Investigation of the contribution of radicals to the mechanism of the early stage of the Maillard reaction

Involvement of radical reactions in the mechanism of the Maillard reaction is demonstrated. Intermediate Maillard reaction product interactions with the stable 2,2-diphenyl-1-picryl-hydrazinyl radical, and also electron transfer, followed spectrophotometrically with phenanthrolin, allowed the contribution of these reactions in the Maillard system to be explored. It was, thus, possible to estimate which reaction mechanism (ionic or radical) dominates the early stage of the Maillard reaction, depending on the milieu and the reactants in a model system.The pH value has a significant influence on the participation of radical reactions. Whereas at pH 5 an ionic mechanism seems to be predominant, at increasing pH values reactions proceed with an increasing amount of radical participation. The influence of the amino acids used is marginal, especially at high pH values. In the glycine model, the amount of ionic reactions rises on changing the pH value from 8 to 7.The sugar influence on the reaction mechanism depends particularly on the ability to form sugar fragments and on the molar ratio of sugar to amino acid.     

矸石膏体充填体控制地表沉陷力学性能试验研究

针对膏体充填体在煤矿采空区特殊环境下(高温、高湿、高应力、高密闭)所表现出的力学特性, 运用现场取芯、室内试验等方法开展了矸石膏体充填体力学性能研究, 揭示了充填膏体力学特性(抗拉强度、单轴压缩强度、弹性模量、泊松比)随时间的变化规律, 并运用最小二乘法建立了各力学参数与时间的回归方程。结果表明, 采空区特定的环境条件有助于充填体内部各化学物质的充分反应, 使充填体胶凝性增强, 且充填膏体在承载时抗变形能力强, 能够很好控制地表沉陷。     

风力机叶片气动弹性和颤振主动控制研究进展

文中首先结合国内外研究进展情况概括总结了大型风力机叶片气动弹性等效梁建模理论,以及解决风力机叶片气动弹性稳定性问题的常用方法:BEM方法、动态失速模型和CFD方法.其次,对在现代大型风力机叶片设计中颇受关注的,智能材料在风力机叶片结构颤振及振动主动控制中的应用研究现状也给予了简要的介绍.最后指出一些尚待进一步研究的问题,以及今后的发展方向.     

User interface features influencing overall ease of use and personalization

This study examines user perceptions of gathering information on, locating, and buying compact discs through Web-based interfaces. A group of part-time MBA students in Hong Kong performed a specific set of tasks using the Web sites of two vendors of compact discs. The tasks were selected to be general enough to apply to a variety of on-line shopping situations. As they performed tasks, they answered questions regarding their perceptions of several user interface features as well as their perceptions of overall ease of use. User interface features associated with a perception of overall ease of use were identified, as were differences based on personal characteristics of respondents. Also, differences in perceptions of interface features that might be due to personal characteristics, such as age and sex, were identified. The methodology and results help identify user interface features that a designer should emphasize and features for which personalization is likely to be beneficial.     

基于DSP嵌入式煤矸识别系统的设计

为了提高综采放顶煤工作面自动化水平,提高煤质,介绍一种基于DSP的嵌入式煤矸识别系统,包括整个系统的硬件、软件设计及算法分析。该系统可高速采集振动声波信号,IIR低通滤波去噪后,经过快速傅里叶变换和小波变换对数据进行频谱、功率谱分析,实现煤与矸石的比例识别。CPLD协同DSP实现整个系统的地址译码和逻辑控制,并可以通过RS485/RS232接口实现通信或组网。     

谐波在煤矿选择性漏电保护中的应用研究

目前煤矿供电系统中,适用于中性点经消弧线圈接地的选择性漏电保护较少,针对该现状,文章在研究供电系统谐波理论的基础上,提出了应用五次谐波判断故障线路的理论。通过分析得出,故障线路与非故障线路中五次谐波电流方向相反且幅值最大,该结论可用于选择性漏电保护中。     

基于散度比例准则的高分辨距离像特征提取

针对传统线性判别分析(LDA)的子空间倾向于保留大类间距离类对的可分性,而丢弃小类间距离类对的可分性的问题,基于子空间应均衡保留各类对可分性的思想,提出一种新的准则——散度比例(PD)准则。PD准则为各类对子空间散度与原空间散度之比的均值,并推导出最大化PD准则的线性判别分析(PD-LDA)的求解过程。采用PD-LDA对高分辨距离像(HRRP)的幅度谱进行特征提取,基于外场实测数据,分别训练了最小欧氏距离分类器和支持向量机(SVM)分类器,两种分类器的识别结果均表明,PD-LDA相比LDA,可显著降低数据维数并有效提高识别率。