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Accelerated k-nearest neighbors algorithm based on principal component analysis for text categorization

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Journal of Zhejiang University-Science C(Computers and Electronics) 2013年第6期14卷 407-416页

作者： min du Xing-shu CHEN School of Computer Science Sichuan University

Text categorization is a significant technique to manage the surging text data on the *** k-nearest neighbors(kNN) algorithm is an effective,but not efficient,classification model for text *** this paper,we propose an effective strategy to accelerate the standard kNN,based on a simple principle:usually,near points in space are also near when they are projected into a direction,which means that distant points in the projection direction are also distant in the original *** the proposed strategy,most of the irrelevant points can be removed when searching for the k-nearest neighbors of a query point,which greatly decreases the computation *** results show that the proposed strategy greatly improves the time performance of the standard kNN,with little degradation in ***,it is superior in applications that have large and high-dimensional datasets.

关键词： k-nearest neighbors(kNN) Text categorization Accelerating strategy Principal component analysis(PCA)

Hairy Root and Its Application in Plant Genetic Engineering

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Journal of Integrative Plant Biology 2006年第2期48卷 121-127页

作者： Zhi-Bi Hu min du Institute of Chinese Materia Medica Shanghai University of Traditional Chinese Medicine Shanghai 201203 China

Agrobacterium rhizogenes Conn. causes hairy root disease In plants. Hairy root-Infected A. rhizogenes Is characterlzed by a high growth rate and genetic stability. Hairy root cultures have been proven to be an efficient means of producing secondary metabolites that are normally biosyntheslzed In roots of differentiated plants. Furthermore, a transgenlc root system offers tremendous potential for introducing additional genes along with the RI plasmld, especially with modified genes, into medicinal plant cells with A. rhizogenes vector systems. The cultures have turned out to be a valuable tool with which to study the biochemical properties and the gene expression profile of metabolic pathways. Moreover, the cultures can be used to elucidate the Intermediates and key enzymes Involved In the biosynthesis of secondary metabolites. The present article discusses various appllcations of hairy root cultures in plant genetic engineering and potential problems aseoclsted with them.

关键词： Agrobacterium rhizogenes hairy root plant genetic engineering Ri plasmid secondary metabolites.

Microstructure and mechanical properties of X80 pipeline steels in different cooling schedules

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Acta Metallurgica Sinica(English Letters) 2010年第3期23卷 171-175页

作者： min ZHOU Linxiu du Xianghua LIU State Key Laboratory of Rolling Technology and Automation Northeastern University Shenyang 110819 China

The microstructures and mechanical properties of three X80 pipeline steel plates were investigated in this *** plates were hot rolled by two stages, and cooled by three different cooling schedules to obtain different microstructures and mechanical *** electron microscope（TEM） was used to observe the *** results indicated that the amount of polygonal ferrite（PF） and quasi-polygonal ferrite（QPF） decreased with decreasing of the finish cooling temperature（FCT）, while the amount and size of M-A islands were *** promoted the Charpy V-notch（CVN） impact toughness at-20℃, but not the drop weight tear testing（DWTT） property at-15℃, and decreased the strength of the steel.

关键词： Microstructure Mechanical properties Cooling schedule Relaxation

Research on the Pitting Mechanism of Dispersion-Strengthened High-Strength Steel Under Wet-Dry Cycling in a Marine Environment

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Journal of Ocean University of China 2021年第6期20卷 1459-1468页

作者： LI Ping GENG Yanming du min The Key Laboratory of Marine Chemistry Theory and Technology Ministry of EducationCollege of Chemistry and Chemical EngineeringOcean University of ChinaQingdao 266100China

due to the wet-dry cycling in the ocean tidal zone,the supply of dissolved oxygen and salt-containing particles were sufficient,so the corrosion was *** corrosion was a common form of localized *** paper studied the pitting corrosion mechanism of dispersion-strengthened high-strength steel under different wet-dry ratio *** Impedance Spectroscopy was used to study the changes of corrosion rate and electric double layer structure of the dispersionstrengthened high-strength *** electron microscope,Raman spectroscopy,electron probe microanalysis and laser confocal scanning microscope were used to observe the corrosion product morphologies,analyze the corrosion product compositions,analyze the secondary distribution of alloy elements in the corrosion products and analyze the pitting information of the steel after the corrosion products were *** results showed that the degree of the steel corrosion was slight when the wetting time was longer,the size and depth of the corrosion pits on the surface were *** was because the environment with longer wetting time made the corrosion products *** this environment,the conversion ofγ-FeOOH to Fe3O4 was *** addition,it could also promote the alloying elements to be more concentrated in the rust *** above phenomena hindered the further corrosion of the matrix by dissolved oxygen and Cl−in the seawater.

关键词： marine dispersion-strengthened high-strength steel wet-dry cycling pitting rust

Effect of sulfate-reducing bacteria on hydrogen permeation and stress corrosion cracking behavior of 980 high-strength steel in seawater

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Journal of Materials Science & Technology 2021年第33期92卷 109-119页

作者： Meiying Lv Xuchao Chen Zhenxin Li min du Key Laboratory of Marine Chemistry Theory and Technology Ministry of EducationCollege of Chemistry and Chemical EngineeringOcean University of ChinaQingdao 266100China

980 high-strength steel has been widely used in marine engineering structures due to its high strength and ***,it is easily affected by the harsh environmental conditions(such as the presence of sulfate-reducing bacteria,SRB),leading to the risk of stress corrosion cracking(SCC).In this paper,the effects of SRB and its metabolites on hydrogen permeation and SCC mechanism of 980 steel in seawater solution were investigated by slow strain rate tensile test,scanning electron microscope,Xray energy spectroscopy,Raman spectroscopy and Devanathan-Stachurski double electrolytic *** demonstrated that the SCC susceptibility of 980 steel was promoted in the presence of SRB,which was related to the cultivation time of the *** SRB were cultivated for 3 d and 6 d,the SCC mechanism was controlled by hydrogen-induced cracking(HIC);while the cultivation time extended to 11 d,the SCC of 980 steel was under the combined effect of the anodic dissolution(AD) and HIC *** cultivated for 16 d,the SCC of 980 steel was caused by the dominant *** the SRB accelerated hydrogen permeation under cathodic depolarization process and SRB assisted AD(pitting corrosion)played an enhancing role in promoting SCC susceptibility of 980 steel.

关键词： Stress corrosion cracking Sulfate-reducing bacteria Microbiologically influenced corrosion 980 High-strength steel Seawater

Influence of Dissolved Oxygen on the Protectiveness and Morphological Characteristics of Calcareous Deposits with Galvanostatic Polarization

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Journal of Ocean University of China 2017年第2期16卷 243-248页

作者： LI Chengjie du min GAO Rongjie The Key Laboratory of Marine Chemistry Theory and Technology Ministry of EducationCollege of Chemistry and Chemical EngineeringOcean University of ChinaQingdao 266100P.R.China

The influence of dissolved oxygen on calcareous deposits formed under galvanostatic polarization mode was *** the dissolved oxygen concentration was less than 7 mg L^(-1),the cathodic protection potential showed a plateau at the initial polarization,and then quickly shifted *** the dissolved oxygen was more than 9 mg L^(-1),the potential shifted negatively in a linear *** 168 h of polarization,the final protection potential shifted negatively with the decreasing dissolved oxygen *** deposition progress was monitored by electrochemical impedance spectroscopy,and only one single loop was found in Nyquist diagram,indicating deposits of ineffective protectiveness precipitation under the experimental *** protection factor of deposits increased with the decreasing dissolved oxygen concentration which was detected by linear polarization resistance *** cathodic electrochemical reaction could change very shortly from oxygen reduction to hydrogen evolution after cathodic protection under very low dissolved oxygen concentration,such as 1 mg L^(-1),resulting in the hydrogen bubbling from the metallic surface and the decrease of deposits protection *** by scanning electron microscopy and X-ray diffraction analysis demonstrated that the deposits were mainly of calcite under the experimental conditions,and that dissolved oxygen had no effect on the crystalline types of calcium carbonate.

关键词： seawater calcareous deposits dissolved oxygen galvanostatic cathodic protection

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节能燃气加热器中折流板的应力分析与优化

江苏大学学报（自然科学版） 2025年第1期46卷 43-49页

作者：杜敏张帅平张永春王跃成张嘉迪江苏大学能源与动力工程学院江苏镇江212013 江苏省特种设备安全监督检验研究院江苏南京210036

为了研究加热器中暴露在高温环境下折流板的应力分布规律与安全可靠性,基于有限元分析方法对其进行应力分析,选取危险截面路径进行应力线性化分析,并根据安全评定结果对折流板结构进行优化.结果表明:尖角造成的应力集中对折流板的应力... 详细信息

为了研究加热器中暴露在高温环境下折流板的应力分布规律与安全可靠性,基于有限元分析方法对其进行应力分析,选取危险截面路径进行应力线性化分析,并根据安全评定结果对折流板结构进行优化.结果表明:尖角造成的应力集中对折流板的应力分布影响较大,其薄膜应力P L过高是导致应力评定危险的主要原因;折流板整体应力大小随着燃料进口速度的增大而增高,温度与热应力大小呈正相关,在不同速度下应力变化趋势相似,换热管束与折流板连接处的结构不连续会造成应力升高;优化方案中,当钝化尖角后,折流板最大热应力降低16.7%,再覆盖热障涂层时的最大热应力较钝化尖角时降低44.5%,较原始结构降低53.7%,且整体热应力下降,优化后折流板强度评定为合格.

关键词：折流板温度场热流固耦合热应力应力评定热障涂层

On-chip fast mixing by a rotary peristaltic micropump with a single structural layer

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Science China(Technological Sciences) 2013年第4期56卷 1047-1054页

作者： du min MA ZengShuai YE XiongYing ZHOU ZhaoYing State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision Instruments and MechanologyTsinghua University

In this work,a rotary pump based micromixer for on-chip rapid mixing and liquid transportation is demonstrated and *** pumping and mixing are realized using a microfluidic chip with a single structural polydimethylsiloxane layer and a portable electric control *** rotary pump consists of an annular channel and is driven by a motor and *** flow field caused by the peristaltic movement of the channel membrane of the rotary pump is simulated and *** statistically calculating and comparing the normalized standard deviations of the flow velocity components in a microchannel,it is revealed that up-and-down mixing is the fastest,followed by segment mixing and parallel *** mixing styles,segment mixing and parallel mixing,were experimentally demonstrated using the *** pump achieved 90% of the mixing index in 1 s for the segment mixing *** for the parallel mixing type,the mixing index was up to 90% after 5 s,which is more than 100-fold improvement compared to conventional mixing by interfacial *** mixing speeds in both directions were improved prominently by increasing the rotational speed of the pump.

关键词： microfluidic mixing rotary pump magnetic driving

Relationship Among Microstructure and Properties and Heat Treatment Process of Ultra-High Strength X120 Pipeline Steel

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Journal of Iron and Steel Research International 2011年第3期18卷 59-64页

作者： ZHOU min du Lin-xiu LIU Xiang-hua State Key Laboratory of Rolling Technology and Automation Northeastern UniversityShenyang 110004LiaoningChina

The variation of heat treatments including directed quenching and tempering off-line after controlled rolling（DQT） and quenching off-line and tempering off-line after controlled rolling（RQT） with microstructure and mechanical properties of a low-carbon microalloyed steel was compared and *** DQT,the quenched steel was obviously banded microstructure,with increasing tempering temperature,lath martensite coarsened,the cusp carbide precipitated at grain boundaries,the yield strength fluctuated slightly,and the fracture-separation was *** impact toughness was better in the steel tempered at 500 ℃ for 1 *** RQT,with increasing tempering temperature,lath martensite degenerated,intragranular and intergranular finer precipitations with smaller than 30 nm precipitated and grew up and were distributed dispersedly,the stripe-like carbides were distributed at grain boundaries,and the yield strength and tensile strengthen decreased *** impact toughness of RQT process was much better than that of DQT process,and the comprehensive mechanical properties were better for the steel tempered at 500 ℃ for 1 h of RQT process.

关键词： X120 pipeline steel heat treatment microstructure mechanical property fracture-separation