bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluid–structure interaction on the rotor-dynamic characteristics of a low-specific-speed centrifugal pump considering multi-scale fluid excitation effects
Authors: Zhou Wenjie , Ma Ji , Ma Zhenlai , Yu Wanbo , Su Huihao , Gao Bo
Published: November 2024

Centrifugal pump rotor system is a complex vibration system due to the unsteady multi-scale fluid–solid interactions (FSIs). In order to explore the coupling vibration of the rotor system between the multi-scale fluid domain and different flow conditions, the bidirectional fluid–solid interaction (BFSI) was carried out, and the numerical and experimental results of the centrifugal pump performance were compared. The transient forces of the impeller and vibration characteristics of rotor system considering BFSI for different flow rates, wear-ring clearances, and axial movements were also studied in detail. The results show that the maximum errors of head and efficiency between the simulation and experiment are only 5.41% and 2.33%, respectively. The radial force of impeller is smallest at 1.0Qd and the axial force decreases with the increase in flow rate. The average deformation and stress of the rotor system reaches to 0.35 mm and 70.7 MPa, respectively, when the axial movement increases to +1.5 mm. The vibration acceleration on the blades increases gradually from the root to the top, and the vibration acceleration on the shaft is greater than that at the impeller.
Near-zero TCF 11.6-GHz lamb wave resonator based on 128°Y-cut LiNbO3
Authors: Huang Feixuan , Du Mingye , Ma Chen , He Xi , Suo Feiya , Li Jiawei , Wu Tao , Wang Nan
Published: November 2024

In this paper, a high-frequency lamb wave resonator (LWR) with near zero temperature coefficient of frequency (TCF) is designed, fabricated, and measured. The reported resonator is of a bi-layer structure consisting of lithium niobate (LiNbO3 or LN) and silicon dioxide (SiO2), and lithographically patterned aluminum (Al) inter-digitated electrode fingers on top of the bi-layer structure. By adjusting the thickness ratio of LN and SiO2 layers, both the electromechanical coupling (k2) and the TCF, including both TCF at resonant frequency (TCFr) and TCF at anti-resonant frequency (TCFa), of the thickness shear (TS) type LWR are optimized. Experimental results, which are in excellent agreement with theoretical analysis, show that the fabricated 11.6-GHz LWR achieves a k2 of 12.2%, with TCFr and TCFa being −4.2 and −5.4 ppm/K over a temperature range from 30 °C to 85 °C, respectively, demonstrating huge potential in applications for future wireless communication systems above 10 GHz.
Defect engineering-induced Seebeck coefficient and carrier concentration decoupling in CuI by noble gas ion implantation
Authors: Markwitz Martin , Murmu Peter P. , Mori Takao , Kennedy John V. , Ruck Ben J.
Published: November 2024

Copper(I) iodide, CuI, is the leading p-type nontoxic and earth-abundant semiconducting material for transparent electronics and thermoelectric generators. Defects play a crucial role in determining the carrier concentration, scattering process, and, therefore, the thermoelectric performance of a material. As a result of defect engineering, the power factor of thin film CuI was increased from 332±32 to 578±58 μW m−1K−2 after implantation with noble gas ions (Ne, Ar, or Xe). The increased power factor is due to a decoupling of the Seebeck coefficient and electrical conductivity identified through a changing scattering mechanism. Ion implantation causes the abundant production of Frenkel pairs, which were found to suppress compensating donors in CuI, and this scenario was also supported by density functional theory calculations. The compensating donor suppression led to a significantly improved Hall carrier concentration, increasing from 6.5×1019±0.1×1019 to 11.5×1019±0.4×1019 cm−3. This work provides an important step forward in the development of CuI as a transparent conducting material for electronics and thermoelectric generators by introducing beneficial point defects with ion implantation.
Investigation on flow–acoustic resonance behaviors inside ducts with tandem cavities using a high-order spectral/hp element method
Authors: Jia Sichang , Wang Peng , Liu Yingzheng
Published: November 2024

This study numerically investigates the flow–acoustic resonance behaviors inside ducts with tandem cavities, containing the flow-excited acoustic eigenmodes and elevated flow dynamics under self-sustained acoustic forcing. An advanced high-order spectral/hp element method integrated with implicit large-eddy simulations was utilized to solve the nonlinear compressible Navier–Stokes equations, which effectively identified the fully coupled self-sustained flow–acoustic resonance fields. The benchmark shallow cavity configuration with a length-to-depth (L/D) ratios of 2 was motivated by the experimental findings from Shaaban and Ziada [“Fully developed building unit cavity source for long multiple shallow cavity configurations,” Phys. Fluids 30, 086105 (2018)], in which the intensive flow–acoustic resonance was occurred at a Reynolds number of 1.3×105, and we further investigated three deeper cavity configurations with L/D of 1, 2/3, and 1/2 for numerical validation and further comparison. Subsequently, aeroacoustic characteristics were assessed by analyzing the wall pressure fluctuations, indicating broader resonance regions and augmented pressure pulsation amplitudes extending from main duct to local cavity volumes with larger cavity depths. As feedback, the intensified acoustic forcing can modulate the cavity flow dynamics into stronger fluctuation levels. Furthermore, the spectral proper orthogonal decomposition analysis was conducted on the pressure fields and velocity fields, respectively. The significant fluctuations in acoustic pressure were linked to transitional acoustic modes that were present as global modes in the main duct and local modes in tandem cavities. As for velocity analysis, coherent vortex structures were extracted along the cavity entrances. These vortex structures caused progressively amplified velocity fluctuations and classified the shear layers into two dynamic motions, i.e., a flapping motion in shallow cavities and a rolling-up motion in deep cavities.
Numerical modeling of transient nonlinear water waves generated by horizontally moving bottom disturbances
Authors: Jin Xin , Qin Yi-yi , Tao Yuan , Lin Peng-zhi
Published: November 2024

The study aimed to elucidate transient variations of nonlinear water waves (NWWs) generated by horizontally moving bottom disturbances against the disturbance velocity by using an in-house Navier–Stokes model. The disturbance velocity including the subcritical, transcritical, and supercritical ones, representing various sorts of bottom disturbances, was considered to produce NWWs. Special attention was paid to the wave from higher supercritical regimes, which was rarely reported, and the simulations showed that a stable leading singular precursor soliton would occur because the inertial force came to be localized and meantime predominant over the gravitational force. The results also suggested that: (1) though the bottom forcing was steady, due to the mutual interaction of the gravitational and inertial forces, the generated leading wave was not asymptotically steady but periodic within a disturbance Froude number (Fr) exceeding the transcritical regime; (2) the leading wave could bifurcate to a stable singular precursor soliton at the extensive supercritical regime since the inertial force came to be predominant; (3) wave heights of the leading, prolonging (being negative) and trailing waves within subcritical and transcritical regimes grew with the increasing Fr; (4) the prolonging wave would eventually develop into positive when Fr was sufficiently large, meanwhile, the leading wave turned to a singular precursor soliton for a considerable Fr. Furthermore, the study noted that the free surface configuration was a direct hint of the disturbance regime and phase velocity of the leading wave.
Artificial mechano-nociceptive system based on transparent ITO/AlN/ITO memristor nociceptor neuron
Authors: Ye Caiyang , Xu Yimeng , Dai Ziyi , Zhu Zede , Li Chao , Qian Kai
Published: November 2024

Artificial nociceptors demonstrate significant potential in emerging fields such as intelligent prosthetics, humanoid robotics, and electronic skin, capable of transducing external noxious stimuli to the central nervous system. Unlike common sensory neurons, nociceptors exhibit unique characteristics, including “no adaptation,” “relaxation,” “threshold firing,” and “sensitization of allodynia/hyperalgesia.” This study presents a forming-free volatile transparent ITO/AlN/ITO memristor that emulates biological nociceptor behaviors. Leveraging this artificial nociceptor, an artificial mechano-nociceptive system is developed by integrating the ITO/AlN/ITO memristor into a piezoelectric force sensor system for pain sensing and noxious stimuli warning. This research contributes to the advancement of human cognitive capability emulation and artificial intelligence systems, particularly in the domain of pain perception and response.
How does vortex dynamics help undulating bodies spread odor?
Authors: Kamran Maham , Fardi Amirhossein , Li Chengyu , Khalid Muhammad Saif Ullah
Published: November 2024

In this paper, we examine the coupling between odor dynamics and vortex dynamics around undulating bodies, with a focus on bio-inspired propulsion mechanisms. Utilizing computational fluid dynamics simulations with an in-house immersed boundary method solver, we investigate how different waveform patterns, specifically carangiform and anguilliform, influence the dispersion of chemical cues in both water and air environments. Our findings reveal that vortex dynamics significantly impact the overall trajectory of odor spots, although the alignment between odor spots and coherent flow structures is not always precise. We also evaluate the relative contributions of diffusion and convection in odor transport, showing that convection dominates in water, driven by higher Schmidt numbers, while diffusion plays a more prominent role alongside convection in air. Additionally, the anguilliform waveform generally produces stronger and farther-reaching chemical cues compared to carangiform swimmers. The critical roles of Strouhal number and Reynolds number in determining the efficiency of odor dispersion are also explained, offering insights that could enhance the design of more efficient, adaptive, and intelligent autonomous underwater vehicles by integrating sensory and hydrodynamic principles inspired by fish locomotion.
Numerical study of liquid sloshing in three-dimensional flexible cylindrical tank under multi-directional seismic excitation
Authors: Kha K. Q. N. , Benaouicha M. , Guillou S. S. , Seghir A.
Published: November 2024

The present study aims to evaluate the effect of the flexibility of three-dimensional (3D) cylindrical tank on liquid sloshing inside the tank as well as the influence of the hydrodynamic forces on the structure's deformation. A ground-supported cylindrical flexible tank filled with water and subjected to seismic excitation is investigated using a numerical coupling methodology to take into account the fluid–structure interactions. The Navier–Stokes equations in the fluid domain are solved using the finite volume method, while the finite element method is used to solve the linear-elastic equations of the structure. The arbitrary Lagrangian–Eulerian formulation is applied for the moving mesh in two-phase flow system. The simulations are conducted using free open-source software: OpenFOAM for fluid dynamics and FEniCS for solid mechanics, both utilize the preCICE library for data exchanging and fluid–structure coupling. The numerical methodology is validated by the experimental and numerical results given in literature. A multi-directional earthquake ground motion is then considered as external loading, and the elasticity of the tank wall is varied to investigate the effect on the fluid sloshing. It has been shown that the more flexible the tank walls are, the greater will be both the sloshing height and the structural deformations during an earthquake event. Several flow field information and structural responses have been provided, such as the sloshing height, hydrodynamic pressure, structure deformations, and structural stress distribution. The potential elephant's foot buckling phenomenon at the lower part of tank can also be predicted.
Proxy model of constant-rate mercury intrusion experiment for low-permeability reservoir based on meta-learning
Authors: Zhang Tong , Yan Kun , Meng Lingdong , Feng Zihui , Liu Yikun
Published: November 2024

Pore structure parameters are used to characterize the reservoir pore structure and are crucial for evaluating and developing reservoirs for low-permeability reservoirs. However, traditional experiments to obtain pore structure parameters such as constant-rate mercury injection (CMI) can be time-consuming and expensive. To reduce the cost of obtaining these parameters, this study proposes using meta-learning as a proxy model for CMI experiments. We developed six meta-learning models: gray wolf optimizer extreme learning machine, whale optimization algorithm extreme learning machine (WOA-ELM), moth-flame optimization extreme learning machine, gray wolf optimizer support vector regression, whale optimization algorithm support vector regression, and moth-flame optimization support vector regression. These models were used as proxies for CMI and trained with conventional and experimental rock data to predict porous structure parameters such as average throat radius (ATR), maximum throat radius, variance, relative sorting coefficient (RSC), and uniformity coefficient. We compared our models with ten conventional proxy models. The results indicate that the WOA-ELM achieved the best performance, with an R2 (R-squared) of 90.1%, a mean absolute error of 0.4522, and a root mean square error of 0.3852. Compared to conventional models, this represents an improvement in R2 of 14.66%–30.46%. The meta-learning models also achieved the highest prediction accuracy in average throat radius (with R2 up to 96.58%) and showed an improvement (with R2 up to 91.21%) in relative sorting coefficient and uniformity coefficient, indicating the advantages of the meta-learning model in the prediction of pore homogeneity.
A high-fidelity finite volume scheme for ideal magnetohydrodynamics equations using boundary variation diminishing algorithm
Authors: Pan Chenxi , Song Sheng , Chen Chungang , Li Xingliang , Shen Xueshun , Xiao Feng
Published: November 2024

A high-fidelity finite volume scheme based on the BVD (boundary variation diminishing) principle is proposed in this study to solve ideal magnetohydrodynamics (MHD) equations. A hybrid spatial reconstruction profile, based on a quadratic polynomial and a steepness-adjustable hyperbolic tangent function, is adopted to reproduce accurate solutions of complex magnetohydrodynamics flows. The BVD principle is used to find an optimal combination of these two types of functions by comparing variations between reconstructed interface values. Non-physical oscillations around discontinuities are removed by switching the quadratic polynomial to the step-shaped function. Additionally, an eight-wave method is applied in this study to control divergence errors of the magnetic field. The widely used numerical tests in one- and two-dimensional cases were checked in this study. The proposed scheme can achieve the accuracy of a third-order linear scheme in convergence tests for both advection and MHD equations and capture strong MHD shock waves without spurious oscillations. In comparison with a third-order WENO (weighted essentially non-oscillatory) scheme, the proposed one gains more accurate solutions for not only strong discontinuities but also smooth structures across scales. To our knowledge, this is the first attempt to build a high-fidelity model for ideal MHD equations by the BVD algorithm. Numerical results demonstrate that the BVD algorithm has promising potential to build practical models for various MHD flows.
Study on the differences in microscopic oil displacement effects and action mechanisms of different rhamnolipid systems
Authors: Ma Mengqi , Li Junjian , Hu Jing , Li Jiamu , Dong Lirong , Ding Jialei , Jiang Hanqiao
Published: November 2024

Rhamnolipids are a class of anionic glycolipid surfactants produced through microbial metabolism. As a widely researched biosurfactant, rhamnolipids possess several advantages over traditional chemical surfactants, including non-toxicity, eco-friendliness, biodegradability, and biocompatibility, particularly in the context of microbial oil recovery applications. This class of surfactants enhances oil recovery by reducing the interfacial tension between oil and water, emulsifying residual oil, and modifying the wettability of rock surfaces. Furthermore, rhamnolipids maintain stability in high-temperature and high-salinity environments. However, rhamnolipids derived from different fermentation substrates exhibit variations in structure, composition, and properties, resulting in distinct displacement effects and mechanisms of action. This study focuses on two types of rhamnolipids: typical rhamnolipid and high-yield rhamnolipid, which are fermented using glycerol and rapeseed oil, respectively. Based on the characteristics of the target heavy oil reservoir, micromodels were designed and manufactured to conduct microfluidic experiments. The results obtained from imaging and video recording were analyzed qualitatively and quantitatively to explore the differences in effects and mechanisms between the two rhamnolipid systems. Results indicate that typical rhamnolipid increased recovery by 4.41% through delayed mechanisms involving wettability modification and residual oil emulsification. Conversely, high-yield rhamnolipid demonstrates an immediate effect by reducing interfacial tension, resulting in a recovery increase in 5.68%. According to the observed experimental phenomena and analytical trends, the conclusions evaluate the production increase, clarify the differences in mechanisms of action, and enhance the microscopic understanding of these surfactants. These findings provide directions for future investigations and serve as a reference for the design of related schemes.
Multi-stream encoder and multi-layer comparative learning network for fluid classification based on logging data via wavelet threshold denoising
Authors: Li Hengxiao , Qiao Sibo , Sun Youzhuang
Published: November 2024

In recent years, the importance of fluid classification in oil and gas exploration has become increasingly evident. However, the inherent complexity of logging data and noise pose significant challenges to this task. To this end, this paper proposes a wavelet threshold denoising-based multi-stream encoder combined with multi-level comparison learning (LogMEC-MCL) framework for fluid classification. The framework begins with comprehensive noise reduction, utilizing wavelet threshold denoising to preprocess the data. It then extracts global temporal features by incorporating attention gated recurrent units within the multi-stream encoder. In parallel, multi-scale convolutional neural networks capture local spatial information, ensuring a more complete understanding of the data. To further improve the discriminative power of the extracted features, the framework includes two contrastive learning modules: instance-level contrastive learning and temporal contrastive learning. These components work together to refine feature differentiation, particularly in challenging cases. Additionally, the framework introduces a custom-designed loss function that combines cross-entropy loss with contrastive loss, thereby optimizing the classification performance. The proposed model was rigorously evaluated using a real-world logging dataset from the Tarim Basin in China. The experimental results demonstrate that LogMEC-MCL consistently outperforms current state-of-the-art models on two test datasets, achieving maximum classification accuracies of 95.70% and 95.50%, respectively.
Laboratory study of suspension of sediment mixtures in turbulence generated by multiple oscillating grids
Authors: Li Qijun , Cheng Nian-Sheng
Published: November 2024

Sediment suspension is vital to the geomorphological and ecological processes in rivers. However, previous research has mainly focused on the suspension of sediments with uniform grain sizes, neglecting the complexities arising from sediment mixtures. This study investigates the suspension behaviors of both uniform and mixed-size sediment grains in an oscillating grid turbulence environment. The experimental apparatus comprised a seven-panel grid system, which oscillated at varying frequencies to generate homogeneous turbulence within a water column. The results revealed that for uniform sediments, the sediment diffusion coefficient increases nonlinearly with oscillating frequency and particle size, and for sediment mixtures, the suspension of particles is influenced not only by particle inertial effect but also by the interaction between coarse and fine particles. The presence of coarse grains leads to an enhancement in the sediment diffusion coefficient for fine grains, whereas the reverse influence is minimal. Additionally, the size fraction for the suspended sediment is influenced by various factors, including the oscillating frequency, the height of suspension, and the type of the sediment bed. This study also investigates the mechanisms of sediment-carrying capacity from an energy conservation perspective. It shows that the power required to keep sediment in suspension can be adopted as a new parameter for assessing sediment-carrying capacity. These insights are expected to have broader implications for the comprehension of suspended sediment transport in rivers.
Detection of terahertz radiation using topological graphene micro- nanoribbon structures with transverse plasmonic resonant cavities
Authors: Ryzhii V. , Tang C. , Otsuji T. , Ryzhii M. , Shur M. S.
Published: November 2024

The lateral interdigital array of the graphene microribbons (GMRs) on the h-BN substrate connected by narrow graphene nanoribbon (GNR) bridges serves as an efficient detector of terahertz (THz) radiation. The detection is enabled by the nonlinear GNR elements providing the rectification of the THz signals. The excitation of plasmonic waves along the GMRs (transverse plasmonic oscillations) by impinging THz radiation can lead to a strong resonant amplification of the rectified signal current and substantial enhancement of the detector response. The GMR arrays with the GNR bridges can be formed by the perforation of uniform graphene layers.
Data-driven parameter identification of an equivalent mechanical model for large amplitude liquid sloshing
Authors: Ma Bole , Yan Sen , Upham Michael Paul , Yue Baozeng
Published: November 2024

The accurate extraction of model parameters is vital to ensure that the equivalent mechanical model can precisely describe the dynamic behavior of large amplitude liquid sloshing. In this paper, the parameters of the moving pulsating ball model (MPBM), which is an equivalent mechanical model used to represent the large amplitude liquid sloshing, are extracted using a combination of computational fluid dynamics (CFD), experimental data, and data-driven algorithms. The arbitrary Lagrangian-Eulerian finite element method (ALE-FEM) is adopted to simulate three-dimension large amplitude liquid sloshing in the tank with high precision. The calculated results from the presented algorithm are compared with the experimental data to verify the reliability and validity. The typical parameters required by the MPBM mainly include equivalent sloshing mass, equivalent ball radius, and damping coefficient. These parameters are extracted by using a data-driven parameter optimization algorithm, which is based on the numerical calculation results of ALE-FEM. The accuracy of the MPBM with the equivalent model parameters extracted by using data-driven parameter optimization algorithm is investigated under two types of excitations: harmonic excitation and step excitation. The results show that the MPBM with equivalent model parameters extracted by a data-driven parameter optimization algorithm can precisely imitate the large amplitude liquid sloshing behavior and the method presented can provide significant reference for the overall design of spacecraft dynamics system.
Material heterogeneity as the origin for quasi-elastic ramping and unloading
Authors: Kositski Roman , Miller Tal
Published: November 2024

Plate impact experiments are widely used to study materials under high strain rates and pressures. However, discrepancies often arise when attempting to simulate the free surface velocity at the back of the target, even with modern and advanced material models. This work focuses on two key experimental features: the smooth rise in the elastic precursor wave and the smooth decay of the elastic release wave. We show, through mesoscopic simulations, that these features can be accurately reproduced when material strength heterogeneity is considered. To validate our model, we simulate polycrystalline metals—tantalum and copper—as well as a heterogeneous metallic composite, tungsten heavy alloy. Our results demonstrate that by incorporating mesoscopic strength variations, either due to grain orientation or a composite phase, the smoothed velocity profiles observed experimentally can be simulated while maintaining consistency with uniaxial stress compression tests.
Anisotropic magnetoelectric effect in quasi-one-dimensional antiferromagnet Cu3Mo2O9
Authors: Huang Shuai , Hua Junfan , Su Kunpeng , Yang Lin , Wang Haiou , Li Canglong
Published: November 2024

Using purely electrical methods to manipulate magnetic property poses a significant obstacle in the development of advanced information technology. Multiferroic materials, distinguished by their magnetoelectric (ME) effect, offer a promising way to overcome this challenge by enabling the electric control of magnetic ordering or magnetization. Here, we have synthesized Cu3Mo2O9 single crystals and investigated the anisotropic ME effect within the quasi-one-dimensional spin system. The simultaneous occurrence of ferroelectric (FE) polarization and dielectric anomaly at the Néel temperature (TN) of ∼7.9 K suggests the presence of spin-driven FE property in Cu3Mo2O9. The phase transition temperatures undergo a shift toward lower values for H//c and remain constant for H//a and H//b, indicating anisotropic ME effect. The ME effect demonstrates nonlinear behavior as the magnetic field increases. Near a critical point (T = 7 K and μ0H = 5.6 T), a giant magnetodielectric coupling parameter reaching 374% is observed for H//c, which can be ascribed to the strong spin–phonon coupling and the magnetic field induced change of FE polarization. In the context of charge redistribution without magnetic superlattice, the FE property is analyzed. Moreover, remarkable magnetic control of FE polarization and electric control of magnetization are obtained. The temporal evolution of both polarization and magnetization indicates the stable ME mutual control, suggesting potential applications of Cu3Mo2O9 as a promising multiferroic material.
Ferromagnetic stability optimization via oxygen-vacancy control in single-atom Co/TiO2nanostructures
Authors: Paidi Vinod K. , Lee Byoung-Hoon , Lee Alex Taekyung , Ismail-Beigi Sohrab , Grishaeva Elizaveta , Vasala Sami , Glatzel Pieter , Ko Wonjae , Ahn Docheon , Hyeon Taeghwan , Kim Younghak , Lee Kug-Seung
Published: November 2024

Oxygen vacancies and their correlation with the nanomagnetism and electronic structure are crucial for applications in dilute magnetic semiconductors design applications. Here, we report on cobalt single atom-incorporated titanium dioxide (TiO2) monodispersed nanoparticles synthesized using a thermodynamic redistribution strategy. Using advanced synchrotron-based X-ray techniques and simulations, we find trivalent titanium is absent, indicating trivalent cations do not influence ferromagnetic (FM) stability. Density functional theory calculations show that the FM stability between Co2+ions is very weak. However, electron doping from additional oxygen vacancies can significantly enhance this FM stability, which explains the observed room-temperature ferromagnetism. Moreover, our calculations illustrate enhanced FM interactions between CoTi+ VOcomplexes with additional oxygen vacancies. This study explores the electronic structure and room-temperature ferromagnetism using monodispersed nanocrystallites with single-atom-incorporated TiO2nanostructures. The strategies described herein offer promise in revealing magnetism in other single-atom-incorporated nanostructures.
New estimates of US Civil War mortality from full-census records
Authors: Barceló Joan , Jensen Jeffrey L. , Peisakhin Leonid , Zhai Haoyu
Published: November 2024

The Civil War was the deadliest conflict in US history. However, incomplete records have made it difficult to estimate the exact death toll both nationally, and especially, at the state level. In this article, we leverage the recently released full count of individual census returns and a sample of linked records across multiple censuses to provide i) the most precise national estimate of excess mortality to date and ii) reliable state-level estimates of excess mortality among native-born white males. Our national estimate is 698,000 Civil War deaths. This is substantially higher than the conventional historical estimate of 618,000 but lower than the most recent estimate of around 750,000 deaths based on a 1% census sample. Leveraging a novel migration-adjusted census comparison method, we document the extent to which the war’s toll was much greater in the Confederate states than in the Union.
Understanding secondary school students’ challenges, language learning strategies and future selves at highly selective
EMI schools in Kazakhstan
Authors: Hajar Anas
Published: November 2024

This qualitative study explores the experiences of 22 Grade 11 students, aged 17–18, studying science subjects at
highly selective English medium instruction (EMI) schools. The study is guided by Dörnyei’s L2 Motivational Self System (namely,
the ideal/ought-to L2 self concepts) and Hajar’s (2019) distinction between compulsory
and voluntary strategies. Specific focus was paid to the participants’ English learning challenges, language learning strategies
(LLSs) and future selves. The data were collected from two rounds of semi-structured individual interviews with 22 participants.
The interview data revealed that most students indicated that although it was their parents’ decision to send them to outstanding
English-medium schools, they gradually realised that studying at this type of school fostered their identity formation as users of
English and helped them visualise their ideal end state. This end state related to professional, intercultural and academic gains.
The students reported that they sometimes faced challenges in understanding new terminology in science, along with using English
to answer their teachers’ questions. Despite these challenges, the students exercised their agency by valuing studying in a
resource-rich EMI environment, using certain effective strategies, and receiving fee-charging private tutoring. This study
highlights the importance of understanding language learners’ motivations for attending English private tutoring and how it
impacts their LLS use and future vision. Also, it reveals how educational policy and the distribution of language learning
resources can affect individuals’ LLS choices and use, and their identity development.
Tuning the bandgap and photoluminescence properties of Ge/Al2O3 multilayer thin films using annealing and ion beam irradiation
Authors: Shekhawat Komal , Mittal Priya , Negi Deepak , Shyam Radhe , Prajapat Pukhraj , Gupta Govind , Singh Fouran , Gupta Mukul , Pandey Subingya , Dobbidi Pamu , Nelamarri Srinivasa Rao
Published: November 2024

The present work reports high energy ion beam irradiation induced modifications in Ge/Al2O3 multilayers (MLs). Ge and Al2O3 ML thin films were deposited using the electron beam evaporation technique. Afterward, the as-deposited films were annealed using rapid thermal annealing (RTA) at different temperatures ranging from 500 °C to 800 °C under high vacuum. At a constant fluence of 5 × 1012 ions cm−2, the annealed films were subjected to irradiation with 80 MeV Ag ions. X-ray diffraction patterns show the crystalline nature of films that were annealed above 500 °C, and the increase in crystallite size of Ge nanocrystals from 4.5 to 5.7 nm is observed for annealed samples. After Ag ion irradiation, the crystallinity of the films deteriorates. The crystallinity and optical bandgap are found to vary with Ag ion irradiation. The band gap of annealed films decreased from 1.1 to 0.97 eV with increase in crystallite size. The band gap of irradiated samples increased than that of pristine films. In addition, photoluminescence (PL) measurements were carried out to investigate the luminescence characteristics of annealed and irradiated ML films, and a wide emission band in the visible region was observed. The basic mechanism for tailoring the optical band gap and PL emission using RTA and ion irradiation is discussed.
Marine vibrator using electromagnetic acceleration
Authors: Lin Jun , Chen Guanqiao , Huang Xingguo
Published: November 2024

Optimizing the low-frequency performance of the vibrator is an important direction for the development of marine vibrators. In order to solve the problems of high resonance frequency, small low-frequency displacement and difficulty in generating low-frequency signals of marine vibrators, this study proposed a strategy of high-frequency and low-frequency distributed vibration. In the low-frequency part, electromagnetic acceleration is innovatively combined with the vibrator, and the Ansys Maxwell finite element simulation software is used for analysis. In the high-frequency part, the traditional moving coil vibrator structure is used, and experimental verification is carried out in the anechoic tank. The simulation results show that the low-frequency part of the marine vibrator using electromagnetic acceleration can achieve low-frequency vibration, and the vibration is still relatively stable. The experimental results of the anechoic tank show that within the test frequency band, the sound source level generated meets the requirements of seismic exploration for high-frequency vibrators. This study uses the frequency segmentation strategy to improve the overall working efficiency of the vibrator and provides new ideas for the design of marine vibrators.
A new metrology tool: using transmission Kikuchi diffraction (TKD) to identify and separate nanoparticles for regulatory purposes
Authors: Crouzier Loïc , Feltin Nicolas , Jablon Brooke
Published: November 2024

The development of methods for characterising nanoparticles (NPs) at the nanometric scale is a major challenge facing metrology researchers today. The characterisation of the crystal structure of NPs for regulatory purposes is urgent as mixtures of NPs are frequently found in consumer products and this physicochemical parameter contributes to the understanding of potential health and environmental risks. Using the methods currently available, NPs cannot be individually identified and their size distribution cannot be correlated to crystallographic phases. Instead, a general identification of crystallographic phases is possible. New methods must be developed that identify individual particles on the nanoscale. This paper introduces transmission Kikuchi diffraction, an electron backscattered diffraction (EBSD) technique as a method for comprehensively characterizing a mixture of iron oxide NPs by crystal structure. After identifying the crystal structure of three different iron oxide powders using x-ray Diffraction, the samples were characterised by TKD. The results underline the relevance of TKD, which has sufficient spatial resolution to determine the crystal structure of individual NPs. This study also demonstrates the possibility of electron backscattered diffraction analysis on unpolished samples, something atypical for EBSD and TKD. The powders were then mixed and the individual NPs were correctly identified in a scanning electron microscope (SEM) using TKD. The results show that TKD can be used to correctly identify and classify NPs within a mixture and can be combined with SEM imaging to build size distribution histograms according to the NP crystal structure.
MoS2 photonic synaptic device development for non-invasive detection of Parkinson’s disease
Authors: Divyashree P , B Sharmila , Dwivedi Priyanka
Published: November 2024

The brain-inspired computation using synaptic devices has opened a new avenue for neuromorphic intelligent systems. This paper presents the development of a MoS2 based photonic synaptic devices using wafer-scalable microfabrication for large scale production. The synaptic device was tested using a 450 nm wavelength having a power density of 17 mW cm−2. The test results show that developed devices has enhanced characteristics such as paired pulse facilitation (PPF) index of 307% and long-term retention of 1000 s. The optically stimulated synaptic current was ∼2.5 times higher than the electrically stimulated synaptic current. The potentiation and depression data of the MoS2 device act as the synaptic interface in the artificial intelligence model. The detection of Parkinson’s disease (PD) using voice spectrograms where MoS2 behaves as photonic synapses in two dimensional convolutional neural networks algorithm provided a promising accuracy of 96%. This neuromorphic computing platform for the detection of PD is a next-generation revolution for efficient and smart healthcare solutions.
State estimation of magnetorheological suspension of all-terrain vehicle based on a novel adaptive Sage–Husa Kalman filtering
Authors: Li Wei , Chen Ling , Fu Jie , Luo Lei , Yu Miao
Published: November 2024

For the magnetorheological suspension control system of all-terrain vehicles (ATVs), state estimation is an effective method to obtain system feedback signals that cannot be directly measured by sensors. However, when confronted with modeling errors and sudden changes in sensor noise during complex road driving, conventional estimation methods with fixed parameters encounter challenges in accurately estimating the states of ATV suspension system. To address this issue, this paper introduces a novel adaptive Sage–Husa Kalman filter (ASHKF) algorithm to estimate the sprung and unsprung velocity of ATV suspension system. The algorithm uses exponential weighting function and gradient detection function to adaptively adjust the attenuation coefficient according to the driving conditions of the ATV, thereby realizing real-time correction of the covariance matrix of the prediction error. Ultimately, through simulation and real-vehicle testing, it is demonstrated that the designed ASHKF is able to effectively improve the state estimation accuracy of the speed signal of the suspension system under off-road driving conditions with low-frequency noise and outlying disturbances, and the accuracy is improved by 62.70% compared with that of the conventional Sage–Husa Kalman filter (SHKF).
Creating bandgaps in active piezoelectric slender beams through positive position feedback control
Authors: Kaczmarek Marcin B , HosseinNia S Hassan
Published: November 2024

Bandgaps—frequency ranges with reduced vibration transmissibility in elastic structures, are an opportunity for vibration control originating from the research on elastic metamaterials. In this paper, we study the design for bandgap in slender beams with collocated piezoelectric patch transducers. While creating bandgaps using shunted transducers is a well-established research field, using structures with piezoelectric sensors, actuators, and feedback controllers for the same application has not been thoroughly explored. This paper aims to study the use of the tools originating from the active vibration control (AVC) field for bandgap generation in finite beams with collocated piezoelectric sensors and actuators. Lightly damped second-order low-pass filters are used as controllers in the same configuration as positive position feedback, widely used for active damping. To facilitate the understanding of systems behaviour, we propose a simplified model based on the Euler–Bernoulli beam theory. A modal analysis approach and an assumption of an infinite number of transducers of infinitesimal length distributed along the structure are used to predict the frequency range of the locally resonant bandgap in closed form. The experimental part of the work demonstrates the feasibility of the proposed approach for creating bandgaps in practice. Thanks to the insights from AVC, the control system can be designed purely based on experimental frequency response data without the need for a parametric model of the system. We also show that the uniform distribution of actuators is not necessary for creating bandgap, which can be achieved in a structure with a relatively small number of sparsely placed actuators and compare the obtained results with analytical predictions for ideal metastructure. Low-frequency bandgaps placed between 10 and 320 Hz are obtained in experiments.
Inductance and penetration depth measurements of polycrystalline NbN films for all-NbN single flux quantum circuits
Authors: Zhong Yulong , Zhang Lu , Xie Junjie , Zheng Zengxu , Lu Mingjun , Jin Hua , Wu Ling , Shi Weifeng , Wang Huiwu , Peng Wei , Chen Lei , Wang Zhen
Published: November 2024

In this paper, we report on a systematic study of the inductance and magnetic field penetration depth (λ) of polycrystalline NbN superconducting thin films. By employing a four-metal-layer fabrication process specifically designed for all-NbN single-flux-quantum circuits, we constructed a superconducting quantum interference device loop composed of two parallel NbN SNS junctions, NbN microstrips, and NbN ground planes for precise inductance measurement. At 4.2 K, as the linewidth increases from 1 μm to 30 μm, the inductance per unit length (L
u) of NbN microstrips significantly decreases, for example, the L
u of 250 nm thick NbN microstrips drops from 0.907 pH/μm to 0.047 pH/μm. Compared to Nb, the L
u of polycrystalline NbN microstrips is approximately two to three times that of Nb, offering an advantage for manufacturing smaller superconducting inductors. Furthermore, we conducted simulation analysis using InductEx software to extract the λ of NbN films of varying thicknesses. The results indicate that as the film thickness increased from 45 nm to 600 nm, λ initially decreased sharply and then stabilized, with values ranging from 430 nm to 323 nm. Notably, once the film thickness exceeded 200 nm, λ remained essentially constant, even at a temperature of 10 K, where it showed good stability, albeit with a slight increase (about 50 nm) compared to 4.2 K. This dependence of λ on thickness is reasonably explained by considering the effects of NbN film thickness on the superconducting critical temperature and residual resistivity. These research findings not only deepen our understanding of the characteristics of superconducting films but also lay a solid foundation for the future design and manufacture of more compact superconducting circuits at the higher temperature of 10 K.
Electronic circuit and image encryption using a novel simple 4D hyperchaotic system
Authors: Abed Karam Adel , Al-Azzawi Saad Fawzi , Saber Qasim Omar
Published: November 2024

A new simple 4D autonomous hyperchaotic system with seven terms is introduced. This system was inspired by an unusual 3D chaotic Liu system with six terms. The proposed system has two unstable saddle and saddle-foci points. Theoretical and numerical analyses are conducted to investigate various dynamical features of the system, including its equilibria, Jacobian matrix, Lyapunov exponents, Lyapunov dimension (Kaplan-Yorke), and multistability. The proposed system demonstrates multistability, enhancing its potential for various applications. An electronic circuit implementation using NI Multisim software 14.3 validates the system’s practical feasibility. A novel image encryption algorithm has been developed based on the system’s hyperchaotic properties. Experimental results confirm the algorithm’s robustness in both encryption accuracy and computational efficiency compared to existing methods. As well as, correlation analysis of adjacent pixels in encrypted images yields near-zero or negative values, indicating adequate randomization. The NIST SP800–22 statistical tests confirm the randomness of generated sequences with p-values consistently above 0.01. Information entropy analysis of encrypted images approaches the ideal value. These results demonstrate the proposed system’s effectiveness in secure image encryption, offering a promising solution for multimedia security applications.
Multi-strategy based quantum cost reduction of quantum boolean circuits
Authors: Ahmed Taghreed , Younes Ahmed , Elkabani Islam
Published: November 2024

The construction of quantum computers is based on the synthesis of low-cost quantum circuits. The quantum circuit of any Boolean function expressed in a Positive Polarity Reed-Muller (PPRM) expansion can be synthesized using Multiple-Control Toffoli (MCT) gates. This paper proposes two algorithms to construct a quantum circuit for any Boolean function expressed in a PPRM expansion. The Boolean function can be expressed with various algebraic forms, so there are different quantum circuits can be synthesized for the Boolean function based on its algebraic form. The proposed algorithms aim to map the MCT gates into the NCV gates for any quantum circuit by generating a simple algebraic form for the Boolean function. The first algorithm generates a special algebraic form for any Boolean function by rearrangement of terms of the Boolean function according to a predefined degree of term d

term
, then synthesizes the corresponding quantum circuit. The second algorithm applies the decomposition methods to decompose MCT circuit into its elementary gates followed by applying a set of simplification rules to simplify and optimize the synthesized quantum circuit. The proposed algorithms achieve a reduction in the quantum cost of synthesized quantum circuits when compared with relevant work in the literature. The proposed algorithms synthesize quantum circuits that can applied on IBM quantum computer.
Fixing three dimensional geometries from entanglement entropies of CFT2
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Authors: Wang 王 Peng 鹏 , Wu 伍 Houwen 厚文 , Yang 杨 Haitang 海棠
Published: November 2024

In this paper, we propose a method of fixing the leading behaviors of three dimensional geometries from the dual CFT2 entanglement entropies. We employ only the holographic principle and do not use any assumption about the AdS/CFT correspondence and bulk geometry. Our strategy involves using both UV and IR-like CFT2 entanglement entropies to fix the bulk geodesics. With a simple trick, the metric can be extracted from the geodesics. As examples, we fix the leading behaviors of the pure AdS3 metric from the entanglement entropies of free CFT2 and, more importantly, the BTZ black hole from the entanglement entropies of finite temperature CFT2. Consequently, CFT2 with finite size or topological defects can be determined through simple transformations. Following the same steps, in principle, the leading behaviors of all three dimensional (topologically distinct) holographic classical geometries from the dual CFT2 entanglement entropies can be fixed.