bluuebunny/crossref_metadata_2025_split huggingface dataset:
GaN MSM structure UV photodetector detector based on nonplanar Si substrate and its performance optimization
Authors: Jiang Hang-Hui , Zhang Yan , Li Xue , Luo Yuan-Hang , Wen Chao , Xing Ya-kun , Xiao Meng-Zhen , Li Xin-Jian 
Published: August 2022

Abstract
Silicon (Si) based gallium nitride (GaN) possesses great development potential in fabricating integrated photodetectors. Nevertheless, the large lattice and thermal mismatch between Si and GaN usually brings about high-density dislocations and other line defects, which as a whole will seriously affect the responsiveness, working stability and service life of Si-based GaN (GaN/Si) devices. In this paper, we report that a GaN/Si ultraviolet photodetector (UV PD) with a metal-semiconductor-metal structure was prepared, using silicon nanoporous pillar array (Si-NPA) as nonplanar substrates. It will be shown that high-quality GaN/Si can be prepared and further improved by subsequent annealing treatment, by means of a three-dimensional stress release process brought about by using patterned Si substrates. Under a bias voltage of 1 V, the responsivity, specific detectivity, external quantum efficiency and rise/decay time of the detector were 71.4 mA·W−1, 7.1 × 108 Jones, 24.3% and 0.2/7.6 s, respectively. The results demonstrate that growing GaN on patterned Si substrates might be an effect route for constructing high-performance GaN/Si UV PDs.
Design, analysis and experiments of a stick-slip piezoelectric actuator working under the self-deformation mode
Authors: Yang Zhixin , Zhou Xiaoqin , Huang Hu 
Published: August 2022

Abstract
In this paper, the self-deformation mode of the stick-slip principle was proposed, and accordingly a piezoelectric actuator based on the self-deformation mode was designed, which could achieve stable bidirectional outputs with long stroke. To increase the stepping displacement of the output end and reduce the structural stress, an arc-shape flexible hinge with variable section was employed as the output part of the flexible hinge mechanism. The self-deformation motion was obtained by the deformation of the driving mechanism caused by the reaction force of the mover in the driving process. The stepping and self-locking characteristics of the actuator under various initial gaps were tested, and the evolution of stepping characteristics with the driving voltage, frequency and external load was analyzed. The experimental results showed that by the self-deformation mode, the long stroke with good linearity could be easily achieved for both the forward and reverse motions, and the maximum self-locking force reached 5 N. Furthermore, the maximum driving speed reached 2754 μm s−1 under the driving voltage of 120 V.
Effect of Be and P doping on the electron density, electrical and optoelectronic conduct of half-Heusler LiMgN within ab initio scheme
Authors: Ziat Younes , Zarhri Zakaryaa , Belkhanchi Hamza , Ifguis Ousama , Cano Andrés Domínguez , Lazrak Charaf 
Published: August 2022

Abstract
The effect of (Be- and P-) dopant has been investigated on the electronic structure and optoelectronic properties of LiMgN alloy, where the (Be and P) amount is 6.25%. The LiMgN alloy has an
XYZ
form which is crystallized in the

F

4

¯

3
m

(N° 216) space group. The ‘X
and
Y
’ are being substituted by Be and
Z
is substituted by P. The present investigation is carried out within the Wien2K package inside the TB-mBJ approximation. The present findings show that the Burstein–Moss (BM) shift is observed when Be is being in the Li position, and the Fermi level lies inside the CB. The ‘apparent band gap’ of Be doped LiMgN semiconductor is increased as the absorption edge is pushed to higher energies as a result of some states close to the CB being populated. This conduct is significant, as it gives a chance to get different optical characteristics for the same material and the ‘apparent band gap’ is equal to the actual band gap plus Burstein–Moss (BM) shift. The transmittance T(%) of Be element in the
Y
site is 76%. For the P doped LiMgN, the transmittance is 73%.
Third order nonlinearity and optical power limiting studies of PS/ZnO nanocomposite foils for photonic applications
Authors: Barala Monika , Maidur Shivaraj R , Mohan Devendra , Sanghi Sujata 
Published: August 2022

AbstractThe present work focuses on the preparation of Polystyrene (PS) and PS/ZnO nanocomposite foils by solution casting method and study their structural and nonlinear optical (NLO) characterizations. The Zinc Oxide (ZnO) nanoparticles were synthesized by Sol-gel method. Structural analysis of the prepared nanocomposite foils was carried out by x-ray diffraction (XRD) with an estimated average crystallite size of 27.33 nm. UV–vis-NIR spectra reveal that the nanocomposite foils are transparent in the visible region. FESEM micrographs show the surface morphology of the prepared nanocomposite foils. Energy Dispersive x-ray Spectroscopy (EDX) of the prepared foils confirmed the compositional and spatial distribution of the elements. The NLO properties such as nonlinear absorption coefficient (β), nonlinear index of refraction (n2), and third-order nonlinear susceptibilityχ3were investigated by Z-scan technique at a wavelength of 532 nm and 200 mW with field intensityI0=5.43KWcm−2.The values ofβwere found to bein the order of ∼ 10−7cm W−1, n2in the order of ∼10−12cm2W−1andχ3in the range 4.99 × 10−7– 38.7 × 10−7e.s.u. Further, the optical power limiting threshold was calculated to be 3.646 KW cm−2for 8 wt % of PS/ZnO nanocomposite foil which is a better candidate to act as an optical limiter. The figure of merit has also been determined that establishes the suitability of nanocomposite foils for optical limiting and/or optical switching applications in the visible region.
Doppler boosting the stochastic gravitational wave background
Authors: Cusin Giulia , Tasinato Gianmassimo 
Published: August 2022

AbstractOne of the guaranteed features of the stochastic gravitational wave background (SGWB) is the presence of Doppler anisotropies induced by the motion of the detector with respect to the rest frame of the SGWB source. We point out that kinematic effects can be amplified if the SGWB is characterised by large tilts in its spectrum as a function of frequency, or by sizeable intrinsic anisotropies. Hence we examine the possibility to use Doppler effects as complementary probes of the SGWB frequency profile. For this purpose we work in multipole space, and we study the effect of kinematic modulation and aberration on the GW energy density parameter and on its angular power spectrum. We develop a Fisher forecast analysis and we discuss prospects for constraining parameters controlling kinematically induced anisotropies with future detector networks. As a case study, we apply our framework to a background component with constant slope in frequency, potentially detectable by a network of future ground-based interferometers. For this specific example, we show that a measurement of kinematic anisotropies with a network of Einstein Telescope and Cosmic Explorer will allow us to constrain the spectral shape with a precision of about 16%. We also show that, if a reconstruction of the spectral shape is done via other methods, e.g. frequency binning, a study of kinematic anisotropies can allow one to constrain our peculiar velocity with respect to the CMB frame with a precision of 30%. Finally, we identify cosmological and astrophysical scenarios where kinematic effects are enhanced in frequency ranges probed by current and future GW experiments.
Distinguishing Dirac vs. Majorana neutrinos: a cosmological probe
Authors: Hernandez-Molinero Beatriz , Jimenez Raul , Peña Garay Carlos 
Published: August 2022

AbstractCosmic background neutrinos (CνB) helicity composition is different for Dirac or Majorana neutrinos making detectors based onCνBcapture sensitive to the nature of neutrinos. We calculate, for the first time, the helicity changes of neutrinos crossing dark matter fields, to quantitatively calculate this effect on the capture rate. We show that a fraction of neutrinos change their helicity, regardless of them being deflected by a void or a dark matter halo. The average signal from the 100 most massive voids or halos in a Gpc3gives a prediction that if neutrinos are Dirac, the density of theCνBbackground measured on Earth should be 48 cm-3for left-helical neutrinos, a decrease of 15% (53.6 cm-3; 5%) for a halo (void) with respect to the standard calculation without including gravitational effects due to large scale structures. In terms of the total capture rate in a 100 g tritium detector, this translates in 4.9+1.1-0.8neutrinos per year for the Dirac case, as a function of the unknown neutrino mass scale, or 8.1 per year if neutrinos are Majorana. Thus although smaller than the factor two for the non-relativistic case, it is still large enough to be detected and it highlights the power of futureCνBdetectors, as an alternative to neutrinoless double beta decay experiments, to discover the neutrino nature.
Duality-symmetric axion electrodynamics and haloscopes of various geometries
Authors: Le Dai-Nam , Hoang Le Phuong , Xuan Cao Binh 
Published: August 2022

Abstract
Within the dual symmetric point of view, the theory for seeking axion dark matter via haloscope experiments is derived by exactly solving the dual symmetric axion electrodynamics equation. Notwithstanding that the conventional theory of axion electrodynamics presented in [9,11] is more commonly used in haloscope theory, we show that the dual symmetric axion electrodynamics has more advantages to apply into haloscope theory. First, the dual symmetric and conventional perspective of axion electrodynamics coincide under long-wavelength approximation. Moreover, dual symmetric theory can obtain an exact analytical expression of the axion-induced electromagnetic field for any states of axion. This solution has been used in conventional theory for long-wavelength approximation. The difference between two theories can occur in directional axion detection or electric sensing haloscopes. For illustrative purposes, we consider the various type of resonant cavities: cylindrical solenoid, spherical solenoid, two-parallel-sheet cavity, toroidal solenoid with a rectangular cross-section, and with a circular cross-section. The resonance of the axion-induced signal as well as the ratio of the energy difference over the stored energy inside the cavity are investigated in these types of cavity.
On the effective metric of axial black hole perturbations in DHOST gravity
Authors: Langlois David , Noui Karim , Roussille Hugo 
Published: August 2022

AbstractWe study axial (or odd-parity) perturbations about static and spherically symmetric hairy black hole (BH) solutions in shift-symmetric DHOST (Degenerate Higher-Order Scalar-Tensor) theories. We first extend to the family of DHOST theories the first-order formulation that we recently developed for Horndeski theories. Remarkably, we find that the dynamics of DHOST axial perturbations is equivalent to that of axial perturbations in general relativity (GR) evolving in a, distinct, effective metric. In the particular case of quadratic DHOST theories, this effective metric is derived from the background BH metric via a disformal transformation. We illustrate our general study with three examples of BH solutions. In some so-called stealth solutions, the effective metric is Schwarzschild with a shifted horizon. We also give an example of BH solution for which the effective metric is associated with a naked singularity.
Lepton asymmetric universe
Authors: Kawasaki Masahiro , Murai Kai 
Published: August 2022

AbstractThe recent observation of4He implies that our universe has a large lepton asymmetry. We consider the Affleck-Dine (AD) mechanism for lepton number generation. In the AD mechanism, non-topological solitons called L-balls are produced, and the generated lepton number is confined in them. The L-balls protect the generated lepton number from being converted to baryon number through the sphaleron processes. We study the formation and evolution of the L-balls and find that the universe with large lepton asymmetry suggested by the recent4He measurement can be realized.
Effect of near



-symmetric potentials on nonlinear modes for higher-order generalized Ginzburg–Landau model
Authors: Lin Da , Dong Kai-Ru , Zhang Jia-Rui , Shen Yu-Jia 
Published: August 2022

Abstract
In this paper, we study the higher-order generalized Ginzburg–Landau model which contributes to describing the propagation of optical solitons in fibers. By means of the Hirota bilinear method, the analytical solutions are obtained and the effect of relevant parameters is analyzed. Modulated by the near parity-time-symmetric potentials, the nonlinear modes with 5% initial random noise are numerically simulated to possess stable evolution. Furthermore, the evolution of nonlinear modes is displayed through the adiabatical change of some parameters. The investigation of the present work is intended as a contribution to the work for the higher-order generalized Ginzburg–Landau model.
Faint Space Debris Detection Algorithm Based on Small Aperture Telescope Detection System
Authors: Jiang Ping , Liu Chengzhi , Kang Zhe , Yang Wenbo , Li Zhenwei 
Published: August 2022

Abstract
Ground-based optical observation has unique advantages in space target observation. However, due to the weak light-gathering ability of small-aperture optoelectronic observation telescopes, the space debris in the image is weak and easily drowned in noise. In order to solve the above problems, we use digital image processing technology to extract faint space debris. We propose a high detection rate space debris automatic extraction algorithm, aiming to automatically detect space debris. We first establish a new space target description model. Our algorithm is mainly divided into two stages. The purpose of the first stage is to reduce the influence of a large number of stars. We perform wavelet transform and guided filtering for three consecutive frames, and the reconstructed wavelet that takes the median value can achieve the effect of eliminating stars. In the second stage, we adopt the method of robust principal component analysis and attribute the problem of target detection to the problem of separating the target and background of a single frame of image. After a large number of experimental results analysis, it is proved that the algorithm can effectively detect faint debris in the monitoring system of small aperture telescope, and has high precision and low computational complexity.
Decoding working memory-related information from repeated psychophysiological EEG experiments using convolutional and contrastive neural networks
Authors: Żygierewicz Jarosław , Janik Romuald A , Podolak Igor T , Drozd Alan , Malinowska Urszula , Poziomska Martyna , Wojciechowski Jakub , Ogniewski Paweł , Niedbalski Paweł , Terczynska Iwona , Rogala Jacek 
Published: August 2022

Abstract

Objective. Extracting reliable information from electroencephalogram (EEG) is difficult because the low signal-to-noise ratio and significant intersubject variability seriously hinder statistical analyses. However, recent advances in explainable machine learning open a new strategy to address this problem. Approach. The current study evaluates this approach using results from the classification and decoding of electrical brain activity associated with information retention. We designed four neural network models differing in architecture, training strategies, and input representation to classify single experimental trials of a working memory task. Main results. Our best models achieved an accuracy (ACC) of 65.29 ± 0.76 and Matthews correlation coefficient of 0.288 ± 0.018, outperforming the reference model trained on the same data. The highest correlation between classification score and behavioral performance was 0.36 (p = 0.0007). Using analysis of input perturbation, we estimated the importance of EEG channels and frequency bands in the task at hand. The set of essential features identified for each network varies. We identified a subset of features common to all models that identified brain regions and frequency bands consistent with current neurophysiological knowledge of the processes critical to attention and working memory. Finally, we proposed sanity checks to examine further the robustness of each model’s set of features. Significance. Our results indicate that explainable deep learning is a powerful tool for decoding information from EEG signals. It is crucial to train and analyze a range of models to identify stable and reliable features. Our results highlight the need for explainable modeling as the model with the highest ACC appeared to use residual artifactual activity.
Defects minimisation promoted by lead-volatility in (Pb,La)(Zr,Ti)O3ferroelectric ceramics
Authors: Silva A C , Mendez-González Y , Lima E C , Guerra J D S 
Published: August 2022

AbstractLa-modified PbZrTiO3ferroelectric ceramics with Pb0.92La0.08(Zr0.686Ti0.294)O3nominal composition were obtained via the conventional solid-state reaction method, by considering different PbO excess (5, 10 and 15 mol %). The structural properties, were investigated from X-ray diffraction (XRD) and Raman Spectroscopy techniques, both at room temperature. Results confirmed the formation of the perovskite structure with rhombohedral symmetry (R3mspace-group) for all the samples. The dielectric properties were also investigated, from the temperature dependence of the dielectric response, and results revealed the characteristic response of ferroelectric materials for all the compositions. The obtained very broad peak in the maximum dielectric permittivity, around Tm (~107°C), suggests the diffuse character of the ferroelectric-paraelectric phase transition.
Investigating the Structural and Electronic Properties of LiMO2 (M: Mn, Ni, Co) as Potential Cathode Materials: A DFT Study
Authors: Tsebesebe N.T. , Kgatwane K.M. , Ledwaba R.S. , Ngoepe P.E. 
Published: August 2022

Abstract
The layered transition metal oxides formulated LiMO2 (M: Mn, Ni and Co) are a state-of-art cathode material for lithium-ion batteries. They have attracted considerable attention due to their capability to optimize the capacity, cyclic rate, electrochemical stability, and lifetime. This paper reports the DFT+U calculations performed on LiMnO2, LiNiO2 and LiCoO2 materials. The heats of formations predict that the LiNiO2 is the most thermodynamically stable material while the LiMnO2 is the least thermodynamically stable material. The energy bandgap for LiNiO2 is relatively small suggesting that the material is high in conductivity. Conversely, the energy bandgaps of LiMnO2 and LiCoO2 are relatively wide suggesting that the materials are low in electrical conductivity. All independent elastic constants are positive and satisfying the mechanical stability criterion. Lastly, the phonon dispersion curves display imaginary vibration along high symmetry direction for LiCoO2. However, the material is inferred stable with support from the elastic constants. The LiNiO2 is the most stable material and LiCoO2 is the least stable material.
Alexandrite: investigation of a natural material for radiation dosimetry
Authors: Trindade N M , Nunes M C S , Dardengo S L , Silva A O , Kunzel R , Ulsen C , Yoshimura E M 
Published: August 2022

Abstract
In this work we performed experimental analyses of the dose-response curves of natural alexandrite, using thermoluminescence (TL) and optically stimulated luminescence (OSL). The natural alexandrite crystals from Bahia, Brazil, were pulverized and the optical absorption measurements were carried out in the range of 200 to 800 nm, comparing a non-irradiated sample with a 10 Gy beta irradiated one. OSL and TL measurements were performed using the Risø equipment (model DA-20) with irradiation doses from 1 to 5 Gy. Glow curve analysis was done using GlowFit software for TL, and R Studio software for OSL measurements. The irradiated sample (10 Gy) shows an absorption spectrum similar to the non-irradiated one, containing the same bands. The samples of natural alexandrite showed a linear dose-response for both OSL and TL measurements. From the TL and OSL analyses, it was possible to infer a correlation between the slow OSL component with the most intense TL peaks of alexandrite.
Surface net heat flux estimated from drifter observations
Authors: Wu Lingwei , Wang Guihua 
Published: August 2022

Abstract
The ocean mixed layer temperature equation is used to estimate the surface net heat flux from drifter measurements. The net heat flux is determined for both the climatologic and tropical cyclone (TC) conditions. The spatial distributions of the drifter-derived heat fluxes under both the two conditions are similar to those derived from satellite observations. However, the drifter-derived climatologic heat flux appears to be weaker in magnitude than that derived from satellites, and performs better in closing the energy budget with a global mean value of 3.9 W m−2. The drifter-derived heat flux also performs better than the satellite-derived heat flux under TCs, using the buoy observations as a reference considering metrics such as the meen error, mean absolute error, root mean-square error and percent bias. The spatially averaged mean net heat flux derived from drifters under TCs is −124 W m−2 at 10° N, and decreases to −85 W m−2 at 30° N, however, these values are much larger than those obtained from satellites (−63 W m−2 and −21 W m−2, respectively). As additional components for the mixed layer temperature equation, both the entrainment velocity and eddy diffusivity in climatology show large amplitudes in regions with strong currents such as the Western Boundary Current and Antarctic Circumpolar Current. However, under TC conditions large values of the entrainment velocity and eddy diffusivity mostly appear in regions with strong winds.
Screen-printed, erasable mask on filter membrane for silver nanowires patterning and application in flexible electroluminescent devices
Authors: Wang Jiayi , Lin Yong , Yuan Wei , Su Wenming , Cui Zheng 
Published: August 2022

Abstract
Silver nanowires (AgNWs) have been widely used in transparent conductive films (TCFs) for wearable optoelectronic devices due to their high transmittance, high conductivity. Mask-assisted vacuum filtration is a straightforward and effective patterning strategy for AgNWs with high aspect ratio. However, currently reported non-erasable masks result in the filter membrane being unable to be recycled, which greatly increase the manufacturing cost of patterned TCFs. Herein, we propose an improved method to construct an erasable mask on the filter membrane by screen printing polyvinyl alcohol (PVA) solution. The printed PVA mask is strongly attached to the filter membrane, which lead to the AgNWs pattern with smooth and distinct edges after vacuum filtration. The deposited AgNWs patterns can be transferred to the polydimethylsiloxane film by hot pressing to prepare the patterned TCFs. After the transfer, the printed PVA mask can be easily erased or cleaned from the filter membrane in hot water without damaging its pore structure, enabling the recycling of the filter membrane. As a proof, ten pieces of TCFs with square shape were prepared by recycling one filter membrane and all of them had excellent consistency in sheet resistance, optical transmittance and bending durability. Alternating current electroluminescence devices made from the TCFs were consistent in luminance, emission spectrum and Commission Internationale de l’eclairage coordinates. The erasable mask technique can be extended to patterning process of various nanomaterials other than AgNWs under vacuum filtration to enhance the utilization efficiency of filter membrane and to reduce the manufacturing cost.