确定性系统一步超前控制算法的探讨

确定性动态系统可以用多种方式进行描述和建模。本文首先探讨了用一种自回归滑动平均模型来描述确定性系统的方法及意义,并在此模型的基础上,引出了适合此种模型的一种最小预测误差控制算法——一步超前控制。并以典型的伺服系统为例,进行了仿真研究及参数、性能分析。     

Non-isothermal kinetics of styrene-butadiene-styrene asphalt combustion

The combustion characteristics of styrene-butadiene-styrene （SBS） asphalt are studied by thermogravimetric analysis （TG/DTG） at four different heating rates. According to the saturates/aromatics/resins/asphaltenes （SARA） fractionation method, the combustion process of SBS asphalt can be divided by Gaussian peak fitting into three main stages： oil content release, resin pyrolysis, and asphaltene and char combustion. When the heating rate increases, the mass losses of the oil content and resin pyrolysis increase, and less asphaltenes are formed at a higher temperature. The activation energy values are calculated by the Coats-Redfern method to be in the range 61.6 kJ/mol-142.9 kJ/mol. The Popescu method is used for the kinetic analysis, and the result shows that the three stages of asphalt combustion can be explained by the sphere phase boundary reaction model, the second order chemical reaction model, nucleation, and its subsequent growth model, respectively.     

近红外漫反射光谱法快速检测苯磺酸氨氯地平片辅料含量

将近红外光谱技术和化学计量学相结合快速检测苯磺酸氨氯地平片辅料含量.通过随机青蛙法、变量投影重要性和竞争自适应重加权采样筛选特征波长变量点,采用9种光谱预处理方法对原始光谱进行处理后,分别建立了偏最小二乘法模型和支持向量回归分析模型,并将这两种模型进行了比较.应用优选模型对样品进行了测试,结果表明:对于所涉及的样本,在最优特征波长变量选择上,随机青蛙法效果较好;在模型预测结果上,与支持向量回归分析模型相比,5个指标的偏最小二乘法定量模型的决定系数,预测均方根误差评价参数效果较好,相对分析误差值均大于3.0.样品测试值与实测值标准误差均小于1.30,配对t检验表明,在a=0.05显著性水平上,两者无显著性差异.因此,可采用近红外漫反射光谱法用于苯磺酸氨氯地平片辅料含量的快速检测,该方法重复性、中间精密度、线性、精确性良好,且可为其他药用辅料含量快速检测提供借鉴.     

Influence of limestone fillers on combustion characteristics of asphalt mortar for pavements

Asphalt materials will be ignited and release significant toxic fumes within tunnel fires. Thus, combustion character- istics of asphalt materials used in road tunnel should be studied in order to limit such an adverse effect. In the present work we study the influence of limestone fillers on combustion characteristics of asphalt mortar by thermogravimetric and kinetic analysis. It is shown that the combustion of asphalt mortar is not just a linear superposition of asphalt and limestone. The limestone will increase the ignition point and the activation energy of the primary volatile release, and will catalyze the char formation from the primary volatile release. Kinetic analysis shows that the primary volatile release stage of asphalt mortar combustion can be explained by a three-dimensional diffusion model, the secondary volatile release and char combustion stage can be explained by a model under the assumption of random nucleation and nuclei growth, whereas the limestone decomposition stage appears to follow the one-dimensional phase boundary model.