Showing papers by "Aleksey Kudreyko published in 2021"

Generalized Cauchy Degradation Model With Long-Range Dependence and Maximum Lyapunov Exponent for Remaining Useful Life

Abstract: A new long-range-dependent (LRD) degradation model is described based on the generalized Cauchy (GC) process. The GC process is a two-parameter model, which describes local irregularities and global correlation characteristics of the data time sequence by the Hurst parameter $H$ and fractal dimension $D$ . Compared with the fractional Brownian motion (fBm) with linear relationship $H=2-D$ , two parameters of the GC process are independent of each other. The GC process is taken as the diffusion term to describe the LRD characteristics and uncertainty of the degradation process, and the degradation model is established in the form of power law and exponential drift. The Gaussian assumption of the GC process allows us to use linear system theory and statistics to derive its incremental distribution for obtaining the difference iteration form of the GC degradation model. Besides, the dimensionless factors, the principal component analysis (PCA), and the iterative method are used to eliminate the interference of noise on the degradation data. Then, the maximum prediction range of the GC degradation model in the degradation sequence is obtained by the reciprocal of the maximum Lyapunov exponent. Finally, the GC degradation model was applied for prediction of the remaining useful life (RUL) of rolling bearing. The validity of the GC degradation model is verified.

Discrete breathers in a triangular β-Fermi-Pasta-Ulam-Tsingou lattice.

Abstract: A practical approach to the search for (quasi-) discrete breathers (DBs) in a triangular $\ensuremath{\beta}$-FPUT lattice (after Fermi, Pasta, Ulam, and Tsingou) is proposed. DBs are obtained by superimposing localizing functions on delocalized nonlinear vibrational modes (DNVMs) having frequencies above the phonon spectrum of the lattice. Zero-dimensional and one-dimensional DBs are obtained. The former ones are localized in both spatial dimensions, and the latter ones are only in one dimension. Among the one-dimensional DBs, two families are considered: the first is based on the DNVMs of a triangular lattice, and the second is based on the DNVMs of a chain. We speculate that our systematic approach on the triangular $\ensuremath{\beta}$-FPUT lattice reveals all possible types of spatially localized oscillations with frequencies bifurcating from the upper edge of the phonon band as all DNVMs with frequencies above the phonon band are analyzed.

Patterned Photoalignment in Thin Films: Physics and Applications

Abstract: Photoalignment of liquid crystals by using azo dye molecules is a commonly proposed alternative to traditional rubbing alignment methods. Photoalignment mechanism can be well described in terms of rotational diffusion of azo dye molecules exposed by ultraviolet polarized light. A specific feature of the irradiated light is the intensity dependent change of azimuthal anchoring of liquid crystals. While there are various mechanisms of azo dye photoalignment, photo-reorientation occurs when dye molecules orient themselves perpendicular to the polarization of incident light. In this review, we describe both recent achievements in applications of photoaligned liquid crystal cells and its simulation. A variety of display and photonic devices with azo dye aligned nematic and ferroelectric liquid crystals are presented: q-plates, optically rewritable flexible e-paper (monochromatic and color), and Dammann gratings. Some theoretical aspects of the alignment process and display simulation are also considered.

Tunable optical properties for ORW e-paper

Abstract: Reflective liquid crystal displays are attracting attention as portable information systems because of zero- or extremely low power consumption. In this study, we deal with an electrode-free reflec...

Optically Rewritable Liquid Crystal Displays: Characteristics and Performance

Abstract: Recent achievements in the photoalignment technique for fabrication of optically rewritable electronic paper with high performance characteristics are surveyed with emphasis on temporal constraints on the exposure process. The possibility of creating electrode-free electronic paper has very important practical aspects. However, many existing studies do not include sufficient analysis on how to achieve acceptable reflective characteristics within short exposure time. In order to achieve this goal, we have applied the rotational diffusion model. We find that the parameters of the diffusion model can be adjusted to get acceptable light-reflecting characteristics within 10 s of exposure. In comparison with the long-time exposure, the reflectance coefficient reduces by 24%. The route to material improvements for optimized e-paper device is discussed.

Optimization of image writer modes for optically rewritable electronic paper

Abstract: Time-limited exposure of electrode-free optically rewritable electronic paper is essential for applications, but performance characteristics can be modest. In this study we investigate whether imag...