作者机构:
[Lin-Qing Gao] School of Nuclear Science and Technology, University of South China, Hengyang 421001, China;[Peng-Fei Yin] Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China;School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China;[Jun-Guang Guo] School of Physics and Electronic Engineering, Jiaying University, Meizhou 514015, China;[Wenbin Lin] School of Mathematics and Physics, University of South China, Hengyang 421001, China
摘要:
Axionlike particles (ALPs) may undergo mixing with photons in the presence of astrophysical magnetic fields, leading to alterations in the observed high energy γ -ray spectra. In this study, we investigate the ALP-photon oscillation effect using the spectra of the blazar Mrk 421 over 15 observation periods measured by Major Atmospheric Gamma Imaging Cherenkov Telescopes (MAGIC) and Fermi Large Area Telescope (Fermi-LAT). Compared with previous studies, we generate mock data under the ALP hypothesis and employ the CLs method to set constraints on the ALP parameters. This method is widely utilized in high energy experiments and avoids the exclusion of specific parameter regions where distinguishing between the null and ALP hypotheses is challenging. We find that the ALP-photon coupling gaγ is constrained to be smaller than ∼2×10−11 GeV−1 for ALP masses ranging from 10−9 eV to 10−7 eV at the 95% confidence level. We also present the constraints derived from the TS distribution under the null hypothesis, which is commonly utilized in previous astrophysical ALP studies. Our results reveal that the combined constraints of all the periods obtained from both methods are consistent. However, the CLs method remains effective in cases where the latter method fails to provide constraints for specific observation periods.
作者机构:
[Lin, Wenbin; Yang, Bo] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Lin, Wenbin] Southwest Jiaotong Univ, Sch Phys Sci & Technol, Chengdu 610031, Peoples R China.;[Li, Jie] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.
通讯机构:
[Wenbin Lin] S;School of Mathematics and Physics, University of South China, Hengyang, China<&wdkj&>School of Physical Science and Technology, Southwest Jiaotong University, Chengdu, China
期刊:
Physics of the Dark Universe,2023年42:101308 ISSN:2212-6864
通讯作者:
Lin, WB
作者机构:
[Li, Jie] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Lin, Wenbin; Yang, Bo; Lin, WB] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Wang, Yu] Univ Rome, Dip Fis, ICRA, Ple Aldo Moro 5, I-00185 Rome, Italy.;[Lin, Wenbin] Southwest Jiaotong Univ, Sch Phys Sci & Technol, Chengdu 610031, Peoples R China.
通讯机构:
[Lin, WB ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词:
Quark stars;Massive gravity;MIT bag model;Tolman-Oppenheimer-Volkoff equation
摘要:
We investigate the structure of quark stars in de Rham-Gabadadze-Tolley like massive gravity with an anisotropic matter source. The MIT bag model as the equation of state for compact stars is used to numerically solve the modified Tolman-Oppenheimer-Volkoff equation. We analyze the effects of bag constant, anisotropy parameter and massive gravity parameters on the structure of quark stars. The results show that the mass and radius of the quark star depend on these parameters significantly, and the maximum mass can satisfy the observational data for the massive pulsar PSR J0348+0432. Furthermore, we also discuss other properties of quark stars, including dynamical stability, Schwarzschild radius and compactness.& COPY; 2023 Elsevier B.V. All rights reserved.
摘要:
In 5G frequency division duplex (FDD) systems, the user equipment needs to feedback the measured downlink channel state information (CSI) to the base station to improve the throughput. For massive multiple-input-multiple-output (MIMO) systems, each antenna in base station needs its CSI feedback, which results in significant transmission overhead and latency. We propose an attention-based deep learning network to directly predict the downlink CSI from the corresponding uplink one, eliminating the feedback overhead completely. Specifically, the uplink CSI is first compressed based on the 3D inverse discrete Fourier transform, then is fed into an attention-based deep learning network which can focus on key CSI characteristics. The simulation results show that the proposed method achieves high prediction accuracy and low complexity, indicating prospective applications in FDD massive MIMO systems.
期刊:
Measurement Science And Technology,2023年34(6) ISSN:0957-0233
作者机构:
[Xie, Shuibo; Liao, Yanguo] Univ South China, Sch Resource Environm & Safety Engn, Hengyang 421001, Peoples R China.;[Liao, Yanguo] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Xie, Shuibo] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.
关键词:
transversely isotropic materials;cylindrical indentation;elastic parameters;dimensional analysis;finite element (FE);three-dimensional (3D)
摘要:
Based on the cylindrical indention experiments, a novel model has been established to characterize the elastic mechanical property of transversely isotropic materials. In the first place, the influences of different loading orientations for indentation, and elastic parameters of materials on the indentation modulus of transversely isotropic materials are analyzed by means of theoretical and dimensional analysis. In the second place, three dimensional (3D) indentation experiments that encompass the wide range of transversely isotropic material parameters are simulated by finite element (FE) approach. Each quantity (transversely isotropic Young's modulus, EP, longitudinal Young's modulus, EL, longitudinal shear modulus, GL, and loading orientation angle, ) how affects the normalized indentation modulus is investigated. Then, the dimensionless analytical relationship between indentation modulus and elastic parameters is put up at three different indentation orientation angles . To prove the correctness of the proposed model, several groups of transversely isotropic materials are selected as input parameters to carry out indentation numerical experiments and the error analysis is made in detail. Simultaneously, the technique is specialized to the particular case of a Zinc single crystal material to verify the accuracy of these formulas derived. These good agreements show that the proposed method is reliable and it could be used to quantify the elastic parameters of the transversely isotropic materials.
通讯机构:
[Zhou, MH; Ren, Z ] C;Chinese Acad Sci, Beijing Natl Lab Condensed Matter Phys, Inst Phys, Beijing 100190, Peoples R China.;Univ Chinese Acad Sci, Sch Phys Sci, Beijing 100049, Peoples R China.
摘要:
We report the crystal and electronic structures, charge density wave (CDW), and superconductivity of polycrystalline 4Ha-NbSe2 studied by x-ray diffraction, ab initio calculations, electrical resistivity, magnetization, and specific heat. 4Ha-NbSe2 has no central inversion symmetry (space group P-6m2), and the stacking-fault structure was observed in the crystal lattice. The weak CDW transition at TCDW -43 K thermodynamically is of second order. 4Ha-NbSe2 has a superconducting critical temperature Tc -6.4 K, which is a moderately coupled BCS superconductor with two-gap s +s-wave-like pairing. The upper critical field mu 0Hc2(0) is as high as 26.5 T which far exceeds the Pauli paramagnetic limit and this violation is mostly attributed to the breaking of the central inversion symmetry. Second magnetization peaks can be observed in the system with weak flux pinning. Electronic structure calculations reveal that the Nb 4d orbitals dominate the bands near the Fermi level with different degree of hybridization between the Nb 4d and Se 4p orbitals in 2H- and 4Ha-NbSe2, and the band structures of 4Ha-NbSe2 favor a higher TCDW. The higher TCDW but lower Tc compared to 2H-NbSe2 leads us to conclude that the two collective electronic states are competitive on the Fermi surface in this system. The large mu 0Hc2(0) derived from 4Ha-NbSe2 is expected to stimulate the explorations for high-field superconductor applications from a noncentrosymmetric structural strategy.
摘要:
In the present work, based on Wentzel-Kramers-Brillouin theory, we systematically study the cluster
radioactivity half-lives of 22 nuclei ranging from 221Fr to 242Cm by using a phenomenological model, which considers
the screened electrostatic effect of Coulomb potential. In this model, there are two adjustable parameters i.e. the
parameter t and g, which are related to the screened electrostatic barrier and the strength of spectroscopic factor,
respectively. The calculated results indicate this model can well reproduce the experimental data while the corre sponding root-mean-square (rms) deviation is 0.660. In addition, we extend this model to predict the half-lives of
possible cluster radioactive candidates whose cluster radioactivity are energetically allowed or observed but not
yet quantified in the evaluated nuclear properties table NUBASE2020. The predicted results are consistent with
the ones obtained by using other theoretical models and/or empirical formulae including the universal decay law
(UDL) proposed by Qi et al. [Phys. Rev. C 80, 044326 (2009)], a semi-empirical model for both α decay and cluster
radioactivity proposed by Santhosh et al. [J. Phys. G 35, 085102 (2008)] and a unified formula of half-lives for α
decay and cluster radioactivity proposed by Ni et al. [Phys. Rev. C 78, 044310 (2008)].
摘要:
In the present work, the cluster radioactivity preformation probability Pc in the scheme of NpNn for the effective number of the valence particles (holes) in trans-lead nuclei has been systematically investigated. This quantity has been explored in the simplified parametrization of NpNn as well as the multiplication NpNnI of this product with the isospin asymmetry I. The calculations for Pc are both performed in microscopic and model-dependent way. Within the microscopic approach, based on our previous work [Chin. Phys. C 47, 014101 (2023)], Pc is calculated in cluster formation model combined with the exponential relationship of Pc to the & alpha; decay preformation probability P & alpha; when the mass number of the emitted cluster Ac 28. While Ac 28, Pc is obtained through the charge-number dependence of Pc on the decay products proposed by Ren et al. [Phys. Rev. C 70, 034304 (2004)]. In the model-dependent approach, Pc is extracted through the ratios from calculated cluster radioactivity half-lives in the framework of unified fission model proposed by Dong et al. [Eur. Phys. J. A 41, 197 (2009)] to experimental ones. Both of the results show Pc in logarithmic form are linear to NpNn as well as NpNnI. For comparison, the parent-mass-number dependence analytical formula as well as the model proposed by Wei and Zhang [Phys. Rev. C 96, 021601(R) (2017)] are also used. Furthermore, the preformation mechanic for cluster radioactivity has also been discussed.
摘要:
通用视频编码(versatile video coding,VVC)标准由联合视频专家组共同制定,它遵循基于混合块的编解码器及其前身高效视频编码(high efficient video coding,HEVC)的传统架...展开更多 通用视频编码(versatile video coding,VVC)标准由联合视频专家组共同制定,它遵循基于混合块的编解码器及其前身高效视频编码(high efficient video coding,HEVC)的传统架构。与HEVC相比,VVC的帧内预测功能包含大量修改,编码效率大大提高。在VVC的基础上,提出了一种改进的基于亮度残差的帧内编码算法,通过减少率失真代价的检查次数,在保证编码质量不受较大影响的前提下,降低了计算复杂性,并提高了VVC的帧内编码效率。实验结果表明,在VTM16.0的VVC软件版本下,在相同配置下,改进算法的编码时间可以减少27.03%,而Bj?ntegaard-Delta rate只增加了0.9%。收起
摘要:
In this paper, the speed selection for the time periodic traveling wave solutions of a two-species competition lattice model of diffusive Lotka-Volterra type is investigated. By using the upper-lower solution method, an abstract result and several explicit sufficient conditions for linear selection are established. Moreover, a general condition for nonlinear selection is also obtained, which indicates that the minimal speed is nonlinearly selected if the system admits a lower solution with faster decay at the far end. Based on this result, some explicit conditions for nonlinear selection are found by constructing novel lower solutions.(c) 2022 Elsevier Inc. All rights reserved.
摘要:
The commercial exploitation of the deep-sea massive deep-sea polymetallic nodules depends on the excellent tractive performance of the deep-sea tracked miner. The walking safety and trafficability of the deep-sea tracked miner are greatly influenced by the traction of the crawler with multi track shoes. The total tractions generated from the two cases of failure surface under the uniformed pressure are deduced and analyzed based on the principle of virtual power. By substituting specified parameters, the traction weakening effect of multi track shoes is discovered, and then corresponding expression is put forward and verified by comparing the tested and theoretical traction relationships based on the traction test of multi track shoes. The research results show that the height and the distance should be considered into the design in a comprehensive way because of the existence of the weakening effect. The mechanism revealing of the source of the multi track shoe tractions could help to achieve the appropriate size of the track shoe and more traction according to the different track shoe distance.
期刊:
Journal of Radioanalytical and Nuclear Chemistry,2023年332(2):251-259 ISSN:0236-5731
通讯作者:
Zhenghua Xu<&wdkj&>Yong Liu
作者机构:
[Yifan Chen; Xianwei Wu; Xingwang Dai] School of Resources Environmental and Safety Engineering, University of South China, Hengyang, China;[Tiejun Zhang] China Nuclear Industry 23 Construction Co., LTD., Beijing, China;[Min Zhang] China Nuclear Huachen Construction Engineering Co., LTD., Xi’an, China;[Zhenghua Xu] School of Mathematics and Physics, University of South China, Hengyang, China;[Yong Liu] College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
通讯机构:
[Zhenghua Xu] S;[Yong Liu] C;School of Mathematics and Physics, University of South China, Hengyang, China<&wdkj&>College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
关键词:
Radon;Stable zone;WOA-BP;Early warning
摘要:
Radon is a radioactive gas produced by the decay of radium in uranium tailings, which can migrate to the atmosphere through tiny pores in the soil and can be used to characterize the internal stability of tailings dam. A method for determining the stable zone of radon is proposed, in which the radon concentration of uranium tailings pond is divided into stable zone, asymptotically stable zone, and unstable zone, and through the WOA-BP neural network algorithm for intelligent early warning of stability zone. The results show that the MAPE (Mean Absolute Percentage Error) is reduced by 20.16% by dividing the stable region, And MAPE of WOA-BP neural network algorithm is 8.22% lower than that of BP neural network algorithm. It shows that this method can provide guidance for the safe and stable operation of uranium tailings pond.