SOME TRAFFIC ISSUES IN THE DESIGN OF VIRTUAL PRIVATE NETWORKS OVER ATM

The emergence of broadband technologies such as ATM gives rise to new developments in the domain of virtual private networks (VPNs). In this paper, a target broadband VPN (B-VPN) service is proposed, which combines the cost savings of classic VPN services and the powerful features of private corporate networks (service integration, statistical multiplexing, etc.) enlarged by the use of ATM. To reach this B-VPN service, some architectural issues related to the network supporting the B-VPN service are discussed. The traffic implications of the possible architectural choices are then examined, and from this discussion some basic principles for a VPN architecture are drawn. Finally, target VPN architectures are proposed.     

Management of a pool of self-service cars

This paper deals with the problem of self-service cars arising in large companies where cars are at the employees' disposal to travel between different company sites. This problem also occurs in some big cities where electric cars are available for customers to make local journeys. The employee (or the customer) uses the car to travel from one site to another, and leaves it there so that other employees (or customers) can use it. This customer will use another car to travel to another site, if necessary. In this paper, we restrict ourselves to the case where the random variables which generate car requirements in a given site are independent identically distributed (i.i.d.) random variables, and we study the behaviour of the system according to a balancing strategy.     

USING A FUNCTIONAL LANGUAGE FOR PARSING AND SEMANTIC PROCESSING

This paper describes an original approach to semantics representation based on the use of a non-strict functional programming language with polymorphic typing. This approach provides a unified formalism needing no preprocessing or postprocessing to the functional language itself: parsing and semantics are declared naturally using function definition and evaluation is done by lambda application along the lines of Montague. We show that by changing only the model we can, after parsing, compute either the truth value of a sentence or its parse tree.     

峡江水电站大型灯泡贯流式水轮机技术

介绍了峡江水电站的水轮机参数、水力设计及模型试验和结构设计特点。在水力设计方面,采用最先进的CFD计算软件,对过流部件进行优化,特别是转轮叶片,改进叶片进口头部的脱流,提高大流量区的效率及低水头的出力,并通过模型试验进行了验证。为了保证机组整体结构安全性,进行了大量的计算,包括对重要部件进行有限元分析。转轮采用缸动式结构,转轮室叶片转角范围内采用整体不锈钢板模压,并对筋板进行加强。主轴密封采用了可靠的盘根径向密封。导水机构采用弹簧连杆结构,单作用接力器,在重锤重力作用下关机,保证机组的安全性。