A comparison between high-pass and low-pass \Updelta\Upsigma modulators

In this paper, high-pass (HP) $\Updelta\Upsigma$ modulators are compared against the traditional low-pass (LP) $\Updelta\Upsigma$ modulators. The objective of this comparison is to point out the advantages and drawbacks of the two modulators thereby allowing choosing the most suited for a given application. The metrics of comparison are the noise floor, power consumption, area and the effect of the non-idealities of all the basic blocks (i.e., operational transconductance amplifier, quantizer, switches and clocks). The comparative analysis shows that HP modulators are more suited for narrow band applications because of their immunity against DC-offset and flicker noise. For medium and wide band applications, LP modulators are preferred because of their higher robustness against switch imperfections and clock jitter.     

A survey of mobile cloud computing: architecture,applications, and approaches

Together with an explosive growth of the mobile applications and emerging of cloud computing concept, mobile cloud computing (MCC) has been introduced to be a potential technology for mobile services. MCC integrates the cloud computing into the mobile environment and overcomes obstacles related to the performance (e.g., battery life, storage, and bandwidth), environment (e.g., heterogeneity, scalability, and availability), and security (e.g., reliability and privacy) discussed in mobile computing. This paper gives a survey of MCC, which helps general readers have an overview of the MCC including the definition, architecture, and applications. The issues, existing solutions, and approaches are presented. In addition, the future research directions of MCC are discussed. Copyright © 2011 John Wiley & Sons, Ltd.     

超声共沉淀法合成锂离子电池正极材料

采用超声共沉淀法,合成尖晶石型掺杂锰酸锂Li1.05Co0.10Ni0.10Mn1.80O4前驱体,并使用三段热处理方式,制备出尖晶石产物。用粒度分布、XRD、SEM、EDS及电化学性能测试等对其进行表征。结果表明:与未处理试样相比,超声共沉淀法制备的产物的粒度分布变窄,体积比表面积由7.0116m2/cm3缩小至6.9789m2/cm3,晶格常数从0.822nm缩小至0.821nm,晶粒尺寸从67.41nm减小至57.78nm,晶形更加完整,颗粒均匀性更好。经装配成电池测定电化学性能,其充放电平台增长,比容量加大,循环性能更优越。     

基于CAN总线智能查线仪的设计与实现

提出了一种基于CAN总线的智能查线仪的设计和实现方案。将现场可编程芯片、AVR微处理器用于查线设备,使用CAN总线与计算机通信方式来实现各查线模块间的数据通信和结构连接,并通过软件设计来识别有大数量待测端子情况下所需硬件上查线模块的扩充和指定待测查线端点数量,有效地解决了以往各类查线设备缺乏灵活性、扩展性差的问题,能够适应多种场合的不同需求,为各种线缆电气连接关系的检查提供了一种新的解决方案。     

一种基于误差系统稳定性的混沌广义同步方法

该文在将混沌系统分为线性与非线性两部分的基础上,利用反馈控制及参数变换,提出了一种新的混沌广义同步方法。该方法基于线性变换,把系统广义同步问题转化为同步误差系统的稳定性问题,并给出了广义同步存在的条件。该方法可以通过配置同步速度,改善混沌广义同步的性能。且不受混沌系统线性部分稳定性的限制,扩大了混沌广义同步的通用性。通过对Lorenz系统进行仿真,结果表明该方法具有很好的适用性。     

Simulation of Active-Matrix Electrophoretic Display Response Time Optimization by Dual-Gate a-Si:H TFT With a Common Gate Structure

Large off-state drain-source current of the thin-film transistor (TFT) in active-matrix electrophoretic display (AMEPD) pixel leads to dramatic data voltage degradation, which causes severe crosstalk and undesired large response time. In this paper, the leakage current influence on response time is investigated and simulated. A compact model of response time t versus off-state drain-source current I _off is established. The simulation result induces that by reducing I _off the response time can be efficiently shorted. In order to reduce the off-state current, dual-gate amorphous silicon (a-Si:H) TFT with a common gate structure is discussed. Its current regulation mechanism is illustrated, and its fitness for driving the AMEPD pixel is explained. The SPICE simulation results prove that except reducing the crosstalk, dual-gate a-Si TFT can also significantly short the response time by cutting down the off-state current under the operation conditions of AMEPD application, while insignificantly reduces the on-state current.     

二维非线性时域有限差分法分析微孔激光器出射光的近场特性

微孔激光器(VSAL)作为应用于近场光存储系统中的一种新型光源,它的出射光斑的近场特性对于近场光存储是十分重要的。运用二维非线性时域有限差分法(2D-NL-FDTD)分析VSAL出射端即微孔金属膜的近场光学性质,模拟计算了不同参数的微孔金属膜的光强近场分布,对所得结果加以分析,从光学性质的角度,讨论其在近场光存储中的应用,并给出反映其近场光学特性的相关数据。     

UPTIME: an IMS-based mobility framework for next generation mobile networks

Seamless inter-technology mobility is one of the fundamental requirements of next generation mobile networks. For seamless mobility, handover delay and packet loss should be minimized. However, existing solutions suffer from a number of shortcomings in satisfying these requirements: first, handover preparation schemes fail to minimize the handover delay as much as possible. Second, minimizing packet loss which is usually using soft handover (SHO) schemes are excessively wasteful of scarce resources. In this paper, we propose the uninterrupted proactive connection transfer for IMS mobility enhancement (UPTIME) mobility framework which achieves seamless mobility while minimizing excessive power and radio resource consumption. UPTIME incorporates two mechanisms; a proactive handover preparation method and an optimized SHO technique for handover execution. We demonstrate the benefits of the proposed framework through both analysis and simulation. Our simulation results for typical LTE/WiMAX handovers show that the handover preparation delay can be reduced by 70 %, and good packet loss performance can be achieved whilst saving 43 % of radio resources and 48 % of battery power.     

多高超声速导弹协同末制导律及可行初始位置域研究

针对多高超声速导弹以指定落角对目标进行饱和攻击的问题,提出一种具有攻击角度和攻击时间约束的末制导律,并基于此对导弹的末制导可行初始位置域进行研究。建立三维空间导弹运动模型,分别通过纵向通道和侧向通道制导指令实现落角和攻击时间控制,构成三维协同末制导律。考虑导弹过载和末速约束,采用上述制导律,以导弹末制导初始位置的坐标为设计变量,以实际攻击时间与理想攻击时间差为性能指标函数,建立并求解优化模型,得到导弹一维及二维可行末制导初始位置域。仿真结果表明:该三维协同制导律可使多导弹在同一指定时间以指定落角命中目标; 该位置域求解方法可求得给定约束条件下的各导弹末制导可行位置域。     

基于ARM的文本独立笔迹鉴别系统设计

笔迹鉴别是通过分析手写笔迹信息来判断书写者身份的特征分析技术,为提高笔迹鉴别的科学性和准确性,设计了基于ARM嵌入式系统的文本独立（Text-independent）笔迹鉴别系统。系统包括笔迹采集端、数据传输部分和上位机处理端3个部分。首先给出了总体设计和详细的工作流程,并对笔迹信息采集模块和数据传输部分进行分析,最后结合笔迹图像预处理技术和纹理特征分析方法,采用基于多维度Gabor变换和支持向量机（Support Vector Machines,SVM）方法进行实时笔迹鉴别。实验表明,系统鉴别率高,达到了良好的预期效果。