bluuebunny/crossref_metadata_2025 huggingface dataset:
Compressibility effects on cavity dynamics and shock waves in high-speed water entry
Authors: Yang Liu , Xiang Junbang , Zhang Shaoxi , Kang Huifeng , Wang Xiaoguang , Xia Weixue
Published: April 2024

The importance of high-speed water entry is acknowledged within the defense industry. This study numerically investigates the water entry of a high-speed rectangle projectile, focusing on cavity dynamics and shock wave generation. A computational model is employed to accurately simulate the intricate fluid dynamics of compressible multiphase flows. This model integrates a dual-phase flow algorithm with a thermally sensitive Tait equation of state for the liquid phase. The primary focus lies in understanding the effects of fluid compressibility on cavity evolution and shock wave propagation across different Froude numbers. The findings reveal that compressibility induces changes in cavity formation size, leading to significant variations in phase composition within the cavity. Furthermore, compressibility enhances the air cushion effect upon surface impact, resulting in delayed water entry and concurrent reduction in projectile drag. Moreover, a prognostic model is proposed, correlating shock pressure with propagation distance, thereby validating theoretical hypotheses advanced by Lee et al. [J. Fluid Struct., 11, 819–844 (1997)].
Construction of the single-diamond-structured titania scaffold—Recreation of the holy grail photonic structure
Authors: Wang Chao , Cui Congcong , Deng Quanzheng , Zhang Chong , Asahina Shunsuke , Cao Yuanyuan , Mai Yiyong , Che Shunai , Han Lu
Published: April 2024

As one of the most stunning biological nanostructures, the single-diamond (SD) surface discovered in beetles and weevils exoskeletons possesses the widest complete photonic bandgap known to date and is renowned as the “holy grail” of photonic materials. However, the synthesis of SD is difficult due to its thermodynamical instability compared to the energetically favoured bicontinuous double diamond and other easily formed lattices; thus, the artificial fabrication of SD has long been a formidable challenge. Herein, we report a bottom–up approach to fabricate SD titania networks via a one-pot cooperative assembly scenario employing the diblock copolymer poly(ethylene oxide)-
block
-polystyrene as a soft template and titanium diisopropoxide bis(acetylacetonate) as an inorganic precursor in a mixed solvent, in which the SD scaffold was obtained by kinetically controlled nucleation and growth in the skeletal channels of the diamond minimal surface formed by the polymer matrix. Electron crystallography investigations revealed the formation of tetrahedrally connected SD frameworks with the space group
Fd

3
¯

m
in a polycrystalline anatase form. A photonic bandgap calculation showed that the resulting SD structure has a wide and complete bandgap. This work solves the complex synthetic enigmas and offers a frontier in hyperbolic surfaces, biorelevant materials, next-generation optical devices, etc.
Estrategias introductoras y tipo de reproducción de las citas directas en el corpus oral PERUSEV
Authors: Repede Doina
Published: April 2024

En las últimas décadas diversos estudios han dado cuenta del amplio abanico de marcos introductores de cita directa en las diferentes variedades del español hablado. Más allá de los verbos dicendi como introductores de cita directa, se ha observado el empleo de la conjunción y, los marcadores discursivos, el adverbio así o la construcción ser de que (De la Mora, 2018; Gallucci, 2018a, 2018b; Gallucci & Vargas, 2015, etc.). En este trabajo buscamos una primera aproximación a las distintas estrategias introductoras de citas directas en el habla de los peruanos residentes en la ciudad de Sevilla, con el fin de conocer cómo se materializa la cita directa en esta variedad de habla, así como el tipo de información que se reproduce. Para lograr estos objetivos, utilizamos 22 entrevistas semiestructuradas que constituyen el corpus oral PERUSEV. El análisis muestra que en nuestros materiales predominan los verbos dicendi y los marcadores nulos como estrategias para introducir el discurso directo. Asimismo, revela la aparición de nuevas formas que no habían sido documentadas en otras variedades de habla hispana. Por tipo de reproducción, se ha observado la presencia, aparte del habla directa del propio hablante o de terceros, también del discurso estereotipado e hipotético.
Scrutinizing job satisfaction during COVID-19 through Facebook
Authors: Liu Fung Ming Christy
Published: April 2024

Due to the advent of social media, translators have started communicating about their work- and non-work-related experiences and associated attitudes on these platforms. COVID-19 accelerated a shift toward a greater reliance upon digital media (Tsao et al. 2021;Wong et al. 2021). This paper uses social media data to examine how Chinese translators and/ or interpreters used their Facebook pages as a channel to express their job dis/satisfaction between January 1, 2020 and December 31, 2022. Conclusions regarding practitioner job satisfaction are based on an analysis of information gathered concerning expressed attitudes on access to expanded networking opportunities, client appreciation, and the acquisition of new knowledge. Practitioners value their role as cultural mediators. COVID-19 introduced unprecedented changes, requiring practitioners to adapt to remote work settings and an increased reliance upon digital tools. Despite income and job security concerns due to the pandemic, practitioners remain committed to delivering quality work.
Faa1 membrane binding drives positive feedback in autophagosome biogenesis via fatty acid activation
Authors: Baumann Verena , Achleitner Sonja , Tulli Susanna , Schuschnig Martina , Klune Lara , Martens Sascha
Published: April 2024

Autophagy serves as a stress response pathway by mediating the degradation of cellular material within lysosomes. In autophagy, this material is encapsulated in double-membrane vesicles termed autophagosomes, which form from precursors referred to as phagophores. Phagophores grow by lipid influx from the endoplasmic reticulum into Atg9-positive compartments and local lipid synthesis provides lipids for their expansion. How phagophore nucleation and expansion are coordinated with lipid synthesis is unclear. Here, we show that Faa1, an enzyme activating fatty acids, is recruited to Atg9 vesicles by directly binding to negatively charged membranes with a preference for phosphoinositides such as PI3P and PI4P. We define the membrane-binding surface of Faa1 and show that its direct interaction with the membrane is required for its recruitment to phagophores. Furthermore, the physiological localization of Faa1 is key for its efficient catalysis and promotes phagophore expansion. Our results suggest a positive feedback loop coupling phagophore nucleation and expansion to lipid synthesis.
A covariant tapestry of linear GUP, metric-affine gravity, their Poincaré algebra and entropy bound
Authors: Farag Ali Ahmed , Wojnar Aneta
Published: April 2024

Motivated by the potential connection between metric-affine gravity and linear generalized uncertainty principle (GUP) in the phase space, we develop a covariant form of linear GUP and an associated modified Poincaré algebra, which exhibits distinctive behavior, nearing nullity at the minimal length scale proposed by linear GUP. We use three-torus geometry to visually represent linear GUP within a covariant framework. The three-torus area provides an exact geometric representation of Bekenstein’s universal bound. We depart from Bousso’s approach, which adapts Bekenstein’s bound by substituting the Schwarzschild radius (

r

s

) with the radius (R) of the smallest sphere enclosing the physical system, thereby basing the covariant entropy bound on the sphere’s area. Instead, our revised covariant entropy bound is described by the area of a three-torus, determined by both the inner radius

r

s

and outer radius R where

r

s

⩽
R

due to gravitational stability. This approach results in a more precise geometric representation of Bekenstein’s bound, notably for larger systems where Bousso’s bound is typically much larger than Bekensetin’s universal bound. Furthermore, we derive an equation that turns the standard uncertainty inequality into an equation when considering the contribution of the three-torus covariant entropy bound, suggesting a new avenue of quantum gravity.
Schwinger correlation of Dirac fields in accelerated frames
Authors: Zeng Hao-Sheng , Liu Heng , Wu Lian-Jie
Published: April 2024

We study the Schwinger correlation of Dirac fields in the noninertial frames under the influences of both constant and pulsed electric fields. We use both the entanglement negativity and quantum mutual information between particle and antiparticle as the indicator of the Schwinger correlation observed by the accelerated observers. We find that the Schwinger correlation in the inertial frames is the largest. With the increase of acceleration of the observers, the Schwinger correlation becomes smaller and smaller, but does not vanish in the limit of infinite acceleration. For the given acceleration, the Schwinger correlation is a nonmonotonic function of the electric field intensity, and there is an optimal value of electric field intensity for which the Schwinger correlation is the largest. In the case of pulsed electric fields, the Schwinger correlation is also the nonmonotonic function of pulsed width, which suggests the existence of optimal pulsed width for observing Schwinger correlation.
Influence of Be vacancy on 2D BeN4 single-layer for enhanced H2S sensing: prediction from first-principles simulations
Authors: Lakshmy Seetha , Banerjee Antara , Sanyal Gopal , Kalarikkal Nandakumar , Chakraborty Brahmananda
Published: April 2024

A notable surge in research interest directed towards the exploration and development of two-dimensional materials, specifically in the realm of advancing nano-devices, with a special focus on applications in gas detection, has been observed. Among these materials, the spotlight has fallen on a newly synthesized single-layered Dirac Semimetal, known as BeN4, which holds great promise as a potential candidate for an efficient gas sensor. The current investigation uses first-principles calculations to examine the H2S detection capability of pristine and point-defect-tempted BeN4 single-layers. The H2S molecule has been observed to be weakly adsorbed on pure BeN4 through weak van der Waals interaction exhibiting very low adsorption energy of −0.0726 eV and insignificant charge transport. The impact of the Be vacancy point defect in BeN4 was the surge in H2S adsorption energy to −0.582 eV, manifested by enhanced charge transmission (0.02 e) from the H2S molecule to the BeN4 with Be defects. The reasonable physical steadiness and modest recovery time (6 ms) at ambient conditions indicate the possibility of Be point-defected BeN4 being a contender as a sensor material for designing and developing a robust H2S gas sensor. In addition, the sensor exhibited a selective response towards the H2S gas molecules. Our findings will provide a reference line for the fabrication of innovative H2S detectors, showcasing the practical implications of the observed enhancements in H2S adsorption energy and charge transmission in Be point-defected BeN4 structures.
Influence of gate dielectric property on the capacitance dispersion in organic-metal-insulator-semiconductor capacitors
Authors: Imroze Fiheon , Chennamkulam Ajith Mithun , Manda Prashanth Kumar , Logesh Karunakaran , Dutta Soumya
Published: April 2024

The capacitance dispersion with frequency in an organic-metal–insulator-semiconductor capacitor (OMISCAP) is a vital phenomenon for predicting high-frequency applications. In this paper, the influence of the dielectric constant on the capacitance dispersion of OMISCAP is investigated by varying the dielectric constant of poly-4-vinyl-phenol using cross-linker concentration. The cut-off frequency of capacitance dispersion f

c

at which the capacitance drops by 10% of the plateau is introduced to measure the capacitance dispersion and the range of operating frequency. The variation of f

c

from 34 kHz to 50 kHz upon changing the dielectric constant of the insulator from 3.8 to 4.8 appears to be due to the combined effect of the capacitance variation in step with dielectric constant and the resistance variation due to field-induced charge accumulation in the semiconductor. The experimental results are validated using TCAD simulation and parameter extraction.
Topological phase transitions with zero indirect band gaps
Authors: Palumbo Giandomenico
Published: April 2024

Topological phase transitions in band models are usually associated to the gap closing between the highest valance band and the lowest conduction band, which can give rise to different types of nodal structures, such as Dirac/Weyl points, lines and surfaces. In this work, we show the existence of a different kind of topological phase transitions in one-dimensional systems, which are instead characterized by the presence of a robust zero indirect gap, which occurs when the top of the valence band coincides with the bottom of the conduction band in energy but not in momentum. More specifically, we consider an one-dimensional model on a trimer chain that is protected by both particle–hole and chiral-inversion symmetries. At the critical point, the system supports a Dirac-like point. After introducing a deforming parameter that breaks both inversion and chiral symmetries but preserves their combination, we observe the emergence of a zero indirect band gap, which results to be related to the persymmetry of our Hamiltonian. Importantly, the zero indirect gap holds for a range of values of the deforming parameter. We finally discuss the implementation of the deforming parameter in our tight-binding model through time-periodic (Floquet) driving.
Higher-order topological phases in crystalline and non-crystalline systems: a review
Authors: Yang Yan-Bin , Wang Jiong-Hao , Li Kai , Xu Yong
Published: April 2024

In recent years, higher-order topological phases have attracted great interest in various fields of physics. These phases have protected boundary states at lower-dimensional boundaries than the conventional first-order topological phases due to the higher-order bulk-boundary correspondence. In this review, we summarize current research progress on higher-order topological phases in both crystalline and non-crystalline systems. We firstly introduce prototypical models of higher-order topological phases in crystals and their topological characterizations. We then discuss effects of quenched disorder on higher-order topology and demonstrate disorder-induced higher-order topological insulators. We also review the theoretical studies on higher-order topological insulators in amorphous systems without any crystalline symmetry and higher-order topological phases in non-periodic lattices including quasicrystals, hyperbolic lattices, and fractals, which have no crystalline counterparts. We conclude the review by a summary of experimental realizations of higher-order topological phases and discussions on potential directions for future study.
Quantum enhanced efficiency and spectral performance of paper-based flexible photodetectors functionalized with two dimensional materials
Authors: Sharma Monika , Mazumder Nirmal , Ajayan Pulickel M , Deb Pritam
Published: April 2024

Flexible photodetectors (PDs) have exotic significance in recent years due to their enchanting potential in future optoelectronics. Moreover, paper-based fabricated PDs with outstanding flexibility unlock new avenues for future wearable electronics. Such PD has captured scientific interest for its efficient photoresponse properties due to the extraordinary assets like significant absorptive efficiency, surface morphology, material composition, affordability, bendability, and biodegradability. Quantum-confined materials harness the unique quantum-enhanced properties and hold immense promise for advancing both fundamental scientific understanding and practical implication. Two-dimensional (2D) materials as quantum materials have been one of the most extensively researched materials owing to their significant light absorption efficiency, increased carrier mobility, and tunable band gaps. In addition, 2D heterostructures can trap charge carriers at their interfaces, leading increase in photocurrent and photoconductivity. This review represents comprehensive discussion on recent developments in such PDs functionalized by 2D materials, highlighting charge transfer mechanism at their interface. This review thoroughly explains the mechanism behind the enhanced performance of quantum materials across a spectrum of figure of merits including external quantum efficiency, detectivity, spectral responsivity, optical gain, response time, and noise equivalent power. The present review studies the intricate mechanisms that reinforce these improvements, shedding light on the intricacies of quantum materials and their significant capabilities. Moreover, a detailed analysis of the technical applicability of paper-based PDs has been discussed with challenges and future trends, providing comprehensive insights into their practical usage in the field of future wearable and portable electronic technologies.
Understanding and optimizing the sensitization of anatase titanium dioxide surface with hematite clusters
Authors: Asikainen Kati , Alatalo Matti , Huttula Marko , Barbiellini B , Assa Aravindh S
Published: April 2024

The presence of hematite (Fe2O3) clusters at low coverage on titanium dioxide (TiO2) surface has been observed to enhance photocatalytic activity, while excess loading of hematite is detrimental. We conduct a comprehensive density functional theory study of Fe2O3 clusters adsorbed on the anatase TiO2 (101) surface to investigate the effect of Fe2O3 on TiO2. Our study shows that TiO2 exhibits improved photocatalytic properties with hematite clusters at low coverage, as evidenced by a systematic study conducted by increasing the number of cluster adsorbates. The adsorption of the clusters generates impurity states in the band gap improving light absorption and consequently affecting the charge transfer dynamics. Furthermore, the presence of hematite clusters enhances the activity of TiO2 in the hydrogen evolution reaction. The Fe valence mixing present in some clusters leads to a significant increase in H2 evolution rate compared with the fixed +3 valence of Fe in hematite. We also investigate the effect of oxygen defects and find extensive modifications in the electronic properties and local magnetism of the TiO2 -Fe2O3 system, demonstrating the wide-ranging effect of oxygen defects in the combined system.
Clutch model for focal adhesions predicts reduced self-stabilization under oblique pulling
Authors: Braeutigam Andrea , Burnet Anton F , Gompper Gerhard , Sabass Benedikt
Published: April 2024

Cell-matrix adhesions connect the cytoskeleton to the extracellular environment and are essential for maintaining the integrity of tissue and whole organisms. Remarkably, cell adhesions can adapt their size and composition to an applied force such that their size and strength increases proportionally to the load. Mathematical models for the clutch-like force transmission at adhesions are frequently based on the assumption that mechanical load is applied tangentially to the adhesion plane. Recently, we suggested a molecular mechanism that can explain adhesion growth under load for planar cell adhesions. The mechanism is based on conformation changes of adhesion molecules that are dynamically exchanged with a reservoir. Tangential loading drives the occupation of some states out of equilibrium, which for thermodynamic reasons, leads to the association of further molecules with the cluster, which we refer to as self-stabilization. Here, we generalize this model to forces that pull at an oblique angle to the plane supporting the cell, and examine if this idealized model also predicts self-stabilization. We also allow for a variable distance between the parallel planes representing cytoskeletal F-actin and transmembrane integrins. Simulation results demonstrate that the binding mechanism and the geometry of the cluster have a strong influence on the response of adhesion clusters to force. For oblique angles smaller than about 40∘, we observe a growth of the adhesion site under force. However this self-stabilization is reduced as the angle between the force and substrate plane increases, with vanishing self-stabilization for normal pulling. Overall, these results highlight the fundamental difference between the assumption of pulling and shearing forces in commonly used models of cell adhesion.
Pressure and temperature dependent ab-initio quasi-harmonic thermoelastic properties of tungsten
Authors: Gong Xuejun , Dal Corso Andrea
Published: April 2024

We present the ab-initio temperature and pressure dependent thermoelastic properties of body-centered cubic tungsten. The temperature dependent quasi-harmonic elastic constants (ECs) are computed at several reference volumes including both the phonon and the electronic excitations contribution to the free energy and interpolated at different temperatures and pressures. Good agreement with the experimental ECs on a single crystal at ambient pressure is found. The pressure and temperature dependence of the shear sound velocity measured on polycrystalline tungsten by Qi et al is also in agreement with theory. Some discrepancies are found instead for the compressional velocity at high temperature and this is attributed to the temperature derivative of the bulk modulus, higher in theory than in experiment. These conclusions are reached both by PBE and by PBEsol functionals. The two give elastic properties with a similar pressure and temperature dependence although the latter is closer to experiment at 0 K.
Laminar separation bubble analysis by means of single–shot lifetime temperature sensitive paint in a water towing tank
Authors: Venenciuc Tudor V , Klein Christian , Yarusevych Serhiy , Hain Rainer , Kähler Christian J
Published: April 2024

A laminar separation bubble is studied on an SD7003 foil in a water towing tank at a Reynolds number of

6
⋅

10
4

and an angle of attack of 6∘ by means of the temperature sensitive paint single-shot lifetime method in order to resolve the footprints and dynamics of vortical structures at low inflow turbulence levels. A heat flux is created by applying a carbon based heating layer on the suction side of the foil. The influence of the surface heating on the transition behaviour is analyzed using 2D2C-PIV and found to be negligible. The results demonstrate the capability of the single-shot lifetime method to quantify salient time-averaged flow characteristics, as well as to resolve and characterize the footprints of the dominant coherent structures.
Internal surface inspection method under linear structured light illumination based on dual non-coaxial optical paths
Authors: Zhang (张芷民) Zhimin , Li (李鹏阳) Pengyang , Huang (黄秋红) Qiuhong , Zhu (朱凌建) Lingjian
Published: April 2024

The inner space of tubular and hole-like workpieces, such as oil pipes and cylinders, is limited in volume and has no effective means of measuring the inner surface under geometric constraints.

This paper proposes a non-coaxial optical path line structured light method for inner surface inspection, which can significantly reduce the device size and working distance. The method constructs two non-coaxial optical paths for light source and imaging, and uses two fixed reflectors to achieve the deflection of the optical axes of the light source and imaging paths.

After theoretical derivation and verification, a sample device was designed and fabricated for experiments. The device measures approximately 22 mm by 24 mm in cross-section, the maximum insertion distance is about 200 mm, and the minimum inner diameter of the accessible space is 50 mm.

The results show that the optical path design does not destroy the original homography relationship, and can still ensure the measurement capability comparable to the existing methods when reducing the device size to 10% of the original. The method has obvious advantages when applied to the inspection of tubular and hole-like workpieces in fields such as petrochemical industry, military equipment, etc.
Improved ellipsoid fitting aided geomagnetic sensor calibration algorithm
Authors: Jiang Wei , Tan Xinglong
Published: April 2024

Aiming at the problems that the traditional single ellipsoid fitting fails to eliminate the errors of the geomagnetic sensor and does not consider the geomagnetic anomaly information, etc., this paper proposes a robust least squares combined with the Levenberg–Marquardt (LM-RLS) algorithm to fit an accurate ellipsoid to achieve accurate data calibration. According to the geomagnetic sensor error model, the total amount of geomagnetism is used as the constraint, the fitted ellipsoid coefficients of RLS are used as the initial values, and the LM algorithm is used to calculate the magnetic field dispersion points to the nearest point of the fitted ellipsoid surface. Then, the initial calibration value is solved by the criterion of the minimum weighted sum of squares of the closest point distance. Finally, the accurate ellipsoid is obtained to realize data calibration. The results of the dynamic experiment show that after the ellipsoid is precisely fitted by the LM-RLS algorithm, the sum of the absolute values of the distance from the magnetic field discrete data to the ellipsoid surface is reduced by 48.33% (RLS) and 43.10% (RWTLS). The relative errors of the magnetic field in the X, Y, and Z axes are reduced from 0.48%, 0.78%, 1.48% (RLS) and 0.30%, 0.58%, 1.14% (RWTLS) to 0.10%, 0.04% 0.16 %, respectively. The accuracy of geomagnetic calibration is improved by 68.06% (RLS) and 61.02% (RWTLS) in the dynamic experiment. The algorithm improves the accuracy of geomagnetic measurement, which provides a new idea for the calibration of three-axis geomagnetic sensors.
A portable terminal for acoustic monitoring and online recognition of bats with CNN-LSTM
Authors: Gao Wenzhuo , Liu Fanghao , Li Chengxuan , Shi Mengyao , Lin Aiqing , Dong Yongjun , Guo Jingfu
Published: April 2024

The acquisition and recognition of ultrasonic signals serves as pivotal mechanisms for the dynamic monitoring of bat species. In this study, we introduce a novel portable terminal for ultrasonic monitoring and online recognition of bats, leveraging an embedded platform in conjunction with the AudioMoth device. This research capitalizes on the distinctive differences observed in the echolocation signals’ typical characteristics across various bat species, alongside their spectrogram features. To this end, a sophisticated voiceprint recognition method was developed, combining the strengths of convolutional neural network with long short-term memory network. This method was subsequently integrated into the portable terminal. Furthermore, the Majority Vote Algorithm was employed to improve the recognition accuracy. Experimental results obtained from trials conducted within a controlled bat laboratory environment demonstrate the terminal’s capability for real-time collection and online recognition of bat ultrasonic signals. Remarkably, the system achieved a recognition accuracy of 99.18%, surpassing the performance metrics of four conventional deep learning models typically employed in similar contexts. This research not only provides a practical case for the acoustic monitoring and recognition of bat species but also holds the potential for broader application in wildlife diversity investigations.
Nonlinear frequency response function: experimental study on gearbox fault detection under step load
Authors: Tang Weili , Liu Deming , Li Xinxin , Mao Hanling , Huang Zhenfeng
Published: April 2024

For rotating machinery, excitation signals are difficult to measure, making it impossible to detect fatigue damage using nonlinear frequency response function. The purpose of this study is to propose a fatigue damage detection method for gearboxes under stepped load conditions based on normalized nonlinear output frequency response functions (NOFRFs). That is, using the vibration signals from the gearbox during the step loading to calculate the cross power spectrum, and therefrom estimating the normalized NOFRFs. This method is used to detect gearboxes containing prefabricated damaged gears or bearings. The research result shows that gear and bearing damage can lead to an increase in the index value of normalized NOFRFs. The different type of damage lead to the significant diversification of higher-order normalized NOFRFs, which further demonstrates that the method proposed in this article is not only effective in gearbox damage detection, but also has certain potential in fault classification. Then, experimental research for accumulated fatigue damage of gear was conducted. The results show that the normalized NOFRFs index is a better indicator of fatigue damage than the kurtosis index.
A multi-frequency magnetic particle spectroscopy system for systematic characterization and highly sensitive detection of magnetic nanoparticles
Authors: Sun Shaoqi , Sun Shijie , Xu Lijun , Zhong Jing
Published: April 2024

Systematic characterization and highly sensitive detection of magnetic nanoparticles (MNPs) is of great importance to investigate the magnetic properties of the MNPs for biomedical applications. In this study, a multi-frequency magnetic particle spectroscopy (MPS) system is developed to measure the magnetic response of the MNPs in different ac magnetic fields. A model for the description of the output signal of the MPS system is deduced to analyze the signal-to-noise ratio of the MNP harmonics. The noise source, including the Gaussian noise and harmonic distortion from the excitation magnetic field, is quantitatively measured and comprehensively analyzed to investigate their influences on the limit-of-detection (LOD) of the MPS system. The MPS signal and dynamic magnetization curve of the MNPs are measured in different ac magnetic fields with the developed MPS system. In addition, a series of MNP samples with different iron concentrations are prepared for experiments to determine the LOD, indicating an LOD of 2.3 ng in terms of iron. The dependence of the LOD on the Gaussian noise and the harmonic distortion is discussed. The present work indicates that one needs to comprehensively consider the influence factors of the Gaussian noise and harmonic distortion to develop a sensitive MPS system with multi-frequency excitation.
Detection and metrology of micro-nano particles through the integration of image and laser modes
Authors: Tao Yikun , He Hu
Published: April 2024

Micro-nano particles are an indispensable component in various industrial and scientific applications. Accurate granular information is critical for manufacturing products involving these particles. This study presents a novel detection method that merges image and laser modes to achieve precise size and shape determination of micro-nano particles. The proposed method integrates adaptive image analysis with laser particle size fitting to ensure accurate feature detection. Experimental results using ternary precursor samples demonstrate that the fusion mode outperforms both the laser and image modes in terms of size and shape accuracy. The errors of D10, D50, and D90 of the fusion mode are 4.89%, 1.88%, and 2.94%, respectively, which are significantly lower than those obtained using the laser or image mode alone. Additionally, the fusion mode retains the particle shape information from the image mode. The fusion model offers a promising approach for dual-mode detection of micro-nano particles, demonstrating enhanced robustness compared to single-mode methods. Furthermore, the study introduces an image processing method based on a BP neural network classification model that accurately classifies and detects agglomerated and non-agglomerated particles. The classification accuracy reaches 94.98%, and the particle size information remains within the acceptable range.
Fully automated operational modal identification based on scale-space peak picking algorithm and power spectral density estimation
Authors: Li Xiao , Dong Yu-Xia , Zhang Feng-Liang
Published: April 2024

Modal analysis is a fundamental and essential research direction in the field of structural engineering. The ultimate goal is to determine the modal parameters of the structures. However, the existing modal analysis algorithms often require a large number of parameter adjustments and manual intervention during operation, which cannot be fully automated. In order to realize the automatic identification of modal parameters, the automatic operational modal identification method (AOMI) is proposed based on the interpolated power spectral density estimation (IPSE). To achieve more precise spectrum analysis in the low-frequency band, IPSE is employed to perform Fourier transform on the original frequency domain segment with optimized frequency resolution. This enhances the sharpness of the obtained spectrum in the low-frequency range, making peak frequencies more discernible. Subsequently, the scale-space peak picking algorithm is used to automatically obtain the peak of the power spectral density (PSD), thus enabling the automatic identification of the natural frequency. Finally, the frequency domain decomposition method (FDD) is used to identify modal parameters based on the natural frequencies. The effectiveness of AOMI is verified through the modal identification of the old steel truss bridge and the three layer framework. Under the environmental excitation, the frequencies identified by the IPSE method is close to that of FDD, Bayesian fast fourier transform (FFT) and covariance driven stochastic subspace identification (SSI-COV). Furthermore, the PSD obtained through IPSE has sharper peak than that of FDD and the Welch’s method. The damping ratio identification accuracy and modal assurance criterion (MAC) are satisfactory in AOMI, which can improve the automatic performance.
Functionalized MBenes as promising anode materials for high-performance alkali-ion batteries: a first-principles study
Authors: Ahmad Sheraz , Xu Hu , Chen Letian , Din H U , Zhou Zhen
Published: April 2024

The discovery of novel electrode materials based on two-dimensional (2D) structures is critical for alkali metal-ion batteries. Herein, we performed first-principles computations to investigate functionalized MXenes, Mo2BT2 (T = O, S), which are also regarded as B-based MXenes, or named as MBenes, as potential anode materials for Li-ion batteries and beyond. The pristine and T-terminated Mo2BT2 (T = O, S) monolayers reveal metallic character with higher electronic conductivity and are thermodynamically stable with an intrinsic dipole moment. Both Mo2BO2 and Mo2BS2 monolayers exhibit high theoretical Li/Na/K storage capacity and low ion diffusion barriers. These findings suggest that functionalized Mo2BT2 (T = O, S) monolayers are promising for designing viable anode materials for high-performance alkali-ion batteries.
Effects of gamma-ray irradiation on material and electrical properties of AlN gate dielectric on 4H-SiC
Authors: Zhu Xiaogang , Shen Zhanwei , Wang Z J , Liu Zhengran , Miao Yuyang , Yue Shizhong , Fu Zhao , Li Zihao , Zhang Yuning , Hong Rongdun , Wu Shaoxiong , Chen Xiaping , Cai Jiafa , Fu Deyi , Zhang Feng
Published: April 2024

This article investigates the radiation effects on as-deposited and annealed AlN films on 4H-SiC substrates under gamma-rays. The AlN films are prepared using plasma-enhanced-atomic-layer-deposition on an n-type 4H-SiC substrate. The AlN/4H-SiC MIS structure is subjected to gamma-ray irradiation with total doses of 0, 300, and 600 krad(Si). Physical, chemical, and electrical methods were employed to study the variations in surface morphology, charge transport, and interfacial trapping characteristics induced by irradiation. After 300 krad(Si) irradiation, the as-deposited and annealed samples exhibit their highest root mean square values of 0.917 nm and 1.190 nm, respectively, which is attributed to N vacancy defects induced by irradiation. Under irradiation, the flatband voltage (V
fb) of the as-deposited sample shifts from 2.24 to 0.78 V, while the annealed sample shifts from 1.18 to 2.16 V. X-ray photoelectron spectrum analysis reveals the decomposition of O-related defects in the as-deposited AlN and the formation of Al(NO
x
)
y
compounds in the annealed sample. Furthermore, the space-charge-limits-conduction (SCLC) in the as-deposited sample is enhanced after radiation, while the barrier height of the annealed sample decreases from 1.12 to 0.84 eV, accompanied by the occurrence of the SCLC. The physical mechanism of the degradation of electrical performance in irradiated devices is the introduction of defects like N vacancies and O-related defects like Al(NO
x
)
y
. These findings provide valuable insights for SiC power devices in space applications.
Real-time imaging reveal anisotropic dissolution behaviors of silver nanorods
Authors: Dong Meng , Pan Yuchen , Zhu Jingfang , Jia Haiyang , Dong Hui , Xu Feng
Published: April 2024

The morphology and size control of anisotropic nanocrystals are critical for tuning shape-dependent physicochemical properties. Although the anisotropic dissolution process is considered to be an effective means to precisely control the size and morphology of nanocrystals, the anisotropic dissolution mechanism remains poorly understood. Here, using in situ liquid cell transmission electron microscopy, we investigate the anisotropic etching dissolution behaviors of polyvinylpyrrolidone (PVP)-stabilized Ag nanorods in NaCl solution. Results show that etching dissolution occurs only in the longitudinal direction of the nanorod at low chloride concentration (0.2 mM), whereas at high chloride concentration (1 M), the lateral and longitudinal directions of the nanorods are dissolved. First-principles calculations demonstrate that PVP is selectively adsorbed on the {100} crystal plane of silver nanorods, making the tips of nanorods the only reaction sites in the anisotropic etching process. When the chemical potential difference of the Cl− concentration is higher than the diffusion barrier (0.196 eV) of Cl− in the PVP molecule, Cl− penetrates the PVP molecular layer of {100} facets on the side of the Ag nanorods. These findings provide an in-depth insight into the anisotropic etching mechanisms and lay foundations for the controlled preparation and rational design of nanostructures.
Investigating air resistance with classroom projectiles
Authors: Johnson Wes
Published: April 2024

The effects of air resistance on ball bearings launched in the Physics classroom are small but measurable. This paper describes a method for modeling the effects of both quadratic and linear air resistance. This method allows students to more accurately predict where their projectiles will land. More importantly, it allows students to explore multiple explanations for the motion they observe.
Atomic line spectra and the conservation laws
Authors: Goh Ker Liang
Published: April 2024

By conservation of linear momentum an atom recoils after it de-excites by giving out a photon. The de-excitation energy is shared by the photon and the recoiling atom. There was no mention in textbooks of this recoil energy when discussing atomic line spectra. We illustrate why it is valid to assume that the de-excitation energy is the energy of the emitted photon in line spectra around the visible light region.
Time-resolved investigations of a glow mode impulse dielectric barrier discharge in pure ammonia gas by means of E-FISH diagnostic
Authors: Jean-Marie-Desiree R , Najah A , Noël C , De Poucques L , Cuynet S
Published: April 2024

Time-resolved electric field strength measurements have been performed, using an electric-field induced second harmonic (E-FISH) diagnostic, in a nanosecond glow discharge of an impulse dielectric barrier discharge, in an ammonia gas environment. A temporal resolution of 2 ns and a spatial resolution estimated at 70 µm (given by laser waist) have been achieved. The comparative study of E-FISH measurements with and without a plasma discharge, operated at 4 kHz, reveal the presence of a persistent counter electric field, which is assumed to be caused by charge accumulation in between the AlN dielectrics used. Furthermore, by studying the influence of the applied voltage, the pressure, and the inter-dielectric distance, measurements seem to indicate the presence of charges remaining also in the post-discharge volume from the previous discharge to the next one.
Enhanced efficiency of deep ultraviolet light-emitting diodes utilizing full-coverage Al reflector and highly reflective Ni/Rh p-electrode
Authors: Lv Zhenxing , Liao Zhefu , Zhou Shengjun
Published: April 2024

Increasing the reflection of p-side is an effective way to improve the optoelectronic performance of flip-chip light-emitting diodes (FCLEDs). Here, we propose a full-coverage Al reflector (FAR) and a highly reflective Ni/Rh p-electrode to enhance the performance of deep ultraviolet (DUV) FCLEDs. The physical mechanism for the impact of the FAR and Ni/Rh electrode on the light extraction efficiency (LEE) is discussed theoretically. Simulations demonstrate that the combination of the FAR and Ni/Rh electrode improves the LEEs of transverse electric- and transverse magnetic-polarized light by 13.62% and 27.08%, respectively. At an injection current of 100 mA, the fabricated DUV FCLEDs with FAR and Ni/Rh electrode exhibits an external quantum efficiency of 4.01% and a wall plugging efficiency of 2.92%, which are 16.85% and 13.18% higher than those of conventional DUV FCLEDs, respectively. These results support the promise of the FAR and Ni/Rh electrode for high-power DUV LED applications.
Exact solutions to the fractional complex Ginzburg-Landau equation with cubic-quintic and Kerr law nonlinearities
Authors: Yang Liu , Gao Ben
Published: April 2024

The fractional complex cubic-quintic Ginzburg-Landau equation (FCCQGLE) with variable coefficients is a propagation model of optical pulses in optical fibers, the quintic term contained in it not only explains the physical significances that are not found in the existing models, but also has more abundant dynamic characteristics compared with lower dimensional systems. In this paper, the exact solutions of this equation are obtained via the appropriate transformations methods, which also are divided into different kinds. More precisely, we acquire the solitary, soliton and elliptic waves solutions by using the improved unified method, the bright and dark solitons solutions by using the improved F-expansion method, as well as the traveling wave solutions through the improved

(
G
′

/

G

2

)

-expansion and Bernoulli sub-equation function methods. Furthermore, we draw the 3D, 2D, density and contour plots to understand the propagation forms and the changes of amplitudes, frequencies and shapes of the solutions for the FCCQGLE with variable coefficients. The last thing worth mentioning is that the improved unified method here extends the degree of the polynomial from n to -n in the hypothetical solutions, which is not appeared before.
Functionalization of morphology in optimization of dielectric, electrical/impedance modulus, and relaxation mechanisms of Co-Ni doped M-type Sr nanoferrites
Authors: Naqvi Sayed Tathir Abbas , Singh Charanjeet , Godara Sachin Kumar , Jotania Rajshree B , Kaur Varinder , Sood Ashwani Kumar
Published: April 2024

In this article, novel M-type hexaferrites SrCoxNixFe12−2xO19 were synthesized using the sol–gel method. The phase structure was characterized by x-ray diffraction, grain morphology was investigated from scanned electron micrographs, and dielectric/electric/impedance characteristics were analyzed in the frequency range of 100 Hz to 2 MHz. X-ray diffraction (XRD) revealed the formation of hexaferrites without any secondary phase. The grain size and distribution were significantly affected by Co-Ni dopants and there was an observation of cluster of grains, grain agglomerates, and improved inter-grain connectivity. The substitution of Co-Ni caused a reduction in crystallite size from 41.47 to 23.14 nm and the dielectric constant/loss tangent varied non-monotonically. The electric modulus indicated a non-Debye type relaxation and the charge transport mechanism exhibited conductivity relaxation to be more dominant than dielectric relaxation. The prepared ferrites show a large dielectric constant and hence are suitable for use in transformer core and storage media. The correlation of simulated grain/grain boundary parameters with morphology, dielectric parameter, and electric modulus has been presented.
Simultaneously probing the sound speed and equation of state of the early Universe with pulsar timing arrays
Authors: Liu Lang , Wu You , Chen Zu-Cheng
Published: April 2024

Recently, several major pulsar timing array (PTA) collaborations have assembled strong evidence for the existence of a gravitational-wave background at frequencies around the nanohertz regime. Assuming that the PTA signal is attributed to scalar-induced gravitational waves, we jointly employ the PTA data from the NANOGrav 15-year data set, PPTA DR3, and EPTA DR2 to probe the conditions of the early Universe. Specifically, we explore the equation of state parameter (w), the reheating temperature (Trh), and the sound speed (cs), findingw= 0.59+0.36-0.40(median + 90% credible interval), andTrh≲ 0.2 GeV at the 95% credible interval for a lognormal power spectrum of the curvature perturbation. Furthermore, we compute Bayes factors to compare different models against the power-law spectrum model, effectively excluding the pressure-less fluid domination model. Our study underscores the significance of scalar-induced gravitational waves as a powerful tool to explore the nature of the early Universe.
The v

R
-philic scalar dark matter
Authors: Xu Xun-Jie , Zhou Siyu , Zhu Junyu
Published: April 2024

Right-handed neutrinos (v

R
) offer an intriguing
portal to new physics in hidden sectors where dark matter (DM) may
reside. In this work, we delve into the simplest hidden sector involving
only a real scalar exclusively coupled to v

R
, referred to
as the v

R
-philic scalar. We investigate the viability of the
v

R
-philic scalar to serve as a DM candidate, under the constraint
that the coupling of v

R
to the standard model is determined
by the seesaw relation and is responsible for the observed DM abundance.
By analyzing the DM decay channels and solving Boltzmann equations,
we identify the viable parameter space. In particular, our study reveals
a lower bound (2.6 × 105 GeV) on the mass of v

R
for
the v

R
-philic scalar to be DM. The DM mass may vary from sub-MeV
to sub-GeV. Within the viable parameter space, monochromatic neutrino
lines from DM decay can be an important signal for DM indirect detection.
Simulations of gravitational heating due to early matter domination
Authors: Ganjoo Himanish , Sten Delos M.
Published: April 2024

In cosmologies with an early matter-dominated era (EMDE) prior to Big Bang nucleosynthesis, the boosted growth of small-scale matter perturbations during the EMDE leads to microhalo formation long before halos would otherwise begin to form. For a range of models, halos can even form during the EMDE itself. These halos would dissipate at the end of the EMDE, releasing their gravitationally heated dark matter and thereby imprinting
a free-streaming cut-off on the matter power spectrum.
We conduct the first cosmological N-body simulations of the formation and evaporation of halos during and after an EMDE.
We show that in these scenarios, the free-streaming cut-off after the EMDE can be predicted accurately from the linear matter power spectrum. Although the free streaming can erase much of the EMDE-driven boost to density perturbations, we use our findings to show that the (re-)formation of halos after the EMDE nevertheless proceeds before redshift ∼ 1000. Early-forming microhalos are a key observational signature of an EMDE, and our prescription for the impact of gravitational heating will allow studies of the observational status and prospects of EMDE scenarios to cover a much wider range of parameters.