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Bulk viscosity of interacting magnetized strange quark matter

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Nuclear Science and Techniques 2021年第10期32卷 101-109页

作者： Jian-feng xu School of Physics and Electrical Engineering AnYang Normal UniversityAnyang 455000China

The bulk viscosity of interacting strange quark matter in a strong external magnetic field B m with a real equation of state is *** is found that interquark interactions can significantly increase the bulk viscosity,and the magnetic field B_(m) can cause irregular oscillations in both components of the bulk viscosity,ξ||(parallel to B_(m))and ξ⊥(perpendicular to B_(m)).A comparison with non-interacting strange quark matter reveals that when B_(m) is sufficiently large,ξ⊥is more affected by interactions than ξ||.Additionally,the quasi-oscillation of the bulk viscosity with changes in density may facilitate the for-mation of magnetic ***,the resulting r-mode instability windows are in good agreement with observational data for compact stars in low-mass X-ray ***,the r-mode instability window for interacting strange quark matter in high magnetic fields has a minimum rotation frequency exceeding 1050 Hz,which may explain the observed very high spin frequency of a pulsar with V=1122 Hz.

关键词： Strange quark matter Bulk viscosity Strong magnetic field Strange star R-mode instability window

基于轻量化卷积神经网络的桥梁斜拉索PE护套损伤识别方法

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土木与环境工程学报（中英文） 2025年第1期47卷 167-178页

作者：刘啸宇黄永徐峰李惠上海交通大学船舶海洋与建筑工程学院上海200240 哈尔滨工业大学土木工程学院哈尔滨150090

深度神经网络和计算机视觉技术近年来在结构健康监测中发挥了越来越重要的作用。利用无人机航拍采集的桥梁斜拉索损伤图像数据,研究基于深度学习技术的斜拉索PE护套损伤识别方法。为实现在较低运算能力设备上对大跨度桥梁斜拉索表面局... 详细信息

深度神经网络和计算机视觉技术近年来在结构健康监测中发挥了越来越重要的作用。利用无人机航拍采集的桥梁斜拉索损伤图像数据,研究基于深度学习技术的斜拉索PE护套损伤识别方法。为实现在较低运算能力设备上对大跨度桥梁斜拉索表面局部损伤的智能快速识别,解决传统深度卷积神经网络的运算效率相对较低、模型参数规模较大的问题,提出轻量化处理的区域推荐型卷积神经网络模型。介绍区域推荐网络与其轻量化改进方法的理论基础,分析轻量化模型处理的必要性,其能在保证识别精度的前提下降低模型训练与预测的设备性能需求,达到节约计算资源与时间的目的;通过数据增广等多手段解决损伤样本数据量不足的问题,设置对比试验,统计分析结果,验证了轻量化神经网络模型的优越性。结果表明,轻量化网络在牺牲少量识别准确度的前提下,能够在较大程度上实现对模型复杂度与计算量的改进,在工程应用中能有效拓展神经网络的实用性。

关键词：桥梁斜拉索智能损伤识别轻量化神经网络计算机视觉深度学习

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A modular multilevel power flow controller for meshed HVDC grids

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Science China(Technological Sciences) 2014年第9期57卷 1773-1784页

作者： xu feng xu Zheng Department of Electrical Engineering Zhejiang University

Based on the comparison of existing power flow controllers(PFC)in meshed HVDC grids,the full-bridge modular multilevel converter based PFC(MMPFC)is *** first,the general branch current calculation method of meshed HVDC grids with the PFC is presented,and then,the issue of over-voltage on the thyristor based PFC is described and *** the analysis of different operating modes of the full-bridge sub-module,the mechanism of over-voltage ride through of the MMPFC is *** control strategy of the MMPFC,which is used to control branch current and keep capacitor voltage balancing,is ***,the performance on current regulation,bidirectional operation and over-voltage ride through is simulated and verified in a built model with PSCAD/EMTDC.

关键词： meshed HVDC grids multi-terminal HVDC modular multilevel power flow controller (MMPFC) bidirectional operation over-voltage ride through full-bridge sub-module

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Cu-Fe合金凝固过程中结构变化研究

原子与分子物理学报 2025年第6期42卷 183-192页

作者：王旭锋张真豪高绪锋金雅璇张寒雨李运刚华北理工大学冶金与能源学院唐山063210

采用分子动力学模拟方法研究了Cu_(100-X)Fe_(X)(X=1%、3%、5%)合金在冷却速率为2×10^(10)K/s条件下合金凝固过程.研究表明,Fe含量为1%时,随着合金温度的降低Fe原子始终保持均匀分布的状态,未出现Fe原子聚集现象,晶体结构是以FCC为主... 详细信息

采用分子动力学模拟方法研究了Cu_(100-X)Fe_(X)(X=1%、3%、5%)合金在冷却速率为2×10^(10)K/s条件下合金凝固过程.研究表明,Fe含量为1%时,随着合金温度的降低Fe原子始终保持均匀分布的状态,未出现Fe原子聚集现象,晶体结构是以FCC为主的Cu基体,Fe原子以固溶形式存在于基体中.Fe含量为3%时,随着合金温度的降低Fe原子有聚集趋势,但BCC晶体结构占比较小,晶体结构仍是以FCC为主的Cu基体.Fe含量为5%,随着合金温度的降低Fe原子发生明显聚集,最终形成以FCC、HCP晶体类型为主镶嵌Fe原子的Cu基体.研究了Fe团簇的形成过程,结果表明,Fe团簇的形成、长大是一个连续的过程,该过程受形核生长机制控制,不同阶段形成Fe团簇的大小和数量受Fe-Fe原子相互作用力、Fe原子的扩散能力以及Fe团簇与Cu基体间的界面能三个因素共同影响.

关键词： Cu-Fe合金快速凝固晶体结构 Fe团簇

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A Mean Value of Cochrane Sum

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Acta Mathematica Sinica,English Series 2009年第2期25卷 223-234页

作者： Zhe feng xu College of Science Xi'an Jiaotong University Xi'an 710049 P. R. China Department of Mathematics Northwest University Xi'an 710069 P. R. China

Let q 〉 4 be an integer. The main purpose of this paper is to study the mean value of Cochrane sum C（a, q） in quarter intervals, and obtain a sharp asymptotic formula for it.

关键词： Dedekind sum Cochrane sums mean value asymptotic formula

Unconventional chiral d-wave superconducting state in strained graphene

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Chinese Physics B 2019年第11期28卷 326-332页

作者： feng xu Lei Zhang Department of Physics Jiangxi Normal UniversityNanchang 330022China Department of Physics Shaanxi University of TechnologyHanzhong 723001China

We consider a highly unconventional superconducting state with chiral d-wave symmetry in doped graphene under strain with the Gutzwiller–RVB method in the momentum space. It is shown that flat bands emerge in the normal state for reasonable strain. As a result, the superconducting critical temperature is found to be linearly proportional to the strength of the electron–electron interaction. Furthermore, the chiral d-wave superconducting state is shown with coexistence of the charge density wave and the pair density wave. There are different coexisting states with those orders under different doping levels.

关键词： chiral d-wave superconducting state pair density wave flat band doped graphene

Experimental research on grouser traction of deep-sea mining machine

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Applied Mathematics and Mechanics(English Edition) 2015年第9期36卷 1243-1252页

作者： Wenbo MA Qiuhua RAO Kang feng feng xu School of Civil Engineering Central South University

The traction characteristics of the grouser, cutting the simulative soil of deepsea sediment, with different tooth widths, tooth heights, and ground pressures are studied with traction characteristic test apparatus. A traction-displacement model is obtained by combining the analysis of the cutting mechanism. The results show that the tractiondisplacement curves of grousers with different tooth widths, tooth heights, and ground pressures have the same changing trend, which matches the Wong traction model. Their sensitivity coefficient and shear modulus are slightly fluctuated. Therefore, the average values can be used as the traction model parameters. The maximum traction of the grouser with a two-side edge and a 10 mm tooth width increment changing with the tooth height and ground pressure can be determined according to the grousers with different tooth widths. By combining the traction model parameters, the traction-displacement curve of the grouser with a certain group values of tooth width, tooth height, and ground pressure can be predicted. Therefore, the slip of the mining machine can be prevented to improve the mining efficiency.

关键词： deep-sea sediment simulative soil traction test deep-sea mining machine,grouser traction model

Refined empirical line method to calibrate IKONOS imagery

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第4期7卷 641-646页

作者： xu Jun-feng HUANG Jing-feng Institute of Agricultural Remote Sensing and lnformation Technology Zhejiang University Hangzhou 310029. China

To extract quantitative biophysical parameters such as leaf biomass and leaf chlorophyll concentration from the remotely sensed imagery, the effect of atmospheric attenuation must be removed. The refined empirical line （REL） method was used to calibrate the IKONOS multispectral imagery. The IKONOS digital numbers （DN） were converted to the at-satellite reflectance, then the linear relation between at-satellite reflectance and surface spectral reflectance （ρA） was derived from six bright targets of known reflectance in the image, and modelled estimates of the image reflectance at ρA=0. Validation targets were used to test the feasibility of REL method. The mean relative errors between ρA retrieved from IKONOS image using REL method and ground-measured ρA were 11%, 13%, 3% and 5% in the IKONOS blue, green, red and near-infrared （NIR） respectively. When dark targets are unavailable or measurement of dark target is inconvenient, the REL method was most crucial for retrieving surface spectral reflectance. The REL offers a simple approach for quantitative retrieval of biophysical parameters from IKONOS imagery.

关键词： Calibration Refined empirical line (REL) method IKONOS

On the Mean Value of the Complete Trigonometric Sums with Dirichlet Characters

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Acta Mathematica Sinica,English Series 2007年第7期23卷 1341-1344页

作者： Zhe feng xu Department of Mathematics Northwest University

The main purpose of this paper is, using the analytic method, to study the mean value properties of the complete trigonometric sums with Dirichlet characters, and give an exact calculating formula for its fourth power... 详细信息

关键词： complete trigonometric sums Dirichlet character mean value