depth Conv (SPD-Conv) module is introduced into the feature extraction network to extract the features of the mine’s low-resolution lump coal. To enhance the feature extraction capability of the model, the normalization-based attention module (NAM) is combined to adjust weight sparsity. After loss function optimization using the Wise-IoU v3 (WIoU v3) module, the SPD-Conv-NAM-WIoU v3 YOLOv8 (SNW YOLO v8) model is proposed. The experimental results show that the SNW YOLOv8 model outperforms the widely used model (YOLOv8) in terms of precision and recall by 15.82% and 11.71%, respectively. Significantly, the real-time detection speed of the SNW YOLOv8 model is increased to 192.93 f s−1. Compared to normal models, the SNW YOLO v8 model overcomes the disadvantages of normal models, such as being overweight, and the parameters of SNW YOLO v8 are reduced to only 6.04 million with a small model volume of 12.3 MB. Meanwhile, the floating point of SNW YOLOv8 is significantly reduced. Consequently, it demonstrates excellent lump coal detection performance, which may open up a new window for coal mining optimization.
Multi-graph attention fusion graph neural network for remaining useful life prediction of rolling bearings
Authors: Xiao Yongchang , Cui Lingli , Liu Dongdong
Published: July 2024

Graph neural network (GNN) has the proven ability to learn feature representations from graph data, and has been utilized for the tasks of predicting the machinery remaining useful life (RUL). However, existing methods only focus on a single graph structure and cannot integrate the correlation information contained in multi-graph structures. To address these issues, a multi-graph structure GNN prediction method with attention fusion (MGAFGNN) is proposed in this paper for GNN-based bearing RUL prediction. Specifically, a multi-channel graph attention module is designed to effectively learn the similar features of node neighbors from different graph data and capture the multi-scale latent features of nodes through the nonlinear transformation. Furthermore, a multi-graph attention fusion module (MGAFM) is proposed to extract the collaborative features from the interaction graph, thereby fusing the feature embeddings from different graph structures. The fused feature representation is sent to the long short-term memory network to further learn the temporal features and achieve RUL prediction. The experimental results on two bearing datasets demonstrate that MGAFGNN outperforms existing methods in terms of prediction performance by effectively incorporating multi-graph structural information.
Polycrystalline silicon, a molecular dynamics study: II. Grains, grain boundaries and their structure
Authors: Lahti Antti , Santonen Mikael , Rad Zahra Jahanshah , Miettinen Mikko , Ebrahimzadeh Masoud , Lehtiö Juha-Pekka , Laukkanen Pekka , Punkkinen Marko , Paturi Petriina , Kokko Kalevi , Kuronen Antti , Li Wei , Vitos Levente , Parkkinen Katja , Eklund Markus
Published: July 2024

Polycrystalline silicon (poly-Si) is an excellent material for use in microelectronic devices, both in electrical and mechanical applications. Its mechanical and electrical properties are widely adjustable, its processing technology is compatible with existing microcircuit manufacturing technology, and its availability and recyclability are at a high level. Here, we focus on investigating the properties of poly-Si that distinguish it from other forms of silicon, that is, grains, grain boundaries, and the conditions and treatments that determine grain and grain boundary properties. Starting from the molecular dynamics simulations of the deposition of thin poly-Si films under different growth conditions we study the properties of the films, grains, and grain boundaries as a function of growth time, growth temperature, and post-annealing. We aim to get data and information that will form the essential basis for future research on the electrical properties of poly-Si. The main results are: (i) the effect of post-annealing on the distribution of the grain size and grain boundary thickness (ii) the distribution of the grain orientations, and (iii) the density of the 3- and 5-bonded atoms as a function of deposition temperature.
Cathodoluminescence studies of the optical properties of a zincblende InGaN/GaN single quantum well
Authors: Gundimeda Abhiram , Kusch Gunnar , Frentrup Martin , Kappers Menno J , Wallis David J , Oliver Rachel A
Published: July 2024

Zincblende GaN has the potential to improve the efficiency of green- and amber-emitting nitride light emitting diodes due to the absence of internal polarisation fields. However, high densities of stacking faults are found in current zincblende GaN structures. This study presents a cathodoluminescence spectroscopy investigation into the low-temperature optical behaviour of a zincblende GaN/InGaN single quantum well structure. In panchromatic cathodoluminescence maps, stacking faults are observed as dark stripes, and are associated with non-radiative recombination centres. Furthermore, power dependent studies were performed to address whether the zincblende single quantum well exhibited a reduction in emission efficiency at higher carrier densities—the phenomenon known as efficiency droop. The single quantum well structure was observed to exhibit droop, and regions with high densities of stacking faults were seen to exacerbate this phenomenon. Overall, this study suggests that achieving efficient emission from zinc-blende GaN/InGaN quantum wells will require reduction in the stacking fault density.
Strong doping reduction on wafer-scale CVD graphene devices via Al2O3 ALD encapsulation
Authors: Dockx K , Barnes M D , Wehenkel D J , van Rijn R , van der Zant H S J , Buscema M
Published: July 2024

We present the electrical characterization of wafer-scale graphene devices fabricated with an industrially-relevant, contact-first integration scheme combined with Al2O3 encapsulation via atomic layer deposition. All the devices show a statistically significant reduction in the Dirac point position,

V
cnp

, from around +47 V to between −5 and 5 V (on 285 nm SiO2), while maintaining the mobility values. The data and methods presented are relevant for further integration of graphene devices, specifically sensors, at the back-end-of-line of a standard CMOS flow.
Substrate-induced strain in molybdenum disulfide grown by aerosol-assisted chemical vapor deposition
Authors: Adams Lewis J , Matthews Peter D , Morbec Juliana M , Balakrishnan Nilanthy
Published: July 2024

Transition metal dichalcogenides have been extensively studied in recent years because of their fascinating optical, electrical, and catalytic properties. However, low-cost, scalable production remains a challenge. Aerosol-assisted chemical vapor deposition (AACVD) provides a new method for scalable thin film growth. In this study, we demonstrate the growth of molybdenum disulfide (MoS2) thin films using AACVD method. This method proves its suitability for low-temperature growth of MoS2 thin films on various substrates, such as glass, silicon dioxide, quartz, silicon, hexagonal boron nitride, and highly ordered pyrolytic graphite. The as-grown MoS2 shows evidence of substrate-induced strain. The type of strain and the morphology of the as-grown MoS2 highly depend on the growth substrate’s surface roughness, crystallinity, and chemical reactivity. Moreover, the as-grown MoS2 shows the presence of both direct and indirect band gaps, suitable for exploitation in future electronics and optoelectronics.
Constrained hidden Markov models reveal further Hsp90 protein states
Authors: Tancredi Riccardo , Feltrin Antonio , Infirri Giosuè Sardo , Toso Simone , Leonie Vollmar  , Hugel Thorsten , Baiesi Marco
Published: July 2024

Time series of conformational dynamics in proteins are usually evaluated with hidden Markov models (HMMs). This approach works well if the number of states and their connectivity is known. However, for the multi-domain protein Hsp90, a standard HMM analysis with optimization of the BIC (Bayesian information criterion) cannot explain long-lived states well. Therefore, here we employ constrained HMMs, which neglect transitions between states by including assumptions. Gradually tuning a model with justified and focused changes allows us to improve its effectiveness and the score of the BIC. This became possible by analyzing time traces with several thousand observable transitions and, therefore, superb statistics. In this scheme, we also monitor the residences in the states reconstructed by the model, aiming to find exponentially distributed dwell times. We show how introducing new states can achieve these statistics but also point out limitations, e.g. for substantial similarity of two states connected to a common neighbor. One of the states displays the lowest free energy and could be the idle open ‘waiting state’, in which Hsp90 waits for the binding of nucleotides, cochaperones, or clients.
On fractional discrete financial system: Bifurcation, chaos, and control
Authors: Diabi Louiza , Ouannas Adel , Hioual Amel , Momani Shaher , Abbes Abderrahmane
Published: July 2024

The dynamic analysis of financial systems is a developing field that combines mathematics and economics to understand and explain fluctuations in financial markets. This paper introduces a new three-dimensional (3D) fractional financial map and we dissect its nonlinear dynamics system under commensurate and incommensurate orders. As such, we evaluate when the equilibrium points are stable or unstable at various fractional orders. We use many numerical methods, phase plots in 2D and 3D projections, bifurcation diagrams and the maximum Lyapunov exponent. These techniques reveal that financial maps exhibit chaotic attractor behavior. This study is grounded on the Caputo-like discrete operator, which is specifically influenced by the variance of the commensurate and incommensurate orders. Furthermore, we confirm the presence and measure the complexity of chaos in financial maps by the 0–1 test and the approximate entropy algorithm. Additionally, we offer nonlinear-type controllers to stabilize the fractional financial map. The numerical results of this study are obtained using MATLAB.
Entropy variances of pure coherent states in the diffusion channel
Authors: Wu 吴 Wei-Feng 卫锋 , Fang 方 Yong 勇 , Fu 付 Peng 鹏
Published: July 2024

Using the operator correspondence of the real and fictious modes in the thermo entangled state representation, we solve the quantum master equation describing the diffusion channel and obtain the Kraus operator-sum representation of its analytical solution. we find that the pure coherent states evolve into the new mixed thermal superposed states in the diffusion channel. Also, we investigate the statistical properties of the initial coherent states and their entropy evolutions in the diffusion channel, and find that the entropy evolutions are only related to the decay time and without the amplitudes of the initial coherent states.
Quantum confinement of carriers in the type-I quantum wells structure
Authors: Li 李 Xinxin 欣欣 , Deng 邓 Zhen 震 , Jiang 江 Yang 洋 , Du 杜 Chunhua 春花 , Jia 贾 Haiqiang 海强 , Wang 王 Wenxin 文新 , Chen 陈 Hong 弘
Published: July 2024

Quantum confinement is recognized to be an inherent property in low-dimensional structures. Traditionally, it is believed that the carriers trapped within the well cannot escape due to the discrete energy levels. However, our previous research has revealed efficient carrier escape in low-dimensional structures, contradicting this conventional understanding. In this study, we review the energy band structure of quantum wells along the growth direction considering it as a superposition of the bulk material dispersion and quantization energy dispersion resulting from the quantum confinement across the whole Brillouin zone. By accounting for all wave vectors, we obtain a certain distribution of carrier energy at each quantized energy level, giving rise to the energy subbands. These results enable carriers to escape from the well under the influence of an electric field. Additionally, we have compiled a comprehensive summary of various energy band scenarios in quantum well structures relevant to carrier transport. Such a new interpretation holds significant value in deepening our comprehension of low-dimensional energy bands, discovering new physical phenomena, and designing novel devices with superior performance.
Comparative study of nudged elastic band and molecular dynamics methods for diffusion kinetics in solid-state electrolytes
Authors: Lin 林 Aming 啊鸣 , Shi 石 Jing 晶 , Wei 魏 Su-Huai 苏淮 , Sun 孙 Yi-Yang 宜阳
Published: July 2024

Considerable efforts are being made to transition current lithium-ion and sodium-ion batteries towards the use of solid-state electrolytes. Computational methods, specifically nudged elastic band (NEB) and molecular dynamics (MD) methods, provide powerful tools for the design of solid-state electrolytes. The MD method is usually the choice for studying the materials involving complex multiple diffusion paths or having disordered structures. However, it relies on simulations at temperatures much higher than working temperature. This paper studies the reliability of the MD method using the system of Na diffusion in MgO as a benchmark. We carefully study the convergence behavior of the MD method and demonstrate that total effective simulation time of 12 ns can converge the calculated diffusion barrier to about 0.01 eV. The calculated diffusion barrier is 0.31 eV from both methods. The diffusion coefficients at room temperature are 4.3 × 10−9 cm2⋅s−1 and 2.2 × 10−9 cm2⋅s−1, respectively, from the NEB and MD methods. Our results justify the reliability of the MD method, even though high temperature simulations have to be employed to overcome the limitation on simulation time.
Factors Influencing Tourist Visit to Jumog Waterfall Ngargoyoso Sub-District Karanganyar District
Authors: Kedaton E. , Kiat U. E. I.
Published: July 2024

The influence of accessibility, facilities, and tourist location on visitor satisfaction to Jumog Waterfall. There are three objectives in this study, namely: Analyzing the effect of accessibility on visitor satisfaction to Jumog Waterfall; Knowing the effect of facilities on visitor satisfaction with Jumog Waterfall; and Analyzing the effect of location on visitor satisfaction with Jumog Waterfall. The tool used in multiple linear regression analysis is SPSS 16.0. Accessibility, facilities, and location as independent variables. Visitor satisfaction is dependent. The test model for multiple linear regression analysis is the F-Test and T-Test, where the Coefficient Regression Full Model and Anova Model are selected as the best models. The first analysis indicates a significant positive impact of enhanced accessibility on visitor satisfaction at Jumog Waterfall, supported by a notable F-Test value of 2.70. The findings highlight a meaningful correlation between improved facilities and heightened visitor satisfaction at Jumog Waterfall, as evidenced by the obtained t-test distribution value of 1.984. The study identifies a substantial positive effect of favorable location characteristics on visitor satisfaction at Jumog Waterfall, further supported by the overall significance level of 0.000 < 0.05, leading to the rejection of the null hypothesis (H0).