基于RFID和ZigBee技术的物联网实验系统硬件设计与实现

基于射频识别技术(Radio frequency identification technology,RFID)和近距离无线组网通讯技术(ZigBee:紫蜂)这两大物联网关键技术,设计以ZigBee协议作为传输协议的物联网主从节点以及RFID读写模块,得到了物联网实验系统的总体方案,并实现了一套完整的物联网实验系统硬件平台.测试结果验证了该实验系统完全满足设计要求,可以应用于教学实验,也可作为其他物联网应用系统的开发.     

一种具有84.8dB SFDR和72dB SNDR的14位80MS/s CMOS模数转换器

本文描述了一种基于0.35μm CMOS工艺的14位采样率80MS/s的流水线型模数转换器的设计. 所提出的电荷分享校正技术消除了与信号相关的电荷注入效应, 加上片内的低抖动时钟电路, 保证了模数转换器的高动态性能. 一种信号电容开关技术和高对称版图减小了电容失配, 确保了模数转换器的总线性度. 测试结果表明, 该模数转换器在36.7MHz输入频率下, 实现了11.6位的有效位, 84.8dB的无杂散动态范围(SFDR), 72dB的信号噪声失真比(SNDR), 在无校准情况下获得了＋0.63/－0.6 LSB的微分非线性和＋1.3/－0.9 LSB的积分非线性. 输入频率200MHz时,仍然可以保持75dB的SFDR和59dB的SNDR.     

微腔中nc-Si/SiN超晶格的光致发光

研究了一维光子晶体微腔结构对nc-Si/a-SiNz超晶格发射的调制.一维光子晶体微腔采用两种具有不同折射率的非化学组分非晶氮化硅的周期调制结构,腔中嵌入采用激光晶化方法制备的硅量子点阵列,从Raman谱和透射电子显微镜分析得到其尺寸约为3～4 nm.从光致发光谱上观察到明显的选模作用、明显变窄的发光峰以及约两个量级的发光强度的增强.微腔对硅量子点阵列发光的调制主要表现在两个方面:共振模式的增强和非共振模式的抑制.硅量子点中位于腔共振模式的辐射跃迁被增强,非共振模式的辐射跃迁被抑制,因此位于腔共振频率处的跃迁通道成为硅量子点中唯一的辐射跃迁通道,导致光致发光谱的窄化和强度的增强.因此,在提高硅材料发光效率方面,光子晶体微腔具有非常大的应用前景.     

SO2 emission characteristics and BP neural networks prediction in MSW/coal co-fired fluidized beds

The SO₂ emission characteristics of typical MSW components and their mixtures have been investigated in a Φ150mm fluidized bed. Some influencing factors of SO₂ emission in MSW fluidized bed incinerator were found out in this study. The SO₂ emission is increasing with the growth of the bed temperature, and it is rising with the increasing oxygen concentration at furnace exit. When the weight percentage of auxiliary coal is being raised, the conversion rate of S to SO₂ is largely going up. The SO₂ emission decreases if the desulfurizing agent (CaCO₃) is added during the incineration process, but the desulfurizing efficiency is weakened with the enhancement of the bed temperature. The fuel moisture content has a slight effect on the SO₂ emission. Based on these experimental results, a 12×6×1 three-layer BP neural networks prediction model of SO₂ emission in MSW/coal co-fired fluidized bed incinerator was built. The prediction results of this model give good agreement with the experimental results, which indicates that the model has relatively high accuracy and good generalization ability. It was found that BP neural network is an effectual method used to predict the SO₂ emission of MSW/coal co-fired fluidized bed incinerator.     

基于GWO-MLP的光伏系统输出功率短期预测模型

准确预测光伏系统的输出功率对微网系统的优化调度具有重要意义。为了减小光伏系统输出功率短期预测误差,文中采用多层感知器(Multi Layer Perceptron, MLP)神经网络作为主要的预测载体,将光照强度、温度、风速数据作为MLP的输入,光伏系统的输出功率作为MLP的输出,采用光伏电站的历史数据对MLP进行训练,并针对MLP在初始化权重和偏置量中存在的随机性问题,提出运用改进灰狼算法(Grey Wolf Optimizer, GWO)对MLP的初始权重和偏置量进行优化,减小MLP随机初始化的误差。仿真结果显示,文中提出的GWO-MLP在均方误差(Mean Square Error, MSE)、均方根误差(Root Mean Square Error, RMSE)、平均绝对误差(Mean Absolute Error, MAE)方面较MLP、Elman神经网络、支持向量机(Support Vector Machine, SVM)、极限学习机(Extreme Learning Machine, ELM)都有明显提高,表明所提方法可以准确预测光伏系统的输出功率。     

A model of wood flash pyrolysis in fluidized bed reactor

With a view of exploiting renewable biomass energy as a highly efficient and clean energy, liquid fuel from biomass pyrolysis, called bio-oil, is expected to play a major role in future energy supply. At present, fluidized bed technology appears to have maximum potential in producing high-quality bio-oil. A model of wood pyrolysis in a fluidized bed reactor has been developed. The effect of main operation parameters on wood pyrolysis product distribution was well simulated. The model shows that reaction temperature plays a major important role in wood pyrolysis. And a good agreement between experimental and theoretical results was obtained. It was shown that particles less than 500 μm could achieve a high heating-up rate to meet flash pyrolysis demand.     

一次风反切系统的数值模拟和多相流动特性分析

四角切圆燃烧锅炉,存在着稳燃和结渣的矛盾,一次风微反切技术已在多台锅炉上得到应用,较好地解决了这对矛盾并能在一定程度上降低ＮＯｘ的排放量。本文把湍流理论和多相流动理论应用于炉内空气动力场的计算机数值模拟,用投影法编制的计算软件对６００ＭＷ锅炉炉内流动进行了计算,得出了一次风反切系统中炉内速度场、实际切圆、颗粒运动轨迹等结果,与冷炉和冷模试验基本吻合,对一次风反切系统的设计和调试具有参考价值。     

国外大屏幕和平板显示的一些发展

电视技术的发展和人们视觉特性的要求,尤其是HDTV的出现,使图象显示正在向高清晰度、高亮度、大屏幕、平板化方向发展。各种各样的新型显示技术和产品正在加紧研制开发和推出,图象世界正在进入百花争妍的时代。本文拟就大屏幕和平板显示的一些国外发展情况作一介绍。     

基于SUPL状态机的AGPS终端的软件实现

抽象语法标记(ASN.1)广泛应用于数据通信领域.AGPS技术中的SUPL协议即采用了ASN.1中的压缩编码规则(PER)进行消息、数据的编解码.文章分析了SUPL协议中各种消息及数据的ASN.1描述和PER编码规则接口,并在此基础上介绍了一种基于PDA操作系统平台,以状态机为核心的SUPL协议客户端的软件实现.