Mechanics Colloquium

 

PROGRAM

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MATEMATIČKI INSTITUT SANU
ODELJENJE ZA MEHANIKU

PROGRAM ZA OKTOBAR 2021.

 

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Predavanja se mogu pratiti na daljinu preko stranice:
https://miteam.mi.sanu.ac.rs/asset/YfY2cZTcN3YwGqFjc
Ukoliko želite da učestvujete u radu seminara ili da postavite pitanja na kraju predavanja, a još niste registrovani na miteam platformi Matematičkog instituta, možete se registrovati popunjavanjem forme:
https://miteam.mi.sanu.ac.rs/asset/o9cuDZYqrq7jvFxw8
Arhiva snimljenih predavanja se nalazi na stranici:
https://miteam.mi.sanu.ac.rs/asset/j9rAJJvBQHx2zgSSH

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Pozivamo Vas da učestvujete u radu sednica Odeljenja i to:

PETAK, 01.10.2021. u 14:15, On-line
Vladimir Dragović, Matematički instititut SANU & University of Texas, Dallas
ČEBIŠEVSKA DINAMIKA, IZOHARMONIJSKE DEFORMACIJE I INTEGRABILNI BILIJARI
U predavanju ćemo uvesti dinamiku Čebiševljevih polinoma na d realnih intervala i formulisati izomonodromna svojstva ovih dinamika. Objašnjavamo razliku između slučajeva dva i više od dva intervala. Koristeći injektivnost frekventnog bilijarskog preslikavanja, uvodimo izoharmonijske deformacije kao uopštenja Čebiševske dinamike. Dajemo eksplicitna rešenja pridruženih Šlezingerovih jednačina. Delovi rezultata su zajednički sa V. Šramčenko, a delovi sa M. Radnović.
Zajednička sednica sa Odeljenjem za matematiku.
Predavanje je u okviru jubileja 75 godina MISANU.

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SREDA, 06.10.2021. u 10:00, On-line
Teodor Atanacković, Srpska akademija nauka i umetnosti
TALASI U UOPŠTENOM ZENER-OVOM FRAKCIONOM MODELU
U radu se razmatra prostiranje talasa u jedno-dimenzionalnom modelu viskoelastičnog tela opisanog frakcionim Zener-ovim modelom. Ispituju se ograničenja na koeficijente modela koja slede iz uslova disipativnosti. Formulišu se uslovi za postojanje rešenja. Prikazana su i numerička rešenja problema za nekoliko vrednosti parametara.
Predavanje je u okviru jubileja 75 godina MISANU.

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SREDA, 06.10.2021. u 11:00, On-line
Milena Radnović, Matematički instititut SANU & University of Sidney
O ASIMPTOTICI PENELEVEOVIH TRANSCENDENTNIH FUNKCIJA
Koristeći konstrukciju prostora početnih vrednosti za Penleveove diferencijalne jednačine, pokazaćemo kako se može analizirati asimptotsko ponašanje rešenja tih jednačina u okolini singularnih tačaka. Ovo je zajednički rad s Nalini Joši.
Predavanje je u okviru jubileja 75 godina MISANU.

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SREDA, 06.10.2021. u 15:00, On-line
Srboljub Simić, Univerzitet u Novom Sadu
VARIATIONAL APPROACH TO MAXWELL-STEFAN MODEL OF DIFFUSION
Diffusion is the process motion of one specie relative to another. If the motion occurs relative to a background medium, the process is usually described by the Fick’s law or some of its generalizations. When the cross-diffusion is more prominent, like in gaseous mixtures the Maxwell-Stefan model is more appropriate. First aim of this lecture is to give an overview of different approaches to Maxwell-Stefan model of diffusion and recent mathematical results in this field. This will span phenomenological derivation of the model, kinetic theory approach to cross-diffusion models, and qualitative analysis of solutions of Maxwell-Stefan equations. Second aim is concerned with derivation of the Maxwell-Stefan model from the kinetic theory of mixtures. Crucial steps in this approach are scaling of the Boltzmann equations and assumption about the structure of velocity distribution functions. It will be shown that variational approach, based upon maximum entropy principle, in conjunction with proper scaling yields the velocity distribution functions in appropriate form and recovers Maxwell-Stefan equations. Moreover, entropy balance law will be derived with explicit form of entropy production rate.
Predavanje je u okviru jubileja 75 godina MISANU.

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SREDA, 06.10.2021. u 16:00, On-line
Alexey Bolsinov, Loughborough University
NIJENHUIS GEOMETRY
The purpose of the talk is to discuss new developments in Nijenhuis Geometry. Similar to Riemannian, Poisson or symplectic geometry, the Nijenhuis geometric structure is defined by means of a tensor of order 2 (i.e., by a matrix) but, in contrast to the above examples, this tensor is not a bilinear form but linear operator. The additional geometric condition imposed on this operator is that its Nijenhuis torsion identically vanishes. Open problems in this area include studying singular points of Nijenhuis operators, local normal forms, global properties and topological obstructions to the existence of such operators on closed manifolds.
Predavanje je u okviru jubileja 75 godina MISANU.

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SREDA, 27.10.2021. u 18:00, On-line
Teodor Vrećica, Scripps Institution of Oceanography, University of California, San Diego, USA
OBSERVATIONS OF STRONGLY MODULATED SURFACE WAVE AND WAVE BREAKING STATISTICS AT A SUBMESOSCALE FRONT
Ocean submesoscale currents, with spatial scales on the order 0.1 to 10 km, are horizontally divergent flows, leading to vertical motions that are crucial for modulating the fluxes of mass, momentum and energy between the air and sea, with important implications for biological and chemical processes. Recently, there has been considerable interest in the role of surface waves in modifying frontal dynamics. However, there is a severe lack of observations of these processes, which are needed to constrain and guide theoretical and numerical models. To this end, we present novel high resolution airborne remote sensing and in situ observations of wave-current interaction at a submesoscale front near the island of O’ahu, Hawaii. We find strong modulation of the surface wave field across the frontal boundary, including enhanced wave breaking, that leads to significant spatial inhomogeneities in the wave and wave breaking statistics. The non-breaking (i.e. Stokes) and breaking induced drifts are shown to be amplified at the boundary by approximately 50% and a factor of ten, respectively. The momentum flux from the wave field to the water column due to wave breaking is enhanced by an order of magnitude at the front. Using an orthogonal coordinate system that is tangent and normal to the front, we show that these sharp modulations occur over a distance of several meters in the direction normal to the front. Finally, we discuss these observations in the context of improved coupled models of air-sea interaction at a submesoscale front.

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Obavezno je nošenje maski i održavanje distance. Broj prisutnih na predavanju ograničen na najviše 10 (uključujući i predavača).

Predavanja su namenjena širokom krugu slušalaca, uključujući studente redovnih i doktorskih studija. Održavaju se sredom sa početkom u 18 sati u sali 301f na trećem spratu zgrade Matematičkog instituta SANU, Knez Mihailova 36.

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