Wang Xing-Yuan

Fractal image compression based on spatial correlation and hybrid genetic algorithm

1047-3203/

Generalized synchronization via nonlinear control.

see front matter 2009 Elsevier Inc. A doi:10.1016/j.jvcir.2009.07.002 * Corresponding author. E-mail address: wangxy@dlut.edu.cn (W. Xing-yua In order to solve the high complexity of the conventional encoding scheme for fractal image compression, a spatial correlation hybrid genetic algorithm based on the characteristics of fractal and partitioned iterated function system (PIFS) is proposed in this paper. There are two stages for the algorithm: (1) Make use of spatial correlation in images for both range and domain pool to exploit local optima. (2) Adopt simulated annealing genetic algorithm (SAGA) to explore the global optima if the local optima are not satisfied. In order to avoid premature convergence, the algorithm adopt dyadic mutation operator to take place of the traditional one. Experiment results show that the algorithm convergent rapidly. At the premise of good quality of the reconstructed image, the algorithm saved the encoding time and obtained high compression ratio. 2009 Elsevier Inc. All rights reserved.

Geometrically invariant image watermarking based on fast Radial Harmonic Fourier Moments

In this paper, the generalized synchronization problem of drive-response systems is investigated. Using the drive-response concept and the nonlinear control theory, a control law is designed to achieve the generalized synchronization of chaotic systems. Based on the Lyapunov stability theory, a generalized synchronization condition is derived. Theoretical analyses and numerical simulations further demonstrate the feasibility and effectiveness of the proposed technique.

A secure key agreement protocol based on chaotic maps

In order to reduce the time complexity and improve the reconstruction performance of traditional method for Radial Harmonic Fourier Moments (RHFMs), we introduce a fast and precise method by using FFT and based on the which, this paper proposes a novel image watermarking algorithm which is robust to geometric attacks. We firstly compute the RHFMs of the original image by using the proposed method and select the robust RHFMs which are suitable for watermark embedding. Then the watermark is embedded by modifying the magnitudes of RHFMs based on quantization. In the decoder, the watermark can be extracted from the magnitudes of RHFMs directly without using the original image. Simulation results show the proposed algorithm provides an excellent watermark invisibility and can be resilient to geometric attacks and common image processing attacks effectively. & 2016 Elsevier B.V. All rights reserved.

Researches on chaos phenomenon of EEG dynamics model

To guarantee the security of communication in the public channel, many key agreement protocols have been proposed. Recently, Gong et al. proposed a key agreement protocol based on chaotic maps with password sharing. In this paper, Gong et al.’s protocol is analyzed, and we find that this protocol exhibits key management issues and potential security problems. Furthermore, the paper presents a new key agreement protocol based on enhanced Chebyshev polynomials to overcome these problems. Through our analysis, our key agreement protocol not only provides mutual authentication and the ability to resist a variety of common attacks, but also solve the problems of key management and security issues existing in Gong et al.’s protocol.

Chaos Control and Synchronization of Cellular Neural Network with Delays Based on OPNCL Control

According to phase space reconstruct technique from one-dimensional time series and the quantitative criterion and rule of system chaos, analyses and computations are conducted on EEG (electroencephalogram) dynamics model. Based on the comparative studies of the phase graph, the power spectra, the computation of the correlation dimension and the Lyapunov exponent to EEG signals from the model, the following conclusions are shown: (i) Chaotic patterns of the dynamics model may emerge out of Pomeau-Manneville route, and relevant to double-periodic bifurcation, Hopf bifurcation, and reverse bifurcation; (ii) To further support the view that chaos exist in EEG signals.

Lasing Enhanced Surface Plasmon Resonance Sensing

The problem of chaos control and complete synchronization of cellular neural network with delays is studied. Based on the open plus nonlinear closed loop (OPNCL) method, the control scheme and synchronization scheme are designed. Both the schemes can achieve the chaos control and complete synchronization of chaotic neural network respectively, and their validity is further verified by numerical simulation experiments.

GENERALIZED SYNCHRONIZATION OF FRACTIONAL ORDER CHAOTIC SYSTEMS

Abstract The resonance phenomena of surface plasmons has enabled development of a novel class of noncontact, real-time and label-free optical sensors, which have emerged as a prominent tool in biochemical sensing and detection. However, various forms of surface plasmon resonances occur with natively strong non-radiative Drude damping that weakens the resonance and limits the sensing performance fundamentally. Here we experimentally demonstrate the first lasing-enhanced surface plasmon resonance (LESPR) refractive index sensor. The figure of merit (FOM) of intensity sensing is ~84,000, which is about 400 times higher than state-of-the-art surface plasmon resonance (SPR) sensor. We found that the high FOM originates from three unique features of LESPR sensors: high-quality factor, nearly zero background emission and the Gaussian-shaped lasing spectra. The LESPR sensors may form the basis for a novel class of plasmonic sensors with unprecedented performance for a broad range of applications.

Observer-based adaptive fuzzy synchronization for hyperchaotic systems.

In the paper, generalized chaotic synchronization of a class of fractional order systems is studied. Based on the stability theory of linear fractional order systems, a generalized synchronization scheme is presented, and theoretical analysis is provided to verify its feasibility. The proposed method can realize generalized synchronization not only of fractional order systems with same dimension, but also of systems with different dimensions. Besides, the function relation of generalized synchronization can be linear or nonlinear. Numerical simulations show the effectiveness of the scheme.

A Novel True Random Number Generator Based on Mouse Movement and a One-Dimensional Chaotic Map

In this paper, the synchronization problem of hyperchaotic systems is investigated. An adaptive fuzzy observer is proposed based on the Takagi-Sugeno fuzzy model. Theoretical analysis based on Lyapunov stability theory is provided to verify the feasibility of the proposed synchronization scheme. Numerical simulation of the hyperchaotic Lü system is given to demonstrate the application of the proposed scheme. The form of the proposed scheme is simple, and it is general and robust.