Synthesis and characterization of titanium doped sodium beta″-alumina

High dense Na-β″-Al₂O₃ electrolyte materials have been synthesized by solid state reaction with boehmite, magnesia, sodium carbonate and titania as the starting materials. The effects of TiO₂ doping percentage on the properties and microstructures of the prepared samples were investigated by X-ray diffraction (XRD), scan electron microscope (SEM), three point bending and ionic conductivity tests. The results indicated that both the relative densities and the phase purities of the samples could effectively improved after doping with TiO₂. The proper doping amount of TiO₂ was to form the transient liquid phase during the sintering process, which would reduce the steric effect and accelerate the diffusivity. Moreover, the mechanical performance of the obtained sample increased to the value above 280 MPa as the doping amount of TiO₂ was larger than 1 wt%. As to the electric properties, if the doping amount was less than 1 wt%, the grain boundary resistivity reduced as the density increased, so the ionic conductivity of the Na-β″-Al₂O₃ was enhanced obviously. However, when the doping amount was above 1 wt%, the ionic conductivity was deteriorated because of the increased resistivity caused by the broadening grain size.     

Biodegradable synthetic polymers: Preparation, functionalization and biomedical application

Biodegradable polymers have been widely used and have greatly promoted the development of biomedical fields because of their biocompatibility and biodegradability. The development of biotechnology and medical technology has set higher requirements for biomedical materials. Novel biodegradable polymers with specific properties are in great demand. Biodegradable polymers can be classified as natural or synthetic polymers according to the source. Synthetic biodegradable polymers have found more versatile and diverse biomedical applications owing to their tailorable designs or modifications. This review presents a comprehensive introduction to various types of synthetic biodegradable polymers with reactive groups and bioactive groups, and further describes their structure, preparation procedures and properties. The focus is on advances in the past decade in functionalization and responsive strategies of biodegradable polymers and their biomedical applications. The possible future developments of the materials are also discussed.     

实现非单调关联故障树PIS的联合技术

采用“非正规”二元决策图（BDD）技术获取最小形割集 (MCS)可能存在掩盖非单调底事件作用的弊端”。以“继承”关键技术为基础,提出了用统一编码的“正规”BDD技术来获取非单调关联故障树的MCS。结合Q-M算法,研究了联合获取非单调关联故障树的质蕴涵集(PIS)的完整过程。实际例证表明,所述方法不但能够准确地析出非单调关联故障树的MCS,而且能够自动地获取其PIS。     

Two-Level Multiple-Output Logic Minimization Using A Single Function

A new method for obtaining a two-level collective minimal cover for a set of incompletely-specified switching functions $S={f_1,f_2,ldots,f_n}$ is presented. The method relies on the introduction of a single auxiliary function F whose subfunctions (restrictions) with respect to some additional auxiliary variables $y_1,y_2,ldots,y_{n-1}$ are certain members of S . The complete sum of F has full information on the multiple-output prime implicants (MOPIs) of the set of functions S . A particularly constrained minimal cover for F contains only labeled versions of some paramount prime implicants (PPIs) of S and can be used to construct a multiple-output minimal cover for S . The present method can proceed by map, algebraic or tabular techniques, though only the map version is presented herein. This version employs a single map whose construction avoids the ANDing operations needed in the classical method, and whose size is almost one half the total size of the maps used by the classical method, and whose entries can be variable as well as constant. The minimization process is a direct two-step technique that avoids constructing the set of all PPIs as it produces only these PPIs needed in the minimal cover. Details of the method are carefully explained and illustrated via a typical example.     

基于Vega Prime的灭火飞机投水特效模拟

为了模拟某型灭火飞机的投水特效,主要研究了基于粒子系统的投水特效.首先阐述了Vega Prime特殊效果模块中粒子系统的基本原理,然后采用面向视点的多边形来表示水粒子,通过具体设置粒子系统中粒子的颜色、透明度、大小、纹理、速度和位置等属性,逼真的模拟了飞机的投水特效.在模拟的过程中,将环境影响因素考虑进去,使用Vega Prime的API函数实现投水特效的实时性,同时将飞机坐标系中的速度转换到渲染的场景坐标系中,实现了投水特效随着飞机运动的效果.实践证明,使用粒子系统模拟飞机的投水特效,使三维真实感更强.     

基于VegaPrime的潜望镜视景仿真系统的实现

虚拟仿真训练已成为军事训练的重要手段之一.为了改变潜望镜过去单一的机械设备操作训练方式,直观形象地显示训练过程,设计了视景仿真系统,用于潜艇攻防训练.采用Vega Prime和Creator,结合GL Studio建立了实时视景仿真的分布式体系结构.对视景仿真系统中场景建模、目标运动控制、人机交互、光学效果、场景特效等关键问题进行了阐述.经过试验,所开发的视景仿真系统具有良好的视觉沉浸感.     

基于Vega Prime的高空飞艇视景仿真设计

针对高空飞艇在飞行控制半物理仿真实验中实时数据可视化的问题,基于虚拟仿真技术,提出了一种高空飞艇视景仿真系统设计方案。建立了高空飞艇三维模型,并使用细节层次等高级建模技术对三维模型数据库进行了优化。提出了通过反射内存网与半物理仿真系统进行实时数据传输的方式,在Vega Prime环境下完成了基于控制台的视景仿真程序开发。在硬件系统支持下,实现了高空飞艇飞行过程仿真场景的立体渲染,仿真效果能够满足半物理仿真实验数据的实时逼真显示要求。     

基于Vega Prime三维场景大地形的实时仿真

从战场作战模拟出发,利用专业地形制作软件CTS(Mulitigen Creator Terrain Studio)生成大地形,分析大地形数据组织调用原理,并通过Vega Prime API实现虚拟战场场景的管理和调度。     

螺杆钻具的应用现状及发展方向

对目前国内外螺杆钻具的发展现状进行了系统调研,并对现场使用中的几个实际问题,例如正确掌握钻具的制动扭矩、钻头水眼压降与钻压的合理匹配以及旁通阀在运转中容易出现的几个问题等都进行了较深入的表述和分析。最后对螺杆钻具目前国内外在工艺技术方面发展的新动向以及今后在使用上应用该解决的问题提出了有益的建议。     

关于一类整函数的素性

证明如下定理:设F′(z)=P(z)exp(P1(z)exp(P2(z)) P3(z)),其中P(z),P1(z)及P3(z)都是非零多项式,P2(z)是非常数多项式,P1(z),P2(z)及P3(z)没有非线性右因子。若deg(P2(z))≠deg(P1(z)),则F(z)是素的。