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Photometric and spectroscopic study of Ten low Mass Ratio Contact Binary systems:Orbital stability,O'Connell Effect and Infrared Calcium line Filling

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Research in Astronomy and Astrophysics 2024年第8期24卷 212-222页

作者： surjit s.Wadhwa Adam Popowicz Raúl Michel Petar Kostić Oliver Vince Nick F.h.Tothill Ain Y.De horta Miroslav D.Filipović school of science Western Sydney UniversityLocked Bag 1797PenrithNSW 2751Australia Department of Electronics Electrical Engineering and MicroelectronicsSilesian University of TechnologyAkademicka 1644120 GliwicePoland Instituto de Astronomía UNAM.A.P.87722800 EnsenadaBCMéxico Astronomical Observatory Volgina 711060 BelgradeSerbia

low mass ratio contact binary systems are more likely to have unstable orbits and potentially *** addition,such systems exhibit characteristics such as starspots and high energy emissions(UV)suggestive of chromospheric and magnetic *** curve modeling of ten contact binary systems is *** were found to be of extreme low mass ratio ranging from 0.122 to 0.24 and three were found to be potentially unstable and possible merger *** of the infrared calcium absorption lines is a marker of increased chromospheric *** use the available large sky Area Multi-Object Fiber spectroscopic Telescope spectra along with matched standard spectra(broadened for rotation)to measure the excess filling of the central core depression flux of the two main infrared calcium absorption linesλ8542 andλ*** find that all reported contact binaries have excess filling of the core flux in the infrared calcium *** of the systems reported were also observed by the Galaxy Evolution Explorer mission and we find that all three have features of excess ultraviolet emissions further adding evidence for increased chromospheric activity in low mass ratio contact *** of both orbital stability and absorption line filling is dependent on the determination of geometric and absolute parameters from light curve *** an insignificant number of contact binary light curves exhibit the O’Connell effect,usually attributed to *** discuss the inclusion of starspots in light curve solutions and how they influence the geometric and absolute parameters.

关键词： (stars)binaries eclipsing-techniques photometric-stars chromospheres

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saliency-guided meta-hallucinator for few-shot learning

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science China(Information sciences) 2024年第10期67卷 189-210页

作者： hongguang ZhANG Chun lIU Jiandong WANG linru MA Piotr KONIUsZ Philip h.s.TORR lin YANG systems Engineering Institute Academy of Military Sciences Data61 Commonwealth Scientific and Industrial Research Organisation Australian National University Oxford University

learning novel object concepts from limited samples remains a considerable challenge in deep learning. The main directions for improving the few-shot learning models include(i) designing a stronger backbone,(ii) designing a powerful(dynamic) meta-classifier, and(iii) using a larger pre-training set obtained by generating or hallucinating additional samples from the small scale dataset. In this paper, we focus on item(iii) and present a novel meta-hallucination strategy. Presently, most image generators are based on a generative network(i.e., GAN) that generates new samples from the captured distribution of images. however, such networks require numerous annotated samples for training. In contrast, we propose a novel saliency-based end-to-end meta-hallucinator, where a saliency detector produces foregrounds and backgrounds of support images. such images are fed into a two-stream network to hallucinate feature samples directly in the feature space by mixing foreground and background feature samples. Then, we propose several novel mixing strategies that improve the quality and diversity of hallucinated feature ***, as not all saliency maps are meaningful or high quality, we further introduce a meta-hallucination controller that decides which foreground feature samples should participate in mixing with backgrounds. To our knowledge, we are the first to leverage saliency detection for few-shot learning. Our proposed network achieves state-of-the-art results on publicly available few-shot image classification and anomaly detection benchmarks, and outperforms competing sample mixing strategies such as the so-called Manifold Mixup.

关键词： few-shot learning saliency detection object recognition anomaly detection computer vision

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Kinetics of dense plasma in the field of short laser pulses:A generalized approach

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Matter and Radiation at Extremes 2024年第5期9卷 87-92页

作者： V.A.Astapenko V.s.lisitsa Moscow Institute of Physics and Technology(National Research University) Institutskii per.9141701 DolgoprudnyiRussia National Research Centre“Kurchatov Institute ”123182 MoscowRussia National Research Nuclear University MEPhI 115409 MoscowRussia

A generalized kinetic model of atomic level populations in an optically dense plasma excited by laser pulses of arbitrary duration is formulated and *** model is based on a nonstationary expression for the probability of excitation of an atomic transition and takes into account the effects of laser pulse penetration into an optically dense medium.A universal formula for the excitation probability as a function of time and propagation length is derived and applied to the case of a lorentzian spectral profile of an atomic transition excited by a laser pulse with a Gaussian *** features of nonstationary excitation probabilities are presented for different optical depths of the plasma,laser pulse durations,and carrier *** formulas derived here will be useful for the description of atomic populations excited by laser pulses under realistic conditions of dense plasmas.

关键词： laser excitation excited

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Engineering of efficient visible light photocatalysts:Ti_(1-x+y)Cu_(x)la_(y)O_(2)(x=0.03;y=0,0.005,0.01) compositions

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Journal of Rare Earths 2024年第3期42卷 497-505,I0003页

作者： s.M.Yakout A.M.Youssef Inorganic Chemistry Department National Research Centre(NRC)El Buhouth StDokkiCairo12622Egypt

In dye-photocatalysis, widening the wavelengths absorption range of catalysts as well as aborting the recombination of the photoexcited charge carriers(electrons-holes pairs) are of paramount *** the current study, we report the photocatalytic characteristics of four compositions composed of TiO_(2),Ti_(0.97)Cu_(0.03)O_(2), Ti_(0.965)Cu_(0.03)la_(0.005)O_(2)and Ti_(0.96)Cu_(0.03)la_(0.01)O_(2)powders for two harmful dyes(Congo red and methylene blue). The X-ray diffraction technique verified the configuration of mixed anatase and rutile phases in pure TiO_(2)and Ti_(0.97)Cu_(0.03)O_(2)powders while Ti_(0.965)Cu_(0.03)la_(0.005)O_(2)and Ti_(0.96)Cu_(0.03)la_(0.01)O_(2)powders possess anatase phase only. The changes of the band gap structure and dimensions of the unit cell volume of TiO_(2)confirm the substitution of Ti^(4+)sites by Cu^(2+)and la^(3+)ions. Remarkable widening of wavelengths absorption with formation of long absorption tails were found in TiO_(2)(3.13 e V) through insertion of la^(3+)plus Cu^(2+)ions. Ti_(0.965)Cu_(0.03)la_(0.005)O_(2)and Ti_(0.96)Cu_(0.03)la_(0.01)O_(2)samples exhibit a visible light band gap of 2.3 and 2.7 e V, respectively. Based on sEM images, incorporation of Cu^(2+)and la^(3+)ions influences the surface morphology of TiO_(2). The resulting Ti_(0.97)Cu_(0.03)O_(2), Ti_(0.965)Cu_(0.03)la_(0.005)O_(2)and Ti_(0.96)Cu_(0.03)la_(0.01)O_(2)powders present enhanced photocatalytic activity towards Congo red dye degradation compared to pure one under natural solar spectrum. The best Ti_(0.96)Cu_(0.03)la_(0.01)O_(2)catalyst exhibits superior photocatalytic activity of 96% for 10 ppm CR dye in 20 min as well as above average photocatalytic efficiency of 63% for 30 ppm CR dye in 120 min. As well, it showed acceptable photodegradation activity of 52% for 30 ppm MB solution in 140 min of sunlight irradiation. The heightened photodegradation efficiency of Ti_(0.96)Cu_(0.03)la_(0.01)O_(2)catalyst can be clarified in terms of higher ch

关键词： semiconductor TiO_(2) Rare earths Congo red Methylene blue solar spectrum Photodegradation

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Nonlinear wave dispersion in monoatomic chains with lumped and distributed masses:discrete and continuum models

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Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 633-648页

作者： E.GhAVANlOO s.El-BORGI school of Mechanical Engineering Shiraz UniversityShiraz 71963-16548Iran Mechanical Engineering Program Texas A&M University at QatarDoha 23874Qatar

The main objective of this paper is to investigate the influence of inertia of nonlinear springs on the dispersion behavior of discrete monoatomic chains with lumped and distributed *** developed model can represent the wave propagation problem in a non-homogeneous material consisting of heavy inclusions embedded in a *** inclusions are idealized by lumped masses,and the matrix between adjacent inclusions is modeled by a nonlinear spring with distributed ***,the model is capable of depicting the wave propagation in bi-material bars,wherein the first material is represented by a rigid particle and the second one is represented by a nonlinear spring with distributed *** discrete model of the nonlinear monoatomic chain with lumped and distributed masses is first considered,and a closed-form expression of the dispersion relation is obtained by the second-order lindstedt-Poincare method(lPM).Next,a continuum model for the nonlinear monoatomic chain is derived directly from its discrete lattice model by a suitable continualization *** subsequent use of the second-order method of multiple scales(MMs)facilitates the derivation of the corresponding nonlinear dispersion relation in a closed *** novelties of the present study consist of(i)considering the inertia of nonlinear springs on the dispersion behavior of the discrete mass-spring chains;(ii)developing the second-order lPM for the wave propagation in the discrete chains;and(iii)deriving a continuum model for the nonlinear monoatomic chains with lumped and distributed ***,a parametric study is conducted to examine the effects of the design parameters and the distributed spring mass on the nonlinear dispersion relations and phase velocities obtained from both the discrete and continuum *** parameters include the ratio of the spring mass to the lumped mass,the nonlinear stiffness coefficient of the spring,and the wave amplitude.

关键词： nonlinear mass-spring chain discrete model continuum model lindstedtPoincare method(lPM) method of multiple scales(MMs) dispersion phase velocity

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Enhanced entropy generation and heat transfer characteristics of magnetic nano-encapsulated phase change materials in latent heat thermal energy storage systems

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 1051-1070页

作者： P.s.REDDY P.sREEDEVI Department of Mathematics Rajeev Gandhi Memorial College of Engineering and TechnologyNandyal 518501India

The objective of the current study is to investigate the importance of entropy generation and thermal radiation on the patterns of velocity,isentropic lines,and temperature contours within a thermal energy storage device filled with magnetic nanoencapsulated phase change materials(NEPCMs).The versatile finite element method(FEM)is implemented to numerically solve the governing *** effects of various parameters,including the viscosity parameter,ranging from 1 to 3,the thermal conductivity parameter,ranging from 1 to 3,the Rayleigh parameter,ranging from 102 to 3×10^(2),the radiation number,ranging from 0.1 to 0.5,the fusion temperature,ranging from 1.0 to 1.2,the volume fraction of NEPCMs,ranging from 2%to 6%,the stefan number,ranging from 1 to 5,the magnetic number,ranging from 0.1 to 0.5,and the irreversibility parameter,ranging from 0.1 to 0.5,are examined in detail on the temperature contours,isentropic lines,heat capacity ratio,and velocity ***,the heat transfer rates at both the cold and hot walls are analyzed,and the findings are presented *** results indicate that the time taken by the NEPCMs to transition from solid to liquid is prolonged inside the chamber region as the fusion temperatureθf ***,the contours of the heat capacity ratio Cr decrease with the increase in the stefan number ste.

关键词： volume fraction of nano-encapsulated phase change material(NEPCM) radiation stefan number heat capacity ratio entropy generation

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In situ nanoscale mapping of electrical and catalytic properties

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National science Review 2024年第7期11卷 65-66页

作者： Christopher s.Kley helmholtz Young Investigator Group Nanoscale Operando CO2 Photo-Electrocatalysis Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Department of Interface science Fritz Haber Institute of the Max Planck Society

By enabling the conversion of sustainably-derived electrical energy into chemical energy, electrocatalytic reactions are vital for closing the anthropogenic carbon cycle. A wide array of electrocatalytic reactions have gained extensive attention, including hydrogen evolution（hER）, oxygen evolution（OER）, and CO2electroreduction（CO2RR）.

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A new route to weak force sensing beyond sQl:squeezed magnons in cavity magnomechanics

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science China(Physics,Mechanics & Astronomy) 2024年第10期67卷 166-167页

作者： s.K.Özdemir Department of Engineering science and Mechanics and Materials Research Institute(MRI)The Pennsylvania State UniversityUniversity ParkPA 16802USA

Quantum mechanics imposes limits on measurement accuracy through quantum noise which typically has two components:First is the shot noise originating from vacuum fluctuations and referred to as the imprecision *** is ... 详细信息

关键词： quantum typically vacuum

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Mathematical modeling and simulations of stress mitigation by coating polycrystalline particles in lithium-ion batteries

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 947-962页

作者： N.IQBAl J.ChOI s.F.shAh C.lEE s.lEE Department of Mechanical Roboticsand Energy EngineeringDongguk University-SeoulSeoul 04620Republic of Korea

A chemo-mechanical model is developed to investigate the effects on the stress development of the coating of polycrystalline Ni-rich liNixMnyCo_(z)O_(2)(x≥0.8)(NMC)particles with poly(3,4-ethylenedioxythiophene)(PEDOT).The simulation results show that the coating of primary NMC particles significantly reduces the stress generation by efficiently accommodating the volume change associated with the lithium diffusion,and the coating layer plays roles both as a cushion against the volume change and a channel for the lithium transport,promoting the lithium distribution across the secondary particles more ***,the lower stiffness,higher ionic conductivity,and larger thickness of the coating layer improve the stress *** paper provides a mathematical framework for calculating the chemo-mechanical responses of anisotropic electrode materials and fundamental insights into how the coating of NMC active particles mitigates stress levels.

关键词： lithium-ion battery(lIB) polycrystalline particle coating finite element simulation Ni-rich liNixMnyCo_(z)O_(2)(x>0.8)(NMC)

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Improving Generalization for hyperspectral Image Classification: The Impact of Disjoint sampling on Deep Models

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Computers, Materials and Continua 2024年第1期81卷 503-532页

作者： Ahmad M. Mazzara M. Distefano s. Khan A.M. Altuwaijri h.A. Department of Computer science National University of Computer and Emerging Sciences Chiniot 35400 Pakistan Institute of software Development and Engineering Innopolis University Innopolis 420500 Russian Federation Dipartimento di Matematica e Informatica—MIFT University of Messina Messina 98121 Italy school of Computer science University of Hull Hull HU6 7RX United Kingdom Department of Geography College of Humanities and Social Sciences King Saud University Riyadh 11451 Saudi Arabia

Disjoint sampling is critical for rigorous and unbiased evaluation of state-of-the-art (sOTA) models e.g., Attention Graph and Vision Transformer. When training, validation, and test sets overlap or share data, it introduces a bias that inflates performance metrics and prevents accurate assessment of a model’s true ability to generalize to new examples. This paper presents an innovative disjoint sampling approach for training sOTA models for the hyperspectral Image Classification (hsIC). By separating training, validation, and test data without overlap, the proposed method facilitates a fairer evaluation of how well a model can classify pixels it was not exposed to during training or validation. Experiments demonstrate the approach significantly improves a model’s generalization compared to alternatives that include training and validation data in test data (A trivial approach involves testing the model on the entire hyperspectral dataset to generate the ground truth maps. This approach produces higher accuracy but ultimately results in low generalization performance). Disjoint sampling eliminates data leakage between sets and provides reliable metrics for benchmarking progress in hsIC. Disjoint sampling is critical for advancing sOTA models and their real-world application to large-scale land mapping with hyperspectral sensors. Overall, with the disjoint test set, the performance of the deep models achieves 96.36% accuracy on Indian Pines data, 99.73% on Pavia University data, 98.29% on University of houston data, 99.43% on Botswana data, and 99.88% on salinas data. © 2024 The Authors.

关键词： disjoint sampling Graph CNN hyperspectral image classification spatial-spectral transformer

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