arXiv subjects

Andrey Polyakov

Publications and source records attributed to Andrey Polyakov.

22 records · Page 2Linked to original sources

arXiv2022

Finite- and Fixed-Time Nonovershooting Stabilizers and Safety Filters by Homogeneous Feedback

Non-overshooting stabilization is a form of safe control where the setpoint chosen by the user is at the boundary of the safe set. Exponential non-overshooting stabilization, including suitable extensions to systems with deterministic and stochastic disturbances, has been solved by the second author and his coauthors. In this paper we develop homogeneous feedback laws for fixed-time nonovershooting stabilization for nonlinear systems that are input-output linearizable with a full relative degree, i.e., for systems that are diffeomorphically equivalent to the chain of integrators. These homogeneous feedback laws can also assume the secondary role of `fixed-time safety filters' (FxTSf filters) which keep the system within the closed safe set for all time but, in the case where the user's nominal control commands approach to the unsafe set, allow the system to reach the boundary of the safe set no later than a desired time that is independent of nominal control and independent of the value of the state at the time the nominal control begins to be overridden.

eess.SY↗

arXiv2021

Adaptive Finite-time and Fixed-time Control Design using Output Stability Conditions

The present paper provides a sufficient condition to ensure output finite-time and fixed-time stability. Comparing with analogous researches the proposed result is less restrictive and obtained for a wider class of systems. The presented output stability condition is used for adaptive control design, where the state vector of a plant is extended by adjustable control parameters.

math.OC↗

arXiv2020

Fermi surface chirality induced in a TaSe$_{2}$ monosheet formed by a Ta/ Bi$_{2}$Se$_{3}$ interface reaction

Spin-momentum locking in topological insulators and materials with Rashba-type interactions is an extremely attractive feature for novel spintronic devices and is therefore under intense investigation. Significant efforts are underway to identify new material systems with spin-momentum locking, but also to create heterostructures with new spintronic functionalities. In the present study we address both subjects and investigate a van der Waals-type heterostructure consisting of the topological insulator Bi$_{2}$Se$_{3}$ and a single Se-Ta-Se triple-layer (TL) of H-type TaSe$_{2}$ grown by a novel method which exploits an interface reaction between the adsorbed metal and selenium. We then show, using surface x-ray diffraction, that the symmetry of the TaSe2-like TL is reduced from D$_{3h}$ to C$_{3v}$ resulting from a vertical atomic shift of the tantalum atom. Spin- and angle-resolved photoemission indicates that, owing to the symmetry lowering, the states at the Fermi surface acquire an in-plane spin component forming a surface contour with a helical Rashba-like spin texture, which is coupled to the Dirac cone of the substrate. Our approach provides a new route to realize novel chiral two-dimensional electron systems via interface engineering that do not exist in the corresponding bulk materials.

cond-mat.mes-hall↗

arXiv2019

Parallel Algorithm for Time Series Discords Discovery on the Intel Xeon Phi Knights Landing Many-core Processor

Discord is a refinement of the concept of anomalous subsequence of a time series. The task of discords discovery is applied in a wide range of subject domains related to time series: medicine, economics, climate modeling, etc. In this paper, we propose a novel parallel algorithm for discords discovery for the Intel Xeon Phi Knights Landing (KNL) many-core systems for the case when input data fit in main memory. The algorithm exploits the ability to independently calculate Euclidean distances between the subsequences of the time series. Computations are paralleled through OpenMP technology. The algorithm consists of two stages, namely precomputations and discovery. At the precomputations stage, we construct the auxiliary matrix data structures, which ensure efficient vectorization of computations on Intel Xeon Phi KNL. At the discovery stage, the algorithm finds discord based upon the structures above. Experimental evaluation confirms the high scalability of the developed algorithm.

cs.DC↗