Optimal network selection in heterogeneous wireless multimedia networks

The complementary characteristics of different wireless networks make it attractive to integrate a wide range of radio access technologies. Most of previous work on integrating heterogeneous wireless networks concentrates on network layer quality of service (QoS), such as blocking probability and utilization, as design criteria. However, from a user’s point of view, application layer QoS, such as multimedia distortion, is an important issue. In this paper, we propose an optimal distributed network selection scheme in heterogeneous wireless networks considering multimedia application layer QoS. Specifically, we formulate the integrated network as a restless bandit system. With this stochastic optimization formulation, the optimal network selection policy is indexable, meaning that the network with the lowest index should be selected. The proposed scheme can be applicable to both tight coupling and loose coupling scenarios in the integration of heterogeneous wireless networks. Simulation results are presented to illustrate the performance of the proposed scheme.     

Mutual interference considered power allocation in OFDM-based cognitive networks: the multiple SUs case

Power allocation for secondary users (SUs) in cognitive networks is an important issue to ensure the SUs’ quality of service. When the mutual interference between the primary users (PUs) and the SUs is taken into consideration, it is wanted to achieve the conflict-free power allocation while synchronously maximizing the capacity of the secondary network. In this paper, the optimal power allocation problem is considered in orthogonal frequency division multiplexing cognitive networks. The single SU case is primarily formulated as a constrained optimization problem. On this basis, the multiple SUs case is then studied and simulated in detail. During the analysis, the mutual interference among the PUs and the SUs is comprehensively formulated as the restrictions on the SU’s transmission power and the optimization problems are finally resolved by iterative water-filling algorithms. Consequently, the proposed power allocation scheme restrains the interference to the primary network, as well as maximizing the capacity of the secondary network. Specifying the multiple-SUs case, simulation results are exhibited in a simplified scenario to confirm the efficiency of the proposed water-filling algorithm, and the influence of the mutual interference on the power allocation and the system capacity is further illustrated.     

自由曲面LED路灯反射器设计

针对LED路灯反射器设计中存在的中心光强较强、两边渐弱、均匀度不高等问题提出了一种新的V型结构光学反射器,该结构的反射器将每一个路灯覆盖的照明区域等分成两部分.由能量守恒原理建立起LED光源出射光线的角度与照明平面上的坐标的对应关系,根据对应关系计算反射器自由曲面上的点坐标.通过建模软件把诸多点拟合成曲面实体,将实体导入光学软件进行照明仿真.结果表明:该路灯反射器的照度均匀度达到77.85%,可在目标路面上形成照度均匀的矩形光斑.     

基于Nios处理器的FED控制系统设计

FED是新一代真空平板显示器件,具有色彩自然逼真、响应速度快、宽视角、低功耗、矩阵选址等突出优点,应用范围广泛。FED显示控制系统是整个驱动电路的核心,随着分辨率和规模化的提高,需要高速的帧存储器和高速的接口,加速系统的运行速度,减少传输时间。主要介绍了一种采用Nios软核作为中央处理器,进行主要的计算处理、控制各种信号的FED显示控制系统。同时使用FPGA作为协处理器,把一些运算中常用到的耗用大量CPU时钟的运算以Nios软核的形式嵌入到系统中,利用动态可重构的原理实现各个软核函数的分时复用,提高了整个FED控制系统的性能。     

EK1决议选译

德国GS标志是德语"经检测安全"的缩写,表示产品通过德国认证机构的型式检测和批量生产监督.该标志是一个包括电气产品在内的通用产品安全认证标志.GS认证属于自愿性认证.     

高性能表面安装型激光隔离器的研制

基于高斯光束耦合理论,对光斜面耦合的光隔离器回波损耗进行了分析,通过改进核心元件的加工组合工序,采用表面安装技术,研制了光斜面耦合的高性能表面安装型光隔离器,测试结果表明,这种表面安装光隔离器具有优异的性能参数.     

基于K-L变换的两传感器图像自动配准

基于合成孔径雷达(SAR)图像和光学图像间的变形可用仿射变换来近似,提出了一种SAR图像和光学图像自动配准的方案.对分割后的图像进行K-L变换得到两幅图像的主分量与坐标轴之间的关系,从而得出两幅图像的角度关系,接着,利用旋转后图像的横纵象素范围的比值和前景重心偏移值得到仿射变换的缩放和平移参数,最后再利用二值图像相关对仿射变换的结果图像进行精配,从而实现较高精度的图像配准.实验结果表明,在满足精度要求的情况下,本方法可以自动完成具有明显方向性和较大前景目标图像的配准任务.     

Efficient TiO2 Photocatalysts from Surface Hybridization of TiO2 Particles with Graphite‐like Carbon

Surface hybridization of TiO₂ with graphite‐like carbon layers of a few molecular layers thickness yields efficient photocatalysts. Photoelectrochemical measurements confirm an electronic interaction between TiO₂ and the graphite‐like carbon. A TiO₂ photocatalyst with a carbon shell of three molecular layers thickness (～1 nm) shows the highest photocatalytic activity which is about two times higher than that of Degussa P25 TiO₂ under UV light irradiation. The mechanism of the enhanced photocatalytic activity under UV irradiation is based on the high migration efficiency of photoinduced electrons at the graphite‐like carbon/TiO₂ interface, which is due to the electronic interaction between both materials. In addition, a high activity under visible light irradiation is observed after graphite‐like carbon hybridization. TiO₂'s response is extended into the visible range of the solar spectrum due to the electronic coupling of π states of the graphite‐like carbon and conduction band states of TiO₂.     

固网智能化创新业务的研究

固网智能化为PSTN提供丰富业务创造了条件,能进一步挖潜PSTN的潜力,为PSTN赋予了新的活力.本文提出三个固网智能化创新业务:多号彩振、电话广告和变声业务,并在其业务定义、业务功能、技术实现方案、产品定位与目标用户等方面进行了研究.     

数字仿真技术在电子战装备性能评估中的应用

介绍了基于数据流处理的数字仿真技术的基本概念及特点,结合现代电子战装备性能评估的需求,阐述了基于数据流处理的仿真技术在电子战装备性能评估中的具体应用和发展前景.