Complexity and meaning in nonlinear dynamical systems

Measures of complexity and meaning in nonlinear dynamical systems are presented, applied to specific examples, and compared with each other. A basic conceptual and operational equivalence of both kinds of measures is described. This equivalence substantiates earlier indications by Atlan and Grassberger for a close relationship between complexity and meaning. Both concepts are suggested as candidates to demonstrate the necessity of certain extensions and modifications required to update several habitual regulative principles of the exact sciences.     

A robust and lossless DNA encryption scheme for color images

In this paper, a new robust and lossless color image encryption algorithm is presented based on DNA sequence operation and one-way coupled-map lattices (OCML). The plain-image is firstly decomposed into three gray-level components and we randomly convert them into three DNA matrices by the DNA encoding rules. Then the XOR operation is performed on the DNA matrices for two times. Next, the shuffled DNA matrices are transformed into three gray images according to the DNA decoding rules. Finally, a diffusion process is further applied to change the image pixel’s values by a key stream, and the cipher-image is attained. The key stream generated by OCML is related to the plain-image. Experimental results and security analysis demonstrate that the proposed algorithm has a good encryption effect and can withstand various typical attacks. Furthermore, it is robust against some common image processing operations such as noise adding, cropping, JPEG compression etc.

     

Slowing down critical transitions via Gaussian white noise and periodic force

Stochastic perturbations and periodic excitations are generally regarded as sources to induce critical transitions in complex systems. However, we find that they are also able to slow down an imminent critical transition. To illustrate this phenomenon, a periodically driven bistable eutrophication model with Gaussian white noise is introduced as a prototype class of real systems.The residence probability(RP) is presented to measure the possibility that the given system stays in the oligotrophic state versus Gaussian white noise and periodic force. Variations in the mean first passage time(MFPT) and the mean velocity(MV) of the first right-crossing process are also calculated respectively. We show that the frequency of the periodic force can increase the MFPT while reduce the MV under different control parameters. Nevertheless, the noise intensity or the amplitude may result in an increase of the RP only in the case of control parameters approaching the critical values. Furthermore, for an impending critical transition, an increase of the RP appears with the interaction between the amplitude and noise intensity or the combination of the noise intensity and frequency, while the interaction of the frequency and amplitude leads to an extension of the MFPT or a decrease of the MV. As a result, an increase of the RP and MFPT, and a decrease of the MVobtained from our results claim that it is possible to slow down an imminent critical transition via Gaussian white noise and periodic force.     

Finite-time Consensus of Leader-following Multi-agent Systems with Multiple Time Delays over Time-varying Topology

This paper studies the finite-time consensus of leader-following multi-agent systems with multiple time delays over time-varying topology. The finite-time     

Wavelet Spectrum and Self-Organizing Maps-Based Approach for Hydrologic Regionalization -a Case Study in the Western United States

Water Resources Management - Hydrologic regionalization deals with the investigation of homogeneity in watersheds and provides a classification of watersheds for regional analysis. The...