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高速铁路接触网高精度施工技术研究

中国高新科技 2024年第10期 103-105页

作者：周治华中铁建电气化局集团第四工程有限公司湖南长沙410000

随着电气工程技术的快速发展,国内电气化铁路建设取得了长足的进步,新型技术设备在高速铁路接触网中的应用愈发广泛,实现了高铁接触网高精度施工。基于此,文章在概述高铁接触网高精度施工技术要点的基础上,提出降低高铁接触网施工偏差... 详细信息

随着电气工程技术的快速发展,国内电气化铁路建设取得了长足的进步,新型技术设备在高速铁路接触网中的应用愈发广泛,实现了高铁接触网高精度施工。基于此,文章在概述高铁接触网高精度施工技术要点的基础上,提出降低高铁接触网施工偏差的措施,为确保高铁稳定供电提供理论依据。

关键词：高铁接触网高精度施工技术

Green Catalysis for Three-Component Reaction of Carbon Dioxide, Propargylic Alcohols and Nucleophiles

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物理化学学报 2018年第8期34卷 838-844页

作者： zhou zhihua XIA Shumei HE Liangnian State Key Laboratory and Institute of Elemento-Organic Chemistry College of Chemistry Nankai University Tianjin 300071 P. R. China Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) Nankai University Tianjin 300071 E R. China.

Carbon dioxide (CO_2) is one of the main greenhouse gases that can be utilized as a useful C1 source owing to its abundance, non-toxicity, and renewability. In fact, the transformation of carbon dioxide into valuable organic molecules has attracted considerable attention over the past decades. One-pot multicomponent reactions generally proceed with more than two different raw materials reacting in one pot, thus simplifying the reaction in operation and workup. In this regard, a three-component reaction of CO_2, propargylic alcohols, and nucleophiles such as amines, water, and alcohols, to prepare useful carbonyl compounds (e.g., carbamates, oxazolidinones, α-hydroxyl ketones, and organic carbonates) is particularly appealing because of the advantages of step and atom economy. From a mechanistic point of view, the three-component reaction of CO_2, a propargylic alcohol, and a nucleophile is a type of cascade reaction, involving the carboxylative cyclization of CO_2 and propargylic alcohol, and subsequent reaction of a nucleophile with the in situ formed α-alkylidene cyclic carbonate. On the other hand, reactions involving CO_2 are generally thermodynamically unfavorable because of the thermodynamic stability and kinetic inertness of CO_2. Cyclic carbonates are widely used in organic synthesis, and their preparation from vicinal diols and CO_2 represents a green synthetic method because biomass is utilized as the source of vicinal diols. However, the low yields of cyclic carbonates are obtained in most cases because of thermodynamic limitations and deactivation of the catalyst by water, which is the co-product of cyclic carbonates. The most commonly used method to improve the yields of cyclic carbonates involves the addition of dehydrating agents. However, decreased selectivity is often observed because of the side reaction of vicinal diols with the hydrolysis products of the dehydrating agent. In addition, the reaction of 2-aminoethanols and CO_2 to obtain the corres

关键词：温室气体绿色化学环境保护合成方法邻二醇

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地球化学数据库管理平台的建设与思考

中国地震 2024年第1期40卷 173-183页

作者：田雷周志华晏锐冯晓博中国地震台网中心北京100045

为更好地发挥地球化学数据及方法在异常分析及震情跟踪研判中的作用,提高地球化学数据获取的便利性及数据存储的可靠性,规范异常核实及流动观测等地球化学样品的采集及检测流程,实现地球化学数据的自动分析及相关图件的自动绘制,中国地... 详细信息

为更好地发挥地球化学数据及方法在异常分析及震情跟踪研判中的作用,提高地球化学数据获取的便利性及数据存储的可靠性,规范异常核实及流动观测等地球化学样品的采集及检测流程,实现地球化学数据的自动分析及相关图件的自动绘制,中国地震台网中心建立了基于Linux系统的地球化学数据库管理平台,该平台应用数据库、地理信息系统(GIS)、WebGIS等技术,集成了样品送检、实验室检测、报告产出、数据存储筛选下载分析、图件绘制等功能,利用Piper图、Na-K-Mg三角图、同位素分析等方法,分析不同样品的地球化学特征,并给出相关图件。平台自推广以来,收集了大量的地球化学数据,提升了数据的可利用性,降低了地球化学数据分析的技术门槛,在异常性质分析及震情跟踪研判中发挥了作用。

关键词：地球化学数据数据库系统平台

Preparation and bioactivity of sol-gel macroporous bioactive glass

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Journal of University of Science and Technology Beijing 2008年第3期15卷 290-296页

作者： zhihua zhou Jianming Ruan Jianpeng Zou Zhongcheng zhou State Key Laboratory for Powder Metallurgy Central South University Changsha 410083 China College of Chemistry and Chemical Engineering Hunan University of Science and Technology Xiangtan 411201 China

Bioactive glass is well known for its ability of bone regeneration, and sol-gel bioactive glass has many advantages compared with melt-derived bioactive glass. 3-D scaffold prepared by the sol-gel method is a promising substrate material for bone tissue engineering and large-scale bone repair. Porous sol-gel glass in the CaO-SiO2-P205 system with macropores larger than 100 μm was prepared by the addition of stearic acid as a pore former. The diameter of the pore created by the pore former varied from 100 to 300 μm. The formation of a hydroxyapatite layer on the glass was analyzed by studying the surface of the porous glass by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and Raman spectra after they had been immersed in simulated body fluid （SBF） for some time, and the porous glass shows good bioactivity.

关键词： macroporous glass sol-gel in vitro bioactivity bone repair

A Remark on Steinness

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Chinese Annals of Mathematics,Series B 2007年第2期28卷 161-164页

作者： Chaohui zhou zhihua CHEN Department of Applied Mathematics Tongji University Shanghai 200092 China.

In this paper, the authors prove that if Mn is a complete noncompact Kaehler manifold with a pole p, and its holomorphic bisectional curvature is asymptotically nonnegative to p, then it is a Stein manifold.

关键词： Holomorphic bisectional curvature Plurisubharmonic Smooth Exhausting

High efficient moving object extraction and classification in traffic video surveillance

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Journal of Systems Engineering and Electronics 2009年第4期20卷 858-868页

作者： Li zhihua zhou Fan Tian Xiang Chen Yaowu Inst. of Advanced Digital Technology and Instrument Zhejiang Univ. Hangzhou 310027 P. R. China

Moving object extraction and classification are important problems in automated video surveillance systems. A background model based on region segmentation is proposed. An adaptive single Gaussian background model is used in the stable region with gradual changes, and a nonparametric model is used in the variable region with jumping changes. A generalized agglomerative scheme is used to merge the pixels in the variable region and fill in the small interspaces. A two-threshold sequential algorithmic scheme is used to group the background samples of the variable region into distinct Gaussian distributions to accelerate the kernel density computation speed of the nonparametric model. In the feature-based object classification phase, the surveillance scene is first partitioned according to the road boundaries of different traffic directions and then re-segmented according to their scene localities. The method improves the discriminability of the features in each partition. AdaBoost method is applied to evaluate the relative importance of the features in each partition respectively and distinguish whether an object is a vehicle, a single human, a human group, or a bike. Experimental results show that the proposed method achieves higher performance in comparison with the existing method.

关键词： background model nonparametric model adaptive single Gaussian model object classification

Learnability of multi-instance multi-label learning

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Chinese Science Bulletin 2012年第19期57卷 2488-2491页

作者： WANG Wei zhou zhihua National Key Laboratory for Novel Softwaye Technology Nanjing UniversityNanjing 210046China

Multi-instance multi-label learning(MIML) is a new machine learning framework where one data object is described by multiple instances and associated with multiple class *** the past few years,many MIML algorithms have been developed and many applications have been ***,there lacks theoretical exploration to the learnability of *** this paper,through proving a generalization bound for multi-instance single-label learner and viewing MIML as a number of multi-instance single-label learning subtasks with the correlation among the labels,we show that the MIML hypothesis class constructed from a multi-instance single-label hypothesis class is PAC-learnable.

关键词：机器学习多实例标签易学数据对象 ML算法

广州市推进粤港澳大湾区综合客运交通发展对策研究

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公路与汽运 2024年第5期40卷 33-36页

作者：欧阳剑周志华广州市交通规划研究院有限公司广东广州510030

分析广州航空、铁路和公路客运在大湾区综合客运交通中的构成地位、共享服务水平,结合新时代大湾区发展要求,分析广州市综合客运交通的差距,认为大湾区机场群国际竞争力韧性不足、大湾区对外通道标准不高、内部互联互通水平有待提升,提... 详细信息

分析广州航空、铁路和公路客运在大湾区综合客运交通中的构成地位、共享服务水平,结合新时代大湾区发展要求,分析广州市综合客运交通的差距,认为大湾区机场群国际竞争力韧性不足、大湾区对外通道标准不高、内部互联互通水平有待提升,提出广州市促进大湾区世界级机场群建设、提升大湾区整体对外辐射能力、高标准建设大湾区直连直通轨道网络和推进大湾区关键性对外高速公路扩容提质等发展建议。

关键词：城市交通综合客运交通机场群多模式轨道交通直连直通高速公路

Rheological responses of fumed silica suspensions under steady and oscillatory shear

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Science China(Technological Sciences) 2009年第4期52卷 910-915页

作者： YANG HaiLin RUAN JianMing ZOU JianPeng WU QiuMei zhou ZhongCheng zhou zhihua State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

Rheological experiments under steady and oscillatory shear were conducted for fumed silica suspen- sions in polyethylene glycol. Under steady shear the shear-thinning and thickening response were exhibited and the flow exponent N was determined. With the increase of concentration the flow exponent N showed a rapid increase, and it increased dramatically when the discontinuous shear-thickening took place. Oscillatory shear experiments were conducted at constant frequency and constant amplitude strain, respectively. The shear-thinning and the discontinuous shear-thickening behavior were observed under different constant frequencies from 10 to 80 rad/s. The correlation between complex modulus (G*) and sweep frequency (ω) was illuminated at γ =750%. It was found that the correlation between G* and ω could be fitted by equation: G*∝ωn. The indexes in shear-thinning region and shear-thickening were determined. The indexes were similar to some extent at shear-thinning region and increased dramati- cally to a much higher value when the shear-thickening occurred,especially at higher weight fractions. The behaviors can be qualitatively explained as follows: the shear-thinning owes to decrease of viscos- ity, which results from disruption of the aggregates; the cluster theory attributes the shear-thickening to the formation of metastable, flow induced clusters, which block the system.

关键词： fumed silica suspension shear-thickening steady shear dynamic oscillatory shear rheological response