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度量空间中湍流存在的条件
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作者 王芳 简伟刚 王延庚 《西北大学学报(自然科学版)》 CAS CSCD 北大核心 2013年第2期193-197,共5页
目的为得到度量空间中湍流存在的条件。方法以提出两个新概念源不动点及开收敛为基础,利用拓扑学的方法进行研究。结果建立了源不动点和开收敛之间的一些性质,得到湍流存在的充分条件,给出了一个拓扑动力系统拓扑(半)共轭于符号动力系... 目的为得到度量空间中湍流存在的条件。方法以提出两个新概念源不动点及开收敛为基础,利用拓扑学的方法进行研究。结果建立了源不动点和开收敛之间的一些性质,得到湍流存在的充分条件,给出了一个拓扑动力系统拓扑(半)共轭于符号动力系统的一个充要条件。结论丰富了对拓扑动力系统、混沌等问题的研究。 展开更多
关键词 湍流 源不动点 开收敛 拓扑(半)共轭
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Post-Gaussian Effective Potential of Double sine-Gordon Field
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作者 CAIWei-Ran LOUSen-Yue 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第6期1075-1082,共8页
In the framework of the functional integral formalism, we calculate the effective potential of the double sine-Gordon (DsG) model up to the second order with an optimized expansion and the Coleman's normal-orderin... In the framework of the functional integral formalism, we calculate the effective potential of the double sine-Gordon (DsG) model up to the second order with an optimized expansion and the Coleman's normal-ordering prescription. Within the range of convergence, we make a comparison among the classicaland the effective potential of the first and second order. The numerical analysis shows that the DsG post-Gaussian EP possesses some fine global properties and makes a substantial and a concordant quantum correction to the features of the classical potential. 展开更多
关键词 post-gaussian effective potential double sine-gordon field optimizedexpansion
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Global Convergence of a New Restarting Conjugate Gradient Method for Nonlinear Optimizations 被引量:1
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作者 SUN Qing-ying(Department of Applied Mathematics, Dalian University of Technology, Dalian 116024, China Department of Applied Mathematics, University of Petroleum , Dongying 257061, China) 《Chinese Quarterly Journal of Mathematics》 CSCD 2003年第2期154-162,共9页
Conjugate gradient optimization algorithms depend on the search directions with different choices for the parameters in the search directions. In this note, by combining the nice numerical performance of PR and HS met... Conjugate gradient optimization algorithms depend on the search directions with different choices for the parameters in the search directions. In this note, by combining the nice numerical performance of PR and HS methods with the global convergence property of the class of conjugate gradient methods presented by HU and STOREY(1991), a class of new restarting conjugate gradient methods is presented. Global convergences of the new method with two kinds of common line searches, are proved. Firstly, it is shown that, using reverse modulus of continuity function and forcing function, the new method for solving unconstrained optimization can work for a continously dif ferentiable function with Curry-Altman's step size rule and a bounded level set. Secondly, by using comparing technique, some general convergence properties of the new method with other kind of step size rule are established. Numerical experiments show that the new method is efficient by comparing with FR conjugate gradient method. 展开更多
关键词 nonlinear programming restarting conjugate gradient method forcing function reverse modulus of continuity function CONVERGENCE
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Consensus tracking protocol and formation control of multi-agent systems with switching topology 被引量:13
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作者 年晓红 苏赛军 潘欢 《Journal of Central South University》 SCIE EI CAS 2011年第4期1178-1183,共6页
Consensus tracking control problems for single-integrator dynamics of multi-agent systems with switching topology are investigated. In order to design effective consensus tracking protocols for a more general class of... Consensus tracking control problems for single-integrator dynamics of multi-agent systems with switching topology are investigated. In order to design effective consensus tracking protocols for a more general class of networks, which are aimed at ensuring that the concerned states of agents converge to a constant or time-varying reference state, new consensus tracking protocols with a constant and time-varying reference state are proposed, respectively. Particularly, by contrast with spanning tree, an improved condition of switching interaction topology is presented. And then, convergence analysis of two consensus tracking protocols is provided by Lyapunov stability theory. Moreover, consensus tracking protocol with a time-varying reference state is extended to achieve the fbrmation control. By introducing formation structure set, each agent can gain its individual desired trajectory. Finally, several simulations are worked out to illustrate the effectiveness of theoretical results. The test results show that the states of agents can converge to a desired constant or time-varying reference state. In addition, by selecting appropriate structure set, agents can maintain the expected formation under random switching interaction topologies. 展开更多
关键词 multi-agent system consensus protocols formation control switching topology
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Predictive Spectrum Sensing Strategy Based on Reinforcement Learning
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作者 QU Zhaowei CUI Rong +1 位作者 SONG Qizhu YIN Sixing 《China Communications》 SCIE CSCD 2014年第10期117-125,共9页
In this paper,we consider a cognitive radio(CR) system with a single secondary user(SU) and multiple licensed channels.The SU requests a fixed number of licensed channels and must sense the licensed channels one by on... In this paper,we consider a cognitive radio(CR) system with a single secondary user(SU) and multiple licensed channels.The SU requests a fixed number of licensed channels and must sense the licensed channels one by one before transmission.By leveraging prediction based on correlation between the licensed channels,we propose a novel spectrum sensing strategy,to decide which channel is the best choice to sense in order to reduce the sensing time overhead and further improve the SU's achievable throughput.Since the correlation coefficients between the licensed channels cannot be exactly known in advance,the spectrum sensing strategy is designed based on the model-free reinforcement learning(RL).The experimental results show that the proposed spectrum sensing strategy based on reinforcement learning converges and outperforms random sensing strategy in terms of long-term statistics. 展开更多
关键词 cognitive radio spectrum sensing spectrum prediction reinforcement learning
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Free longitudinal vibrations of non-uniform rods 被引量:5
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作者 GUO ShuQi YANG ShaoPu 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第10期2735-2745,共11页
Free longitudinal vibrations of non-uniform rods are investigated by a proposed method, which results in a series solution. In a special case, with the proposed method an exact solution with a concise form can be obta... Free longitudinal vibrations of non-uniform rods are investigated by a proposed method, which results in a series solution. In a special case, with the proposed method an exact solution with a concise form can be obtained, which imply four types of profiles with variation in geometry or material properties. However, the WKB (Wentzel-Kramers-Brillouin) method leads to a series solution, which is a Taylor expansion of the results of the proposed method. For the arbitrary non-uniform rods, the comparison indicates that the WKB method is simpler, but the convergent speed of the series solution resulting from the pro-posed method is faster than that of the WKB method, which is also validated numerically using an exact solution of a kind of non-uniform rods with Kummer functions. 展开更多
关键词 longitudinal vibration non-uniform rod series solution WKB method
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Parameter estimation method based on parameter function surface 被引量:13
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作者 BAO WeiMin ZHANG XiaoQin ZHAO LiPing 《Science China(Technological Sciences)》 SCIE EI CAS 2013年第6期1485-1498,共14页
By analyzing the structure of the objective function based on error sum of squares and the information provided by the objective function, the essential problems in the current parameter estimation methods are summari... By analyzing the structure of the objective function based on error sum of squares and the information provided by the objective function, the essential problems in the current parameter estimation methods are summarized: (1) the information extracted from the objective function based on error sum of squares is unreasonable or even wrong for parameter estimation; and (2) the surface of the objective function based on error sum of squares is more complex than that of the parameter function, which indicates that the optimal parameter values should be searched on the surface of the parameter function instead of the objective function. This paper proposes the concept of sample intersection and demonstrates the uniqueness theorem of intersection point (namely the uniqueness of optimal parameter values). According to the characteristics of parameter function surface and Taylor series expansion, a parameter estimation method based on the sample intersection information extracted from parameter function surface (PFS method) was constructed. The results of theoretical analysis and practical application show that the proposed PFS method can avoid the problems in the current automatic parameter calibration, and has fast convergence rate and good performance in parameter calibration. 展开更多
关键词 parameter estimation objective function surface parameter function surface uniqueness theorem INTERSECTION Taylor series
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