一种基于MVPN的校园网移动应用安全架构模型

由于移动应用与传统的有线网络不同,传统的VPN技术已经不能完全满足移动应用的安全需求。为了更好的解决移动应用的安全问题,本文提出了一种基于MVPN技术的校园网移动应用安全架构模型,并对该模型的应用举例说明。     

电子政务系统体系结构的设计

在分析电子政务的总体技术体系结构模型与应用平台的基础上,介绍了一站式电子政务服务架构的基本设计思路。通过电子政务一站式服务框架的建设,构筑起电子政务整体建设的框架体系结构,统一了标准与平台, 实现了政府、社会和公众之间服务系统的高度整合,为政府构建电子政务系统提供了理论基础和技术支撑。     

齿轮裂纹故障的双谱分析

齿轮振动信号中的非线性给故障特征的提取带来较大难度,通过分析裂纹齿轮振动信号非线性产生的原因,利用双谱分析具有提取信号非线性耦合特征的能力,将双谱分析应用于齿轮裂纹的故障诊断中。试验结果表明,该方法能够有效地将正常及不同裂纹程度的齿轮区分开来。     

基于Android的移动终端GPS测量系统的设计与开发

本文针对手机GPS功能进行移动应用开发,设计并实现了基于Android平台的移动终端GPS测量系统.在分析学生野外测量实习需求的基础上,对系统进行了功能模块划分;在系统的程序模块详细设计中,着重探讨了数据库的设计与地块长度/面积计算方法.测试结果表明,该系统已能替代GPS手持终端,满足野外测量实习的需要.     

非线性刚度碰摩转子系统的分岔与混沌演化

建立一类具有非线性刚度的局部碰摩转子系统模型,用数值积分和Poincaré映射方法研究该系统随不平衡量和刚度比参数变化的分岔与混沌演化过程.通过分岔图、Poincaré映射图揭示该系统存在Neimark-sacker分岔、倍周期分岔、锁相、阵发性切分岔等非线性动力学行为,研究结果揭示碰摩转子系统中一些复杂的非线性现象,为转子系统的故障诊断、振动控制、安全运行及早期预测提供理论参考.     

一种考虑胶瘤的胶接简化有限元模型:应力与刚度分析

胶接接头中总存在胶瘤,由于建模复杂,胶接接头有限元分析中胶瘤常被忽略.但胶瘤能减少峰值应力,提高结构强度和刚度.为此,提出一种简化的胶接有限元模型,即用壳单元代表胶瘤,体单元代表被粘体和胶层,并用弹性理论建立壳单元等效厚度公式.以体单元精细模型结果作为对比的真实解,考察五种载荷工况下,单搭接头简化有限元模型的胶层应力和刚度.分析表明,壳单元等效厚度公式正确,胶接简化有限元模型精度高,可用于诸如汽车等大型结构中;用壳单元简单模型可定量分析胶瘤大小和形状对接头应力和总体刚度性能的影响.     

三嵌段共聚有机硅氧烷的合成与性能研究

以氢氧化锂为引发剂,二甲基甲酰胺为促进剂,采用分步投料法合成出聚二甲基（甲基乙烯基）硅氧烷－聚二甲基二苯基（甲基乙烯基）硅氧烷－聚二甲基（甲基乙烯基）硅氧烷三嵌段共聚物;研究了四甲基四乙烯基环四硅氧烷（D4^Vi)用量对嵌段共聚物的摩尔质量及所制硅橡胶物理机械性能的影响。结果表明,D4^Vi用量对嵌段共聚物的摩尔质量影响不大,但对硅橡胶的物理机械性能影响很大。当D4^Vi质量分数为0.1%、0．2％时,硅橡胶的物理机械性能较好,拉伸强度可达10．70MPa,撕裂强度最大为21．61kN/m,拉伸永久变形为2％－4％。     

Fabricating red-blue-switching dual polymer electrochromic devices using room temperature ionic liquid

In this work, room temperature ionic liquid (RTIL)—1-butyl-3-methyl-imidazolium hexafluorophosphate ([BMIM]PF₆)—was employed to fabricate dual polymer electrochromic devices (DPECDs). [BMIM]PF₆ was used as the electrolyte both in the electrochemical synthesis of conducting polymers (CPs) and in the fabrication of DPECDs. The electrochemically deposited poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3-methylthiophene) (PMeT) were employed to serve as two complementary coloring electrochromic thin films. Through combining these two electrochromic layers, the assembled DPECDs were found to switch between deep red and deep blue, which are two primary colors for a display. By employing RTIL as electrolyte, the devices retained 65% of their optical contrast and electroactivity after 5×10³ deep double potential steps, showing enhanced stability and durability. The DPECDs also exhibited stable electrochromic performance, with a maximum optical contrast of 26% at 665 nm, and achieved a high coloring efficiency of 460 cm² C^-1.     

Theoretical calculation and experimental study of influence of oxygen vacancy on the electronic structure and hemocompatibility of rutile TiO2

In this work, the relationship between electronic structure and hemocompatibility of oxygen deficient rutile TiO_2?x was studied by both theoretical calculation and experimental study. Based on the local density functional theory, first-principals method was performed to calculate the electronic structure of rutile TiO₂ with different oxygen vacancy concentration. In the range of less than 10% of (or equal) physically realistic O vacancy concentration, the band gap of rutile TiO₂ increases with increasing O vacancy concentration, leading the TiO₂ changes from a p-type to an n-type semiconductor. The valance band of TiO₂ is predominated by O 2p orbital, while the conduction band is occupied by Ti 3d orbital for different O vacancy concentration. The O vacancy results in the occupation of electrons at the bottom of conduction band of TiO₂, and the donor density increases with increasing O vacancy concentration. When materials come in contact with blood, the n-type semiconductor feature of oxygen deficient TiO_2?x with the bottom of conduction band occupied by electrons would prevent charge transfer from fibrinogen into the surface of materials, thus inhibiting the aggregation and activation of platelets, therefore improving the hemocompatibility of rutile TiO_2-x .