bluuebunny/crossref_metadata_2025_split huggingface dataset:
High harmonic generation from Kagome lattice based on multi-band semiclassical trajectory method
Authors: Li Jia , Yu Chao , Peng Yigeng , Lu Ruifeng 
Published: March 2024

Abstract
We develop a multi-band semiclassical trajectory (MBSCT) method for studying the high harmonic generation (HHG) from solids, which is fundamentally similar to the Boltzmann equation but describe the electron density distribution in a different way and can simulate the electron transitions between bands, thereby depicting a richer array of physical processes. Compared to other theoretical methods, such as the time-dependent Schrödinger equation, the semiconductor Bloch equation, and time-dependent density functional theory, our MBSCT method avoids issues like massive consumption of computational resources and the need for wave function phase correction. Moreover, we focus on Kagome-type materials to justify the MBSCT method and investigate the influence of flat band on HHG in strong laser fields. The simulated results show that the intensity of certain harmonic orders is suppressed by the flat band, implying harmonic spectroscopy as a potential all-optical approach for characterising nonequilibrium physics of flat-band quantum materials.
Enhancing ferroelectric performance in hafnia-based MFIS capacitor through interface passivation and bulk doping
Authors: Yang Jianxing , Xie Yufang , Zhu Chengyan , Chen Sixue , Wei Jiajing , Liu Yuan , Chen Mingming , Cao Dawei 
Published: March 2024

Abstract
In recent times, there has been a notable surge of interests in hafnia (HfO2)-based ferroelectrics, primarily due to their remarkable ferroelectric properties employed in ultra-thin configurations, alongside their compatibility with the conventional CMOS manufacturing process. In order to harness the full potential of HfO2-based films for high-performance non-volatile memory applications, it is imperative to enhance their ferroelectric characteristics and durability. This study introduces a straightforward approach aimed at augmenting the ferroelectric performance of Hf
x
Zr1−x
O2 (HZO) films deposited on silicon (Si) substrates through the engineering of oxygen vacancies (V
O). The results of this endeavor demonstrate a significant enhancement in ferroelectric performance, characterized by a 2Pr value of 47 μC cm−2 and impressive endurance, enduring up to 108 cycles under an 8 MV cm−1 electric field without the need of a wake-up process. This marked improvement can be attributed to a dual-pronged approach, involving the incorporation of an Al2O3 interlayer and the introduction of Al atoms into the HZO film. The Al2O3 interlayer primarily serves to mitigate the presence of oxygen vacancies at the interface, while the introduction of Al dopants elevates the concentration of oxygen vacancies within the bulk material. This modulation of oxygen vacancy concentration proves instrumental in facilitating the formation of a ferroelectric o-III phase within the HZO-based films, thereby further augmenting their ferroelectric performance. This innovative and effective strategy offers an alternative avenue for enhancing the ferroelectric properties of materials characterized by a fluorite crystal structure.
Silicon eccentric shell nanoparticles fabricated by template-assisted deposition for Mie magnetic resonances enhanced light confinement
Authors: Yang Huan , Jiang Xinbing , Zhang Manman , Li Ben Q , Wang Jiajie , Han Yiping 
Published: March 2024

Abstract
We report a structure of silicon eccentric shell particles array, fabricated by the SiO2 particles monolayer array assisted deposition of amorphous Si, for high-efficiency light confinement. The SiO2 particles monolayer array is tailored to regulate its interparticle distance, followed by silicon film deposition to obtain silicon eccentric shell arrays with positive and negative off-center distance e. We studied the Mie resonances of silicon solid sphere, concentric shell, eccentric shell and observed that the eccentric shell with positive off-center e supports superior light confinement because of the enhanced Mie magnetic resonances. Spectroscopic measurements and finite difference time domain simulations were conducted to examine the optical performance of the eccentric shell particles array. Results show that the Mie magnetic resonance wavelength can be easily regulated by the size of the inner void of the silicon shell to realize tunable enhanced light confinement. It was found silicon shell with D = 460/520 nm offered high enhanced light absorption efficiency at wavelength of λ = 830 nm, almost beyond the bandgap of the amorphous silicon.
Remote photoplethysmography based on reflected light angle estimation
Authors: Fan Xuanhe , Liu Fangwu , Zhang Jinjin , Gao Tong , Fan Ziyang , Huang Zhijie , Xue Wei , Zhang JingJing 
Published: March 2024

Abstract

Objective. In previous studies, the factors affecting the accuracy of imaging photoplethysmography (iPPG) heart rate (HR) measurement have been focused on the light intensity, facial reflection angle, and motion artifacts. However, the factor of specularly reflected light has not been studied in detail. We explored the effect of specularly reflected light on the accuracy of HR estimation and proposed an estimation method for the direction of specularly radiated light. Approach. To study the HR measurement accuracy influenced by specularly reflected light, we control the component of specularly reflected light by controlling its angle. A total of 100 videos from four different reflected light angles were collected, and 25 subjects participated in the dataset collection. We extracted angles and illuminations for 71 facial regions, fitting sample points through interpolation, and selecting the angle corresponding to the maximum weight in the fitted curve as the estimated reflected angle. Main results. The experimental results show that higher specularly reflected light compromises HR estimation accuracy under the same value of light intensity. Notably, at a 60° angle, the HR accuracy (ACC) increased by 0.7%, while the signal-to-noise ratio and Pearson correlation coefficient increased by 0.8 dB and 0.035, respectively, compared to 0°. The overall root mean squared error, standard deviation, and mean error of our proposed reflected light angle estimation method on the illumination multi-angle incidence (IMAI) dataset are 1.173°, 0.978°, and 0.773°. The average Pearson value is 0.8 in the PURE rotation dataset. In addition, the average ACC of HR measurements in the PURE dataset is improved by 1.73% in our method compared to the state-of-the-art traditional methods. Significance. Our method has great potential for clinical applications, especially in bright light environments such as during surgery, to improve accuracy and monitor blood volume changes in blood vessels.
Self-bound liquid droplets in one-dimensional optical speckle potentials
Authors: Abbas Karima , Boudjemâa Abdelâali 
Published: March 2024

Abstract
We present a comprehensive description of the equilibrium properties of self-bound liquid droplets in one-dimensional optical speckle potentials at both zero and finite temperatures. Using the Bogoliubov theory we calculate analytically the equation of state, fluctuations induced by disorder, and the equilibrium density. In particular, we show that the peculiar competition between the speckle disordered, the interactions and the Lee-Huang-Yang quantum fluctuations may strongly affect the stability and the formation of the self-bound droplet. We address also the static and dynamical properties of such a disordered droplet using the generalized disorder-dependent Gross-Pitaevskii equation. Notably, impacts of a weak speckle potential are treated numerically for both small droplets of an approximately Gaussian shape and large droplets with a flat-top plateau.
Controllable Floquet topological phases in the magnetic ladder system
Authors: Wang Xu-Jin , Zhang Lu , Yan Liang , Yan Jie-Yun 
Published: March 2024

Abstract
Utilizing both the electric and magnetic fields to manipulate electron dynamics enables the external control of topological states. This study investigates the topological characteristics of a quasi-one-dimensional ladder lattice subjected to a time-periodic electric field and a constant magnetic field. The Floquet topological phases are determined in the high-frequency approximation. In the absence of a magnetic field (φ = 0), the energy band diagram is modulated by the electric field parameter

α

/

ℏ
ω

, leading to a topological phase transition when

α

/

ℏ
ω

crosses the value of 1. When a magnetic field is present (

ϕ
=
π

), the topological phase transitions in the ladder model are influenced by both the electric field parameter

α

/

ℏ
ω

and the perpendicular hopping t
0, resulting in a diverse range of adjustable topological states. These discoveries offer promising prospects for the utilization of ladder lattice systems with externally modifiable topological properties.
Structure and magnetic properties of FeSiAl-based composites with the compound passivation agent
Authors: Tong Shanlin , Li Weijian , Qian Yuetong , Jiang Yawei , Liu Yongsheng 
Published: March 2024

Abstract
FeSiAl soft magnetic composites (SMCs), which are widely used in electromagnetic applications, have good electromagnetic characteristics. To reduce their core loss, the current research focuses on improving the properties of insulating coating materials. In this work, different contents of phosphoric acid and chromic acid compound passivating agents are used to prepare the insulation coating of FeSiAl powder. The results revealed that the surface film layer of the powder coating with the compound passivation agent is relatively smooth, and the film layer is too thin to be detected by XRD. With the increase of the amount of passivating agent, the permeability of powder decreases gradually and the performance of anti-DC-Bias loading improved. The core loss shows a trend that it decreases first and then increases with the increase of passivating agent dosage. If the amount of passivator is too much, the core loss will increase rapidly. When a 2% passivator is used, the magnetic permeability of the powder is 72, the DC-Bias characteristic is 51.3% with 100 Oe, and the core loss is 57 mW cm−3 at 100 kHz and 50 mT.
Characterizing SU(1,1) nonclassicality via variance
Authors: Li Huihui , Li Nan , Luo Shunlong , Zhang Yue 
Published: March 2024

Abstract
We quantify the nonclassicality of quantum states associated with the Lie group SU(1,1) by regarding states as observables and considering their variances in the SU(1,1) Perelomov coherent states. Combining the resolution of identity induced by the SU(1,1) Perelomov coherent states, we propose a quantifier for nonclassicality of a state based on the average uncertainty (variance) of the state (regarded as an observable) in the SU(1,1) Perelomov coherent states. This quantifier is easy to calculate and possesses several operational interpretations. We reveal its basic properties and illustrate it by several prototypical examples.
Ar plasma-engraved rGO/In2O3 hollow nanospheres with rich oxygen vacancies for enhanced triethylamine detection
Authors: Guo Lanlan , Zeng Hua , Zhao Wei , Yang Yingli , Wang Guodong , Liu Xiaolian , Wang Yan , Yang Xueli 
Published: March 2024

Abstract
We successfully constructed a high-performance In2O3 based triethylamine sensor using rGO combined with Ar plasma treatment (Ar-rGO/In2O3). The Ar plasma treatment and rGO doping did not cause significant changes to the crystal structure of In2O3 hollow nanospheres, but increased the content of oxygen vacancies in In2O3, while making the structure of In2O3 hollow nanospheres more porous and thin-walled. The gas sensitivity test results show that this new Ar-rGO/In2O3 based sensor has the advantages of high response (Ra/Rg = 172 to 100 ppm, 4.2 times that of pure In2O3 material), low detection limit (0.5 ppm), fast response speed (1 s), and good stability to triethylamine. It also has excellent selectivity, repeatability, and long-term stability. This work is of great significance for understanding the relationship between response and surface oxygen vacancies of sensitive materials, as well as promoting the development of new triethylamine sensors.
Thickness-related variation in the structure, morphology and optical characteristics of nickel thin films for neutral density filtering
Authors: Yadav Mini , Yadav Sandeep , Shankar Ajay , Bala Renu , Rani Mamta 
Published: March 2024

Abstract
In this paper we fabricate neutral density filter (NDF) for the visible region on the Borosilicate glass substrate at room tempreature. E-Beam coating unit is used for fabrication of Nickel thin film on the Borosilicate glass substrate under high vacuum. XRD measurement examined the amorphous growth of thin film at low thickness (t = 10 nm) while higher thickness supported crystalline growth. The Crystallite size (D) and lattice strain (
ϵ
) is decreasing with increasing the thickness. Microstructural investigation by atomic force microscope (AFM) revealed that surface roughness is decreasing with increasing of thickness i.e. From 0.018 to 0.008 nm. The decreasing of roughness prevents scattering loss in neutral density filter. Optical transmittance spectra are obtained using UV–visible spectrophotometer. Nickel 70 nm thickness is an optimum thickness to achieve high optical density (OD = 2.5) but neutrality is poor for higher thickness of filter. Hence the spectral variation of thin filters in our case 10 nm has least spectral variation (ΔOD = 0.11) for stable and durable NDF.
Frequency-domain image encryption based on IWT and 3D S-box
Authors: Wen Heping , Feng Zhaoyang , Bai Chixin , Lin Yiting , Zhang Xiangyu , Feng Wei 
Published: March 2024

Abstract
Most of the existing spatial domain image encryption techniques suffer from the difficulty of resisting cryptographic attacks. For this reason, this paper proposes a frequency-domain based digital image encryption scheme by combining Integer Wavelet Transform (IWT), three-dimensional S-box and chaotic system. First, the plaintext image is decomposed into different frequency subbands by IWT to map the digital image from spatial domain to frequency domain. Second, the plaintext hash value is selected as the dynamic key, and dynamic chaotic pseudo-random sequences with associations are generated, which are used for the encryption of each module respectively. Then, a three-dimensional S-box is designed to encrypt the information-rich low-frequency information using ‘bit-permutation three-dimensional S-box replace ciphertext interleaved diffusion’, while the high-frequency information is encrypted using a lightweight ‘XOR-row column permutation’ operation. Finally, the secure ciphertext for public channel transmission is obtained by the reconstruction method. The scheme of this paper, the frequency domain transformation is implemented through IWT, which enhances the ability to resist attacks. In addition, the diffusion encryption modules employ the introduction of ciphertext interleaved diffusion and parallel encryption mechanisms, thus the algorithm has the ability to resist plaintext attacks. Theoretical analysis and empirical results show that the algorithm has excellent numerical statistical analysis results, which corroborate that it has good confusion, diffusion and avalanche effects, and is able to resist various common cryptographic attacks. The frequency domain image encryption scheme proposed in this paper is a preferred high-security digital image privacy protection technique, so it has good application prospects.
Bouncing pNGB dark matter via a fermion dark matter
Authors: Sáez Bastián Díaz , Contreras Patricio Escalona 
Published: March 2024

Abstract
In addition to the Standard Model, the introduction of a singlet complex scalar field that acquires vacuum expectation value may give rise to a cosmologically stable pseudo-Nambu-Goldstone boson (pNGB), a suitable dark matter (DM) candidate. This work extends this scenario
by including a second cosmologically stable particle: a fermion singlet. The pNGB and the new fermion can be regarded as DM candidates simultaneously, both interacting with the Standard Model through Higgs portals via two non-degenerate Higgs bosons. We explore the thermal freeze-out of this scenario, with particular emphasis on the increasing yield of the pNGB before it completely decouples (recently called Bouncing DM). We test the model under collider bounds, relic abundance, and direct detection, and we explore some indirect detection observables today.
On the absence of ghosts in quadratic bigravity
Authors: Gialamas Ioannis D. , Tamvakis Kyriakos 
Published: March 2024

Abstract
An extension of the bimetric theory of gravity is considered that includes quadratic Ricci
curvature terms associated with each metric. The issue of the Boulware-Deser ghost is
analyzed. The Hamiltonian constraint is derived and the existence of a secondary constraint is
shown, proving that the theory is ghost-free.
NSTX-U research advancing the physics of spherical tokamaks
Authors: Berkery J.W. , Adebayo-Ige P.O. , Al Khawaldeh H. , Avdeeva G. , Baek S-G. , Banerjee S. , Barada K. , Battaglia D.J. , Bell R.E. , Belli E. , Belova E.V. , Bertelli N. , Bisai N. , Bonoli P.T. , Boyer M.D. , Butt J. , Candy J. , Chang C.S. , Clauser C.F. , Corona Rivera L.D. , Curie M. , de Vries P.C. , Diab R. , Diallo A. , Dominski J. , Duarte V.N. , Emdee E.D. , Ferraro N.M. , Fitzpatrick R. , Foley E.L. , Fredrickson E. , Galante M.E. , Gan K.F. , Gerhardt S. , Goldston R. , Guttenfelder W. , Hager R. , Hanson M.O. , Jardin S.C. , Jenkins T.G. , Kaye S.M. , Khodak A. , Kinsey J. , Kleiner A. , Kolemen E. , Ku S. , Lampert M. , Leard B. , LeBlanc B.P. , Lestz J.B. , Levinton F.M. , Liu C. , Looby T. , Lunsford R. , Macwan T. , Maingi R. , McClenaghan J. , Menard J.E. , Munaretto S. , Ono M. , Pajares A. , Parisi J. , Park J-K. , Parsons M.S. , Patel B.S. , Petrov Y.V. , Podestà M. , Poli F. , Porcelli M. , Rafiq T. , Sabbagh S.A. , Sánchez Villar Á. , Schuster E. , Schwartz J. , Sharma A. , Shiraiwa S. , Sinha P. , Smith D. , Smith S. , Soukhanovskii V.A. , Staebler G. , Startsev E. , Stratton B. , Thome K.E. , Tierens W. , Tobin M. , Uzun-Kaymak I.U. , Van Compernolle B. , Wai J. , Wang W. , Wehner W. , Welander A. , Yang J. , Zamkovska V. , Zhang X. , Zhu X.L. , Zweben S. 
Published: March 2024

Abstract
The objectives of NSTX-U research are to reinforce the advantages of STs while addressing the challenges. To extend confinement physics of low-A, high beta plasmas to lower collisionality levels, understanding of the transport mechanisms that set confinement performance and pedestal profiles is being advanced through gyrokinetic simulations, reduced model development, and comparison to NSTX experiment, as well as improved simulation of RF heating. To develop stable non-inductive scenarios needed for steady-state operation, various performance-limiting modes of instability were studied, including MHD, tearing modes, and energetic particle instabilities. Predictive tools were developed, covering disruptions, runaway electrons, equilibrium reconstruction, and control tools. To develop power and particle handling techniques to optimize plasma exhaust in high performance scenarios, innovative lithium-based solutions are being developed to handle the very high heat flux levels that the increased heating power and compact geometry of NSTX-U will produce, and will be seen in future STs. Predictive capabilities accounting for plasma phenomena, like edge harmonic oscillations, ELMs, and blobs, are being tested and improved. In these ways, NSTX-U researchers are advancing the physics understanding of ST plasmas to maximize the benefit that will be gained from further NSTX-U experiments and to increase confidence in projections to future devices.
Numerical investigations on the effect of asymmetric inlet conditions on the performance variations of centrifugal compressor
Authors: Li Xing , Huang Ning , Zhang Jie , Zhang Yanli , Tong Ding , Zhao Yang 
Published: March 2024

Abstract
The high adoption frequency of inlet bent pipes result in variations between the operating performance and design value. In this paper, the performance of centrifugal compressor while adopting two inlet bent pipes, i.e., Pz and Pu, are simulated through the verified simulation method, respectively, and the flow field characteristics of inlet pipes are analyzed and quantitatively characterized. The analysis shows that centrifugal compressor’s performance with Pz and Pu both decrease to a certain degree. The flow field of symmetric swirling distribution both occurred on the outlet plane of Pz and Pu, and the circumferential distortion degree of plane (PCD) with Pz and Pu shows an increasing trend as the flow rate increases. The PCD of Pz with different rotational speed are always higher than that of Pu. The degradation degree of centrifugal compressor’s performance of Pz and Pu both increase with the increasing of PCD, and it is higher by adopting Pz, the pressure ratio degradation degree reaches 6.82% while it reaches 7.38% in efficiency degradation degree. It is found that there is a power law relation between the degradation degree of pressure ratio and PCD, and an exponential relationship between the efficiency degradation degree and PCD.
Experimental investigation of flow instability evolution in a low-speed two-stage axial compressor
Authors: He Rong , Dou Xiangyuan , Liu Yongwen , Wang Tong 
Published: March 2024

Abstract
A low-speed two-stage axial flow compressor with inlet guided vane was tested. Based on its performance, the near-stall condition was determined. The transient pressure signals on the casing wall were obtained along the circumferential and axial directions. Data statistics method was applied to analyze the features of the pressure signals on the working conditions. The variance of pressure increased along streamwise direction under the large flow rate condition. Meanwhile, it was influenced by the interaction between the stator and the rotor at the inlet of the second stage as well. On the near-stall condition, a modal wave like signal was found in time domain, whose frequency was about 47% of the impeller rotation frequency, accompanied with a broad-band feature in the low-frequency region. The first-stage rotor was found to stall with the analysis on the variance of the pressure. While there was no obvious unstable character observed in the second stage, the parameter at the inlet of the second stage revealed that the disturbance generated in the first stage was suppressed by the second stage. These signals’ features could be used to predict the appearance of instability in the two-stage axial flow compressor.