A modified adaptive backstepping method for shaft deflection tracking control of magnetically suspended momentum wheel with nonlinear magnetic torque

A modified adaptive backstepping tracking method is proposed to improve the tracking performance of the magnetic bearing system with nonlinear magnetic toque. For a magnetically suspended momentum wheel, two dimensional gyroscopic torque can be produced when the rotor shaft is actively deflected by the active magnetic bearing. High precision rapid tracking control of shaft deflection is desiderated to provide high precision and wide bandwidth outputting torque. The nonlinearity of magnetic bearing is analyzed initially, and the stiffness coefficients of magnetic bearing can be treated as bounded continuous functions with respect to deflection angles. A fuzzy function based adaptive law is proposed to estimate the stiffness coefficients. Combining with a modified backstepping method, the proposed control strategy can deal with the nonlinearity efficiently when the shaft deflects rapidly, and its stability is proved by Lyapunov stability theory. To validate the effectiveness of this method, numerous simulations are performed and the results indicate that this method improves the tracking precision when tracking high frequency reference deflection angles.     

英国和澳大利亚的消防经验及其对我国的启示

由于各国的具体地理、社会等条件存在差异,各国的消防各有优势和特色。在森林火灾的消防工作方面,英国和澳大利亚具有明显优势。作为一个拥有技术开发和创新传统的英国,在消防科学研究,尤其是新技术的研究和消防技术的标准化的上,走在了前面。由于发达国家走过类似发展中国家的道路,有过类似的迅速城市化和工业化的特征,因此这些国家的一些技术和消防经验,对发展我国的消防技术而言是宝贵的财富。     

应用倾角传感器实现对提升机天轮偏摆的检测

本作品拟采用倾角传感器设计提升机天轮偏摆检测装置,旨在利用先进的电工电子技术实现对系统进行改造升级,为矿井生产保障安全。所用的倾角传感器成本低廉、耗能极低,配以电池可以长期工作,将其粘于天轮上,可实时获得偏摆量,并不断地把数据传回地面,在发生危险时再利用报警电路使人员可以及时作出反应,断开电源,排除故障。     

Structural evolution of protein-biofilms: Simulations and experiments

The control of biofilm formation is a challenging goal that has not been reached yet in many aspects. One unsolved question is the role of van der Waals forces and another is the importance of mutual interactions between the adsorbing and the adsorbed biomolecules ("critical crowding"). In this study, a combined experimental and theoretical approach is presented, which fundamentally probes both aspects. On three model proteins-lysozyme, α-amylase, and bovine serum albumin-the adsorption kinetics is studied experimentally. Composite substrates are used enabling a separation of the short- and the long-range forces. Although usually neglected, experimental evidence is given for the influence of van der Waals forces on the protein adsorption as revealed by in situ ellipsometry. The three proteins were chosen for their different conformational stabilities in order to investigate the influence of conformational changes on the adsorption kinetics. Monte Carlo simulations are used to develop a model for these experimental results by assuming an internal degree of freedom to represent conformational changes. The simulations also provide data on the distribution of adsorption sites. By in situ atomic force microscopy we can also test this distribution experimentally, which opens the possibility to, e.g., investigate the interactions between adsorbed proteins.