A unified mobility model for analysis and simulation of mobile wireless networks

We propose a novel mobility model, named Semi-Markov Smooth (SMS) model, to characterize the smooth movement of mobile users in accordance with the physical law of motion in order to eliminate sharp turns, abrupt speed change and sudden stops exhibited by existing models. We formulate the smooth mobility model by a semi-Markov process to analyze the steady state properties of this model because the transition time between consecutive phases (states) has a discrete uniform distribution, instead of an exponential distribution. Through stochastic analysis, we prove that this model unifies many good features for analysis and simulations of mobile networks. First, it is smooth and steady because there is no speed decay problem for arbitrary starting speed, while maintaining uniform spatial node distribution regardless of node placement. Second, it can be easily and flexibly applied for simulating node mobility in wireless networks. It can also adapt to different network environments such as group mobility and geographic constraints. To demonstrate the impact of this model, we evaluate the effect of this model on distribution of relative speed, link lifetime between neighboring nodes, and average node degree by ns-2 simulations.

Me,myself and my mobile: A segmentation of youths based on their attitudes towards the mobile phone as a status instrument

The importance of the mobile phone in the life of adolescents has led observers to speak of a Mobile Youth Culture. One of the central characteristics of this youth culture is the use of the mobile phone as a means to display or enhance one’s status in the peer group. To date, however, little attention has gone out to the different uses adolescents may have for their mobile phones. Therefore, this study aims to further our understanding of the heterogeneity in adolescent mobile phone use by examining whether we can distinguish between different ‘mobile lifestyles’ within the Mobile Youth Culture. Drawing on a quantitative survey among 1943 Flemish adolescents (12–18 years), we differentiated three lifestyles based on their attitudes towards the mobile phone as a fashion article, as a display of one’s popularity and as a display of one’s time scarcity. A two-step cluster procedure based on respondents’ scores on these three mechanisms revealed three different segments: trendy users (N = 603), engaged users (N = 864) and thrifty users (N = 436). These segments showed significantly different profiles in terms of socio-demographics, their use of the mobile phone in the presentation of the Self and the mobile phone’s role in their friendship relationships.     

When lifestyle becomes behavior: A closer look at the situational context of mobile communication

The web is going mobile, and the scope of mobile communication is widening tremendously, thus paving the way for a wide array of new forms of mobile device use. However, not every user is necessarily all the time taking advantage of the expanded affordances of mobile devices. Texting and phoning are still the predominant services in mobile communication. Previous research has argued that different styles of mobile communication are related to different user lifestyles. Thus, a remapping and matching of the landscape of mobile communication in relation to user lifestyles seems necessary. In this paper, we take one step back and first consider the instances in which lifestyles become behavior; i.e. actual usage situations of mobile communication. We outline three empirically deduced types of mobile communication usage situations, as well as three types of mobile web usage situations, to shed light on the instant at which lifestyle becomes behavior; i.e. at which specific usage situations of mobile communication actually occur.     

Adding value to the network: Mobile operators’ experiments with Software-as-a-Service and Platform-as-a-Service models

The environments of software development and software provision are shifting to web-based platforms supported by Software-as-a-Service (SaaS) and Platform-as-a-Service (PaaS) models. This paper will make the case that there is equally an opportunity for mobile operators to identify additional sources of revenue by exposing network functionalities through web-based service platforms. By elaborating on the concepts, benefits and risks of SaaS and PaaS, mobile operators’ experiments are compared and similarities with these models are identified. Based on the analysis of various case studies, this paper argues that mobile operators mobile web services are decisively shifting from SaaS to PaaS models. However, these platforms incorporate fragmentation at several levels and are likely to face future challenges in order to thrive.     

Activation level in boron-doped thin germanium-on-insulator (GeOI): Extraction method and impact of mobility

We hereby present a non-destructive method for extracting the activation level on boron-doped germanium-on-insulator (GeOI) wafers, with a discussion on the impact of the hole mobility model. This method combines Monte Carlo boron profile simulations with optical Ge layer thickness T_Ge and electrical sheet resistance R_sh measurements. As B atoms are known not to diffuse in Ge for the usual activation temperatures (<800 °C), we can assume that the as-implanted dopant profile remains unchanged after annealing (no modelling of boron diffusion required). We highlight that the knowledge of the hole mobility dependence on activated impurities concentration in Ge is of paramount importance. Several experimental and theoretical models are available in the literature. After relative validity assessments, all of them have been implemented for extraction and unfortunately yield different values scattered over nearly one decade. Still, the lower-bound concentration 2.7×10¹⁹ cm⁻³ is in the range of the state-of-the-art values for B-implanted crystalline Ge and has proven suitable for functional GeOI pMOSFET demonstration.     

Exploring the patterns and determinants of the global mobile divide

This study explores the patterns of the global mobile divide and the factors that influenced it. It proposes a comprehensive framework to explain mobile phone adoption by integrating technology acceptance model (TAM) and economic consumption analysis. The empirical analysis is conducted using the data from more than 150 countries. The results show that the gaps of mobile phone penetration among different groups of income level countries have decreased during the past 23 years. Average income had a negative correlation with mobile phone adoption rate, represented by the slope of mobile phone diffusion curve. However, average income had a positive correlation with mobile phone penetration, suggesting that there are still gaps of mobile phone penetration between rich and poor countries. Besides average income, other factors, such as legacy phone system, population density, and education level, were also demonstrated to have influence on mobile phone penetration. The framework and findings of this study suggest the potentials for the integration among consumption analysis, diffusion of innovation theory (DIT), and TAM. Strategies for further bridging the global mobile divide are suggested based on the empirical findings.     

同学网络的拓扑结构研究

基于在线社交网络平台,建立了同学关系网络的初步模型,并结合复杂网络理论相关知识对其拓扑结构进行了研究.在大学生在线社交平台“人人网”上收集相关数据并建立数据库,在此基础上构建相应的社交网络——同学关系网络.研究了该网络的拓扑结构,如度分布、平均最短路径长度、群聚系数、度相关系数等重要统计指标.通过分析发现,该网络具有无标度性和“小世界”特性,并呈现异配模式.同时分析了相关特性形成的机制,并给出初步解释,为相关动力学行为研究提供了实证基础.     

The adoption and use of mobile phone in rural China: A case study of Hubei,China

This paper examines the behavioral and psychological factors influencing the adoption and use of mobile phone in rural China. Based on the diffusion of innovations and perceived needs theory, this research, through a case study of Hubei, China, supports the theoretical model that both behavioral and psychological factors can predict Chinese rural residents’ adoption and use of mobile phone. Psychological factors, however, play a weaker role in rural residents’ adoption and use of mobile phone than do behavioral factors. Moreover, behavioral factors can significantly predict some of the psychological factors. By adding behavioral factors into the theoretical model, this study supplements the perceived needs theory and extends it from urban setting to rural setting. Implications of the findings have been discussed.     

配网结构优化及配网自动化探讨

今天,随着人们生活水平的提高,信息化生活的理念不断引领着人们走向更高要求的生活。无论是城市人群还是农村群体,都表现出现越来越大的用电需求,尤其重视供电可靠性。配电自动化指利用计算机及网络技术、通信技术与电力设备相结合,监测、保护、控制配电网,与用户建立更为密切和负责的关系,提高供电质量。本文则以配网结构方式为切入点,探究其优化方案和配网自动化的实现。     

Luminescence,charge mobility,and optical waveguiding of two-dimensional organic rubrene nanosheets: Comparison with one-dimensional nanorods

Intrinsic characteristics of organic and inorganic nanostructures depend on their physical dimensions (i.e., size and shape) and crystallinity. Here, we compared the nanoscale optical and electrical properties of organic rubrene one-dimensional (1-D) nanorods (NRs) and two-dimensional (2-D) nanosheets (NSs). From high-resolution laser confocal microscope photoluminescence (PL) measurements, the light-emission characteristics of 2-D rubrene NSs varied with the crystalline domain direction, indicating intrinsic PL anisotropy, which was distinguishable from 1-D rubrene single NRs, because of anisotropy π–π stacking molecular arrangements. We also observed the variation of charge carrier mobility depending on the measured directions (i.e., anisotropy of charge transport) in rubrene NS-based field-effect transistors. The optical waveguiding properties of rubrene nanostructures were strongly correlated to the dimensionality of materials and PL anisotropy.     

Towards the fulfillment of 5G network requirements: technologies and challenges

Future 5G networks are expected to have the capabilities of providing extremely high data rates, seamless coverage, massive number of connected devices, low latency, etc., in order to support the internet of things era. The dynamic performance of 5G networks is a key feature for controlling the dense and rapidly changing communication environment. Technical issues such as limited frequency resources, interference, energy consumption, and network management are the main challenges facing 5G networks. This article presents a comprehensive study of 5G networks architecture, technologies, challenges, and possible solutions based on recent advances in technology and research.     

Exploring the relationship between urbanized Malaysian youth and their mobile phones: A quantitative approach

Mobile phones have become a ubiquitous consumer item. This paper aims to explore mobile phone usage, extending work beyond teenage years to examine the role of mobile phones among urbanized Malaysian youth, specifically university students. Four main categories were identified, namely, mobile phone purchasing factors and reasons to use, mobile phone usage and also behavioral issues. A mixed-mode approach involving questionnaire surveys and 24-h diaries were used to gather the relevant data. A total of 417 respondents participated in this study. The salient results indicate respondents in this study consider brand, trend and price to be the three most important purchasing factors while socializing and privacy emerged as the two most important reasons to use mobile phones. Behavioral issues related to addiction and inappropriate use of mobile phones was also observed among the respondents. Gender analysis revealed females to use their mobile phones more to socialize, gossip and as a safety device. The findings of this study could prove to be beneficial to those exploring the mobile phone adoption and usage pattern in a developing country such as Malaysia.     

Evolutionary dynamics of media convergence: Early mobile web and its standardisation at W3C

This empirically grounded article focuses on the standardisation of the mobile accessible Web by the World Wide Web Consortium (W3C). It demonstrates what were the different points of departure for the institutions of different kinds (telecommunications operators, online service providers, software developers, content providers, etc.) that got engaged in this standardisation process. It discusses how the dialogical relationships among these stakeholders shaped the nascent medium. It demonstrates how these dynamics conditioned on different ‘levels’ the processes of both the convergence and the divergence between the desktop and mobile webs and shows how these conflicting processes of convergence and divergence were pursued by different industry groupings – ‘infrastructure enablers’ and content providers.     

Personal network on the Internet: How the socially marginalized stay marginalized in personal network diversity and multiplicity

The Internet by its asynchronous and non-spatial nature may facilitate the diverse and multiple personal networks, but we hypothesize that this network affordance will be heavily influenced by one’s socio-demographic positions. To test this hypothesis, we used a large survey data set of Internet users (n = 3,120) and examined how users’ socio-demographic positions interact with Internet access to shape the affordance of network diversity and multiplicity. We found significant interactive effects, while network diversity, as indicated by homogeneity and heterogeneity, was not directly impacted by social positions. The effects of network multiplicity on personal wellbeing also differed by socio-demographic background. We argue that, without an understanding of socio-demographic disparities, a focus on Internet affordance fails to recognize the social reproduction in the creation and the benefits of personal networks.     

城市光纤CATV网络拓扑结构探讨

简要介绍光纤同轴电缆混合网（ＨＦＣ）的优势,分析ＨＦＣ网的几种拓扑结构及优缺点,并对城市ＨＦＣ网拓扑结构的工程实际进行了探讨。     

Early diffusion of smartphones in OECD and BRICS countries: An examination of the effects of platform competition and indirect network effects

Employing the Gompertz model, this study examines macro-level adoption factors of early smartphone diffusion in OECD and BRICS countries. The results of the data analysis suggest that mobile OS competition, mobile network standard competition, open source OS share (platform openness), and price influence the early diffusion of smartphones in OECD countries. However, in BRICS countries, open source OS share (platform openness) and price are the main factors of smartphone diffusion. As the smartphone market continues to grow, it seems that the effects of mobile platform competition and indirect network effects on smartphone diffusion may co-exist in global smartphone markets. In addition, the results of the data analysis suggest that a platform (standard)-neutral policy is important in the growth stage of smartphone markets.     

The temperature mobility degradation influence on the zero temperature coefficient of partially and fully depleted SOI MOSFETs

The zero temperature coefficient (ZTC) is investigated experimentally in partially (PD) and fully depleted (FD) SOI MOSFET fabricated in a 0.13 μm SOI CMOS technology. A simple model to study the behavior of the gate voltage at ZTC (V_ZTC) is proposed in the linear and the saturation region. The influence of the temperature mobility degradation on V_ZTC is analyzed for PD and FD devices. Experimental results show that the temperature mobility degradation is larger in FD than in PD devices, which is responsible for the V_ZTC decrement observed in FD instead of the increment observed in PD devices when the temperature increases. The analysis takes into account temperature dependence model parameters such as threshold voltage and mobility. The analytical predictions are in very close agreement with experimental results in spite of the simplification used for the V_ZTC model as a function of temperature in the linear and the saturation region.     

中小型城市GSM无线网络结构分析与优化

随着移动网络的逐年建设与业务量的不断增长,无线网络结构逐渐趋于复杂,本文主要对中小型城市的无线网络结构分析方法和优化策略进行了研究,通过重叠覆盖度指标情况,对重叠覆盖较高的地区应用天线挂高合理性调整、天线覆盖方向合理性调整、小区覆盖范围调整等优化手段,解决了网络中存在的结构性问题.     

计算机网络安全标准体系结构及对策研究

计算机网络的发展，加快了企业和社会信息化进程，同时也带来了许多网络安全问题。因此，在发展Internet／Intranet网的应用时，更应注意其安全保密。本文主要讨论了网络安全性问题，说明了网络安全体系结构及其关键技术。