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a network for developers and users of imaging and analysis tools
 

Thu 25 Jan 15:00: The future of governing equations

Other events - Sun, 21/01/2024 - 12:28
The future of governing equations

A major challenge in the study of dynamical systems is that of model discovery: turning data into reduced order models that are not just predictive, but provide insight into the nature of the underlying dynamical system that generated the data. We introduce a number of data-driven strategies for discovering nonlinear multiscale dynamical systems and their embeddings from data. We consider two canonical cases: (i) systems for which we have full measurements of the governing variables, and (ii) systems for which we have incomplete measurements. For systems with full state measurements, we show that the recent sparse identification of nonlinear dynamical systems (SINDy) method can discover governing equations with relatively little data and introduce a sampling method that allows SIN Dy to scale efficiently to problems with multiple time scales, noise and parametric dependencies. For systems with incomplete observations, we show that the Hankel alternative view of Koopman (HAVOK) method, based on time-delay embedding coordinates and the dynamic mode decomposition, can be used to obtain a linear models and Koopman invariant measurement systems that nearly perfectly captures the dynamics of nonlinear quasiperiodic systems. Neural networks are used in targeted ways to aid in the model reduction process. Together, these approaches provide a suite of mathematical strategies for reducing the data required to discover and model nonlinear multiscale systems.

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Mon 12 Feb 18:00: Going beyond emissions reduction – Climate Repair Check website for latest updates and booking information http://www.cambridgephilosophicalsociety.org

Talks - Thu, 18/01/2024 - 18:09
Going beyond emissions reduction – Climate Repair

The lecture will firstly summarise exactly where we are with climate change and crucially what the scientists are now considering in terms of the future. A future based purely on emissions reductions cannot keep the world below 1.5C.

We discuss some of the exciting ideas for greenhouse gas removal, and importantly going beyond terrestrial-based carbon dioxide removal. We will explore some of the approaches for marine carbon dioxide removal as well as the development of materials to accelerate the rate of oxidation of methane.

We will then spend time discussing what additional options we might have beyond emissions reduction and greenhouse gas removal; whilst these are necessary, even the most optimistic and ambitious scenarios considered by the IPCC indicate that they are not sufficient to keep temperatures below 1.5C. We will therefore review engineering concepts to limit temperature rise or interventions to protect glaciers and sea-ice, and ostensibly buy us time to stave off the worst effects of climate change whilst we get greenhouse gas levels down.

We will explore the different technologies which are being researched at the University of Cambridge in collaboration with multiple partner universities around the world, as well as the issues of public attitudes, governance and ethics associated with such research and potential deployment.

Check website for latest updates and booking information http://www.cambridgephilosophicalsociety.org

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Mon 29 Jan 18:00: G I TAYLOR LECTURE - The influence of GI Taylor: granular collapses, viscous gravity currents, explosive eruptions and chemical gardens Check website for latest updates and booking information http://www.cambridgephilosophicalsociety.org

Talks - Thu, 18/01/2024 - 18:06
G I TAYLOR LECTURE - The influence of GI Taylor: granular collapses, viscous gravity currents, explosive eruptions and chemical gardens

The presentation will start will a short summary of the seminal work of G. I. Taylor and his most famous student, G. K. Batchelor. Evaluations of the propagation of muti-sized granular material under a variety of conditions will then be described, as well as being illustrated with desk top experiments.

The lecture will then discuss the all important flow of viscous gravity currents, again illustrated by desk top experiments and actual photos and explanations of the recent eruption of the Soufriere of St. Vincent. A description of the development of chemical gardens will then be described, initially experimented upon by Johan Glauber, said to be the first chemical engineer, and then by Isaac Newton. It is said by some that chemical gardens are the origin of life, at deep-sea smokers, as will be described.

Check website for latest updates and booking information http://www.cambridgephilosophicalsociety.org

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Mon 26 Feb 18:00: The quest for the first stars and first black holes with the James Webb Space Telescope Check website for latest updates and booking information http://www.cambridgephilosophicalsociety.org

Talks - Thu, 18/01/2024 - 18:04
The quest for the first stars and first black holes with the James Webb Space Telescope

Finding and understanding the nature of the first stars at cosmic dawn is one of the most important and most ambitious goals for modern astrophysics. The first populations of stars produced the first chemical elements heavier than helium and formed the first, small protogalaxies, which then evolved, across the cosmic epoch, into the large and mature galaxies, such as the Milky Way and those in our local neighbour. Equally important and equally challenging is the search, in the early Universe, of the seeds of the first population of black holes, which later evolved in the supermassive black holes at the centre of galaxies, with masses even exceeding a billion times the mass of the Sun. When matter accretes on such supermassive black holes it can become so luminous to vastly outshine the light emitted by all stars in their host galaxy.

Since its launch, about two years ago, the James Webb Space Telescope has been revolutionizing this area of research. Its sensitivity in detecting infrared light from the remotest parts of the Universe is orders of magnitude higher than any previous observatory, an historical leap in astronomy and, more broadly, in science. I will presents some of the first, extraordinary discoveries from the Webb telescope, which have resulted in several unexpected findings. I will also discuss the new puzzles and areas of investigation that have been opened by Webb’s observations, how these challenge theoretical models, and the prospects of further progress in the coming years.

Check website for latest updates and booking information http://www.cambridgephilosophicalsociety.org

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Thu 18 Jan 15:00: Computing the Spectra and Pseudospectra of Band-Dominated and Random Operators

Talks - Thu, 11/01/2024 - 09:08
Computing the Spectra and Pseudospectra of Band-Dominated and Random Operators

I will give an overview of my work over the last 15 years, with collaborators including Marko Lindner (TU Hamburg), Ratchanikorn Chonchaiya (King Mongkut’s University of Technology, Bangkok), Raffael Hagger (Kiel), and Brian Davies (KCL), on computing the spectra and pseudospectra of banded and band-dominated operators. This will include describing algorithms that, given appropriate inputs, can produce a convergent sequence of approximations to the spectrum of an arbitrary band-dominated operator, with the property that each member of the sequence can be computed in finitely many arithmetical operations. We give a concrete implementation of the algorithm for operators that are pseudoergodic in the sense of Davies (Commun. Math. Phys. 2001) and illustrate this algorithm by spectral computations for the beautiful Feinberg-Zee random hopping matrix. Details can be found at https://arxiv.org/abs/2401.03984

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Thu 18 Jan 15:00: Computing the Spectra and Pseudospectra of Band-Dominated and Random Operators

Other events - Thu, 11/01/2024 - 09:08
Computing the Spectra and Pseudospectra of Band-Dominated and Random Operators

I will give an overview of my work over the last 15 years, with collaborators including Marko Lindner (TU Hamburg), Ratchanikorn Chonchaiya (King Mongkut’s University of Technology, Bangkok), Raffael Hagger (Kiel), and Brian Davies (KCL), on computing the spectra and pseudospectra of banded and band-dominated operators. This will include describing algorithms that, given appropriate inputs, can produce a convergent sequence of approximations to the spectrum of an arbitrary band-dominated operator, with the property that each member of the sequence can be computed in finitely many arithmetical operations. We give a concrete implementation of the algorithm for operators that are pseudoergodic in the sense of Davies (Commun. Math. Phys. 2001) and illustrate this algorithm by spectral computations for the beautiful Feinberg-Zee random hopping matrix. Details can be found at https://arxiv.org/abs/2401.03984

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Thu 14 Mar 15:00: TBA

Talks - Mon, 08/01/2024 - 11:01
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Thu 14 Mar 15:00: TBA

Other events - Mon, 08/01/2024 - 11:01
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Thu 07 Mar 15:00: TBA

Talks - Mon, 08/01/2024 - 10:58
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Thu 07 Mar 15:00: TBA

Other events - Mon, 08/01/2024 - 10:58
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Thu 29 Feb 15:00: TBA

Talks - Mon, 08/01/2024 - 10:55
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Thu 29 Feb 15:00: TBA

Other events - Mon, 08/01/2024 - 10:55
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Thu 22 Feb 15:00: TBA

Talks - Mon, 08/01/2024 - 10:53
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Thu 22 Feb 15:00: TBA

Other events - Mon, 08/01/2024 - 10:53
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Thu 15 Feb 15:00: TBA

Talks - Mon, 08/01/2024 - 10:52
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Thu 15 Feb 15:00: TBA

Other events - Mon, 08/01/2024 - 10:52
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Thu 01 Feb 15:00: TBA

Talks - Mon, 08/01/2024 - 10:51
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Thu 01 Feb 15:00: TBA

Other events - Mon, 08/01/2024 - 10:51
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Thu 25 Jan 15:00: TBA

Talks - Mon, 08/01/2024 - 10:50
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Thu 25 Jan 15:00: TBA

Other events - Mon, 08/01/2024 - 10:50
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