数据库安全代理系统的设计探讨

由于对数据库的入侵行为频繁的发生,关于数据库的安全技术成为信息安全研究的焦点,采用入侵防御技术来保护数据库是一种非常有效的安全措施.本文主要对于数据库安全代理系统的设计进行探讨,重点对于代理模块和系统安全模块的设计进行论述,对于今后数据库安全设计具有一定帮助.     

数据库安全技术策略与多级安全代理模型

分析了当前数据库安全技术对操作系统、密码验证身份认证的完全依赖性和加密解密的时间代价的三种不足,从系统、数据、用户、数据库管理者、应用程序开发者的安全性进行论证,提出了解决安全威胁的策略,从而建立了数据库安全模型——多级安全代理模型。     

构建在Oracle系统成分上的数据库维护管理分析

本文主要对构建在Oracle系统成分上的数据库维护管理进行了分析。文章概述了Oracle数据库的特性，分析了当前数据库安全的现状，进而研究了Oracle系统数据库的维护管理。     

AES算法的改进用法及其在数据库加密中的应用

针对Internet环境中越来越突出的泄密、篡改和伪造等数据库安全问题，在分析比较实现数据库安全的被动与主动方法的基础上，提出了提高数据库安全性的数据库加密策略，根据数据库加密的特点，改进了AES算法的用法，并应用于一个对信息保密有较高要求的实际数据库中，取得了较好的效果。     

现代信息技术下数据库的安全性研究

数据库技术是应用最广泛的一门计算机技术它的安全越来越重要,该文从数据库安全的定义入手对用户认证存取控制安全管理和数据库加密等数据库安全技术的几个方面进行了讨论.并对国内目前采用改造数据库的方式来提高数据库安全的几个主要应用进行了详尽的阐述,最后指出了数据库安全现存的问题和将来研究的方向.     

基于WEB数据库访问连接技术的安全策略研究

本文论述了Web数据库常用访问连接技术，井在此基础上讨论了Web数据库系统面临的安全威胁，简要研究了Web数据库安全管理策略。     

办公自动化系统的设计与安全策略研究

在综合分析了LotusDomino/Notes安全机制的基础上,介绍了办公自动化(OfficeAutomation(OA))系统的总体规划设计与数据库安全策略的实现.从软件工程的角度出发,对OA系统的数据库前期需求分析、概要设计进行了详细介绍,并由此给出一套完整的OA系统数据库间的数据交换模型.     

关于SQL Server数据库的安全问题的思考

在分析数据库安全机制的基础上,讨论分析了SQL SERVER数据库使用中的安全问题,针对不同的用户分析了可能存在的安全问题,并提出了一些具体的解决方法和建议,从而提高用户对数据库安全防范意识。     

房地产数字化管理信息系统的设计与实现

对房地产管理数字化应用的现状进行了分析,指出了存在的问题和解决方法,并在商用GIS软件Arc GIS的基础上设计了可用于房地产数字化管理的应用系统．对房地产管理信息系统的体系结构、一体化空间数据库的构成以及系统实现过程中采用的关键技术进行了介绍。     

SQL Server2005的数据库安全管理

SQL Server2005是当今应用最为广泛的关系型数据库管理系统，采用何种安全保护措施，保证数据库安全，阻止对数据库的非授权访问是其须重视的问题。本文介绍了SQLServer2005所采用的多级安全机制，分析其特点及作用。     

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…     

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。     

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     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

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.     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.