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The traditional image encryption algorithms based on low-dimensional chaotic systems often have the problems on small key space and poor security. Aiming at these problems, firstly, this paper proposed a new class of four-dimensional discrete chaotic systems with unstable equilibrium points. Then it used numerical simulation method to analyze the dynamic behavior of the systems, and the number of positive Lyapunov exponents reached three. Then based on the new chaotic systems, this paper designed a new image encryption scheme. Furthermore, It analyzed the security of the algorithm scheme through the distribution histogram, correlation coefficient, information entropy and the sensitivity of this encryption scheme to the parameters. The results show that the encryption scheme has strong resistance to external attack, has a key space up to 2996 and is highly secure. [ABSTRACT FROM AUTHOR]

Perturbation of chaotic system can effectively solve the degradation of chaotic system dynamic characteristics caused by computer finite precision effect. This paper proposed parameter perturbation scheme for digital chaotic system based on the construction method of Cantor set in interval mapping. This scheme spread the sequence values obtained from each iteration of chaotic system proportionally to the compressed interval of chaotic state parameters, so as to achieve the purpose of disturbing chaotic sequence. The experimental simulation and analysis show that the chaotic system with disturbance has better chaotic characteristics, larger parameter range and higher complexity. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Image & Graphics is the property of Editorial Office of Journal of Image & Graphics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Application Research of Computers / Jisuanji Yingyong Yanjiu is the property of Application Research of Computers Edition and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The standard whale optimization algorithm( WOA ) and some derivative algorithms are studied and experimented to solve the problem of poor results of some examples. It is proved that there is a zero searching preference trap in the " encircling" process of WOA. In addition, the unbalanced search characteristics of chaos optimization algorithm( COA) make it difficult to reconcile the chaos initial population and swarm intelligence optimization process. In order to improve the above defects, this paper selected two chaotic systems and bubble net hunting strategy, and designed a set of fusion optimization algorithm. The algorithm adopted the baseline adaptive oscillation group partition strategy based on fitness to guide the group behavior pattern, gave full play to the role of chaotic system, and balanced the exploration and convergence performance. It used the new algorithm to solve the general/improved examples and engineering application cases. It 's obviously that the performance of the algorithm is better than the contrast group algorithm,and there is no searching preference. [ABSTRACT FROM AUTHOR]

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Chongqing University of Posts & Telecommunications (Natural Science Edition) is the property of Chongqing University of Posts & Telecommunications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to overcome the degration of chaotic and improve the randomness of the sequence, this paper proposed a new method of generating pseudo-random numbers based on logistic chaotic mapping. It used four one-dimensional logistic cha¬otic maps. Each iteration randomly selected one to perturb the other three logistic maps, adding variable parameters and ran¬domly grouping them dynamically to improve the randomness of the sequences. Meanwhile, it enlarged the period of sequence and avoided recurrence of sequences. The pseudo-random number generator is easy to implement by software. The sequence can pass the NIST SP8(X)-22 randomness test. It has good randomness and can apply in the field of information security such as secure communication. [ABSTRACT FROM AUTHOR]

Compressive sensing is a new sampling theory which makes use of the sparsity of signals to recover the high-dimension signal from very few measurements. Unfortunately,most of the existing measurement matrices have high correlation between elements,which can not guarantee exact recovery and has greatly restricted their application prospects. Based on this,this paper proposed a novel Chebyshev chaotic measurement sensing matrix based on sampling columnization( SC3M). The sampling columnization and normalization guaranteed the low correlation in column of SC3 M,which optimized the recovery effect. Moreover,it proved that the proposed SC3 M sensing matrix satisfies the RIP with overwhelming probability from the Johnson-Lindenstrauss lemma. Numerical simulations show that the SC3 M is sufficient to guarantee exact recovery,which shows better effect compared to other popular measurement matrixes such as the fully random matrix,Bernoulli matrix and Gaussian sensing matrix. [ABSTRACT FROM AUTHOR]

Considering the nonlinear and uncertainty of magnetic powder brake( MPB) torque loading system,this paper pre­sented a new fuzzy neural network (FNN) PID controller based on chaotic artificial fish swarm algorithm( CAFSA). The con­troller used a fuzzy neural network based on Mamdani model to adjust the control parameters of PID controllers. It also com­bined offline chaotic artificial fish swarm algorithm and online BP algorithm to learn and adjust the parameters of fuzzy neural network. Using MATLAB for offline simulation and optimization, then did experiments using the PID controller, FNN control­ler, AFSA-FNN controller and the designed controller. The experimental results show that this controller is more stability, fas­ter and more effective. It can solve the lag problem of the MPB torque loading system. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central China Normal University is the property of Huazhong Normal University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the stability theorem of the fractional nonlinear system with time-delay, the stability control of fractional chaotic system with time-delay can be realized by linear feedback controller design. Based on the method of the matrix configuration controller design, the synchronization of fractional chaotic system with unknown parameters can be realized by using the method of delay separation. This paper took fractional complex Lorenz system with time-delay as an example, seperated the real pail and imaginary part of each variable of original system to study their chaotic characteristics and chaotic control. Besides, it realized chaotic system synchronization with unknown parameters of system by using matrix configuration method. Numerical simulation confirms the efficiency of the two designed controllers. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Signal Processing is the property of Journal of Signal Processing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper investigated a novel three-dimensional autonomous chaotic system. Theoretical analysis and computer simulations show that the system has an abundant chaotic behavior. Furthermore, based on the active control theory and sliding mode control theory, it proposed an active sliding mode controller. The new chaotic systems realized anti-synchronization in the above controller. Next, based on Lyapunov stability theory and adaptive control method, it gave the expression of adaptive controller and the updating rule of parameters. Different dimensions of chaotic systems with unknown parameters achieve generalized synchronization in the add-dimension method. Eventually, it validated the above theoretic results in numerical simulations. [ABSTRACT FROM AUTHOR]

For the problems that image encryption algorithm has high complexity and poor security, this paper presented a novel image encryption algorithm based on chaotic system and DNA sequence operation. This algorithm integrated chaotic system with DNA sequence operation (elongation, truncation, deletion, and insertion operation) through studying the correlation algorithms, and then, according to DNA sequence operation, it implemented DNA addition operation to the original images by Chen and Lorenz chaotic systems, finally got the encrypted image successfully. Simulation results demonstrate that this algorithm not only shows good encryption effect, high security and large key, but also has the advantages of good initial sensitivity and anti-decryption attack in contrast to other algorithms. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presented a novel watermarking algorithm based on binary-grouping. It transformed the original image by block and chose some middle frequency bands of the DCT coefficients as position space for embedding. The scrambled watermark was converted into hexadecimal values which were mapped to coefficients in position space. Then, modified these coefficients and complete the embedding. The proposed algorithm can achieve the same effect using more less coefficients changing than traditional DCT algorithms. Experimental results show that the embedding positions are randomly selected by the secret key, and the invisibility and robustness of the proposed watermarking algorithm. [ABSTRACT FROM AUTHOR]

This paper studied globally exponentially attractive set of a chaotic system. The globally exponentially attractive set of this system is investigated via constructing a Lyapunov function and optimation theory. A five dimensional ellipsoidal globally exponentially attractive set is derived, and numerical simulations are presented to show the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]