改进计算机网络可靠性的方法探析

计算机网络的可靠性设计与建设问题的解决方法是当前相关领域的研究热点问题,其对于保证计算机网络安全稳定的运行有着重要的意义。     

IP城域网业务接入控制层业务备份技术探讨

越来越多的电信业务通过IP网络承载,对IP城域网的可靠性提出了极高的要求.业务接入控制层在IP城域网中是多业务融合承载的关键设备,在网络中承担着承上启下的功能.根据运营实践和业务测试,分析了业务接入控制层设备业务备份目前的技术现状,提出了在新型承载网络架构中构建高可靠性业务接入控制层的方法和建议.     

LFMCW雷达信号模糊函数分析

本文从ＬＦＭＣＷ雷达体制特点出发，导出了ＬＦＭＣＷ信号模糊函数，分析了它的特点以及它与ＬＦＭＣＷ雷达接收机中点目标回波信号的关系，阐明了它与脉冲雷达ＬＦＭ信号模糊函数的差别，并从模糊函数角度说明了运动目标回波的距离速度耦合及波形畸变现象。     

Recovery from control plane failures in GMPLS‐controlled optical networks

The health status of the control plane and the data plane of a GMPLS‐controlled optical network is independent in the physically separated control network implementation. In most control plane designs, besides the topology information, the entities of the routing protocol only record the number of available wavelengths on each link. However, the status of each wavelength is maintained by the entities of the signalling protocol. Without recovery ability of the signalling protocol CR‐LDP, a failure in the control plane will result in the permanent loss of the status information of wavelengths. A mechanism to recover the status information of the wavelengths is proposed. A downstream node maintains a label information database (LID) about assignable (free) labels in each incoming link. A copy of LID is redundantly stored in the upstream node as a label information mirror (LIM). A systematic procedure is proposed to synchronize the contents of a LIM and the corresponding LID. The initialization of a new LDP session with the enhanced recovery mechanism will guarantee the revival of the status information of wavelengths. It can recover multiple control channel failures, but it only applies to single node failure among any pair of adjacent nodes. © Crown copyright 2002. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.     

以可靠性为中心的维修技术工程应用探讨

以可靠性为中心的维修（RCM）是确定装备预防性维修需求的一种重要方法或手段,在装备维修保障领域得到广泛的重视和应用。在分析RCM技术发展现状和国内外的应用情况的基础上,针对RCM在工程实际应用中需要注意的一些问题进行了探讨。最后结合实例,说明如何应用计算机辅助分析软件（CARMES）,进行RCM分析。     

An improved SAR-GMTI method based on eigen-decomposition of the sample covariance matrix

An improved two-channel Synthetic Aperture Radar Ground Moving Target Indication (SAR-GMTI) method based on eigen-decomposition of the covariance matrix is investigated. Based on the joint Probability Density Function (PDF) of the Along-Track Interferometric (ATI) phase and the similarity between the two SAR complex images, a novel ellipse detector is presented and is applied to the indication of ground moving targets. We derive its statistics and analyze the performance of detection process in detail. Compared with the approach using the ATI phase, the ellipse detector has a better performance of detection in homogenous clutter. Numerical experiments on simulated data are presented to validate the improved performance of the ellipse detector with respect to the ATI phase approach. Finally, the detection capability of the proposed method is demonstrated by measured SAR data.     

1553B总线通讯的可靠性设计

为保证通讯的正常时序和避免空间环境[尤其是单粒子翻转效应（SEU）]对1553B总线通讯的危害性影响,建立了1553B总线通讯通用的失效模式分析模型。针对不满足通讯时序而引起的通讯失效,通过增加握手时序的方式加以避免。软件设计中针对典型的失效模式,如中断无法响应、帧格式错误等,给出与一般通讯软件不同的高可靠性软件设计流程,具体在设计方法上采取寄存器定时更新、存储区表决法以及冗余设计等可靠性措施避免失效,并通过对固定位置的存储单元模拟SEU故障注入的方式进行验证,降低了单粒子翻转的危害性,提高了1553B总线通讯的可靠性,具有普遍意义。     

On the limitations of transimpedance amplifiers as tools for low-frequency noise characterization

An experimental set-up for the characterization of low-frequency noise on two terminal devices is reported. The experimental set-up is based on the use of the commercial transimpedance amplifier (TA) EG&G5182. This paper addresses the influence of the TA on the noise characterization process by describing the TA as a non-ideal operational amplifier with a feedback resistor. The impact of the TA finite input resistance and voltage gain is highlighted through comparison with measurements carried out on resistors and diodes.     

Three-step concept (TSC) in modeling microelectronics reliability (MR): Boltzmann–Arrhenius–Zhurkov (BAZ) probabilistic physics-of-failure equation sandwiched between two statistical models

When encountering a particular reliability problem at the design, fabrication, testing, or an operation stage of a product’s life, and considering the use of predictive modeling to assess the seriousness and the likely consequences of the a detected failure, one has to choose whether a statistical, or a physics-of-failure-based, or a suitable combination of these two major modeling tools should be employed to address the problem of interest and to decide on how to proceed. A three-step concept (TSC) is suggested as a possible way to go in such a situation. The classical statistical Bayes’ formula can be used at the first step in this concept as a technical diagnostics tool. Its objective is to identify, on the probabilistic basis, the faulty (malfunctioning) device(s) from the obtained signals (“symptoms of faults”). The recently suggested physics-of-failure-based Boltzmann–Arrhenius–Zhurkov’s (BAZ) model and particularly the multi-parametric BAZ model can be employed at the second step to assess the remaining useful life (RUL) of the faulty device(s). If the RUL is still long enough, no action might be needed; if it is not, corrective restoration action becomes necessary. In any event, after the first two steps are carried out, the device is put back into operation (testing), provided that the assessed probability of its continuing failure-free operation is found to be satisfactory. If the operational failure nonetheless occurs, the third, technical diagnostics step should be undertaken to update reliability. Statistical beta-distribution, in which the probability of failure is treated as a random variable, is suggested to be used at this step. While various statistical methods and approaches, including Bayes’ formula and beta-distribution, are well known and widely used in numerous applications for many decades, the BAZ model was introduced in the microelectronics reliability (MR) area only several years ago. Its attributes are addressed and discussed therefore in some detail. The suggested concept is illustrated by a numerical example geared to the use of the prognostics-and-health-monitoring (PHM) effort in actual operation, such as, e.g., en-route flight mission.     

基于统计的灰度视频自适应背景建模算法

针对灰度视频的目标检测依赖先验知识、召回率低以及单一算法无法同时兼顾静态与动态背景等问题,提出一种基于统计的背景建模算法。该算法无需先验知识,根据统计信息可以准确区分静态背景和动态背景,并采取不同的检测策略提取目标。对于静态背景,采用改进的三帧差分法自适应设置阈值,可以保证较高的召回率。对于动态背景,采用改进的概率密度估计法可以有效降低虚警率。采用所提算法对光照变化以及阴影进行处理,可以进一步提升算法的性能。在公开数据集与实际采集红外数据进行验证实验。实验结果表明,所提算法在多种场景中处理灰度视频的结果比其他传统算法好,在保证准确率的同时可以极大地提升召回率,并且有效提高目标的完整性。