共查询到19条相似文献，搜索用时 343 毫秒
1.
TIAN Jie ZHANG Xin-fang WANG Tong-yang XIANG Wei Cheng Ming 《重庆大学学报(英文版)》2007,6(4):256-264
This paper introduces a solution to the secure requirement for digital rights management (DRM) by the way of geospacial access control named geospacial access control (GeoAC) in geospacial field. The issues of authorization for geospacial DRM are concentrated on. To geospacial DRM, one aspect is the declaration and enforcement of access rights, based on geographic aspects. To the approbation of digital geographic content, it is important to adopt online access to geodata through a spacial data infrastructure (SDI). This results in the interoperability requirements on three different levels: data model level, service level and access control level. The interaction between the data model and service level can be obtained by criterions of the open geospacial consortium (OGC), and the interaction of the access control level may be reached by declaring and enforcing access restrictions in GeoAC. Then an archetype enforcement based on GeoAC is elucidated. As one aspect of performing usage rights, the execution of access restrictions as an extension to a regular SDI is illuminated. 相似文献
2.
This paper provides an overview of models and methods for estimation of lifetime of technical components. Although the focus in this paper is on wind turbine applications, the major content of the paper is of general nature. Thus, most of the paper content is also valid for lifetime models applied to other technical systems. The models presented and discussed in this paper are classified in different types of model classes. The main classification used in this paper divides the models in the following classes： physical models, stochastic models, data-driven models and artificial intelligence, and combined models. The paper provides an overview of different models for the different classes. Furthermore, advantages and disadvantages of the models are discussed, and the estimation of model parameters is briefly described. Finally, a number of literature examples are given in this paper, providing an overview of applications of different models on wind turbines. 相似文献
3.
LONG Tao HONG Fan WU Chi SUN Ling-fi 《重庆大学学报(英文版)》2007,6(4):249-255
Access control in a grid environment is a challenging issue because the heterogeneous nature and independent administration of geographically dispersed resources in grid require access control to use fine-grained policies. We established a task-and-role-based access-control model for computational grid (CG-TRBAC model), integrating the concepts of role-based access control (RBAC) and task-based access control (TBAC). In this model, condition restrictions are defined and concepts specifically tailored to Workflow Management System are simplified or omitted so that role assignment and security administration fit computational grid better than traditional models; permissions are mutable with the task status and system variables, and can be dynamically controlled. The CG-TRBAC model is proved flexible and extendible. It can implement different control policies. It embodies the security principle of least privilege and executes active dynamic authorization. A task attribute can be extended to satisfy different requirements in a real grid system. 相似文献
4.
Jázef LUBZCZ 《浙江大学学报(A卷英文版)》2008,9(10):1309-1317
This paper presents an analytical saturation throughput model of IEEE 802.11DCF （distributed coordination function） with basic access in ad hoc mode. The model takes into account freezing of the backofftimer when a station senses busy channel. It is shown that taking into account this feature of DCF is important in modeling saturation throughput by yielding more accurate and realistic results than models known from literature. The proposed analytical model also takes into account the effect of transmission errors. All essential features of the proposed analytical approach are illustrated with numerical results. The presen- tation of the model is proceeded by an overview of approaches to IEEE 802.11 network performance evaluation presented in the literature. 相似文献
5.
ZHUHong FENGYu－cai 《上海大学学报(英文版)》2001,5(4):299-307
This paper propses a security policy model for mandatory access control in class B1 database management system whose level of labeling if tuple.the relation-hierarchical data model is extended to multilevel relation-hierarchical data model.Based on the multievel relation-hierarchical data model,the concept of upper-lower layer relational integrity is presented after we analyze and eliminate the covert channels caused by the database untegrity,Two SQL statements are extended to process polyinstantiation in the multilevel secure environment.The system is based on the multievel relation-hierarchical data model and is capable of integratively storing and manipulating multilevel complicated objects(e.g.,multilevel spatial data) and multievel conventional data(e.g.,integer,real number and character string). 相似文献
6.
Chu Chao-Hsien 《东南大学学报》2008,(Z1)
To address security and privacy issues in radio frequency identification (RFID) traceability networks, a multi-layer privacy and security framework is proposed, which includes four facets: a security model, a communication protocol, access permission and privacy preservation. According to the security requirements that are needed in an RFID system, a security model that incorporates security requirements that include privacy of tag data, privacy of ownership, and availability of tag identity is introduced. Using this model, a secure communication protocol that can be used for anti-counterfeiting, automatic identification and privacy preservation is then developed. In order to manage the number of parties, data records of items, and complicated transitions of access permissions in an item-level traceability context, a well-designed access control protocol is proposed to parties that can prove the physical possession of an item;meanwhile, to address the privacy issues during data sharing in an RFID network, a vision of database systems that take responsibility for the privacy of the data they manage is also presented. 相似文献
7.
Traditional studies on integrated statistical process control and engineering process control (SPC-EPC) are based on linear autoregressive integrated moving average (ARIMA) time series models to describe the dynamic noise of the system.However,linear models sometimes are unable to model complex nonlinear autocorrelation.To solve this problem,this paper presents an integrated SPC-EPC method based on smooth transition autoregressive (STAR) time series model,and builds a minimum mean squared error (MMSE) controller as well as an integrated SPC-EPC control system.The performance of this method for checking the trend and sustained shift is analyzed.The simulation results indicate that this integrated SPC-EPC control method based on STAR model is effective in controlling complex nonlinear systems. 相似文献
8.
Simulation and analysis of resin flow in injection machine screw 总被引：1，自引：0，他引：1
Ling-feng LI Samir MEKID 《浙江大学学报(A卷英文版)》2008,9(3):338-345
A method with simulation and analysis of the resin flow in a screw is presented to ease the control of some problems that may affect the efficiency and the quality of the product among existing screws in an injection machine. The physical model of a screw is established to represent the stress, the strain, the relationship between velocity and stress, and the temperature of the cells. In this paper, a working case is considered where the velocity and the temperature distributions at any section of the flow are obtained. The analysis of the computational results shows an ability to master various parameters depending on the specifications. 相似文献
9.
AbrahamJ.Yu 《高校文献信息学刊》1994,1(3):111-115
Authority control is critical for the quality of the bibliographic database. Authority control is important in guiding users from variant forms of headings to the controlled forms of headings and providing users with the related headings. With authority control, the forms of headings in the bibliographic records are consista,t and easy to access. Authority control not only increases the accuracy of searching but also makes retrieving records from the online bibliographic database easier. In the first part of the paper, the author brings out three formats for Chinese personal names in the online environment. Tire second part presents a new model for better authority control regarding Chinese presonal names. In the last part, the author emphasizes the importance of linking the online authority records with the bibliographic database. The quality of the database can be improved dramatically by providing vernacular access capability to the name authorty, records and ensuring that every personal name heading in the bibliographic records have corresponding Library of Congress name authority records。 相似文献
10.
Research on cubic polynomial acceleration and deceleration control model for high speed NC machining
Hong-bin LENG Yi-jie WU Xiao-hong PAN 《浙江大学学报(A卷英文版)》2008,9(3):358-365
To satisfy the need of high speed NC （numerical control） machining, an acceleration and deceleration （acc/dec） control model is proposed, and the speed curve is also constructed by the cubic polynomial. The proposed control model provides continuity of acceleration, which avoids the intense vibration in high speed NC machining. Based on the discrete characteristic of the data sampling interpolation, the acc/dec control discrete mathematical model is also set up and the discrete expression of the theoretical deceleration length is obtained furthermore. Aiming at the question of hardly predetermining the deceleration point in acc/dec control before interpolation, the adaptive acc/dec control algorithm is deduced from the expressions of the theoretical deceleration length. The experimental result proves that the acc/dec control model has the characteristic of easy implementation, stable movement and low impact. The model has been applied in multi-axes high speed micro fabrication machining successfully. 相似文献
11.
本文介绍了目前用户权限管理通常采用的几种方法。结合开放课程系统开发中的体验,以基于角色的访问控制（role-based access control,RBAC）模型为基础,提出并实现了一种扩展了的基于角色的访问控制方法。 相似文献
12.
结合传统的访问控制的优点,在充分考虑安全性的基础上,提出了一个关于WEB Service流程的授权架构模型,实现了电子商务平台更加安全、稳定、高效运行的目标。 相似文献
13.
Constraint is an important aspect of role-based access control and is sometimes argued to be the principal motivation for role-based access control (RBAC). But so far few authors have discussed consistency maintenance for constraint in RBAC model. Based on researches of constraints among roles and types of inconsistency among constraints, this paper introduces corresponding formal rules, rule-based reasoning and corresponding methods to detect, avoid and resolve these inconsistencies. Finally, the paper introduces briefly the application of consistency maintenance in ZD-PDM, an enterprise-oriented product data management (PDM) system. 相似文献
14.
基于属性的访问控制策略描述语言 总被引：3，自引：0，他引：3
首先提出了基于属性的访问控制策略,该方法利用用户和角色属性表达式来描述访问控制策略.然后,提出了扩展的XACML（扩展访问控制标记语言）策略描述语言A-XACML.A-XACML可以简单、灵活地表达各种应用环境中的访问控制策略,尤其是基于属性的访问控制策略.该语言及其框架通过数据类型、函数和逻辑组合来定义简单或复杂的访问控制策略.最后,给出了利用属性表达式和A-XACML来实现用户-角色指派的系统架构和应用实例.该实例表明属性表达式和A-XACML能够灵活简单地描述和实施复杂的访问控制策略. 相似文献
15.
黄玉芬 《辽宁科技学院学报》2021,23(1):1-3
近年来,随着分布式技术的大量使用,人们越来越关注分布式系统的安全性。跨域访问控制技术是解决分布式系统跨域访问的核心技术。文章将基于行为的访问控制模型应用于跨域访问控制,提出了基于行为的跨域访问控制模型,给出了跨域访问控制的行为映射规则,并通过一个应用场景说明了基于行为的跨域访问控制模型的具体实现过程。 相似文献
16.
梁泉 《福建工程学院学报》2009,7(4)
面向服务的网格体系结构是新一代网络的重要特征,而访问权限控制机制是面向服务网格模型中必须解决的问题.文章重点研究了服务网格的模型及对应的权限管理机制,提出一个提供服务质量保障的网格模型,支持QoS协商和资源虚拟化,在各层次间方便地提供QoS映射和监控.同时提出了一种访问权限的分配策略,基于角色模型在各实体间进行权限映射,简化了权限管理的过程.通过实际的过程模型分析,验证了服务网格模型及其权限分配策略的有效性和适应性. 相似文献
17.
18.
贾树生 《石家庄职业技术学院学报》2013,25(2):28-29
分析了权限管理的功能,基于角色访问控制模型设计了权限管理验证类PageBase,并以添加用户功能为例展现了PageBase类的验证作用,体现了角色访问控制模型的灵活应用和面向对象编程的设计优势． 相似文献
19.
基于角色访问控制模型实现 总被引：2，自引：0，他引：2
主要介绍在访问控制领域中基于角色访问控制模型的需求、发展和应用，并提出了基于角色访问控制模型数据库实现模型和API实现模型。基于角色访问控制模型通过角色继承实现角色结构化分层，反映现实组织的授权和责任，静态责任分离或者动态责任分离实现了责任分离，解决利益冲突，防止用于超越权限。这种模型实现了灵活的授权机制，便于分级管理，通过最小特权，减少网络实施风险，详细介绍并讨论基于角色控制的数据库模型和API模型的实现方法。 相似文献