含时滞的Hopfield网络模型的全局指数稳定性

本文研究了具有变时滞的细胞神经网络系统·xi(t)=-cixi(t) n∑j=1αijfj(xj(t)) n∑j=1bijfj(xj(t-τj)) Ii,i=1,2,…,n.在非线性神经激励函数是Lipschitz条件下,通过引入Lyapunov函数,用不等式等方法,得到了该系统的平衡点是全局指数稳定的条件.     

变时滞细胞神经网络模型的全局指数稳定性

研究了具有变时滞的细胞神经网络系统nx.i（t）=-cixi（t）＋∑nj=1aijfj（xj（t））＋∑nj=1bijfj（xj（t-τj（t）））＋Ii,i=1,2,…,n.在非线性神经激励函数满足Lipschitz条件下,借助于推广的Halanay时滞微分不等式等方法,得到了该系统的平衡点是全局指数稳定的条件.     

时滞细胞神经网络模型的全局吸引性和全局指数稳定性

借助于Liapunov第二方法 ,对具有时滞的细胞神经网络系统x′i(t) =-Cixi(t) ∑nj=1aijfj(xj(t) ) ∑nj=1bijfj(xj(t-τj) ) Ii,　i=1,2 ,… ,n ,在非线性神经元激励函数满足Lipschitz连续的条件下 ,研究了这类模型全局吸引和平衡点全局指数稳定的问题 ,获得了易于验证的充分条件     

时滞细胞神经网络模型的渐近性态分析

对具有时滞的神经网络模型xi(t)=-Cixi(t) ∑j=1^n aijfj(xj(t)) ∑j=1^n bijfj(xj(t-τj)) Ii,i=1,2,…,n,在非线性神经元激励函数满足Lipachitz连续的条件下通过构造适当的泛函，研究了这类模型的渐近性态，获得了这类模型全局吸引和平衡点的全局指数稳定易于验证的充分条件．     

二阶线性非自治时滞微分方程的稳定性

研究了非自治时滞微分方程x′i(t) ∑2j= 1aij(t)xj(hij(t))= 0,t≥0,i= 1,2平衡点(x1,x2)T = (0,0)T 的稳定性,应用Liapunov 泛函方法得到该系统稳定性的条件.这些检验方程对于进一步研究数值方法中的稳定性提供了理论基础.     

Hopfield型时滞神经网络模型的K-稳定性

研究具有时滞的Hopfield型神经网络模型｛Cidui(t)/dt=-ui(t)/Ri n↑∑↑j=1～↑Tijfi(uj(t-τ）） Ii，ui（s）=ψi(s),s∈[-τ，0],i=1,2,…，n平衡点的K－全局渐近稳定性与K－全局指数稳定性，通过使用不等式分析技巧和微分方程性质，得到了这类模型K－稳定性的易于验证的时滞相关充分条件，并举例验证其有效性。     

多时滞一阶非线性微分方程组的振动性及其应用

讨论多时滞一阶非线性微分方程组dxi(t)/dt mΣj=1aij(t)fij(xj(t-τj(t)))=0,i=1,2,…,m. 的所有解振动的充分条件.同时我们也得到了多时滞LOGISTIC方程组dNi(t)/dt=Ni(t)[ai-mΣj=1bijNj(t-τj)],i=1,2,…,m.的所有正解关于它的平衡点振动的充分条件.     

一类复杂动力学网络的滑模控制混沌同步

滑模控制作为一种重要的鲁棒控制策略,得到广泛的应用,运用滑模控制实现多个具有相互关联的混沌系统的同步问题还鲜有报道。本文利用滑模控制方法研究了一类复杂动力学网络的同步控制问题,该系统的驱动系统为i=Cxi+1+f(xi+1),n=g(x1,x2,…,xn),而响应系统为j i=Cxj i+1+f(xj i+1),j n=g(xj1,xj2,…,xj n)+ξj+uj,结果表明选取适当的滑模面和控制律,该混沌系统是同步的。文章基于Lyapunov稳定性理论,设计了网络滑模面以及控制输入,如果选取适当的可调参数,可得到V·<0,从而在滑模控制方法下多个混沌系统构成的复杂动力学网络是混沌同步的,仿真算例说明了该方法的有效性。     

线性模型下分布函数的估计

利用辅助信息,针对线性模型yi=βxi xi^yεi,εi i.i.d,Fεi=0,给出了总体分布函数的估计量：F（t)=1/N[∑j∈iΔ(t-yi) ∑j∈,1/n∑j∈Δ（t-β^*xi-xi^yuj)],uj=(yj-β^*xj)/xjy^*,j∈s,改进了Chambers-Dunstan的结果。     

广义时延神经网络的渐近稳定性

讨论如下带有时延的广义神经网络模型(dxi)/(dt)=Gi(xi)[bi(xi)-∑nj=1cijdj(xj(t-τj))], i=1,2,...,n,其中,τj＞0为第j个神经元的时延,cij表示第j个神经元在t-τj时刻的输出对第i个神经元的影响强度,t∈I=[t0,∞),x∈Rn.利用Lyapunov函数及推广的Halanay微分不等式,研究了该模型的渐近稳定性,给出了系统指数稳定的几个充分条件及相应的Lyapunov指数.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

<正>~~     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to