Estimating user interaction strength in distributed online networks

User interactions are indispensable for any online network to thrive, especially for BitTorrent‐like and Web real‐time communication‐based distributed online networks that rely on users' collective contributions instead of the help of central servers. User interactions provide fine‐grained information for many applications, such as security enhancement and cooperation promotion. To date, several schemes for estimating user interaction strength in centralized online networks have been proposed. In contrast, we present design, deployment, and analysis of UISE for user interaction strength estimation in distributed online networks. Among the strong points of UISE is that it captures both direct and indirect user interactions, and that it scales with only partial information dissemination. We apply UISE to devise the first distributed scheme for online time estimation and we implement it into Tribler, a distributed online network for media and social applications like file sharing, streaming, and voting. We demonstrate the accuracy and the scalability of UISE with different information dissemination protocols and user behaviors using simulations, emulations, and a real‐world deployment. Copyright © 2015 John Wiley & Sons, Ltd.     

基于用户体验延迟的QoE层次评估模型

针对Web服务中难以获得反映用户体验的数据,且难以对用户体验质量（QoE）进行评估的问题,在分析了Web数据和现有评价方法的基础上,提出了一种融入用户体验延迟ED的QoE层次评价方法。该方法基于层次分析法,并结合人类生理主观感受,能够更加客观地衡量用户体验。通过相关案例验证了该方法的可行性。     

移动互联网下视频时延的用户体验质量研究

随着移动互联网的发展,移动视频业务的迅速爆发,良好的用户体验质量(QoE) 成为运营商挽留用户的关键因素。从用户体验角度,建立不同时延下移动视频业务的评价量化 标准。通过情景实验模拟的方法,以平均主观意见分(mean opinion score,MOS)量表建立用户 视频体验质量的实数映射关系。针对用户对视频观看时延的有效反应进行分级研究,得到以下 结果：单次和多次的初始缓冲时延和卡顿时延对用户观看移动视频的影响并建立用户体验质量 评价等级。在短视频中出现单次时延在4 s 以上,用户会出现负面情绪;在相同延迟时长下, 单次的初始缓冲时延的用户体验质量略优于卡顿时延;对于在一定播放时长的移动视频业务中 出现多次卡顿,卡顿时延短但是间隔频繁的体验质量比卡顿时延长但是间隔时间长的体验质量 要更差。     

A novel user identification scheme with key distribution preserving user anonymity for distributed computer networks

Recently, Yang et al. proposed an efficient user identification scheme with key distribution, in which it is possible for the user to anonymously log into a system and establish a secret key shared with the system. Mangipudi and Katti later demonstrated a Deniable-of-Service (DoS) attack on the Yang et al. scheme and then proposed an improvement to withstand such an attack. However, this paper demonstrates an identity disclosure attack to show that neither schemes’ claimed user anonymity requirement can be achieved. We further propose a novel user identification scheme with key distribution preserving user anonymity for distributed computer networks. The proposed scheme not only withstands the attacks mentioned above, but also achieves the following: (i) user anonymity, (ii) key distribution, (iii) mutual authentication, and (iv) key confirmation. The performance of our scheme is of greater efficiency than that of previously proposed schemes in terms of communication costs and computational complexities.     

一类基于微分方程模型具有连续分布延迟神经网络的稳定性分析

考虑一类基于微分方程具有连续分布延迟的神经网络模型。利用Lozinskii方法的性质和微分不等式方法,获得了这类具有连续分布延迟的神经网络的渐近稳定的一些充分条件,结果去掉了对激励函数有界性的要求。     

The effect of network delay and media on user perceptions of web resources

This research experimentally examines the effects of network delays, document type, and various user characteristics on the perceived usability of distributed documents on the internet. Six experimental conditions were analysed: text only documents and documents including text and graphics at three levels of delay. Users were undergraduate and graduate students who reported spending zero to 50 hours per week on the internet. Usability was assessed by analysing responses to questions about ease of locating information, information organization, information quality, and navigation problems. The results showed significant interactions of network delay and document type on subjects' perceptions of quality, organization, navigation, and several additional factors that are important to organizations providing information on the internet. Both the number of hours subjects reported spending using the internet and subjects' self-reported command of the English language were significantly correlated with perceptions of various aspects of the internet sites examined. While the results indicate that internet users may prefer highly graphical web sites, it appears that they are unwilling to tolerate substantial delays. As a result, users in the study preferred plain text documents as delays increased.     

The effect of network delay and media on user perceptions of web resources

This research experimentally examines the effects of network delays, document type, and various user characteristics on the perceived usability of distributed documents on the internet. Six experimental conditions were analysed: text only documents and documents including text and graphics at three levels of delay. Users were undergraduate and graduate students who reported spending zero to 50 hours per week on the internet. Usability was assessed by analysing responses to questions about ease of locating information, information organization, information quality, and navigation problems. The results showed significant interactions of network delay and document type on subjects' perceptions of quality, organization, navigation, and several additional factors that are important to organizations providing information on the internet. Both the number of hours subjects reported spending using the internet and subjects' self-reported command of the English language were significantly correlated with perceptions of various aspects of the internet sites examined. While the results indicate that internet users may prefer highly graphical web sites, it appears that they are unwilling to tolerate substantial delays. As a result, users in the study preferred plain text documents as delays increased.     

Cooperative user–network interactions in next generation communication networks

Next Generation Communication Networks employ the idea of convergence, where heterogeneous access technologies may coexist, and a user may be served by anyone of the participating access networks, motivating the emergence of a Network Selection mechanism. The triggering and execution of the Network Selection mechanism becomes a challenging task due to the heterogeneity of the entities involved, i.e., the users and the access networks. This heterogeneity results in different and often conflicting interests for these entities, motivating the question of how they should behave in order to remain satisfied from their interactions. This paper studies cooperative user–network interactions and seeks appropriate modes of behaviour for these entities such that they achieve own satisfaction overcoming their conflicting interests.     

延迟容忍网络的安全网络编码方案

当前针对污染攻击的解决方案需要公钥基础设施支持,但这对于移动Ad hoc网络而言并不可取,因此提出了无需公钥基础设施的网络编码方案。所提方案允许数据包相互验证,从而使中间节点可判断这些包是否可以未经源验证即可共同编码。分析和比较了其他签名方案,表明无需公钥的网络编码签名功能足以防止污染攻击。     

社交网络用户影响力分析ABP算法研究与应用

社交网络作为一种交往方式,已经深入人心。其用户数据在这个大数据时代蕴藏着大量的价值。随着Twitter API的开放,社交网络Twitter俨然成为一个深受欢迎的研究对象,而用户影响力更是其中的研究热点。PageRank算法计算用户影响力已经由来已久,但是它太依赖于用户之间的关注关系,排名不具备时效性。引入用户活跃度的改进PageRank算法,具备一定的时效性,但是不具有足够的说服力和准确性。研究了一种新的基于时间分布用户活跃度的ABP算法,并为不同时段的活跃度加以相应的时效权重因子。最后,以Twitter为研究对象,结合社交关系网,通过实例分析说明ABP算法更具时效性和说服力,可以比较准确地提高活跃用户的排名,降低非活跃用户排名。     

Modeling user experience: A case study on a mobile device

User experience (UX) consists of all aspects of interactions between a user and a product. Recently, many studies have been conducted to define the UX concept, but few studies have attempted to quantify UX. This paper proposed quantification models that integrate major elements of UX into a single index. A variety of models were proposed and evaluated including compensatory (i.e. simple linear, polynomial and S-shaped value) and non-compensatory (i.e. conjunctive and disjunctive) models. A case study with a commercial tablet PC was conducted in which a total of 26 subjects participated in a laboratory environment. Each participant performed a pretest ensuring the ability to make ratio judgments and then evaluated predefined dimensions with the modified magnitude estimation procedure. A total of 22 hierarchical dimensions were evaluated such as overall UX, its elements (i.e. usability, affect and user value) and sub-elements. Both compensatory and non-compensatory models had high performance in terms of goodness of fit. The results of this study are expected to help product or service designers develop indices representing an overall UX value.Relevance to industryThis study proposed quantification models that aggregate elements of UX. Although the UX index has been controversial, the single value developed by the models can be expected to help decision-makers understand about products or services intuitively.     

Modeling and distributed simulation of a broadband-ISDN network

A distributed approach to communication network simulation using a network of workstations configured as a loosely coupled parallel processor to model and simulate the broadband integrated services digital network (B-ISDN) is proposed. In a loosely coupled parallel processor system, a number of concurrently executable processors communicate asynchronously using explicit messages over high-speed links. Since this architecture is similar to that of B-ISDN networks, it constitutes a realistic testbed for their modeling and simulation. The authors describe an implementation of this approach on 50 Sun workstations at Brown University. Performance results, based on representative B-ISDN networks and realistic traffic models, indicate that the distributed approach is efficient and accurate     

利用主动网技术实现高效的分布式网络管理

随着网络规模的迅速扩大，传统的集中式的网络的缺陷已经凸现，一个灵活高效的网络管理平台应该是分布式，可编程的，文章探讨了把主动网技术应用到网络管理中来实现高效的分布式网络管理，提出了一种新的网络体系结构。     

多域网络中基于时延感知的虚拟网络映射方法

随着各种时延敏感型应用的出现,如何提高系统的时延性能已经成为了学术界的热门话题。然而,现有的多域映射算法很难满足虚拟网络对时延性能的要求。因此,为了解决这一问题,提出了一种基于时延感知的多域虚拟网络映射算法（time delay sensitive virtual network embedding,TDS-VNE）。在节点映射阶段定义了一个节点传播时延评价函数（D）,在链路映射阶段定义了路径时延感知参数。仿真结果表明,提出的映射算法降低了平均网络传播时延且在虚拟网络请求接受率、长期收益成本比等指标上具有良好的效果。     

基于随机网络演算的无线传感器网络延时研究

基于随机网络演算研究了无线传感器网络中延时相关问题,通过随机网络演算建立随机到达曲线和随机服务曲线模型,推导出单个节点和端到端的延时统计界.与节点到节点计算方法的延时界相比,演算方法更为简单.另外,随机延时界比确定性延时界具有更好的包络性,给出了违背界的函数.数值结果表明,运用SNC的卷积公式求得的概率统计型延时边界的结论具有更严格包络性,对无线传感器网络配置和QoS控制具有较强参考意义.     

Towards efficient and practical network coding in delay tolerant networks

Network coding techniques offer an emerging solution to efficient data transmission in Delay Tolerant Networks (DTN). To date, abundant techniques have been developed on exploiting network coding in DTN, however, most of them bring additional overhead due to the extra coded message redundancy. In this paper, we analyze the coded message redundancy issue, and then propose NTC, an efficient network coding scheme for DTN. In NTC, a novel metric named “redundancy ratio” is introduced within the anti-entropy message exchange process. We also discuss the design and implementation of practical NTC in detail. To evaluate the performance of our proposed NTC scheme, we implement NTC in ONE, the current state-of-the-art simulator for DTN. Simulation results show that, comparing with existing schemes, our proposed NTC scheme has significant advantages in enhancing the message delivery ratio and reducing the transmission overhead.     

基于PUF的5G车联网V2V匿名认证与密钥协商协议

单点登录（single sign on,SSO）方案能够避免认证模块冗余带来的资源浪费、信息泄露问题,而具有匿名性的单点登录能够在保护个人隐私的情况下实现匿名认证与授权,但现有的匿名单点登录方案未考虑因用户匿名而出现的欺诈行为追责问题. 针对此问题,首先提出一个格上可追溯的匿名单点登录方案. 所提方案采用格上基于身份的密码体制缓解公钥证书管理问题,通过授权认证标签和假名实现对用户的匿名认证;然后使用强指定验证者技术实现用户服务请求的定向验证;同时引入受信任机构,通过公钥恢复出用户身份并进行追责;最后在安全模型下证明方案具有不可链接性、不可伪造性与可追溯性. 安全性与性能分析结果表明方案在PARMS II和PARMS III这2组参数下,分别运行大约75 ms和108 ms便可为用户生成可供4次服务请求的访问服务票据,并可达到230 b和292 b的量子安全强度.