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基于脑-小脑连接梯度的AD患者脑功能层级结构变化研究

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磁共振成像 2024年第5期15卷 1-7页

作者：何美荣莫贤游晚芳孙昂张俊然四川大学电气工程学院成都610065 西北民族大学电气工程学院兰州730030

目的采用基于梯度的方法分析阿尔茨海默病(Alzheimer’s disease,AD)大脑皮层组织沿脑-小脑连接梯度的功能层级结构及其与小脑相互作用的改变,以及与认知功能障碍之间的联系。材料与方法基于AD神经影像学计划(Alzheimer’s Disease Neur... 详细信息

目的采用基于梯度的方法分析阿尔茨海默病(Alzheimer’s disease,AD)大脑皮层组织沿脑-小脑连接梯度的功能层级结构及其与小脑相互作用的改变,以及与认知功能障碍之间的联系。材料与方法基于AD神经影像学计划(Alzheimer’s Disease Neuroimaging Initiative,ADNI)公开数据库,共纳入33名AD患者和46名年龄、性别相匹配的健康对照(healthy controls,HC)。采用梯度计算方法,通过对所有被试的脑-小脑静息态功能连接矩阵进行非线性分解,得到了每个被试的脑-小脑功能连接梯度。采用双样本t检验进行组间的脑-小脑梯度分数差异分析,以及梯度异常的脑区与小脑功能连接的组间比较,并采用相关分析评估了异常的梯度分数以及功能连接值与临床量表分数的相关性。结果与HC组相比,AD组在涉及高级认知功能区域右侧颞下回(right inferior temporal gyrus,RITG)(t=4.71,Pb区(右侧:t=-4.89,Pb脑区的功能连接降低可能是认知功能受损的潜在因素之一。

关键词：阿尔茨海默病脑-小脑连接梯度静息态功能连接磁共振成像功能层级结构

Seismic fragility analysis of highway bridges considering multi-dimensional performance limit state

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Earthquake Engineering and Engineering Vibration 2012年第2期11卷 185-193页

作者： Wang, Qi'ang Wu, ziyan Liu, Shukui School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi'an 710129 China School of Mechanics Civil Engineering and Architecture Chang'an Campus of Northwestern Polytechnical University 883# mailbox Xi'an 710129 China

Fragility analysis for highway bridges has become increasingly important in the risk assessment of highway transportation networks exposed to seismic hazards. This study introduces a methodology to calculate fragility that considers multi-dimensional performance limit state parameters and makes a first attempt to develop fragility curves for a multi-span continuous (MSC) concrete girder bridge considering two performance limit state parameters: column ductility and transverse deformation in the abutments. The main purpose of this paper is to show that the performance limit states, which are compared with the seismic response parameters in the calculation of fragility, should be properly modeled as randomly interdependent variables instead of deterministic quantities. The sensitivity of fragility curves is also investigated when the dependency between the limit states is different. The results indicate that the proposed method can be used to describe the vulnerable behavior of bridges which are sensitive to multiple response parameters and that the fragility information generated by this method will be more reliable and likely to be implemented into transportation network loss estimation.

关键词： highway bridge seismic hazard multi-dimensional performance limit state fragility curves sensitivity

Kinetic Parameters Estimation of MgO-C Refractory by Shrinking Core Model

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Journal of Materials Science & Technology 2006年第6期22卷 826-832页

作者： b.Hashemi z.A.Nemati S.K.Sadrnezhaad z.A.Moghimi Department of Materials Science School of EngineeringShiraz UniversityShirazIran Department of Materials Science and Engineering Sharif University of TechnologyTehran 11365-9466Iran

Kinetics of oxidation of MgO-C refractories was investigated by shrinking core modeling of the gas-solid reactions taking place during heating the porous materials to the high temperatures. Samples containing 4.5-17 wt pct graphite were isothermally oxidized at 1000-1350℃. Weight loss data was compared with predictions of the model. A mixed 2-stage mechanism comprised of pore diffusion plus boundary layer gas transfer was shown to generally control the oxidation rate. Pore diffusion was however more effective, especially at graphite contents lower than 10 wt pct under forced convection blowing of the air. Model calculations showed that effective gas diffusion coefficients were in the range of 0.08 to 0.55 cm^2/s. These values can be utilized to determine the corresponding tortuosity factors of 6.85 to 2.22. Activation energies related to the pore diffusion mechanism appeared to be around （46.44±2） kJ/mol. The estimated intermolecular diffusion coefficients were shown to be independent of the graphite content, when the percentage of the graphite exceeded a marginal value of 10.

关键词： Modeling Kinetics MgO-C Oxidation Diffusion coefficient

Electronic properties and interfacial coupling in Pb islands on single-crystalline graphene

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Chinese Physics b 2022年第3期31卷 517-520页

作者： Jing-Peng Song ang Li State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050China University of Chinese Academy of Sciences Beijing 100049 China

Introducing metal thin films on two-dimensional(2D) material may present a system to possess exotic properties due to reduced dimensionality and interfacial effects. We deposit Pb islands on single-crystalline graphene on a Ge(110)substrate and studied the nano-and atomic-scale structures and low-energy electronic excitations with scanning tunneling microscopy/spectroscopy(STM/STS). Robust quantum well states(QWSs) are observed in Pb(111) islands and their oscillation with film thickness reveals the isolation of free electrons in Pb from the graphene substrate. The spectroscopic characteristics of QWSs are consistent with the band structure of a free-standing Pb(111) film. The weak interface coupling is further evidenced by the absence of superconductivity in graphene in close proximity to the superconducting Pb ***, the Pb(111) islands on graphene/Ge(110) are free-standing in nature, showing very weak electronic coupling to the substrate.

关键词： scanning tunneling microscopy graphene quantum well states superconducting proximity effect

Precise Rates in the Law of the Logarithm for the Moment Convergence in Hilbert Spaces

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Acta Mathematica Sinica,English Series 2009年第2期25卷 191-208页

作者： Ke ang FU Li Xin zHang Department of Mathematics Zhejiang University Hangzhou 310027 P. R. China School of Statistics and Mathematics Zhejiang Gongshang University Hangzhou 310035 P. R. China

Let （X, Xn; n ≥1） be a sequence of i.i.d, random variables taking values in a real separable Hilbert space （H, ｜｜·｜｜） with covariance operator ∑. Set Sn = X1 ＋ X2 ＋ ... ＋ Xn, n≥ 1. We prove that, for b 〉 -1, lim ε→0 ε^2（b＋1） ∞ ∑n=1 （logn）^b/n^3/2 E{｜｜Sn｜｜-σε√nlogn}=σ^-2（b＋1）/（2b＋3）（b＋1） b｜｜Y｜^2b＋3holds if EX=0,and E｜｜X｜｜^2（log｜｜x｜｜）^3bv（b＋4）〈∞ where Y is a Gaussian random variable taking value in a real separable Hilbert space with mean zero and covariance operator ∑, and σ^2 denotes the largest eigenvalue of ∑.

关键词： the law of the logarithm moment convergence tail probability strong approximation

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机场附近频繁变换场景下的6D飞行轨迹预测

高师理科学刊 2024年第3期44卷 43-50页

作者：陈昂李敬有李大辉齐齐哈尔大学计算机与控制工程学院黑龙江齐齐哈尔161006

日益增多的航空活动对航空交通管制提出了挑战,轨迹预测技术在保障空中交通的安全和有序中发挥着重要作用.机场附近更加密集的航班给轨迹预测带来了困难.基于广播式自动相关监视系统,提出了一种基于卷积注意力(Attention-CNNs)的双向长... 详细信息

日益增多的航空活动对航空交通管制提出了挑战,轨迹预测技术在保障空中交通的安全和有序中发挥着重要作用.机场附近更加密集的航班给轨迹预测带来了困难.基于广播式自动相关监视系统,提出了一种基于卷积注意力(Attention-CNNs)的双向长短时记忆网络(biLSTM)和极端梯度提升(XGboost)的混合神经网络模型,能够对飞行轨迹的6D信息(时间、经度、纬度、高度、速度、航向角)进行预测.由包含空间位置和时间戳的时空信息和飞行动态信息组成的轨迹集用于证明该方法的效率.定量分析表明,所提出的模型在评价指标上的表现优于对比模型,为机场环境下航空管理系统的安全运行提供了有效方法.

关键词：航空交通管理轨迹预测卷积神经网络双向长短时记忆网络注意力机制

The xanthate route to all-carbon quaternary centers

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Science China Chemistry 2019年第11期62卷 1450-1462页

作者： béatrice Quiclet-Sire Samir z.zard Laboratoire de Synthèse Organique Ecole Polytechnique

This review discusses the numerous routes to all-carbon quaternary centers based on the unique radical chemistry of xanthates. Itsummarizes the various approaches to the synthesis of tertiary xanthates then describes the intra- and intermolecular radicaladditions and combinations thereof that have so far been used to construct quaternary centers.

关键词： xanthates quaternary centers radical addition cyclization tandem reactions

面向海工结构阴极防护用纳米水泥基热电复合材料制备及其温差自供能性

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复合材料学报 2024年第5期41卷 2662-2673页

作者：袁士柯罗健林高乙博滕飞张纪刚刘昂张立卿青岛理工大学土木工程学院青岛266520 海洋混凝土教育部工程研究中心青岛266520 华东交通大学土木工程学院南昌330013

经略海洋及双碳背景下,用阴极防护(CP)技术提升海工结构服役寿命具有重要意义,然而需外加电源额外驱动。为此本文先用水热法合成纳米二氧化锰(nMnO_(2)),然后与碳纳米管(CNTs)复掺水泥砂浆体系中,制备纳米水泥基热电复合材料(NTEC);最后... 详细信息

经略海洋及双碳背景下,用阴极防护(CP)技术提升海工结构服役寿命具有重要意义,然而需外加电源额外驱动。为此本文先用水热法合成纳米二氧化锰(nMnO_(2)),然后与碳纳米管(CNTs)复掺水泥砂浆体系中,制备纳米水泥基热电复合材料(NTEC);最后将20个NTEC串联成1套热电发电模块,并结合电化学方法综合评价基于温差发电的NTEC热电模块直接用作海工结构钢筋CP系统电流供给源的可行性。结果表明:复掺有0.2wt%CNTs与5.0wt%nMnO_(2)的NTEC试件的热电系数、热电功率因数可分别达3612μV/℃和301.4μW·m^(-1)·℃^(-2),本征力学强度与耐久抗渗性得到保障;施加基于NTEC温差发电的CP,钢筋的腐蚀电位正移,腐蚀概率显著降低;施加基于NTEC热电模块的CP后能使钢筋腐蚀电流密度降低3个数量级,腐蚀电荷转移得到了抑制,腐蚀速率大为降低,实现海工结构钢筋CP的自供能,同时保障了其用作保护层的强度与耐久性。

关键词：海工结构阴极防护自供能纳米水泥基热电复合材料温差发电性能电化学性能

broadband strong optical dichroism in topological Dirac semimetals with Fermi velocity anisotropy

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Chinese Physics b 2020年第7期29卷 128-134页

作者： J Lim K J A Ooi C zhang L K ang Yee Sin ang Science Math and TechnologySingapore University of Technology and DesignSingapore School of Energy and Chemical Engineering Xiamen University MalaysiaSelangor Darul Ehsan 43900Malaysia College of Chemistry and Chemical Engineering Xiamen UniversityXiamen 361005China School of Physics University of WollongongNorthfields AvenueNew South Wales 2522Australia

Prototypical three-dimensional(3D)topological Dirac semimetals(DSMs),such as Cd3As2 and Na3bi,contain electrons that obey a linear momentum-energy dispersion with different Fermi velocities along the three orthogonal momentum *** being extensively studied in recent years,the inherent Fermi velocity anisotropy has often been neglected in the theoretical and numerical studies of 3D *** this omission does not qualitatively alter the physics of light-driven massless quasiparticles in 3D DSMs,it does quantitatively change the optical coefficients which can lead to nontrivial implications in terms of nanophotonics and plasmonics *** we study the linear optical response of 3D DSMs for general Fermi velocity values along each *** the signature conductivity-frequency scaling,σ(ω)∝ω,of 3D Dirac fermion is well-protected from the Fermi velocity anisotropy,the linear optical response exhibits strong linear dichroism as captured by the universal extinction ratio scaling law,Λi j=(vi/v j)^2(where i=j denotes the three spatial coordinates x,y,z,and vi is the i-direction Fermi velocity),which is independent of frequency,temperature,doping,and carrier scattering *** Cd3As2 and Na3bi3,an exceptionally strong extinction ratio larger than 15 and covering a broad terahertz window is *** findings shed new light on the role of Fermi velocity anisotropy in the optical response of Dirac semimetals and open up novel polarization-sensitive functionalities,such as photodetection and light modulation.

关键词： topological Dirac semimetal optical anisotropy linear dichroismn linear response theory