bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural, dielectric, and optical properties based on spinel ferrite (Mn0.5Fe1.5Mg0.5Ni0.5O4) nanoparticles filler reinforced PVA for optoelectronic, laser CUT-OFF filters and energy storage devices
Authors: Rabiea E A , Abouhaswa A S , Abomostafa H M 
Published: October 2023

Abstract
The fabrication of polymer nanocomposites with specialized traits is gaining popularity across the world due to novel added qualities. In this work we used a flash auto-combustion method to prepare Mn0.5Fe1.5Mg0.5Ni0.5O4 nanoparticles and the casting method to prepare Mn0.5Fe1.5Mg0.5Ni0.5O4/PVA nanocomposite polymer films with doping of nanoparticles various from 1–5 wt.%. The effect of Mn0.5Fe1.5Mg0.5Ni0.5O4 nanoparticles addition on the structural, optical, and dielectric characteristics of nanocomposite polymer films was analyzed. The structural properties were studied using x-ray diffraction pattern, high resolution transmission electron microscope, Fourier transform infrared, and field emission scanning electron microscope. The effects of nanoparticles doping on ac conductivity, electric modulus, impedance, and dielectric constant were investigated. It shows that Mn0.5Fe1.5Mg0.5Ni0.5O4/PVA nanocomposite films have higher values of permittivity and ac conductivity than PVA and exhibit lower values of dielectric loss, electric modulus, and impedance. The optical properties showed the indirect optical decreased from 4.8 to 4.4 eV. According to the experimental results, these nanocomposite polymer films show promise for laser CUT-OFF filters and energy storage devices.
Table-like magnetocaloric effect due to field-induced inter-cluster interactions in Eu0.5Sr0.5MnO3–EuMnO3 composites
Authors: Akram Wasim , de h-Óra Muireann , Bansal Manisha , Mukhopadhyay Rajatava , MacManus-Driscoll Judith , Maity Tuhin 
Published: October 2023

Abstract
The table-like behavior of the magnetic entropy change is generally observed in rare-earth-based alloys (e.g. La(Fe,Si)13, Gd50Co45Fe5, Gd56Ni15Al27Zr2, Gd

(
1
−
x
−
y
)

Co
x
Al
y
etc). Here, we report similar table-like behavior in a bulk perovskite Eu0.5Sr0.5MnO3–EuMnO3 composite system with a working temperature span of ∼80 K for a field change of ∼70 kOe. AC susceptibility and time-dependent DC magnetization relaxation measurements confirm the presence of interacting ferromagnetic clusters with a Vogel–Fulcher freezing temperature of

T
0

∼

42.7 K. The Langevin function fittings of the isothermal magnetization curves show a non-monotonous variation of cluster size with temperature. We propose a model for the high-field dependency of the ferromagnetic cluster coupling in the composite system. This widens the transition temperature region of long-range order formation and hence gives rise to the table-like magnetocaloric effect in Eu0.5Sr0.5MnO3–EuMnO3 composite systems.
Flexible dielectric spacer with tunable dielectric properties for metamaterial absorber application
Authors: Chaudhary Kajal , Malik Sudha , Singh Gaganpreet , Bhattacharya Sudeb , Ramkumar J , Ramakrishna S Anantha , Srivastava Kumar Vaibhav 
Published: October 2023

Abstract
The development of a flexible and robust metamaterial absorber is a great motivation for the new generation of microwave absorbers covering any conformal shape. Ceramic–polymer composites with variable dielectric constant within the microwave frequencies are proposed as a flexible middle dielectric spacer (MDS) layer to provide an additional degree of design freedom for metamaterial absorber applications. By varying the dielectric constant of the MDS layer, the resonance band of the metamaterial absorber can be tuned while retaining a low profile in addition to enhancing its electromagnetic performance for transverse magnetic (TM) polarized waves. To formulate these composites, tetragonal structured barium titanate (BaTiO3) powder is selected as an excellent candidate when mixed with elastomer polydimethylsiloxane (PDMS), resulting in high mechanical strength substrates. Experimentally, samples with a range of dielectric permittivity from 2.81 to 5.67 were obtained for a 0%–20% volume fill fraction of BaTiO3 in PDMS. The obtained dielectric permittivities are consistent with the Bruggeman effective medium theory. Utilizing an optimized composition (10% BaTiO3), resulting in

ϵ

r

= 4 substrate, an X-band flexible absorber is designed and fabricated to absorb more than 90% of incident electromagnetic waves within a frequency band of 8.16–12.12 GHz.
Excitonic effects on the optical spectra of TiB2 nanosheets
Authors: Sharma Ashish , Thakur Anupma , Rangra V S 
Published: October 2023

Abstract
Two-dimensional (2D) transition metal borides, have recently attracted tremendous interest and become an emerging class of 2D materials due to their intriguing properties. We report systematic investigation of stability, electronic properties and optical activity of 2D-TiB2 nanosheets using first-principles calculations. By combining elastic and phonon-dispersion calculations, we substantiated the mechanical and dynamic stability of 2D-TiB2 nanosheets. Our results of elastic calculations reveal that addition of an extra layer destroys the auxetic behaviour of monolayer (ML) 2D-TiB2 with significant reduction in the brittleness. Further, based on the spin-polarised electronic structure calculations, we find that a low-dimensional metallic state of ML can be achieved by tuning the distance between the titanium and boron layers. The calculations clearly reveal that metallic nature does not destroys the auxetic behaviour of ML. Subsequently, we investigated the optical response of 2D-TiB2 nanosheets (ML and bilayer (BL)) at the level of density functional theory and many-body perturbation theory. The results obtained by solving Bethe–Salpeter equation (GW+BSE formalism) shows that excitonic effects causes a slight blue-shift in the absorption spectra of the nanosheets with ML being optically active with sharp peaks in infrared (IR) and ultraviolet (UV) regions while BL shows the reduced optical activity across wide range of photon energies spanning the near-IR to UV region. In addition, electronic polarisability of the nanosheet decreases with addition of another layer in ML 2D-TiB2. Further investigation of transition probabilities clearly indicates that the response of ML at Dirac point is tunable by spin–orbital coupling effects which makes these nanosheets promising for spintronic applications. The BL exhibits distinct electronic, and optical properties compared to ML. Our study unravels the structural, elastic, electronic, and optical properties of 2D-TiB2 nanosheets and suggests them as promising candidate for variety of optoelectronic and spintronic applications.
An image zooming method based on the coupling threshold in the wavelet packet transform domain
Authors: Liu Chenhua , Wang Anhong 
Published: October 2023

Abstract
Aiming at the problem of blurring edge and detail information in the process of image zooming, this paper proposes a new method of image zooming based on wavelet packet transform by combining the characteristics of anisotropic diffusion. First, the initial zoomed image with higher resolution is obtained by wavelet transform, and the wavelet packet decomposition is performed to obtain more high-frequency wavelet packet coefficients reflecting image details. Second, due to the existence of noise, the relationship between wavelet packet transform and anisotropic diffusion is obtained by studying the process of wavelet packet threshold denoising, and the expression of coupling threshold based on diffusion function is given and applied to the high-frequency wavelet packet coefficients. Finally, the original image is used as the low-frequency part after passing the soft threshold, and reconstructed with the denoised high-frequency part to obtain the final zoomed image. The traditional zooming algorithms as well as the learning-based zooming algorithms are selected for comparison. The results show that the algorithm in this paper effectively avoids the blurring of edges and details under the premise of ensuring the similarity between the zoomed image and the original image, so that the zoomed image can obtain more high-frequency information, and achieves the purpose of removing the noise as well as enhancing the detailed information of the image. The effectiveness of this paper’s algorithm in edge protection can be seen from the results of the comparison with the deep learning-based zooming algorithms.
Rolling bearing fault diagnosis model based on DSCB-NFAM
Authors: Zhao Xiaoqiang , Guo Haike 
Published: October 2023

Abstract
Machine learning techniques have had great success in fault diagnosis. However, the traditional machine learning methods rely heavily on manual priori knowledge leading to poor fault diagnosis results in rolling bearing fault diagnosis. Deep learning techniques can improve the accuracy of fault intelligent diagnosis with the help of automatic extraction of fault features. In this article, a method of smart fault diagnosis for rolling bearings based on depth-separable convolutional block (DSCB)-non-local feature awareness module (NFAM) is proposed. Firstly, a DSCB is constructed, which can reduce the number of parameters and effectively alleviate the gradient disappearance phenomenon. Then a NFAM is constructed to enhance the global sensing ability while adaptively adjusting the weight of each channel. Further, a feature extraction layer is constructed to extend the fault feature of the input information. Finally, a feature pyramid approach is used to fuse the extracted information for output. The validity of the suggested method is tested on both of the bearing datasets. By comparing with several mainstream intelligent diagnosis algorithms, the results of the experiments show that the proposed method has better advancement under complex conditions such as variable load and variable noise.
High accuracy key feature extraction approach for the non-stationary signals measurement based on NGO-VMD noise reduction and CNN-LSTM
Authors: Xu Fujing , Jing Ruirui , Zhang Yan , Liu Qiang , Wu Yimin A 
Published: October 2023

Abstract
The effective extraction of key features in non-stationary signals measurement is crucial in numerous engineering fields, including fault diagnosis, geological exploration, and state detection. To accomplish a more accurate and efficient extraction of key feature information from non-stationary signals, we design a novel approach based on variational mode decomposition (VMD) optimization by northern goshawk optimization (NGO) algorithm, convolutional neural network (CNN), and long short-term memory network (LSTM). First, NGO is used to optimize multiple intrinsic mode functions of VMD and reconstruct the signal according to the linear correlation method. Subsequently, the features of moving root mean square, moving kurtosis, and upper envelope are calculated, thereby constructing the feature matrix. Finally, the CNN-LSTM model is established with the chosen optimal hyperparameters prior to the training phase. The experimental results demonstrate that the proposed NGO-VMD-CNN-LSTM method, with a high accuracy reaching 98.22%, can more accurately extract the key information of typical non-stationary signals.
Voting models and semilinear parabolic equations
Authors: An Jing , Henderson Christopher , Ryzhik Lenya 
Published: October 2023

Abstract
We present probabilistic interpretations of solutions to semi-linear parabolic equations with polynomial nonlinearities in terms of the voting models on the genealogical trees of branching Brownian motion (BBM). These extend McKean’s connection between the Fisher–KPP equation and BBM (McKean 1975 Commun. Pure Appl. Math.
28 323–31). In particular, we present ‘random outcome’ and ‘random threshold’ voting models that yield any polynomial nonlinearity f satisfying

f
(
0
)
=
f
(
1
)
=
0

and a ‘recursive up the tree’ model that allows to go beyond this restriction on f. We compute several examples of particular interest; for example, we obtain a curious interpretation of the heat equation in terms of a nontrivial voting model and a ‘group-based’ voting rule that leads to a probabilistic view of the pushed-pulled transition for a class of nonlinearities introduced by Ebert and van Saarloos.
Non-invasive imaging of neural activity with magnetic detection electrical impedance tomography (MDEIT): a modelling study
Authors: Mason Kai , Aristovich Kirill , Holder David 
Published: October 2023

Abstract

Objectives. (1) Develop a computational pipeline for three-dimensional fast neural magnetic detection electrical impedance tomography (MDEIT), (2) determine whether constant current or constant voltage is preferable for MDEIT, (3) perform reconstructions of simulated neural activity in a human head model with realistic noise and compare MDEIT to EIT and (4) perform a two-dimensional study in a saline tank for MDEIT with optically pumped magnetometers (OPMs) and compare reconstruction algorithms. Approach. Forward modelling and image reconstruction were performed with a realistic model of a human head in three dimensions and at three noise levels for four perturbations representing neural activity. Images were compared using the error in the position and size of the reconstructed perturbations. Two-dimensional MDEIT was performed in a saline tank with a resistive perturbation and one OPM. Six reconstruction algorithms were compared using the error in the position and size of the reconstructed perturbations. Main results. A computational pipeline was developed in COMSOL Multiphysics, reducing the Jacobian calculation time from months to days. MDEIT reconstructed images with a lower reconstruction error than EIT with a mean difference of 7.0%, 5.5% and 11% for three noise cases representing current noise, reduced current source noise and reduced current source and magnetometer noise. A rank analysis concluded that the MDEIT Jacobian was less rank-deficient than the EIT Jacobian. Reconstructions of a phantom in a saline tank had a best reconstruction error of 13%, achieved using 0th-order Tikhonov regularisation with simulated noise-based correction. Significance. This study demonstrated that three-dimensional MDEIT for neural imaging is feasible and that MDEIT reconstructed superior images to EIT, which can be explained by the lesser rank deficiency of the MDEIT Jacobian. Reconstructions of a perturbation in a saline tank demonstrated a proof of principle for two-dimensional MDEIT with OPMs and identified the best reconstruction algorithm.
Negative frequencies in pulse propagation equations and the double analytic signal
Authors: Aguero-Santacruz Raul , Bermudez David 
Published: October 2023

Abstract
In recent years, the topic of negative frequencies has resurfaced in optics motivated by the optical analogue of Hawking radiation. We discuss the physical meaning of negative frequencies and the conditions under which they are relevant. We review how negative frequencies are treated in current pulse propagation models based on the electric field (EF) and the analytic signal (AS). We focus on experimentally measured signals predicted by the conservation of negative comoving frequency in the nonlinear polarization terms to advance these concepts. We propose a new formalism called the double analytic signal (DAS) which clearly separates negative frequencies from positive ones. Additionally, we reduce this new formalism to the AS to prove their equivalence. Throughout the paper, we present numerical solutions of the unidirectional pulse propagation equation to illustrate the EF, AS, and DAS formalisms and to highlight their differences.
A first principle investigation of electronic, mechanical, optical and transport properties of A2AgAlI6(A = Rb, K, Na) for energy harvesting
Authors: Haq Anwar ul , Ahmad Tasawer Shahzad , Amin Muhammad , Bakar Abu , Afaq A , Ehsan Nimra , Ramay Shahid M , Siddig Abubaker Ahmed 
Published: October 2023

Abstract
The structural, elastic, and optoelectronic properties of cubic double halide perovskites A2AgAlI6 (A = Na, K, Rb) were calculated using the full potential linearized augmented plane wave method. The structural stability of these materials was demonstrated using Goldsmith’s tolerance and modified tolerance. The optoelectronic properties were analyzed using the complex dielectric function and density of states. The potential application of this compound is indicated by the absorption and conduction of light in the visible spectrum. The direct bandgap values of 1.77 eV, 1.74 eV, and 1.64 eV for the compound A2AgAlI6 (A = Rb, K, Na) suggest its usefulness in solar panels. The electrical and thermal conductivities, and Seebeck coefficient of A2AgAlI6 (A = Rb, K, Na) were also determined.
Resilient evaluation algorithm of caesium fountain clock based on robust adaptive observation model
Authors: Wang Xiaobin , Yang Yuanxi , Lin Yuting , Wang Bo , Han Chunhao 
Published: October 2023

Abstract
The caesium fountain clock (CSF) is a primary frequency standard used to define the second, which can greatly improve the autonomous timekeeping ability of laboratories. However, CSF are susceptible to issues such as data interruptions, outliers, and significant fluctuations during operation, ultimately hindering their application in timekeeping. To address these issues, a resilient evaluation algorithm based on a robust adaptive observation model has been proposed. Robust and adaptive factors were introduced into the observation model of the Kalman filter to mitigate abnormal CSF operations. The proposed algorithm was tested through simulations and experiments, which demonstrated significant improvements in the accuracy and stability of the evaluation. As a result, this algorithm effectively reduces the impact of abnormal CSF operations and expands the application scope of CSF in the field of timekeeping.
Bounds on eigenfunctions of quantum cat maps
Authors: Kim Elena , Koirala Robert 
Published: October 2023

Abstract
We study ℓ
∞ norms of ℓ
2-normalized eigenfunctions of quantum cat maps. For maps with short quantum periods (constructed by Bonechi and de Biévre in F Bonechi and S De Bièvre (2000, Communications in Mathematical Physics, 211, 659–686)) we show that there exists a sequence of eigenfunctions u with

∥
u

∥

∞

≳

log
N

−
1

/

2

. For general eigenfunctions we show the upper bound

∥
u

∥

∞

≲

log
N

−
1

/

2

. Here the semiclassical parameter is

h
=

2
π
N

−
1

. Our upper bound is analogous to the one proved by Bérard in P Bérard (1977, Mathematische Zeitschrift, 155, 249-276) for compact Riemannian manifolds without conjugate points.
Accurate ab initio calculations of adiabatic energy and dipole moment: Prospects for the formation of cold Alkaline-Earth-Francium molecular ions ALKE-Fr+ (ALKE = Be, Mg, Ca, and Sr)
Authors: Zrafi Wissem , Hela Ladjimi , Berriche Hamid 
Published: October 2023

Abstract
Alkaline-earth and alkali-metal mixtures have an electronic structure that is perfect for laser cooling. This makes them highly attractive for trapping and laser cooling experiments, allowing the formation of cold molecules. For this object, potential-energy curves and relevant spectroscopic parameters of the low-lying electronic excited states of 1,3Σ+, 1,3Π, and 1,3Δ symmetries of molecular-ion systems composed of alkaline-earth-ion and Francium alkali-metal-atom: ALKE-Fr+ (ALKE = Be, Mg, Ca and Sr), are determined using advanced theoretical technique in quantum chemistry, including a non-empirical pseudopotential, core-valence correlation, large Gaussian basis sets and Full Configuration Interaction (FCI). In order to obtain a more accurate understanding of the electronic structure of these systems, we also determined transition and permanent dipole moments and vibrational properties. Thereafter, the spontaneous and the black-body stimulated transition rates were determined and were employed to calculate lifetimes for all vibrational states of the ground electronic states 11Σ+ of molecular-ions under consideration. For the first and the second excited states, radiative lifetimes were investigated via the Franck–Condon approximation including bound-bound and bound-free transitions. High diagonal structure and large Franck Condon Factor (FCF) values f
00 = 0.987, f
11 = 0.959 and f
22 = 0.919 were obtained for the 11Π (v′ = 0, 1, 2)→ 11Σ+ (v = 0, 1, 2) transition making the BeFr+ system a good candidate for laser cooling. Furthermore, the current results could be used to investigate elastic scattering properties in cold-ion-atom collisions for the first excited states and may help the experimentalists for possible formation, spectroscopy, and photoassociation of cold ion-atom mixtures.
Effects of film thickness on crystal structure, surface topography, optical, and photoelectric properties of Ga2O3 thin film based solar blind photodetectors
Authors: Li Zheng-Nan , Wang Zhao-Cai , Li Chen , Lu Bao-Lin , Yan Wei , Huang Chen-Long , Zhang Tao , Luo Yin-Hong , Zheng Ren-Kui 
Published: October 2023

Abstract

β-Ga2O3 epitaxial thin films with different thicknesses were grown on Al2O3 (0001) substrates by the pulse laser deposition technology. The full width at half maximum of XRD rocking curve, grain size, surface roughness, and optical absorbance (200–300 nm) of the β-Ga2O3 films increase with increasing film thickness. In addition, with increasing film thickness, the adsorption edge presents a red-shift phenomenon, which is accompanied by a slight decrease in the optical band gap (

E

g

). The metal-semiconductor-metal type photodetector made with the 401-nm β-Ga2O3 film shows the maximal photocurrent (1.06 μA @ 10 V), photo-to-dark current ratio (6.96 × 104), responsivity (90 mA W−1), and detectivity (0.5 × 1011 Jones) under 254-nm UV light illumination with a light intensity of 98.4 μW/cm2. Moreover, the 401-nm photodetector displays a small rise time of 0.111/0.561 s and a decay time of 0.046/0.047 s as well as a good stability and repeatability. These findings provide useful reference for the fabrication of β-Ga2O3 film based solar blind ultraviolet photodetectors.
Excellent thermoelectric transport performance in semiconducting hhk-silicene
Authors: Yan Peng , Wu Qihong , Wang Cong , Ding Guangqian , Qin Dan 
Published: October 2023

Abstract
Unlike graphene-like silicene, a recently reported hybrid honeycomb-kagome (hhk) silicene is a semiconductor instead of a gapless Dirac-cone, which has great potential applications in semiconducting devices. Here, using first-principles calculations combined with Boltzmann transport equation, we find that hhk-silicene has high Seebeck coefficient and power factor as arising from the moderate band-gap and low effective mass. Meanwhile, compared to graphene-like silicene, the soften acoustic branches and enhanced anharmonicity lead to the extremely low lattice thermal conductivity, i.e., 0.68 W mK−1 at 300 K. Calculated thermoelectric figure of merit reaches 1.98 at 300 K, which is a recorded value among two-dimensional materials, indicating the potential of hhk-silicene as a thermoelectric material.