A comparison of test statistics for the recovery of rapid growth‐based enumeration tests

This paper considers five test statistics for comparing the recovery of a rapid growth‐based enumeration test with respect to the compendial microbiological method using a specific nonserial dilution experiment. The finite sample distributions of these test statistics are unknown, because they are functions of correlated count data. A simulation study is conducted to investigate the type I and type II error rates. For a balanced experimental design, the likelihood ratio test and the main effects analysis of variance (ANOVA) test for microbiological methods demonstrated nominal values for the type I error rate and provided the highest power compared with a test on weighted averages and two other ANOVA tests. The likelihood ratio test is preferred because it can also be used for unbalanced designs. It is demonstrated that an increase in power can only be achieved by an increase in the spiked number of organisms used in the experiment. The power is surprisingly not affected by the number of dilutions or the number of test samples. A real case study is provided to illustrate the theory. Copyright © 2013 John Wiley & Sons, Ltd.     

基于solaris平台的DNS服务器侦测和阻止DOS攻击的实现

DNS服务器所面临的威胁集中表现出了互连网的脆弱性,针对DNS服务器的拒绝服务攻击是DNS服务器面临的最大威胁.提出了一种针对查询攻击进行侦测和阻止的思路,并且在solaris的平台上用perl语言来实现,能够保证DNS服务器有效地抵御常规攻击,为正常用户提供及时的服务.同时,本文也对伪造源IP的分布式拒绝服务攻击提出了一种解决方案.     

“It's the Beast Thing”

This article examines the representations of men and masculinities in contemporary crime narratives featuring a female protagonist. These “chick dick” stories (which adapt elements from the hardboiled detective novel, film noir, chick lit, and chick flicks) repeatedly engage with the gendered power dynamics made visible and problematic through the intersection of “chick” and crime genres, most particularly the sexualization of violence. In these narratives, popular masculinities operate as deployable concepts to dramatize contemporary gender relations. By tapping into the popular sentiment of a “crisis in masculinity,” chick dick texts also mobilize a rhetoric of unrepresentable male victimization and individual male pathologies. This strategy highlights the spaces and places in which masculinities are made vulnerable at the same time as it offers simplistic and individualized explanations for the systemic sexualized violence that dominate these narratives.     

Asymptotic behaviour of a test statistic for detection of change in mean of vectors

The paper gives an asymptotic distribution of a test statistic for detecting a change in a mean of random vectors with dependent components. The studied test statistic has a form of a maximum of a square Euclidean norms of vectors with components being standardized partial cumulative sums of deviations from means. The limit distribution was obtained using a result of Piterbarg [1994. High deviations for multidimensional stationary Gaussian processes with independent components. In: Zolotarev, V.M. (Ed.), Stability Problems for Stochastic Models, pp. 197–210].     

A single-featured EWMA-X control chart for detecting shifts in process mean and standard deviation

The combined EWMA-X chart is a commonly used tool for monitoring both large and small process shifts. However, this chart requires calculating and monitoring two statistics along with two sets of control limits. Thus, this study develops a single-featured EWMA-X (called SFEWMA-X) control chart which has the ability to simultaneously monitor both large and small process shifts using only one set of statistic and control limits. The proposed SFEWMA-X chart is further extended to monitoring the shifts in process standard deviation. A set of simulated data are used to demonstrate the proposed chart's superior performance in terms of average run length compared with that of the traditional charts. The experimental examples also show that the SFEWMA-X chart is neater and easier to visually interpret than the original EWMA-X chart.     

On Calculations Involving the Maximum Cell Frequency

We describe a method of computing the cumulative distribution function of the maximum and minimum cell frequencies in sampling distributions commonly encountered in the analysis of categorical data.The procedure is efficient for exact or approximate calculation in both homogeneous and non-homogeneous cases, is non-recursive, and does not require Dirichlet integrals.Some related statistical problems are also discussed.     

Evaluation of strategies to mitigate contagion spread using social network characteristics

Computer simulation is an effective tool for assessing mitigation strategies, with recent trends concentrating on agent-based techniques. These methods require high computational efforts in order to simulate enough scenarios for statistical significance. The population individuals and their contacts determined by agent-based simulations form a social network. For some network structures it is possible to gain high accuracy estimates of contagion spread based on the connection structure of the network, an idea that is utilized in this work. A representative social network constructed from the 2006 census of the Greater Toronto Area (Ontario, Canada) of 5 million individuals in 1.8 million households is used to demonstrate the efficacy of our approach. We examine the effects of six mitigation strategies with respect to their ability to contain disease spread as indicated by pre- and post-vaccination reproduction numbers, mean local clustering coefficients and degree distributions. One outcome of the analysis provides evidence supporting the design of mitigation strategies that aim to fragment the population into similarly sized components. While our analysis is framed in the context of pandemic disease spread, the approach is applicable to any contagion such as computer viruses, rumours, social trends, and so on.     

网络信息监控系统设计的研究

根据当前网络信息传播的混乱情况,在某种场合进行网络信息监控很有必要.该文提出了网络信息监控的几种实现方法和标准的信息监控流程,讨论设计网络信息监控系统的系统架构方法以及信息监控中应根据实际采用各种不同的技术组合,以达到全方位对网络信息进行监控.     

多波段光学探测系统的探测概率研究

针对光学联合探测子系统探测概率的不同特点,提出一种新的系统工作模式,使系统的最终探测概率有较大提高。当子系统的探测概率均比较低时,直接对子系统的探测数据进行融合,可以获得较高探测概率;当各子系统探测概率相差较大时,可先对探测数据进行选择,然后再进行数据融合,这样可以在总探测概率减小不大的情况下,使虚警概率明显降低。     

运用核Fisher鉴别分析和MPM分类器的入侵检测

为了提高分类器的正确率和减少训练时间,将特征提取技术与分类算法结合,提出了一种基于核Fisher鉴别分析和最小极大概率机算法的入侵检测算法。利用核Fisher鉴别分析技术提取关键特征,运用最小极大概率机对提取特征后的数据进行分类,采用离线数据集KDDCUP99进行实验。实验结果表明,该算法是可行和有效的,使分类性能和训练时间都得到了提高。