基于卷积神经网络的OFDM-UWB信道环境识别

超宽带（UWB）无线通信技术被广泛应用于室内定位领域,其能识别出多径信道中的非视距信道,有助于去除影响信号的非理想因素,提升定位精度。基于OFDM方案的UWB系统,提出一种利用卷积神经网络对信道估计出的信道冲激响应时频图像进行训练,从而识别出信道环境的方法,将信道识别问题转化为图像识别问题,同时分析时频处理参数对识别结果的影响。仿真结果表明,该方法的识别率随通信系统比特信噪比（EbN0）的增加而提升,当EbN0增加至20 dB时稳定在90%,与传统基于支持向量机的信道识别方法相比获得了10%的性能提升。     

基于AODV协议的嵌入式自组织平台

无线通信的发展使得Ad-hoc的路由协议受到广泛关注,AODV协议是移动自组织网络中应用最广泛的按需路由协议,能有效的防止路由环路,适用于多种网络拓扑场景。同时,嵌入式开发在移动多媒体平台中起到重要作用,可实现专用、简单、高效的应用层服务平台。本文在基于Linux操作系统的嵌入式平台中搭建了AODV路由协议模块,实现了无线网卡rt3070.ko和自组织路由协议kaodv.ko的交叉编译和移植,验证了嵌入式平台下通过AODV无线路由协议进行组网的可行性和可靠性。通过对相关网络参数的分析,为Ad-Hoc的嵌入式多媒体应用提供了有益参考。     

基于身份感知模型的素描人脸识别方法

针对素描图像和光学图像之间存在较大的模态差异这一问题,提出了一种基于身份感知模型的素描人脸识别方法,实现跨模态图像生成和素描人脸识别。该方法应用新的感知损失来监督图像生成网络,生成更好的跨模态图像,减少模态差异带来的识别精度损失,并通过三元组损失来正则化类内和类间距离,增强识别模型的性能,用联合训练策略提升素描人脸识别能力。在UoM-SGFSv2、e-PRIP等素描人脸数据集上的实验结果表明,该方法识别效果优于其他对比算法。     

GNSS卫星信号模拟器码和载波NCO研究与实现

NCO是卫星信号模拟器中频信号处理的关键部分;介绍了GNSS卫星信号模拟器码NCO和载波NCO的原理及作用,建立DDS模型,确定基本参数并根据参数设计了码NCO和载波NCO基本结构;给出了码NCO和载波NCO的实现过程,利用verilog在Xilinx'ISE 11.2和modelsim6.5中完成载波NCO和码NCO的设计和仿真,在FPGA中进行了实现,并给出仿真波形和信号频谱图;本码NCO和载波NCO模块已应用于某型GNSS模拟器样机,通过程序仿真与样机测试,证明本码NCO和载波NCO模块性能满足GNSS卫星信号模拟器系统需求.     

一种抗震型横向剪切干涉仪的设计

针对机械扫描式光谱分析设备抗震、抗干扰能力差等问题,设计了抗震型横向剪切干涉系统,将分束镜作为机械扫描部分产生光程差,通过两个分束镜之间的连杆将引入的外部震动、干扰等相互抵消.计算了产生干涉条纹的干涉强度,分析了旋转分束镜对应角度的光程差函数,并求解了顺时针与逆时针对应的最大旋转角度.实验分别在3种条件下进行,采用850 nm激光器,对比此光学系统与传统迈克尔逊干涉仪的抗干扰能力,实验结果再与WQF530型光谱分析仪进行比较.实验结果显示:在防震平台上,两者的测试值都接近标准值;但当无防震设备时,系统的抗震设计可以有效抵消外部干扰造成的功率偏差及半宽增大,比传统迈克尔逊干涉仪测得的激光半宽精确提高一倍以上.     

基于IMU弹道测量的扩展卡尔曼滤波参数估计算法

针对目前弹道修正技术中测试参数误差较大且实时性和安全性不能满足相应的精度需求的现状,采用扩展混合卡尔曼滤波器来估计弹丸3种状态参数,包括弹丸在空气中的相对速度、高度和轨迹角.建立了卡尔曼滤波系统状态模型和以轴向加速度为观测量的量测模型.对IMU的测量数据进行滤波和估计处理,得到误差较小且满足实时性和安全性要求的弹道修正信息.仿真结果表明:滤波器在模拟数据下进行调节和测试,相对速度的估计性能良好.     

Adaptive detection with conic rejection to suppress deceptive jamming for frequency diverse MIMO radar

With traditional radar systems, it is not easy to classify and suppress the intended false targets, especially in case of the mainlobe deceptive jamming. In this paper, the deceptive jamming suppression issue is formulated as a problem of detecting the presence of target signal while rejecting potential deceptive jamming under the multiple-input multiple-output (MIMO) radar with frequency diverse array (FDA) as the transmit array. The problem at hand is settled by resorting to the generalized likelihood ratio test (GLRT); at the design stage we define the sets where the false target and true target lie in. Since FDA-MIMO radar provides controllable degrees of freedom in both range and angle domains, the sets are range–angle related. This implies that both range and angle properties can be used to suppress the false targets. Based on the detector, a two-pulse scheme is proposed to guarantee high rejection probability of deceptive jamming. At the analysis stage, the performance of the detector is assessed in comparison with the conventional MIMO scenario and other detectors. The performance assessment shows that the proposed solutions are effective in the presence of electronic countermeasure (ECM) systems, especially when facing mainlobe deceptive jamming.     

Electronic structure,carrier mobility and device properties for mixed-edge phagraphene nanoribbon by hetero-atom doping

Phagraphene, a new carbon allotrope, was proposed recently. We here select a mixed-edge phagraphene ribbon to study B-, N-, and BN-doping effects respectively on the geometric stability, electronic structure, carrier mobility, and device property. Calculations show that the energetic and thermal stability for these ribbons are very high. With different doping types and doping sites, the bandgap size of a ribbon may be nearly unchanged, increased, or decreased as compared with the intrinsic ribbon, and even become a metal, thus presenting fully tunable electronic structures. For this, the charge transfer shifting edge bands and the new formed hybridized bands due to doping play a crucial role. More interestingly, doping at different positions can regulate the carrier mobility of ribbon, and the difference of two orders of magnitude for hole mobility can be generated by BN-doping. In addition, the study on device property shows that there is a prominent negative differential resistance characteristics occurring in a BN-doped ribbon device. These findings are meaningful for understanding the doping effects on electronic properties of phagraphene nanoribbons.     

累积冲击作用下可恢复退化过程的可靠度评估

以对激光器进行可靠度评估为背景,在考虑累积冲击与自然退化同时引起产品失效的基础上,重点研究了冲击时间间隔对产品退化量的影响,建立了累积冲击作用下可恢复的退化模型。根据自然退化过程及泊松冲击更新理论,研究了累积冲击模型和累积冲击下的退化失效模型。引入条件分布,分析冲击时间间隔对退化量的影响,得出了累积泊松冲击下的可恢复退化失效模型。结合性能退化分析,给出了可恢复的退化过程的失效分布函数和可靠度函数。进行了激光器退化试验,结果表明:当激光器工作2 000h时,利用累积冲击下可恢复的退化失效模型评估得到的可靠度为0.53,与仿真结果相符,为利用累积冲击下退化失效模型评估得到的可靠度的2.79倍。结果验证了本文提出的利用可恢复的退化模型进行可靠度评估的合理性。     

常用冲击波压力传感器动态特性实验研究

针对冲击波测试传感器的宽带宽要求、现有传感器种类繁多的情况,文中对江苏联能、绵阳奇石缘、美国PCB和ENDEVCO公司生产的共7种用于冲击波超压测试的传感器进行了激波管动态标定实验,分析了放大器特性和安装误差对实验结果的影响,给出了各传感器的上升时间、超调量,用参数化的建模方法求出了各传感器的工作频带,实验结果表明8530B的超调量最小,上升时间最短,8530B和113A的工作频带比其他几种要高,大量程的113A也可用于小压力的测量。