检索结果-南通市图书馆

Annealing-induced Grain Refinement in a Nanostructured Ferritic Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2012年第1期28卷 41-45页

作者： Limin Wang Zhenbo Wang sheng Guo Ke lu sheng Guo and Ke lu Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China

A nanostructured surface layer with a mean ferrite grain size of -8 nm was produced on a Fe-gCr steel by means of surface mechanical attrition treatment. Upon annealing, ferrite grains coarsen with increasing temperature and their sizes increase to -40 nm at 973 K. Further increasing annealing temperature leads to an obvious reduction of ferrite grain sizes, to -14 nm at 1173 K. The annealing-induced grain refinement is analyzed in terms of phase transformations in the nanostructured steel.

关键词： Nanostructured Surface mechanical attrition treatment (SMAT) Ferritic steel Grain refinement Austenitization

在线全文

学校读者我要写书评

暂无评论

呼伦湖浮游植物演变特征及影响因素

湖泊科学 2025年第1期37卷 50-60页

作者：兴月张生刘禹卢宗福史小红杨朝霞王殿飞赵耘溪内蒙古农业大学水利与土木建筑工程学院呼和浩特010018 内蒙古自治区水资源保护与利用重点实验室呼和浩特010018 内蒙古宁城县纪检监察工作保障中心赤峰024200

湖泊中浮游植物过度生长繁殖引起的水华现象日益频繁,严重威胁湖泊生态环境的健康与安全。近年来呼伦湖蓝藻水华覆盖面积有扩大的趋势,2022年呼伦湖蓝藻水华最严重时几乎覆盖了整个湖面,本文分别在春、夏和秋季调查了湖泊表、中、底层... 详细信息

湖泊中浮游植物过度生长繁殖引起的水华现象日益频繁,严重威胁湖泊生态环境的健康与安全。近年来呼伦湖蓝藻水华覆盖面积有扩大的趋势,2022年呼伦湖蓝藻水华最严重时几乎覆盖了整个湖面,本文分别在春、夏和秋季调查了湖泊表、中、底层水体的浮游植物种类、细胞密度、生物量和相关水质指标,共鉴定出浮游植物193种,隶属于8门113属,优势种共14种,物种组成表现为绿藻硅藻蓝藻型,其中春、秋季浮游植物种类数基本相当,夏季最少,但夏季的细胞密度最高,春、夏、秋季的浮游植物生物量分别为686、510和166 mg/L。春季浮游植物Shannon-Wiener多样性指数最高,夏季Margalef丰富度指数最高,春季Pielou均匀度指数最高,呼伦湖浮游植物群落特征及其季节性差异是湖泊水环境条件和气象因素共同作用的结果,相关性分析结果表明,主要影响因素依次为水温、总氮、总磷、pH、溶解氧、气温、蒸发量和风速等。

关键词：呼伦湖浮游植物群落特征水华影响因素

High-dynamics pulse-shaped signal simulation based on polynomial-based interpolation filters

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2017年第10期60卷 264-266页

作者： Shaozhong lu Yongqing WANG sheng LI Siliang WU School of Information and Electronics Beijing Institute of Technology

Dear editor,Baseband signal shaping is widely applied in satellite communication,GNSS,and TT&C systems as a fundamental technique[1].These systems work in high-speed dynamic environments,causing data rate variations b... 详细信息

关键词： High-dynamics pulse-shaped signal simulation based on polynomial-based interpolation filters PSF FIR Figure SRC

Effects of RRA Treatments on Microstructures and Properties of a New High-strength Aluminum-Lithium Alloy-2A97

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2007年第2期20卷 187-192页

作者： YUAN Zhi-shan lu Zheng XIE You-hua DAI sheng-long LIU Chang-sheng School of Materials ＆ Metallurgy Northeastern University Shenyang 110004 China Beijing Institute of Aeronautical Materials Beijing 100095 China

A new high strength 2A97 Al-Cu-Li-X alloy was subjected to triple-aging of retrogression and re-aging treatments （RRA）. Transmission electron microscopy （TEM）, differential scanning calorimetry （DSC）, and tensile tests were used to investigate the effects of RRA treatment on the microstructures and properties. DSC test reveals the reversion temperature range of the strengthening δ＇（Al3Li） phase. The results show that the microstructure consists of δ＇（Al3Li） phase, T1 （Al2CuLi） phase and θ″/θ′（Al2Cu） phase for 2A97 alloy treated by a triple-aging of a retrogression and re-aging treatment in the following order：（1） at 165℃×30 min, （2） at 220 ℃ or 240℃ × 15 min, （3） at 165℃×24 h. The plastic deformation, incorporated into the treatment after secondary high temperature aging, promotes the T1 precipitation during final re-aging. The tensile properties of the alloy treated by the retrogression and re-aging treatment reach the peak level of alloy single-aged at 165℃ in T6 temper.

关键词： 2A97 Al-Cu-Li-X alloy RRA treatments triple aging microstructure reversion

Characterization of Salmonella Enterica Serotype Typhimurium from Outpatients of 28 Hospitals in Henan Province in 2006

在线全文

学校读者我要写书评

暂无评论

Biomedical and Environmental Sciences 2009年第2期22卷 136-140页

作者： MIN ZHU ZHI-QIANG XIE LI-SHI ZHANG sheng-LI XIA WEI-zhong YANG lu RAN AND ZI-JUN WANG Huaxi School of Public Health Sichuan University Chengdu 610041 Sichuan China Henan Center for Disease Control and Prevention Zhengzhou 450016 Henan China Chinese Center for Disease Control and Prevention Beijing 100050 China

Objective To characterize the diarrheal patients with Salmonella typhimurium （S. typhimurium） infections and to set up the first baseline for S. typhimuri_um pulsed-field gel electrophoresis （PFGE） patterns in Henan province, thus laying a foundation for comprehensive surveillance of Salmonella in human as well as foods. Methods S. typhimurium isolates recovered from outpatients with diarrhea in Henan province from May to October of 2006 were characterized. Antimicrobial susceptibility tests of 8 antimicrobial agents and PFGE were carried out to analyze the S. typhimurium isolates. Results Twenty-four （0.9%） S. typhimurium isolates were identified from 2661 stool specimens of diarrheal cases. Eighty-eight percent of isolates showed resistance to at least one antimicrobial agent. The resistance to chloramphenicol （79%） was most common. Fifty-eight percent of isolates were resistant to ciprofloxacin. All the 14 ciprofloxacin-resistant isolates were resistant to more than five antimicrobial agents. Thirty-three percent of S. typhimurium isolates were resistant to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline （R-type ACSSuT）. Eight antimicrobia-resistant phenotypes were found among the 24 isolates in 16 PFGE patterns. Conclusion The rate of multidrug-resistant S. typhimurium is relatively high in S. typhimurium PFGE patterns of Henan province. Multidrug-resistant S. typhimurium should be considered a public health threat.

关键词： Salmonella typhimurium Outpatients Ciprofloxacin Multidrug-Resistant Pulsed-field gel electrophoresis

Neighbor Sum Distinguishing Total Choice Number of Planar Graphs without 6-cycles

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2020年第12期36卷 1417-1428页

作者： Dong Han ZHANG You lu sheng Gui ZHANG School of Mathematics and Statistics and Xi'an-Budapest Joint Research Center for Combinatorics Northwestern Polytechnical UniversityXi'an 710129P.R.China College of Mathematics and Computer Applications Shangluo UniversityShangluo 726000P.R.China

Pilsniak and Wozniak put forward the concept of neighbor sum distinguishing(NSD)total coloring and conjectured that any graph with maximum degreeΔadmits an NSD total(Δ+3)-coloring in *** 2016,Qu et *** that the list version of the conjecture holds for any planar graph withΔ≥*** this paper,we prove that any planar graph withΔ≥7 but without 6-cycles satisfies the list version of the conjecture.

关键词： Planar graphs neighbor sum distinguishing total choice number Combinatorial Nullstellensatz

Photoexcited singlet enhanced oxygen reduction reaction with high selectivity on the photosensitizer/layered double hydroxides nanocomposite

在线全文

学校读者我要写书评

暂无评论

Nano Research 2023年第4期16卷 5938-5945页

作者： Beibei Yang sheng Tao Xuefei Liu Jun lu State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing 100029China Tianjin University Tianjin 300072China

Oxygen reduction reaction(ORR)plays a pivotal role in advanced electrochemical energy conversion ***,the ORR conversion efficiency is extremely *** major obstacles originate from the adsorption and activation of O_(2)on the electrode surface.A novel nanocomposite catalyst,photosensitizers(PS)meso-tetraphenylporphyrin iron(III)chloride(FePcCl)/NiCoFe-layered double hydroxides(NiCoFe-LDHs)is designed in this ***,owing to excellent oxygen molecules activation ability and remarkable illumination absorption feature,FePcCl/NiCoFe-LDHs is employed to uncover the relationship between the intrinsic ORR activity and PS ***,the reaction mechanism of singlet 1O_(2)is proposed owing to the combination of electrochemical ORR catalysed via LDHs and *** boosted cathodic ORR properties exhibit singlet 1O_(2)dependent response arising from the synergistic effect to selectively produce active intermediates in alkaline *** work imparts the promising new mechanism about the high 4-electron ORR selectivity via material design,which will guide the development of photo-assisted energy conversion devices.

关键词： oxygen reduction reaction singlet 1O_(2) photosensitizers photo-assisted energy conversion layered double hydroxides

Disturbance rejection control based on acceleration projection method for walking robots

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第11期9卷 1531-1538页

作者： Xu-yang WANG Zhao-hong XU Tian-sheng lu School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China

This paper presents a disturbance rejection scheme for walking robots under unknown external forces and moments. The disturbance rejection strategy, which combines the inverse dynamics control with the acceleration projection onto the ZMP (zero moment point)-plane, can ensure the overall dynamic stability of the robot during tracking the pre-computed trajectories. Under normal conditions, i.e., the system is dynamically balanced, a primary inverse dynamics control is utilized. In the case that the system becomes unbalanced due to external disturbances, the acceleration projection control (APC) loop, will be activated to keep the dynamic stability of the walking robot through modifying the input torques. The preliminary experimental results on a robot leg demonstrate that the proposed method can actually make the robot keep a stable motion under unknown external perturbations.

关键词： Inverse dynamics Disturbance reiection ZMP (zero moment point)-plane Orthogonal projection Walking robot

Study on the Constitutive Model of Marble Based on the Conventional Triaxial Compression Test

在线全文

学校读者我要写书评

暂无评论

上海交通大学学报 2004年第Z2期38卷 8-13页

作者： Tian sheng-li lu Yun-de Ge Xiu-run School of Civil Engineering and Mechanics Shanghai Jiaotong University Shanghai200240China School of Civil Engineering and Mechanics Shanghai Jiaotong University Shanghai200240China School of Civil Engineering and Mechanics Shanghai Jiaotong University Shanghai200240China Institute of Rock and Soil Mechanics The Chinese Academy of Sciences Wuhan430071 China

The RMB-150B rock mechanics test system was employed to obtain the complete stress-strain test curves under confining pressures of 0-30MPa for marble samples from Ya'an ,Sichuan province. On the basis of former study and the convention triaxial pressure test results ,the complete procedures curves which described the relationships between yielding strength、 peak strength、 residual strength and confining pressure was obtained. Taking the strain softening of rock into account, the bilinear elastic-linear softening-residual perfect plasticity four-linear model was put forward in this paper on the basis of the test results and theory of plasticity. This model was adopted to describe the behaviors of marble in different phases under triaxial compression with the constitutive equation of strain softening phase as focus. The results indicated that the theoretic model fitted in well with the test results.

关键词： theory of plasticity conventional triaxial compression test constitutive model control equation linear softening bilinear elastic