2019年翻译资格笔译初级考试模拟试题：虚拟网络

　　虚拟网络是一种依赖互联网基础设施所提供的传输能力，但又具有独立拓扑结构和信息传递规则的应用层网络行为逻辑网络。人们利用新型耦合抽象模型考察典型的虚拟网络逻辑拓扑给互联网整体特性带来的影响。结构表明在虚拟网络作用下，节点数据包排队长度存在相变特性，相变临界点比对规则网络发生了明显左移，网络性能相对恶化。当数据包注入速率小于相变临界速率时，节点数据包排队长度不相关或短程相关;在接近临界速率处，节点数据包排队长度长程相关，幂指数H增大，网络获得更强的长程相关性。同时，在注入速率大于或等于临界速率时，虚拟网络行为使网络呈现出一致的长程相关特性。

　　参考译文

　　A virtual network is defined as a logical network, in which users exhibit their access behaviors. Virtual networks rely on physical computer networks like the Internet, but here different topologies, and cause significant influence on the physical networks. A novel two-tier model is used to study influences of virtual networks to Internet collective behavior. It is shown that the queue lengths of the node data packets present phase transition characteristics. Moreover, the phase transition critical point moves to the left and network performance is deteriorated. In a free flow, the nodes are independent of each other or short-range correlative. In the critical state, the nodes are long-range correlative, and there exists a higher power exponent H which means stronger long-range correlation. When the system state is on the right of critical point, virtual network behaviors make the network to present consistent long-range correlative characteristic.