Персона:
Леонов, Александр Сергеевич

Организационные подразделения

Организационная единица

Институт общей профессиональной подготовки (ИОПП)

Миссией Института является: фундаментальная базовая подготовка студентов, необходимая для получения качественного образования на уровне требований международных стандартов; удовлетворение потребностей обучающихся в интеллектуальном, культурном, нравственном развитии и приобретении ими профессиональных знаний; формирование у студентов мотивации и умения учиться; профессиональная ориентация школьников и студентов в избранной области знаний, формирование способностей и навыков профессионального самоопределения и профессионального саморазвития. Основными целями и задачами Института являются: обеспечение высококачественной (фундаментальной) базовой подготовки студентов бакалавриата и специалитета; поддержка и развитие у студентов стремления к осознанному продолжению обучения в институтах (САЕ и др.) и на факультетах Университета; обеспечение преемственности образовательных программ общего среднего и высшего образования; обеспечение высокого качества довузовской подготовки учащихся Предуниверситария и школ-партнеров НИЯУ МИФИ за счет интеграции основного и дополнительного образования; учебно-методическое руководство общеобразовательными кафедрами Института, осуществляющими подготовку бакалавров и специалистов по социо-гуманитарным, общепрофессиональным и естественнонаучным дисциплинам, обеспечение единства требований к базовой подготовке студентов в рамках крупных научно-образовательных направлений (областей знаний).

Фамилия

Леонов

Имя

Александр Сергеевич

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Теперь показываю 1 - 10 из 32

Только метаданные
Fast Algorithm for Solving Some Three-Dimensional Inverse Problems of Magnetometry
(2024) Leonov, A. S.; Lukyanenko, D. V.; Yagola, A. G.; Леонов, Александр Сергеевич
Только метаданные
Numerical Solution of an Inverse Multifrequency Problem in Scalar Acoustics
(2020) Bakushinskii, A. B.; Leonov, A. S.; Леонов, Александр Сергеевич
© 2020, Pleiades Publishing, Ltd.Abstract: A new algorithm is proposed for solving a three-dimensional scalar inverse problem of acoustic sensing in an inhomogeneous medium with given complex wave field amplitudes measured outside the inhomogeneity region. In the case of data measured in a “plane layer,” the inverse problem is reduced via the Fourier transform to a set of one-dimensional Fredholm integral equations of the first kind. Next, the complex amplitude of the wave field is computed in the inhomogeneity region and the desired sonic velocity field is found in this region. When run on a moderate-performance personal computer (without parallelization), the algorithm takes several minutes to solve the inverse problem on rather fine three-dimensional grids. The accuracy of the algorithm is studied numerically as applied to test inverse problems at one and several frequencies simultaneously, and the stability of the algorithm with respect to data perturbations is analyzed.
Только метаданные
A New Algorithm for a Posteriori Error Estimation for Approximate Solutions of Linear Ill-Posed Problems
(2019) Leonov, A. S.; Леонов, Александр Сергеевич
A new algorithm for a posteriori estimation of the error in solutions to linear operator equations of the first kind in a Hilbert space is proposed and justified. The algorithm reduces the variational problem of a posteriori error estimation to two special problems of maximizing smooth functionals under smooth constraints. A finite-dimensional version of the algorithm is considered. The results of a numerical experiment concerning a posteriori error estimation for a typical inverse problem are presented. It is shown experimentally that the computation time required by the algorithm is less, on average, by a factor of 1.4 than in earlier proposed methods.
Только метаданные
Phase Modulations in a Speech Signal
(2022) Sorokin, V. N.; Leonov, A. S.; Леонов, Александр Сергеевич
© 2022, Pleiades Publishing, Ltd.Abstract: Mathematical models of the phase function and its parameters in speech-signal analysis problems have been investigated. The phase spectrum of a speech signal has been calculated using the Hilbert transform of signals at the output of a gammatone filterbank. Short- and long-term modulations of the linear phase component and phase derivatives with respect to frequency and time, and mixed derivative have been considered. The method for vowel segmentation using aggregation of the correlation coefficients of the phase parameters is described. Experiments on estimating the formant and pitch frequencies and the glottal opening and closure instants have been performed.
Только метаданные
Computing Magnifier for Refining the Position and Shape of Three-Dimensional Objects in Acoustic Sensing
(2022) Bakushinsky, A. B.; Leonov, A. S.; Леонов, Александр Сергеевич
Abstract: A computational procedure is proposed for refining the position and shape of three-dimensional acoustic inhomogeneities during the sound probing of a medium. The procedure, called a computing magnifier, is based on a high-speed algorithm for solving the inverse problem of acoustic sounding in areas of a special structure (three-dimensional space, cylindrical area, etc.) with a complex wave field amplitude as the data recorded in a thin layer. The algorithm was proposed and studied by the authors in their previous works. The computational magnifying procedure consists of quickly solving the inverse problem using this algorithm on the initial grid in the original 3D region, narrowing the original region to a nested smaller new region containing inhomogeneities, and then solving the inverse problem in this new region on a new grid with the same or even with fewer nodes. By repeating this procedure several times, we can significantly refine the position and shape of the studied inhomogeneities, as if enlarging them. The computational magnifying procedure works much faster than solving the inverse problem on adaptively refined 3D grids in the original area. This makes it easy to implement the procedure on personal computers (PCs) with average performance. A method for the numerical estimation of the quality of refining the position and shape of the studied inhomogeneities based on the use of histograms is proposed. A number of numerical model experiments on a PC on the use of a computing magnifier in a cylindrical region are presented. They include analysis of the quality of the position and shape of the refinement using histograms when solving an inverse problem with accurate and noisy data, the effect of averaging noisy data for determining the position and shape, experiments to assess the resolution of the computing magnifier, etc. The running time of the computing magnifier in each of these three-dimensional numerical experiments is about 10 s. © 2022, Pleiades Publishing, Ltd.
Только метаданные
ON THE PROPERTIES OF A FAST ALGORITHM FOR SOLVING A THREE-DIMENSIONAL INVERSE PROBLEM OF SCALAR ACOUSTICS
(2024) Bakushinsky, A. B.; Leonov, A. S.; Леонов, Александр Сергеевич
Только метаданные
Solution of the Inverse Elastography Problem in Three Dimensions for a Parametric Class with A Posteriori Error Estimation
(2019) Sharov, A. N.; Yagola, A. G.; Leonov, A. S.; Леонов, Александр Сергеевич
© 2019, Pleiades Publishing, Ltd.The paper presents the solution of a special three-dimensional inverse elastography problem: given a quasistatic model of a linear-elastic isotropic body subject to surface forces, to find the Young’s modulus distribution in the biological tissues under study using the known values of vertical displacements of these tissues. This study is aimed at detecting local inclusions in the tissue interpreted as tumors with values of the Young’s modulus that are significantly different from the known background. In addition, it is assumed that Young’s modulus is a constant function inside the unknown inclusions of a parametrically given geometry. This inverse problem leads to the solution of a nonlinear operator equation, which is reduced by a variational method to the extremum problem of finding the number of inclusions, parameters defining their shape, and the Young’s modulus for each inclusion. The problem is solved algorithmically by using a modification of the method of extending compacts by V. K. Ivanov and I. N. Dombrovskaya. To illustrate how the algorithm works, we give examples of solving model inverse problems with inclusions in the form of balls. A posteriori error estimation of the obtained distribution of Young’s modulus is carried out for the found solution to one of the model problems.
Только метаданные
Inverse problem for coefficients of equations describing propagation of COVID-19 epidemic
(2021) Leonov, A. S.; Nagornov, O. V.; Tyuflin, S. A.; Леонов, Александр Сергеевич; Нагорнов, Олег Викторович; Тюфлин, Сергей Александрович
© 2021 Institute of Physics Publishing. All rights reserved.The inverse problems for coefficients of ordinary differential equations describing propagation of coronavirus infection are studied. The well-known models of SEI and SEIR, and their generalization are used. Important role plays the coefficients of these equations that can be estimated by in-direct observations and depends on many factors. This approach allowed us to solve the problem with several waves of epidemic and to predict further propagation.
Только метаданные
Multifrequency Inverse Problem of Scalar Acoustics: Remarks on Nonuniqueness and Solution Algorithm
(2023) Bakushinsky, A. B.; Leonov, A. S.; Леонов, Александр Сергеевич
A three-dimensional multifrequency inverse problem of acoustic sounding of a stationary inhomogeneous medium is considered. This nonlinear inverse problem is reduced to solving an auxiliary three-dimensional linear Fredholm integral equation of the first kind. In the analysis of the uniqueness of the solution to the inverse problem, the connection between the integral equation and determining the source in the Helmholtz equation is indicated. The last problem is ambiguously solvable in the general case. Examples of such ambiguity are given. Questions about detailed data (frequencies, sources) ensuring or not the uniqueness of solutions are considered. A speed-efficient algorithm for solving the inverse problem based on Fourier transforms is proposed. This algorithm makes it possible to calculate uniquely an approximate solution by a stable method under data perturbations. The results of numerical experiments on solving a three-dimensional model inverse problem on fairly detailed grids are presented.
Только метаданные
Assessment of Tracks of Resonance Frequencies of the Vocal Tract
(2023) Leonov, A. S.; Sorokin, V. N.; Леонов, Александр Сергеевич