本セミナーは、Probability Victoria と共同で企画され、La Trobe University 理学部の Colloquium Series の一部である Statistics and Stochastic Seminar とも協力して開催します。セミナーは ハイブリッド形式 で行われます。La Trobe University Bundoora キャンパスでの 対面参加 と、Zoom でのオンライン参加 のどちらでも可能です。

興味がありそうな方がいれば、ぜひこの情報を共有してください。

日時	3月19日（木曜日）10:00 -11:00 AM (JST)
Zoom	https://unimelb.zoom.us/j/82915104880?pwd=fL1FgDhGLLQA7AH9aU1blQFj8s20ai.1
	Meeting ID: 82915104880	Passcode: 018576
講演者	Dr Olga Aryasova (Friedrich Schiller University, Jena, Germany)
タイトル	The hard membrane process and transport barriers of turbulent flows
概要	In confined fusion plasma devices such as tokamaks, turbulence is always present to some degree, and it has the undesirable effect of dispersing heat and particles from the central very hot and dense region to the boundary, and then to the surrounding areas and walls. Sometimes barriers arise in intermediate regions that reduce this dispersion. These barriers, also called zonal flows, are thin layers of plasma in which the fluid velocity is not turbulent, as it is elsewhere, but rather ordered, roughly laminar, and directed perpendicularly to the direction of dispersion. 　There is still active research aimed at understanding how these barriers arise, whether they can be triggered, how they evolve, and what their precise links are with other plasma dynamical features and parameters. Our aim here is to rigorously define a mathematical model of a sharp heat-diffusion barrier. In a scaling limit of the turbulence model with separation of scales, we obtain a heat equation with a space-dependent diffusion coefficient that diffuses poorly near the barrier. We then investigate the scaling limit in which the diffused barrier converges to a sharp separating surface, and describe the limit by means of the stochastic process known as Brownian motion with a hard membrane.

特に大学院生の方にとって，同じ数学でも分野が違う講演を聞く機会はあまり ないと思います．このセミナーは教員が非専門家向けに講演する貴重な機会です． 数理的な視野を広げる意味でも，英語に触れる意味でも，分野に関係なく気軽にご参加いただければと思います．また，意欲のある学部3年生，4年生の参加も大歓迎です．ふらっと覗いてみてください.

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