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基于混凝土构件的声发射源时域丛集特性的理论研究
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作者 吴彩星 穆江飞 严超群 《地下水》 2023年第4期149-151,共3页
与地震产生机制相似,声发射源在时间及空间上也具有丛集特性。为探究声发射源在时域上丛集特性的研究方法,现从定性和定量两个角度,对声发射源丛集特性的表征方法进行探究,并对声发射源的丛集特性进行验证。理论研究表明:丛集特性主要... 与地震产生机制相似,声发射源在时间及空间上也具有丛集特性。为探究声发射源在时域上丛集特性的研究方法,现从定性和定量两个角度,对声发射源丛集特性的表征方法进行探究,并对声发射源的丛集特性进行验证。理论研究表明:丛集特性主要表现为事件分布的不均匀,在定性方面,用混凝土构件在受力作用下同时长内产生的声发射事件的频数对声发射源时域丛集特性进行定性分析;在定量方面,用时间离散系数对声发射源时域丛集特性进行定量刻画。 展开更多
关键词 混凝土构件 声发射事件 丛集特性 频数 时间离散系数
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Exponential stability for networked control systems based on the model of nonlinear discrete-time system with time-varying delay 被引量:1
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作者 HUANGJian GUANZhihong WANGZhongdong 《Journal of Chongqing University》 CAS 2004年第1期30-33,共4页
An uncertain nonlinear discrete-time system model with time-varying input delays for networked control systems (NCSs) is presented. The problem of exponential stability for the system is considered and some new criter... An uncertain nonlinear discrete-time system model with time-varying input delays for networked control systems (NCSs) is presented. The problem of exponential stability for the system is considered and some new criteria of exponential stability are obtained based on norm inequality methods. A numerical example is given todemonstrate that those criteria are useful to analyzing the stability of nonlinear NCSs. 展开更多
关键词 networked control systems nonlinear discrete-time system time-varying delay exponential stability
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Multi-objective robust controller synthesis for discrete-time systems with convex polytopic uncertain domain
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作者 张彦虎 颜文俊 +1 位作者 卢建宁 赵光宙 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2005年第B08期87-93,共7页
Multi-objective robust state-feedback controller synthesis problems for linear discrete-time uncertain systems are addressed. Based on parameter-dependent Lyapunov functions, the Gl2 and GH2 norm expressed in terms of... Multi-objective robust state-feedback controller synthesis problems for linear discrete-time uncertain systems are addressed. Based on parameter-dependent Lyapunov functions, the Gl2 and GH2 norm expressed in terms of LMI (Linear Matrix Inequality) characterizations are further generalized to cope with the robust analysis for convex polytopic uncertain system. Robust state-feedback controller synthesis conditions are also derived for this class of uncertain systems. Using the above results, multi-objective state-feedback controller synthesis procedures which involve the LMI optimization technique are developed and less conservative than the existing one. An illustrative example verified the validity of the approach. 展开更多
关键词 Gl2 and GH2 performance Multi-objective optimization Robust controller synthesis Parameter-dependent Lyapunov functions Convex polytopic uncertain system
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Durability of sea-sand containing concrete:Effects of chloride ion penetration 被引量:12
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作者 Yin Huiguang Li Yan +1 位作者 Lv Henglin Gao Quan 《Mining Science and Technology》 EI CAS 2011年第1期123-127,共5页
This paper describes an orthogonal experiment on the effect of water/cement ratio,water consumption per cubic meter,curing time,and type of sand on the response"resistance to chloride ion penetration".A sea-sand con... This paper describes an orthogonal experiment on the effect of water/cement ratio,water consumption per cubic meter,curing time,and type of sand on the response"resistance to chloride ion penetration".A sea-sand containing concrete was used for the trials.An analysis of chloride ion diffusion coefficients at different factor levels was performed.A predictive model of chloride ion diffusion in concrete is developed through regression analysis.The experimental results show that when the water/cement ratio varies from 0.45 to 0.60,and the water consumption per cubic meter varies from 185 to 215 kg,and the curing time varies from 30 to 180 d then the size of the effects fall in the order(most significant first): curing time,type of sand,water consumption per cubic meter,and water/cement ratio.Chloride ion penetration is reduced,and better durability of the concrete is observed,with longer curing times,less water consumption per cubic meter,and a smaller water/cement ratio. 展开更多
关键词 Sea-sand concrete Durability Chloride ion diffusion coefficient Predictive model
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Improved Consensus Speed for Discrete-Time Multi-agent Systems
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《Journal of Donghua University(English Edition)》 EI CAS 2013年第6期461-465,共5页
The consensus problem of a linear discrete-time multi- agent system with directed communication topologies was investigated. A protocol was designed to solve consensus with an improved convergence speed achieved by de... The consensus problem of a linear discrete-time multi- agent system with directed communication topologies was investigated. A protocol was designed to solve consensus with an improved convergence speed achieved by designing protocol gains. The clo6ed-loop multi.agent system converged to an expected type of consensus function, which was divided into four types: zero, non- zero constant vector, bounded trajectories, and ramp trajectories. An algorithm was further provided to construct the protocol gains, which were determined in terms of a classical pole placement algorithm and a modified algebraic Riccati equation. Finally, an example to illustrate the effectiveness of theoretical results was presented. 展开更多
关键词 discrete-time multi-agent consensus function consensus speed
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LINEAR QUADRATIC REGULATION FOR DISCRETE-TIME SYSTEMS WITH INPUT DELAY:SPECTRAL FACTORIZATION APPROACH
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作者 Hongguo ZHAO Huanshui ZHANG +1 位作者 Hongxia WANG Chenghui ZHANG 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2008年第1期46-59,共14页
The infinite-horizon linear quadratic regulation (LQR) problem is settled for discretetime systems with input delay. With the help of an autoregressive moving average (ARMA) innovation model, solutions to the unde... The infinite-horizon linear quadratic regulation (LQR) problem is settled for discretetime systems with input delay. With the help of an autoregressive moving average (ARMA) innovation model, solutions to the underlying problem are obtained. The design of the optimal control law involves in resolving one polynomial equation and one spectral factorization. The latter is the major obstacle of the present problem, and the reorganized innovation approach is used to clear it up. The calculation of spectral factorization finally comes down to solving two Riccati equations with the same dimension as the original systems. 展开更多
关键词 Diophantine equation infinite-horizon LQR reorganized innovation spectral factorization stochastic backwards systems.
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