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Asteroseismology of the DBV star CBS 114

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Research in Astronomy and Astrophysics 2016年第8期16卷 17-24页

作者： Yan-hui chen Institute of Astrophysics Chuxiong Normal University School of Physics and Electronical Science Chuxiong Normal University Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences

Asteroseismology is a unique and powerful tool to investigate the internal structure of stars. CBS 114 is the sixth known pulsating DBV star. It was observed by Handler, Metcalfe, ＆ Wood at the South African Astronomical Observatory over three weeks in 2001. Then, it was observed by Metcalfe et al. for seven nights （2004 Feb. 19-25） on the 1.8 m telescope at the Bohyunsan Optical Astronomy Observatory and seven nights （2004 Feb. 21-27） on the 2.1 m telescope at the McDonald Observatory. Totally two triplets, four doublets, and five singlets were identified. The frequency splitting values are very different, from 5.2 *** to 11.9 ~tHz, which may reflect differential rotations. We evolve grids of white dwarf models by MESA. Cores, added with He/C envelopes, of those white dwarf models are inserted into WDEC to evolve grids of DBV star models. With those DBV star models, we calculate eigenperiods. Those calculated periods are used to fit observed periods. A best-fitting model is selected. The parameters are T^ff ----- 25 000 K, M, = 0.740 MG and log（MHe/M,） = -4.5. With the relatively large stellar mass, the effective temperature is close to the previous spectroscopic result. In addition, kinetic energy distributions are calculated for the best-fitting model. We find that the observed modes with large frequency splitting values are fitted by the calculated modes with a large amount of kinetic energy distributed in the C/O core. After preliminary analysis, we suggest that the C/O core may rotate at least two times faster than the helium layer for CBS 114.

关键词： stars: oscillations (including pulsations) -- stars: individual (CBS 114) -- white dwarfs

Mechanisms and active substances of targeting lipid peroxidation in ferroptosis regulation

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Food Science and Human Wellness 2024年第5期13卷 2502-2518页

作者： hui chen Lingli chen Wenjun Wang Jiangxi Key Laboratory of Natural Products and Functional Food College of Food Science and EngineeringJiangxi Agricultural UniversityNanchang 330045China

Ferroptosis is a novel form of cell death driven by iron-dependent lipid peroxidation and it is implicated in various diseases,such as liver disease,acute kidney injury,cardiovascular disease,neurodegenerative disease and ***-based reactive oxygen species(ROS),particularly lipid hydroperoxides in the cellular membrane can lead to membrane disruption and cell death mediated by *** are three necessary stages involving in the process of lipid peroxidation regulation in ferroptosis,including the synthesis of membrane phospholipids,initiation of lipid peroxidation and clearance of lipid *** this review,we summarized the molecular modulation mechanisms of lipid peroxidation in ferroptosis from the above three stages,as well as various ferroptosis modulators targeting lipid peroxidation,including commonly used products,natural bioactive compounds and ***,these findings suggest the vital role of lipid peroxidation in ferroptosis,and targeting lipid peroxidation in ferroptosis is potential to treat ferroptosis-associated diseases.

关键词： Ferroptosis Lipid peroxidation Mechanisms Natural bioactive compounds Selenocompounds

基于改进ResNet的多标签胸部X光图像分类

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山东理工大学学报（自然科学版） 2025年第2期39卷 1-9页

作者：方燕燕陈辉安徽理工大学计算机科学与工程学院安徽淮南232001

针对目前胸部X光图像分类方法存在X光特异性特征表达不充分、高频图像特征提取效果差、疾病样本数量不平衡等问题,提出一种基于改进ResNet的多标签胸部X光图像分类方法(multi-label chest X-ray image classification based on improved... 详细信息

针对目前胸部X光图像分类方法存在X光特异性特征表达不充分、高频图像特征提取效果差、疾病样本数量不平衡等问题,提出一种基于改进ResNet的多标签胸部X光图像分类方法(multi-label chest X-ray image classification based on improved ResNet, MLC-ResNet)。首先,设计一个多尺度特征提取和融合模块,以获取更丰富的特征信息;其次,将八度卷积替换为残差结构中的普通卷积,解决X光特异性特征表达不充分问题;再次,为改善高频特征提取效果,在ResNet中引入改进后的多层感知器(multilayer perception, MLP),更好地揭示图像的细节和整体结构,增加分类性能;最后,使用加权交叉熵损失函数增加样本数较少的类别权重,改善样本分布不平衡问题。在ChestX-Ray14和CheXpert数据集上进行实验测试,其平均AUC分别是0.858 7和0.844 7,相较于ResNet分类算法分别提高了4.47%和3.20%。通过与现有方法的对比实验,进一步证明MLC-ResNet模型具有更好的性能。

关键词：多层感知器 ResNet 加权交叉熵损失函数胸部X光图像

Residual stress indentation model based on material equivalence

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Chinese Journal of Aeronautics 2022年第8期35卷 304-313页

作者： Xiaokun LIU Lixun CAI hui chen Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and EngineeringSouthwest Jiaotong UniversityChengdu 610031China School of Civil Engineering Changsha University of Science&TechnologyChangsha 410114China

A novel residual stress indentation model for conical indentation loading is proposed to describe the relationship between the residual stress,material constitutive parameters,load,and displacement for materials with a uniaxial constitutive relationship that obeys Hollomon’s power law(H-law).The novel model was established based on the principle that the equivalent material without residual stress corresponds to the original material with residual stress,conical indentation theoretical model based on energy density equivalence,and an assumed power-law relationship between the dimensionless residual stress and relative difference of the yield stresses of the equivalent material and original *** imaginary H-law materials with ten equibiaxial and ten uniaxial residual stresses were investigated by Finite Element Analysis(FEA).The residual stresses predicted by the novel model from the indentation load–displacement curves simulated for the imaginary materials are in close agreement with those applied by the ***,indentation tests for Cr12Mo V steel,45 steel,and 6061-T6511 aluminum alloy were carried out on their specimens without residual stress and their bending specimens with equibiaxial and uniaxial residual *** residual stresses predicted by the novel model according to the indentation load–displacement test curves are in good agreement with those applied by the tests.

关键词： Conical indentation Equivalent material Finite element analysis Residual stress Theoretical model

Characterization of creep behavior of TiAl alloy with high Nb content at elevated temperatures

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Rare Metals 2016年第1期35卷 106-112页

作者： cheng-Li Dong hui-chen Yu Ze-hui Jiao Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation Science and Technology on Advanced High Temperature Structural Materials LaboratoryBeijing Institute of Aeronautical Materials Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials

Creep experiments of the TiAl alloy with high Nb content were conducted to consider both the temperature dependence and stress dependence of its creep *** creep curves were characterized by Theta constitutive model,and Newton-Gauss method was applied to obtain the material *** on the rupture strain,the rupture life of the TiAl alloy was able to be predicted by Theta constitutive *** results show that the creep curves of the TiAl alloy contain primary creep,secondary creep and tertiary creep stages,especially for the lower *** rupture life of the TiAl alloy decreases with the increase in either applied stress or *** constitutive model is able to describe the creep deformation of the TiAl alloy accurately,and the predicted life agrees well with the experimental result.

关键词： TiAl alloy Creep Rupture Life prediction Theta constitutive model

SURFACE EFFECT ON NANOSIZED VOID GROWTH IN A RIGID-PERFECTLY PLASTIC MATERIAL

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Acta Mechanica Solida Sinica 2008年第1期21卷 9-14页

作者： Tong hui Yiheng chen School of Aerospace MOE Xi＇an Jiaotong University Xi＇an 710049 China

The influence of the surface effect on the nanosized spherical void growth in a rigidperfectly plastic material is analyzed and the mechanism of the nanosized void growth with high triaxiality is given. Based on the Rice and Tracey model for a macro void growth, the present model is proposed to account for the nanosized void growth under a uniform remote strain rate field with consideration on the surface effect. It is concluded that the surface effect yields an evident resistant influence on the nanosized void growth. That is, this influence decays as the void radius increases. With high triaxiality, the nanosized void growth is divided into two stages： the initial stage and the mature stage. At the first stage, the void grows slowly and the influence of surface effect is relatively weak, whereas at the second stage, the influence is significant and the void grows drastically.

关键词： nanosized void extended variational principle void growth surface effect high triaxiality

Theoretical methods for excited state dynamics of molecules and molecular aggregates

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Science China Chemistry 2013年第9期56卷 1271-1276页

作者： SHI Qiang chen hui Beijing National Laboratory for Molecular Science (BNLMS) Institute of ChemistryChinese Academy of Sciences

This contribution provides a summary of proposed theoretical and computational studies on excited state dynamics in molecular aggregates, as an important part of the National Natural Science Foundation (NNSF) Major Project entitled "Theoretical study of the low-lying electronic excited state for molecular aggregates". This study will focus on developments of novel methods to simulate excited state dynamics of molecular aggregates, with the aim of understanding several important chemical physics processes, and providing a solid foundation for predicting the opto-electronic properties of organic functional materials and devices. The contents of this study include: (1) The quantum chemical methods for electronic excited state and electronic couplings targeted for dynamics in molecular aggregates; (2) Methods to construct effective Hamiltonian models, and to solve their dynamics using system-bath approaches; (3) Non-adiabatic mixed quantum-classic methods targeted for molecular aggregates; (4) Theoretical studies of charge and energy transfer, and related spectroscopic phenomena in molecular aggregates.

关键词： excited state dynamics molecular aggregates effective Hamiltonian models mixed quantum-classical dynamics

Optimization of the S-band side-coupled cavities for proton acceleration

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Nuclear Science and Techniques 2020年第3期31卷 1-9页

作者： Hao-Yun Li Xin-Miao Wan Wei chen chen-hui Shi Zhi-hui Li The Key Laboratory of Radiation Physics and Technology of Ministry of Education Institute of Nuclear Science and Technology Sichuan University

The proton beam with energy around 100 MeV has seen wide applications in modern scientific research and in various ***,proton sources in China fall short for meeting experimental needs owing to the vast size and expensive traditional proton *** Institute of Nuclear Science and Technology of Sichuan University proposed to build a 3 GHz side-coupled cavity linac(SCL)for re-accelerating a 26 MeV proton beam extracted from a CS-30 cyclotron to 120 *** carried out investigations into several vital factors of S-band SCL for proton acceleration,such as optimization of SCL cavity geometry,end cell tuning,and bridge coupler *** demonstrated that the effective shunt impedance per unit length ranged from 22.5 to 59.8 MX/m throughout the acceleration process,and the acceleration gradient changed from 11.5 to 15.7 MV/m when the maximum surface electric field was equivalent to Kilpatrick electric *** obtained equivalent circuit parameters of the biperiodic structures and applied them to the end cell tuning;results of the theoretical analysis agreed well with the 3D *** designed and optimized a bridge coupler based on the previously obtained biperiodic structure parameters,and the field distribution un-uniformness was\1.5%for a two-tank *** radio frequency power distribution system of the linac was obtained based on the preliminary beam dynamics design.

关键词： Proton beam Side-coupled cavity linac Accelerating cavity Biperiodic structure Bridge coupler

Approximation for Counts of 2-runs in a Two State Markov Chain

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Acta Mathematica Sinica,English Series 2013年第10期29卷 1907-1916页

作者： hui chen Mei ZHANG School of Mathematical Sciences Beijing Normal University

We consider a Markov chain X = {Xi, i = 1, 2,...} with the state space {0, 1}, and define W = ∑1=1^x XiXi＋1, which is the number of 2-runs in X before time n ＋ 1. In this paper, we prove that the negative binomial distribution is an appropriate approximation for LW when VarW is greater than EW. The error estimate obtained herein improves the corresponding result in previous literatures.

关键词： Negative binomial distribution head run Stein's method total variation distance cou-pling