This study proposes a chaos‐based image encryption scheme using Henon map and Lorenz equation with multiple levels of diffusion. The Henon map is used for confusion and the Lorenz equation for diffusion. Apart from the Lorenz equation, another matrix with the same size as the original image is generated which is a complex function of the original image. This matrix which is configured as a diffusion matrix permits two stages of diffusion. Due to this step, there is a strong sensitivity to input image. This encryption algorithm has high key space, entropy very close to eight (for grey images) and very less correlation among adjacent pixels. The highlight of this method is the ideal number of pixels change rate and unified average changing intensity it offers. These ideal values indicate that the encrypted images produced by this proposed scheme are random‐like. Further, a cryptanalysis study has been carried out to prove that the proposed algorithm is resistant to known attacks.
This study presents a hybrid technique that offers constant power operation for single-phase grid-tied photovoltaic (PV) systems while performing maximum power point tracking function. A boost converter and a line commutated inverter (LCI) have been used for interfacing PV array with utility grid. Fixed firing angle of the LCI keeps the dc-link voltage constant and the boost converter extracts maximum power from the solar PV array by simply adjusting the duty ratio of the boost converter. A lowcapacity battery bank connected at the dc link is used to deliver constant power to grid. Harmonic filter is eliminated as the system inherently delivers quality supply with reduced current harmonics. PIC microcontrollers have been programmed for generating pulses to the inverter and the boost converter. The system has been simulated in MATLAB/Simulink and the simulation results are presented. The parameters of a PV panel rated for 100 W, 21.5 V and 6.83 A have been used for the simulation. Experiments have been conducted on the 21.5 V, 6.83 A PV panel for obtaining a constant power of 80 W with varying irradiation and the results correlate with the simulation study. Nomenclature L dc , R dc dc-link inductance (mH) and internal resistance (Ω) L crit critical value of dc-link inductance (mH) V oc , I sc open circuit voltage (V), and short circuit current (A) of the PV panel, respectively V pv , I pv output voltage (V) and current (A) of the PV panel on load, respectively P pv output power (W) of the PV panel on load (W) V dc , I dc dc bus voltage (equal to battery voltage) (V) and dc-link current (A), respectively I bc boost converter output current (A) I batt charging/discharging current through battery (A) I ch charging current supplied by the charger (A) V av average voltage at the dc link (V)
In this paper, a new image encryption algorithm employing the combination of chaos and cellular automata is proposed. The proposed algorithm consists of both permutation and diffusion stages. While the permutation process is carried out using logistic map and Conway's game-of-life cellular automata, the diffusion process is carried out using Chebyshev map and Lorenz equation. Further, a complex matrix generated from the plain image is used as an additional component in the diffusion process, which enables the encrypted image to exhibit a strong sensitivity to the input image. The proposed algorithm has been tested with various input images, and the performance is compared with other existing algorithms. The performance metrics obtained on the developed algorithm such as high key space, ideal number of pixels change rate and unified average changing intensity values, and very less correlation among the adjacent pixels demonstrate the high effectiveness and security features of the proposed algorithm.
This paper proposes the analysis of power enhancement in partially shaded PV system supplying DC microgrid employing micro converters with a modified Perturb and Observe (P & O) based on Maximum Power Point Tracking (MPPT) technique by sensing the load parameters alone. The proposed technique is effective in power tracking under both normal and partially shaded conditions with the reduced number of sensing devices as compared to those used in the conventional DMPPT (Distributed Maximum Power Point Tracking) techniques. In this work, two series configured micro converters are considered for supplying 120 V DC microgrid from partially shaded PV panels. The complete steady-state analysis is developed and predicted the performance of the proposed MPPT operation and compared with the simulation and experimental results. The PV panels are emulated in the experiments. The effectiveness of the proposed technique is demonstrated and substantiated by theoretical, simulation and experimental results under various operating conditions.
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