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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 {2. of Aeronautics and Astronautics,nanjing 2.0016,china 2.Institute of Science,PLA {2. 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

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 {2. of Aeronautics and Astronautics,nanjing 2.0016,china 2.Institute of Science,PLA {2. 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

Influence of Absolute Basicity and Capillary Porosity on Carbonation of Concrete

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Journal of Wuhan university of Technology(Materials Science) 2010年第5期25卷 889-892页

作者：巴明芳 School of Materials Science and Engineering Southeast University Jiangsu Key Lab of Construction Materials

The single influence of capillary porosity and coupling effects of absolute basicity and capillary porosity on concrete carbonation were investigated. The experimental results showed that carbonation rate of concrete at a given absolute basicity （AB） increased moderately with the increase of the porosity ranging from 6.2. to 9.2.%, and increased rapidly with porosity from 9.2.% to 12.8%.The coupling effect mainly embodied in disappeared mutation point of capillary porosity, and the distributing regions of carbonation depth were clearly partitioned in the coupling influence of absolute basicity and capillary porosity. A design method on carbonation related durability of concrete based on the coupling effects was proposed.

关键词： absolute basicity capillary porosity coupling effects carbonation rate

Design,analysis and control of hybrid excited doubly salient stator-permanent-magnet motor

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Science china(Technological Sciences) 2010年第1期53卷 188-199页

作者： ZHU XiaoYong1,2.& CHENG Ming1 1 Engineering research Center for Motion Control of MOE,School of Electrical Engineering,southeast university,{2.,china 2.School of Electrical and Information Engineering,Jiangsu university,Zhenjiang 2.2.13,china 1. Engineering research Center for Motion Control of MOE School of Electrical Engineering Southeast University Nanjing 210096 China2. School of Electrical and Information Engineering Jiangsu University Zhenjiang 212013 China

In this paper,a new hybrid excited doubly salient stator-permanent-magnet motor is proposed,where both permanent magnets and DC field windings are located in the *** theory,the mathematical model and design method of the motor are *** corresponding output power equation and the relationship between the flux control capability and the extended speed range are deduced in *** using an efficient "one-step" three-dimensional(3D) finite element method,the electromagnetic performances are analyzed,in which the leakage flux outside the stator circumference and end-effect are taken into *** on the operation principle of the motor,the control strategy and scheme are developed and implemented *** experimental results and finite element analysis show that the proposed motor not only maintains the advantages of doubly salient permanent magnet motors,but also offers high energy efficiency over a wide speed range,which makes the motor an interesting candidate for electric vehicles.

关键词： stator permanent magnet motor hybrid excitation doubly salient finite element method flux weakening control

Special magnetic phenomena in heavily doped La_(0.7-x)Dy_xSr_(0.3)MnO_3 system

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Science china(Physics,Mechanics & Astronomy) 2008年第1期51卷 90-97页

作者： LIU Ning 1,2.,YAN GuoQing 1,3 ,CAI ZhiRang 1 ,PI Li 2.,ZHANG Bei 2.&TONG Wei 2.1 Department of Physics,Suzhou College,Suzhou 2.4000,china 2.Structure research Laboratory,{2. of Science and Technology of china,Hefei 2.002.,china 3 national Laboratory of Solid State Microstructures,Physics Department,nanjing {2.,nanjing 2.0093,china 1. Department of Physics Suzhou College Suzhou 234000 China 2. Structure research Laboratory University of Science and Technology of China Hefei 230026 China 3. national Laboratory of Solid State Microstructures Physics Department Nanjing University Nanjing 210093 China

The magnetism in heavily Dy doped La0.7-xDyxSr0.3MnO3(0.40≤x≤0.70)system is studied in this *** M-T relation seems to be complicated with the increase of *** sample with x=0.40,AFM behavior exists at T≤TN and M-T curves under zero field cooling(ZFC)and field cooling(FC)exhibit typical behavior of spincluster glass state above *** the sample with x=0.50,the M-T curve under ZFC exhibits a valley at a low temperature while the M-T curve under FC exhibits the negative magnetization below *** samples with x=0.60,0.70,their ZFC M-T curves are similar to that of x=0.50,but the FC M-T curves do not exhibit negative values any *** the peculiar phenomena above are well explained by Néel double-lattice model combined with M-H relation at typical *** molecular field theory fits well the negative magnetization for x=0.50.

关键词： heavily doped special magnetic phenomena double-lattice model

Comparison of the fracture process of the rubberized concrete and plain concrete under bending load

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Science china(Technological Sciences) 2010年第6期53卷 1526-1533页

作者： ZHANG YaMei1,WANG Chao2.LU Yi1 & MA AiBin2.1 Jiangsu Key Laboratory of Construction Materials,southeast university,nanjing 2.1189,{2. 2.College of Materials Science and Engineering,Hohai university,nanjing 2.0098,{2. 1. Jiangsu Key Laboratory of Construction Materials Southeast University Nanjing 211189 China2. College of Materials Science and Engineering Hohai University Nanjing 210098 China

Acoustic emission (AE) technique is employed to investigate the damage process of the notched plain concrete and rubberized concrete specimens under 3-point bending *** signals in the fracture process of notched specimens are illustrated by analyzing the distribution of amplitude and hit rate of AE *** signals in the rubberized concrete have lower activity and amplitude than in the plain *** AE location analysis,it is found that the high energy events mainly are distributed near the notch *** to AE energy,the fracture process zone (FPZ) is *** comparing the FPZ of both concretes,it is found that the incorporation of rubber particles in concrete can greatly alleviate the damage process of concrete specimens and the damage zone in the rubberized concrete is much smaller than in the plain *** moment tensor is also used to analyze the type of cracks and it is found that tensile cracks dominate the early period of loading,while shear cracks become dominant with propagation of cracks in late load period.

关键词： concrete rubberized concrete acoustic emission damage moment tensor

Dispersion of ventricular mRNA of RyR2.and SERCA2.associated with arrhythmogenesis in rats

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Acta Pharmacologica Sinica 2004年第6期25卷 36-41页

作者： Hong-lan WANG, De-zai DAI2. Feng GAO3, Yan-pin ZHANG3, Feng LU research Division of Pharmacology, china Pharmaceutical {2., nanjing 2.0009, china 3Laboratorial Center ofMedicine, southeast university, nanjing 2.0009, china research Division of Pharmacology China Pharmaceutical University Nanjing 210009 China

AIM: To investigate the effect of CPU86017 on the changes of mRNA abundance of different calcium handling system in infarcted heart. METHODS: Rats were subjected to left coronary ligation to induce myocardial infarc- tion (MI). The treatment with either propranolol (Pro) 5 mg/kg ip or CPU86017 1, 2. and 4 mg/kg ip was initiated on the next day of operation and continued for 2. d. Medication with isoproterenol (Isop) 3 mg/kg sc started on the d 17-2.. Ventricular mRNA abundance of ryanodine receptor 2.(RyR2., sarcoplasmic reticulum Ca2.-ATPase (SERCA2., L-type Ca2. channel, and Na+/Ca2.exchanger (NCX1) were measured. RESULTS: Arrhythmic scores (AS) in the Isop group was raised up to 5.2.±1.75 (P2.2.±2.04 and sham group 1.50±1.73. The AS was depressed by Pro (1.63±1.53, P2.and 4 mg/kg (3.00±1.2., and 1.70±1.85, P2. and SERCA2.was associated with an increase in AS in Isop group, and it was much depressed in the left than the right ventricle. The dispersion and depression of mRNA were restored significantly by Pro and CPU86017, asso- ciated with suppression on AS. In Isop group, the mRNA abundance of L-type Ca2. channel was not changed; and a moderate increase in the mRNA of NCX1 was seen, the changes were regressed by Pro and CPU86017. CONCLUSION: Isop-induced arrhythmogenesis in MI heart was correlated mainly with a dispersion of depressed mRNA abundance in ventricle likely due to the consequence of PKA over-phosphorylation. A suppression of arrhythmia by Pro and CPU86017 resulted from a regression of the dispersion and depression of RyR2.and SERCA2.

关键词： myocardial infarction isoproterenol arrhythmia calcium 4-chlorobenzyltetrahydroberberine

Multivariate analysis in dam monitoring data with PCA

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Science china(Technological Sciences) 2010年第4期53卷 1088-1097页

作者： YU Hong1,2.WU ZhongRu1,2.BAO TengFei1,2.& ZHANG Lan1,2.1 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Hohai university,nanjing 2.0098,{2. 2.national Engineering research Center of Water Resources Efficient Utilization and Engineering Safety,Hohai university,nanjing 2.0098,{2. 1. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China2. National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Hohai University Nanjing 210098 China

Given the limitation of traditional univariate analysis method in processing the multicollinearity of dam monitoring data,this paper reconstructs the multivariate response variables by introducing principal component analysis(PCA) method,explores the ways of determining principal components(PCs),and extracts a few PCs that have major influence on data *** steady observation series,a control field for the whole observation values has been established based upon PCA;for unsteady observation series that have significant tendency,a control field for the future observation values has been constructed according to PC statistical predication *** methods have already been applied to an actual project and the results showed that data interpretation method with PCA can not only realize data reduction,lower data redundancy,and reduce noise and false alarm rate,but also be effective to data analysis,having a broad application prospect.

关键词： dam safety monitoring multivariate response variables principal component analysis data reduction

Study on the thermal stability and electrical properties of the high-k dielectrics (ZrO_2. _x(SiO_2._(1-x)

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Science china(Technological Sciences) 2009年第8期52卷 2222-2226页

作者： Lü ShiCheng1,2. YIN Jiang1,2. XIA YiDong2.3, GAO LiGang2.3 & LIU ZhiGuo2.3 1 Department of Physics, nanjing university, nanjing 2.0093, china 2.national Laboratory of Solid Sate Microstructures, nanjing university, nanjing 2.0093, china 3 Department of Materials Science and Engineering, nanjing university, nanjing 2.0093, china 1. Department of Physics Nanjing University Nanjing 210093 China 2. national Laboratory of Solid Sate Microstructures Nanjing University Nanjing 210093 China 3. Department of Materials Science and Engineering Nanjing University Nanjing 210093 China

(ZrO2.x(SiO2.1-x (Zr-Si-O) films with different compositions were deposited on p-Si(100) substrates by using pulsed laser deposition technique. X-ray photoelectron spectra (XPS) showed that these films remained amorphous after annealing at 800℃ with RTA process in N2.for 60 s. The XPS spectra indi- cated that Zr-Si-O films with x=0.5 suffered no obvious phase separation after annealing at 800℃, and no interface layer was formed between Zr-Si-O film and Si substrate. While Zr-Si-O films with x >0.5 suffered phase separation to precipitate ZrO2.after annealing under the same condition, and SiO2.was formed at the interface. To get a good interface between Zr-Si-O films and Si substrate, Zr-Si-O films with bi-layer structure (ZrO2.0.7(SiO2.0.3/(ZrO2.0.5(SiO2.0.5/Si was deposited. The electrical properties showed that the bi-layer Zr-Si-O film is of the lowest equivalent oxide thickness and good interface with Si substrate.

关键词： high-k dielectric film pulsed laser deposition pseudo ternary alloy