检索结果-南通市图书馆

Journal of Iron and Steel Research International 2018年第2期25卷 235-242页

作者： Cheng-hui Su Qiang-guo Li Xue-fei Huang wei-gang Huang College of Materials Science and Engineering SichuanUniversity Chengdu 610065 Sichuan China

The effect of bainite transformation and microstructure on the mechanical properties in 0.3%C bainitic steel was investigated via the heat treatment process of quenching at higher initial temperature and partitioning below martensite-start temperature. The results show that bainite transformation takes place with the partitioning time increasing during partitioning below martensite-start temperature. The microstructure of samples treated by this two-step quenching and partitioning process consists of lath bainite, lath martensite and retained austenite. This kind of multiphase microstructure exhibits better strength of 1420 MPa, ductility of 21.8 % and the product of strength and elongation of 30.8 GPa%. Furthermore, the excellent impact toughness of 103 J is exhibited by partitioning at 280 ℃ for 3 h. In addition, the coalescence of bainite platelets was found in the sample treated by partitioning for 8 h, leading to the deterioration of toughness.

关键词： Quenching and partitioning Bainitic steel Impact toughness Coalesced bainite

Genetic Bottlenecks of the Wild Chinese Giant Salamander in Karst Caves

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Herpetological Research 2017年第3期18卷 174-183页

作者： Jie WANG Hongxing ZHANG Feng XIE gang wei Jianping JIANG Chengdu Institute of Biology Chinese Academy of Sciences Shaanxi Institute of Zoology Guiyang University

The rarity of limestone cave species due to habitat degradation makes them of special interest in conservation *** wild Chinese Giant Salamander Andrias davidianus,an evolutionarily distinct and globally endangered species,are nearly all obligate into living in inaccessible mountain caves *** detected that only 14-29 breeders,with the effective population size of 9-25（5-44 of 95% confidence interval）,were in each of three caves,through genotyping 20 microsatellite loci on larvae that were flushed out of *** heterzygosity excess and M（ratios of allele number to allele size range） tests indicated severe genetic bottlenecks among *** mitochondrial,with only one or two haplotypes of D-loop region（770-771bp） in each population,and nuclear genetic structure showed clear divergence between *** the long life history,small population size,and genetic differentiationof the Chinese Giant Salamander,putting an end to poaching and recovering the karst ecosystem instead of releasing may be the sole measures to save this severely threated species.

关键词： limestone cave small population genetic drift Andrias davidianus subterranean habitat

Numerical study on the turbulent mixing of planar shock-accelerated triangular heavy gases interface

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2018年第5期34卷 855-870页

作者： wei-gang Zeng Jian-Hua Pan Yu-Xin Ren Yu-Tao Sun Department of Engineering Mechanics School of AerospaceTsinghua UniversityBeijing 100084China Institute of Applied Physics and Computational Mathematics Beijing 100094China

The interaction of a planar shock wave with a triangle-shaped sulfur hexafluoride (SF6) cylinder surrounded by air is numerically studied using a high resolution finite volume method with minimum dispersion and controllable dissipation *** vortex dynamics of the Richtmyer-Meshkov instability and the turbulent mixing induced by the KelvinHelmholtz instability are discussed.A modified reconstruction model is proposed to predict the circulation for the shock triangular gas-cylinder interaction *** typical stages leading the shock-driven inhomogeneity flow to turbulent mixing transition are *** the decoupled length scales and the broadened inertial range of the turbulent kinetic energy spectrum in late time manifest the turbulent mixing transition for the present *** analysis of variable-density energy transfer indicates that the flow structures with high wavenumbers inside the Kelvin-Helmholtz vortices can gain energy from the mean flow in ***,small scale flow structures are generated therein by means of nonlinear ***,the occasional 'pairing' between a vortex and its neighboring vortex will trigger the merging process of vortices and,finally,create a large turbulent mixing zone.

关键词： Richtmyer-Meshkov instability Kelvin-Helmholtz instability Length scale Turbulent mixing

Casimir Effect of Massive Scalar Field with Hybrid Boundary Condition in(1+1)-Dimensional Spacetime

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2009年第5期51卷 845-848页

作者： HE Xiao-Kai LIU Wen-Biao QIU wei-gang Department of Physics Institute of Theoretical Physics Beijing Normal University Beijing 100875 China Department of Physics Huzhou Teacher＇s College Huzhou 313000 China

The Casimir energy of massive scalar field with hybrid （Diriehlet-Neumann） boundary condition is calculated. In order to regularize the model, the typical methods named as mode summation method and Green＇s function method are used respectively. It is found that the regularized zero-point energy density depends on the scalar field＇s mass. When the field is massless, the result is consistent with previous literatures.

关键词： Casimir effect boundary condition massive scalar field regularization

院前急救与急诊治疗一体化治疗急性脑梗死的临床研究

在线全文

学校读者我要写书评

暂无评论

首都食品与医药 2024年第17期31卷 113-115页

作者：吴胜锋韦刚覃婵韦辉吴利芳韦仕荣广西河池市人民医院广西河池547000

目的探讨对急性脑梗死患者实施院前急救与急诊治疗一体化治疗的效果.方法此次研究选取河池市人民医院急诊科于2021年7月-2023年7月期间收治的60例急性脑梗死患者进行前瞻性研究,按照双色小球法分组,对照组30例接受常规检查和治疗,观察... 详细信息

目的探讨对急性脑梗死患者实施院前急救与急诊治疗一体化治疗的效果.方法此次研究选取河池市人民医院急诊科于2021年7月-2023年7月期间收治的60例急性脑梗死患者进行前瞻性研究,按照双色小球法分组,对照组30例接受常规检查和治疗,观察组30例接受院前急救与急诊治疗一体化治疗.观察两组的神经功能缺损评分、自理能力评分、并发症发生率以及治疗有效率.结果观察组治疗后的神经功能缺损评分较对照组更低,自理能力评分较对照组更高,并发症发生率较对照组更低,研究组治疗有效率96.66%,较对照组的76.66%更高,对比均有统计学意义(P<0.05).结论对急性脑梗死患者实施院前急救与急诊治疗一体化治疗措施,可以大幅提高对患者的急救效果,值得在临床上大力推广.

关键词：急性脑梗死院前急救与急诊治疗一体化神经功能自理能力并发症

Friction Estimation and Roll Force Prediction during Hot Strip Rolling

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 Iron and Steel Research International 2016年第12期23卷 1268-1276页

作者： wei-gang LI Chao LIU Ning FENG Xi CHEN Xiang-hua LIU College of Information Science and Engineering Wuhan University of Science and Technology Research Institute of Science and Technology Northeastern University

A mathematical model of friction coefficient was proposed for the roll force calculation of hot-rolled strips. The online numerical solving method of the roll force calculation formula based on the proposed friction model was developed and illustrated by the practical calculation case. Then, the friction coefficient during hot strip rolling was estimated from the measured roll force by force model inversion. And then, the expression of friction model was pro posed by analyzing the calculation process of stress state coefficient, and the model parameters were determined by the shared parameter multi-model nonlinear optimization method. Finally, the industrial experiments demonstrated the feasibility and effectiveness of the related models. The accuracy of the new roll force model based on the built friction model was much higher than that of the traditional Sims model, and it could be applied in the online hot rolling process control.

关键词： hot rolling roll force friction coefficient soft measurement multi objective optimization

在线全文

学校读者我要写书评

暂无评论

黔西北玄武岩中铜矿赋存形态与成矿机制研究

世界有色金属 2024年第14期 92-94页

作者：叶琼戴玉皇曹卫刚贵州鹏诚环境地质科技有限公司贵州贵阳550018 贵州省地矿局地球物理地球化学勘查院贵州贵阳550018

黔西北地区是我国重要的铜矿资源富集区,玄武岩中的铜矿是该地区主要的矿产类型。本研究通过对黔西北玄武岩中铜矿的赋存形态与成矿机制进行系统研究,旨在揭示该地区铜矿的形成过程和探索可能的找矿方向。研究结果表明,黔西北玄武岩中... 详细信息

黔西北地区是我国重要的铜矿资源富集区,玄武岩中的铜矿是该地区主要的矿产类型。本研究通过对黔西北玄武岩中铜矿的赋存形态与成矿机制进行系统研究,旨在揭示该地区铜矿的形成过程和探索可能的找矿方向。研究结果表明,黔西北玄武岩中的铜矿主要以矽卡岩型和斑岩型为主,黔西北玄武岩中铜矿的形成与岩浆活动和流体作用密切相关。本研究结果对于该地区的找矿工作具有重要的指导意义,为进一步开发利用该地区的铜矿资源提供科学依据。

关键词：黔西北玄武岩铜矿赋存形态成矿机制

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

卸载下超高性能混凝土加固盾构隧道数值模拟

低温建筑技术 2024年第2期46卷 139-143,148页

作者：李鑫魏纲徐天宝林双燕浙大城市学院土木工程系杭州310015 安徽理工大学土木建筑学院安徽淮南232001

为探究旁侧基坑开挖卸载扰动下超高性能混凝土(UHPC)加固盾构隧道的受力变形特征,采用MIDASGTSNX软件构建盾构管片三维精细化有限元模型,通过管片加固前后的收敛变形、螺栓应力、管片塑性变形等依据来评估UHPC对管片的加固效果。研究表... 详细信息

为探究旁侧基坑开挖卸载扰动下超高性能混凝土(UHPC)加固盾构隧道的受力变形特征,采用MIDASGTSNX软件构建盾构管片三维精细化有限元模型,通过管片加固前后的收敛变形、螺栓应力、管片塑性变形等依据来评估UHPC对管片的加固效果。研究表明UHPC加固对管片顶底收敛变形起有效限制作用,UHPC加固能够提高结构整体受力性能,且最大加固效率达50%;UHPC加固管片后,单环管片内邻接块与标准块间剪切作用的影响得到有效降低,管片接缝处变形受到限制;UHPC加固前后,管片塑性发展敏感区主要分布于左右腰部,可对这些位置采取局部加强措施。

关键词：盾构隧道 UHPC加固顶底收敛塑性变形

在线全文

学校读者我要写书评

暂无评论

关于锆-钢复合板制压力容器的风险探讨

世界有色金属 2024年第6期 207-209页

作者：魏侃张卫刚郗大来贺旭明西安优耐特容器制造有限公司陕西西安710201

锆在大多数有机酸、无机酸、强碱和某些熔融盐中都有优良的耐腐蚀性能,锆复合板制压力容器是近些年广泛应用于过氧化氢、醋酸、硝酸、尿素等化工行业的重要化工设备。因锆材不能与铁基材料熔焊,其材料要求、结构设计、制造检测方面都比... 详细信息

锆在大多数有机酸、无机酸、强碱和某些熔融盐中都有优良的耐腐蚀性能,锆复合板制压力容器是近些年广泛应用于过氧化氢、醋酸、硝酸、尿素等化工行业的重要化工设备。因锆材不能与铁基材料熔焊,其材料要求、结构设计、制造检测方面都比较特殊。本文结合笔者实际设计经验,从该类容器关键点的工程应用风险角度,探讨影响其安全性的材料应用、关键结构设计制造检测两方面的风险点及其风险控制。经过详细的阐释对比、应用论证,择选出具有最佳工程应用优势的主焊缝焊接结构及其检漏结构。

关键词：锆材锆复合板制压力容器风险控制焊接结构检漏结构

维普期刊数据库博看期刊

Altered amplitude of low-frequency fluctuations and default mode network connectivity in high myopia:a resting-state fMRI study

在线全文

学校读者我要写书评

暂无评论

International Journal of Ophthalmology(English edition) 2020年第10期13卷 1629-1636页

作者： Xue-wei Zhang Rong-Ping Dai gang-wei Cheng wei-Hong Zhang Qin Long Department of Radiology Translational Medical CenterPeking Union Medical College HospitalChinese Academy of Medical Sciences&Peking Union Medical CollegeBeijing 100730China Department of Interventional Radiology Emergency General HospitalBeijing 100028China Department of Ophthalmology Translational Medical CenterPeking Union Medical College HospitalKey Laboratory of Ocular Fundus DiseasesChinese Academy of Medical Sciences&Peking Union Medical CollegeBeijing 100730China

AIM:To analyze changes in amplitude of low-frequency fluctuations(ALFFs)and default mode network(DMN)connectivity in the brain,using resting-state functional magnetic resonance imaging(rs-fMRI),in high myopia(HM)***:Eleven patients with HM(HM group)and 15 age-and sex-matched non-HM controls(non-HM group)were *** were calculated and compared between HM group and non-HM *** component analysis(ICA)was conducted to identify DMN,and comparisons between DMNs of two groups were ***-of-interest(ROI)-based analysis was performed to explore functional connectivity(FC)between DMN ***:Significantly increased ALFFs in left inferior temporal gyrus(ITG),bilateral rectus gyrus(REC),bilateral middle temporal gyrus(MTG),left superior temporal gyrus(STG),and left angular gyrus(ANG)were detected in HM group compared with non-HM group(all P<0.01).HM group showed increased FC in the posterior cingulate gyrus(PCC)/precuneus(preCUN)and decreased FC in the left medial prefrontal cortex(mPFG)within DMN compared with nonHM group(all P<0.01).Compared with non-HM group,HM group showed higher FC between mPFG and bilateral middle frontal gyrus(MFG),ANG,and MTG(all P<0.01).In addition,HM patients showed higher FC between PCC/(preCUN)and the right cerebellum,superior frontal gyrus(SFG),left pre CUN,superior frontal gyrus(SFG),and medial orbital of the superior frontal gyrus(ORB supmed;all P<0.01).CONCLUSION:HM patients show different ALFFs and DMNs compared with non-HM subjects,which may imply the cognitive alterations related to HM.

关键词： functional magnetic resonance imaging high myopia default mode network amplitude of lowfrequency fluctuation