基于扩展角色访问控制模型的应用研究

针对传统的RBAC模型的不足,对角色权限及角色层次关系进行了分析,提出了一个改进的角色访问控制模型-ERBAC。应用实例说明,新模型在描述同样的角色关系时角色数量比传统模型要少,因而比传统模型更加简化和直观,特别适合于管理信息系统的应用。     

基于RBAC改进模型的角色权限及层次关系分析

针对著名的RBAC96模型的不足之处,结合私有权限、部门权限和权限属性变化等问题,对角色权限及角色层次关系进行了分析,提出了一个改进的角色层次化关系模型.该模型引入特征权限等概念,通过定义一般继承、私有化继承、公有化继承和无特征继承等新的角色继承方式建立角色层次化关系模型.新模型比RBAC96模型更加简化和易于理解,且具有更强的可伸缩性,特别适合于在复杂的角色层次关系中应用,例如网络操作系统、大型数据库、分布式应用等.     

一种新的基于角色的访问控制模型

文章提出了一种新的基于RBAC的角色层次控制与用户业务限制混合权限管理模型(N-RBAC),定义了角色的共有权限、基于层次控制的角色影子权限以及用户的私有业务约束;该模型比传统的RBAC或其修正模型具有更高的灵活性和更广的适用性,解决了角色与用户之间共性与个性的矛盾,既简化了信息系统中对用户授权管理,又使相同角色的用户对相同的功能模块可以有不同的操作限制;详细讨论了N-RBAC的设计原理与实现方法;应用实践表明该模型使用方便,设置灵活,能有效满足各类信息系统权限管理的需要。     

基于RBAC的用户权限管理的设计与实现

针对传统RBAC模型在权限控制中的不足,提出一种基于角色的用户权限管理模型,并阐述了此模型的原理、数据库设计以及在ASP.NET 3.5平台上实现的具体方法。该模型在原RBAC模式的基础上,在用户和角色之间引入部门这一对象,通过角色、部门对功能进行分组,再通过用户和角色、用户和部门的关系,抽象出用户与功能的关系,从而增加权限配置的粒度。此方案已经在北京金融街电子政务系统中得到应用,结果表明这种权限管理方法不但提高了管理系统的适用性和安全性,而且让信息系统的维护和扩展也变得方便和容易。     

基于角色的访问控制理论研究

主要进行信息系统安全中基于角色的访问控制理论研究。首先对角色的关系进行扩展。引入了扩展角色、主体角色继承和扩展主体角色继承层次等概念，并证明了扩展主体角色继承具有偏序关系性质；然后对基于角色的访问控制模型进行扩展，引入客体角色概念，并给出了扩展客体角色的继承层次关系是一偏序关系的证明。为建立类似于传统RBAC（基于角色的访问控制模型）结构的新系统提供了手段。特别是在网格计算环境中存在着虚拟组织结构和跨域认证与操作，采用扩展角色与角色控制域概念可以体现这样的特征，为深入研究网格环境下的安全访问控制理论打下基础。最后讨论了进一步研究的问题。     

基于角色访问控制的权限管理系统改进与应用

对基于角色的访问控制模型进行了研究,对传统访问控制模型、基于角色的访问控制（RBAC）模型、角色管理模型ARBAC97进行了描述和分析。对RBAC模型进行范围扩展,通过引入角色范围的概念,以（用户,角色,范围）三元组来标识系统用户的权限,解决RBAC模型无法对资源实例进行权限控制的问题,也就是解决了系统用户拥有相同的角色,操作的数据范围可以不同。结合实际应用系统的需求,实现了权限管理系统。     

基于客体管理的增强型RBAC模型的研究

提出了一种基于客体管理的增强型RBAC模型。该增强模型将角色思想应用于处于客体位置的目标和操作,在原有模型的基础上添加了目标角色和操作角色2个元素,相应地也增加了操作与操作角色、目标与目标角色及操作角色与目标角色的关系。对新添加的角色引入层次继承关系,对新添加的关系引入静态约束,并给出了增强模型的形式化描述。     

考虑引导作用的人群应急疏散模拟研究

传统的社会力模型只能反映空间布局和人群密度对疏散过程的作用。引导角色的配置对于人群疏散过程影响显著,如果不能考虑到这种因素,就很难反映真实情况。文中在传统社会力模型的基础上进行优化改进,引入人员个体间的交互作用,能反映疏散引导角色的作用。在此理论模型基础上,进行仿真开发和仿真试验。仿真结果显示,本模型比传统社会力模型更合理,且具有更高的可信性。     

基于角色和活动的数字校园访问控制模型

为建立动态、灵活、高效的访问控制模型,针对建设高校校级统一信息系统时角色访问控制(RBAC)模型的不足,引入参与、动作与活动等概念对基于角色的访问控制模型进行扩展,提出基于角色与活动访问控制(R-ABAC)模型的模型结构、组件关系及框架结构.应用结果表明:该模型可准确地描述教学、科研、管理、服务各种活动中的授权关系,并较好地适应信息集成阶段数字校园身份与权限管理的需求.     

基于粒逻辑的扩展RBAC模型

RBAC作为一种有效的访问控制模型已被广泛地研究和应用,但传统的RBAC模型没有考虑时间和上下文因素,角色之间、权限之间的逻辑关系比较简单,以至于在拥有大量用户和角色的系统的授权中表现出效率低、管理复杂等不足.为了解决以上问题.将粒计算的思想引入到RBAC模型中,提出了基于粒逻辑的G-RBAC模型,该模型将权限、角色粒化,在权限粒和角色粒上加入了时间和上下文的因素;基于粒逻辑,定义了G-RBAC模型中各元素间的逻辑运算,实现了G-RBAC的授权推理决策,提高了授权的灵活性.应用实例表明,G-RBAC模型能有效地实现大型系统的细粒度访问控制.     

Markedness and its Interpretation in Language Use

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

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.     

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.     

Design and analysis of generic LBS application developing platform

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.     

橡胶颗粒沥青混合料低温抗裂性试验研究

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.     

A computer generator for randomly layered structures

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

低渗透非均质砂岩油藏启动压力梯度研究

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。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

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.     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.