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81.
GLOBAL EXPONENTIAL STABILITY IN HOPFIELD AND BIDIRECTIONAL ASSOCIATIVE MEMORY NEURAL NETWORKS WITH TIME DELAYS 总被引:1,自引:1,他引:0 下载免费PDF全文
Without assuming the boundedness, strict monotonicity and differentiability of the activation functions, the authors utilize the Lyapunov functional method to analyze the global convergence of some delayed models. For the Hopfield neural network with time delays, a new sufficient condition ensuring the existence, uniqueness and global exponential stability of the equilibrium point is derived. This criterion concerning the signs of entries in the connection matrix imposes constraints on the feedback matrix independently of the delay parameters. From a new viewpoint, the bidirectional associative memory neural network with time delays is investigated and a new global exponential stability result is given. 相似文献
82.
83.
以菲咯啉和3,5-二甲基-1-羧甲基-4-吡唑甲酸为配体,合成了2个新的配合物[Cd(Hcmdpca)2(phen)(H_2O)](1)和[Cu2(Hcmdpca)2(phen)4(NO3)2]·4H_2O(2)(H2cmdpca=3,5-二甲基-1-羧甲基-4-吡唑甲酸;phen=菲咯啉),并用红外光谱、元素分析、热重分析和X射线单晶衍射结构分析等对其进行了表征。配合物1和2都属于单斜晶系,1和2的空间群分别为C2/c和P21/c。配合物1的镉离子采取七配位的方式,Hcmdpca-阴离子桥联2个镉离子形成一个双核结构;这些双核结构单元间通过分子间氢键及π-π相互作用构成一个三维的超分子结构。配合物2是一个由2个分立的单核铜配阳离子构成的独立单元,铜离子位于一个畸变的八面体构型中;这些单核铜配阳离子和硝酸根通过静电引力和分子间氢键作用,进一步形成一个三维的超分子结构,而溶剂水分子填充在该结构的空隙中。此外还考察了1和2的热稳定性和固体荧光性质。 相似文献
84.
合成和表征了2个吡唑-3-甲酸过渡金属配合物[Cu2(pca)2(H2O)6]·2H2O(1),[Mn(Hpca)2(phen)]·3H2O(2)(H2pca=吡唑-3-甲酸;phen=菲咯啉)。X射线单晶衍射分析结果表明,配合物1属于单斜晶系P21/n空间群,它是一个畸变八面体的双核铜配合物;配合物2是一个畸变八面体的单核锰配合物。配合物1和2分别通过分子间的O-H…O,N-H…O氢键形成了三维网状结构。配合物1在二氧化碳的环加成反应中显示出了良好的催化效率(转化率高达97.4%;选择性高达98.9%)。 相似文献
85.
The sodium chlorite–iodine–ethyl acetoacetate (EAA) chemical oscillatory reaction system was studied by UV–Vis and online
FTIR spectrophotometric method. The oscillation phenomenon does not occur as long as the reactants are mixed. There is a pre-oscillatory
or induction period. The amplitude is small at the beginning stage and then increases with reaction time. Finally, the oscillation
ceases suddenly. The amplitude and the number of oscillations are associated with the initial concentration of sodium chlorite,
iodine, EAA and sulfuric acid. The equations for the triiodide ion reaction rate changing with reaction time and the initial
concentrations on the oscillation stage were obtained. The intermediates were detected by the online FTIR analysis. Based
upon the experimental data in this work and in the literature, a plausible reaction mechanism was proposed for the oscillation
reaction. 相似文献
86.
Metal-organic polyhedra represent a unique class of functional molecular containers that display interesting molecular recognition properties and fascinating reactivity reminiscent of the natural enzymes. By incorporating a triphenylamine moiety as a bright blue emitter, a robust cerium-based tetrahedron was developed as a luminescent detector of nitronyl nitroxide (PTIO), a specific spin-labeling nitric oxide (NO) trapper. The tetrahedron encapsulates molecules of NO and PTIO within the cavity to prompt the spin-trapping reaction and transforms the normal EPR responses into a more sensitively luminescent signaling system with the limit of detection improved to 5 nM. Twelve-fold amide groups are also functionalized within the tetrahedron to modify the hydrophilic/lipophilic environment, ensuring the successful application of biological imaging in living cells. 相似文献
87.
一类具有非局部扩散的时滞Lotka-Volterra竞争模型的行波解 总被引:1,自引:0,他引:1
本文研究一类具有非局部扩散的时滞Lotka-Volterra竞争模型{(δ)/(δ)t u1(x,t)=d1 [(J1*u1)(x,t)-u1(x,t)]+r1u1(x,t)[1 - a1u1(x,t)- b1u1(x,t-Τ1)-c1u2(x,t-Τ2)],(δ)/(δ)tu2(x,t)=d2[(J2*u2)(x,t)-u2(x,t)]+r2u2(x,t)[1 - a2u2(x,t)- b2u2(x,t -Τ3)-c2u1(x,t-Τ4)]行波解的存在性问题.通过利用交叉迭代技巧,我们可以把行波解的存在性转化为寻找一对适当的上下解,这篇文章中的结果推广了已有的一些结果. 相似文献
88.
Zhen Chen Huan Meng Hui Yuan Gengmei Xing Chunying Chen Feng Zhao Yun Wang Chengcheng Zhang Yuliang Zhao 《Journal of Radioanalytical and Nuclear Chemistry》2007,272(3):599-603
Nanosized copper particles are widely used in fields of lubricants, polymers/plastic, metallic coating and ink. Recently,
we found that copper particles in different sizes can lead to different toxicological effects. To clarify the target organs
of copper particles of different sizes, the inductively coupled plasma mass spectroscopy (ICP-MS) was employed to evaluate
the distribution of copper in different organs of mice after a single dose oral exposure. The results suggest that the main
target organs for copper nanoparticles are kidney, liver and blood. Liver is the main damaged organ. 相似文献
89.
In physicochemical studies on the sea-surface microlayer (SML) in seawater, the main researches conducted were as follows:
(1) It was found that there is an objective layer of sudden change in physical and chemical properties between the SML and
the subsurface layer in seawater. (2) The SML thickness was determined and should be about 50±10 μm. (3) The Gibbs model of
the SML was extended, and the multilayer model of the SML was advanced. (4) The original-location method, which corresponds
with the traditional removal-location method, was founded and used to determine the SML thickness. The results obtained from
the two methods were almost identical. (5) An abnormal phenomenon was found when the Gibbs solution adsorption was applied
to the seawater system, the reason for which was discussed preliminarily. 相似文献
90.
就现代空中交通管理中地面等待策略 (GDP)的发展和现状作了简要的总结概括 ,阐述了地面等待对空中交通流量管理的影响与意义 ,分类分析了地面等待策略 ,同时从众多理论研究中归纳出了几种典型模型和求解方法 ,并对各种模型、方法进行了比较分析 ,最后提出了地面等待策略的发展趋势和方向 . 相似文献