移动IPv6安全绑定更新机制研究

介绍了移动IPv6网络中节点移动后进行三角路由优化所引出的绑定更新安全问题,阐述了在非PKI体系中解决绑定更新安全隐患的几种机制;在阐述的同时对这些机制进行了安全性分析,最后对这几种机制从安全性角度进行比较.     

湿法磷酸生产中管道结垢物二氧化硅含量的测定

介绍采用氟硅酸钾容量法测定湿法磷酸生产中管道结垢物二氧化硅含量的方法及注意事项。该法较常用的高氯酸脱水重量法操作简单、快速,具有较好的准确度。     

FY-2C卫星太阳电池阵在轨性能分析

风云二号气象卫星(C星)在轨工作近六年,该卫星电源系统采用BSFR太阳电池阵,这是空间电源工程首次在地球静止轨道上应用。母线电流遥测数据分析表明,太阳电池阵在同步轨道四年衰降约11%。     

2^N-1级联式30电平逆变器

本文介绍了一种新型的2^N-1级联式30电平逆变器的基本工作原理和控制方法。     

一种基于软阈值方法的改进A1/A2极化干涉分类算法

在分析了极化干涉技术的发展现状和发展趋势的基础上,从极化干涉的特殊性入手,分析了干涉相干系数在极化干涉分类中的作用,并且系统分析了基于相干最优优化后的相干系数进行极化干涉分类过程的原理,总结了现有极化干涉分类算法在阈值选择方面存在的不足,阐述了硬阈值方法和软阈值方法的基本原理和它们之间的区别,最后提出基于软阈值方法的改进A1/A2非监督极化干涉分类算法,解决了极化干涉分类现有的分类空间中的阈值问题。实验表明这种方法能够得到更好的分类结果,做出了改进。     

饱水石灰岩骨架和流体弹性参数的估算

本文利用Niu等提出的基于临界孔隙度模型的组分弹性参数数值计算方法,把测试岩石样品的孔隙度、整体密度、纵波速度和横波速度作为数值计算的输入数据,运用双线性数值计算方法反演求出临界点、流体和骨架的12个弹性参数。具体做法是:基于临界孔隙度模型,给出三组线性关系,即密度—孔隙度,整体剪切模量—孔隙度,整体纵波模量—孔隙度,上述每组线性关系分别以孔隙度作为自变量和因变量得到两个线性方程,再把两个方程计算的结果进行加权平均得到相关的弹性参数估算值,并结合饱水石灰岩样品数据实现了弹性参数估算。数值计算结果表明,由数值计算得到的弹性参数与测试弹性参数的均值和方差相差甚微,特别是密度数据的偏差均值更小,说明文中的数值计算结果是可靠的。     

金属切削液在轴承加工中的应用

着重介绍金属切削液的分类、功能及其在轴承加工中的选用。在轴承加工中,一般有车削、铣削、钻削、铰削和磨削等多种加工工艺,其中磨削加工是一道非常重要的精密加工工序,如内圆磨削、外圆磨削、平面磨削和沟槽磨削等。轴承加工中使用的水基切削液不仅要具有冷却作用,还要有润滑、清洗和防锈的功能。重点介绍金属切削液的主要功能及其在轴承加工中的应用。     

Sol-gel assisted preparation and characterization of silver indium diselenide powders

AgInSe₂ powders were successfully prepared via mixing sol-gel derived precursors, followed by a selenization process. To obtain the pure AgInSe₂ compound, excess amounts of In³⁺ ions were added into the starting solution to compensate the loss of In₂O₃ during the selenization process. A figure that depicts the relationship between the resultant compounds and different selenization temperatures was constructed according to the formed phases. The Raman spectrum and Rietveld refinement confirmed that the prepared AgInSe₂ belonged to the chalcopyrite structure. With increasing selenization temperatures, the AgInSe₂ powder particle sizes as well as the crystallinity increased significantly. The AgInSe₂ formation mechanism during the selenization process is proposed as a two-step process. Ag₂Se is formed in the first step and then induces the second-step reaction to produce AgInSe₂. The sol-gel route with a selenization process is introduced as a new approach to fabricate pure AgInSe₂ powders for use in thin-film solar cells.     

Study on Thermal Deformation Behavior and Properties of Vacuum Hot-press Sintered W(50)/Cu-Al_2O_3 Composite

In this work, the tungsten particulate reinforced Al2O3 dispersion strengthened copper base composites were successfully fabricated by using a vacuum hot-press sintering method. With the test temperature varying from 650 to 950 ℃ and the strain rate varying from 0.01 to 5 s-1, the W(50)/Cu-Al2O3 composites were isothermally compressed on a Gleeble-1500D thermal simulator. The true stress-strain curves of the W(50)/Cu-Al2O3 under different test conditions were obtained. The dynamic recrystallization of the W...