scholarly journals Chaotic Time-Delay Signature Suppression and Entropy Growth Enhancement Using Frequency-Band Extractor

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 516
Author(s):  
Yanqiang Guo ◽  
Tong Liu ◽  
Tong Zhao ◽  
Haojie Zhang ◽  
Xiaomin Guo
Keyword(s):  
Time Delay ◽  
Frequency Band ◽  
Secure Communication ◽  
Optical Feedback ◽  
Random Number Generation ◽  
Permutation Entropy ◽  
Growth Enhancement ◽  
Dynamical Process ◽  
Promising Tool ◽  
Entropy Growth

By frequency-band extracting, we experimentally and theoretically investigate time-delay signature (TDS) suppression and entropy growth enhancement of a chaotic optical-feedback semiconductor laser under different injection currents and feedback strengths. The TDS and entropy growth are quantified by the peak value of autocorrelation function and the difference of permutation entropy at the feedback delay time. At the optimal extracting bandwidth, the measured TDS is suppressed up to 96% compared to the original chaos, and the entropy growth is higher than the noise-dominated threshold, indicating that the dynamical process is noisy. The effects of extracting bandwidth and radio frequencies on the TDS and entropy growth are also clarified experimentally and theoretically. The experimental results are in good agreements with the theoretical results. The skewness of the laser intensity distribution is effectively improved to 0.001 with the optimal extracting bandwidth. This technique provides a promising tool to extract randomness and prepare desired entropy sources for chaotic secure communication and random number generation.

scholarly journals Time-Delay Robust Nonlinear Dynamic Inversion for Chaos Synchronization with Application to Secure Communications

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Eunro Kim ◽  
Inseok Yang ◽  
Dongik Lee
Keyword(s):  
Time Delay ◽  
Nonlinear Dynamic ◽  
Secure Communication ◽  
Chaos Synchronization ◽  
Chaotic Behavior ◽  
Control Technique ◽  
Delay Systems ◽  
Dynamic Inversion ◽  
Synchronization Problem ◽  
Nonlinear Dynamic Inversion

The time-delay robust nonlinear dynamic inversion (TDRNDI) control technique is proposed to synchronize time-delay Chen systems. The time-delay Chen circuit is simple but exhibits complex irregular (chaotic) behavior. For this reason, this circuit can be efficiently used to encrypt messages for secure communication. In this paper, the nonlinear control-based chaos synchronization problem is considered. The proposed TDRNDI controller is a modified version of a robust nonlinear dynamic inversion (RNDI) applicable to chaotic systems, including time-delay systems. The performance and feasibility of the proposed TDRNDI controller are demonstrated by conducting numerical simulations with application to a secure communication network.

The Role of Master Laser with Feedback in Time-Delay Signature Suppression of Semiconductor Laser Subject to Chaotic Optical Injection

2017 ◽  
Vol 27 (11) ◽  
pp. 1750169 ◽  
Author(s):  
Liyue Zhang ◽  
Wei Pan ◽  
Penghua Mu ◽  
Xiaofeng Li ◽  
Shuiying Xiang ◽  
...  
Keyword(s):  
Time Delay ◽  
Semiconductor Laser ◽  
Optical Feedback ◽  
Bias Current ◽  
Optical Injection ◽  
Strength Parameter ◽  
Master Laser ◽  
Feedback Strength ◽  
Chaotic Signals

The important role of parameters in master laser with optical feedback for the elimination of time-delay (TD) signature in semiconductor laser subject to chaotic optical injection is investigated systemically. The experimental results show that TD signature suppressed chaotic signals can be credibly generated by increasing the feedback strength of the master laser, which is quite different from the trends observed in semiconductor laser (SL) with optical feedback. Systematically numerical analysis is also carried out as a validation, and it is shown that with low bias current and strong feedback strength, parameter regions contributing to successful TD suppression are much wider. Furthermore, it is shown that the influence of frequency detuning in TD concealment will change with the increase of feedback strength. All the numerical results are in perfect accordance with experimental observation.

scholarly journals Time-Frequency Analysis and Application of a Vibration Signal of Tunnel Excavation Blasting Based on CEEMD-MPE-HT

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Chen-yang Ma ◽  
Li Wu ◽  
Miao Sun ◽  
Qing Yuan
Keyword(s):  
Empirical Mode Decomposition ◽  
Frequency Band ◽  
Frequency Analysis ◽  
Frequency Characteristic ◽  
Permutation Entropy ◽  
Natural Vibration Frequency ◽  
Characteristic Parameters ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Mode Decomposition

The traditional empirical mode decomposition method cannot accurately extract the time-frequency characteristic parameters contained in the noisy seismic monitoring signals. In this paper, the time-frequency analysis model of CEEMD-MPE-HT is established by introducing the multiscale permutation entropy (MPE), combining with the optimized empirical mode decomposition (CEEMD) and Hilbert transform (HT). The accuracy of the model is verified by the simulation signal mixed with noise. Based on the project of Loushan two-to-four in situ expansion tunnel, a CEEMD-MPE-HT model is used to extract and analyze the time-frequency characteristic parameters of blasting seismic signals. The results show that the energy of the seismic wave signal is mainly concentrated in the frequency band above 100 Hz, while the natural vibration frequency of the adjacent existing tunnel is far less than this frequency band, and the excavation blasting of the tunnel will not cause the resonance of the adjacent existing tunnel.

Time-Delay Signature Suppression in Chaotic Laser Source with Optical Feedback by Brillouin Scattering

2017 ◽  
Vol 44 (2) ◽  
pp. 0208002
Author(s):  
张建忠 Zhang Jianzhong ◽  
冯昌坤 Feng Changkun ◽  
张明江 Zhang Mingjiang ◽  
刘 毅 Liu Yi ◽  
张永宁 Zhang Yongning
Keyword(s):  
Time Delay ◽  
Optical Feedback ◽  
Brillouin Scattering ◽  
Laser Source ◽  
Chaotic Laser

Time-delay signature concealment of polarizationresolved chaos outputs in vertical-cavity surface-emitting lasers with variablepolarization filtered optical feedback

2015 ◽  
Vol 13 (9) ◽  
pp. 091401-91405
Author(s):  
Li Zhou Li Zhou ◽  
Guangqiong Xia Guangqiong Xia ◽  
Zhuqiang Zhong Zhuqiang Zhong ◽  
Jiagui Wu Jiagui Wu ◽  
Shuntian Wang Shuntian Wang ◽  
...  
Keyword(s):  
Time Delay ◽  
Optical Feedback ◽  
Cavity Surface ◽  
Surface Emitting Lasers ◽  
Vertical Cavity Surface ◽  
Emitting Lasers ◽  
Vertical Cavity

Generalized Hybrid Dislocated Function Projective Synchronization of Chaotic Systems with Time Delay

2014 ◽  
Vol 574 ◽  
pp. 672-678 ◽  
Author(s):  
Rui Li ◽  
Guang Jun Zhang ◽  
Tao Zhu ◽  
Xu Jing Wang ◽  
Jun Dong
Keyword(s):  
Time Delay ◽  
Secure Communication ◽  
Chaotic Systems ◽  
Control Method ◽  
Scaling Factor ◽  
Projective Synchronization ◽  
Feedback Gain ◽  
Uncertain Parameters ◽  
Function Projective Synchronization ◽  
Feedback Control Method

In order to improve the security of secure communication, a novel generalized hybrid dislocated function projective synchronization (GHDFPS) was proposed and GHDFPS of time delay chaotic systems with uncertain parameters were researched in this paper. Due to time delay, the chaotic system can produce multiple positive Lyapunov exponential; this characteristic can enhance security in secure communications noticeably. Based on Lyapunove stability theory and modified hybrid feedback control method, the modified hybrid feedback controller and the parameter updating laws were designed for the GHDFPS between the two time delay chaotic systems with uncertain parameters. The feedback gain can be adjusted automatically according to the synchronization error values. Under the controller, generalized hybrid dislocated function projective synchronization of the two chaotic systems is achieved, and the uncertain parameters of response systems are identified. The chaotic item is added in the function scale factor. The chaotic item in the function scaling factor makes function scaling factor more complex and unpredictable. So this can enhance the features of indeterminism in secure communication. The time delay feedback Lorenz system as an example; by numerical simulations the effectiveness of the proposed method is demonstrated.

scholarly journals The Optimized Multi-Scale Permutation Entropy and Its Application in Compound Fault Diagnosis of Rotating Machinery

Entropy ◽  
2019 ◽  
Vol 21 (2) ◽  
pp. 170 ◽  
Author(s):  
Xianzhi Wang ◽  
Shubin Si ◽  
Yu Wei ◽  
Yongbo Li
Keyword(s):  
Time Delay ◽  
Parameter Selection ◽  
Permutation Entropy ◽  
Embedding Dimension ◽  
Optimization Strategy ◽  
Extraction Ability ◽  
Dynamic Changes ◽  
Multi Scale ◽  
Simulated Signal ◽  
Selection Of

Multi-scale permutation entropy (MPE) is a statistic indicator to detect nonlinear dynamic changes in time series, which has merits of high calculation efficiency, good robust ability, and independence from prior knowledge, etc. However, the performance of MPE is dependent on the parameter selection of embedding dimension and time delay. To complete the automatic parameter selection of MPE, a novel parameter optimization strategy of MPE is proposed, namely optimized multi-scale permutation entropy (OMPE). In the OMPE method, an improved Cao method is proposed to adaptively select the embedding dimension. Meanwhile, the time delay is determined based on mutual information. To verify the effectiveness of OMPE method, a simulated signal and two experimental signals are used for validation. Results demonstrate that the proposed OMPE method has a better feature extraction ability comparing with existing MPE methods.

scholarly journals Time delay signature concealment of optical feedback induced chaos in an external cavity semiconductor laser

2010 ◽  
Vol 18 (7) ◽  
pp. 6661 ◽  
Author(s):  
Jia-Gui Wu ◽  
Guang-Qiong Xia ◽  
Xi Tang ◽  
Xiao-Dong Lin ◽  
Tao Deng ◽  
...  
Keyword(s):  
Time Delay ◽  
Semiconductor Laser ◽  
Optical Feedback ◽  
External Cavity

scholarly journals Time-Delay Identification in a Chaotic Semiconductor Laser With Optical Feedback: A Dynamical Point of View

2009 ◽  
Vol 45 (7) ◽  
pp. 879-1891 ◽  
Author(s):  
Damien Rontani ◽  
Alexandre Locquet ◽  
Marc Sciamanna ◽  
David S. Citrin ◽  
Silvia Ortin
Keyword(s):  
Time Delay ◽  
Semiconductor Laser ◽  
Optical Feedback ◽  
Point Of View
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