Structurally parametric identification of object descrete models with delay for tuning smith controllers

Construction of Smith digital controller on the basis of equivalence principle of dynamic object models with delay has been suggeste

Stable two-dimensional soliton complexes in Bose-Einstein condensates with helicoidal spin-orbit coupling

We show that attractive two-dimensional spinor Bose-Einstein condensates with helicoidal spatially periodic spin-orbit coupling (SOC) support a rich variety of stable fundamental solitons and bound soliton complexes. Such states exist with chemical potentials belonging to the semi-infinite gap in the band spectrum created by the periodically modulated SOC. All these states exist above a certain threshold value of the norm. The chemical potential of fundamental solitons attains the bottom of the lowest band, whose locus is a ring in the space of Bloch momenta, and the radius of the ring is a non-monotonous function of the SOC strength. The chemical potential of soliton complexes does not attain the band edge. The complexes are bound states of several out-of-phase fundamental solitons whose centers are placed at local maxima of the SOC-modulation phase. In this sense, the impact of the helicoidal SOC landscape on the solitons is similar to that of a periodic two-dimensional potential. In particular, it can compensate repulsive forces between out-of-phase solitons, making their bound states stable. Extended stability domains are found for complexes built of two and four solitons (dipoles and quadrupoles, respectively). They are typically stable below a critical value of the chemical potential.Comment: minor corrections, published version, 2020 New J. Phys. 22 10301

Stable multicolor periodic-wave arrays

We study the existence and stability of cnoidal periodic wave arrays propagating in uniform quadratic nonlinear media and discover that they become completely stable above a threshold light intensity. To the best of our knowledge, this is the first example in physics of completely stable periodic wave patterns propagating in conservative uniform media supporting bright solitons.Comment: 12 pages, 3 figure

The semi-Markov model for the ‘technological module–storage device’ structure

The theory of semi-Markov processes has been used to design a model of a ‘technological module–storage device’ (TM–SD) structure. Stationary characteristics based on the obtained equations were determined to find a stationary distribution of the Markov embedded chain. Relying upon the performed studies, the stationary distribution of a semi-Markov process was determined. This allowed calculating the availability ratio of the TM–SD structure, and the design formula was given. The Markov restoration equations for the TM–SD system with taking into account TM and SD failures were solved assuming the exponential behavior of these failures. The obtained expressions describe how such a system operates and allow substituting the TM–SD system with an equivalent element with two factor states. This result significantly simplifies the modeling problem for more complex systems. The legitimacy of using exponential distributions of random variables (error-free periods for TM and SD) was analyzed. The performed simulation modeling revealed that the hypothesis for an exponential behavior of error-free periods for TM as a whole (and SD as well) can be accepted even in the case when TM (or SD) consists of six nodes

HIGH-POROUS CERAMIC COMPOSITE MATERIALS BASED ON Cd2Zr2O7

The process of preparing a porous composite ceramic material based on gadolinium zirconate, including the synthesis of foam-cryogel with the addition of Cd2Zr2O7 – ceramic fiber, freezing, drying and sintering was investigated