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。     

档案信息管理系统权限管理设计

访问控制是信息系统中进行资源安全控制和管理不可缺少的一个部分.根据档案管理系统需求,针对基于角色的访问控制方法权限控制粒度较粗的现象,对其模型进一步扩展和延伸,可以实现档案管理系统中的功能权限和数据权限的集中处理,有效防止非法用户进入系统及合法用户对系统资源的非法使用.     

基于安全域的信息系统访问控制模型研究

本文通过对企业信息系统中基于角色的访问控制模型（RBAC,Role Based Access Control）的原理及优劣势分析,阐述一种新型的、基于安全域的访问控制模型。该模型在继承了RBAC模型通过角色简化权限访问控制过程的方法基础上,进一步细分操作对象和操作方式,将角色和操作方式封装为可被操作对象复用的安全域,以进一步降低权限管理复杂度。     

基于树型角色的访问控制策略及其实现

对于工作职能耦合度高、业务呈交叉状的企业,传统的基于用户或角色的访问控制(RBAC)策略已难以实现信息系统的权限管理．文中结合RBAC的基本思想,提出了一种分层的树型角色访问控制(TRBAC)模型,并在应用程序层实现了基于角色的权限管理方案,实践表明,TRBAC简化了用户、角色和许可三者之间的配置规则,方便了系统的授权管理．     

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。     

一种基于用户角色-权限分级的访问控制模型

针对多用户系统的管理，结合RBAC模型，提出了一种基于两层分级(角色分级、权限分级)的用户模型和访问控制模型，分析了其设计和实现。以高校学生工作为例，依据角色把相关用户分为四级，在角色分级的基础上进行权限分级，提出了一种新的访问控制机制，使得实际岗位角色对应地映射到应用系统中。     

RBAC中基于概念格的角色评估

基于角色的访问控制模型(RBAC)是一种常用的访问控制模型,但是由于现有的角色及其权限之间的关系由人工指定,导致成本较高且有可能存在权限分配不合理的情况,容易带来安全隐患.针对此问题,引入完备信息系统的信息粒度度量方法,结合访问控制的基本原则对需求中角色及权限信息的不确定性进行分析,作为系统需求的一种反馈与度量,为系统的信息使用提供帮助.最后,通过实验验证了该方法的有效性.     

Web信息系统中基于RBAC模型的访问控制模块设计与实现

介绍了各类访问控制技术,特别是基于角色的访问控制(role-based access control , RBAC)模型,同时根据Web信息系统的特点提供了一个基于RBAC模型的访问控制模块的实现. RBAC访问控制实现了用户与访问权限的逻辑分离,减少了授权管理的复杂性,降低了管理开销.     

基于角色的参数化访问控制模型

文章针对基于角色的访问控制（RBAC）模型在细粒度权限控制上存在的不足，对RBAC模型进行了扩展，提出了一种将权限划分为功能权限和数据权限的改进模型。该模型将数据权限从权限中独立并抽象出来，使功能权限和数据权限共同决定主体对客体的访问权限，从而实现细粒度的访问控制，改善了RBAC模型权限管理模式。同时，为提高角色授权效率，提出了一种参数化角色管理方法，增加了新建角色的默认指派，使得角色的授权过程由映射关系的逐个分配转变为对部分映射关系的修改和完善，降低了授权管理的复杂性，增强了权限分配的灵活性。     

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.     

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.     

Features of Women's language

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.     

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.     

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。     

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.     

A computer generator for randomly layered structures

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

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-