Adaptive tracking control of leader–follower systems with unknown dynamics and partial measurements

In this paper, a decentralized adaptive tracking control is developed for a second-order leader–follower system with unknown dynamics and relative position measurements. Linearly parameterized models are used to describe the unknown dynamics of a self-active leader and all followers. A new distributed system is obtained by using the relative position and velocity measurements as the state variables. By only using the relative position measurements, a dynamic output–feedback tracking control together with decentralized adaptive laws is designed for each follower. At the same time, the stability of the tracking error system and the parameter convergence are analyzed with the help of a common Lyapunov function method. Some simulation results are presented to validate the proposed adaptive tracking control.     

Transformation of Crystal Phase of Micron-sized Rutile TiO2 and Investigation on its Sonocatalytic Activity

The partial transformation of crystal phase of micron-sized TiO₂ powder from rutile to anatase was realized utilizing microwave irradiation in hydrogen peroxide solution. Afterwards, the ultrasound of low power was used as an irradiation source to induce the transition crystal TiO₂ powder to perform the sonocatalytic activity through the degradation of azo fuchsine in aqueous solution. The results show that the sonocatalytic activity of the transition crystal TiO₂ powder is obviously higher than that of pure micron-sized rutile and anatase TiO₂ powders. The degradation ratio of azo fuchsine in the presence of the transition crystal TiO₂ powder attains nearly 80% within 80 min ultrasonic irradiation.     

A new core–shell type fluorinated acrylic and siliconated polyurethane hybrid emulsion

A novel core–shell type fluorinated acrylic and siliconated polyurethane (FSiPUA) hybrid emulsion was prepared by seeded emulsion polymerization using siliconated polyurethane (SiPU) as a seed and forming the structure with SiPU as a shell and the copolymer of butyl acrylate (BA) with 2,2,2-trifluoroethylmethacrylate (TFEMA) as a core. SiPU was synthesized using isophorone diisocyanate (IPDI), polytetramethylene ether glycol (PTMG), polypropylene glycol (PPG), dihydroxybutyl-terminated polydimethylsiloxane (PDMS), dimethylol propionic acid (DMPA), 1,6-hexanediol (HDO) and triethylamine (TEA). The contents of siloxane and fluorine were determined according to the feed ratio. Fourier transform infrared spectroscopy (FTIR) was used to identify the chain structure of SiPU and FSiPUA. Investigation of transmission electron microscopy (TEM) confirmed the core–shell structure of FSiPUA emulsion and gave the particle size at about 50 nm. The measurement results of water contact angles and the solvent absorptions in water and n-octane for cured films showed that the water and the oil repellency for FSiPUA had been improved significantly with a suitable content of fluorine and siloxane.     

改性淀粉与丙烯酸接枝共聚物的合成及应用性能

研究经过热处理的改性淀粉与丙烯酸的接枝共聚反应。接枝共聚产物在 790cm-1、85 0cm-1(物理改性淀粉的特征吸收峰 )和 172 0cm-1(聚丙烯酸的特征吸收峰 )处的红外光谱验证了接枝共聚反应的发生。探讨了引发剂过硫酸铵浓度、丙烯酸浓度、反应温度和反应时间等因素对接枝率和接枝效率的影响。当 ρ(淀粉 ) =70 g/L、t =6 0℃、反应时间为 3h、c〔(NH4) 2 S2 O8〕 =3 0× 10 -3 mol/L、c(丙烯酸 ) =0 4 2mol/L时 ,合成胶粘剂的初粘力为 10 0 % ,吸水率为 15 0 14 % ,吸油率为 2 0 6 % ,其压制的纸板冲击强度为 3 2 5kN/m ,拉伸强度为 3 75MPa ,与纯淀粉粘接剂相比较 ,所压制纸板的应用性能得到较大的改善。     

扎实推进规划工作 培植绿色发展理念——湖北省中小河流水能资源开发规划工作情况介绍

本文介绍了湖北省中小河流水能资源开发规划工作进展,规划工作在树立绿色发展理念、摸清水能资源开发状况等方面取得的成效,以及湖北省为推动规划工作采取的主要做法。     

骨组织工程支架材料

寻找理想的支架材料是目前骨组织工程研究的热点。本文对用于骨组织工程支架材抖的天然生物衍生材料、聚合物类材料、陶瓷材料及其复合材料等的研究现状进行综述，分析了这些材料的优缺点，并对骨组织工程支架材料发展趋势进行了展望。     

核苷酸生产技术现状及展望

核苷酸的生产方法主要有化学合成法、RNA酶解法、微生物发酵法以及生物催化法。探讨了这些方法的原理和发展及其在工业化生产中的优劣势。化学合成法的路线长、立体选择性差,所用试剂昂贵并有一定毒性,生产成本较高;酶解法能一次得到4种核苷酸的混合物且收率较高,是目前我国核苷酸工业生产所用的主要技术,但其后提取难度大,产品纯度不高;微生物发酵法难以解决细胞通透性的问题;生物催化法是发酵法的延伸,菌体培养和酶催化反应分两步进行,有效地解决了细胞通透性问题,并可以通过偶联不同的基因工程菌株生产多种复杂核苷酸、核苷糖乃至寡聚糖,这在核苷酸工业、医药及糖化学、糖生物学合成工业中是极其重要的一个环节。     

膜生物反应器技术处理洗浴废水的工程应用

根据洗浴废水的水质水量，设计了生物接触氧化和膜生物反应器相结合的处理工艺(水量为120m^3／d)。通过对工艺相关设计参数的选取和调试运行结果表明，该工艺具有处理效果稳定、抗冲击负荷强以及操作简便等优点。     

过硼酸钠在有机合成中新的应用

介绍了过硼酸钠在有机合成中的一些新的应用。综述了过硼酸钠与芳胺、芳酰胺、有机硼化物、醛等化合物的氧化,取代、酯化反应。     

密度泛函方法的ZSM-5分子筛上苯与乙烯烷基化反应机理研究

采用密度泛函(DFT)方法对于ZSM-5分子筛上苯与乙烯的烷基化反应机理进行研究。选取了包含酸性质子的8T原子簇模型代表ZSM-5分子筛的部分结构。采用B3LYP/6-31G(d)水平从生成能与反应活化能角度对于烷基化反应发生时可能存在的2种联合机理和一种分步机理进行了计算与比较。结果表明,联合反应机理中乙烯的质子化和C-C键的形成同时发生,而分步机理开始于乙醇盐中间体的生成,随后与苯反应生成反应产物。分步机理中乙醇盐中间体生成步骤的活化能(124.55 kJ/mol)低于联合机理的反应活化能(168.98 kJ/mol和156.06 kJ/mol),而烷基化步骤的活化能(209.35 kJ/mol)高于联合机理的反应活化能,由此可以推断ZSM-5分子筛上苯与乙烯的烷基化反应时2种机理同时发生,存在竞争关系。