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1.
为了改进传统网格的可扩展性和动态性,提出了一种集成P2P模式的网格资源管理模型,该模型融合了网格计算和对等计算的优点.基于该模型,文中分析了一种集成P2P模式的网格体系结构,并利用Pi-演算可用于对并发和动态变化的系统进行建模的特性,对该体系结构进行描述和建模,分析了有关性能,验证了模型的有效性.结果表明,基于Pi-演算的集成P2P模式的网格形式化系统能够有效地满足网格节点的服务需求.  相似文献   

2.
UML是一种得到广泛应用的系统建模语言,但是由于它缺乏形式化语义和严格的推理机制,从而影响了系统建模的准确性和开发效率。TCOZ是一种将Object—Z和TCSP相结合的形式化语言,具有丰富的建模能力。基于TCOZ,本文建立了UML视图的一种形式化模型,对类图和协作图等提出了转换规则,使得TCOZ中的推理可用于分析UML视图。通过某学校信息系统的实例,阐述了UML视图的形式化建模方法和分析技术。  相似文献   

3.
从系统工程的角度出发,基于形式化理论,对安全苛求系统的开发方法进行了研究.首先介绍了安全苛求系统的形式化方法,分析了形式化方法对安全苛求系统的作用;提出了一种安全苛求系统的形式化开发模型(FDM),给出了具体的应用实例.  相似文献   

4.
针对基于构件的软件开发如何与面向对象方法有效结合,设计并实现高度灵活、可复用的构件式应用程序,从而实现软件分析、设计与实现的连续性与一致性问题,提出了基于三层Client/Server模式的构件服务模型,研究了从OOA&OOD模型建立应用程序的构件服务模型的方法,同时给出了形式化的构件服务模型描述,这不仅为构件服务模型的形式化验证方法提供了新的研究思路,也为基于构件的软件开发提供了基础。文中的方法已成功用于实际的项目开发中,且取得了较好效果。  相似文献   

5.
针对用户呼叫层和分组层的不同运行机制,建立了认知无线电网络呼叫层和分组层相互关系的跨层马尔可夫模型,推导了次用户的呼叫阻塞概率和分组时延的表达式,提出了一种基于跨层建模的随机频谱接入新机制,并对认知无线电网络进行了系统级仿真.结果表明,文中模型能够准确地评估认知无线电网络的性能,随机频谱接入新机制可同时保证次用户呼叫层和分组层的性能要求.  相似文献   

6.
一种基于QoS约束的Web服务选择和排序模型   总被引:10,自引:0,他引:10  
提出了一种基于QoS约束的Web服务选择和排序模型,在研究Web服务的三维QoS模型的基础上设计基于QoS约束的服务选择模型,进一步研究服务效能的概念和量化方法并设计基于服务效能的排序模型.该模型的原型系统已经在国家地质调查网格中得到应用,结果表明模型能够有效保障用户对服务的需求,具有很高的查准率、响应率以及较好的负载均衡能力,提高了基于面向服务架构(SOA)的网络应用的可用性.  相似文献   

7.
系统可生存性是网络安全研究的一个新方向,通过对系统可生存性进行评估,可不断完善系统体系结构,从而提高系统可生存能力.针对系统可生存性的量化问题,在深入研究现有的主要可生存性评估方法基础上,提出了系统可生存性的动态量化评估模型SQEM(Survivability Quantitative Evaluation Model),并对系统可生存性进行了形式化定义和数学解析.在SQEM模型中,引入了系统状态转移概率和动态设置指标权重的思想,使评估的准确性得到了提高.通过实例分析,证明了SQEM的可行性和有效性.  相似文献   

8.
针对软件即服务(SaaS)流程的个性化配置需求,引入特征元代数结构来描述软件的非功能特性,通过把Pi演算进行语法扩展(EPi),对软件的功能属性和非功能属性进行形式化描述,由用户需求驱动软件服务流程演化.基于EPi提出SaaS的流程形式化描述和转换方法,建立了SaaS流程演化模型(SSFM)及服务流程演化操作规则,并用量化互模拟理论对流程演化响应需求的情况进行分析,通过建立互模拟程度空间关系量化服务流程演化前后的近似程度.  相似文献   

9.
基于Petri网的构件组装模型   总被引:1,自引:1,他引:0  
针对形式化语义对构件组装和演化描述能力不足的问题,提出了基于Petri网的构件组装模型.以Petri网系统表示构件的静态组装结构,用网中标识在库所中的流动来模拟构件的动态运行过程;构造了6种具有普遍适应性的构件组装运算,给出了构件Petri网的动态运行规则,并通过案例演示了构件Petri网的演化和组装运算过程.为了支持对构件演化过程中波及效应的量化分析,从可达标识图中抽象出构件影响因子用来描述相关构件耦合度的大小,并用以度量构件系统演化时的影响度.该模型可应用于基于构件的软件系统的体系结构描述及构造过程的演化分析.  相似文献   

10.
可用性语义Web服务的通用发现机制   总被引:6,自引:2,他引:4  
针对复杂组合Web服务的选择问题,提出了一种基于可用性的语义Web服务发现方法.使用动态自适应模板来寻找可用的组合Web服务,结合语义匹配度量化Web服务的功能、非功能属性,在形式化定义组合Web服务的可用性等规则的情况下,基于可用性的量化值进行排序,从而得到最合适的Web服务.将以建议规则实现的匹配引擎运行于原型系统,结果表明所提方法可以实时选择复杂组合Web服务,适用范围也比较大,并在查全率的基础上能够获得最优解.  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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