交互网格中的会话管理机制研究

区别于传统的计算网格和数据网格,交互网格是未来网格应用发展的一个重要方面.分析了交互网格中协作应用的特点;提出了一种交互网格中的会话管理框架,通过会话管理支持网格中各种异构资源之间的协同交互;采用面向服务的架构实现了一个会话管理原型,并对其总体特性进行了评价.实验表明该系统能支持基于网格的协同应用.     

超媒体系统模型NEXTER

介绍一种新型的基于客户／服务器的超媒体模型─—ＮＥＸＴＥＲ的总体结构及其实现方法．该模型的主要优点是方便在网络上实现分布式的超媒体系统，以及简化在已有的超媒体系统中增加新媒体类型的手续．基于ＮＥＸＴＥＲ模型的超媒体系统工作在一个数据库系统之上，由４类服务器组成，其中，会话服务器管理对超媒体的游览，媒体服务器处理对各种媒体形式的内部数据，环境服务器向用户提供了界面，而超媒体数据库管理系统管理超媒体数据库．     

数据库连接池技术及其应用研究

在基于JDBC的数据库应用开发中,数据库连接的管理是决定该应用性能的一个重要因素．在对数据库连接进行分析的基础上,提出了一种合理、有效的数据库连接池的设计与实现方案．实际运行的结果表明,它能大大改善系统响应时间,降低系统资源的开销,从而提升系统整体性能,满足大型应用的需要．     

基于数据库的WEB程序开发中连接池的设计与实现

在对传统数据库连接模式分析的基础上,采用一种基于数据库的连接池技术,通过在连接对象中放置预先建立的若干“连接”,并按照一定的策略有效管理这些“连接”,利用JAVA语言实现该方案,旨在提供一个高效的数据库连接管理策略,提高WEB数据库应用系统的性能.     

海量数据库的查询优化研究及实现

本文通过对现有海量数据现状的研究，找出了影响海量数据库查询的瓶颈所在．并结合电信、银行等大型企业的实际硬件背景，提出了一种基于数据库文件分段的海量数据库查询优化策略，并对其进行了实现．实验结果表明此海量数据库查询的优化方案，能明显的改进海量数据库的查询性能，具有较高的现实意义．     

CSCW环境下多数据库的操作语言模型

基于多数据库面向用户交互操作的特点,分析了ＣＳＣＷ环境下多数据库的多态性、自治性及分布性,提出了ＣＳＣＷ环境下对多个数据库的操作模型,以及用户对多数据库操作的语句模型及其实现策略,并进行了计算机模拟实现．结果表明,ＣＳＣＷ环境下对多个数据库的操作语言模型具有较好的性能．     

移动ATM网络动态移动管理策略

由于移动多媒体应用的呼叫连接到达率的变化范围较广，与移动电话用户具有不同的特性，对其有效的支持关系到移动管理信令量、数据库访问业务量及移动呼叫连接建立时延等网络性能．针对这一情况，提出了考虑主机的移动特性、访问模式和被访问模式的多媒体移动ＡＴＭ动态移动管理策略，给出了访问指针层次算法，并对其性能进行了仿真分析．该策略对访问指针更新代价和移动定位代价进行折衷，优化了整个网络的移动管理代价，具有较强的适应性和可扩展性     

移动ATM网络动态移动管理策略

由于移动多媒体应用的呼叫连接到达率的变化范围较广，与移动电话用户具有不同的特性，对其有效的支持关系到移动管理信令量、数据库访问业务量及移动呼叫连接建立时延等网络性能．针对这一情况，提出了考虑主机的移动特性、访问模式和被访问模式的多媒体移动ＡＴＭ动态移动管理策略，给出了访问指针层次算法，并对其性能进行了仿真分析．该策略对访问指针更新代价和移动定位代价进行折衷，优化了整个网络的移动管理代价，具有较强的适应性和可扩展性     

基于对象存储系统的对象文件系统设计

基于对象文件系统是建立在对象存储系统上的一种应用，它利用对象的特点对数据进行存储和管理．基于对象文件系统由客户端、元数据服务器和基于对象存储设备组成，通过对系统的各部分进行分析，设计并实现了基于对象文件系统．通过对不同文件大小、不同文件分块大小条件下文件系统的性能进行测试分析，找出系统的数据传输瓶颈，使用以对象属性为导向的缓存和预取技术以及聚合读写的方法对文件系统进行了优化．优化后读写吞吐率分别提高了60Mbyte／s和40Mbyte／s。     

基于主从许可证的多级信任版权分布式安全认证协议

为了解决当前软件版权保护措施在安全性有效性方面存在的问题，基于第三方可信中心提出了一种主从动态许可证支持的多级信任版权安全许可协议(M-CPSec)，通过特征关联、原子授权、强制收权和多级分发机制，有效地解决了软件版权的安全保护、软件资源的任意迁移、软件内容的完整保持和版权的多级分发问题．这种层次化多级版权控制结构构成一种信任传递关系，使得协议普遍适用于单用户和带有多用户的客户服务器软件版权保护．协议交互中通过数据加密和数字签名来保证分布式环境下数据的安全性、完整性以及不可否认性．协议分析证明了所提方案的可行性、安全性以及完备性．M-CPSec方案以支持客户服务器版权管理而扩展了最终用户许可协议，为软件版权保护提供了一种普遍适用的方案。     

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.     

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.     

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).     

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.