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Events - Page 3

Time and place: , Abels Utsikt (NHA 1259)
Time and place: , Auditorium 1, Vilhelm Bjerknes hus, Blindern

We invite you to a two day seminar celebrating Nils Lid Hjort's significant and extensive contributions in statistics.

Time and place: , Niels Henrik Abels hus, 9th floor

A peculiarity of nonlinear hyperbolic problems is that they must be interpreted as limits of second-order equations with vanishing viscosity. Despite not explicitly being present in the hyperbolic case, diffusion is needed, e. g., at discontinuities or to avoid the occurrence of nonphysical states. In the case of gas dynamics, for instance, dissipation corresponds to the production of thermodynamic entropy. To solve hyperbolic problems numerically, one needs to adapt these ideas to the discrete setting. Standard high-order methods, however, do not incorporate the appropriate amounts of artificial viscosity because these need to be chosen adaptively based on the solution. Among the high-resolution schemes capable of doing so are the recently proposed monolithic convex limiting (MCL) techniques [1] to be discussed in this talk. They offer a way to enforce physical admissibility, entropy stability, and discrete maximum principles for conservation laws. These methods can also be generalized to systems of balance laws in a well-balanced manner [2]. In addition to second-order finite element methods, extensions to high-order discontinuous Galerkin (DG) schemes shall also be presented [3]. Numerical examples for the so-called KPP problem, the nonconservative shallow water system, and the compressible Euler equations will be shown. An overview of MCL and other property-preserving methods can be found in our recently published book [4].

Time and place: , NHA 723 and Online
Time and place: , NHA B1120

We prove that (logarithmic, Nygaard completed) prismatic and (logarithmic) syntomic cohomology are representable in the category of logarithmic motives. As an application, we immediately obtain Gysin maps for prismatic and syntomic cohomology, and we precisely identify their cofibers. In the second part of the talk we develop a descent technique that we call saturated descent, inspired by the work of Niziol on log K-theory. Using this, we prove crystalline comparison theorems for log prismatic cohomology, log Segal conjectures and log analogues of the Breuil-Kisin prismatic cohomology, from which we get Gysin maps for the Ainf cohomology.

Time and place: , room 1259 (Abels Utsikt) - Niels Henrik Abels hus

Doctoral candidate Thea Josefine Ellevold at the Department of Mathematics will be defending the thesis
Numerical investigations of internal solitary waves: the evolution of instability in the bottom boundary layer and the wave-vortex-induced particle motion for the degree of Philosophiae Doctor .

Time and place: , room 1259 (Abels Utsikt) - Niels Henrik Abels hus

Doctoral candidate Lucas Yudi Hataishi at the Department of Mathematics will be defending the thesis Quantum symmetries implemented by quantum groups and unitary tensor categories for the degree of Philosophiae Doctor .

Time and place: , Tøyen Hovedgård

On November 21-23 the Integreat team and partners convened for the first-ever kick-off meeting at the historic Tøyen Hovedgård in Oslo. The event marked a crucial milestone for the Integreat community and served as an opportunity to articulate common goals, define the purpose of upcoming projects, and facilitate team building.

Time and place: , Erling Sverdrups plass, Niels Henrik Abels hus, 8th floor
This paper considers hypothesis testing in semiparametric models which may be non – regular for certain values of a (potentially infinite dimensional) nuisance parameter. In such models no (locally) regular estimator of the parameter of interest exists. The situation for testing is somewhat different: I establish that C(α) – style test statistics achieve their limiting distributions in a (locally) regular manner under mild conditions, leading to tests with correct size in situations where standard tests fail to control size. Additionally, I characterise the appropriate limit experiment in which to study local (asymptotic) optimality of tests in the case where the efficient information matrix is singular. This permits the generalisation of classical power bounds to the non – regular case. I provide appropriate statements of these bounds and give conditions under which they are attained by the proposed C(α) – style tests. Three examples are worked out in detail.
Time and place: , Niels Henrik Abels hus, 9th floor

We combine a pressure correction scheme with interior penalty discontinuous Galerkin (dG) discretisation to solve the time-dependent Navier–Stokes equations. We prove unconditional energy stability and a priori error estimates for the velocity. With duality arguments, optimal L2 error rates are obtained. Convergence of the discrete pressure is also established.  Further, we propose a splitting scheme,  integrating the pressure correction approach, for the Cahn–Hilliard–Navier–Stokes system  The numerical analysis of dG combined with this scheme is discussed. Namely, we show well--posedness, stability, and error estimates. Numerical results with manufactured solutions display our theoretical findings, and a spinodal decomposition example portrays the robustness of our approach.

Time and place: , Abels Utsikt (NHA 1259)
Time and place: , Erling Svedrups plass and Zoom https://uio.zoom.us/j/64912028556?pwd=QmJpa1ZPS0hBNTFZUDhzWDlaMmJKQT09

Traditional quantile estimators are not well-suited for data streams because the memory and computational time increase with the volume of data received from the stream. Incremental quantile estimators refer to a class of methods designed to maintain quantile estimates for data streams. These methods operate by making small updates to the estimate every time a new observation is received from the stream. In this presentation, I will introduce some of the incremental quantile estimators we have developed.

Time and place: , Niels Henrik Abels hus, 9th floor

Your brain has its own waterscape: whether you are reading, thinking or sleeping, fluid flows through or around the brain tissue, clearing waste in the process. These biophysical processes are crucial for the well-being and function of the brain. In spite of their importance we understand them but little, and mathematical and computational modelling could play a crucial role in gaining new insight. In this talk, I will give an overview of mathematical, mechanical and numerical approaches to understand mechanisms underlying pulsatility, fluid flow and solute transport in the human brain. Topics include fluid-structure interactions, generalized poroelasticity, mixed finite element discretizations and preconditioning, uncertainty quantification, and optimal control.

Time and place: , NHA, Abels Utsikt

As we bid farewell to 2023 and welcome the first hints of winter, we invite you to take part in "The Winds of STORM" workshop!

Time:

Workshop at University of Oslo

Time and place: , NHA108

C*-algebra seminar by Jordy Timo van Velthoven (University of Vienna)

Time and place: , Erling Svedrups plass and Zoom https://uio.zoom.us/j/66849037258?pwd=NkNiR0lkbm5VK0VyMytVZW4vV0hNQT09
Time:

This is a half-day online workshop on the numerics and theory of conservation laws and fluid equations. Abstracts and Zoom link can be found here.

Time and place: , Room 1020, Niels Henrik Abels hus

The Section 4 seminar for the Autumn of 2023 will be held on Mondays at 10:15–12:00 (see the schedule)

Time and place: , The Norwegian Academy of Science and Letters

30-31 October 2023, Oslo, Norway. 

 

The symposium is a follow-up of six highly successful previous DNVA-RSE Norway-Scotland Symposia. Topics of this year's symposium include: Water Waves and Internal Waves, and the widened scope to include the following multi- and inter-disciplinary marine topics: Hydrodynamic processes in the coastal ocean and fjords, Microbial processes, Robotics for observations in the ocean, Corals and plankton, and Arctic-related problems. 

 

 

Time and place: , NHA 723 and Online
Time and place: , Abels Utsikt (NHA 1259)
Time and place: , Room 1120, Niels Henrik Abels hus

The Deep learning seminar will be held on Thursdays at 10:15–12:00. Please register to this mailing list if you would like updates.

Time and place: , Hammamet, Tunisia

The conference is an occasion to bring together researchers in the beautiful Hammamet to discuss on the recent developments in stochastics with applications to mathematical physics and finance.

An event dedicated to the memory of Habib Ouerdiane.

Time and place: , Niels Henrik Abels hus, 9th floor

Fluid efflux from the brain plays an important role in solute waste clearance. Current experimental approaches provide little spatial information or data collection is limited due to short duration or low frequency of sampling. One approach shows tracer efflux to be independent of molecular size, indicating bulk flow, yet also decelerating like simple membrane diffusion. In an apparent contradiction to this report, other studies point to tracer efflux acceleration following infusions. In this talk, I will share a stylized advection-diffusion model for clearance of waste, which reconciles the apparent contradiction, and discuss methods to validate it with novel MRI data. Being stylized, it is also simple enough to permit a dimensional analysis which indicates that clearance of waste from the brain is governed by three dimensionless quantities including a potential bottle-neck for clearance due to transport across the surface membranes.