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| Sep 24 |
Thu |
Abhishek Rajhans (Inter-University Center for Astronomy and Astrophysics (IUCAA), Pune, India) |
European Solar Physics Online Seminars (ESPOS) |
| 10:00 |
https://zoom.us/j/165498165 |
Forward modelling and energetics of Hi-C brightenings
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Abstract:
The Solar coronal heating problem remains a persistent challenge in astrophysics. Parker postulated back in 1988 that the heating of corona should be dominated by small energy dissipation events, referred to as nanoflares. However, there have not yet been any confirmed observations of individual nanoflares. Hi-C reported unique bright points with energies ranging between log[E(ergs)] = 24-25. Those brightenings were also identified in AIA passbands. Here, I will describe 0-D hydrodynamical simulations to forward model these tiny brightenings, study their energetics, and discuss possible implications for coronal heating.
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| Sep 24 |
Thu |
Abhishek Rajhans (Inter-University Centre for Astronomy and Astrophysics, IUCAA (IN)) |
SP2RC/ESPOS |
| 11:00 |
https://zoom.us/j/165498165 |
Forward modelling and energetics of Hi-C brightenings
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Abstract:
The Solar coronal heating problem remains a persistent challenge in astrophysics. Parker postulated back in 1988 that the heating of corona should be dominated by small energy dissipation events, referred to as nanoflares. However, there have not yet been any confirmed observations of individual nanoflares. Hi-C reported unique bright points with energies ranging between log[E(ergs)] = 24-25. Those brightenings were also identified in AIA passbands. Here, I will describe 0-D hydrodynamical simulations to forward model these tiny brightenings, study their energetics, and discuss possible implications for coronal heating.
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| Sep 30 |
Wed |
Visakan Balakumar (Sheffield) |
Cosmology, Relativity and Gravitation |
| 15:00 |
Blackboard Collaborate |
Quantum superradiance on static black hole space-times
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Abstract:
We study the quantum analogue of the classical process of superradiance for a massless charged scalar field on a charged black hole space-time. We show that an “in” vacuum state, which is devoid of particles at past null infinity, contains an outgoing flux of particles at future null infinity. This radiation is emitted in the superradiant modes only, and is nonthermal in nature.
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| Oct 1 |
Thu |
Rekha Jain (Sheffield) |
Plasma Dynamics Group |
| 16:00 |
https://meet.google.com/chc-nxsh-xcz |
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| Oct 2 |
Fri |
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SP2RC seminar |
| 13:00 |
LT 11 |
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| Oct 7 |
Wed |
Katy Clough (Oxford) |
Cosmology, Relativity and Gravitation |
| 15:00 |
remote |
TBA |
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| Oct 8 |
Thu |
(Physikalisch-Meteorologisches Observatorium Davos, PMOD/WRC (CH)) |
SP2RC/ESPOS |
| 00:00 |
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| Oct 14 |
Wed |
Indira Chatterji (University of Nice) |
Pure Maths Colloquium |
| 14:00 |
online |
Group ring conjectures and relative hyperbolicity
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Abstract:
The idempotent conjecture is that there should be no idempotent in the group ring of a torsion-free group. I will discuss this conjecture, as well as associated conjectures in some geometric context, and will use them as an excuse to discuss hyperbolicity and introduce relative hyperbolicity, a context in which some of these conjectures are still open.
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| Oct 14 |
Wed |
Jose Cembranos (Madrid) |
Cosmology, Relativity and Gravitation |
| 15:00 |
remote |
TBA |
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| Oct 15 |
Thu |
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SP2RC seminar |
| 10:00 |
LT 11 |
UK Solar Online Seminar Series (UK-SOSS) monthly seminar:
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| Oct 15 |
Thu |
George Haller (ETH Zurich (Switzerland)) |
Plasma Dynamics Group |
| 13:00 |
https://meet.google.com/zxj-ofaw-guc |
Objective material barriers to the transport of momentum and vorticity
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Abstract:
I discuss a recent theory for material surfaces that maximally inhibit
the diffusive transport of a dynamically active (i.e.,
velocity-dependent) vector field, such as the linear momentum, the
angular momentum or the vorticity, in three-dimensional unsteady flows.
These diffusion barriers provide physics-based, observer-independent
boundaries of dynamically active coherent structures. Instantaneous
limits of these Lagrangian diffusion barriers mark objective Eulerian
barriers to short-term active transport. I show how active diffusion
barriers can be identified with active versions of Lagrangian coherent
structure (LCS) diagnostics. In comparison to their passive
counterparts, however, active LCS diagnostics require no significant
fluid particle separation and hence provide substantially
higher-resolved Lagrangian and Eulerian coherent structure boundaries
from shorter velocity data sets. I illustrate these results on
two-dimensional turbulence and three-dimensional wall-bounded turbulence.
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| Oct 21 |
Wed |
Atsushi Higuchi (York) |
Cosmology, Relativity and Gravitation |
| 15:00 |
remote |
TBA
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| Oct 22 |
Thu |
(University of Coimbra (PT)) |
SP2RC/ESPOS |
| 00:00 |
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| Oct 28 |
Wed |
Clara Loeh (University of Regensburg) |
Pure Maths Colloquium |
| 14:00 |
J11 |
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| Oct 28 |
Wed |
Harry Desmond (Oxford) |
Cosmology, Relativity and Gravitation |
| 15:00 |
remote |
TBA |
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| Nov 4 |
Wed |
Ulrich Pennig (University of Cardiff) |
Pure Maths Colloquium |
| 14:00 |
J11 |
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| Nov 5 |
Thu |
(Institut d’Astrophysique Spatiale, IAS (FR)) |
SP2RC/ESPOS |
| 00:00 |
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| Nov 11 |
Wed |
Sira Gratz (University of Glasgow) |
Pure Maths Colloquium |
| 14:00 |
J11 |
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| Nov 11 |
Wed |
Lisa Glaser (Vienna) |
Cosmology, Relativity and Gravitation |
| 15:00 |
remote |
TBA
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| Nov 12 |
Thu |
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SP2RC seminar |
| 10:00 |
LT 11 |
UK Solar Online Seminar Series (UK-SOSS) monthly seminar: |
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| Nov 12 |
Thu |
Francisco Guzman (Universidad Michoacana de San Nicolas de Hidalgo, Mexico) |
Plasma Dynamics Group |
| 16:00 |
Remote |
TBA
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Abstract:
TBA
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| Nov 18 |
Wed |
Andreagiovanni Reina (CS, Sheffield) |
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| 14:00 |
https://meet.google.com/??? |
Collective Decision Making: From Bees to Robots via Multiscale Modelling
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Abstract:
I will give an overview of my studies on modelling and simulating collective decision making in distributed systems. Such systems, found in biology, sociology, and engineering, are composed of a large number of interacting individuals that coordinate in order to reach a consensus. The main phases of the collective decision making process consist of identifying the available options, estimating their quality, and selecting the best option or any of them. I will present the main results of my research in understanding and designing each of these phases. Collective systems are inherently difficult to analyse as the stochastic nonlinear interactions between individuals can give rise to complex emergent dynamics. Therefore, I employ a collection of advanced techniques, commonly defined as multiscale modelling. Relying on a set of methods, rather than a single one, gives the benefit of having complementary techniques addressing one another's limitations. In fact, through multiscale modelling, it is possible to analyse the systems at various levels of complexity and detail, from macroscopic group-level dynamics to microscopic individual-level behaviour, and from noise-free deterministic models to stochastic spatial descriptions. I finally shed a light on the recently developed opensource software for automated multiscale modelling. This software, called MuMoT, can also be a useful resource for remote teaching. For more info on MuMoT see (Marshall et al. PlosOne 2019) or MuMoT live notebook (https://mumot.readthedocs.io/).
Bio:
Dr Andreagiovanni Reina is a Research Fellow in Collective Robotics at the University of Sheffield, UK. He is currently working on the DiODe project (Distributed Algorithms for Optimal Decision-Making) led by Prof. James Marshall, and is the Principal Investigator of the Swarm Awareness project (https://swarmawareness.group.shef.ac.uk/). Andreagiovanni is the researcher responsible for more than 900 Kilobot robots and the related Augmented Reality for Kilobot (ARK) infrastructure at Sheffield Robotics. He holds a PhD in applied sciences from IRIDIA (Marco Dorigo's AI-Laboratory) of the Université Libre de Bruxelles, Belgium, and an M.Sc. in computer engineering from Politecnico di Milano, Italy. He has been a researcher in five European projects on distributed robotic systems since 2009. In December 2020, he plans to return to Brussels with an FNRS Fellowship on modelling heterogeneity in decentralised consensus. Full info at http://areina.staff.shef.ac.uk.
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| Nov 18 |
Wed |
Sara Arias de Reyna (University of Seville) |
Pure Maths Colloquium |
| 14:00 |
J11 |
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| Nov 18 |
Wed |
Andreagiovanni Reina (CS, Sheffield) |
Applied Mathematics Colloquium |
| 14:00 |
https://meet.google.com//kkc-jmys-uwa |
Collective Decision Making: From Bees to Robots via Multiscale Modelling
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| |
| |
Abstract:
Abstract:
I will give an overview of my studies on modelling and simulating collective decision making in distributed systems. Such systems, found in biology, sociology, and engineering, are composed of a large number of interacting individuals that coordinate in order to reach a consensus. The main phases of the collective decision making process consist of identifying the available options, estimating their quality, and selecting the best option or any of them. I will present the main results of my research in understanding and designing each of these phases. Collective systems are inherently difficult to analyse as the stochastic nonlinear interactions between individuals can give rise to complex emergent dynamics. Therefore, I employ a collection of advanced techniques, commonly defined as multiscale modelling. Relying on a set of methods, rather than a single one, gives the benefit of having complementary techniques addressing one another's limitations. In fact, through multiscale modelling, it is possible to analyse the systems at various levels of complexity and detail, from macroscopic group-level dynamics to microscopic individual-level behaviour, and from noise-free deterministic models to stochastic spatial descriptions. I finally shed a light on the recently developed opensource software for automated multiscale modelling. This software, called MuMoT, can also be a useful resource for remote teaching. For more info on MuMoT see (Marshall et al. PlosOne 2019) or MuMoT live notebook (https://mumot.readthedocs.io/).
Bio:
Dr Andreagiovanni Reina is a Research Fellow in Collective Robotics at the University of Sheffield, UK. He is currently working on the DiODe project (Distributed Algorithms for Optimal Decision-Making) led by Prof. James Marshall, and is the Principal Investigator of the Swarm Awareness project (https://swarmawareness.group.shef.ac.uk/). Andreagiovanni is the researcher responsible for more than 900 Kilobot robots and the related Augmented Reality for Kilobot (ARK) infrastructure at Sheffield Robotics. He holds a PhD in applied sciences from IRIDIA (Marco Dorigo's AI-Laboratory) of the Université Libre de Bruxelles, Belgium, and an M.Sc. in computer engineering from Politecnico di Milano, Italy. He has been a researcher in five European projects on distributed robotic systems since 2009. In December 2020, he plans to return to Brussels with an FNRS Fellowship on modelling heterogeneity in decentralised consensus. Full info at http://areina.staff.shef.ac.uk.
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| Nov 19 |
Thu |
(Queen’s University Belfast, Astrophysics Research Centre (UK)) |
SP2RC/ESPOS |
| 00:00 |
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| Nov 25 |
Wed |
Ailsa Keating (University of Cambridge) |
Pure Maths Colloquium |
| 14:00 |
J11 |
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| Dec 2 |
Wed |
Yemon Choi (University of Lancaster) |
Pure Maths Colloquium |
| 14:00 |
J11 |
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| Dec 3 |
Thu |
(Leibniz Institute for Astrophysics Potsdam (DE)) |
SP2RC/ESPOS |
| 00:00 |
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| Dec 9 |
Wed |
Kathryn Hess (École Polytechnique Fédérale de Lausanne) |
Pure Maths Colloquium |
| 14:00 |
J11 |
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| Dec 10 |
Thu |
|
SP2RC seminar |
| 10:00 |
LT 11 |
UK Solar Online Seminar Series (UK-SOSS) monthly seminar: |
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| Dec 10 |
Thu |
Richard Morton (University of Northumbria) |
Plasma Dynamics Group |
| 16:00 |
|
TBA
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Abstract:
TBA
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| Dec 16 |
Wed |
Marina Illiopoulou (University of Kent) |
Pure Maths Colloquium |
| 14:00 |
J11 |
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| Dec 17 |
Thu |
(University of Sheffield, Solar Physics and Space Plasma Research Centre (UK)) |
SP2RC/ESPOS |
| 00:00 |
|
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| Jan 21 |
Thu |
|
SP2RC seminar |
| 13:00 |
LT 11 |
UK Solar Online Seminar Series (UK-SOSS) monthly seminar: |
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