基于排列熵和CHMM的齿轮故障诊断

针对齿轮故障特征提取和状态识别困难的问题,提出一种基于排列熵和连续隐马尔可夫模型(CHMM)的齿轮故障诊断方法。首先对提取的目标齿轮啮合信号作降噪处理,再采用排列熵算法进行分析,提取排列熵均值、方均根、最大值、最小值作为特征量输入到CHMM中训练和识别,通过对比最大对数似然概率值来确定齿轮的故障。最后在变速箱齿轮故障模拟试验台上,对正常、轻微磨损、严重磨损和断齿4种齿轮状态进行试验验证,结果表明该方法能有效地对齿轮故障进行诊断。     

基于多尺度排列熵的铣削颤振在线监测方法

排列熵是系统复杂性和规则性的一种测度,具有概念简单、稳健和计算速度快等优点。考虑到单尺度排列熵在反映铣削力信号特征方面的不足,通过试验分析提出基于单尺度排列熵和尺度4排列熵作指标的铣削颤振在线检测方法。通过试验验证,所提出的方法能有效地检测铣削颤振。同时基于多尺度排列熵的方法对于铣削力信号采集过程中的噪声、工艺参数变化等不敏感,因此这种方法适用于实际工业生产中的在线铣削颤振监测。     

气-固流化床压力脉动信号的多尺度排列熵分析

采用多尺度排列熵算法对气-固流化床内4种流型的压力脉动信号进行研究,结果表明:不同流型由于其动力学特性不同,导致压力脉动信号的多尺度排列熵值存在差异——4种流花形态的排列熵值都是随着尺度的增加而增大,其中固定床在大尺度上熵值最大,气力输送床在小尺度上熵值最大,鼓泡流化床在所有尺度上熵值最小;此外,多尺度排列熵值变化速率特征是流型辨识的新指示器。     

LTE turbo 解码器设计

本文提出一种可以用于lte小基站的turbo码解码器设计, 它支持LTE标准中的188种不同长度的TURBO码解码。设计采用了最多16路的并行解码,迭代次数可设定。解码器提采用了一种改进的软输入软输出设计。设计采用了轮流计算前向状态矩阵,和后项状态矩阵。这样可以缩短基二算法的关键路径,同时分支传输概率也可以直接用于计算不再需要保存。分组数据利用列地址映射,和行数据交换完成整个码的交织计算,利用相反的过程完成解交织计算。每个时钟都可以产生交织与解交织数据,用于解码和存储运算。     

基于排列熵的电磁声发射信号到达时间识别

排列熵算法简单高效,能够反映出信号的微小变化,是一种有效的信号突变检测工具。通过引入信号包络排列熵分析方法,对声发射信号到达时间识别问题进行求解。排列熵对信号幅值的大小不敏感,但对信号幅值的变化敏感,通过记录信号包络排列熵的变化,根据包络排列熵第一个极小值时刻来识别信号到达时间。根据裂纹电磁声发射实测信号识别结果可知,包络排列熵方法对声发射信号到达时间具有较高的识别精度。     

A new image encryption algorithm based on non-adjacent coupled map lattices

We propose a new image encryption algorithm which is based on the spatiotemporal non-adjacent coupled map lattices. The system of non-adjacent coupled map lattices has more outstanding cryptography features in dynamics than the logistic map or coupled map lattices does. In the proposed image encryption, we employ a bit-level pixel permutation strategy which enables bit planes of pixels permute mutually without any extra storage space. Simulations have been carried out and the results demonstrate the superior security and high efficiency of the proposed algorithm.     

Rejewski’s equations: Solving for the entry permutation

In 1932, Marian Rejewski, who was a young mathematician working at the Polish Cipher Bureau, brilliantly recovered the internal wiring of the military Enigma. His initial efforts were unsuccessful because he assumed that the entry permutation was the same as in the commercial machine. Luckily he tried the identity permutation as an alternative and that proved to be correct. This note describes how Rejewski’s equations may be used to deduce the entry permutation without any guesswork, a technique that was later rediscovered by Alan Turing and by Lieutenant Andrew Gleason.     

Multi-objective adaptive large neighborhood search for distributed reentrant permutation flow shop scheduling

Factory management plays an important role in improving the productivity and quality of service in the production process. In particular, the distributed permutation flow shop scheduling problem with multiple factories is considered a priority factor in the factory automation. This study proposes a novel model of the developed distributed scheduling by supplementing the reentrant characteristic into the model of distributed reentrant permutation flow shop (DRPFS) scheduling. This problem is described as a given set of jobs with a number of reentrant layers is processed in the factories, which compromises a set of machines, with the same properties. The aim of the study is to determine the number of factory needs to be used, jobs assignment to certain factory and sequence of job assigned to the factory in order to simultaneously satisfy three objectives of minimizing makespan, total cost and average tardiness. To do this, a novel multi-objective adaptive large neighborhood search (MOALNS) algorithm is developed for finding the near optimal solutions based on the Pareto front. Various destroy and repair operators are presented to balance between intensification and diversification of searching process. The numerical examples of computational experiments are carried out to validate the proposed model. The analytical results on the performance of proposed algorithm are checked and compared with the existing methods to validate the effectiveness and robustness of the proposed potential algorithm in handling the DRPFS problem.     

A RAPID YES-NO COMPUTER-AIDED COMMUNICATOR

Abstract

When attacking the German Enigma cipher machine during the 1930s, the Polish mathematician Marian Rejewski developed a catalog of disjoint cycles of permutations generated by Enigma indicators. By comparing patterns that resulted from message indicators with his catalog, Rejewski was able to determine the ground settings. Well, not quite—the mapping from the disjoint cycles to the ground settings is not one-to-one. Rejewski's catalog no longer exists. This article reports on the output of a program that “recreates” the catalog and answers the question “How far from being one-to-one is the mapping?”     

针对RFID身份认证协议——ARAP协议的攻击及改进

证明了针对匿名RFID身份认证协议ARAP协议可以进行假冒伪造攻击,并提出了改进版的ARAP协议。攻击的实质在于协议中运用的异或运算会将相同的值消去,或者可以设计特定的随机数实现重放攻击。提出了一种新的运算操作———置换操作,并在改进版的ARAP协议中将原协议的部分异或运算改为置换操作。改进版的ARAP协议还能抵抗跟踪攻击、非同步攻击和重放攻击等。