基于改进Henon映射和超混沌的双重语音加密算法

针对现有语音混沌加密算法密钥空间小、安全性差、加密效率低且无法实现密钥复杂度与加密效率的权衡等问题,提出了一种改进Henon映射和超混沌的双重语音加密算法。首先,为了使Henon映射具有更大的混沌空间和更高的混沌复杂度,通过扩展控制参数范围将非线性三角函数作为输入参数变量等手段对经典Henon映射进行了改进;其次,利用改进的Henon映射生成伪随机序列,并对语音数据进行单次不重复置乱加密,获得语音数据的初次加密结果;最后,利用Lorenz超混沌系统对初次加密后的语音数据进行Arnold二次置乱加密和异或扩散加密,获得最终的密文语音数据。实验结果表明,与现有方法相比该算法具有更大的密钥空间和更高的加密效率,且对各种密码攻击拥有更好的鲁棒性。     

基于主动-被动法对电光双稳态系统的混沌控制和同步研究

将主动-被动同步法改进后,用于对长延迟状态下电光双稳态系统进行混沌控制和同步研究,分别采用单向驱动方法和驱动-耦合方法研究电光双稳态系统的混沌控制和同步。数值模拟表明,在适当参数条件下应用单向驱动方法,驱动系统可以将响应系统控制到各周期状态,且驱动系统的状态决定了响应系统的状态;适当选取耦合系数和驱动强度,两种方案都可以实现驱动系统与响应系统之间的混沌同步。从同步效果上来看,驱动-耦合方法所需耦合系数更小,可控的耦合系数范围比较广,同步效果更好。     

单向耦合混沌同步系统的失真-频率特性

析了基于单向耦合混沌同步系统的失真－频率特性以及耦合系数与系统参数之 间的关系，导出了该系统幅频特性和相频特性的数学表达式，并就耦合系数的选取对系统频率特性 的影响问题进行了讨论。     

锁相环同步检波技术及在视频检波中的应用

早期电视机的视频检波均采用大信号包络检波电路,后来在集成化的电视机中,视频检波又都采用同步检波方式。虽然这种同步检波比大信号包络检波电路有明显的改进,但还是存在一些不足,不能做到真正的同步。针对上述不足,介绍一种先进的视频检波方式——锁相环同步检波,他可以克服上述的缺点,做到真正的同步。该检波方式在现代大屏幕彩色电视机的视频检波中取得很好的效果,并得到广泛应用。     

Synchronizing sequences and symbolic traversal techniques in test generation

Asynchronizing sequence drives a circuit from an arbitrary power-up state into a unique state. Test generation on a circuit without a reset state can be much simplified if the circuit has a synchronizing sequence. In this article, a framework and algorithms for test generation based on themultiple observation time strategy are developed by taking advantage of synchronizing sequences. Though it has been shown that the multiple observation time strategy can provide a higher fault coverage than the conventional single observation time strategy, until now the multiple observation time strategy has required a very complex tester operation model (referred asMultiple Observation time-Multiple Reference strategy (MOMR) in the sequel) over the conventional tester operation model. The overhead of MOMR, exponential in the worst case, has prevented widespread use of the method. However, when a circuit is synchronizable, test generation can employ the multiple observation time strategy and provide better fault coverages, without resorting to MOMR. This testing strategy is referred asMultiple Observation time-Single Reference strategy (MOSR). We prove in this article that the same fault coverage, that could be achieved in MOMR, can be obtained in MOSR, if the circuit under test generation is synchronizable. We investigate how a synchronizing sequences simplifies test generation and allows to use MOSR under multiple observation time strategy. The experimental results show that higher fault coverages and large savings in CPU time can be achieved by the proposed framework and algorithms over both existing single observation time strategy methods as well as other multiple observation time strategy methods.     

Double color image encryption based on fractional order discrete improved Henon map and Rubik’s cube transform

A double color image encryption method based on DNA (deoxyribonucleic acid) computation and chaos is proposed. Differently from the conventional algorithms, double color images are encrypted at the same time so that we can save information of each other, which makes the encryption more safe and reliable. In addition, a new chaotic fractional order (FO) discrete improved Henon map (FODIHM) is proposed as a pseudo-random number generator. To ensure the plain-image sensitivity of the encryption algorithm, the initial value of FODIHM is calculated from the hash value of the color image (SHA-256) and from the three additional keys entered by the user. Furthermore, a Rubik’s cube transform scrambles the pixels in each color component of the two images. Then, each pixel in each color component of the two images is diffused by means of different DNA coding rules. Finally, the CAT transform, based on FO discrete Logistic map and the classic XOR, is used to further improve the security performance. The key space size of the proposed algorithm is of order $10^{135}$, which is about 30 orders of magnitude higher than those available in the literature. The information entropies are 7.9974 and 7.9973, which are very close to the ideal entropy value of 8. The values of the unified average changing intensity (NPCI) are 99.630 and 99.623, while the number of pixels change rate (UACR) are 33.473 and 33.553, which are also close to the ideal NPCR and UACR value of 99.6094 and 33.4635, respectively. The numerical results and security analysis prove that the algorithm has good resistance to several classic attacks.     

Speech Denoising via Low‐Rank and Sparse Matrix Decomposition

In this letter, we propose an unsupervised framework for speech noise reduction based on the recent development of low‐rank and sparse matrix decomposition. The proposed framework directly separates the speech signal from noisy speech by decomposing the noisy speech spectrogram into three submatrices: the noise structure matrix, the clean speech structure matrix, and the residual noise matrix. Evaluations on the Noisex‐92 dataset show that the proposed method achieves a signal‐to‐distortion ratio approximately 2.48 dB and 3.23 dB higher than that of the robust principal component analysis method and the non‐negative matrix factorization method, respectively, when the input SNR is ?5 dB.     

改进混沌方程及其在保密VoIP系统中的应用与实现

传统二维Henon混沌映射由于复杂度低、混沌区间小,在应用于加密算法时存在安全隐患。针对这一问题提出了一种改进型Henon映射,相较传统映射混沌区间提升了82.35%,复杂度提升了60.8%,更加适用于混沌保密通信系统的设计。在ARM平台上,基于改进型Henon映射设计实现了一种保密通信系统。其中,加密端由音频编解码芯片产生明文数字话音信号,主控芯片使用二值混沌序列对其进行流密码加密,并通过以太网芯片完成密文话音在IP网的传输,解密端在帧同步后通过逆过程实现话音回放。实现结果表明,在计算精度范围内系统对密钥敏感性强,加密前后话音信号统计相关特性低于0.3,保密效果较好。     

Beyond Solid Solution High-Entropy Alloys: Tailoring Magnetic Properties via Spinodal Decomposition

Since its first emergence in 2004, the high-entropy alloy (HEA) concept has aimed at stabilizing single- or dual-phase multi-element solid solutions through high mixing entropy. Here, this strategy is changed and renders such massive solid solutions metastable, to trigger spinodal decomposition for improving the alloys’ magnetic properties. The motivation for starting from a HEA for this approach is to provide the chemical degrees of freedom required to tailor spinodal behavior using multiple components. The key idea is to form Fe-Co enriched regions which have an expanded volume (relative to unconstrained Fe-Co), due to coherency constraints imposed by the surrounding HEA matrix. As demonstrated by theory and experiments, this leads to improved magnetic properties of the decomposed alloy relative to the original solid solution matrix. In a prototype magnetic FeCoNiMnCu HEA, it is shown that the modulated structures, achieved by spinodal decomposition, lead to an increase of the Curie temperature by 48% and a simultaneous increase of magnetization by 70% at ambient temperature as compared to the homogenized single-phase reference alloy. The findings thus open a pathway for the development of advanced functional HEAs.     

自适应掩膜信号集成局部特征尺度分解及其应用

局部特征尺度分解（LCD）是为克服经验模态分解（EMD）中均值曲线构造的不足而提出的一种自适应信号分解方法,已被应用于机械故障诊断领域.但LCD存在与EMD类似的模态混叠问题,为此,基于均匀相位差掩膜信号构造,提出了自适应掩膜信号集成局部特征尺度分解（AMSELCD）,该方法不仅能够将一个复杂信号自适应地分解为若干个本征模态函数和一个剩余项之和,而且能够有效地解决LCD的模态混叠现象.通过仿真信号分析,将AMSELCD与现有多种抑制模态分解方法进行了对比,结果表明了所提方法的有效性和优越性.最后,针对滚动轴承和转子碰摩故障振动信号的调制特征,将所提AMSELCD方法应用于转子碰摩和滚动轴承的故障诊断,对比和实验分析结果进一步验证了所提方法的有效性和优越性.     

SDH的映射和同步复用原理（一）

同步复用和映射方法是ＳＤＨ最具特色的内容。本文在简要介绍ＳＤＨ基本知识的基础上，通过对由１４０Ｍｂｉｔ／ｓ信号、２Ｍｂｉｔ／ｓ信号组成ＳＴＭ－１信号的介绍，可使读者对ＳＤＨ有进一步的了解。