共查询到20条相似文献,搜索用时 46 毫秒
1.
2.
目的提出一种基于画面分析的机械故障诊断方法,用于印刷机械中印刷单元的故障模式分类。方法通过印刷特定图像,获取印刷单元在正常与故障状态下的印刷画面,从网点覆盖率、灰度特征和画面纹理特征等3个方面构建表征印刷单元状态的多元图像特征集,并通过SVM构建故障识别网络。结果利用多元统计方法分析了印刷单元6类故障与特征集的映射关系,依靠画面特征实现了故障类别判断;经过实际故障诊断试验验证,所提出方法的准确率可达90%以上。结论图像特征集对于印刷机故障有着很好的分类表征能力,为印刷机维护提供了新的理论和方法。 相似文献
3.
4.
目的为了更直观、有效地评估游戏产品的用户体验(User Experience,UX),消除单一评估标准的不确定性。方法从传统的MDA游戏设计的角度出发,引入用户的生理特征测量,构建基于动态贝叶斯网络(Dynamic Bayesian Network,DBN)的用户体验评估模型。该模型通过MDAUX框架提取用户体验影响因子,作为贝叶斯网络的输入层节点,通过生理特征测量方法提取用户的脑电和眼动状态,作为贝叶斯网络输出层节点,以一阶隐马尔可夫模型(Hidden Markov Model,HMM)表示两个相邻时间片上用户体验元素的影响关系,从而动态地展示用户体验状态。结果通过生理特征测量实验验证该模型的可行性,通过建立知识平台实践了模型的应用。结论结合生理特征测量的用户体验评估模型可有效反映用户体验状态。 相似文献
5.
近几年来,随着因特网的飞速发展,网络安全问题日益突出,在这种情况下,网络管理与安全审计系统孕育而生,其审计重点主要在网络的访问行为和网络中的各种数据。对防火墙日志分析方面进行一系列研究,并利用SQL Server数据库设计基于日志分析的网络管理与安全审计系统,系统的实验结果说明日志分析技术的实用价值。目前,该系统已经应用于某广电网络。 相似文献
6.
对于供输弹系统早期故障中信号成分复杂,故障征兆难以识别的问题,提出了基于同步压缩变换(SST)时频图纹理特征的故障诊断方法。使用EEMD方法对供输弹系统振动信号进行预处理,对分解的分量进行相关系数运算,选取与原始信号相关系数大的前4层分量对信号进行重构,达到了一定的降噪效果;接着利用供输弹系统不同状态的信号通过同步压缩变换时频分析,得到反映不同运行状态的二维时频图像,并进行灰度化处理;利用灰度共生矩阵法与灰度梯度共生矩阵,对其进行纹理特征的提取,为与传统方法做对比,提取了信号经EEMD分解后,与原始信号相关系数大的前4层分量的能量百分比作为特征;使用基于核的模糊C均值聚类,对供输弹系统三种不同状态振动信号的图像纹理特征和能量百分比特征进行分类识别,并与模糊C均值聚类进行对比。实验结果表明,该方法能有效地对自动供输弹系统早期故障进行识别,且识别正确率达91.21%。 相似文献
7.
为了提高网络的整体安全性,提出了基于攻击图的网络安全策略制定方法.该方法首先从分布并行处理角度将不同区域的目标网络进行脆弱性分析任务划分,采用分布并行处理技术进行攻击图构建;其次,利用生成的全局攻击图识别目标网络中存在的脆弱性之间的关系,以及由此产生的潜在威胁;最后,将攻击图与遗传算法相结合,建立相应的数学模型,把安全策略的制定问题转化为带有惩罚的非约束优化问题,以最小的成本保证目标网络的安全.实验结果表明,该方法具有较高的攻击图生成效率,并且降低了攻击图生成时的系统资源消耗.该方法可以帮助网络安全管理人员有针对性地进行安全防护,能够适用于评估大规模复杂网络系统的整体安全性. 相似文献
8.
9.
防火墙技术在网络安全上的应用 总被引:2,自引:0,他引:2
在分析如今网络的形势基础上简要分析防火墙技术在网络安全上的应用,并重点介绍分析状态检测技术的利用.在最后给出网络安全的一个宏观把握方式以及发展趋势并给出综合性意见。 相似文献
10.
高压断路器操动机构振动信号为非平稳性信号,蕴含着丰富的操动机构工作状态的信息,对操动机构工作状态的检验辨识具有重大意义。提出一种基于小波时频图和卷积神经网络的断路器故障诊断方法。对操动机构振动信号进行连续小波变换生成时频图(CWT),并对时频图进行统一压缩预处理;将预处理后的时频图作为特征图输入卷积神经网络AlexNet模型;通过对网络参数的调整,逐步改进网络模型,有监督地实现对操动机构故障状态的辨识诊断。结果表明,该方法能够有效地运用于断路器操动机构故障辨识诊断,与小波频带能量-RBF、小波频带能量-SVM的故障识别相比,故障识别准确率最高。 相似文献
11.
12.
13.
S.‐T. Ung S. Bonsall V. Williams A. Wall J. Wang 《Quality and Reliability Engineering International》2007,23(5):631-639
Greater heed has been paid to the matter of maritime security since the tragedy in the U.S.A. on 11 September 2001. A number of measures have been put into practice by ports to enhance security. More regulations and measures sometimes imply an increased probability of influencing port operations. Thus, the quality of the port security process regulated by measures is becoming essential. In this paper, the quality control in the port security process is demonstrated using the Six Sigma concept. It is concluded that it is crucial to distinguish each step of a security process clearly from the outset, furthermore, gathering quantitative data at each stage is the first priority. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
14.
The rapid evolution of computing and communication technologies and their standardizations have made the boom in e-commerce
possible. Lowering of the cost of operation, increase in the speed of transactions, and easy global reach to customers and
vendors have been the reasons for the overwhelming popularity of this new way of commerce. This article examines the issues
related to the security of the assets and transactions in the e-commerce components and activities. Since large public money
is involved in the transactions, the role of information security and privacy is not exaggerated in this kind of business.
After examining the technologies used in e-commerce, the article goes on to identify the security requirement of e-commerce
systems from perceived threats and vulnerabilities. Then e-commerce security is viewed as an engineering management problem
and a life cycle approach is put forward. How the e-commerce systems can be made secure using the life cycle approach is outlined.
The relevant standards and laws are also discussed in the perspective of e-commerce. The article closes with some future research
directions and conclusions. 相似文献
15.
16.
17.
18.
The domain name system (DNS) provides a mapping service between
memorable names and numerical internet protocol addresses, and it is a critical
infrastructure of the Internet. The authenticity of DNS resolution results is crucial for
ensuring the accessibility of Internet services. Hundreds of supplementary specifications
of protocols have been proposed to compensate for the security flaws of DNS. However,
DNS security incidents still occur frequently. Although DNS is a distributed system, for a
specified domain name, only authorized authoritative servers can resolve it. Other servers
must obtain the resolution result through a recursive or iterative resolving procedure,
which renders DNS vulnerable to various attacks, such as DNS cache poisoning and
distributed denial of service (DDoS) attacks. This paper proposes a novel decentralized
architecture for a DNS data plane, which is called Blockzone. First, Blockzone utilizes
novel mechanisms, which include on-chain authorization and off-chain storage, to
implement a decentralized and trustworthy DNS data plane. Second, in contrast to the
hierarchical authentication and recursive query of traditional DNS, Blockzone
implements a decentralized operation model. This model significantly increases the
efficiency of domain name resolution and verification and enhances the security of DNS
against DDoS and cache poisoning attacks. In addition, Blockzone is fully compatible
with the traditional DNS implementation and can be incrementally deployed as a plug-in
service of DNS without changing the DNS protocol or system architecture. The
Blockzone scheme can also be generalized to address security issues in other areas, such
as the Internet of things and edge computing. 相似文献
19.