流量矩阵估算的研究

流量矩阵是许多网络规划和流量工程任务的关键输入,精确的流量矩阵至关重要,但直接监控非常具有挑战性.因此,如何根据对有限链路的测量数据和路由信息等先验信息,通过合理建模来推断流量矩阵,成为重要的研究课题.首先给出了流量矩阵的基本概念和估算原理;然后对近年来提出的20多种不同的解决流量矩阵估算问题的方法进行分类剖析,总结了目前流量矩阵估算方法的最新研究进展,并讨论了部分方法的性能和估算误差;最后讨论了未来流量矩阵估算的研究趋势和应用前景.     

基于Wiener模型的某型导弹电连接器寿命预测

某型导弹电连接器属于高可靠性、长寿命产品,为了预测其寿命提出了基于Wiener模型的性能退化量分析方法。以电连接器的接触电阻作为性能参量,通过温度、湿度双应力加速退化试验获取了其性能退化数据。利用Wiener模型对样品退化轨迹进行拟合,使用广义艾林模型描述了样品寿命与温度、湿度之间的关系。使用极大似然估计的方法,对所有性能退化数据进行整体统计推断,估计出了模型参数,对电连接器进行了寿命预测。     

Nitrogen removal assessment through nitrification rates and media biofilm accumulation in an IFAS process demonstration study

An IFAS demonstration study was conducted at the 76,000 m³/day (20MGD) James River Wastewater Treatment Plant (JRTP) located in Newport News, Virginia by converting one fully-aerobic conventional aeration basin with dedicated secondary clarification to a 7041 m³/day (8404 m³/day max month) IFAS train in a modified Ludzack-Ettinger (MLE) configuration. During the study, biomass concentrations on the biofilm carriers were monitored (weekly) as well as nitrogen species concentrations in the IFAS reactor to quantify the nitrogen transformations occurring within the demonstration tank. In a related effort, nitrification kinetics for ammonia and nitrite oxidizing bacteria were monitored on a weekly basis for IFAS media alone, IFAS process mixed liquor without media, and IFAS mixed liquor and media together in an effort to identify the location of nitrification activity (i.e. on the media or in the suspended culture) in the IFAS process. Biomass quantity on the media was generally observed to be inversely related to temperature except during a period when an auxiliary carbon source contaminated with fungi was introduced. Both ammonia oxidizing and nitrite oxidizing bacterial activity were elevated on the carriers compared to the suspended culture (AOB_media: 4.97 mgNOx/gMLSS/hr; AOB_suspended: 1.72 mgNOx/gMLSS/hr; NOB_media: 7.55 mgNOx/gMLSS/hr; NOB_suspended: 0.82 mgNOx/gMLSS/hr) during all periods of the study. In-basin nitrification rates calculated based on nitrogen profiling efforts averaged 0.90 mgNOx/m²/day which was in good agreement with the average of 0.89 mgNOx/m²/day for IFAS mixed liquor and media from batch testing.     

对数正态分布下基于MLE的红外LED的寿命预测

为了获得红外LED的寿命信息,采用对数正态分布函数描述了红外LED的寿命分布,利用极大似然法(MLE)估计了对数均值和对数标准差,完成了恒定及步进应力实验数据的统计和分析,并自行开发了寿命预测软件。数值结果表明,红外LED的寿命服从对数正态分布,其加速模型符合逆幂定律。精确计算的加速参数使得快速估算红外LED寿命成为可能。     

基于多变量最大Lyapunov指数高边坡 稳定分区研究

 最大Lyapunov指数(MLE)能够揭示边坡变形系统演化的非线性混沌特征,且理论与实践证明多变量较单变量时序计算得到的MLE更为真实。探讨多变量相空间重构理论,基于相点演化的时间轨道不可逆与可逆特性提出三维变形时序MLE双向搜索修正方法。采用小湾水电站左岸2#山梁高边坡三维变形监测数据进行MLE计算,以MLE为稳定判据并结合边坡变形失稳率与失稳度进行分区研究,得出2#山梁高边坡由下至上牵引式变形特征。研究表明,新方法有效可靠,且能够为高边坡稳定性分区评价与治理提供依据。