Finite-time adaptive fuzzy control for a class of output constrained nonlinear systems with dead-zone

The article investigates the finite-time adaptive fuzzy control for a class of nonlinear systems with output constraint and input dead-zone. First, by skillfully combining the barrier Lyapunov function, backstepping design method, and finite-time control theory, a novel adaptive state-feedback tracking controller is constructed, and the output constraint of the nonlinear system is not violated. Second, the fuzzy logic system is used to approximate unknown function in the nonlinear system. Third, the finite-time command filter is introduced to avoid the problem of “complexity explosion” caused by repeated differentiations of the virtual control signal in conventional backstepping control schemes. Meanwhile, a new saturation function is added in the compensating signal for filter error to improve control accuracy. Finally, based on Lyapunov stability analysis, all the signals of the closed-loop are proved to be semi-globally uniformly ultimately bounded, and the tracking error converges to a small neighborhood region of the origin in a finite time. A simulation example is presented to demonstrate the effectiveness for the proposed control scheme.     

Preparation of biaxially textured Ce1-x(Y0.2Zr0.8)xOδ buffer layers on RABiTS NiW tapes by chemical solution deposition

Highly (100)-oriented Ce_1-x(Y_0.2Zr_0.8)_xO_δ (CYZO) films were prepared on biaxially textured NiW substrates by a chemical solution deposition approach using metal inorganic salts as starting materials. It has been found that both the preferential orientation and surface roughness of CYZO films decrease gradually with increasing of the doping percentage of Y³⁺ and Zr⁴⁺ ions. The epitaxial growth relationship of (220)_CYZO//(200)_NiW and [00?l]_CYZO//[001]_NiW was demonstrated by XRD texture measurement as well as atomic resolution STEM observation. XRD, Raman and XPS spectra results indicate that Y³⁺ and Zr⁴⁺ ions were indeed introduced into CeO₂ lattice to substitute Ce⁴⁺ ions and form cubic fluorite CYZO solid solution. Moreover, CeO₂ buffer layer can be endowed a strong enough capability to prevent element diffusion through co-doping of yttrium and zirconium, provided that an optimal doping ratio of them is adopted. This will provide a new approach to fabricating strong-barrier single buffer layer for coated conductor.     

浅谈参地开发中水土流失防治对策

本文通过对典型小流域内参地开发造成水土流失的分析,提出适合本区域操作的参地防治对策。     

地震多次波压制方法技术应用研究

辽河盆地西部凹陷地质条件复杂，地震波场中多次波较发育，受其影响，主要目的层反射波干涉现象较严重，有效波难以识别，总体信噪比不高，给构造及岩性解释造成困难。对三维地震资料的处理研究表明，采用预测反褶积、F—K域多次波衰减技术及近道内切法等相结合的方法压制多次波是一种有效的途径。从资料处理效果看，剖面质量明显得到改善，证明该组合去噪技术是切实可行的。     

热声制冷机及其改进实验研究

热声制冷作为一种很有前途的制冷方法，在国内外相关领域引起了极大兴趣。热声制冷机由声发生器、共振管、板叠及高、低温换热器等部分组成。对声驱动器的振动膜及其冷却系统、气体弹簧系统、高、低温换热器进行了初步改进，使制冷机冷端温降从原来的12℃提高到27℃左右，这是目前国内报道的最大温降。     

弹道靶道测量精度检测方法之探讨

该文分析了弹道靶道测量中的精度问题及通常使用的静态检测方法,并针对静态检测与靶道实测相差甚远的问题,提出了一种动态检测方法.该方法充分考虑到弹道靶道的测量对象是高速飞行体以及照片质量、气流附面层、发射时的恶劣环境和振动等因素对测量精度的影响,结合误差理论,给出了动态精度的计算公式,在已建成的IB-12中间弹道靶道中应用,效果良好.     

Coal liquefaction using a hydrogenated creosote oil solvent: H-atom transfer from hydrogen donor components in the solvent

The presence of hydroaromatic, hydrogen donor components in a coal-derived solvent is one of the more important factors in the successful operation of a non-catalytic coal liquefaction process. Various hydrogen donor species present in a hydrogenated creosote oil have been identified. Their rate of disappearance under conditions that are consistent with a short residence time coal liquefaction process has been used to rank the reactivities of the various hydrogen donors. 1,2,3,10b-Tetrahydrofluoranthene was found to be an exceptional donor while 4,5-dihydropyrene, the hexahydropyrenes and 9,10-dihydrophenanthrene were found to be quite active. Sym.-octahydrophenanthrene and 2a,3,4,5-tetrahydroacenaphthene exhibited moderate activity. Tetralin and the four methyltetralin isomers were found to be unreactive under the coal liquefaction conditions employed.