基于生成树算法的链路层拓扑发现研究

随着大规模交换网络的发展,网络拓扑发现的研究由网络层拓展到数据链路层。链路层的拓扑发现能够发现网络层拓扑发现无法发现的局域网内部的详细的物理连接情况,对网络配置管理具有重要意义。研究了目前基于地址转发表（AFT）的方法,针对现有算法的不足作了一定分析,提出了一种基于生成树算法（STA）的链路层网络拓扑发现算法,利用SNMP获得网桥MIB中的生成树信息,通过分析这些信息计算出链路层的网络拓扑。该算法相比其它算法更简单、高效,有应用价值。     

论用Linux/PC构建电力系统SCADA通用平台

为向我国 2 2 0kV及以上电压等级的SCADA系统提供可靠性高、普遍实用、具有自主知识产权且性能价格比高的系统软硬件平台 ,结合计算机技术发展的最新成果 ,论述了基于Intel架构的PC服务器与Linux操作系统用于构建SCADA平台的必要性和可行性 ,同时提出了平台的构建方案。从电力系统中广泛存在的监控后台需求出发 ,讨论了现有Solaris/Sparc、MSWindows/Intel等多种方案的局限性 ,并针对PC的局限 ,着重论述了各项关键指标的解决办法。得出的结论是 ,采用该Linux操作系统     

A combined M5P tree and hazard-based duration model for predicting urban freeway traffic accident durations

The duration of freeway traffic accidents duration is an important factor, which affects traffic congestion, environmental pollution, and secondary accidents. Among previous studies, the M5P algorithm has been shown to be an effective tool for predicting incident duration. M5P builds a tree-based model, like the traditional classification and regression tree (CART) method, but with multiple linear regression models as its leaves. The problem with M5P for accident duration prediction, however, is that whereas linear regression assumes that the conditional distribution of accident durations is normally distributed, the distribution for a “time-to-an-event” is almost certainly nonsymmetrical. A hazard-based duration model (HBDM) is a better choice for this kind of a “time-to-event” modeling scenario, and given this, HBDMs have been previously applied to analyze and predict traffic accidents duration. Previous research, however, has not yet applied HBDMs for accident duration prediction, in association with clustering or classification of the dataset to minimize data heterogeneity. The current paper proposes a novel approach for accident duration prediction, which improves on the original M5P tree algorithm through the construction of a M5P-HBDM model, in which the leaves of the M5P tree model are HBDMs instead of linear regression models. Such a model offers the advantage of minimizing data heterogeneity through dataset classification, and avoids the need for the incorrect assumption of normality for traffic accident durations. The proposed model was then tested on two freeway accident datasets. For each dataset, the first 500 records were used to train the following three models: (1) an M5P tree; (2) a HBDM; and (3) the proposed M5P-HBDM, and the remainder of data were used for testing. The results show that the proposed M5P-HBDM managed to identify more significant and meaningful variables than either M5P or HBDMs. Moreover, the M5P-HBDM had the lowest overall mean absolute percentage error (MAPE).     

基于算术傅里叶变换的小波变换快速算法

利用算术傅里叶变换(AFT)计算离散傅里叶变换(DFT)可使其乘法计算量仅为D(N）。文章根据这一特点，结合Mallat算法原理及离散傅里叶算法结构特征，提出了一种离散小波变换的快速算法，给出了数学推导过程，并对实验结果进行了分析。     

干红辣椒中黄曲霉毒素B1的判定

在遵循实验测定原理，不影响测定结果的前提下，对样品的前处理，提取的过程、测定的方式进行适当的改变和调整，并利用黄曲霉毒素B1的特性进行确证，从而对干红辣椒中的黄曲霉毒素B1进行定性，定量分析，效果明显，结果满意。     

边界面法数值结果的云图表征

边界面法继承了传统边界元法的优点,并将几何实体的边界曲面离散为参数空间里的曲面单元,在处理一些特殊问题如移动边界、高梯度、大变形等方面显示出特殊的优越性。但是也使得计算结果的后处理遇到困难。提出了一种基于黎曼度量推进波前法生成三角背景网格的实用边界面法计算结果后处理方法。该法对求解域剖分成三角背景网格然后将计算结果映射到网格节点上,通过区域填充获得计算结果的云图。温度场的数值算例表明该方法可靠实用。     

一种具有普适性的单子网物理拓扑发现算法

文中提出了一种适用于单子网异构IP网络的物理拓扑发现算法,此算法基于网络中的SNMP MIB库,具有普适性.在AFT信息不足的情况下,可用端口流量的关系获得端口的连接信息.理论和仿真证明,即使在有个别网络元素不支持SNMP的情况下,此算法仍可准确地进行物理拓扑发现.     

Improving the Product Reliability in Multistage Manufacturing and Service Operations

Monitoring and improving the product reliability is of main concern in a large number of multistage manufacturing processes. The process output is commonly inspected under limited load conditions, and the tensile strength of reliability‐related quality characteristic is measured. This brings about censored observations that make the direct application of traditional control charts futile. The monitoring procedure becomes aggravated when the influence of variable competing risk is pronounced during the conducted test. To deal with this critical issue, we propose a regression‐adjusted cumulative sum (CUSUM) chart to effectively monitor a quality characteristic that may be right censored because of both fixed and variable competing risks. Moreover, two exponentially weighted moving average (EWMA) control charts on the basis of conditional expected values are devised to detect decreases in the tensile mean. The comparison of the three competing monitoring schemes confirms the superiority of the regression‐adjusted CUSUM procedure. Not only is the proposed control chart applicable to manufacturing processes with the aim of monitoring reliability‐related quality variables, it is also appropriate for monitoring similar quality measurements in service operations such as survivability measures in healthcare services. Copyright © 2011 John Wiley & Sons, Ltd.     

Dietary intake of aflatoxins in the adult Malaysian population – an assessment of risk

Exposure to aflatoxins in the adult Malaysian diet was estimated by analysing aflatoxins in 236 food composites prepared as “ready for consumption”. Dietary exposure to aflatoxin B1 (AFB1) ranged from 24.3 to 34.00?ng/kg?b.w./day (lower to upper bound), with peanuts being the main contributor. Estimated liver cancer risk from this exposure was 0.61–0.85 cancers/100,000 population/year, contributing 12.4%–17.3% of the liver cancer cases. Excluding AFB1 occurrence data higher than 15?µg/kg reduced exposure by 65%–91% to 2.27–11.99?ng/kg?b.w./day, reducing the cancer risk to 0.06–0.30 cancers/100,000 population/year (contributing 1.2%–6.1% liver cancer cases). Reducing further the ML of AFB1 from 15 to 5?µg/kg yielded 3%–7% greater drop in the exposure to 0.47–10.26?ng/kg?b.w./day with an estimated risk of 0.01–0.26 cancers/100,000 population/year (0.2%–5.1% liver cancer cases attributed to dietary AFB1). These findings indicate that current MLs are adequate in protecting Malaysians’ health.     

任意分辨率的SSCA算法研究

提出当DFT点数不是2的整数次幂时,用AFT计算SSCA算法中的DFT得到信号循环谱,并对AFT中的乘法进行改进.借助实数乘法和实数加法运算量的换算系数,用加法次数作为衡量算法计算量的标准,给出改进的AFT和DFT、FFT的计算量的闭合表达式,并用它们分析SSCA算法的计算量.最后,利用AFT对SSCA算法进行实现和性能仿真.仿真和试验结果表明:根据不同的分辨率,采用FFT或AFT计算SSCA算法中的DFT,能以最小的运算量实现任意分辨率的SSCA算法.