On the use of signal smoothness estimates and signal similarity in bearing fault detection

The concepts of signal smoothness and signal similarity are very common in digital signal processing. In this paper, both concepts have been explored in the ball bearing failure diagnostics, where the bearing fault, bearing inner race and outer race faults were analysed. It was found out that the signal smoothness and the signal similarity estimates might reduce computational tolerance in the vibro-acoustic signal analysis. On this basis, numerous experiments have been carried out to demonstrate usefulness of the above-mentioned estimates (as useful parameters of signal features) in the signal quality analysis

Dynamic visual cryptography scheme on the surface of a vibrating structure

Dynamic visual cryptography scheme based on time-averaged fringes generated by Ronchi-type geometric moiré gratings on finite element grids is proposed in this paper. A single cover image is used to encode the secret image and is formed on the surface of a deformable structure. Time-averaged moiré fringes leak the secret when the structure is oscillated according to a predefined Eigen-shape. The envelope functions determining the motion induced blur of the Ronchi-type moiré grating depend on the characteristic features of the motion. And though harmonic oscillations do not result into a completely uniform time-averaged image of the Ronchi-moiré grating, initial phase scrambling and phase normalization algorithms are used to encode the secret in the cover image. Theoretical relationships between the amplitude of the Eigen-shape, the order of the not completely developed time-averaged fringe and the pitch of the deformable one-dimensional Ronchi-type moiré grating are derived

Image hiding in dynamic unstable self-organizing patterns

A digital image hiding scheme based on the breakup of spiral waves is presented in this paper. This scheme does not require initial conditions perturbation and embedding of the secret image is done during the evolution of a self-organizing pattern. Such features increase the security, but still enable an effective decoding of the secret image. The concept of the order of a 2D linear recurrent sequences are used to estimate the complexity of the pattern and select the optimal timing required for the pattern to complete. Computational experiments are used to demonstrate the properties and efficiency of the proposed scheme

Image Hiding Scheme Based on the Atrial Fibrillation Model

An image communication scheme based on the atrial fibrillation (AF) model is presented in this paper. Self-organizing patterns produced by the AF model are used to hide and transmit secret visual information. A secret image is encoded into the random matrix of initial cell excitation states in the form of a dot-skeleton representation. Self-organized patterns produced by such initial cell states ensure a secure and efficient transmission of secret visual images. Procedures for digital encoding and decoding of secret images, as well as the sensitivity of the communication scheme to the perturbation of the AF model’s parameters are discussed in the paper