摘要:
根据用户所从事的具体工作划分用户群组的方法,归为同一用户群组的各个用户具有相同的角色集,同时由群组取代多名用户接受角色授权,这样多次用户角色授权就被压缩为一次群组角色授权,大大减少了授权工作量.文中设计了"群组图"用于形式化描述用户群组的性质,分析了在进行群组角色授权时应注意的问题,讨论了在RBAC模型中设置的用户群组与访问控制列表ACL(Access Control List)中的用户群组的本质区别.同时应用用户群组完成了中级人民法院办公自动化系统的用户角色授权.
摘要:
The goal of this paper is to research the topology discovery of a computer network algorithms. Sonic key techniques Of backbone topology discovery are discussed in detail, and sonic Solutions are proposed, Such as how to ascertain the link relations of network equipments, how to mark a router, how to avoid a router being accessed repeatedly, and how to distinguish a router from gateway. This paper also analyses the principle of subnet topology discovery and presents a method for discovering the live hosts in a subnet. On these basis, a backbone topology discovery algorithm and a subnet topology discovery algorithm are designed by ourselves. and the complexity of these algorithims are analysed. At last all the algorithms are implemented successfully in object oriented language-JAVA2.
作者机构:
Department of Computer Science, Central China Normal University, Wuhan, 430079, China;Department of Computer Science, Loughborough University, Loughborough, Leicestershire, LE11 3TU, United Kingdom
会议名称:
World Congress
关键词:
computer communication networks;computer simulation;control system analysis;linear control systems;stability analysis
摘要:
The present paper proposes a control-theoretic approach to design rate-based controllers in order to flow-regulate the best-effort traffic through high-speed computer communication networks. Classical control theory and Schur-Cohn stability test are exploited to design the traffic controllers for high-speed networks. The stability of closed-loop congestion controlled systems is analysed by utilizing Schur-Cohn stability criterion, which leads to certain necessary and sufficient stability condition under which the controlled network is asymptotically stable in terms of buffer occupancy. The proposed stability condition is then shown to be a key tool in designing a wide scope of adaptive controllers. Simulations are performed that show good performance of such controlled networks.
作者机构:
[Tan, LS; Yu, YJ; Liu, Q; Xiao, DB] Cent China Normal Univ, Dept Comp Sci, Wuhan 430079, Peoples R China.
通讯机构:
[Yu, YJ] C;Cent China Normal Univ, Dept Comp Sci, Wuhan 430079, Peoples R China.
关键词:
network management;control theory;SNMP;closed-loop control;real time
摘要:
Network management system (NMS) is required not only to have network performance monitoring function but also to have automated real time network control. Most NMSs configure devices manually without processing data from SNMP agents. In order to make it, automatic, it's suggested that automated NMS should be built based on SNMP and control theory. This proposed that Manager-Agent network management model is similar to the closed-loop control model. According to device features, local network control systems are divided into two kinds, one is switch control, and the other is server control. The engineering implementations of the two control systems are analyzed in detail. How to choose a sampling time in network control system is discussed because it's difficult in almost every network control system design. We find that sampling time should be close to the agent sampling time of devices in centralized control model, and it should be also larger than time delay of Internet in distributed network control model. To show how to realize network management with control theory,,an example about admission control system in a genetic algorithm computing server is illustrated step by step and control effects are tested. The experiments results support the novel approach is efficient to automated network management.
作者机构:
[Tan, LS; Yu, YJ; Liu, Q] Cent China Normal Univ, Dept Comp Sci, Wuhan 430079, Peoples R China.
通讯机构:
[Yu, YJ] C;Cent China Normal Univ, Dept Comp Sci, Wuhan 430079, Peoples R China.
关键词:
TSP;CORBA;Java;genetic algorithm;DGAandCORBA
摘要:
Distributed Genetic Algorithm (DGA) has been used to parallel computing and, Common Object Request Broker Architecture (CORBA) is, popular in software integration. In order to reduce the complexity of DGA software development and to minimize the maintenance costs, DGA software with CORBA and Java (DGAandCORBA) is proposed. The advantages and software architecture of DGAandCORBA are illustrated in detail. China Traveling Salesman Problem (CTSP) has been computed with different parameters and three rules about parameters selections are exposed. It's shown that the solution quality with best-migration policy is the same as that of random-migration policy, the good solution is easily available both in the case when migration rate is about 20parts per thousand. and reproduction generation is between 25,000, and 30,000. Finally, Several experiments are carried out to verify these rules. Experiments show the efficiency of our approach in solving TSP.