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This paper introduces a new multi-image cryptosystem based on modified Henon map and nonlinear combination of chaotic seed maps. Based on the degree of correlation between the adjacent pixels of the plain image, a unique weight is assigned to the plain image. First, the coordinates of plain images are disrupted by modified Henon map as confusion phase. In the first step of diffusion phase, the pixels content of images are changed separately by XOR operation between confused images and matrices with suitable nonlinear combination of seed maps sequences. These combination of seed maps are selected depending on the weight of plain images as well as bifurcation properties of mentioned chaotic maps. After concatenating the matrices obtained from the first step of diffusion phase, the bitwise XOR operation is applied between newly developed matrix and the other produced matrix from the chaotic sequences of the Logistic-Tent-Sine hybrid system, as second step of diffusion phase. The encrypted image is obtained after applying shift and exchange operations. The results of the implementation using graphs and histograms show that the proposed scheme, compared to some existing methods, can effectively resist common attacks and can be used as a secure method for encrypting digital images.

An automatic method of detection of transients, step changes and slope changes in time series is developed based on a modified form of the EWMA forecasting algorithm. A backward CUSUM scheme is used to detect changes in the behaviour of the series and criteria are developed to assess automatically whether the change is a transient, step change, slope change or a false alarm. The forecasting algorithm is then automatically amended in the light of the determined change. The performance of the resulting system is compared with straightforward Box–Jenkins modelling and forecasting and also with the multistate Bayesian forecasting approach.

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Abstract:Due to energy resources constraint in wireless sensor networks, balancing energy consumption is very important in increasing the network life time. In this paper, the new hierarchical and dynamic routing algorithm is proposed to balance energy consumption among the nodes and to prevent from energy holing problem. Simulation results show that the proposed algorithm prolongs the network lifetime about 40% compared to the LEACH protocol.