Koblitz型超椭圆曲线Jacobian阶的计算

超椭圆曲线密码体制是基于超椭圆曲线上的离散对数问题的困难性而建立起来的.由于Koblitz型超椭圆曲线Jacobian群中有快速的群运算,因此这类曲线常被用来实现在带宽和存储受限的环境中的数字签名和身份认证.本文基于牛顿公式提出了一个快速计算Koblitz型超椭圆曲线Jacobian的阶的新方法,该方法不需分解多项式或去求多项式的根,可以快速实现.这为寻找安全的超椭圆曲线提供了新的方法.     

具临界Sobolev指数的半线性椭圆系统的非平凡解

讨论了具临界 Sobolev指数的半线性椭圆系统的非平凡解的存在性 .通过使用没有 (PS)条件的极小极大定理 ,以及对最佳 Sobolev嵌入常数的详细分析 ,得到了一些具临界 Sobolev指数的半线性椭圆系统的真正非平凡解的存在性 ,并讨论了解的一些性质     

面向安全椭圆曲线参数的 PSO优化选择

由于椭圆曲线密码体制具有长度小、安全性高的特性，因此，椭圆曲线在安全保密方面得到了广泛的应用。椭圆曲线参数的选取会影响椭圆曲线的难解程度，从而影响到系统的安全性。本文主要通过 PSO 粒子群算法查找函数最优解的方法来优化选择椭圆曲线的参数，从而得到安全的椭圆曲线，实验表明该粒子群算法具有很强的实用性。     

一类超二次退化椭圆方程非平凡解的存在性

为获得退化椭圆方程在超二次条件下非平凡解的存在性,利用紧自伴算子的谱理论,研究退化椭圆方程对应特征值问题,给出特征值和对应的特征函数的性态;根据微分方程中的变分方法,建立退化椭圆方程对应的变分结构,利用临界点理论中的局部环绕定理,获得了一些新的可解性条件,统一和推广了已有文献的一些结果.     

“椭圆曲线有理点问题研究”年度报告

在该计划第一年,我们按照年度计划,在理论基础准备部分取得相当进展。其中我们在椭圆曲线算术、同余数及千禧问题BSD猜想上取得重要成果。我们利用现代数论、算术代数几何、表示论、自守形式的系列结果,证明了对任意给定的正整数k,存在无穷多个没有平方因子的恰巧有k个奇素因子的同余数,并发展了系列新的方法工具(如二次扭转欧拉系)。这些成果有助于我们更加深入地理解椭圆曲线的算术理论,并为下一步研究提供了充足的理论基础和方法准备。另外我们在解析数论、密码编码相关问题上取得一定进展,改进了Green-Tao关于F_2~n和集的一个结果。而且,在代数簇有理点,Brauer群方面取得系列进展,利用Brauer-Manin障碍技术给出了虚二次数域平方和问题的充要条件。另外,在椭圆曲线、代数簇有理点、自守形式、p-adic分析以及经典数论等其他的基础准备方面均取得一定的进展。     

关于Steinhaus的一个问题

目的研究Steinhaus的一个问题。方法利用椭圆曲线上的有理点以及同余数的相关信息。结果得到一些Steinhaus点不存在的命题,提出两个Steinhaus猜想。结论所获命题与猜想,提供了研究Steihaus问题的一个思路,尚待更好的思路和工具方能取得更深入的结果。     

一类可分解的有限群

可以分解为2个子群乘积的有限群是有限群研究的重要课题,有不少作者进行了这方面的研究,也得到了一些重要的结论和应用.目的是继续这方面的研究.通过对某些已有结果及采用的方法的分析,借助于推广了的引理,证明了这些结论在足够弱的条件下仍然成立.特别地,给出了一个可以分解为2个子群乘积的有限群的2-幂零性、可解性、超可解性等新的判别条件,改进了某些相关结果.     

一类四阶椭圆型方程解的存在性

研究了一类四阶椭圆型方程解的存在性,在对非线性项作新的假设条件下,通过山路引理得到了四阶椭圆方程的一个非平凡解的存在性结果。     

基于椭圆曲线密码体制的(t,n)门限群签名方案

针对网络通信中很多门限群签名协议存在不具备不可冒充性、追查签名成员方法复杂及稳定性差等问题,提出了一个基于椭圆曲线密码体制的门限群签名方案,并对其进行了安全性分析. 该方案具有如下特点:通过引入成员的真实身份、化名及参与签名者的化名集合,使得方案具有不可冒充性和可追查性,且实现方式较为简洁;通过间接分配群私钥,能够方便添加和注销群成员,只需更新一些公开参数;方案基于椭圆曲线密码体制,具有密钥长度短、运算开销小的优点.     

一类Q-曲线的构造

Gross构造了一类带复乘的椭圆曲线.这类曲线是一种被称为Q-曲线的椭圆曲线.利用其特性,Gross计算了该曲线的某些Selmer群,并进而给出了关于其有理点的阶的一些信息.在本文中,我们给出这类Q-曲线的另外一种构造方式.我们的方法说明这一类Q-曲线由其某些有限阶点的算术性质所唯一确定.     

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

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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