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Stiefel filters
Transactions of the Moscow Mathematical Society. 2024. Vol. 85. No. 2. P. 323–337.
A. Bogatyrev
The best uniform rational approximation of the Sign function on two intervals separated by zero was explicitly found by E. I. Zolotarëv in 1877. The natural extension of this problem to three bands was solved by E. Stiefel in 1961. We indicate the solutions overlooked by the prominent geometer and study their properties.
Bernardin C., Gonçalves P., Olla S., Mathematical Physics Analysis and Geometry 2024 Vol. 27 No. 7
We consider the macroscopic limit for the space-time density fluctuations in the open symmetric simple exclusion in the quasi-static scaling limit. We prove that the distribution of these fluctuations converge to a gaussian space-time field that is delta correlated in time but with long-range correlations in space. ...
Added: October 6, 2026
Bernardin C., Chhaibi R., Najnudel J. et al., Probability Theory and Related Fields 2026 Vol. 195 P. 1823–1875
We study the celebrated Shiryaev-Wonham filter (Wonham, W.M., in J. Soc. Ind. Appl. Math. 347–369, 1964) in its historical setup, where the hidden Markov jump process has two states. We are interested in the weak noise regime for the observation equation. Interestingly, this becomes a strong noise regime for the filtering equations. Earlier results of ...
Added: October 5, 2026
Ismailov A., Spiridonov V., Успехи математических наук 2026 Т. 81 № 5 С. 183–184
Получена новая формула для цепной дроби Аски–Вильсона в форме отношения двух q-гипер-геометрических рядов. ...
Added: October 5, 2026
Merzlinkin V., Khmelev A. V., Севрюков Д. О. et al., St. Petersburg Polytechnical University Journal: Physics and Mathematics 2025 No. 3 P. 205–209
Laser communication using satellites represents a promising avenue for data transmission in geographically distant areas without advanced infrastructure. This approach is characterized by its high transmission rate and low power requirements, providing substantial benefits over optical fiber and radio communication. However, the optical channel should exhibit greater transparency for light transmission, resulting in a severely restricted application of this technique for information ...
Added: October 5, 2026
Дуплинский А. В., Khmelev A. V., Бахшалиев Р. М. et al., St. Petersburg Polytechnical University Journal: Physics and Mathematics 2026 Vol. 17 No. 3 P. 88–92
Quantum key distribution via satellites enables the technology to be applied attranscontinental scale; nevertheless, in contrast to fiber systems, using a free-space opticalcommunication channel presents certain extra technological obstacles. The contribution of theacquisition, pointing and tracking system’s operation to the potential quantum bit error valueis investigated in this research. The polarization extinction ratio measurements varying ...
Added: October 5, 2026
Miller A., Pismeniuk L., Дуплинский А. В. et al., EPJ QUANTUM TECHNOLOGY 2023 Vol. 10 No. 1 P. 52–72
A satellite-constellation based global quantum network could allow secure quantum
communication between remote users worldwide. Such a constellation could be
formed of micro- or even nanosatellites, which have the advantage of being more
cost-effective than larger expensive spacecrafts. At the same time, the features of
quantum communication impose a number of technical requirements that are more
difficult to meet when ...
Added: October 5, 2026
Серебренников Д. А., Belov A. V., Информационные технологии и вычислительные системы 2026 № 3 С. 157–169
В условиях роста стоимости энергоресурсов и необходимости повышения энергоэффективности производственных процессов особую актуальность приобретает задача оптимизации энергопотребления промышленных предприятий. В данной работе рассматривается подход к управлению энергозатратами машиностроительного предприятия на основе методов многокритериальной оптимизации. Постановка задачи включает несколько целевых функций: минимизацию энергопотребления, минимизацию стоимости электроэнергии с учётом тарифных ограничений и максимизацию производственной эффективности. Для решения ...
Added: October 5, 2026
Korobok M., Хлыстунов М. Е., Шемолин И. С., Известия высших учебных заведений. Электроника 2026 Т. 31 № S4.3 С. 473–486
The paper considers the task of implementing the control law for mass-produced power supplies based on an LLC converter. The aim of the study is to create a control law that allows meeting the requirements for the stability of the converter at various parameters of the resonant circuit and the output filter.
For the feedback of ...
Added: October 4, 2026
Abdulkhaev K., Shirokov D., Advances in Applied Clifford Algebras 2026 Vol. 36 P. 1–21
In this paper, we present explicit formulas for the inverse and determinant in geometric (Clifford) algebras over vector spaces of dimension n = 7. The derivation of these formulas is made possible by generalizing the concept of conjugation to basis conjugation operations. We further develop a general method for constructing such formulas over odd-dimensional spaces ...
Added: October 4, 2026
Kuninets A., IEEE Transactions on Information Theory 2026 P. 1–1
In this work we study the applicability of Quasi-Cyclic Subfield Subcodes of Dual Elliptic (QC-SSDE) codes for integration into code-based cryptographic schemes. Detailed algorithms are provided for constructing parity-check matrices as well as block-circulant parity-check matrices for this family of codes, accompanied by empirical results that enable the construction of QC-SSDE codes with predetermined dimensions. ...
Added: October 3, 2026
Medvedev G., Alexandrov Artem, Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2026 Vol. 114 Article 044102
Graphons are measurable functions used to describe the asymptotic behavior of convergent graph families. Originally motivated by problems in combinatorics and graph theory, graphons have found numerous applications in the modeling and analysis of dynamical processes on networks. In this work, we use graphons to formulate the Ising model on convergent graph sequences, which include ...
Added: October 2, 2026
Pochinka O., Baranov D., Nozdrinova E., Теоретическая и математическая физика 2026 Т. 229 № 1 С. 3–14
The Birman–Williams problem on describing the planetary link of a fibered knot K in S^3 has been partially solved. Using Nielsen's theory for the classification of periodic surface homeomorphisms and its close relationship with the theory of gradient-like diffeomorphisms, it is proved that the planetary link of the trefoil (the unique periodic fibered knot of genus ...
Added: October 2, 2026
Lubashevsky I., Lubashevskiy V., Physica D: Nonlinear Phenomena 2026 Vol. 498 Article 135441
We develop a novel cloud-function formalism describing the dynamical relationship between sensory-information processing in large-scale brain networks (supraliminal processing) and the content of the mental representation of an observed object. The formalism combines elements of neural field theory for large-scale neural activity with the spatial characteristics of perceived objects and their embedding in the environment ...
Added: October 2, 2026
Zlotnik A., Математические заметки 2026 Т. 120 № 6 С. 1005–1009
Численным методам решения систем газодинамических уравнений посвящена обширная литература. Ранее было разработано и успешно апробировано специальное семейство симметричных по пространству консервативных разностных методов, основанных на предварительной кинетической, точнее, квазигазодинамической (КГД), регуляризации этих уравнений. Актуальной задачей является построение численных методов, которые обладают не только свойством консервативности по массе, импульсу и полной энергии, но и удовлетворяют условиям энтропийной ...
Added: October 1, 2026
Vyugin I. V., Sashadhar D., Algebra and Number Theory 2026 P. 1–10
We study the K-Fibonacci sequence Fp modulo prime p. Cardinalities of sets |Fp+Fp| and |Fp⋅Fp| are estimated. We present the method of estimating doubling constant of some m-dimensional recurrent sets in Fp. ...
Added: October 1, 2026
Kuksin S., Dynamical Systems 2026
We study the mixing properties of discrete-time and continuous-time dissipative dynamical systems driven by bounded mixing random forces. The continuous-time systems are
reduced to discrete-time random dynamical systems generated by time-one maps, so that
the main analysis is carried out in the discrete setting. We introduce a class of mixing random forcings whose regular conditional distributions with ...
Added: October 1, 2026
Kuksin S., Shirikyan A., Journal of Dynamics and Differential Equations 2026 P. 1098–1100
The paper deals with the problem of large-time behaviour of trajectories for discrete-time dynamical systems driven by a random noise. Assuming that the phase space is finite-dimensional and compact, and the noise is a Markov process with a transition probability satisfying some regularity hypotheses, we prove that all the trajectories converge to a unique measure ...
Added: October 1, 2026
Potanin B., Dolgikh S., Statistics and Probability Letters 2027 Article 110984
We derive bounds on the gradient and Hessian of the log-CDF, ln F(x), of the multivariate normal distribution. These bounds scale linearly and quadratically in ‖x‖ , respectively, with constants depending only on the covariance matrix. We demonstrate the usefulness of these bounds by proving asymptotic normality of the maximum-likelihood estimator of the multivariate probit ...
Added: October 1, 2026