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Effect of Zn^(2.) Content on the Microstructure and Magnetic Properties of Nanocrystalline Ni_(1-x)Zn_xFe_2._4 Ferrite by a Spraying-coprecipitation Method

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Journal of Wuhan university of technology(Materials {2.) 2010年第3期25卷 429-431页

作者：刘银 college of Materials science and Engineering Anhui University of Science and Technology

Nanocrystalline Ni1-xZnxFe2.4 ferrites with 0≤x≤1 were successfully prepared by a spraying-coprecipitation *** microstructure was investigated by using XRD and *** properties were measured with vibrating sample magnetometer（VSM） at room *** results show that the grain size of nanocrystalline Ni1-xZnxFe2.4 ferrite calcined at 600 ℃ for 1.5 h is about 30 *** parameter and specific saturation magnetization Ms of nanocrystalline Ni1-xZnxFe2.4 ferrite increase with the Zn^2. ions content at room temperature,and maximum Ms is 66.8 A·m^2.kg^-1 as the Zn^2. ions content is around 0.5,and coercivity Hc of the nanocrystalline Ni1-xZnxFe2.4 ferrite decreases with Zn^2. ions content.

关键词： nanocrystalline material Ni-Zn ferrite spraying-coprecipitation method magnetic properties microstructure

Influences of low-Ti substitution for La and Mg on the electrochemical and kinetic characteristics of AB_3-type hydrogen storage alloy electrodes

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science china(Technological sciences) 2010年第1期53卷 242-247页

作者： DONG ZhenWei1,2.WU YaoMing1,MA LiQun2.SHEN XiaoDong2.& WANG LiMin1 1 State Key Laboratory of Rare Earth Resource Utilization,Changchun Institute of Applied Chemistry,Chinese Academy of sciences,C hangchun 13002.,china {2. of Material science and Engineering,nanjing university of technology,nanjing 2.0009,china State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied Chemistry Chinese Academy of Sciences college of Material science and Engineering Nanjing University of Technology

The(La0.67Mg0.33)1-xTixNi2.75Co0.2.(x = 0,0.05,0.10,0.15 and 0.2.,at%) alloys were synthesized by arc melting and subsequent heat solid-liquid diffusing *** structure,electrochemical properties and kinetic characteristics of the alloys were investigated *** results showed that all the alloys mainly consisted of the(La,Mg)Ni3,LaNi5 phases,and the lattice parameters and the cell volumes of the(La,Mg)Ni3 and LaNi5 phases decreased with increasing Ti *** alloy electrodes could be activated to reach their maximum discharge capacity within five *** cycle life after 100 charge/discharge cycles(C100/Cmax) and the high-rate dischargeability at a discharge current density of 12.0 mA/g first increased and then *** the results showed that low-Ti content in AB3-type hydrogen storage alloys was beneficial to improvements of the overall electrochemical properties,and the optimum overall electrochemical performance of the alloy electrodes was obtained when x = 0.05.

关键词： AB3-type alloy metal hydride electrode microstructure electrochemical property kinetic characteristic

Preparation and Characterization of Nanocomposite MgFe_2._4/SiO_2

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Journal of Wuhan university of technology(Materials {2.) 2009年第3期24卷 354-358页

作者：徐莉 college of science Nanjing Forestry University

Nanocomposites MgFe2.4/SiO2.were successfully synthesized by the sol-gel method in the presence of N, N-dimethylformamide （DMF）. The formation of pure MgFe2.4 was confirmed by powder X-ray diffraction （XRD） and electron diffraction. The structural evolution of MgFe2.4 nanocrystals was followed by powder X-ray diffraction and IR absorption spectroscopy. The formation of spinel structure of MgFe2.4 started at 800 ℃, and completed at 900 ℃, The transmission electron microscopy （TEM） measurements suggest that the particle sizes increase with the increasing annealing temperature, and the mean particle sizes of the spherical samples annealed at 800 ℃, 900 ℃ and 1 050 ℃ are ca. 3 nm, 8 nm and 11 nm, respectively. Magnetization measurements at room temperature and 78 K indicate supemaramagnetic nature of these MgFe2.4 nanocrvstals.

关键词： nanocomposite sol-gel magnesium ferrite magnetic property

On power allocation for a cognitive radio network with hybrid spectrum sharing

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science china(Information sciences) 2011年第11期54卷 2425-2434页

作者： ZHANG Jing 1,2.3 & ZHU HongBo 1 1 Key Laboratory of Wireless Communications of jiangsu Province,nanjing {2. of Posts & Telecommunications,nanjing 2.0003,china 2.college of Electronic science & Engineering,nanjing {2. of Posts & Telecommunications,nanjing 2.0003,china 3 State Key Laboratory of Millimeter Waves,nanjing 2.0096,china Key Laboratory of Wireless Communications of jiangsu Province Nanjing University of Posts & Telecommunications college of Electronic science & Engineering Nanjing University of Posts & Telecommunications State Key Laboratory of Millimeter Waves

In this study we propose a hybrid spectrum sharing scheme based on power control by combining Overlay with Underlay schemes,to improve radio spectrum *** the scheme,the secondary users dynamically switch their operational states between Overlay and Underlay according to the spectrum *** the dynamics of the primary network is first modeled with a discrete-state Markov process to find the time fraction of secondary users in the Overlay state and that in the Underlay state,which leads to the capacity model of the hybrid spectrum sharing *** the criterion of maximizing capacity,the power allocation of the cognitive network is researched and the optimum power allocation for secondary users is *** a result,the maximum achievable capacity of the cognitive network is *** are given to prove the analysis *** and simulated results indicate that hybrid spectrum sharing based on power control provides a higher capacity than single Overlay and Underlay systems for the cognitive network,i.e.,hybrid spectrum sharing can further improve radio spectrum efficiency.

关键词： cognitive radio network hybrid spectrum sharing primary network dynamics power allocation achievable capacity

Tribological Properties of Dimpled Surface Alloying Layer on Carbon Steel

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Journal of Wuhan university of technology(Materials {2.) 2009年第2期24卷 218-222页

作者：万轶 Department of Materials science & Engineering Nanjing University of Science and Technology Department of Mechanical and Electrical Engineering Yingtian College

The effect of surface structure and coating on tribological properties of 45^# carbon steel disc was analyzed. A Nd：YAG laser was used to generate rnicrodirnples on steel surfaces. Dimples with diameter of 150 rn and depth of 50 rn were distributed in an orbicular array on disc surface. Then the alloying element Mo was sputtered to 45# carbon steel disc surface by means of double glow plasma technology. Diffusion Mo alloying layer with 30min thickness and high hardness up to 0.02. was formed on the disc surface. Tribological experiments of three types samples （smooth, texturing and texturing＋alloying） were conducted with a pin-on-disc tribometer. It is found that the dimpled-samples are most effective for reducing friction in comparison with smooth steel surthces, improving the lubricating state from boundary to hydrodynamic region.

关键词： laser surface texturing double glow plasma surface alloying technology carbon steel tribological performance lubricating state

Research into a theoretical mode of coherent structures in the wall region of a turbulent boundary layer induced by a wall local disturbance

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Progress in Natural science:Materials International 2009年第9期19卷 1119-1124页

作者： Changgen Lua,*, Qinjuan Qi b a college of Atmospheric sciences, {2. university of Information science & technology, {2. 2.0044, china b college of Public Management, {2. university of Information science & technology, {2. 2.0044, china college of Atmospheric sciences Nanjing University of Information Science & Technology Nanjing 210044 China college of Public Management Nanjing University of Information Science & Technology Nanjing 210044 China

The idea of applying direct numerical simulation (DNS), a theoretical mode of coherent structures in the wall region of a turbulent boundary layer, has been discussed in the literature. The various aspects of the formation mechanism of the coherent structures agree well with both DNS and experimental results. In addition, a close relationship has been found between the evolutional characteristics and factors such as the magnitude and structural distribution of the wall local impulse disturbance, and the amount of energy a local disturbance introduces into the wall region. Moreover, these parameters play key roles in the formation of coherent structures near the wall region of a turbulent boundary layer. Therefore, the wall local impulse disturbance provides a theoretical model for triggering the formation of coherent structures in the wall region of a turbulent boundary layer.

关键词： Turbulent boundary layer Wall region Coherent structure Local disturbance

Large Solutions to Complex Monge-Ampère Equations: Existence, Uniqueness and Asymptotics

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Chinese Annals of Mathematics,Series B 2011年第4期32卷 569-580页

作者： Ni XIANG Xiaoping YANG Faculty of Mathematics and computer science Hubei University Wuhan 430000 China School of science Nanjing University of Science and Technology Nanjing 210094 China

The authors consider the complex Monge-Ampere equation det（uij） = ψ（z, u, △↓u） in bounded strictly pseudoconvex domains Ω, subject to the singular boundary condition u =∞ on δΩ. Under suitable conditions on ψ, the existence, uniqueness and the exact asymptotic behavior of solutions Monge-Ampere equations are established to boundary blow-up problems for the complex

关键词： Complex Monge-Ampere equation Boundary blow-up Plurisubharmonic Pseudoconvex Asymptotics

The Synthetic Evaluation of Warhead Overall Efficiency

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Journal of Systems Engineering and Electronics 2003年第1期14卷 12-17页

作者： Gu Xiaohui & Cao Bing college of Mechanics, nanjing {2. of science & technology, nanjing 2.0094, P. R. china college of Mechanics Nanjing University of Science & Technology Nanjmg 210094 P. R. China

The evaluation system of smart ammunition warhead overall efficiency has been established in this paper. Allkinds of evaluation methods have been analyzed. Having led the concept of hierarchical structure into technique for orderpreference by similarity to ideal solution (TOPSIS) method, we put forward the step TOPSIS method which is suitable forevaluating the overall efficiency of smart ammunition warheads. In the calculation of index weight, the graded weight cal-culus is put forward which hardly relies on the subjectivity of decision-makers and can reflect the sensitivity and compatibili-ty of the index. In the graded weight calculation, the proportional-arithmetic weight value calculus and sensitivity-compati-bility weight value calculus are given respectively.

关键词： Step analysis TOPSIS method Warhead Efficiency evaluation.

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 {2. of Information science and technology, nanjing 2.0044, china 2.Department of Control science and Engineering, Huazhong {2. 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 Department of Control science and Engineering Huazhong University of Science and Technology Image Processing and Intelligent Control Key Laboratory of Educatio

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