2.5G通信技术GPRS任务处理结构

对于数据应用来说，传统的电路交换浪费了宝贵的频率资源，而分组交换在数据应用方面对频率的利用效率要高的多。文中分析了新的EGPRS（Enhanced General Radio Packet Service）移动终端的主要任务处理，以便读者从移动设备终端角度对2.5G的通信协议有一个认识。     

Effects of Key Drivers on Continuing to Use Digital Convergence Services: Hierarchical Component Approach

Technological advances made with the development of digital technology and the Internet have led to the emergence and evolution of digital convergence — the integration of media and communications. This, in turn, has led to the creation of the representative broadcast and communication convergence business model (IPTV service). This study examines the consumption patterns and behaviors of IPTV service customers and explores the process of their continuous use of the IPTV service, thereby endeavoring to contribute to the diffusion of digital convergence services. To survey customers' continuous use of the IPTV service, this study first designs a research framework based on an examination of the existing literature on satisfaction, loyalty, and so on. In addition, research is conducted on the switching barrier of the method of consolidating customers' adherence to a given IPTV service by increasing the burden on them, thereby developing a final research model with which to attempt yet another heterogeneous approach. This enables not only an analysis of the causal relationship with antecedent variables but also a measurement of the explanatory contribution of the antecedent variables' sub‐variables.     

Ku波段GaN大功率单刀双掷开关设计

基于开关器件的基本工作原理和设计方法,设计了一款GaN大功率Ku波段单刀双掷(SPDT)开关,并着重讨论了GaN大功率开关的耐功率能力.经制作得到不同栅指数、不同单指栅宽的GaN开关器件,测试了其基本性能,并比较了开关器件在GaN工艺与GaAs工艺下的性能差别.Ku波段SPDT开关实测S参数表明,插入损耗小于0.9 dB,隔离度大于27 dB,同时能够承受10W的连续波输入功率;适当牺牲耐功率能力可提升小信号的性能.这款开关可搭配GaN功率放大器与低噪声放大器用于收发组件前端.其尺寸仅有2.0 mm×1.4 mm,满足系统小型化的需求.     

高频变压器分布参数的实验研究

高频变压器是开关电源最重要的组成部分,在系统中起着能量传输、电压匹配以及电路隔离的作用。因此在大功率开关电源中高频变压器性能的好坏是整个系统设计的关键。针对高频变压器性能中分布参数对系统带来的不利影响,在传统变压器模型的基础上建立了高频变压器的电路等效模型,通过理论分析高频变压器分布参数的变化规律,得出减小变压器漏感与分布电容的具体措施。最后通过实验证明这些措施对于变压器分布参数起到了较好的抑制作用。     

一种基于BGP/MPLS的VPN设计与实现

BGP/MPLS VPN具有良好的可扩展性和灵活性,是目前发展最为迅速的VPN技术之一。首先分析了BGP/MPLS技术的VPN模型,对BGP/MPLS VPN的基本原理进行介绍,然后在基于ATM框架下最大限度地兼顾原有控制平面,在上层控制平面少量修改的情况下,有效地利用内部虚拟 MAC地址信息将控制平面和转发平面有机联系起来,在不支持MPLS标签交换的交换芯片上实现VPN报文转发,并提出了一套完整的设计和实现方案。     

近红外量子通信网中单光子波长交换研究

提出了一种新的近红外多用户量子密钥分发中波长交换方案,解决了量子网络中信息交互难题;分析了交换过程中近红外单光子束的偏振变换;仿真了波长交换效率和泵浦光功率之间关系.仿真结果表明,该方案可行并且高效.     

Dynamic switching based real-time routing in low-duty-cycle wireless sensor networks

The dynamic switching based real-time(DSRT)routing protocol was proposed to handle the arbitrary end-to-end(E2E)real-time communication in the low-duty-cycle wireless sensor networks.Firstly,the concept of available speed was designed to compensate for the big sleep latency and facilitate discovering the routes with less latency based on two-hop neighbors’ information(at lease about 20% routing path with less latency was discovered by DRST in the experiments).Moreover,it was noticed that the congestion extent in the low-duty-cycle network was determined not only by the number of packets in the network output queue,but also the destination of the packets.However,the traditional method with one-hop neighbors’ information cannot differentiate this kind of congestion.Therefore,combined with the dynamic switching mechanism,the DSRT proposed a congestion avoiding algorithm by classifying the packets in the queue.Through comprehensive experiments,the efficiency of routing discovering and congestion avoiding of the DSRT protocol is demonstrated,and the E2E delay is decreased by at least 200% when the traffic was high.     

负性液晶在FFS模式下的残像研究

图像残像是评价画面质量的最重要因素之一,大部分工程师研究了组合物的材料和液晶面板的制造工艺,以改善影像残留,但之前的研究主要是以正性液晶材料为基础进行探讨的,本文主要以负性液晶材料为基础研究了用边缘场驱动的面板残像。首先为了比较正性液晶与负性液晶,测量了离子密度及电压保持率(VHR),其次为了比较两种配向材料(PI)与液晶材料的搭配特性并选择合适的组合,量测了样品的直流残留(RDC)电压和Vcom电压随时间的变化。从量测结果可知,紫外(UV)光照前负性液晶离子密度是正性液晶的39倍,经过紫外光照,后负性液晶的离子密度为560Pc/cm,且其紫外光照后电压保持率变化量为2.7%;使用负性液晶搭配PI1的样品A-1的直流残留电压和Vcom(等效为交流驱动电压的中心值)随时间变化量都是最大的,分别为0.5V和250mV,负性液晶搭配PI2材料的面板和正性液晶的面板的直流残留电压均小于0.2V,其Vcom随时间变化量均在50mV以内。负性液晶材料的离子浓度含量高,且其稳定性比正性液晶材料差,负性液晶材料比正性液晶材料更容易发生残像;对于使用负性液晶材料,边缘场驱动模式的面板,搭配PI2配向膜材料能够保持低的直流残留电压及低的Vcom电压变化量,从而对改善残像现象有帮助。     

Electrochemical structure‐switching sensing using nanoplasmonic devices

In this article, the implementation of electrochemical plasmonic nanostructures functionalized with DNA‐based structure‐switching sensors is presented. eNanoSPR devices with open and microfluidic measurement cells are developed on the base of nanohole arrays in 100 nm gold film and applied for combined microscopic and electrochemical surface plasmon (eSPR) visualization. eSPR voltammograms and spectroscopy are performed using planar three electrode schematic with plasmonic nanostructure operated as working electrode. Limit of detection of eNanoSPR devices for oligonucleotide hybridization is estimated in the low nanomolar and applications for structure‐switching electro‐plasmonic sensing in complex liquids are discussed.