入侵检测系统在水务网络安全管理中的应用与研究

本文介绍了水务信息化快速发展进程中,水务网络安全管理工作的重要性,水务网络安全管理现状,分析了当前水务网络面临的安全风险,引入入侵检测系统,在分析其面临的安全挑战的基础上,研究了入侵检测系统在水务网络中的部署原则、应用架构和安全管理措施。     

PHP webshell实时动态检测

PHP Webshell是一种使用PHP编写的可以在web服务器中执行的网站后门文件。现有网站采用的基于特征匹配检测和网络流量分析的webshell检测方法难以检测经过变形或加密的webshell。本文提出了一种基于PHP扩展的webshell实时动态检测方法,该方法基于PHP扩展对PHP代码的编译执行进行监控并结合外部输入变量的标记追踪、黑白名单机制来进行webshell的实时动态检测。     

云计算数据服务主动安全防御系统探讨

随着云计算数据服务的快速发展和应用,大大地改变了人们的工作、学习和生活模式。云计算数据服务带来极大便利的同时,也给人们带来了潜在的威胁,因此需要构建网络安全主动防御系统,提高网络安全性能。文章详细地分析了云计算数据服务面临的安全威胁,阐述了云计算服务平台主动安全防御系统及采用的技术,提高了云计算数据服务平台的安全性能。     

Bromate Ion Analysis By Ion Chromatography

Bromate ion occurs during ozonation of bromide-containing waters. The current WHO guideline for bromate ion is 25 μg/L. Bromate analysis in drinking waters can be performed by various techniques. However, given the commonly low concentrations of bromate ion found in drinking waters, the classical methods do not fit for bromate analysis in most cases.

A specific conductimetric method with anion suppression which enhances analyte detection by lowering the eluent conductivity is described in this paper for low bromate level analysis. Three eluents have been tested in order to have the best signal to noise ratio. Some other parameters likely to interfere in bromate ion detection (nitrate and sulfate in particular) are also investigated. Taking into account the results of three interlaboratory trials between six European laboratories, a 2 μg/L detection level for bromate can be established.     

Application of real-time quantitative PCR for the detection of selected bacterial pathogens during municipal wastewater treatment

Bacteria were detected at five stages of municipal wastewater treatment using TaqMan(R) real-time quantitative PCR (qPCR). Thirteen probe and primer sets were tested for diverse pathogens that may be present in wastewater, including Aeromonas hydrophila, Bacillus cereus, Clostridium perfringens, Enterococcus faecalis, Escherichia coli, E. coli O157:H7, Helicobacter pylori, Klebsiella pneumoniae, Legionella pneumophila, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella sp., and Staphylococcus aureus. The sensitivity of the assay was 100 fg of genomic DNA (=22 gene copies), based on a standard curve generated using A. hydrophila purified DNA. Samples from five stages of wastewater treatment were collected, including raw wastewater, primary effluents, mixed liquor, waste activated sludge and final effluents. In duplicate samples, E. coli, K. pneumoniae, C. perfringens and E. faecalis were detected throughout the wastewater process, and their numbers decreased by 3.52-3.98, 4.23-4.33, 3.15-3.39, and 3.24 orders of magnitude respectively, between the raw wastewater and final effluent stage. This qPCR method was effective for the detection of pathogens in wastewater and confirmed that the risk of exposure to pathogens in the wastewater discharge was well within the Environment Canada guidelines.     

下线检测系统在变速器早期故障诊断中的应用

介绍了Reilhofer系统在汽车变速器台架检测中的应用,通过对变速器典型故障案例的振动信号分析,快速地找到故障来源,解决了变速器箱基本的噪声问题,确保了变速器的质量。     

下线检测系统在变速器早期故障诊断中的应用

介绍了Reilhofer系统在汽车变速器台架检测中的应用,通过对变速器典型故障案例的振动信号分析,快速地找到故障来源,解决了变速器箱基本的噪声问题,确保了变速器的质量。     

基于图像线灰度和BP神经网络的织物疵点检测

探讨织物疵点自动检测的方法。通过对4种常见织物疵点的图像进行线灰度曲线分析和处理,提取疵点图像的特征值,送入BP神经网络进行识别,从而实现织物疵点的检测。试验结果表明,该方法取得了较好的检测效果,织物疵点识别率达到93%以上。认为,此法能够有效识别出织物中的几类常见疵点,应进一步研究,以提高其识别准确率。     

大型油压机柱塞缸工艺设计

柱塞缸是大型油压机的主要载荷部件和执行元件,外形尺寸大,精度要求高.传统的工艺方法为毛坯实芯整体锻造,然后挖空再加工,综合费用高.本文介绍了一种新型的工艺设计方案,采用分体结构并利用窄间隙埋弧自动焊方式,彻底改变了常规加工方式带来的不足.     

A contaminant detection system for early warning in water distribution networks

Water distribution systems are spatially diverse. As such, they are inherently vulnerable to accidental or deliberate physical, chemical, or biological threats. Efficient water quality monitoring is one of the most important tools to guarantee a reliable potable water supply. A methodology and two example applications for finding the optimal layout of a detection system, taking explicitly into account the dilution and decay properties of the water quality constituents as distributed with flow, as well as the ability of the monitoring equipment to detect contaminant concentrations, are formulated and demonstrated. The detection system outcome is aimed at capturing contaminant entries within a pre-specified level of service (LOS) defined as the maximum volume of polluted water exposure to the public at a concentration higher than a minimum hazard level. The proposed methodology couples hydraulic simulations with graph theory techniques to identify a minimum set of monitoring stations that ‘covers’ the entire network for a given LOS, at a maximum degree of system invulnerability. The model developed extends a previous work of the authors through explicitly considering the deterioration and dilution of water quality as distributed with flow, and by taking into account the monitoring equipment capabilities to detect pollutant concentrations. The methodology is demonstrated using two example applications.