论局域网的安全防范

网络技术、通信技术和计算机技术的突飞猛进使得很多的企业单位、机关部门和学校搭建了属于自己的局域网.信息安全问题是局域网实际应用过程中最受关注的问题.本文阐述了局域网安全的内涵和意义,分析了目前局域网安全防范中存在的问题,并根据笔者的实际经验给出了有效增强局域网安全防范的相关建议.     

基于安全隔离的边界防护体系的设计与实现

本文针对电子政务信息系统的特点,设计了基于安全隔离的边界防护体系。将安全隔离技术应用到电子政务中,实现了数据的安全高效实时传输,形成了多方位的安全边界防护体系架构。     

Possible Energy Network with polygeneration system and CCS for China

On basis of adopting polygeneration systems for power and alternative fuels,capturing CO2 with near zero energy penalties,and storing CO2 on sites,a new kind of Energy Network can integrate energy utilization,CO2 capture,transportation and storage synthetically.Techno-economic analysis of this solution focusing on Inner Mongolia and the Yangtze River Delta districts had been carried with comparison to the chain method for energy utilization and CO2 sequestration.This solution can save 21.5% of energy,and re...     

基于TCN的地铁列车控制方案的研究

本文针对地铁车厢内控制设备分散的问题,设计了基于TCNRTP的地铁列车控制网络系统。采用NS2网络模拟软件构建的虚拟网络环境,编写消息数据传输层协议,通过测试列控网络的通信效率,得出了影响通信效率的因素;通过配置列控通信设备的基本功能和设定装置运行参数达到配置网络化通信的目的。     

BP神经网络训练算法的分析与比较

BP神经网络被广泛应用于模式识别、信号处理和自动控制等领域,其广泛性是由于它能实现任何连续映射,但由于BP网络训练所固有的复杂性,目前尚没有任何一种完全的算法能适用于任何BP网络的训练。本文介绍了MATLAB神经网络工具箱中各种训练算法的特点及其函数的参数形式,并对它们的收敛速度和内存消耗情况进行了比较,说明了其各自适用的网络。     

Visitor-artwork network analysis using object detection with image-retrieval technique

Recent museum exhibitions are becoming a means by which to satisfy visitor demands. In order to provide visitor-centric exhibitions, artwork must be analyzed based on the behavior of visitors, and not merely according to museum professionals' points of view. This study aims to analyze the relationship between museum visitors and artwork via a network analysis based on visitor behavior using object detection techniques. Cameras installed in a museum recorded visitors, and an object detector with a content-based image-retrieval technique tracked visitors from the videos. The durations spent with different artworks were measured, and the data was converted into a bipartite graph. The relationships between different artwork types were analyzed with a visitor-centered artwork network. Based on the visitors’ behavior, significant artworks were identified and the artwork network was compared to the arrangement of the museum. The tendency of edges in the artwork network was also examined considering visitors' preferences for artworks. The method used here makes it possible to collect quantitative data, with the results possibly used as a basis and for reference when analyzing artwork in a visitor-centered approach.     

Model checking response times in Networked Automation Systems using jitter bounds

Response time (RT) of Networked Automation Systems (NAS) is affected by timing imperfections induced due to the network, computing and hardware components. Guaranteeing RT in the presence of such timing imperfections is essential for building dependable NAS, and to avoid costly upgrades after deployment in industries.This investigation proposes a methodology and work-flow that combines modelling, simulation, verification, experiments, and software tools to verify the RT of the NAS during the design, rather than after deployment. The RT evaluation work-flow has three phases: model building, modelling and verification. During the model building phase component reaction times are specified and their timing performance is measured by combining experiments with simulation. During the modelling phase, component based mathematical models that capture the network architecture and inter-connection are proposed. Composition of the component models gives the NAS model required for studying the RT performance on system level. Finally, in the verification step, the NAS formal models are abstracted as UPPAAL timed automata with their timing interfaces. To model timing interfaces, the action patterns, and their timing wrapper are proposed. The formal model of high level of abstraction is used to verify the total response time of the NAS where the reactions to be verified are specified using a subset of timed computation tree logic (TCTL) in UPPAAL model checker. The proposed approach is illustrated on an industrial steam boiler deployment.     

汽车构造实验网络教学辅助系统设计

为切实提高汽车专业教学水平,建立全方位教学体系,设计基于网络的汽车构造实验教学辅助系统。系统充分利用学校现有计算机网络平台,利用多媒体和网络开发技术,开发或整合多媒体资料,开辟学习交流平台,依据课程学习规律和认知特点,建立起方便快捷、生动有趣的实验教学辅助系统。该系统基于现有教材,又高于教学内容,不仅对于传授汽车zai新技术和剖析专业难点,调动学习积极性,具有重要补充和推动作用,而且对于教学示范中心创建工作,也具有重要意义。     

多种类病毒相互作用下网络信道破坏程度估计

在多种类病毒的相互作用下,网络信道破坏程度呈现较强的非线性特点,不能准确约束病毒在相互作用下的破坏性.传统的网络破坏程度估计的过程中,仅仅以单一病毒破坏程度叠加的方式去计算参数,计算具有较强的主观性,没有准确描述不同病毒的破坏作用,对评估结果误差影响较大.为解决上述问题,提出一种基于粒子滤波算法的多种类病毒相互作用下网络信道破坏程度估计方法,利用欧式距离方法对全部病毒进行分类,获取不同类型病毒的网络信道破坏程度值.通过粒子滤波算法对单一个体约束的优势,将每一个不同类型的病毒看作一个粒子,并进行训练.根据训练结果,利用粒子滤波算法对当前时刻网络信道破坏程度进行估计,完成整体评估.实验结果表明,利用改进算法进行多种类病毒相互作用下网络信道破坏程度估计,能够有效提高估计的准确率.     

Performance comparison of reduced models for leak detection in water distribution networks

This paper presents a methodology for comparing the performance of model-reduction strategies to be used with a diagnostic methodology for leak detection in water distribution networks. The goal is to find reduction strategies that are suitable for error-domain model falsification, a model based data interpretation methodology. Twelve reduction strategies are derived from five strategy categories. Categories differ according to the manner in which nodes are selected for deletion. A node is selected for deletion according to: (1) the diameter of the pipes; (2) the number of pipes linked to a node; (3) the angle of the pipes in the case of two-pipe nodes; (4) the distribution of the water demand; and, (5) a pair-wise combination of some categories.The methodology is illustrated using part of a real network. Performance is evaluated first by judging the equivalency of the reduced network with the initial network (before the application of any reduction procedure) and secondly, by assessing the compatibility with the diagnostic methodology. The results show that for each reduction strategy the equivalency of networks is verified. Computational time can be reduced to less than 20% of the non-reduced network in the best case. Results of diagnostic performance show that the performance decreases when using reduced networks. The reduction strategy with the best diagnostic performance is that based on the angle of two-pipe nodes, with an angle threshold of 165°. In addition, the sensitivity of the performance of the reduced networks to variation in leak intensity is evaluated. Results show that the reduction strategies where the number of nodes is significantly reduced are the most sensitive.Finally this paper describes a Pareto analysis that is used to select the reduction strategy that is a good compromise between reduction of computational time and performance of the diagnosis. In this context, the extension strategy is the most attractive.