移动运营商在3G价值链上的战略定位

3G时代，差异巨大的用户要求和全新的产业价值链，导致运营商会采取比较复杂的商业模式、竞争策略、业务发展策略以及合作策略。在此过程中，明确移动运营商在3G价值链上的战略定位非常重要。移动运营商可以根据目标客户特征决定战略定位，也可以根据价值环节增值幅度决定战略定位。根据目标客户特征决定战略定位主要有管道提供商定位模式和增值服务提供商定位模式两种。具体采用什么定位模式取决于运营商的发展战略；根据价值环节增值幅度决定战略定位的主要依据是移动数据业务收入在各环节的价值分配情况，取决于价值链上各参与者的力量对比。     

垃圾桶算法模型的理论分析

本文在理论上给出了垃圾桶算法的数学模型,该模型能够从任意给定的系统参数设置,推导出垃圾桶系统的各个参数,并具有计算简单的特点.本文通过将理论计算与仿真结果的比较,验证了本文所提出的模型确实是一个具有良好计算精度的实用化模型.为了建立垃圾桶算法的数学模型,本文研究了早期随机丢弃RED(Random early discard)系统的平均丢失率与平均队长的相互关系的理论问题,有效的解决了从平均丢弃率估计RED平均瞬时队长的问题.     

基于MoO3和Re-Bphen修饰有机太阳能电池性能的研究

有机太阳能电池(OSCs)的性能与材料及器件结构密切相关。以MoO3为阳极缓冲层,有机金属配合物Re-Bphen为阴极缓冲层,制备了结构为ITO/MoO3/CuPc/C60/Re-Bphen/Al的OSCs。在标准太阳光照条件下,当MoO3和Re-Bphen的厚分别为5nm和8nm时实现了器件的最佳性能,能量转换效率(PCE)和器件寿命均显著提高。结合器件结构,分析了工作机制。     

具有反馈式光缓存的OPS节点结构性能研究

对反馈式光分组交换节点的性能进行深入分析,并针对现有反馈式光分组交换节点结构的不足,提出一种改进的反馈式光分组交换节点结构,即SMOP-TWC交换结构.最后,本文使用仿真实验的方法对SMOP-TWC交换结构的性能进行深入研究.     

Two new analog multipliers/dividers employing single current differencing buffer amplifier

This paper presents two new analog multipliers/dividers using a new universal active element, called the current differencing buffered amplifier (CDBA). The reported circuits are suitable for monolithic chip realization for use in battery-powered, portable electronic equipments. The circuits can be used as a multiplier and divider without changing circuit topologies. The workability of the proposed configurations is tested through different applications with PSPICE simulations using TSMC 0.35 μm CMOS process parameters. The simulated results show that: for ±2.5 V power supply, the total harmonic distortions are less than 3.1% and 2.25% for the first and second configuration respectively. It also shows that the −3 dB bandwidths are 59.09 MHz and 68.55 MHz and static power dissipations are 0.28 mW and 0.23 mW respectively. The sensitivity of the output of the circuits is low with respect to temperature variations.     

供应链金融视角下的小微企业信用风险评价

近年来,随着小微企业融资难的问题日益凸显,供应链金融作为新的融资渠道,正受到越来越多的重视,科学、准确的风险评价对控制供应链金融中的信贷风险至关重要。通过建立和完善小微企业信用风险评价指标体系,采用BP神经网络模型为小微企业信用风险评价开辟新途径。BP神经网络是一种智能算法,它具有自我学习和自适应的特点。通过实例,分析和检测了该BP神经网络模型,结果令人满意。证明该模型确实可行,能够应用于供应链中各小微企业的信用风险评价。     

A low-power,fast-settling reference circuit for high-speed high-resolution ADC

A low-power, fast-settling reference buffer used for high-speed high-resolution ADC is proposed. A replica buffer forms a closed loop to stabilise the operating point and a cascaded gm-boosting technique provides sufficient low output impedance, all of which ensure a high performance for the proposed buffer. The measured results show that the proportion of power consumption by the proposed buffer over ADC is only 2.7%, while settling to 12-bit accuracy within 0.13 ns.     

移动互联网产业链简析*

本文首先论述了移动互联网发展阶段,对其不同于PC产业的垂直整合生态模式进行了分析。之后,就移动互联网产业链进行了全面的分析,囊括云计算、应用、网络、设备制造、软件、硬件等诸多环节。最后对国际和我国移动互联网产业链主要环节的发展情况、局限和方向进行了判断。     

Dynamic multicast link selections for buffer‐aided relaying networks

The management of small cell is considered a key point in next‐generation cellular networks for providing higher data rates, and the relay nodes are expected to be useful to improve the coverage area. Moreover, multicast services have gained importance to disseminate common data to subscribers. The use of buffer‐aided relay for multicast communications is analysed in the paper, and different policies to perform the optimal link selections are compared. These policies are based on the knowledge of the instantaneous link quality indicators as well as the status of the relay buffer and dynamically select the better link according to a suitable probabilistic criterion by improving the aggregate multicast flows. The parameters of these multicast policies are optimized via a Markov chain theoretical framework. The performance for all the proposed methods is analytically derived and validated through computer simulations conducted in different multicast scenarios. The advantages of the proposed schemes are pointed out in terms of multicast throughput, buffer occupancy for different buffer and multicast group size. Copyright © 2016 John Wiley & Sons, Ltd.     

聚乙二醇阴极修饰层改善聚合物太阳能电池光电性能的研究

通过将聚乙二醇(PEG)掺入活性层制备聚合物太阳 能电池,利用PEG的迁移特性获得阴极修饰层,研 究PEG阴极修饰层对聚合物太阳能电池光电性能的影响。X射线光电子能谱(XPS)分 析表明,掺入活性层中的 PEG迁移到活性层与Al电极之间,形成了阴极缓冲层。吸收光谱、电流密度-电压 特性曲线和外量子 效率谱的分析表明,PEG阴极缓冲层的形成改善了活性层与阴极的界面接触特性, 降低了活性层与电 极之间的能级势垒,有利于载流子传输,因此显著地改善了聚合物太阳能电池的光电性能, 使得器件的开 路电压Voc、短路电流密度Jsc和填充因子(FF)都有明显提高。当P3HT:PCBM 活性层中掺入体积比为0.5%的PEG时,聚合物太阳能电池的能量转换 效率(P CE)最高,达到了3.07%,比未掺杂PEG的参考器件提 高了38.5%。