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Statistical characteristics and classification of ionospheric mid-latitude trough as revealed by the observations of DMSP-F18

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Earth and Planetary Physics 2025年第1期9卷 137-147页

作者： Yi liu JiuHou Lei FuQing Huang Su zhou School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China School of Science Guiyang UniversityGuiyang 550005China

Statistical characteristics and the classification of the topside ionospheric mid-latitude trough are systemically analyzed,using observations from the Defense Meteorological Satellite Program F18(DMSP-F18)*** data was obtained at an altitude of around 860 km in near polar orbit,throughout *** study identified the auroral boundary based on the in-situ electron density and electron spectrum,allowing us to precisely determine the location of the mid-latitude *** differs from most previous works,which only use Total Electron Content(TEC)or in-situ electron *** our study,the troughs exhibited a higher occurrence rate in local winter than in summer,and extended to lower latitudes with increasing geomagnetic *** was found that the ionospheric mid-latitude trough,which is associated with temperature changes or enhanced ion drift,exhibited distinct ***,the ionospheric mid-latitude troughs related to electron temperature(Te)peak were located more equatorward of auroral oval boundary in winter than in *** ionospheric mid-latitude troughs related to Te-maximum were less frequently observed at 60−70°S magnetic latitude and 90−240°E ***,the troughs related to ion temperature(Ti)maximums were observed at relatively higher latitudes,occurring more frequently in *** addition,the troughs related to ion velocity(Vi)maximums could be observed in all *** troughs with the maximum-Ti and maximum-Vi were located closer to the equatorward boundary of the auroral oval at the nightside,and in both *** implies that enhanced ion drift velocity contributes to increased collisional frictional heating and enhanced ion temperatures,resulting in a density depletion within the trough region.

关键词： topside ionosphere mid-latitude trough ionospheric main trough auroral oval boundary temperature maximum

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Orientationability and Practical Orientationability Analysis of a Special Class of the Stewart-Gough Parallel Manipulators

Orientationability and Practical Orientationability Analysis...

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2010 Chinese Control and Decision Conference

作者： Yi Cao,Weixi Ji,Zhihui liu,hui zhou,Mengsi liu School of Mechanical Engineering,Jiangnan University,1800 Lihu Avenue,Wuxi,Jiangsu 214122,China

＜正＞This paper mainly addresses the orientation-singularity and orientationability analyses of a special class of the Stewart-Gough parallel *** on the half-angle transformation,an analytical polynomial expression of thirteen degree in the moving platform orientation parameters is derived,which represents the orientation-singularity locus of this class of the manipulator at a given position,graphical representations of the orientation-singularity locus of the manipulator are given to illustrate the *** is shown that for this special class of the Stewart-Gough manipulators, it must exist a nonsingular orientation void in the orientation space around the orientation origin for each position in the *** a new performance index which describes the orientationability of the parallel manipulator at a given position is ***,effects of the design parameters of the moving platform on the orientationability of the manipulator are also presented in detailed in this *** on the research on the orientation-singularity and nonsingular orientation void of the manipulator,another novel performance index representing the practical orientationability of this special class of the manipulator at a given position in the position-workspace is introduced,where singularities,the limitations of active and passive joints and the link interference are all taken into ***,the practical orientationability of this special class of the Stewart-Gough parallel manipulators is also analyzed at length over the whole position-workspace of the manipulator.

关键词： Orientationability Practical Orientationability Parallel Manipulator

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High-dimensional large-scale mixed-type data imputation under missing at random

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Science China Mathematics 2025年

作者： Wei liu Guizhen Li Ling zhou Lan Luo School of Mathematics Sichuan University Center of Statistical Research and School of Statistics Southwestern University of Finance and Economics Department of Statistics and Actuarial Science University of Iowa

Missingness in mixed-type variables is commonly encountered in a variety of areas. The requirement of complete observations necessities data imputation when a moderate or large proportion of data is ***, inappropriate imputation would downgrade the performance of machine learning algorithms, leading to bad predictions and unreliable statistical inference. For high-dimensional large-scale mixed-type missing data, we develop a computationally efficient imputation method, missing value imputation via generalized factor models（MIG）, under missing at random. The proposed MIG method allows missing variables to be of different types,including continuous, binary, and count variables, and are scalable to both data size n and variable dimension p while existing imputation methods rely on restrictive assumptions such as the same type of missing variables,the low dimensionality of variables, and a limited sample size. We explicitly show that the imputation error of the proposed MIG method diminishes to zero with the rate Op(max{n-1/2, p-1/2}) as both n and p tend to infinity. Five real datasets demonstrate the superior empirical performance of the proposed MIG method over existing methods that the average normalized absolute imputation error is reduced by 5.3%–34.1%.

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Effects of mesoscale gravity waves on sporadic E simulated by a one-dimensional dynamic model

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Earth and Planetary Physics 2025年第1期9卷 1-9页

作者： Xu zhou ZeZhong Li XinAn Yue LiBo liu Key Laboratory of Earth and Planetary Physics/Heilongjiang Mohe National Geophysical Observatory/Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of Sciences(CAS)Beijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China CAS Center for Excellence in Comparative Planetology/CAS Key Laboratory of Geospace Environment/Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefei 230026China

In addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively *** this article,we discuss the effects of mesoscale GWs on the Es layers determined by using a newly developed model,MISE-1D(one-dimensional Model of Ionospheric Sporadic E),with low numerical dissipation and high *** by the wind fields resolved by the high-resolution version of the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension(WACCM-X),the MISE-1D simulation revealed that GWs significantly influence the evolution of the Es layer above 100 km but have a very limited effect at lower *** effects of GWs are diverse and complex,generally including the generation of fluctuating wavelike structures on the Es layer with frequencies similar to those of the *** mesoscale GWs can also cause increases in the density of Es layers,or they can disperse or diffuse the Es layers and increase their *** addition,the presence of GWs is a key factor in sustaining the Es layers in some cases.

关键词： sporadic E ion tidal layer gravity waves numerical simulation

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基于模糊负荷聚类的不良负荷数据辨识与修正

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中国电力 2013年第10期46卷 29-34页

作者：刘辉舟周开乐胡小建国网安徽省电力公司铜陵供电公司安徽铜陵244000 合肥工业大学管理学院安徽合肥230009 合肥工业大学过程优化与智能决策教育部重点实验室安徽合肥230009

为辨识和修正不良负荷数据,在利用模拟退火遗传算法优化的模糊C均值(Fuzzy C-Means,FCM)算法进行负荷曲线聚类的基础上,提出将待测曲线与相应特征曲线进行比较计算差量系数的方法。差量系数大于电力公司确定的阈值的负荷点即为不良负荷... 详细信息

为辨识和修正不良负荷数据,在利用模拟退火遗传算法优化的模糊C均值(Fuzzy C-Means,FCM)算法进行负荷曲线聚类的基础上,提出将待测曲线与相应特征曲线进行比较计算差量系数的方法。差量系数大于电力公司确定的阈值的负荷点即为不良负荷数据。通过算例验证表明,该方法克服了统计历史数据中不良数据的影响,提高了不良数据辨识的可操作性和实用性。同时提出了考虑不良数据测量点外所有其他测量点负荷信息的不良数据修正方法,与仅考虑不良数据测量点前后2个测量点负荷信息的修正方法相比,提高了不良数据修正的精确性和有效性。

关键词：不良负荷数据辨识与修正负荷曲线聚类模糊C均值算法

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A matrix metalloproteinase-responsive hydrogel system controls angiogenic peptide release for repair of cerebral ischemia/reperfusion injury

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Neural Regeneration Research 2025年第2期20卷 503-517页

作者： Qi liu Jianye Xie Runxue zhou Jin Deng Weihong Nie Shuwei Sun Haiping Wang Chunying Shi Department of Human Anatomy Histology and EmbryologySchool of Basic MedicineQingdao UniversityQingdaoShandong ProvinceChina Department of Neurology The Affiliated Hospital of Qingdao UniversityQingdaoShandong ProvinceChina Department of General Practice The Affiliated Hospital of Qingdao UniversityQingdaoShandong ProvinceChina

Vascular endothelial growth factor and its mimic peptide KLTWQELYQLKYKGI(QK)are widely used as the most potent angiogenic factors for the treatment of multiple ischemic ***,conventional topical drug delivery often results in a burst release of the drug,leading to transient retention(inefficacy)and undesirable diffusion(toxicity)in ***,a drug delivery system that responds to changes in the microenvironment of tissue regeneration and controls vascular endothelial growth factor release is crucial to improve the treatment of ischemic *** metalloproteinase-2(MMP-2)is gradually upregulated after cerebral ***,vascular endothelial growth factor mimic peptide QK was self-assembled with MMP-2-cleaved peptide PLGLAG(TIMP)and customizable peptide amphiphilic(PA)molecules to construct nanofiber hydrogel ***-TIMP-QK was found to control the delivery of QK by MMP-2 upregulation after cerebral ischemia/reperfusion and had a similar biological activity with vascular endothelial growth factor in *** results indicated that PA-TIMP-QK promoted neuronal survival,restored local blood circulation,reduced blood-brain barrier permeability,and restored motor *** findings suggest that the self-assembling nanofiber hydrogel PA-TIMP-QK may provide an intelligent drug delivery system that responds to the microenvironment and promotes regeneration and repair after cerebral ischemia/reperfusion injury.

关键词： angiogenesis biomaterial blood-brain barrier cerebral ischemia/reperfusion injury control release drug delivery inflammation QK peptides matrix metalloproteinase-2 neuroprotection self-assembling nanofiber hydrogel

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区域性高校教学质量观研究与实践——以通化师范学院为个案的分析

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通化师范学院学报 2007年第11期28卷 5-7页

作者：刘惠洲通化师范学院教务处吉林通化134002

该文以作者所在学校为研究与实践对象,论述了区域性高校教学质量观形成的理论基础、思想基础、历史基础和现实基础及其内容,阐明了区域性高校教学质量观研究与实践的意义,尤其是涵述了其在服务社会主义新农村建设中的作用。

关键词：区域性高校教学质量观研究实践

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教师职业道德课程教学模式的思考与实践

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通化师范学院学报 2007年第9期28卷 60-61,110页

作者：刘惠洲通化师范学院教务处吉林通化134002

文中阐释了教师职业道德课程教学模式的确立依据、基本内容和实践意义。

关键词：教师职业道德课程教学模式思考实践

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在学分制培养方案制定中深化完善实践教学体系的六大方略

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通化师范学院学报 2007年第1期28卷 70-72页

作者：刘惠洲通化师范学院教务处吉林通化134002

文中阐释了深化和完善实践教学体系的基本思路,概述了实践教学方案合理制定的六大方略内容。

关键词：学分制培养方案深化完善实践教学体系方略

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Ag在Si(111)表面二维生长有序化动力学研究

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物理学报 1996年第8期45卷 1380-1389页

作者：李明徐明刘惠周中山大学物理系广州510275

利用自制的高分辨率衍射斑角分布测量仪对低能电子衍射斑进行测量,研究Ag在Si(111)表面的有序化规律.结果表明,Ag 3^(1/3)畴在生长过程中,满足标度不变性,是一种自相似的生长过程,在生长初期,它的生长指数近似为1/2,并提出了Ag从Ag(111... 详细信息

利用自制的高分辨率衍射斑角分布测量仪对低能电子衍射斑进行测量,研究Ag在Si(111)表面的有序化规律.结果表明,Ag 3^(1/3)畴在生长过程中,满足标度不变性,是一种自相似的生长过程,在生长初期,它的生长指数近似为1/2,并提出了Ag从Ag(111)岛向外扩散形成Ag 3^(1/3)畴的生长机制.还提出利用光助退火以在较低温度下获得完善的表面结构.

关键词：硅表面外延银二维生长有序化

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