MPLS VPN核心网的邻居保护方案

VPN(虚拟专用网)的安全性是用户首要关注的问题。分析了MPLS(多协议标签交换)VPN的安全保障机制和核心网可能遇到的安全威胁,在此基础上提出了安全改进方案并进行了实验验证。在核心网中,BGP(边界网关协议)邻居间采用MD5(信息摘要算法第五版)鉴权机制,LDP(标签分发协议)邻居间采用GTSM(通用TTL安全机制)。该方案同时考虑了安全性与处理复杂度问题,经验证可以很好地加强MPLS VPN核心网的安全性。     

Power levels and packet lengths in random multiple access with multiple-packet reception capability

This paper extends our earlier results. We assume that the receiver has the capability of capturing multiple packets so long as the signal-to-interference-plus-noise ratio (SINR) of each packet is above a designed threshold T throughout its transmission period. We prove that, compared with a multiple-power-level system, the single-power-level system in which all nodes transmit at the maximum allowable power level achieves optimal throughput, under a condition that T exceeds the value 3.33. Given a minimum throughput requirement, under the same condition on T, the single-power-level system also achieves the maximum average packet capture probability as well as the optimum energy usage efficiency. If the multiple-power-level systems are constrained such that higher power levels always have shorter packet lengths, then the above results hold for T greater than 2.     

A comprehensive multimodal eye recognition

Iris recognition is tested to be one of the most reliable approaches for automatic personal recognition under the infrared light. However, it is challenging and difficult to acquire good quality iris patterns of dark color eyes in the visible wavelengths. Sclera recognition can achieve good recognition accuracy in the visible spectrum, but the performance will drop when the sclera pattern is saturated. In this paper, we proposed a comprehensive multimodal eye recognition system that uses both iris and sclera patterns for recognition from the same eye image. The experimental results show that the proposed multimodal frontal eye recognition method can achieve better recognition accuracy than unimodal iris or sclera recognition. In addition, we propose a multimodal multi-angle eye recognition system that can further improve the recognition accuracy.     

用电子束曝光方法在优化设计的绝缘体上硅脊状波导上实现布拉格光栅的制作和评价

报道了一种用电子束曝光的方法在绝缘体上硅的脊状光波导上制做布拉格光栅的技术.考虑到实际的光子学集成的应用,讨论了这个带有布拉格光栅的脊状光波导的优化设计,给出了该布拉格光栅的测试和理论模拟结果.通过薄化绝缘体上硅的波导层的厚度和光栅的深腐蚀加工,获得了高达30cm-1的光栅耦合系数.     

干涉显微镜测量小球面曲率半径

研究了一种由单幅静态干涉图测量球面曲率半径的方法.针对小曲率半径(R＜50 mm)的球面,用林尼克干涉显微镜得到被测球面的静态干涉图.基于阻尼最小二乘法,拟合干涉条纹的光强曲线,得到被测小球面面形的多项式表达式,并由此计算出被测件的曲率半径.讨论了算法初值的选取方法,验证了算法精度并分析了误差因素.对比实验表明,本方法的与其他测试方法取得的结果相吻合.     

Simulation of interconnect inductive impact in the presence of process variations in 90 nm and beyond

The on-chip inductive impact on signal integrity has been a problem for designs in deep-submicrometer technologies. The inductive impact increases the clock skew, max timing, and noise of bus signals. In this letter, circuit simulations using silicon-validated macromodels show that there is a significant inductive impact on the signal max timing (/spl sim/ 10% pushout versus RC delay) and noise (/spl sim/2/spl times/RC noise). In nanometer technologies, process variations have become a concern. Results show that device and interconnect process variations add /spl sim/ 3% to the RLC max-timing impact. However, their impact on the RLC signal noise is not appreciable. Finally, inductive impact in 65- and 45-nm technologies is investigated, which indicates that the inductance impact will not diminish as technology scales.     

Diagnosis knowledge representation and inference

In this article, we presented three graphical modeling techniques for diagnostic knowledge representation and inference: behavioral Petri nets (BPNs), multisignal flow graphs, and Bayesian networks (BNs). By using the same example from (Portinale, 1997) we showed that both multisignal flow graph model and BN model yield the same diagnosis. In addition, we showed that the P-invariant concept in BPN is similar to the D-separation concept in BNs.     

基于FPGA的人工神经网络实现方法的研究

基于FPGA的神经网络实现方法已成为实际实时应用神经网络的一种途径.本文就十多年来基于FPGA的ANN实现作一个系统的总结,例举关键的技术问题,给出详细的数据分析.引用相关的最新研究成果,时不同的实现方法和思想进行讨论分析,并说明存在的问题以及改善方法,强调神经网络FPGA实现的发展方向和潜力及提出自己的想法.另外,还指出基于FPGA实现神经网络存在的瓶颈制约,最后对今后的研究趋势作出估计.     

基于ATP系统的非机动目标跟踪实验

考虑到无线光通信的捕获、瞄准和跟踪(ATP)系统对信标光斑实时、准确跟踪的需求,采用具有高频、大幅度补偿能力的音圈电机作为精跟踪执行部件,以此搭建了基于PC机控制的无线光通信演示实验系统。进行了不同速度下的非机动模拟跟踪实验,分别采集、分析并评价了粗跟踪和精跟踪的跟踪误差,并实时采集了通信光光功率。实验结果表明:ATP系统的跟踪误差标准差随着模拟目标运动速度的增加而增大,误差变化范围却无较为明显的规律,系统可长时间保持通信链路;此外,粗跟踪误差曲线中多次出现的误差尖峰可能与粗大值有关。     

基于锁相环技术的过程辨识方法研究

针对广泛应用的继电反馈自整定控制器辨识方法的局限性,提出一种基于锁相环原理的过程非参数模型辨识方法。以NI公司的虚拟仪器软件LabVIEW为开发平台设计了锁相环过程辨识系统,包括被控过程仿真器、PCI-6024E数据采集卡和锁相环辨识软件设计三部分。实践证明,该系统具有操作简单,辨识精度较高的特点,具有良好的应用前景。