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Input-output approach to robust stability and stabilization for uncertain singular systems with time-varying discrete and distributed delays

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第4期9卷 546-551页

作者： Hui-jiao WANG An-ke XUE Yun-fei GUO ren-quan lu Institute of Automation Zhej iang Sci- Tech University Hangzhou 310018 China Institute of Information and Control Hangzhou Dianzi University Hangzhou 310018 China

Based on input-output approach, the robust stability and stabilization problems for uncertain singular systems with time-varying delays are investigated. The parameter uncertainties are assumed to be norm-bounded and the time-varying delays include both discrete delay and distributed delay. By introducing a new input-output model, the time-delay system is embedded in a family of systems with a forward system without time delay and a dynamical feedback uncertainty. A sufficient and necessary condition, which guarantees the system regular, impulse-free and stable for all admissible uncertainties, is obtained. Based on the strict linear matrix inequality, the desired robust state feedback controller is also obtained. Finally, a numerical example is provided to demonstrate the application of the proposed method.

关键词： Robust stability Input-output stability Singular system Time-varying delay Linear matrix inequality (LMI)

Microstructure and Property of HD Die Steel With Unsmoothed Surface With Various Laser Parameters

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Journal of Iron and Steel Research International 2008年第3期15卷 52-56页

作者： CHEN Li ZHOU Hong ZHAO Yu ren lu-quan School of Materials Science and Engineering Changchun University of Technology Changchun 130012 Jilin China The Key Laboratory of Automobile Materials The Ministry of Education Jilin University Changchun 130025 Jilin China The Key Lab of Bionic Materials The Ministry of Education Jilin University Changchun 130025 Jilin China

The reticulate unsmoothed surfaces on HD die steel, which imitate the surface of soil-burrowing animals （such as the dung beetle, earthworm, pangolin, and ant） are produced with various laser parameters. The characteristics （including width, depth, area ratio, and volume）, microstructure, and hardness of the unsmoothed units are studied. At the same time, the wear resistance of the material with an unsmoothed surface is measured. The results show that the width and volume of the unit increase, the microstructure becomes coarser, the hardness decreases, and the wear resistance improves with the increase of the current intensity and pulse duration within a certain range. However, there is little difference between the extent to which the wear resistance of the material increases and the unsmoothed surface, when the current intensity and pulse duration increase to some extent. The wear resistance of the unsmoothed material under 300 A or 20 ms is better in the experiments. The improving extent of the wear resistance lies in a combination of the characteristics, microstructure, and hardness of the unsmoothed unit. An unsmoothed material with better properties can be processed if the laser parameters are well matched.

关键词： microstructure property laser parameter unsmoothed surface

On exponential stability for systems with state delays

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第8期8卷 1296-1303页

作者： CHEN Yun XUE An-ke GE Ming WANG Jian-zhong lu ren-quan Institute of Operational Research and Cybernetics Hangzhou Dianzi University Hangzhou 310018 China National Laboratory of Industrial Control Technology. Zhejiang University Hangzhou 310027 China Institute of Information and Control Hangzhou Dianzi University. Hangzhou 310018 China

This paper considers the issue of delay-dependent exponential stability for time-delay systems. Both nominal and uncertain systems are investigated. New sufficient conditions in terms of linear matrix inequalities(LMIs) are obtained. These criteria are simple owing to the use of an integral inequality. The model transformation approaches,bounding techniques for cross terms and slack matrices are all avoided in the derivation. Rigorous proof and numerical examples showed that the proposed criteria and those based on introducing slack matrices are equivalent.

关键词： Exponential stability Uncertain time-delay systems Integral inequality Slack matrix Linear matrix inequality (LMI)

Properties of 3Cr2W8V Die Steel With Striations Processed by Laser

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Journal of Iron and Steel Research International 2009年第4期16卷 39-43页

作者： CHEN Li ZHOU Hong ZHANG Zhi-hui ren lu-quan School of Materials Science and Engineering Changchun University of Technology Changchun 130012Jilin China The Key Laboratory of Automobile Materials of the Ministry of Education Jilin UniversityChangchun 130025 Jilin China The Key Laboratory for Terrain Machinery Bionics Engineering of theMinistry of Education Jilin University Changchun 130025 Jilin China

The striations on the surface of 3Cr2W8V die steel were processed by laser. The microstructure, hardness, wear resistance and thermal fatigue behavior of the specimens processed by laser were measured. The appearance and mechanism of thermal fatigue crack propagation in the zone processed by laser were observed and discussed. The results show that the wear resistance and thermal fatigue resistance of materials processed by laser are all better than those of the unprocessed material. The processed zone by laser plays a role in baffling wearing process and crack propagation. The pile-nail effect of processed zone is the main factor for improving the wear resistance and thermal fatigue resistance of material.

关键词： laser processing die steel property

Characterization and Wettability of ZnO Film Prepared by Chemical Etching Method

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Chemical Research in Chinese Universities 2013年第2期29卷 333-337页

作者： GUO Hua-xi JIA Hui-ying ZENG Jian-bo CONG Qian ren lu-quan Key Laboratory of Bionic Engineering Ministry of Education Jilin University Changchun 130025 P. R. China

ZnO thin films were prepared by a chemical etching method and their wettability was investigated. The structure and surface composition structure were characterized by means of scanning electron microscopy, X-ray photoelectronic spectrometry（XPS）, X-ray diffraction（XRD） and Raman spectrometry. These analyses reveal that the etched films were large-scale micro-nanohierarchical structures composed of a Zn core and a ZnO coating. Superhy- drophobic surfaces with water contact angles of over 150~ were obtained by n-octadecanethiol（ODT） modification. The XPS and Raman results indicate that ODT molecules were bound to the ZnO surface with the S head group by forming Zn--S bond.

关键词： ZnO Chemical etching Micro-nanostructure Raman spectrometry Wettability

A Computational Model of Soil Adhesion and Resistance for a Non-smooth Bulldozing Plate

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Journal of Bionic Engineering 2005年第3期2卷 145-150页

作者： Shi Wei-ping ren lu-quan Tian Li-mei The Key Lab of Terrain-Machinery Bionic Engineering （Ministry of Education China） Jilin University Changchun 130022 P. R. China Department of Mathematics Jilin University Changchun 130012 P. R. China

Adhesive forces exist between soil and the surfaces of soil-engaging components; they increase working resistance and energy consumption. This paper tries to find an approach to reduce the adhesion and resistance of bulldozing plate. A simplified mechanical model of adhesion and resistance between soil and a non-smooth bulldozing plate is proposed. The interaction force between moist soil and a non-smooth bulldozing plate is analyzed. The pressure and friction distribution on the bulldozing plate are computed, and the anti-adhesive effect of a corrugated bulldozing plate is simulated numerically. Numerical results show that the wavy bulldozing plate achieves an effective drag reduction in moist soil. The optimal wavy shape of the corrugated bulldozing plate with the minimal resistance is designed. The basic principle of reducing soil adhesion of the non-smooth surface is discovered.

关键词： non-smooth surface bulldozing plate reducing adhesion and resistance

Tribological Behavior of Gampsocleis Gratiosa Foot Pad Against Vertical Flat Surfaces

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Journal of Bionic Engineering 2005年第4期2卷 187-194页

作者： Chen Dong-hui Tong Jin Sun Ji-yu ren lu-quan Key Laboratory of Terrain Machine Bionics Engineering （Ministry of Education China） jilin University at Nanling Campus Changchun 130022 P.R. China

Some tribological behavior between mature Gampsocleis gratiosa foot pads and vertical flats of different materials were studied in this work. stereomicroscope （SMS） and scanning electron microscope （SEM） were used to measure the morphology of the Gampsocleis gratiosa foot pads. An atomic force microscope （AFM） was used to measure the morphologies of the surfaces of glass and a wall doped with calcium carbonate material. The attaching behavior of Gampsocleis gratiosa feet on the two vertical surfaces was observed. The attaching force （perpendicular to the vertical surface） and the static frictional force （along the direction of gravitation） of Gampsocleis gratiosa foot pads on a vertical glass were measured. It was shown that the average attaching force is 50.59 mN and the static frictional force is 259.10 mN. The physical models of the attaching interface between Gampsocleis gratiosa foot pads and the two vertical surfaces were proposed. It was observed that the foot pads are smooth in macroscale; however, the pad surface is composed by approximate hexagonal units with sizes of 3 μm to 7 μm in microscale; the adjacent units are separated by nanoscale grooves. The Observations showed that the Gampsocleis gratiosa can not climb the vertical calcium carbonate wall; in contrast, they can easily climb the vertical glass surface. Based on the features of the geometrical morphologies of the foot pads and the glass surface, we speculate that the attaching force and strong static frictional force are attributed to the interinlays between the deformable Gampsocleis gratiosa foot pads and the nanoscale sharp tips of the glass surface.

关键词： Gampsocleis gratiosa foot pad surface microstructure static friction tribology

Tangent Resistance of Soil on Moldboard and the Mechanism of Resistance Reduction of Bionic Moldboard

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Journal of Bionic Engineering 2005年第1期2卷 33-46页

作者： Deng Shi-qiao ren lu-quan Liu Yan Han Zhi-wu Key Laboratory of Terrain-Machine Bionics Engineering （Ministry of Education China） Jilin University Changchun 130022 P. R. China

The tangent resistance on the interface of the soil-moldboard is an important component of the resistance to moving soil . We developed simplified mechanical models to analyze this resistance. We found that it is composed of two components, the frictional and adhesive resistances. These two components originate from the soil pore, which induced a capillary suction effect, and the soil-moldboard contact area produced tangent adhesive resistance. These two components varied differently with soil moisture. Thus we predicted that resistance reduction against soil exerted on the non-smooth bionic moldboard is mainly due to the elimination of capillary suction and the reduction of physical-chemical adsorption of soil.

关键词： agriculture engineering bionic moldboard interracial tangent resistance soil adhesion capillary suction

Fabrication of Large-scale Nanostructure by Langmuir-Blodgett Technique

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Journal of Bionic Engineering 2006年第2期3卷 59-62页

作者： Lü Zhi-cheng Ruan Wei-dong Ji Nan ren lu-quan Cong Qian Zhao Bing Key Laboratory for Supramolecular Structure and Materials （Ministry of Education P. R. China） Qianwei Campus Jilin University Changchun 130012 P. R. China Key Laboratory for Terrain-Machine Bionics Engineering （Ministry of Education P. R. China） Nanling Campus Jilin University Changchun 130022 P. R. China

Monolayer of polymer latex spheres was prepared at the air/water interface and deposited onto glass slides through Langmuir-Blodgett （LB） technique. Large-scale, high quality hexagonally close-packed domains were found in scanning electron microscopic pictures. Details of the monolayer-forming ability were discussed. Suitable surface characteristics of the colloidal particles, especially the hydrophilic and hydrophobic properties, are the keys for the formation of ordered monolayer films. The film can be transferred onto various kinds of substrates, even high curvature surface articles, such as fibers, decorations etc, can also be used as substrates. The advantages of this fabrication method of polymer latex spheres monolayer are fast, flexible, simple and very neat.

关键词： nanosphere monolayer Langmuir-Blodgett technique structural colour