Two-step anodization of maltilayer TiO2 nanotube and its photocatalytic activity under UV light

A double-layer TiO2 nanotube arrays were formed by two-step anodization of Ti foils in different electrolytes. First, Ti in 0.5 wt% HF was anodized to form thin nanotube layer. Afterwards a second anodization was conducted in a formamide based electrolyte, which allowed the second layer of nanotube growing directly underneath the first one. From FESEM investigation we found that the thickness of second layer corresponded to the anodization time, the increasing of which would lead to the excessive etching on the first layer. The first layer protected the lower one from fluoride corrosion during anodization process. The double layer TiO2 nanotube arrays showed no benefit to photodegradation effect in methyl orange degradation experiments.     

基于时域Neal-Smith准则的人机控制系统设计多目标优化研究

为了获得驾驶员和飞机良好的匹配特性,使用基于人机闭环参考模型的方法将飞行品质的要求引入优化算法,进行飞行控制系统设计。首先使用CAP准则建立飞机等效系统模型。然后,基于时域Neal-Smith准则,通过多目标优化算法一次性得到在不同任务条件下的最优驾驶员模型。根据需要选择相应的驾驶员模型,并与飞机等效系统模型组成人机闭环参考模型,进行飞行控制设计多目标优化。仿真结果显示,文中的算法不仅可以整定控制器参数,根据任务需求选取最优驾驶员模型,还可以利用优化结果进行PIO易感性的分析。     

Locally Limited and Fully Conserved RKDG2 Shallow Water Solutions with Wetting and Drying

This work extends a well-balanced second-order Runge-Kutta discontinuous Galerkin (RKDG2) scheme to provide conservative simulations for shallow flows involving wetting and drying over irregular topographies with friction effects. For this purpose, a wetting and drying technique designed originally for a finite volume (FV) scheme is improved and implemented, which includes the discretization of friction source terms via a splitting implicit integration approach. Another focus of this work is to design a fully conserved RKDG2 scheme to provide conservative solutions for both mass and momentum through a local slope limiting process. Several steady and transient benchmark tests with/without friction effects are simulated to validate the new solver and demonstrate the effects of different slope limiting processes, i.e. globally and locally slope limiting processes.     

Operation speed limited by the electric properties of?the?photorefractive spatial light modulator

With excellent photo-electric and electro-optical effects, the photorefractive spatial light modulators can work as optically addressed modulators in optical information processing systems and parallel optical computing systems. The photo-induced current pulses of the photorefractive spatial light modulator observed in the experiments are analyzed to conclude the characteristics, and to find the relationship between the properties of the current pulse and the structural parameters. Furthermore, the origin of the photo-induced current pulse is analyzed, and the methods to improve the operation speed of the spatial light modulators are proposed. The research results will be significant for extending the applications of the photorefractive spatial light modulators, and pushing ahead the research of all-optical modulation materials and devices for optical supercomputing.     

地震勘探技术在解释地质异常体的应用分析

地震勘探技术在控制煤层赋存形态方面有高于其它物探方法的优势,尤其在准确圈定小窑采空区、岩浆岩侵蚀、煤层露头、火烧区及冲刷带、陷落柱等地质异常体方面已取得了很好的效果,对煤矿产业的生产和建设都起到了举足轻重的作用。本文通过河北、新疆和山西等地煤矿采区三维地震勘探实例介绍了如何根据地震时间剖面表现的不同特征来确定和解释各种煤层地质异常体,并取得了良好的地质成果。     

Study on Wheel and Workpiece Position Error Influence on Surface Shape Accuracy during Ceramic Ball Grinding

The reasons for bringing surface accuracy error in uhra-precision grinding ceramic ball joint were analyzed, and the influences wheel position error and shaft run-out error on the ball joint surface accuracy were discussed. Through establishing three-dimensional grinding model, the mathematical relationship between the position error and surface accuracy was derived, and the distance from any point on spherical surface to the ideal center was calculated when position error existed, and a precise surface shape was got, and theoretical support was provided to improve the surface accuracy during the grinding process. Using self-developed ultra- precision grinding machine to do the ceramic ball grinding experiment, the surface accuracy PV value of ceramic spherical joint is 4. 8 μm.     

改进的无限折叠混沌映射伪随机数发生器

分析了某种新型均匀分布伪随机数发生器对初始值要求严格的主要原因,并通过引入Logistic混沌映射,提出了能够消除不良初始值的改进伪随机数发生器.计算机仿真结果表明,该方法产生的均匀分布伪随机教对初始值选择无特殊要求,而且具有良好的统计性能.     

基于嵌入式系统开发平台的设计与实现

本文首先介绍了EVB2107评估板、评估板的系统开发工具和集成开发环境,然后对扩展板上各模块都从原理入手结合该模块要实现的功能说明其设计思想和实现原理,并就各模块驱动程序的编程思想及流程进行了论述。     

校园网病毒的入侵途径和防毒策略

本文从校园网病毒的入侵途径入手,对校园网的安全管理发表见解,重点对网络病毒的防御策略进行了介绍,给读者提供了一些有参考价值的策略,以保障校园网的安全运行。     

Preparation, optical properties and cell staining of water soluble amine-terminated PAMAM G 2.0-Au nanocomposites

The solution chemical and optical characteristics of formation of amine-terminated polyamidoamine dendrimer G2.0(NH₂-PAMAM G2.0)-Au nanocomposites in the aqueous solution of NH₂-PAMAM G2.0 at various mole ratios of Au(III) to NH₂-PAMAM G2.0 were studied by both UV-visible spectrometry and fluorospectrometry. The NH₂-PAMAM G2.0-Au nanocomposites, with a type of structure in which one Au nanoparticle is surrounded by several NH₂-PAMAM G2.0 dendrimers, emit strong bluish violet fluorescence, and are uniform, water soluble and biocompatible as well as very stable in frozen conditions. The size of gold nanoparticles in the nanocomposites is about 2.5 nm and decreases with the increase of NH₂-PAMAM G2.0 concentration. The NH₂-PAMAM G2. 0 plays an important role in acting as host or micro-reactor for Au(III) before Au(III) reduction and acting as dispersant and stabilizer for gold nanoparticles after Au(III) reduction. Preliminary experiments of cells staining to human embryonic lung fibroblast cell lines show that the NH₂-PAMAM G2.0-Au nanocomposites can be used as optical imaging markers for bioanalyses and medical diagnoses.