CaGd2(MoO4)4:Sm3+,La3+荧光粉的 制备及发光性能研究

采用高温固相法合成了CaGd2-x(MoO4)4:xSm3+(x=0.1、0.3、0.5、0.7、0.9)橙红色荧光粉.研究了样品的X射线衍射谱(XRD)、激发光谱和发射光谱.从XRD图谱测试结果表明,在900℃下烧结6 h后得到的样品为纯CaMnO4晶相,样品CaGd2(MoO4)4:Sm3+的激发光谱由两部分组成:一部分(250～340)nm为属于O2--M6+O的电荷迁移带;另一部分(350～450)nm的系列线状峰是Sm3+的f-f跃迁特征激发峰.样品在405 nm(6H5/24F7/2)下激发得到的发射光谱,其主发射峰位于646 nm(6 G5/26 H7/2)处.当Sm3+掺杂浓度高于2;时,样品CaGd2-x(MoO4)4:xSm3+发生浓度猝灭现象,该现象是由于离子间的能量传递.在CaGd1.5(MoO4)4:0.5Sm3+样品中掺入一定浓度La3+,掺入La3+并没有改变CaGd2(MoO4)4:Sm3+光谱峰的形状和位置,当y=0.8时,荧光粉的发光强度最好.通过测量计算GIE在405 nm激发下的色坐标,显示色坐标均在橙红色区域移动,表明荧光粉的光色性较好.     

基于高阻硅的毫米波IPD 滤波器研究

5G 通信迫切需要毫米波集成无源器件(Integrated Passive Device,IPD),要求该类器件低成本、高性能。基于高阻硅(High Resistivity Silicon, HRS)工艺设计并加工了一款四阶交叉耦合毫米波微带滤波器,基于测试结果和有耗耦合矩阵理论反提取得到四阶滤波器谐振器的真实无载品质因素。进而对高阻硅基的毫米波工艺参数(例如,损耗角正切)进行修正,利用电磁仿真软件进行验证;分析了金属粗糙度对于滤波器损耗的影响。修正后的模型仿真结果和测试结果吻合较好,验证了修正后毫米波段高阻硅基参数的有效性,为芯片级毫米波无源器件的设计提供了支撑。     

基于轻量型卷积神经网络的图像识别

针对卷积神经网络参数数量多并且分类精度不高的问题,提出了基于轻量型的卷积神经网络模型.该模型是把上层输出先通过数量较少的卷积核,再通过并行操作得到与原模型相同维度的输出.并行处理时,通过不同的卷积核大小增加特征的多样性,最后采用级联或融合的方式把并行输出整合在一起.和同规模的模型相比,该模型在减少参数的同时增加了网络的深度.在实验阶段用该网络在caltech256和I01 food数据集上进行测试,实验结果表明该模型性能更优.     

频率漂移的RFID冲突标签的物理层恢复

在无线射频识别（RFID）系统中,物理层上恢复冲突标签可有效提高系统识别效率.然而在超高频（UHF） RFID系统中,频率漂移是一普遍现象,它对物理层的冲突标签恢复有一定的影响.本文针对频率漂移的标签冲突恢复问题,采用径向基函数（RBF）网络分离算法对冲突信号分离,并利用FM0电平边沿跳变的原理实现解码,以此实现冲突标签信号恢复.实验结果表明,当发生频率漂移时,本文的方法在误码率和分离效率上均优于传统算法.     

Nondata-aided error vector magnitude performance analysis over κ−μ shadowed fading channel

The performance prediction of wireless system over κ?μ shadowed fading channels was a challenging problem of wireless communications,which affects transmission scheme design seriously.To solve this problem,a novel method of quantifying the κ?μ shadowed fading channels performance based on nondata-aided error vector magnitude (NDA-EVM) was proposed.NDA-EVM was considered as a new metric to evaluate the change of the channels.The unified model to calculate different modulation order of NDA-EVM was analytically derived by maximum likelihood criterion.Moreover,the relationship between the κ?μ distribution and the NDA-EVM was built by using the attenuation factor of the channel as intermediate variable.Thereafter,the lower bounds of the NDA-EVM over the κ?μ shadowed fading channels were formulated,which was also simplified for various typical channels.The theoretical analysis was taken,moreover,numerical results were also conducted to verify the effectiveness of the derived formulation.It shows that NDA-EVM estimation has the lest root mean square error than data-aided signal to noise ratio (DA-SNR) estimation and error vector magnitude (DA-EVM) estimation over the κ?μ shadowed fading channels.The derived lower bounds closely match the theoretical values,especially at low SNR.In addition,the lower bounds are negatively related to all of the parameters of the κ?μ shadowed fading channels,which make it sensitive to the change of the fading channels.     

超长线列红外探测器杜瓦真空寿命评估方法

针对超长线列红外探测器杜瓦具有容积大、零部件种类多、材料放气源多,特别是集成式超长线列杜瓦与内充3 MPa高压氦气的直线脉管冷指封装集成等特点,基于材料解析放气及渗透理论,建立了超长线列杜瓦组件真空寿命评估模型,对分置式与集成式超长线列杜瓦的真空寿命进行了计算,其真空寿命预计值均可以达到2年。设计了一种杜瓦真空度在线监测结构对这两类杜瓦的真空度进行了实时监测,分置式及集成式杜瓦真空寿命预计值与实测值相对误差分别为5.8%和6.96%。因集成式杜瓦真空寿命估算较为困难,对其热负载通过制冷性能进行实验验证,其热负载2年后未发生明显变化。     

New method of text representation model based on neural network

Method of text representation model was proposed to extract word-embedding from text feature.Firstly,the word-embedding of the dual word-embedding list based on dictionary index and the corresponding part of speech index was created.Then,feature vectors was obtained further from these extracted word-embeddings by using Bi-LSTM recurrent neural network.Finally,the sentence vectors were processed by mean-pooling layer and text categorization was classified by softmax layer.The training effects and extraction performance of the combination model of Bi-LSTM and double word-embedding neural network were verified.The experimental results show that this model not only performs well in dealing with the high-quality text feature vector and the expression sequence,but also significantly outperforms other three kinds of neural networks,which includes LSTM,LSTM+context window and Bi-LSTM.     

Improved LEACH protocol algorithm for WSN based on energy balance and high efficiency

The improved energy-saving algorithm for the energy efficient and balanced protocol (LEACH-improved) was proposed.In the algorithm,the residual energy factor,the distance factor and the node density factor was added to improve the threshold formula.Moreover,in the various application scenarios of WSN,based on the different effects on the selection of cluster heads caused by the residual energy and geographical location,the weighting factor was introduced.Results of simulation experiments show that the improved algorithm can effectively reduce the network energy consumption and prolong the network lifetime.     

分布式反馈激光器调制特性研究

为了深入了解分布式反馈激光器（DFB）的发光机理与调制特性,通过理论分析和实验对DFB的调谐特性进行了研究。得到FITEL和JDS Uniphase两款激光器调制电流与输出中心波长的对应关系和两种确定系数不同的拟合方程,证明了这两款DFB激光器在实际应用中存在非线性关系。结果表明,FITELFRL15DCWD-A82激光器的3dB带宽与驱动电流幅值关系为3.715pm/mA;该调制结果优化了该激光器的可用相干长度,并验证了驱动信号频率变化不影响3dB光谱宽度。对DFB激光器低频调制特性的定量分析结果可为相干检测系统驱动电路设计提供实验依据。     

基于RMAP_IP核的PCIe-SpaceWire接口卡的研究与实现

针对SpaceWire数据通信的特点,提出一种实现SpaceWire接口卡的方法.通过对SpaceWire总线技术和PCIe总线技术的研究,提出以RMAP_ IP核为基础,利用PCIe实现SpaceWire节点设备与星载主机的通信.重点介绍了SpaceWire接口卡硬件设计的方案,同时自主研制了驱动程序与应用程序对该方法进行了验证.实验表明:该接口卡具有设计简单、尺寸小、应用范围广,以及低功耗等特点,可以实现SpaceWire设备和上位机进行通信的功能,并可用来对SpaceWire网络通信状况进行实时监测.