纳米二氧化硅模板的制备

以微乳液法制备纳米二氧化硅（SiO2）粒子，经压制、烧结制备SiO2模板。通过红外（IR）、热分析（TGDTA）、扫描电镜（SEM）等方法对SiO2模板进行表征，结果表明所得SiO2粒度在100nm左右．烧结温度在800℃时，SiO2粒子之间将实现颈长，有利于有机／无机杂化多孔材料的制备。     

光活性二氧化钛涂层的研究与制备

本文介绍了制备光活性TiO2涂层的两种主要方法，并就一些影响因素进行了简单的讨论。     

轻量级PRESENT加密算法功耗攻击研究

PRESENT密码算法是2007年提出来的一种轻量级分组密码算法, 适合于物联网环境下的安全加密。对PRESENT加密算法结构进行了深入研究, 提出了其适合功耗攻击的两个最佳攻击点, 详细介绍了针对PRESENT加密系统进行功耗分析攻击的设计与实现过程, 实验结果表明未加防护措施的PRESENT加密系统不能抵御一阶差分功耗分析攻击, 从而给PRESENT加密算法的安全改进提供一定的设计参考。     

AES加密算法面积与性能平衡优化研究

AES密码是目前主流应用的加密算法,研究了在面积优化的同时兼顾加密速度的解决方法.根据字节代换的要求和特点,S盒变换采用16×16位的空间预存储置换表,通过O(1)查表效率即可实现SubBytes变换.将伽罗华域上所有元素的两倍先存储在一张表格中,相应运算只需要通过查表和相加就可以完成,避免了有限域的乘法运算,有效减少了运算次数.密钥扩展是独立于加密算法本身的一个特殊模块,采用上升沿有效的时钟控制密钥生成方法,在生成密钥的同一个时钟周期下降沿进行密钥传递,减少了系统延时,增强了并行性,使得面积优化后的AES加密效率更高,吞吐量更大.通过计数器控制加密函数调用的轮数,使得每个模块能多次被调用,从而使得加密芯片面积减少.实验表明在Xilinx Virtex-5 FPGA上优化后的加密模块所占用面积为11 163 Slices,相比优化之前的20 173 Slices,占用面积减少了将近一半.     

Effect of test frequency and water content on localized crack-tip heating in nylon-6,6

Fatigue crack propagation (FCP) tests were conducted at various frequencies on nylon-6,6 specimens equilibrated over a range of moisture levels to determine the crack growth rates and the crack-tip temperatures as a function of water content. Frequency-sensitivity was correlated with the amount of crack-tip heating taking place, with crack-tip temperature being found to depend strongly on the estimated loss compliance, D″, of the material. The frequency-sensitivity of FCP in nylon was seen also to be affected by mean stress, suggesting that creep processes are often significant in FCP of nylon.     

基于DSP的前方车辆位置关系辨识研究

为提高前方车辆位置关系辨识效能,提出利用基于统计特性的图像识别算法辨识前方车辆位置关系。通过车载CCD实时获取道路图像信息,使用最小二乘法进行车道线拟合,结合道路图像同侧上、下车道标识线的斜率关系判定道路线形,以车道中线标定前方车辆位置;基于图像统计特性进行前方车辆识别,计算车辆标识点至车道中线的距离,通过与设定的阈值进行比较来确定前方车辆与自车的位置关系。实验结果表明,该算法能够有效降低由树阴和路面油污对辨识所造成的影响,抗干扰能力强,对不同曲率的道路具有良好的适应性。     

不饱和酸结构对不饱和聚酯树脂固化行为的影响

通过IR分析了用顺酐和反酸与聚酯合成不饱和聚酯树脂的反应机理,讨论了二种树脂体系固化放热曲线不同的原因。     

A parametric frequency response method for non-linear time-varying systems

A new parametric frequency response algorithm is introduced to investigate linear and non-linear dynamic systems with time-varying parameters. In the new algorithm the time-varying parameters are regarded as additional inputs of the systems and the non-linear generalised frequency response functions for multi-input-single-output systems are then employed to obtain Zadeh's system functions from a differential equation representation. The parametric frequency response method reveals how the time-varying parameters affect the behaviour of the systems through a time-varying term. The new method can be applied to both linear and non-linear time-varying systems.     

Removal of formaldehyde at low concentration using various activated carbon fibers

Adsorption of low concentration formaldehyde on pitch‐based, rayon‐based, and PAN‐based activated carbon fibers (ACFs) and an unactivated PAN‐based carbon fiber (PAN‐CF) was investigated by a dynamic method. The pore structure and surface chemistry of these samples were characterized by liquid nitrogen adsorption, elemental analysis, and X‐ray photoelectron spectroscopy. Results revealed that the pore structure, especially surface chemical composition, greatly influence the formaldehyde adsorption. PAN‐based ACFs showed the highest formaldehyde adsorption capacity because there are more abundant nitrogen‐containing groups, especially pyrrolic, pyridonic, pyridinic, and quaternary on the surface. The breakthrough time and formaldehyde adsorption capacity of one kind of PAN‐ACF were 361 min and 0.478 mmol/g, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

基于三电平逆变的开关磁阻发电系统的研究

新型开关磁阻发电机具有发电容量大、效率高、起动和发电组合容易等优点,三电平逆变器具有能减少开关损耗和滤波电感损耗并有降低开关应力等特点。利用三电平逆变器转换效率高的优势,结合新型开关磁阻发电机低风速发电特点,降低开关损耗和开关器件电压应力,提高装置可靠性。仿真实验结果表明:用三电平逆变器能够很好的实现开关磁阻发电机的逆变要求。