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Science china mathematics 2007年第11期50卷 1661-1672页

作者： rui-ming yao~(1+) li-jun bo~(1,2) 1 department of mathematics,xidian university,xi’an 710071,china 2 School of Mathematical Sciences,Nankai university,Tianjin 300071,china department of mathematics Xidian University Xi’an 710071 China School of Mathematical Sciences Nankai University Tianjin 300071 China

In this paper,we study a discontinuous Galerkin numerical scheme for a class of elliptic stochastic partial differential equations (*** SPDEs) driven by space white noises with homogeneous Dirichlet boundary conditions for two and three space *** also establish L2 error estimates for the *** particular,a numerical test for d = 2 is presented at the end of the article.

关键词： discontinuous Galerkin numerical scheme elliptic SPDEs white noises

Adaptive Iterative Learning Control for Nonlinearly Parameterized Systems with Unknown Time-varying Delay and Unknown Control Direction

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International Journal of Automation and computing 2012年第6期9卷 578-586页

作者： Dan li jun-Min li department of mathematics,xidian university,xi an 710071,china 1. department of mathematics Xidian University Xi’an 710071 China

This paper proposes a new adaptive iterative learning control approach for a class of nonlinearly parameterized systems with unknown time-varying delay and unknown control *** employing the parameter separation technique and signal replacement mechanism,the approach can overcome unknown time-varying parameters and unknown time-varying delay of the nonlinear *** incorporating a Nussbaum-type function,the proposed approach can deal with the unknown control direction of the nonlinear *** on a Lyapunov-Krasovskii-like composite energy function,the convergence of tracking error sequence is achieved in the iteration ***,two simulation examples are provided to illustrate the feasibility of the proposed control method.

关键词： Nonlinearly time-varying parameterized systems unknown time-varying delay unknown control direction composite energy function adaptive iterative learning control.

Adaptive Fuzzy Dynamic Surface Control for a Class of Perturbed Nonlinear Time-varying Delay Systems with Unknown Dead-zone

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International Journal of Automation and computing 2012年第5期9卷 545-554页

作者： Hong-Yun Yue jun-Min li department of Applied mathematics,xidian university,xi an 710071,china 1. department of Applied mathematics Xidian University Xi’an 710071 China

In this paper,adaptive dynamic surface control(DSC) is developed for a class of nonlinear systems with unknown discrete and distributed time-varying delays and unknown *** logic systems are used to approximate the unknown nonlinear ***,by combining the backstepping technique and the appropriate Lyapunov-Krasovskii functionals with the dynamic surface control approach,the adaptive fuzzy tracking controller is *** development is able to eliminate the problem of 'explosion of complexity' inherent in the existing backstepping-based *** main advantages of our approach include:1) for the n-th-order nonlinear systems,only one parameter needs to be adjusted online in the controller design procedure,which reduces the computation burden ***,the input of the dead-zone with only one adjusted parameter is much simpler than the ones in the existing results;2) the proposed control scheme does not need to know the time delays and their upper *** is proven that the proposed design method is able to guarantee that all the signals in the closed-loop system are bounded and the tracking error is smaller than a prescribed error bound,Finally,simulation results demonstrate the effectiveness of the proposed approach.

关键词： Adaptive fuzzy control dynamic surface control(DSC) discrete and distributed time-varying delays Lyapunov-Krasovskii functionals dead-zone

Adaptive Output-feedback Regulation for Nonlinear Delayed Systems Using Neural Network

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International Journal of Automation and computing 2008年第1期5卷 103-108页

作者： Wei-Sheng Chen jun-Min li department of Applied mathematics,xidian university,xi′an 710071,PRC department of Applied mathematics Xidian University Xi’an 710071 PRC

A novel adaptive neural network （NN） output-feedback regulation algorithm for a class of nonlinear time-varying timedelay systems is proposed. both the designed observer and controller are independent of time delay. Different from the existing results, where the upper bounding functions of time-delay terms are assumed to be known, we only use an NN to compensate for all unknown upper bounding functions without that assumption. The proposed design method is proved to be able to guarantee semi-global uniform ultimate boundedness of all the signals in the closed system, and the system output is proved to converge to a small neighborhood of the origin. The simulation results verify the effectiveness of the control scheme.

关键词： Adaptive neural network (NN) output-feedback nonlinear time-delay systems backstepping

Correlation analysis of target echoes using distributed transmit array

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Science china(Information Sciences) 2010年第9期53卷 1860-1868页

作者： JIN ming*,liAO GuiSheng & li jun National Laboratory of Radar Signal Processing,xidian university,xi’an 710071,china 1. National Laboratory of Radar Signal Processing Xidian University Xi’an 710071 China

Transmit diversity multiple-input multiple-output(MIMO) radars decorrelate target echoes on distributed transmit array,and then through closely spaced receivers array estimate the angles of multiple targets using the received target echoes without separating transmitted *** this paper,the target echoes correlation is analyzed under Swerling I and Ⅱ target model *** results show that:(1) Target echoes are uncorrelated under Swerling II model;(2) under Swerling I model,in order to decrease the correlation of target echoes by increasing the number of transmitters,it is required that the normalized covariance matrices of the signals before and after the transmitter number increases should satisfy a relation given in this ***,the results are verified by computer simulations of the target echoes correlation and angles estimation performance.

关键词： multiple-input multiple-output(MIMO) radar transmit diversity target echoes decorrelation

lipschitz equivalence of generalized {1,3,5}-{1,4,5} self-similar sets

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Science china mathematics 2007年第11期50卷 1537-1551页

作者： li-feng xi~(1+) Huo-jun RUAN~2 1 Institute of mathematics,Zhejiang Wanli university,Ningbo 315100,china 2 department of mathematics,Zhejiang university,Hangzhou 310027,china Institute of mathematics Zhejiang Wanli University Ningbo 315100 China department of mathematics Zhejiang University Hangzhou 310027 China

This paper investigates the lipschitz equivalence of generalized {1,3,5}-{1,4,5} self-similar sets D=(r_1D)∪(r_2D+(1+r_1-r_2-r_3)/2)∪(r_3D+1+r_3) and E=(r_1E)∪(r_2E+1-r_2- r_3)∪(r_3E+1-r_3),and proves that D and E... 详细信息

关键词： self-similar set overlap lipschitz equivalence graph-directed construction ergodicity martingale

Experimental　Investigation　of　the　Nonlinear　Coupling　Strength　of　a　Photorefractive　Crystal

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Chinese Journal of Lasers 1995年第1期B4卷 81-86页

作者： WANG Jiayou li xiaochung GUO Siji SHI Sunxiang(department of Applied Physics,xidian university,xian 710071,china) xidian Univ Xi'an China

ＥｘｐｅｒｉｍｅｎｔａｌＩｎｖｅｓｔｉｇａｔｉｏｎｏｆｔｈｅＮｏｎｌｉｎｅａｒＣｏｕｐｌｉｎｇＳｔｒｅｎｇｔｈｏｆａＰｈｏｔｏｒｅｆｒａｃｔｉｖｅＣｒｙｓｔａｌＥｘｐｅｒｉｍｅｎｔａｌＩｎｖｅｓｔｉｇａｔｉｏｎｏｆｔ... 详细信息

ＥｘｐｅｒｉｍｅｎｔａｌＩｎｖｅｓｔｉｇａｔｉｏｎｏｆｔｈｅＮｏｎｌｉｎｅａｒＣｏｕｐｌｉｎｇＳｔｒｅｎｇｔｈｏｆａＰｈｏｔｏｒｅｆｒａｃｔｉｖｅＣｒｙｓｔａｌＥｘｐｅｒｉｍｅｎｔａｌＩｎｖｅｓｔｉｇａｔｉｏｎｏｆｔｈｅＮｏｎｌｉｎｅａｒＣｏｕｐｌｉ...

关键词： photorefractive erystal nonlinear coupling strength

Synthesis and Efficiency of a SphericalMacroporous Epoxy-dicyandiamide ChelateResin for Preconcentrating and SeparatingTrace Au, Hg, Pd and Ru from Samples

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Chemical Research in Chinese Universities 2001年第2期17卷 168-174页

作者： GONG bo-lin, li Xue-qiang and WANG Feng-rong (department of Chemistry, Ningxia university, Yinchuan 750021, china) CHANG xi-jun (department of Chemistry, Lanzhou university, Lanzhou 730000, china) Ningxia Univ Dept Chem Yinchuan 750021 Peoples R China Lanzhou Univ Dept Chem Lanzhou 730000 Peoples R China

A novel spherical macroporous epoxy-dicyandiamide chelate resin was synthesized simply and rapidly from epoxy resin and used for the preconcentration and separation of trace amounts of Au (Ⅲ ), Hg (Ⅱ ), Pd (Ⅳ) and Ru (Ⅲ) ions from solution samples. The analyzed ions can be quantitatively concentrated by the resin at a flow rate of 2. 0 mL/min at pH 4, and can also be desorbed with 15 mL of 4 mol/L HCl + 0. 3 g thiourea from the resin column with recoveries of 96. 5%-99. 0%. After the chelate resin was reused for 7 times, the recoveries of these ions were still over 92%, and 400-1 000 times of excess of Fe(Ⅲ ), Al(Ⅲ ), Ni( II), Mn( Ⅱ ), Cr (Ⅲ ), Cu ( Ⅱ ), Cd (Ⅱ ) and Pb (Ⅱ ) caused little interference with the determination of these ions by an inductively coupled plasma optical emission spectrometer (ICP-OES ). The capacities of the resin for the analytes are in the range of 0. 35~0. 92 mmol/g. The RSDs of the proposed method are in the range of 1. 1 % ~4. 0% for each kind of the analyzed ions. The recoveries of a standard added in real solution samples are between 96. 5% and 98. 5%, and the results for the analyzed ions in a powder sample are in good agreement with their reported values.

关键词： Concentration Separation Macroporous epoxy-dicyandiamide chelate resin Gold Mercury Palladium and ruthenium.

Adaptive Full State Hybrid Projective Synchronization of two Different Hyperchaotic Systems with Fully Uncertain Parameters

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Adaptive Full State Hybrid Projective Synchronization of two...

THE MEASUREMENT OF COMPLEX PERMITTIVITY OF ANISOTROPIC DIELECTRICS BY MEANS OF AN ELECTROMAGNETIC OPEN RESONATOR

2011 Chinese Control and Decision Conference（CCDC）

作者： He Bingli and li junmin are with the department of mathematics,xidian university,xi''an,china 710071.

This paper mainly investigates adaptive hybrid projective synchronization of two different hyperchaotic systems with fully unknown *** on Lyapunov stability theory,adaptive synchronization controllers and parameter update laws are designed such that the states of the drive system and the response system are ultimately asymptotically hybrid projective *** results are presented to show the feasibility and effectiveness of the proposed method.

关键词： Hyperchaotic systems Adaptive control Lyapunov stability theory Hybrid projective synchronization

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Journal of Electronics(china) 1994年第2期11卷 156-163页

作者：夏军梁昌洪 department of Electromagnetic Field Engineering Xidian University Xi'an 710071

By applying the perturbation method and the complex-source-point theory, the theoretical research of measurement of complex permittivity of uniaxial anisotropic materials by means of an electromagnetic open resonator has been made, and the double refraction phenomenon due to anisotropy of measured dielectric materials has been quantitatively analyzed. Finally, measurements have been made on some single-crystal quartz specimens using an automated open resonator measurement system at 8mm band.

关键词： Electromagnetic open resonator Anisotropic dielectrics Complex permittivity Perturbation method Complex-source-point theory