In this paper,we first propose a memristive chaotic system and implement it by circuit simulation.The chaotic dynamics and various attractors are analysed by using phase portrait,bifurcation diagram,and Lyapunov expon...In this paper,we first propose a memristive chaotic system and implement it by circuit simulation.The chaotic dynamics and various attractors are analysed by using phase portrait,bifurcation diagram,and Lyapunov exponents.In particular,the system has robust chaos in a wide parameter range and the initial value space,which is favourable to the security communication application.Consequently,we further explore its application in image encryption and present a new scheme.Before image processing,the external key is protected by the Grain-128a algorithm and the initial values of the memristive system are updated with the plain image.We not only perform random pixel extraction and masking with the chaotic cipher,but also use them as control parameters for Brownian motion to obtain the permutation matrix.In addition,multiplication on the finite field GF(2^(8))is added to further enhance the cryptography.Finally,the simulation results verify that the proposed image encryption scheme has better performance and higher security,which can effectively resist various attacks.展开更多
In this work, we introduce a method of fingerprint directional image partitioning based on GA. According to the fingerprint topology, A set of dynamic partition masks and a cost estimating function are designed to gui...In this work, we introduce a method of fingerprint directional image partitioning based on GA. According to the fingerprint topology, A set of dynamic partition masks and a cost estimating function are designed to guide the partitioning procedure. Finding best fitted mask application is converted to an functional optimizing problem, and we give out a GA solution to the problem. At last, we discuss the application of the proposed method in Fingerprint Classification.展开更多
The hydrodynamics and locomotion mechanism of Euglena Gracilis(E.Gracilis)is investigated using microscopic shadow imaging and micro particle image velocimetry(MicroPIV).Three distinct locomotion modes were observed:t...The hydrodynamics and locomotion mechanism of Euglena Gracilis(E.Gracilis)is investigated using microscopic shadow imaging and micro particle image velocimetry(MicroPIV).Three distinct locomotion modes were observed:translation,spin,and left/right turn.Since the flagellum was not possible to image,the strokes were identified by evaluating the flow field around the protist.The flow field information is obtained using a phase-separated PIV evaluation,which uses a histogram-thresholding based dynamic masking approach.The temporal resolution of the experiment was sufficient to identify the sequence of two modes,translation and spin,and the stroke-pulling frequency.The flow field result during a stroke is compared with existing Stokeslet dipole theories and flow disturbance decay with distance is investigated.The results indicate that the organism has a complex locomotion technique that allows the change of direction,axial orientation and propulsion.展开更多
基金This work was supported by the National Natural Science Foundation of China(61203004)the Natural Science Foundation of Heilongjiang Province(F201220)the Heilongjiang Provincial Natural Science Foundation of Joint Guidance Project(LH2020F022).
文摘In this paper,we first propose a memristive chaotic system and implement it by circuit simulation.The chaotic dynamics and various attractors are analysed by using phase portrait,bifurcation diagram,and Lyapunov exponents.In particular,the system has robust chaos in a wide parameter range and the initial value space,which is favourable to the security communication application.Consequently,we further explore its application in image encryption and present a new scheme.Before image processing,the external key is protected by the Grain-128a algorithm and the initial values of the memristive system are updated with the plain image.We not only perform random pixel extraction and masking with the chaotic cipher,but also use them as control parameters for Brownian motion to obtain the permutation matrix.In addition,multiplication on the finite field GF(2^(8))is added to further enhance the cryptography.Finally,the simulation results verify that the proposed image encryption scheme has better performance and higher security,which can effectively resist various attacks.
文摘In this work, we introduce a method of fingerprint directional image partitioning based on GA. According to the fingerprint topology, A set of dynamic partition masks and a cost estimating function are designed to guide the partitioning procedure. Finding best fitted mask application is converted to an functional optimizing problem, and we give out a GA solution to the problem. At last, we discuss the application of the proposed method in Fingerprint Classification.
文摘The hydrodynamics and locomotion mechanism of Euglena Gracilis(E.Gracilis)is investigated using microscopic shadow imaging and micro particle image velocimetry(MicroPIV).Three distinct locomotion modes were observed:translation,spin,and left/right turn.Since the flagellum was not possible to image,the strokes were identified by evaluating the flow field around the protist.The flow field information is obtained using a phase-separated PIV evaluation,which uses a histogram-thresholding based dynamic masking approach.The temporal resolution of the experiment was sufficient to identify the sequence of two modes,translation and spin,and the stroke-pulling frequency.The flow field result during a stroke is compared with existing Stokeslet dipole theories and flow disturbance decay with distance is investigated.The results indicate that the organism has a complex locomotion technique that allows the change of direction,axial orientation and propulsion.
