Specific Emitter Identification Based on Visibility Graph Entropy

The specific emitter identification(SEI) technique determines the unique emitter of a given signal by using some external feature measurements of the signal. It has recently attracted a great deal of attention because many applications can benefit from it. This work addresses the SEI problem using two methods, namely, the normalized visibility graph entropy(NVGE) and the normalized horizontal visibility graph entropy(NHVGE)based on treating emitters as nonlinear dynamical systems. Firstly, the visibility graph(VG) and the horizontal visibility graph(HVG) are used to convert the instantaneous amplitude, phase and frequency of received signals into graphs. Then, based on the information captured by the VG and the HVG, the normalized Shannon entropy(NSE) calculated from the corresponding degree distributions are utilized as the rf fingerprint. Finally, four emitters from the same manufacturer are utilized to evaluate the performance of the two methods. Experimental results demonstrate that both the NHVGE-based method and NVGE-based method are quite effective and they perform much better than the method based on the normalized permutation entropy(NPE) in the case of a small amount of data. The NVGE-based method performs better than the NHVGE-based method since the VG can extract more information than the HVG does. Moreover, our methods do not distinguish between the transient signal and the steady-state signal, making it practical.     

基于AutoCAD平台的二次开发技术

AutoCAD软件是目前国内外使用的最为广泛的CAD软件,利用AutoCAD开发工具对其进行二次开发,可以满足不同用户的特殊要求.     

一种基于非完整二维相空间分量置换的混沌检测方法

由于混沌时间序列和随机过程具有很多类似的性质, 因而在实际中很难将两者区分开来. 混沌信号检测与识别是混沌时间序列分析中一个重要的课题. 混沌信号是由确定性的混沌映射或混沌系统产生的, 相比于高斯白噪声序列, 其在非完整的二维相空间中表现出更加丰富的结构特性. 本文通过研究混沌时间序列和高斯白噪声序列在非完整二维相空间中的分布特性, 利用混沌信号的非线性动力学特性, 提出了一种基于非完整二维相空间分量置换的混沌信号检测方法. 该方法首先由接收序列得到非完整的二维相空间, 基于第一维分量大小关系实现对第二维分量的置换与分组, 进一步求得F检验统计量. 然后利用混沌系统的局部特性, 获取非完整二维相空间的动力学结构信息, 实现对混沌序列的有效检测. 在高斯白噪声条件下对多种混沌信号进行了信号检测的数值仿真. 仿真结果表明: 相比置换熵检测, 本文所提算法所需数据量小、计算简单以及具有更低的时间复杂度, 同时对噪声具有更好的鲁棒性.     

利用正交试验法降低吨浆氯耗

针对沧州市造纸厂氯耗高的问题,我们曾在制漆工段做过试验,制定出合理的工艺条件,使漂液有效氯含量增大,氯气提取率有了明显的提高.但是漂白纸浆吨浆氯耗仍然偏高,距理想值尚有一些差距.根据我们化验的结果,漂白工段漂白纸浆残氯量较大,无疑造成了氯的损失。原因可能是加入漂液量过多或漂白闷浆时间太短所致,们可能二者兼而有之。因此我们试图探求漂白工段的工艺条件,寻找漂液用量、漂白时间和纸浆白度之间的关系。经分析决定用正交试验法。 一、试验考查指标:白度. 当纸浆强度指标符合要求时,白度越高越好,同时氯耗越少越好。 二、选因素 …