Influence of Mg_5Ga_2 compound on microstructures and electrochemical properties of Mg-5%Hg-22%Ga alloy

The Mg-5%Hg-22%Ga(mole fraction) alloy was melted.Aging at 573-673 K for different times was carried out to ensure the fine dispersion of the Mg_5Ga_2 compound.Scanning electron microscopy(SEM),X-ray diffractometry(XRD) and energy spectrum analysis(ESA) were employed to characterize the microstructures and phases of the Mg-5%Hg-22%Ga alloy.The electrochemical and corrosion behaviors of the above alloy were studied by potentiodynamic,galvanostatic and electrochemical impedance spectroscopy(EIS) measuremen...     

Cellulose nanocrystals as green fillers to improve crystallization and hydrophilic property of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

The green nanocomposites of poly(3-hydroxybutyrate-co-3-hyd roxyvalerate) (PHBV) with various cellulose nanocrystals (CNCs) contents were prepared by solution casting method. Th e effects of CNCs on the crystallization behavior, spherulitic morphology, crystal structure and hydrophilic property of PHBV were studied by differential scanning calorimeter (DSC), polarized optical microscope (POM), wide-angle X-ray diffraction (WAXD) and static water contact angle measurement. It is found that the CNCs act as an effective nucleation agent for crystallization of PHBV, inducing an increase in the melt crystallization tempera ture of the nanocomposites. A study of the non-isothermal crystallizatio n kinetics further illustrated that overall crystallization rate of PHBV in the nanocomposites was faster than that of neat PHBV, but exhibited a decrease in the crystallinity and the spherulite size of PHBV. Furthermore, the contact angle decreased from 60.1° for neat PHBV to 32.5° for the nanocomposites with 10% CNCs (mass fraction).     

具有边界记忆项波动方程的初边值问题

研究一类具有边界记忆项的非线性波动方程的初边值问题,利用Galerkin方法、紧性原理得到了整体解的存在性,利用补偿能量法得到了解的渐近性.     

纳米复合稀土永磁体Pr9-xDyxFe84.4-yCoyGa1Mn0.6B5（x=0,1,y=0,8）的反磁化行为和磁粘滞性

用电弧熔炼法制备了Pr9Fe84.4 B5Mn0.6 Ga1和Pr8Dy1Fe76.4 Co8B5Mn0.6 Ga1合金铸锭,然后利用熔体快淬法获得相应的薄带样品.分析了起始磁化,反磁化过程及样品的磁粘滞性,结果表明,两样品在室温下表现为单一硬磁相磁化行为,在低温下表现为双相行为.Co和Dy的联合添加使软磁相的晶粒尺寸减小,而晶粒间交换耦合作用增强,样品的形核场增大.磁粘滞性研究表明,Co和Dy联合掺杂的样品磁粘滞系数的增大是由软磁晶粒大小的减小导致热激活体积增加而引起的.     

数据库过量下载行为分析及规范

数据库过量下载在我国图书馆特别是高校图书馆频繁发生,引发了各界的广泛关注。对数据库过量下载行为进行了界定,分析了数据库过量下载行为的原因,提出了规范该行为的对策和建议。     

Activity sequence modes for Web services and verifications

Behavior requirement expression and its satisfiability verification for composite Web services is one of the ongoing issues in service computing.In this paper,the concept of behavior specifications based on activity sequence is proposed to express one kind of behavioral requirements for composite Web services.Its basic element is activity sequence.The method to express such behavioral requirements by behavioral modes is presented.Five behavioral modes used in this method are adopted.Through mapping modes to Labeled Transition Systems(LTSs),these modes are encoded with exact operation semantics.Then,the sufficient and necessary conditions as well as the checking algorithm for satisfiability of behavioral modes are given.Finally,an example analysis is presented.The result indicates that the behavioral requirements based on activity sequence are more suitable for the case of composite Web service than those based on activity or scenario.The behavioral modes expressions are concise and the satisfiability checking is effective by the given algorithm.     

点粘接双圈图的Hosoya指标的最大值序列

点粘接双圈图是指两个圈有一个公共的顶点的图.根据已有的结果,通过对Hosoya指标的理论和性质的研究,给出了点粘接双圈图Hosoya指标的最大值序列及其最大值的图.     

群机器人Flocking行为研究综述

主要回顾了群机器人自组织flocking行为的研究。首先,介绍群机器人学的含义及关键特征;然后,指出flocking行为在生物学上及机器人学上的意义,之后对目前的研究现状进行介绍。最后,按照以下的三个分类对群机器人flocking行为进行总结:行为控制,硬件设备及交流策略。     

通过执行倒闸操作标准化程序预防误操作事故的发生

分析了误操作事故发生的原因,阐述了违章行为的主要表现,提出了倒闸操作的标准化程序存在的危险点及防范措施。     

一类离散SISV传染病模型的理论与仿真分析

引入相应的概率来描述个体的死亡、染病者的恢复、被接种者免疫的失去以及疾病的传染,建立了具有非线性发生率的离散SISV传染病模型.对于总种群动力学性态是补偿的情形,确定了决定其动力学性态的阈值,在阈值之下模型的无病平衡点是局部渐近稳定的,且仿真显示在一些参数取值下模型发生了后向分支,在阈值之上模型是一致持续的;对于总种群动力学性态是过度补偿的情形,仿真显示当总种群动力学性态出现倍周期和混沌现象时,易感类、染病类和被接种类也出现倍周期和混沌现象.