Search results for: A. A. Fedotov

Items from 1 to 20 out of 54 results

article

On Adiabatic Normal Modes in a Wedge-Shaped Sea

A. A. Fedotov

Journal of Mathematical Sciences > 2019 > 243 > 5 > 808-824

A two-dimensional problem that is a model for sound propagation in a narrow water wedge near the shore of a sea is studied. A solution to the Helmholtz equation, which is asymptotically a normal wave propagating along “water” wedge to the “shore,” is constructed explicitly. The solution satisfies the Helmholtz equation in the quadrant one side of which is “the surface of the water” and the second...

article

Techniques for the Morphological Analysis of the Pulse Wave

A. A. Fedotov

Biomedical Engineering > 2019 > 53 > 4 > 270-274

A new technique for contour analysis of the pulse wave signal is proposed. It is based on spectral analysis of a sequence of replicated pulse waveforms. Comparative analysis of the sensitivity and specificity of the proposed indices was carried out in a sample of 45 volunteers of different ages and states of arterial health. It was found that the proposed spectral index has higher sensitivity (89%)...

article

Noise Immunity of Pulse Wave Contour Analysis

A. A. Fedotov

Measurement Techniques > 2019 > 62 > 3 > 289-293

This article is devoted to analyzing the noise immunity of pulse waveform contour analysis. Different approaches to the implementation of the pulse waveform contour analysis were considered. It was demonstrated that a classical approach for the morphological analysis of the pulse wave based on using the stiffness index and the reflection index do not provide sufficient diagnostic accuracy due to the...

article

Experimental Study of the Fatigue Stiffness Degradation for the Carbon Fiber Reinforced Plastic at Variable Temperature

A. A. Fedotov, A. E. Tsipenko

Russian Aeronautics > 2019 > 62 > 1 > 14-21

The paper represents the results of the experimental study on variation of the longitudinal elastic modulus and Poisson’s ratio for the carbon fiber specimens under fatigue loading at variable temperature. The approximating relations reflecting the test data are proposed.

article

The Influence of Stabilizer on the Formation and Tribotechnical Properties of Cu Nanoparticles

A. A. Kuzharov, A. A. Milov, Yu. S. Gerasina, I. Yu. Neverov, more

Protection of Metals and Physical Chemistry of Surfaces > 2019 > 55 > 2 > 283-287

The good wear-resistance of state-of-the-art liquid lubricants is due to the formation of complex metal and organometallic films onto the friction surface, reducing the friction and wear. For this purpose, various additives of metal nanopowders are used, especially ones based on copper. The formation and growth of Cu nanoparticles, as well as the tribotechnical characteristics of lubricants, are mainly...

article

On Minimal Entire Solutions of the One-Dimensional Difference Schrödinger Equation with the Potential υ(z) = e^−2πiz

A. A. Fedotov

Journal of Mathematical Sciences > 2019 > 238 > 5 > 750-761

Let z ∈ ℂ be a complex variable, and let h ∈ (0, 1) and p ∈ ℂ be parameters. For the equation ψ(z + h) + ψ(z − h) + e^−2πizψ(z) = 2 cos(2πp)ψ(z), solutions having the minimal possible growth simultaneously as Im z → ∞ and as Im z → − ∞ are studied. In particular, it is shown that they satisfy one more difference equation ψ(z + 1) + ψ(z − 1) + e^−2πiz/hψ(z) = 2 cos(2πp/h)ψ(z).

article

The Concept of a New Generation of Electrocardiogram Simulators

A. A. Fedotov

Measurement Techniques > 2019 > 61 > 12 > 1238-1243

The article is devoted to the issues of conceptual development of a new generation of electrocardiogram imitators. A mathematical model is proposed for simulating ECG signal considering the variability of biosignal morphology, the presence of various distortions and artefacts, heart rate variability and respiratory modulation of ECG signal. A block diagram of the ECG simulator was designed.

article

A Monodromy Matrix for the Almost Mathieu Equation with Small Coupling Constant

A. A. Fedotov

Functional Analysis and Its Applications > 2018 > 52 > 4 > 311-315

For the almost Mathieu operator with small coupling constant, we describe the asymptotics of a monodromy matrix and of a series of spectral gaps.

article

Myographic Interference Filtering from ECG Signals Using Multiresolution Wavelet Transform

A. A. Fedotov

Biomedical Engineering > 2019 > 52 > 5 > 344-347

Use of the multiresolution wavelet transform for the processing of ECG signals corrupted by myographic interference is considered. The influence of wavelet transform parameters on the ECG distortion level after processing is studied. The optimal parameters of the multiresolution wavelet transform are determined using criteria for minimizing distortions of processed ECG signals as compared to a model...

article

Semiclassical Asymptotics of the Spectrum of the Subcritical Harper Operator

A. A. Fedotov, E. V. Shchetka

Mathematical Notes > 2018 > 104 > 5-6 > 933-938

Original Russian Text © A. A. Fedotov, E. V. Shchetka, 2018, published in Matematicheskie Zametki, 2018, Vol. 104, No. 6, pp. 948–952.

article

Investigation of the Properties of Modified Phenol-Formaldehyde Oligomer Using IR Spectroscopy

S. A. Ugryumov, A. V. Sviridov, A. A. Fedotov

Polymer Science, Series D > 2018 > 11 > 3 > 277-279

The modification of phenol-formaldehyde oligomer with Resydrol alkyd oligomer has been proposed for the production of adhesive-bonded wood materials. The chemical processes that occur in the modified binder have been determined using IR spectroscopy. A model of chemical interaction of phenol-formaldehyde oligomer with Resydrol alkyd oligomer has been presented.

article

Estimation of Sensitivity of Nonlinear Methods for Heart Rate Variability Analysis

A. A. Fedotov

Biomedical Engineering > 2018 > 52 > 2 > 111-115

Modern mathematical methods for analysis of heart rate variability (HRV), such as rescaled range analysis, detrended fluctuation analysis, and phase-rectified signal averaging were considered. Algorithms for calculating novel nonlinear HRV indices were described in detail. Mathematical models for simulating artificial cardiac Beat-to-beat intervals that take into account various noise processes were...

article

The Virtual Coronary Angiography Method

A. A. Fedotov

Biophysics > 2018 > 63 > 2 > 254-261

This article is devoted to the development of a virtual coronary angiography method, a noninvasive method of evaluation of the state of the human coronary artery. Registration and processing of the signal of peripheral arterial blood pulsation against the background of a functional test with controlled respiration form the basis of the method. A mathematical model of the relationship between relative...

article

Monodromization and Difference Equations with Meromorphic Periodic Coefficients

A. A. Fedotov

Functional Analysis and Its Applications > 2018 > 52 > 1 > 77-81

We consider a system of two first-order difference equations in the complex plane. We assume that the matrix of the system is a 1-periodic meromorphic function having two simple poles per period and bounded as Im z → ±∞. We prove the existence and uniqueness of minimal meromorphic solutions, i.e., solutions having simultaneously a minimal set of poles and minimal possible growth as Im z → ±∞. We consider...

article

A Study of the Influence of Natural Diamond Ultrafine Powders on the Properties of Metal Matrix Composites

M. N. Safonova, A. S. Syromyatnikova, G. A. Petasyuk, A. A. Fedotov, more

Journal of Superhard Materials > 2018 > 40 > 1 > 65-72

The influence of the percentage content and dispersion of natural diamond powders used as fillers on the properties of a tin- and copper-based composite material for abrasive applications has been studied. It has been experimentally found out that adding these fillers in certain amounts to the composite has a beneficial effect on the physical-mechanical properties and performance of the resulting...

article

Correction to: Multiresolution Analysis of ECG Signals in Heart Rhythm Monitoring

A. A. Fedotov

Biomedical Engineering > 2018 > 51 > 5 > 376-376

The author’s affiliation should read Samara National Research University named after Academician S. P. Korolev, Samara, Russia.

article

A Modular System for Dynamic Monitoring of the Human Cardiorespiratory System

A. A. Fedotov, A. S. Akulova, S. A. Akulov

Biomedical Engineering > 2017 > 51 > 4 > 239-242

The main parameters and the structure of a modular system for dynamic monitoring of the human cardiorespiratory system under daily activity conditions are described. Flow diagrams of the measuring channels for electrocardiographic and respiratory monitoring are presented.

article

Theoretical and clinical assessment of the sensitivity of heart rate variability indices

A. A. Fedotov, A. S. Akulova, P. A. Lebedev

Biophysics > 2017 > 62 > 4 > 621-628

The application of modern methods of mathematical processing of non-stationary quasi-periodic data to the analysis of heart-rate variability is considered. Methods for the assessment of new parameters in non-linear variability analysis are described in detail. Mathematical models of heart rhythm are developed with the presence of various noise processes taken into account. A model of the state of...

article

Quasiclassical Asymptotics of Malyuzhinets Functions

A. A. Fedotov

Journal of Mathematical Sciences > 2017 > 226 > 6 > 810-816

A difference equation in the complex plane is considered. It is kindred to the Malyuzhinets equation. Asymptotics of its solutions are obtained under the assumption that the shift parameter in the difference equation is small. Bibliography: 7 titles.

article

Multiresolution Analysis of ECG Signals in Heart Rhythm Monitoring

A. A. Fedotov

Biomedical Engineering > 2017 > 51 > 3 > 178-182

The paper is devoted to multiresolution analysis of ECG signals in heart rhythm monitoring. The proposed method for R-wave detection in ECG signals is based on extracting detail coefficients from the wavelet decomposition of the ECG signal. It uses nonlinear transforms and the adaptive threshold algorithm. The suggested approach is compared to existing methods for R-wave detection in ECG signals used...

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Search results for: A. A. Fedotov

On Adiabatic Normal Modes in a Wedge-Shaped Sea

Techniques for the Morphological Analysis of the Pulse Wave

Noise Immunity of Pulse Wave Contour Analysis

Experimental Study of the Fatigue Stiffness Degradation for the Carbon Fiber Reinforced Plastic at Variable Temperature

The Influence of Stabilizer on the Formation and Tribotechnical Properties of Cu Nanoparticles

On Minimal Entire Solutions of the One-Dimensional Difference Schrödinger Equation with the Potential υ(z) = e^−2πiz

The Concept of a New Generation of Electrocardiogram Simulators

A Monodromy Matrix for the Almost Mathieu Equation with Small Coupling Constant

Myographic Interference Filtering from ECG Signals Using Multiresolution Wavelet Transform

Semiclassical Asymptotics of the Spectrum of the Subcritical Harper Operator

Investigation of the Properties of Modified Phenol-Formaldehyde Oligomer Using IR Spectroscopy

Estimation of Sensitivity of Nonlinear Methods for Heart Rate Variability Analysis

The Virtual Coronary Angiography Method

Monodromization and Difference Equations with Meromorphic Periodic Coefficients

A Study of the Influence of Natural Diamond Ultrafine Powders on the Properties of Metal Matrix Composites

Correction to: Multiresolution Analysis of ECG Signals in Heart Rhythm Monitoring

A Modular System for Dynamic Monitoring of the Human Cardiorespiratory System

Theoretical and clinical assessment of the sensitivity of heart rate variability indices

Quasiclassical Asymptotics of Malyuzhinets Functions

Multiresolution Analysis of ECG Signals in Heart Rhythm Monitoring

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