Proceedings of Journees 2019

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Proceedings of Journees 2019

Paris Observatory, 2020.

Bizouard C.

Journees 2019 have been marked by record numbers of participants and communications. Therewere 118 attendants coming from 21 countries over the 5 continents. The scientific programincluded 58 oral presentations and 38 posters. Presentations were split into five sessions, alternatingastrometry (sessions I and III), Earth rotation changes (Session II/IV) and solar system dynamics(session V). Of particular interest were the communications dedicated to the results of the Gaiamission and its possible future prolongation in IR band (Session I), the realization of the InternationalCelestial Frame III (session III). In session II, many interesting talks were devoted to the centennialof the ”Earth rotation” IAU commission

On the variability of the Chandler wobble

Zotov L., Bizouard C., Сидоренков Н. С. et al., , in: Proceedings of Journees 2019.: Paris Observatory, 2020. P. 249–254.

The works that we carried out during the last ten years lead to significant progress inthe knowledge of the Chandler wobble (CW) of the Earth polar motion (PM). In Zotov and Bizouard(2012) we reconstructed the excitation of this resonant mode by using Panteleev’s correctivefiltering. Now we are sure, that this filtering is a regularizing algorithm ...

Added: November 30, 2020

Decadal fluctuations in Earth’s rotationas evidences of lithospheric drift over the asthenospere

Сидоренков Н. С., Dionis E., Bizouard C. et al., , in: Proceedings of Journees 2019.: Paris Observatory, 2020. P. 243–247.

The decadal instabilities in Earth’s rotation (DIER) are thought to be caused bythe interactions between the Earth’s core and its mantle. This hypothesissuccessfully explains whythere is a close correlation between DIER and the variations in the rate of the westward drift of thegeomagnetic eccentric dipole, since it is successfully reproduced by modeling of the redistribution ...

Added: November 30, 2020

Priority areas: mathematics

Language: English

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Infinitely many graph manifolds with unique geometrical piece that admit arbitrarily many Anosov flows

Pochinka O., Shmukler V., / Series math.RT "arXiv:1808.06395 [math.RT]". 2026.

Anosov flows have a long and rich history, firstly motivated by the study of geodesic flows in negative curvature surface by Anosov and Sinai. Not every closed manifold admits an Anosov flow for well-known reasons: the fundamental group of a 3-manifold M admitting an Anosov flow must have exponential growth, and M must be universally covered by R3. Nevertheless, there ...

Added: August 31, 2026

New bound on S1× S2-setting Bell locality of a nonseparable Werner state

Loubenets E. R., / Series arxiv.org "quant-ph". 2026. No. 2607.18050.

In many quantum applications it is important to know whether or not a Bell nonlocal two-qudit state exhibits its nonlocality under correlation scenarios with some given numbers S1,S2≥1 of generalized quantum measurements at two sites. In the present article, we find analytically a new general locality condition sufficient for a nonseparable Werner state with a ...

Added: July 21, 2026

On functional equations for Chow polylogarithms

Bolbachan V., / Series math "arxiv.org". 2024.

Chow polylogarithms are some special functions arising in explicit description of the Beilinson regulator map. The most interesting functional equation for this function reflects its vanishing on the boundary in the Bloch's cycle complex. We show that this functional equation formally follows from more simple ones, namely skew-symmetry, functoriality and multiplicativity. To prove this, we study ...

Added: July 16, 2026

On Goncharov’s conjecture in next to Milnor degree

Bolbachan V., / Series math "arxiv.org". 2024.

Let K be a field of characteristic zero. We prove that its motivic cohomology in degree m−1 and weight m is rationally isomorphic to the cohomology of the polylogarithmic complex. This gives a partial extension of A. Suslin theorem describing the indecomposable K3 of a field. ...

Added: July 16, 2026

Statistical inference based on band-limited kernels: Rational-infinitely divisible distributions and beyond

Panov V., Ryabchenko A., / Series arXiv "stat.ME". 2026. No. 2607.05048.

This paper investigates the problem of statistical inference for a mixture distribution consisting of a discrete and a continuous component, with a particular focus on the class of rational-infinitely divisible distributions. We consider non-parametric estimation of both components of the mixture as well as the quasi-L{é}vy measure, assuming that the mixture belongs to the class ...

Added: July 9, 2026

Strong Approximations for Markov Chains Weakly Converging to Diffusions

Konakov V., Kucher D., Mammen E., / Series arXiv "math". 2026. No. 2606.11142v1.

In this paper, we construct strong approximations for discrete-time Markov chains weakly converging to continuous diffusion processes, as well as for their perturbed counterparts. Under the assumption of bounded coefficients, we construct closely coupled versions of these processes on a shared probability space. In particular, for both non-degenerate and degenerate cases, we maximize the probability ...

Added: June 11, 2026

Bifurcations and Structural Stability of Generic PC-HC Families

Dorovskiy A., / Series arXiv "math". 2026.

In this paper the structural stability of generic families of vector fields of the PC-HC class on the two-dimensional sphere is proved. A classification of these families up to moderate equivalence in neighborhoods of their large bifurcation supports is presented, based on such invariants as the configuration and the characteristic set. The realization lemma is proved. ...

Added: May 14, 2026

On the minimum number of maximal distance-k independent sets in trees

Taletskii D., / Series arXiv "math". 2026.

A vertex subset of a graph is called a \textit{distance-$k$ independent set} if the distance between any two of its distinct vertices is at least $k + 1$. For all $n,k \geq 1$, we determine the minimum possible number of inclusion-wise maximal distance-$k$ independent sets among all $n$-vertex trees. It equals~$n$ if $n \leq k ...

Added: May 1, 2026

On Arithmetic Mirror Symmetry for smooth Fano fourfolds

Ovcharenko M., / Series arXiv "math". 2026.

We introduce an explicit class of tempered Laurent polynomials in the sense of Villegas and Doran--Kerr in n⩽4 variables including all Landau--Ginzburg models for smooth Fano threefolds with very ample anticanonical class. We check that it contains Landau--Ginzburg models for various Fano fourfolds which are complete intersections in smooth toric varieties and Grassmannians of planes, ...

Added: April 30, 2026

On weak solutions to the 1d compressible Navier-Stokes equations: a Lipschitz continuous dependence on data in weaker norms and an error of their homogenization

Zlotnik Alexander, / Series arXiv "math". 2026. No. 2602.03481v1.

We deal with the global in time weak solutions to the 1D compressible Navier-Stokes system of equations for large discontinuous initial data and nonhomogeneous boundary conditions of three standard types. We prove the Lipschitz-type continuous dependence of the solution $(\eta,u,\theta)$, in a norm slightly stronger than $L^{2,\infty}(Q)\times L^2(Q)\times L^2(Q)$, on the initial data $(\eta^0,u^0,e^0)$ in a ...

Added: April 18, 2026

On the dimension of the space of static potentials on three-manifolds

Medvedev V., / Series arXiv "math". 2026.

We investigate the interplay between the dimension of the space of static potentials and the geometric and topological structure of the underlying static three-manifold. A partial classification of boundaryless static manifolds is obtained in terms of this dimension. We also treat the case of static manifolds with boundary. In particular, we prove that if a ...

Added: April 3, 2026

Using predefined vector systems to speed up neural network multimillion class classification

Gabdullin N., Androsov I., / Series Computer Science "arxiv.org". 2026.

Label prediction in neural networks (NNs) has O(n) complexity proportional to the number of classes. This holds true for classification using fully connected layers and cosine similarity with some set of class prototypes. In this paper we show that if NN latent space (LS) geometry is known and possesses specific properties, label prediction complexity can ...

Added: April 2, 2026

Chandler Wobble and LOD Anomalyes in 2010–2020s

Zotov L., Sidorenkov N., Bizouard C., , in: Proceedings of the 19th Annual Meeting ofthe Asia Oceania Geosciences Society.: Singapore: World Scientific Publishing Co. Pte. Ltd, 2023. P. 153–155.

In early 2000-s the amplitude of the Chandler wobble (CW) started to decrease and in 2017-2020 reached its historic minima, comparable only with the minima of ~1928 yr. In 2021 the CW appeared again. We demonstrate that the phase of the CW is changing now, as during 1920-1930s. Since 2010 it has changed almost by ...

Added: March 5, 2026

Earth Rotation Variations and the Moon Apsidal-Nodal Effects

Zotov L., Sidorenkov N., Bizouard C., , in: Proceedings of the XV Conference and School (St. Petersburg, Russia, April 22–26). Problems of Geocosmos—2024.: Switzerland: Springer, 2026. P. 289–312.

Earth rotation in recent epoch shows anomalies: its rotation velocity reached decadal maximum in 2024; the Chandler wobble (CW) of the rotation axis disappeared in 2018–2020, then resumed with a phase changed by 180^\circ ◦; the ampli-tude of the Free Core Nutation (FCO) decreased since 2021 as well. We analyzed the CW amplitude modulations since the ...

Added: March 1, 2026

Homogeneous maximizers of the Blaschke-Santalo-type functionals

Kolesnikov A., / Series arXiv "math". 2025.

We study Blaschke--Santal{ó}-type inequalities for N>=2 sets (functions) and a special class of cost functions. In particular, we prove new results about reduction of the maximization problem for the Blaschke--Santal{ó}-type functional to homogeneous case (functional inequalities on the sphere) and extend the symmetrization argument to the case of N>2 sets. We also discuss links to the ...

Added: February 13, 2026

Iterative Ricci-Foster Curvature Flow with GMM-Based Edge Pruning: A Novel Approach to Community Detection

Sorokin K., Beketov M., Онучин А. et al., / arxiv.org. Серия cs.SI "Social and Information Networks ". 2025.

Community detection in complex networks is a fundamental problem, open to new approaches in various scientific settings. We introduce a novel community detection method, based on Ricci flow on graphs. Our technique iteratively updates edge weights (their metric lengths) according to their (combinatorial) Foster version of Ricci curvature computed from effective resistance distance between the ...

Added: January 15, 2026

On finding formal power-logarithmic expansions of solutions to q-difference equations

Gaianov N., Parusnikova A., / Cornell University. Серия math "arxiv.org". 2025.

An algebraic q-difference equation is considered. A sufficient condition for the existence of a formal power-logarithmic expansion of a solution to such an equation in the neighborhood of zero is proposed. An example of applying this sufficient condition for constructing a formal expansion of a solution to a certain q-difference analogue of the fifth Painlevé equation ...

Added: December 25, 2025

Ideal of the variety of flexes of plane cubics

Popov V., / Series arXiv "math". 2025. No. 2502.01539.

We prove that the variety of flexes of algebraic curves of degree 3 in the projective plane is an ideal theoretic complete intersection in the product of a two-dimensional and a nine-dimensional projective spaces. ...

Added: December 16, 2025

Фильтр Калмана с полосовой частотной фильтрацией для выделения Чандлеровского колебания полюса.

Zotov L., Логинов А. В., Ольховский А. А. et al., В кн.: ВОПРОСЫ ТЕОРИИ И ПРАКТИКИ ГЕОЛОГИЧЕСКОЙ ИНТЕРПРЕТАЦИИ ГРАВИТАЦИОННЫХ, МАГНИТНЫХ И ЭЛЕКТРИЧЕСКИХ ПОЛЕЙ 51-я сессия Международного семинара им. Д.Г. Успенского - В.Н. Страхова. Москва, 2025.: Пермский государственный университет, 2025.

One of the major components of the Earth’s polar motion is Chandler wobble with 433-day period. To extract it from observations narrow-band filtering is required. We have developed method which joins Kalman filtering and band-pass filtering in direct time with the phase correction in reversed time. By using Euler-Liouville equation generating resonant CW as a ...

Added: December 10, 2025

GRACE & GFO SATELLITE GRAVIMETRY DATA FOR HYDROLOGY AND EARTH ROTATION

Zotov L., Юшкин В. Д., Фролова Н. Л. et al., , in: Информационные технологии и нанотехнологии (ИТНТ-2024). сборник трудов по материалам X Международной конференции и молодежной школы: в 6 томах.: Самарский государственный университет, 2024. P. 22002–22004.

The GRACE and GRACE-FO satellites provide data on the Earth's gravitational field changes and are among the most successful NASA/DLR geodetic missions in recent decades. Based on their data, the melting of glaciers, redistribution of masses in the river basins, and changes in the ocean mass are studied. We use multichannel singular spectral analysis (MSSA) ...

Added: May 30, 2025

Analytical Fluid Dynamics in Lagrangian Variables

Abrashkin A. A., World Scientific Publishing Co. Pte. Ltd, 2025.

This book is devoted to the problems of the analytical description of incompressible fluid flows in Lagrangian variables. Commonly, specialists in fluid dynamics prefer to use the Euler approach. For example, even classical textbooks by J. Batchelor, L.G. Loitsyansky, L.D. Landau, and E.M. Lifshitz do not provide the Lagrange equations of f luid dynamics. Exceptions ...

Added: January 28, 2025

ОСОБЕННОСТИ ВРАЩЕНИЯ ЗЕМЛИ И ЭЛЬ-НИНЬО ЮЖНОГО КОЛЕБАНИЯ В 2020-Е ГОДЫ

Zotov L., Сидоренков Н. С., Марчукова О. В. et al., В кн.: ВОПРОСЫ ТЕОРИИ И ПРАКТИКИ ГЕОЛОГИЧЕСКОЙ ИНТЕРПРЕТАЦИИ ГРАВИТАЦИОННЫХ, МАГНИТНЫХ И ЭЛЕКТРИЧЕСКИХ ПОЛЕЙ 50-я юбилейная сессия Международного семинара им. Д.Г. Успенского - В.Н. Страхова. Москва, 2024.: М.: Издательство "Перо", 2024. С. 162–166.

Since strong El Nino 2016 the tendency of acceleration of the Earth rotation has been observed. In 2022 the Earth rotation velocity reached maxima comparable with those happened 90 years ago. Triplet of La Nina accompanied this case. Chandler wobble of the pole almost disappeared in 2017-2020, which was earlier observed only in the end ...

Added: March 1, 2024

Anomalies in the Earth rotation and Syzygies in Perigee

Zotov L., Industry 4.0 2023 Vol. 8 No. 5 P. 166–168

In 2022 the Erath rotation velocity reached its maximum and in 2017-2020 the Chandler wobble of the rotational axis disappeared for the second time in the history of observations. Unexplained modulations of 90 and 20-25 year periods are observed. They reflect geophysical processes in the atmosphere, ocean, and Earth’s interior and can be linked to ...

Added: February 10, 2024

Аномалии чандлеровского колебания полюса в 2010-е годы

Zotov L., Сидоренков Н. С., Бизуар К., Вестник Московского университета. Серия 3: Физика и астрономия 2022 № 3 С. 64–72

The Earth’s rotation is nonuniform: the position of the pole drifts and describes circles with the annual and Chandler (433 days) periods; the Earth’s rotation velocity also varies. In the beginning of 2000s, the amplitude of the Chandler wobble began to decrease and in 2017–2020 reached a historical low comparable only with the low of ...

Added: October 25, 2022