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Calcination-free synthesis of high strength self-cleaning anti-reflective MgF2-TiO2 coating
摘要： In order to understand the nonlinear dynamic behavior of a planar mechanism with clearance, the nonlinear dynamic model of the 2-DOF nine-bar mechanism with a revolute clearance is proposed; the dynamic response, phase diagrams, Poincar′e portraits, and largest Lyapunov exponents (LLEs) of mechanism are investigated. The nonlinear dynamic model of 2-DOF nine-bar mechanism containing a revolute clearance is established by using the Lagrange equation. Dynamic response of the slider’s kinematics characteristic, contact force, driving torque, shaft center trajectory, and the penetration depth for 2-DOF nine-bar mechanism are all analyzed. Chaos phenomenon existed in the mechanism has been identi?ed by using the phase diagrams, the Poincar′e portraits, and LLEs. The e?ects of the di?erent clearance sizes, di?erent friction coe?cients, and di?erent driving speeds on dynamic behavior are studied. Bifurcation diagrams with changing clearance value, friction coe?cient, and driving speed are drawn. The research could provide important technical support and theoretical basis for the further study of the nonlinear dynamics of planar mechanism.
关键词： Lyapunov exponent,nonlinear dynamics,chaos,clearance joint,bifurcation
更新于2025-09-23 15:23:52
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Adaptive Pixel-Selection Fractional Chaotic Map Lattices for image cryptography
摘要： Chaotic theory has been employed in cryptography application for establishing a sequence of data closest to pseudorandom number. Image cryptography with Chaotic Map Lattices (CML) uses the chaos parameters, the number of iterations and the number of cycles for encryption as secret keys. Amount of secret keys has a great impact on security in cryptography. Adaptive Pixel-Selection Fractional Chaotic Map Lattices (APFCML) enhances the encryption security by introducing a novel non-integer fractional order concept as secret keys. Fractional chaos is modified chaos with a fractional differential equation containing derivatives of non-integer order. A non-integer order has an effect on the range of chaos's parameter. Moreover, the encryption sequence has been adaptively selected based on another chaos generator. In the experiments, the measurement indices of originality preservation, visual inspection, and statistical analysis are used to evaluate the performance of the proposed APFCML compared to that of the original CML.
关键词： fractional logistic,bifurcation diagram,image cryptography,Lyapunov exponent,Chaotic
更新于2025-09-23 15:19:57