基于深度神经网络的自适应波束形成算法

阵列天线接收到的期望信号和干扰信号,其入射的到达角度(Angle of Arrival,AOA)总是快速变化的,而传统波束形成算法计算量大,无法实时计算。针对这一问题,提出了一种基于深度神经网络的自适应波束形成(Deep Neural Network Adaptive Beamforming,DNNABF)算法,用入射信号AOA组成的向量作为网络输入,网络输出逼近最小方差无失真响应(Minimum Variance Distortionless Response,MVDR)算法求得的权矢量。仿真结果表明,卷积神经网络(Convolutional Neural Network,CNN)与DNNABF方法都能准确拟合MVDR算法权矢量,可在入射信号AOA快速变化时自适应地形成波束和零陷,但DNN计算速度相对MVDR有将近6.5倍的提升,训练模型时间也远低于CNN。     

优化EPON对本地P2P业务承载能力的研究

P2P流量已成为网络中的主要流量,但现有EPON系统不能很好的承载本地P2P业务.文中从MPCP协议的角度对逻辑链路标签及其过滤规则进行扩展,使本地P2P数据包不需经OLT端二层交换即可实现下行转发,从而大大改善了P2P业务的QoS.并以此方案为基础,提出改进EPON的DBA算法,设置专门的P2P时隙,实现P2P业务的全光域转发.两种方案的建模仿真结果表明,两者均能明显改善EPON对本地P2P业务的承载能力.     

A new SVM-based relevance feedback image retrieval using probabilistic feature and weighted kernel function

Relevance feedback (RF) is an effective approach to bridge the gap between low-level visual features and high-level semantic meanings in content-based image retrieval (CBIR). The support vector machine (SVM) based RF mechanisms have been used in different fields of image retrieval, but they often treat all positive and negative feedback samples equally, which will inevitably degrade the effectiveness of SVM-based RF approaches for CBIR. In fact, positive and negative feedback samples, different positive feedback samples, and different negative feedback samples all always have distinct properties. Moreover, each feedback interaction process is usually tedious and time-consuming because of complex visual features, so if too many times of iteration of feedback are asked, users may be impatient to interact with the CBIR system. To overcome the above limitations, we propose a new SVM-based RF approach using probabilistic feature and weighted kernel function in this paper. Firstly, the probabilistic features of each image are extracted by using principal components analysis (PCA) and the adapted Gaussian mixture models (AGMM) based dimension reduction, and the similarity is computed by employing Kullback–Leibler divergence. Secondly, the positive feedback samples and negative feedback samples are marked, and all feedback samples’ weight values are computed by utilizing the samples-based Relief feature weighting. Finally, the SVM kernel function is modified dynamically according to the feedback samples’ weight values. Extensive simulations on large databases show that the proposed algorithm is significantly more effective than the state-of-the-art approaches.     

Small-world brain functional network altered by watching 2D/3DTV

With the development of display technology, the healthy problems caused by watching 2D/3DTV have received more and more attention. This paper utilized resting-state functional magnetic resonance imaging to study the changes of small-world brain network before and after one-hour 2D/3DTV watching, and explored the brain fatigue mechanism caused by watching 2D/3DTV. We conclude that one-hour watching of 2DTV will not increase the burden of brain. On the contrary, one-hour watching of 3DTV requires the brain to regulate the efficiency of brain areas, such as temporal lobe and occipital lobe, which may explain the fact that watching 3DTV can easier cause brain fatigue than watching 2DTV.     

氮气流量对磁控溅射C掺杂TiO2薄膜光学性能的影响

采用磁控溅射法制备了C掺杂TiO₂薄膜,并研究了氮气引入溅射过程对薄膜光学性能的影响。利用X射线衍射仪、拉曼光谱仪、X射线光电子能谱仪、分光光度计和原子力显微镜分析了不同氮气流量下薄膜的微结构、元素价态、透光性能和表面形貌。结果表明,沉积的薄膜主要是非晶结构,拉曼光谱中存在少量锐钛矿相,且随着氮气流量增大,锐钛矿特征峰强度减弱,意味着晶粒出现细化。当氮气流量增大为4cm³/min时,C掺杂TiO₂薄膜内氮元素含量为3.54%,其光学带隙从3.29eV变化至3.55eV,可见光区的光学透过率明显提高。可见改变氮气流量可实现对C掺杂TiO₂薄膜光学带隙和光吸收率的有效调控。     

中速搜索引导长驻留采集的搜索调度方法

针对雷达信号侦察系统搜索时间长、截获概率低的问题,文中提出了一种基于空域宽开雷达信号侦察系统的搜索调度方法来优化设计驻留时间。根据驻留时间的长短,将驻留时间分为仅能截获单个雷达脉冲的中等驻留时间和可截获多个雷达脉冲的长驻留时间。搜索开始阶段使用较短的中等驻留时间用于频域的快速扫描,在截获信号后将驻留时间调整为长驻留时间,以便采集雷达信号用于频率及周期结构分析。仿真结果表明,提出的算法可合理利用系统资源,提高系统的截获性能,为现有雷达对抗侦察系统设计提供了有益参考。     

基于AVR的LED旋转屏设计

为了使显示屏的体积更小,成本更低,同时又能有较丰富的显示效果,采用AVR微处理器ATmegal6L作为核心控制芯片,由直流电机带动一列贴片LED旋转设计了圆柱形LED显示屏,可以由无线红外遥控装置随时切换显示的内容,可显示不同的文字、图案、系统时间等。利用少量发光二极管实现海量发光二极管才能实现的显示屏,同时该屏在旋转过程中显示,使得可视角更广,可以达到360°全方位。     

智能电网中D2D网络的通信资源管理优化方案

当前在智能电网的应用中,各种智能终端的使用,使得移动数据流量空前增长,电力互联方式在面临海量数据传输的需求时,由于资源受限,信道间会产生一定的干扰,从而影响通信质量.为了解决通信资源管理这一问题,与常见的移动边缘计算(MEC)方法不同,文中提出了一种网络资源分配方法,优化链路选择和子信道分配,以实现能量效率的最大化.仿...     

基于联锁的I／O控制器的设计与实现

随着城市轨道交通系统的发展,信号系统已经成为城市轨道交通运营管理的中枢神经。作为信号系统之一的联锁,其主要作用是建立进路、进路解锁、控制道岔以及信号机的开放。基于联锁的I／O控制器实现了联锁与现场设备的通信。通过控制器,联锁可以实时地接收现场设备的状态,又可以将控制命令发送到相应的设备,所以控制器的性能与安全对整个系统也起着决定性的作用。文中从硬件以及软件两方面,对主备控制器的设计进行了深入分析。该控制器具有较高的安全性,将是城市轨道交通的一个很好的发展方向。