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Optimal guaranteed cost control for fuzzy descriptor systems with time-varying delay

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Journal of Systems engineering and Electronics 2008年第3期19卷 584-591页

作者： Tian Weihua1,2.& Zhang Huaguang3 1. school of information {2. and engineering, Northeastern Univ., Shenyang 110004, P. R. china 2. Dept. of Automatic Control, Shenyang Inst. of engineering, Shenyang 110136, P. R. china 3. school of information {2. and engineering, Northeastern Univ., Shenyang 110004, P. R. china. (Received December 2., 2.06) [a]school of information {2. and engineering Northeastern Univ. Shenyang 110004 P. R. china [b]Dept. of Automatic Control Shenyang Inst. of engineering Shenyang 110136 P. R. china [c]school of {2. science and engineering Northeastern Univ. Shenyang 110004 P. R. china

Based on the delay-independent rule, the problem of optimal guaranteed cost control for a class of Takagi-Sugeno （T-S） fuzzy descriptor systems with time-varying delay is studied. A linear quadratic cost function is considered as the performance index of the closed-loop system. Sufficient conditions for the existence of guaranteed cost controllers via state feedback are given in terms of linear matrix inequalities （LMIs）, and the design of an optimal guaranteed cost controller can be reduced to a convex optimization problem. It is shown that the designed controller not only guarantees the asymptotic stability of the closed-loop fuzzy descriptor delay system, but also provides an optimized upper bound of the guaranteed cost. At last, a numerical example is given to illustrate the effectiveness of the proposed method and the perfect performance of the optimal guaranteed cost controller.

关键词： fuzzy descriptor systems optimal guaranteed cost control time-varying delay linear matrix inequalities (LMIs).

Effect of Strain on the Electrical Resistance of Carbon Nanotube/Silicone Rubber Composites

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Journal of Wuhan University of Technology(Materials science) 2011年第5期26卷 812-816页

作者：曾尤 school of Materials science and {2. Shenyang Jianzhu University

Carbon nanotube （CNT） filled silicone rubber （SR） composites were synthesized by in situ *** effect of strain on the electrical resistance of the CNT/SR composites and the structure evolution of CNT networks during tensile deformation were *** results showed that the CNT/SR composites had high sensitivity of resistance-strain *** a wide strain range （0-12.%）,the change of resistivity could reach 107,which was closely associated with the evolution process of the conductive CNT-network *** volume expansion of the composites in the tensile process led to a gradual decrease in the volume fraction of CNTs with the strain *** CNT loading was lower than the percolation threshold,CNT network was in disconnected state with a rapid increase in electrical resistance of the ***,the CNT loading had remarkable effect on the sensitivity of resistance-strain response in the composites.

关键词： carbon nanotubes silicone rubber composite resistance-strain response

Rock matrix-fractured media model for heterogeneous and fractured coal bed

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中国有色金属学会会刊：英文版 2011年第S3期21卷 621-625页

作者： ZHANG Chun-hui1, YU Guang-ming2. ZHANG Chun1 1. school of Civil engineering, Hebei University of {2. and Technology, Shijiazhuang 050018, china 2. school of Civil engineering, Qingdao Technological University, Qingdao 2.6033, china [a] school of Civil engineering Hebei University of Science and Technology Shijiazhuang 050018 China [b] school of Civil engineering Qingdao Technological University Qingdao 266033 China

Coal was considered rock matrix-fractured media composed of rock matrix and fractures, and the rock matrix-fractured media model for heterogeneous and fractured coal bed was presented. In this model the rock matrix is heterogeneous, and the mechanical parameters such as elastic modulus and strength follow Weibull distribution. Fractures in coal bed were generated with the discrete fracture network method, and the properties of fractures were simulated with Desai element. Then the virtual generating system (VGS) of natural heterogeneous and fractured coal bed was developed in Matlab 6.0. The coupled model of gas flow and deformation process based on the rock matrix-fractured media model method and VGS for heterogeneous and fractured coal bed was presented, and the numerical code was developed in Matlab 6.0. The gas flow process in the heterogeneous and fractured coal bed was simulated in a numerical case. The main conclusions are: 1) The natural heterogeneous and fractured coal bed could be simulated by the rock matrix-fractured media model and VGS; 2. The fractures connected with the well have much more effects on gas flow than those non-connected.

关键词： heterogeneity fractures rock matrix-fractured media

Manifold contraction for semi-supervised classification

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science china({2. sciences) 2010年第6期53卷 1170-1187页

作者： HU EnLiang 1,2., CHEN SongCan 1 & YIN XueSong 1 1 school of Computer science & {2., nanjing University of Aeronautics & Astronautics, nanjing 2.0016, china 2.school of Mathematics, Yunnan Normal University, Kunming 650092. china 1. school of Computer science & {2. Nanjing University of Aeronautics & Astronautics Nanjing 210016 China2. School of Mathematics Yunnan Normal University Kunming 650092 China

The generalization ability of classification is often closely related to both the intra-class compactness and the inter-class *** to the fact that many current dimensionality reduction methods, regarded as a pre-processor, often lead to the poor classification performance on real-life data, in this paper, a new data preprocessing technique called manifold contraction(MC) is proposed for the classification-oriented learning *** main motivation behind MC lies in seeking a proper mapping of contracting the given multiple-manifold data such that the ratio of the intra-class to the inter-class scatters is ***, in order to properly control the contraction level in MC, an adaptive MC(AMC) criterion is developed in the semi-supervised *** to its generality, MC can be not only applied in original space and reproducing kernel Hilbert space(RKHS), but also easily incorporated with dimensionality reduction method for further improvement of classification *** final experimental results show that MC, as a data preprocessor, is effective and promising in the subsequent classification learning, especially in small-size labeled sample case.

关键词： manifold learning dimensionality reduction lower-dimensional embedding semi-supervised learning classification manifold contraction adaptive manifold contraction

Effect of Preparation Methods on Mechanical Properties of PVA/HA Composite Hydrogel

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Journal of Bionic engineering 2010年第3期7卷 235-243页

作者： Dekun Zhang~1, Junjie Duan~1, Dagang Wang~2. Shirong Ge~2.1. school of Materials science and {2., china University of Mining and Technology Xuzhou 2.1116, P. R. china 2. school of Mechanical and Electrical {2., china University of Mining and Technology, Xuzhou 2.1116, P. R. china [a] school of Materials science engineering China University of Mining Technology Xuzhou 221116 P. R. China [b] School of Mechanical Electrical engineering China University of Mining Technology Xuzhou 221116 P. R. China

Poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) composite hydrogel specimens were prepared with 15% PVA and 1%,2., 3%, 4% and 5% HA by repeated freezing-thawing. The tests of static and dynamic mechanical properties were carried out todiscuss the influence of different contents of HA and freezing-thawing cycles on the mechanical properties of PVA/HA compositehydrogel. The results of static mechanical tests showed that the PVA/HA composite hydrogel with 3% HA and ninefreezing-thawing cycles had excellent stress relaxation properties, higher relaxation ratio, lower stress equilibrium value andpresented better properties of creep and recovery. The results of dynamic mechanical test showed that the PVA/HA compositehydrogel with nine freezing-thawing cycles had higher storage modulus and loss modulus, so was the PVA/HA compositehydrogel with 3% HA.

关键词： composite hydrogel HA contents freezing-thawing cycles static properties dynamic properties

Stability of a linear oscillator with damping force of the fractional-order derivative

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science china(Physics,Mechanics & Astronomy) 2010年第2期53卷 345-352页

作者： WANG ZaiHua1,2.& HU HaiYan1 1 Institute of Vibration engineering Research,nanjing University of Aeronautics and Astronautics,nanjing 2.0016,china 2.Institute of science,PLA University of science and Technology,nanjing 2.1101,china 1. Institute of Vibration engineering Research Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. Institute of Science PLA University of Science and Technology Nanjing 211101 China

It begins with the study of damping representation of a linear vibration system of single degree of freedom (SDOF),from the view point of fractional calculus. By using the idea of stability switch,it shows that the linear term involving the fractional-order derivative of an order between 0 and 2.always acts as a damping force,so that the unique equilibrium is asymp-totically stable. Further,based on the idea of stability switch again,the paper proposes a scheme for determining the stable gain region of a linear vibration system under a fractional-order control. It shows that unlike the classical velocity feedback which can adjust the damping force only,a fractional-order feedback can adjust not only the damping force,but also the elastic re-storing force,and in addition,a fractional-order PDα control can either enlarge the stable gain region or narrow the stable gain region. For the dynamic systems described by integer-order derivatives,the asymptotical stability of an equilibrium is guaranteed if all characteristic roots stay in the open left half-plane,while for the systems with fractional-order derivatives,the asymptotical stability of an equilibrium is guaranteed if all characteristic roots stay within a sector in the complex plane. Analysis shows that the proposed method,based on the idea of stability switch,works effectively in the stability analysis of dynamical systems with fractional-order derivatives.

关键词： vibration system fractional-order derivative asymptotical stability stability switch

Delayed Hopf bifurcation in time-delayed slow-fast systems

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science china(Technological sciences) 2010年第3期53卷 656-663页

作者： ZHENG YuanGuang1 & WANG ZaiHua1,2.1 Institute of Vibration engineering Research,nanjing University of Aeronautics and Astronautics,nanjing 2.0016,china 2.Institute of science,PLA University of science and Technology,nanjing 2.1101,china 1. Institute of Vibration engineering Research Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. Institute of Science PLA University of Science and Technology Nanjing 211101 China

This paper presents an investigation on the phenomenon of delayed bifurcation in time-delayed slow-fast differential *** the two delayed's have different *** delayed bifurcation means that the bifurcation does not happen immediately at the bifurcation point as the bifurcation parameter passes through some bifurcation point,but at some other point which is above the bifurcation point by an obvious *** a time-delayed system,the evolution of the system depends not only on the present state but also on past *** this paper,the time-delayed slow-fast system is firstly simplified to a slow-fast system without time delay by means of the center manifold reduction,and then the so-called entry-exit function is defined to characterize the delayed bifurcation on the basis of Neishtadt's *** shows that delayed Hopf bifurcation exists in time-delayed slow-fast systems,and the theoretical prediction on the exit-point is in good agreement with the numerical calculation,as illustrated in the two illustrative examples.

关键词： time delay delayed bifurcation Hopf bifurcation slow-fast systems exit-point entry-exit function

Three-dimensional subwavelength components utilizing THz surface plasmons

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science china({2. sciences) 2012年第1期55卷 79-89页

作者： ZHOU YongJin,JIANG Quan&CUI TieJun State Key Laboratory of Millimeter Waves,school of information {2. and engineering,southeast University,nanjing 2.0096,china 1. State Key Laboratory of Millimeter Waves School of Information Science and Engineering Southeast University Nanjing 210096 China

Since surface plasmons(SPs)are not constrained by the diraction limit,they have important potential applications in the optical,terahertz(THz),and microwave *** this paper,we firstly present a review of three-dimensional(3D) bidirectional and multi-directional THz SP splitters based on the rectangular metallic groove gratings with finite thickness,in which a metallic wire was used to excite the THz *** experimental verifications of such splitters have been implemented in the microwave frequencies,and the measurement results have excellent agreements to the full-wave *** improve the performance,a 3D bidirectional THz SP splitter with the transverse confinement and a 3D bidirectional bending THz SP splitter are then proposed,which have shown very good splitting performance,compact sizes,and better transverse confinement of EM ***,a broadband slow-wave system of subwavelength thickness is reviewed and a new bending slow-wave system utilizing THz SPs is *** and simulations in microwave frequencies have good agreements,showing the validity of these components.

关键词： surface plasmons surface waves terahertz slow wave splitter

Surface Modification of Silk Fibroin Films with Zwitterionic Phosphobetaine to Improve the Hemocompatibility

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Journal of Wuhan University of Technology(Materials science) 2010年第6期25卷 969-974页

作者：蒋雪峰陈强 school of Chemistry and Chemical engineering Nanjing University

Zwitterionic phosphobetaine bearing a hydroxyl and a zwitterionic group,8-hydroxy-2.octyl phosphorylcholine（HOPC）,was synthesized and constructed to the surface of silk fibroin（SF） films in order to improve the hemocompatibility of fibroin films by a an isocyanate head *** surface characteristics of the modified films were measured by attenuated total reflection Fourier transform infrared spectroscopy（ATR-FTIR） and electron spectroscopy for chemical analysis（ESCA）,displaying the successful immobilization of Zwitterionic phosphobetaine on the surface of these fibroin ***,the further platelet adhesion test in platelets rich plasma（PRP） of human beings showed the zwitterionic phosphobetaine led mainly to good *** experimental results indicated a reasonable approach to improve the blood compatibility of fibroin films.

关键词： zwitterionic phosphobetaine silk fibroin blood compatibility platelet adhesion