ATM网上的LAN仍真

对作为计算机网络未来发展方向的ATM网如何仿真以太网和令牌环方案作了详细的描述。此方案的优势在于它允许现有的LAN应用在不作任何修改的情况下，便可在ATM网上运行。     

ATR Contributes More Than ATM in Intra-S-Phase Checkpoint Activation after IR,and DNA-PKcs Facilitates Recovery: Evidence for Modular Integration of ATM/ATR/DNA-PKcs Functions

The intra-S-phase checkpoint was among the first reported cell cycle checkpoints in mammalian cells. It transiently slows down the rate of DNA replication after DNA damage to facilitate repair and thus prevents genomic instability. The ionizing radiation (IR)-induced intra-S-phase checkpoint in mammalian cells is thought to be mainly dependent upon the kinase activity of ATM. Defects in the intra-S-phase checkpoint result in radio-resistant DNA synthesis (RDS), which promotes genomic instability. ATM belongs to the PI3K kinase family along with ATR and DNA-PKcs. ATR has been shown to be the key kinase for intra-S-phase checkpoint signaling in yeast and has also been implicated in this checkpoint in higher eukaryotes. Recently, contributions of DNA-PKcs to IR-induced G₂-checkpoint could also be established. Whether and how ATR and DNA-PKcs are involved in the IR-induced intra-S-phase checkpoint in mammalian cells is incompletely characterized. Here, we investigated the contributions of ATM, ATR, and DNA-PKcs to intra-S-phase checkpoint activation after exposure to IR of human and hamster cells. The results suggest that the activities of both ATM and ATR are essential for efficient intra-S-phase checkpoint activation. Indeed, in a wild-type genetic background, ATR inhibition generates stronger checkpoint defects than ATM inhibition. Similar to G2 checkpoint, DNA-PKcs contributes to the recovery from the intra-S-phase checkpoint. DNA-PKcs–deficient cells show persistent, mainly ATR-dependent intra-S-phase checkpoints. A correlation between the degree of DSB end resection and the strength of the intra-S-phase checkpoint is observed, which again compares well to the G2 checkpoint response. We conclude that the organization of the intra-S-phase checkpoint has a similar mechanistic organization to that of the G₂ checkpoint in cells irradiated in the G₂ phase.     

Domain–Specific High–Level Modeling and Synthesis for ATM Switch Prototyping

ATM switch, the core technology of an ATM networking system, is one of the major products in Fujitsu telecommunication business. However, current gate–level design methodology can no longer satisfy its stringent time–to–market requirement. It becomes necessary to exploit high–level methodology to specify and synthesize the design at an abstraction level higher than logic gates. This paper presents our prototyping experience on domain–specific high–level modeling and synthesis for Fujitsu ATM switch design. We propose a high–level design methodology using VHDL, where ATM switch architectural features are considered during behavior modeling, and a high–level synthesis compiler, MEBS, is prototyped to synthesize the behavior model down to a gate–level implementation. Since the specific ATM switch architecture is incorporated into both modeling and synthesis phases, a high–quality design is efficiently derived. The synthesis results shows that given the design constraints, the proposed high–level design methodology can produce a gate–level implementation by MEBS with about 15 percent area reduction in shorter design cycle when compared with manual design.     

ATM无源光网络中直流耦合突发模式光接收机分析

本文根据异步传输模式(ATM)无源光网络(APON)的实际要求,对直流耦合突发模式光接收机进行了理论分析,结果表明基于动态峰值检测的突发模式接收机其灵敏度代价和传输容量代价过高,而基于局部峰值检测的突发模式接收机则可较好满足APON的要求.     

利用MSTP技术组建市级公安专网

本文介绍广电采用MSTP技术组建市级公安专网的具体方案，分析组网过程中遇到的常见问题。     

Intelligent Video Traffic Smooth Mechanism for Multimedia Communication

A principal challenge in supporting real-time video services over ATM is the need to provide synchronous play-out in the face of stochastic end-to-end network delays. In this paper, an intelligent traffic smooth mechanism ( ITSM ) is proposed to meet the continuity requirement which is composed of a back-propagation neural network ( BPNN ) traffic predictor, a play-out buffer, and a fuzzy neural network ( FNN ) based play-out rate determinator. The BPNN traffic predictor online predicts the mean packet rate of the traffic in the future interval ( FI ) and the FNN is designed to adaptively determinate the play-out time according to the number of packets in the buffer and the traffic character predicted. Simulation results show that compared to the window mechanism, ITSM achieves high continuity with accepted delay. Furthermore, ITSM can be adaptively modified to meet the QoS of different kinds of services by FNN parameter training.     

解决IP服务质量的综合方案及其应用

为了使IP网能满足音频、视频等实时业务的要求．研究在IP网上对不同业务提供相应的服务质量(QoS)保障是很重要的。文中重点对资源预留协议(RSVP)、综合服务(IntServ)以及区分服务(DiffServ)等几种QoS方案进行分析和讨论，并提出两个合成方案，即IntServ与DiffServ结合以及IP融入ATM的模型，可以解决网络中的延迟问题，实现网络资源的共享，并阐述了如何在电力通信网中利用MPLS技术传送关键业务。     

OTN业务和现有SDH传输网的有效结合探讨

在现代发展过程中,在经济与科技高速发展的背景下,我国运营商在传输网上面的建设取得了突破性的发展,建设规模逐渐增大,同时网络质量也得到极大的提高,为了加强业务能力,满足大众的需求,还需要将网络朝扁平化方向发展,考虑以往传输网结构构成,结合实际需求,改变传输网内部结构,提升承载层的渗透能力,以下将对传输网进行讨论,并围绕OTN业务与SDH传输网有效整合进行论述。     

ASON在当前应用中存在的问题及分析

对ASON在当前应用中可能碰到的几个问题进行了分析，并提出了看法。     

SDH多路由组网的创新探索和研究

为解决传输SDH环路组网（即双路由组网）的机制限制,结合四川5·12地震后在多路由组网抗击灾难影响的实际应用,提出利用传统SDH设备进行多路由、多局向组网的方案。在充分利用现有传输资源、节省投资的前提下,提出SDH多路由的网络方案,达到类似＂ASON＂组网效果,增强网络的抗多点中断的能力,保证网络的安全、稳定运行。