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1.
交互网格中的会话管理机制研究   总被引:1,自引:0,他引:1  
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.  相似文献   

2.
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.  相似文献   

3.
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.  相似文献   

4.
数据库连接池技术及其应用研究   总被引:5,自引:1,他引:4  
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.  相似文献   

5.
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.  相似文献   

6.
CSCW环境下多数据库的操作语言模型   总被引:2,自引:0,他引:2  
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.  相似文献   

7.
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  相似文献   

8.
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  相似文献   

9.
基于主从许可证的多级信任版权分布式安全认证协议   总被引:1,自引:0,他引:1  
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。  相似文献   

10.
基于.NET的B/S模式企业协作网信息系统的设计与实现   总被引:2,自引:0,他引:2  
采用.NET技术,以C#为语言开发工具,建立一个B/S模式的企业协作网信息系统,实现基于B/S模式的数据管理和数据维护的方法.着重介绍了系统实现中所使用的数据库交互和系统业务逻辑组件等关键技术.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
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.  相似文献   

15.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

16.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

17.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

18.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

19.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

20.
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.  相似文献   

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