位置服务信息安全防护

随着无线通信技术和智能移动终端的快速发展,基于位置的服务(LBS)在军事、交通、物流等诸多领域得到了广泛应用,它能够根据移动对象的位置信息提供个性化服务。在人们享受各种位置服务的同时,移动对象个人信息泄露的隐私威胁也渐渐成为一个严重的问题。为移动用户提供位置服务的同时,保护移动用户的位置隐私也至关重要。本文就位置业务隐私保护技术和位置业务隐私管控手段进行了探讨。     

500kW光伏并网逆变器系统设计

本文介绍了基于IGBT并联,以TMS320F28335DSP为硬件基础的500kW光伏逆变器系统硬件设计及控制策略。     

Identification of preconditions for an emerging mobile LBS market

Location information has become a very important horizontal service component for a wide range of vertical mobile applications. This enabled multiple innovative mobile location-based services (LBS) that range from conventional mapping and navigation services featuring millions of points of interest (POI) to location-aware content delivery and mobile social networking. Providing a whole new world of opportunities for device and application vendors, network operators, content providers and prospective consumers, mobile LBS have potential to become one of the core businesses in today's mobile arena. However, the future of this market is not fully transparent due to several uncertainties associated with a mixture of technologies, service demand, consumer attitude, privacy aspects of using LBS and a complex value network. In this study, we identify and analyse a set of preconditions for an emerging mobile LBS market in its present evolution phase. The history of LBS motivates us to take a closer look at this emerging market and try to understand what the main reasons for LBS initial failure have been and what is still missing in this market today to emerge successfully. To focus on the most relevant issues, we construct our own research framework containing three main dimensions: technological advance and standardisation, value network and value proposition. Within these dimensions, we compare the early state of mobile LBS with the present situation and analyse the key factors presently crucial for LBS proliferation.     

Impact of Galileo commercial service on location-based service providers: business model analysis and policy implications

Today's mobile location-based services (LBSs) largely depend on a free-of-charge, best-effort positioning technology, called global positioning system, which is controlled by the US military. The European alternative Galileo will not only offer a similar best-effort system by 2020, but also a premium-rate service known as Galileo commercial service (CS). Galileo CS is planned to provide higher positioning accuracy, improved security due to signal authentication and service guarantee. While the technology behind Galileo is often studied, the impact of Galileo CS on the LBS marketplace is rarely discussed. In this article, we fill this gap by analysing how improved accuracy, authentication and service guarantee may impact the business models of LBS providers. We do so by interviewing service providers, policy makers and industry experts on what new services would be enabled; technological alternatives that may emerge in the coming years; and organisational and financial issues that service providers face when adopting such a premium-priced positioning signal. We find that a more accurate, secure and reliable global navigation satellite system signal enables a range of new LBSs, although several alternative technologies are emerging that may make Galileo CS obsolete before it is even launched. To convince the LBS providers to adopt Galileo CS, the institution operating Galileo should get governments on board early on for building trust and should consider progressive pricing schemes. Still, service providers are sceptical about adopting Galileo CS, and the hope to recoup any investments in Galileo may thus be in vain.     

Less is more: empirical design criteria for a tourist place recommendation service which decelerates the visiting experience

Tourist recommendation services provide suggestions for places of interest. While the spatial structure of a tourist's visit has been successfully exploited to improve the quality of place recommendations, its temporal structure has not been taken into account so far. This is surprising because the importance of the visitors' time management is well known from tourism research. We present findings of an empirical study that sheds light on the temporal aspects of tourist exploration behaviour and discuss implications for the design of tourist-recommender systems. The data-set consists of interviews, GPS tracks and geo-referenced photo sequences from visitors of a typical Middle European destination for cultural tourism. Among the results relevant to place recommending are the following: (1) the set of places is often replanned during the visit; (2) comparing place popularity based on photo frequency and place popularity based on staying time, we found notable differences in rank ordering; and (3) the photo frequency and the detour sinuosity of the GPS tracks are decreasing slowly over time. We interpret this last finding as a time-geographic cone effect. Based on the empirical results, we discuss the implications for the design of tourist-recommending services and propose a corresponding user interface utilising a recommendation strategy that tries to counterbalance the time-geographic cone effect, that is, to decelerate the visiting experience.     

家庭网关承载综合业务研究

近年来．家庭市场发展迅速,电信运营商力求通过资源盘活、技术改造、产品创新等手段来满足家庭客户不断增长的通信及信息化需求．而家庭网关承载综合业务正是运营商为实践这一目标而进行的重要探索。本文采用理论与实践相结合的研究方法,首先对家庭网关市场前景及产业链发展进行了介绍,其次分析了家庭网关所能承载的主要业务及其网络服务质量指标要求．最后给出了运营商在大规模部署家庭网关前现网改造需考虑的因素及建议。全文以发展的眼光,从市场前景、业务需求、现网技术改造及应用等几个角度,对运营商利用家庭网关承载综合业务进行研究．为全国家庭网关项目建设决策提供依据。     

C波段400MHz带宽多注速调管的研制

介绍了一种C波段多注速调管的研制。该管工作在矩形腔高次模式,设计目标是在400MHz工作频率范围内输出200kW脉冲功率,工作比3%,采用周期反转永磁聚焦。该管由9个谐振腔构成群聚段,多级滤波器加载双间隙谐振腔构成输出回路。本文介绍了设计方案中的一些考虑、部分模拟计算、扩展带宽的措施和实际制管结果,并指出进一步研制方向。     

大功率宽带耦合腔行波管

介绍了我们近期研制的等激励、带宽达 1 4%的大功率宽带耦合腔行波管的情况 ,对该耦合腔行波管的设计特点、结构特点作了较详细的介绍 ,还对设计该类型管的关键技术进行了分析。     

Should mobile Internet be an extension to the fixed web? Fixed-mobile reinforcement as mediator between context of use and future use

As the fixed and mobile Internet are converging, the question emerges whether consumers expect mobile Internet services to replicate services they know from the fixed Internet. Literature on reinforcement and displacement suggests that the use of new media depends on whether users are inclined to replace or reinforce their existing media use on a new device. This paper analyzes whether the importance that users attribute to using similar services on their mobile phone as on the fixed Internet can explain the intention to adopt mobile services. Specifically, we investigate if such fixed-mobile reinforcement could mediate the impact of personal innovativeness and several dimensions of context. We compare basic Internet services, entertainment services and transaction services. We find that especially the intention to adopt basic Internet services largely depends on the importance of using similar services in the mobile domain as on the fixed Internet. Several context-of-use predictors are partially or even fully mediated by fixed-mobile reinforcement. The results convey a positive message to operators that are betting on converged multimedia services that can be accessed from any device and from any fixed or mobile network.     

宽带城域网及其增值业务

城市信息化离不开城市信息高速公路 ,宽带城域网的建设为城市信息化提供了高速通道。IP网和ATM网将是宽带城域网的核心平台 ,宽带接入技术将成为城域网接入的主要手段 ,宽带城域网整体解决方案离不开IP软技术的应用 ,三网融合将是宽带城域网发展方向。增值业务是网络不断发展的动力所在