Performance comparison of an 80-km-per-span EDFA system and a 160-km hut-skipped all-Raman system over standard single-mode fiber

In this paper, we present a comprehensive comparison of the performance of an 80-km-per-span erbium-doped fiber amplifier (EDFA) system and a hut-skipped (160-km-per-span) all-Raman system over standard single-mode fiber (SSMF) for the first time, using semianalytic models. The numerical results reveal that a hut-skipped all-Raman system (using one-order Raman pumping) can achieve comparable performance as the conventional 80-km-per-span EDFA system for a common 50-GHz-spaced 80 /spl times/ 10 Gb/s nonreturn-to-zero (NRZ) wavelength division multiplexing (WDM) system at typical fiber loss of 0.22 dB/km. For 100-GHz-spaced 40 /spl times/ 40 Gb/s carrier-suppressed return-to-zero (CS-RZ) WDM transmission, it was found that a hut-skipped all-Raman system can achieve even better performance than the current 80-km-per-span EDFA system. It was also found that the impact of pattern-dependent Raman crosstalk is more severe than interchannel cross-phase modulation (XPM) in a hut-skipped all-Raman system with 80 /spl times/ 10 Gb/s capacity.     

Channel Arrangement for optical communication subsystems with 12 parallel channels

This paper devoted to report the design and the achievement of an optical communication subsystem with 12 parallel channels in one chip. The system is capable of,transmitting 10 Gbps bidirectional date over hundreds of meters. It can provide error detection and correction by using 8B/10B encoding and Cyclical Redundancy Checking （CRC） encoding when only single-channel fails. The design scheme has already passed the simulation in FPGA. This technique is useful to enhance the capability and the reliability of the very short reach （VSR） transmission systems.     

A Macro Model of Frequently Changing Mobile Networks to Perform Flow and Access Control

The area covered by a mobile ad hoc network consists of obstacles that inhibit transmission and areas where communications can take place. Physical structures, such as buildings, that block transmission, or lakes, where forwarding nodes cannot be located, are permanent obstacles. Temporary obstacles are created as mobile nodes enter or leave an area. Our hypothesis is that the spaces between nearby obstacles are bottlenecks that inhibit the flows in the network. We partition the network into areas that are encompassed by obstacles and bottlenecks. All of the nodes in an area are treated as a single super node, and the bottlenecks between areas are the links between the super nodes. As individual nodes move, the flows and paths in the model change more slowly than the paths and flows between the individual nodes. We apply flow control algorithms to the model and perform admission control within a super node based on the flows that are assigned by the flow control algorithm. We apply the model to the Columbia University campus, and use max–min, fair bottleneck flow control to assign the flows. Our hypothesis is verified for this example.     

可穿戴设备归属权限转换协议研究

针对可穿戴环境下的信息安面临的巨大挑战,本文在考虑公共环境下可穿戴设备的用户转换的情景下,设计了一个适合可穿戴环境的用户权限转换协议框架,并对协议进行了详细设计.通过理论和实践分析得出,该协议可以满足可穿戴设备对安全性和实用性的要求,可以保障转换过程中的数据安全.     

基于多点通讯服务的视频点播系统

介绍了一种基于多点通讯服务（MCS）的视频点播系统（以下简称MVOD）的设计与实现技术。系统采用VOD服务器和点播用户集成在同一个功能单元的新方式,支持通道管理、视频数据管理、连接管理、点播服务、播放服务、用户接入管理等多种功能。该系统能够运行在Internet网上,具有强的管理能力和很好的扩展性能。     

DCT域网格编码量化及其在图像量化中的应用

本文提出了在离散余弦变换(DCT)域内作网格编码量化(TCQ)的新方法.该方法不仅利用了信号间的时间相关性,而且也利用了信号变换域内的相关性,该方法首先用一维或二维DCT变换减小变换域内的相关性,然后利用卷集编码和信号空间扩展来增大量化信号间的欧氏距离,并用维持比算法寻找最优量化序列.仿真结果表明,基于二维DCT的TCQ方法在相对大的灰度率下,比传统的TCQ方法好2dB左右,与此同时,TCQ又比最优标量量化好2dB左右.该方法还具有编码计算复杂度适中,解码简单以及对误差扩散不敏感的优点.     

A Narrowband Superconducting Filter Using Spirals With a Reversal in Winding Direction

A resonator consisting of a microstrip spiral, with a reversal in winding direction, is used for a narrowband superconducting filter. The fields are tightly confined, leading to the required small coupling coefficients, without a large separation between resonators. Nevertheless, tunability and power-handling capacity are better than some other resonators with localized fields. A quality factor exceeding a million was achieved. A 148 MHz, 0.1% bandwidth sixth-order quasi-elliptic filter is demonstrated     

《电路理论基础》第三版修订特色

《电路理论基础》教材第三版的修订工作正在进行。本文介绍了本次修订的策略,与第二版相比的主要变化,旨在与读者和同行教师进行广泛交流,进一步完善修订工作。     

Digital repetitive learning controller for three-phase CVCF PWMinverter

In this paper, a plug-in digital repetitive leaning control scheme is proposed for three-phase constant-voltage constant-frequency (CVCF) pulsewidth modulation inverters to achieve high-quality sinusoidal output voltages. In the proposed control scheme, the repetitive controller (RC) is plugged into the stable one-sampling-ahead-preview-controlled three-phase CVCF inverter system using only two voltage sensors. The RC is designed to eliminate periodic disturbance and/or track periodic reference signal with zero tracking error, The design theory of plug-in repetitive learning controller is described systematically and the stability analysis or overall system is discussed. The merits of the controlled systems include features of minimized total harmonic distortion, robustness to parameter uncertainties, fast response, and fewer sensors. Simulation and experimental results are provided to illustrate the effectiveness of the proposed scheme