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英语动词间接时态的运用——对英语非谓语动词的研究 被引量:1
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作者 朱雪萍 《长沙铁道学院学报(社会科学版)》 2006年第3期158-160,共3页
本文根据易仲良教授关于英语动词时态的理论及由此得出的直接时态和间接时态的分类(1999),基于李小川对英语动词间接时态的研究(2002),在易教授英语动词“五、二范畴体系”的框袈中,简析了间接时态的语法范畴体系以及与其它范畴结合的理... 本文根据易仲良教授关于英语动词时态的理论及由此得出的直接时态和间接时态的分类(1999),基于李小川对英语动词间接时态的研究(2002),在易教授英语动词“五、二范畴体系”的框袈中,简析了间接时态的语法范畴体系以及与其它范畴结合的理拒,阐明了间接时态与其它语法范畴结合的语义关系是并列的语义关系,印证了间接时态作为独立的语法范畴体系确立的合理性。 展开更多
关键词 直接时态 间接时态 先时时态 非先时时态 不定时态
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Design of variable structure controller for uncertain time-delay singular system 被引量:1
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作者 郭继峰 高存臣 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2009年第3期331-337,共7页
To study the approximation theory of real sliding mode and the design of variable structure controller for time-invariant linear uncertain time-delay singular system,the approximation theory of real sliding mode was d... To study the approximation theory of real sliding mode and the design of variable structure controller for time-invariant linear uncertain time-delay singular system,the approximation theory of real sliding mode was developed to provide foundation for obtaining sliding mode by equivalent control,and switching functions with integral dynamic compensators and variable structure controllers were designed respectively under two circumstances that the system without uncertain part was stabilized by delay-dependent and delay-independent linear state feedback. The design guarantees the asymptotical stablity of switching manifolds,and the variable structure controllers can force solution trajectory of the system to arrive at the switching manifolds in limited time. A numerical example is given to demonstrate the feasibility and simplicity of the design method. 展开更多
关键词 singular system TIME-DELAY uncertain system variable structure control
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Stabilization of a class of nonlinear discrete time systems with time varying delay
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作者 Maryam Fattahi Nastaran Vasegh Hamid Reza Momeni 《Journal of Central South University》 SCIE EI CAS 2014年第10期3769-3776,共8页
The stability and stabilization of a class of nonlinear discrete time delayed systems(NDTDS) with time-varying delay and norm-bounded nonlinearity are investigated. Based on discrete time Lyapunov–Krasovskii function... The stability and stabilization of a class of nonlinear discrete time delayed systems(NDTDS) with time-varying delay and norm-bounded nonlinearity are investigated. Based on discrete time Lyapunov–Krasovskii functional method, a sufficient delaydependent condition for asymptotic stability of nonlinear systems is offered. Then, this condition is used to design a new efficient delayed state feedback controller(DSFC) for stabilization of such systems. These conditions are in the linear matrix inequality(LMI) framework. Illustrative examples confirm the improvement of the proposed approach over the similar cases. Furthermore, the obtained stability and stabilization conditions will be extended to uncertain discrete time delayed systems(UDTDS) with polytopic parameter uncertainties and also with norm-bounded parameter uncertainties. 展开更多
关键词 nonlinear discrete time delayed systems Lyapunov–Krasovskii functional delayed state feedback linear matrix inequality(LMI) polytopic parameter uncertainties norm bounded parameter uncertainties
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TRAVELING WAVE SOLUTIONS IN A THREE-SPECIES FOOD-CHAIN MODEL WITH DIFFUSION AND DELAYS 被引量:1
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作者 YANKE DU RUI XU 《International Journal of Biomathematics》 2012年第1期17-33,共17页
This paper deals with the existence of traveling wave solutions in a three-species food-chain model with spatial diffusion and time delays due to gestation and negative feedback. By using a cross iteration scheme and ... This paper deals with the existence of traveling wave solutions in a three-species food-chain model with spatial diffusion and time delays due to gestation and negative feedback. By using a cross iteration scheme and Schauder's fixed point theorem, we reduce the existence of traveling wave solutions to the existence of a pair of upper-lower solutions. By constructing a pair of upper-lower solutions, we derive the existence of a traveling wave solution connecting the trivial steady state and the positive steady state. Numerical simulations are carried out to illustrate the main results. In particular, our results extend and improve some known results. 展开更多
关键词 Traveling wave solutions upper-lower solutions partial exponentialquasi-monotonicity Schauder's fixed point theorem food chain.
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