Journal of Materials Research
The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.
关键词:
room-temperature
材料科学技术（英文）
The effect of interstitial hydrogen on the cohesion of the Al Sigma=11(113) grain boundary (GB) is investigated based on the thermodynamic model of Rice-Wang using the first-principles density function calculation. The results indicate that interstitial H behaves as an embrittler from "strengthening energy" analysis. The reduced GB cohesion due to the presence of H at the GB is attributed to the low affinity between H and Al, and the weakened bonding of Al atomic pairs perpendicular to GB plane.
关键词:
hydrogen;grain boundary;Al-Mg alloys;pseudopotentials;1st-principles
Xiaoguang LIU
,
Xiaowei WANG
材料科学技术（英文）
The effect of interstitial hydrogen on the cohesion of the Al ∑=11(113) grain boundary (GB) is investigated based on the thermodynamic model of Rice-Wang using the first-principles density function calculation. The results indicate that interstitial H behaves as an embrittler from "strengthening energy" analysis. The reduced GB cohesion due to the presence of H at the GB is attributed to the low affinity between H and Al, and the weakened bonding of Al atomic pairs perpendicular to GB plane.
关键词:
Hydrogen
,
null
,
null
赵洁
,
姚秉华
,
冯逸晨
功能材料
采用共沉淀法制备BiNbO4纳米棒。利用X射线粉末衍射仪（XRD）、透射电镜（TEM）、紫外-可见漫反射光谱（UV-Vis DRS）和热重分析（TG/DTA）对其结构、形貌和性质进行表征,并通过紫外-可见分光光度计分析BiNbO4纳米棒光降解罗丹明B来研究其光催化活性。结果表明以五氧化二铌和五水硝酸铋为原料制备得到正交相结构的BiNbO4纳米棒;BiN-bO4纳米棒具有较高的光催化活性,在紫外光下,pH值=3.05,催化剂用量为2g/L时能够有效地降解罗丹明B,降解率受到光源、催化剂浓度和溶液pH值的影响较大。
关键词:
共沉淀法
,
BiNbO4纳米棒
,
光催化
杨飒
,
郑志硕
量子电子学报
doi:10.3969/j.issn.1007-5461.2015.03.005
针对尺度不变特征变换(Scale-invariant feature transform,SIFT)算法在关键点特征描述向量阶段计算复杂并且维数较高的现象,提出了一种基于压缩感知理论的SIFT算法.通过压缩感知理论的稀疏特征表示方法,对SIFT关键点特征向量进行提取,将高维梯度导数向量降到低维稀疏特征向量,降低了关键点描述向量维度.采用欧式距离作为关键点的相似性度量, Best-Bin-First(BBF)数据结构避免穷举,使数据的运算量大为减少.实验结果表明,新算法对存在仿射变换的医学图像配准性能优于传统SIFT算法,与当前改进型的SIFT算法相比,本文算法的实时性明显增强.
关键词:
图像处理
,
图像配准
,
尺度不变特征变换
,
特征提取
,
稀疏随机投影
李伟国
,
祁超
,
刘立岩
,
赵大庆
应用化学
doi:10.3969/j.issn.1000-0518.2005.11.003
分别研究了二乙三胺五乙酸(DTPA)及2种衍生物二乙三胺五乙酸-双二甲酰胺(DTPA-BDMA)和二乙三胺五乙酸-双(异烟肼)(DTPA-BIN)对乳酸脱氢酶活性及酶促反应动力学的影响.结果表明,它们均可以抑制脱氢酶的活性,其抑制类型为竞争性的抑制作用,抑制常数分别为3.37、7.41、8.52μmol/L.紫外差谱结果表明,DTPA及其衍生物可以和酶分子作用,其羧基部分被包埋到分子内部,在酶分子的结合部位存在芳香族的氨基酸残基.DTPA与脱氢酶作用后使酶分子中的色氨酸荧光强度减弱,对酪氨酸的荧光没有明显影响.
关键词:
二乙三胺五乙酸
,
乳酸脱氢酶
,
酶学动力学
,
紫外差谱
,
荧光光谱
Physical Review B
By use of the linear-combination-of-atomic-orbital (LCAO) method for a cluster model, we studied the electronic structure of gamma-from Sigma 11 [1 (1) over bar0](11 (3) over bar) grain boundary doping with N and Mn atoms. The effect of the segregation on the cohesion of the grain boundary is investigated based on the Rice-Wang thermodynamic model. It is found that N could not only largely enhance the cohesion of the grain boundary but also eliminate the detrimental effect of Mn. The cosegregation effect of Mn and N on the cohesion of the grain boundary depends on where they segregate. Nitrogen could be reliably used in alloyed steels as an efficient strengthening element.
关键词:
electronic-structure;phosphorus segregation;stainless-steel;embrittlement;austenite;nitrogen;boron;impurities;fracture;metals
周晓宏
,
刘红军
,
刘鹏
功能材料
优化技术是一种以数学为基础,可用来求解各种工程问题最优解的应用技术.本文利用磁流变阻尼器动态特性数据,采用遗传算法进行阻尼器模型参数识别优化过程,最终将得到的磁流变阻尼器模型参数用于土木工程结构振动控制研究.已建立的磁流变阻尼器的动力特性将在不同的电场强度和变化的位移幅度下进行测试,可以得到在不同位移和速度下恢复力的滞回曲线,建立Bouc-Wen模型.把根据试验得到的滞回曲线和使用遗传算法对模型参数进行优化的结果进行比较可知,这种模型的参数可以以十分小的误差得到优化.
关键词:
遗传算法
,
阻尼器
,
参数识别
