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Sufficient and necessary conditions for Lyapunov stability of Lorenz system and their application

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science china(information sciences) 2010年第8期53卷 1574-1583页

作者： LUO Qi 1 , liAO XiaoXin 2 & ZENG Zhigang 2 1 college of information and control, nanjing university of information science and technology, nanjing 210044, china 2 Department of control science and Engineering, Huazhong university of science and technology, Image Processing and Intelligent control Key Laboratory of Education Ministry of china, Wuhan 430074, china college of information and control Nanjing University of Information Science and Technology Nanjing China Department of control science and Engineering Huazhong University of Science and Technology Image Processing and Intelligent Control Key Laboratory of Education Ministry of China Wuhan China

The sufficient and necessary conditions for Lyapunov stability of the zero equilibrium point of Lorenz system are discussed, and some brief criteria are presented for globally exponential stability, globally asymptotical stability and instability. Furthermore, the behavior of the non-zero equilibrium point of Lorenz system is also investigated, and several sufficient and necessary conditions are provided for locally exponential stability and instability. The established theorems in this paper develop and extend the existing achievements on Lyapunov stability of Lorenz system. In conclusion, by applying the obtained results, some less conservative feedback-control laws are derived to guarantee the globally exponential stability of the chaos control of Chen system, Lu¨ system, Yang-Chen system and yu-Xia li system.

关键词： Lorenz system Lyapunov stability sufficient and necessary condition bifurcation values globally exponential synchronization

MMSE relay precoding schemes based on quantization error compensation for multi-relay system

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science china(information sciences) 2010年第12期53卷 2548-2556页

作者： li Ting 1,2 & YANG LuXi 2 1 college of Communication and information Engineering,nanjing university of Posts and Telecommunications,nanjing 210003,china 2 School of information science and Engineering,Southeast university,nanjing 210096,china college of Communication and information Engineering Nanjing University of Posts and Telecommunications Nanjing China School of information science and Engineering Southeast University Nanjing China

In order to deal with the performance degradation resulting from the quantization error,this paper introduces the statistics of Grassmannian codebook's quantization error into relay precoding design for multirelay *** on the two-step MMSE optimization algorithm for relay precoding and receiver equalizing with full feedback under QoS requirements,we first propose a limited feedback two-step MMSE optimization scheme for relay precoding and receiver equalizing with quantization error compensation,and then we propose a limited feedback joint MMSE optimization scheme for relay precoding and receiver equalizing with quantization error compensation subject to a global power constraint at the output of *** results show that the proposed joint MMSE optimization scheme with quantization error compensation has a much lower bit-error rate than the two-step MMSE optimization scheme with quantization error compensation and the joint MMSE optimization scheme without quantization error compensation.

关键词： multi-relay precoding limited feedback minimum mean square error

Performance analysis of variable-power adaptive modulation in space-time block coded MIMO diversity systems

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science china(information sciences) 2010年第10期53卷 2106-2115页

作者： yu XiangBin 1,2 & SHI HuiBin 1 1 college of information science and technology, nanjing university of Aeronautics and Astronautics, nanjing 210016, china 2 National Mobile Communications Research Laboratory, Southeast university, nanjing 210096, china college of information science and technology Nanjing University of Aeronautics and Astronautics Nanjing China National Mobile Communications Research Laboratory Southeast University Nanjing China

In this paper, the performance analysis of multi-antenna MIMO systems with variable-power (VP) adaptive modulation and space-time coding is presented. The fading gain value is partitioned into a number of regions by which we decide the transmission power according to the region the fading gain falls in. The optimum fading gain region boundaries (switching thresholds) for maximizing spectrum efficiency (SE) under a target BER and average power constraint are derived. It is shown that the Lagrange multiplier in the constrained SE optimization will be unique if the existence condition for multi-antenna systems is satisfied, and is unique for single antenna systems. A practical iterative calculation method based on Steepest Descent Algorithm for finding the Lagrange multiplier is proposed. With the switching thresholds, the closed-form expressions of the SE and average BER, respectively for VP system and constant-power (CP) system are achieved. Simulation results for SE and average BER are in good agreement with the theory analysis. The results show that VP adaptive modulation with space-time coding provides better SE than the counterpart with CP under a target BER and average power constraint.

关键词： adaptive modulation variable power space-time block code constant power multiple input multiple output (MIMO)

Heterogeneous reaction of NO_2 with sea salt particles

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science china Chemistry 2010年第12期53卷 2652-2656页

作者： YE ChunXiang 1,li HongJun 1,ZHU Tong 1,SHANG Jing 1,ZHANG ZeFeng 1,2 & ZHAO DeFeng 1 1 State Key Joint Laboratory of Environmental Simulation and Pollution control college of Environmental sciences and Engineering,Peking university,Beijing 100871,china 2 college of Atmospheric Physics,nanjing university of information science and technology,nanjing 210044,china State Key Joint Laboratory of Environmental Simulation and Pollution control college of Environmental sciences and Engineering Peking University Beijing China college of Atmospheric Physics Nanjing University of Information Science and Technology Nanjing China

To understand how NO2 reacts with sea salt particles in the atmosphere of Mega-cities in coastal zones,the heterogeneous reaction of NO2 on the surface of wet sea salt was investigated with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and ion chromatography (IC).Kinetic measurements indicated that nitrate formation on sea salt was second order in NO 2 concentration and reactive uptake coefficients were (5.51 ± 0.19) × 10-7 and 1.26 × 10-6 respectively under 0% and 20% relative humidity (RH) at NO 2 molecular concentration of 1.96 × 1015 mol/*** results showed that liquid water was formed at the site of MgCl2·6H2O,CaCl2·2H2O on the surface of sea salt and made the reaction more sustainable by releasing hydrated water and absorbing water from air even under a low RH (30%).Therefore,pure NaCl particles should not be used to represent sea salt in studies of the heterogeneous reaction with NO2.

关键词： sea salt particles diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) hydrated water absorbed water reactive uptake coefficient

Deterministic secure quantum communication without unitary operation based on high-dimensional entanglement swapping

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science china(information sciences) 2012年第2期55卷 360-367页

作者： liU ZhiHao1,CHEN HanWu1,liU WenJie2,XU Juan1 & li ZhiQiang3 1School of Computer science and Engineering,Southeast university,nanjing 211189,china 2School of Computer and Software,nanjing university of information science & technology,nanjing 210044,china 3college of information Engineering,Yangzhou university,Yangzhou 225009,china School of Computer science and Engineering Southeast University Nanjing China School of Computer and Software Nanjing University of Information Science & Technology Nanjing China college of information Engineering Yangzhou University Yangzhou China

By analysis of the basic properties of entanglement swapping of high-dimensional Bell states,a universal and general deterministic secure quantum communication(DSQC)protocol is proposed,in which unitary operation is not *** making use of the results of high-dimensional Bell measurement,the sender and the receiver can encode and decode the message respectively by performing the modular addition and *** mutually complementary bases are constructed;and according to the property of mutual complement,a method for checking security of the high-dimensional quantum channel is put *** common attack strategies are analyzed,and the corresponding error rates are *** the upper bound of the threshold of error rate is deduced.

关键词： deterministic secure quantum communication high-dimensional Bell state entanglement swap-ping high-dimensional Bell measurement

Image space analysis for variational inequalities with cone constraints and applications to traffic equilibria

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science china Mathematics 2012年第4期55卷 851-868页

作者： li Jun 1,& HUANG nanjing 2 1 college of Mathematics and information,china West Normal university,Nanchong 637009,china 2 Department of Mathematics,Sichuan university,Chengdu 610064,china college of Mathematics and information China West Normal University Nanchong China Department of Mathematics Sichuan University Chengdu China

In this paper,the image space analysis (for short,ISA) is employed to investigate variational in- equalities (for short,VI) with cone *** separation for VI with cone constraints is characterized by using the normal cone to a regularization of the image,and saddle points of the generalized Lagrangian func- ***-type necessary and sufficient optimality conditions for VI with cone constraints are presented by using a separation *** functions and weak sharpness for VI with cone constraints are also investi- ***,the obtained results are applied to standard and time-dependent traffic equilibria introduced by Daniele,Maugeri and Oettli.

关键词： variational inequality image space analysis linear separation necessary and sufficient optimalitycondition traffic equilibrium

Further study of sources of the imported cobalt-blue pigment used on Jingdezhen porcelain from late 13 to early 15 centuries

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science china(Technological sciences) 2008年第3期51卷 249-259页

作者： DU Feng1 & SU BaoRu2 1 Institute of Chemistry & Molecular Engineering, Qingdao university of science & technology, Qingdao 266000, china 2 college of information science technology, Qingdao university of science & technology, Qingdao 266000, china Institute of Chemistry & Molecular Engineering Qingdao University of Science & Technology Qingdao China college of information science technology Qingdao University of Science & Technology Qingdao China

Based on the conclusion of modern scientific analysis: the cobalt-blue pigment applied on Jingdezhen official porcelain during yuan Dynasty and prior to Xuande reign of Ming Dynasty (1271―1425) contains high iron and low manganese con- tents, and the cobalt during Xuande and after Xuande periods (after 1426) of Ming Dynasty contains high manganese and low iron contents, in combination with the traditional archaeological method, the related historical textual records were in- vestigated and analyzed, the imported cobalt employed on Jingdezhen official porcelain was studied comprehensively, systematically and logically. In fact, 'Su Ma li Qing' (Samarra-blue) and 'Su Bo Ni Qing' (Sumatra-blue) are definitely different cobalt ores originated in different places, because of their very similar translitera- tions in Chinese, the confusion has appeared in ancient books for more than 400 years, which considered 'Su Ma li Qing' and 'Su Bo Ni Qing' as the same co- balt-blue pigment. In this article the mistake was corrected, the possible producing places and the approximate eras of the two pigments imported to china and used at Jingdezhen were also suggested.

关键词： imported cobalt-blue pigments employed on official blue-and-white porcelain yuan Dynasty early Ming Dy- nasty Mn/Fe content ratio Su Ma li Qing (Samarra-blue) Su Bo Ni Qing (Sumatra-blue) scientific archae- ological research transliteration

Quantum secret sharing between multiparty and multiparty with four states

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science china(Physics,Mechanics & Astronomy) 2007年第5期50卷 572-580页

作者： YAN Fengli1, GAO Ting2 & li YouCheng1 1 college of Physics and information Engineering, Hebei Normal university, Shijiazhuang 050016, china 2 college of Mathematics and information science, Hebei Normal university, Shijiazhuang 050016, china college of Physics and information Engineering Hebei Normal University Shijiazhuang China college of Mathematics and information science Hebei Normal University Shijiazhuang China

A protocol of quantum secret sharing between multiparty and multiparty with four states was presented. It was shown that this protocol can nullify the Trojan horse attack with a multi-photon signal, the fake-signal attack with Einstein-Podolsky- Rosen pairs, the attack with single photons, and the attack with invisible photons. In addition, the upper bounds of the average success probabilities were given for dishonest agent eavesdropping encryption using the fake-signal attack with any two-particle entangled states.

关键词： quantum secret sharing, security, Einstein-Podolsky-Rosen pairs

Research on the mechanism of the two-dimensional ultrasonic surface burnishing process to enhance the wear resistance for aluminum alloy

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Friction 2024年第3期12卷 490-509页

作者： Zhen-yu ZHOU Qiu-Yang zheng yu li Cong DING Guang-Jian PENG Zhong-yu PIAO college of Mechanical Engineering Zhejiang University of TechnologyHangzhou 310023China Key Laboratory of Special Purpose Equipment and Advanced Processing technology Ministry of Education and Zhejiang ProvinceZhejiang University of TechnologyHangzhou 310014China

The gradient nanostructure is machined on the aluminum(Al)alloy by the two-dimensional ultrasonic surface burnishing process(2D-USBP).The mechanism of why the gradient nanostructure enhances wear resistance is *** mechanical properties and microstructure characterization for the gradient nanostructure are performed by operating a nanoindenter,transmission electron microscopy(TEM),and electron backscattered diffraction(EBSD).Dry wear tests are performed on the samples before and after machining to evaluate the wear resistance and *** effect of the gradient nanostructure on the wear resistance is explored by developing the crystal plasticity(CP)finite element and molecular dynamics(MD)*** characterization results show that the 2D-USBP sample prepared a gradient structure of~600μm thick on the aluminum surface,increasing the surface hardness from 1.13 to 1.71 GPa and reducing the elastic modulus from 78.84 to 70.14 *** optimization of the surface microstructure and the increase of the mechanical properties effectively enhance the wear resistance of the sample,with 41.20%,39.07%,and 54.58% of the wear scar areas for the 2D-USBP treated samples to the original samples under 5,10,and 15 N loads,*** gradient nanostructure hinders the slip of dislocations inside the sample during the wear process and reduces the size and scope of plastic deformation;meanwhile,the resistance to deformation,adhesion,and crack initiation and propagation of the sample surface is improved,resulting in enhanced wear resistance.

关键词： structural superlubricity lattice registry elastic deformation strained solitons crystal plasticity molecular dynamics simulations