Tisdag 2 april 2024, kl 15:15, Magnus Herberthson, Matematiska institutionen, Linköpings universitet
Titel: The central limit theorem for random walks on bounded domains
Sammanfattning: The standard central limit theorem typically assumes independent identically distributed (i.i.d.) random variabels X_i (with E[X_i]=0 and finite variance V[X_i]). A scaled average of N terms will then converge to a normal distribution as N -> oo, and the variance of this normal distribution is directly related to V[X_i].
We consider a random walk in a bounded domain Omega (for simplicity in the in the plane) which will imply that the the random walk variables X_i are not any longer
independent. A central limit theorem still ensures a limiting distribution for the rescaled averages as the number of terms increases, but now the covariance matrix of the limiting distribution is not so obvious. We will discuss how this covariance matrix is given by the geometry of the bounding domain Omega.
Måndag 5 februari 2024, Björn Morén,Matematiska institutionen, Linköpings universitet
Titel: Experiences From Being a Postdoc at a Medical Physics Unit
Sammanfattning: This presentation will be about my postdoc period for half a year at McGill University, Montreal, Canada. I was at a Medical Physics Unit with much research focus on AI and brachytherapy, which is a type of radiation therapy where the radiation is given from within the body. In the first part of the presentation, I will describe how the cooperation was formed, my motivation for going there, and how it is to be in an environment that is very different from what you are used to.
In the last part I will discuss one of my projects during the visit in more details. One of their specialties is developing new types of delivery techniques for brachytherapy as different techniques are used for each treatment site. When I came there, they worked on a new prototype for brachytherapy treatment of rectal cancer, and they were planning the next steps to do a clinical trial. Our research project was aimed at investigating positional uncertainties in the treatment and the robustness of their delivery prototype.
Måndag 24 april kl 13.15 David Abramian, Institutionen för medicinsk teknik, Linköpings universitet
Titel: Introduction to convolutional neural networks with applications in medical imaging
Sammanfattning: Convolutional neural networks (CNNs) have driven the recent explosion in interest in artificial neural networks, advancing the state-of-the-art for a variety of computer vision tasks, as well as bringing a number of consumer applications to the public. Although somewhat displaced in recent years by the development of more advanced models, they are still the de facto standard for image applications in deep learning. This seminar will provide a gentle introduction to CNNs, discussing their principles
Plats: Kompakta rummet, B-huset, ingång 23, plan 2, Campus Valla
Onsdag 1 juni, Ezio Venturino, Università di Torino
Titel: Fighting alien species invasions through mathematical modeling
Sammanfattning: Recently, we have investigated the phenomenon of native populations replacement by exotic ones, focusing on accidentally or intentionally introduced species in Italy and UK. Two major cases are of interest. American grey squirrels are gradually outcompeting the indigenous red ones both in Italy and in UK. In the latter case, the situation is worsened by the presence of a virus, carried by the aliens, for which it is harmless, but which ultimately is found lethal for the native species. In Italy the European hare is slowly forcing the extinction of the native mountain hare. The main difference in this case is that the contacts among the two occur just on the boundary region of the territories occupied by the two species. This allows us to formulate a non-classical interaction model, based on the concept of herd behavior. The latter is extended to other possible situations, showing the onset of some new features in the phase space, revealing quite different results from the classical ones.
OBS! Lokal: C3
Anordnas i samarbete med Matematiska kollokviet
Onsdag 11 maj 2022, Magnus Herberthson, Matematiska institutionen, Linköpings universitet
Titel: Characterising the second order moments of diffusion tensor distributions
Sammanfattning: In magnetic resonance imaging (MRI), it is possible to probe tissue on a sub-resolution level. The signal obtain by MRI is then formed by a family of diffusion tensors, with may have certain statistical properties. In this talk we are interested in characterising the second order moment of this family, which is a forth order tensor with certain symmetries.
Plats: i Hopningspunkten som ligger i B-huset, ingång 23, plan 2, Campus Valla i Linköping.
Seminariet är ett samarrangemang med Matematiska kollokviet.
Onsdag 21 oktober 2020, Åsa Holm, Furlands Revisionsbyrå
Forskarskolan fortsätter att uppmärksamma sitt 20-årsjubileum med ännu ett distansseminarium av en forskarskolealumn.
Åsa Holm över ämnet: Tillämpad optimering möter den riktiga verkligheten - tema strålbehandling (och lite ekonomi).
Onsdag 14 oktober 2020, Andreas Rietz, Scania
Onsdagen 14 oktober ger Andreas Rietz (med bakgrund i forskarskolan i tvärvetenskaplig matematik) ett distansseminarium med start 13.15.
Ämnet som avhandlas är: Solid mechanics of trucks, and a remark on the functional spaces (Lastbilars hållfasthet, och lite om funktionsrummen.)
Onsdag 22 januari 2020, Elina Rönnberg, Matematiska institutionen, Linköpings universitet
Titel: Efficient use of hardware resources in avionic systems
Sammanfattning: A key ingredient when designing an avionic system – i. e. the electronic system of an aircraft – is to make sure that it always can be trusted. In modern integrated modular avionic systems, different aircraft functions share hardware resources on a common avionic platform. For such architectures, it is necessary to create a spatial and temporal partitioning of the system to prevent faults from propagating between different functions. One way to establish a temporal partitioning is through pre-runtime scheduling.
While the avionic systems are growing more and more complex, so is the challenge of scheduling them. Scheduling of the system has an important role when a new avionic system is developed. Typically, functions are added to the system over a period of several years and a scheduling tool is used both to determine if the platform can host the new functionality and, in case this is possible, to create a new schedule.
In this talk, I will discuss a design case from Saab Aeronautics and present an optimisation-based scheduling tool that we have developed. From an optimisation point of view, the problem can be described as a rich multiprocessor scheduling problem that also includes a communication network to be scheduled. Results are presented for practically relevant large-scale instances with up to 60 000 tasks.
Torsdag 17 maj 2018, Daniel Petersson, Veoneer
Seminariet är ett samarrangemang med Seminarier i Optimeringslära.
Titel: Eyes for self-driving cars
Sammanfattning: The development of technical systems has in many ways been dramatically changed during the last years through the breakthrough of deep learning. Traditional machine learning techniques using hand-crafted features have been successful for many applications, such as object detection in vision systems. However, the deep learning framework often enables higher performance, shared computations between different applications, and the ability to solve more advanced problems such as autonomous driving.
In the seminar, I will share experiences from the Veoneer development of vision systems for cars, such as data driven development and how the new advancements in the field of deep learning affect our products/services, as well as our ways of working.
Onsdag 15 november 2017, Jan-Åke Larsson, Institutionen för systemteknik, Linköpings universitet
Seminariet är ett samarrangemang med Matematiska kollokviet.
Titel: Efficient simulation of some quantum computer algorithms
Sammanfattning: A long-standing aim of quantum information research is to understand what gives quantum computers their advantage. Such an understanding would be of great benefit when attempting to build a quantum computer. Here we present a framework that uses classical resources but still is able to efficiently run, for example Deutsch-Jozsa and Simon's algorithms, and also can run Shor's factoring algorithm with some systematic errors. We also perform an experiment factoring 15 using classical pass-transistor logic at room temperature, with smaller systematic errors than any former experimental implementation, and the same amount of resources in time and space as a scalable quantum computer. Our results give further insight into the resources needed for quantum computation, aiming for a true understanding of the subject.
Onsdag 3 maj 2017, David Rule, Matematiska institutionen, Linköpings universitet
Seminariet är ett samarrangemang med Matematiska kollokviet.
Titel: The global boundedness of Fourier integral operators on local Hardy spaces
Sammanfattning: The question of the local $L^p$-boundedness of Fourier integral operators when $p\neq2$ was answered in work of Seeger-Sogge-Stein in the early nineties. But only recently have Ruzhansky-Sugimoto found sufficient conditions to prove global $L^p$-boundedness. We build on their methods to prove the global boundedness of Fourier integral operators in the (mostly quasi-Banach) setting of local Hardy spaces $h^p$ in the range $n/(n+1) < p \leq 1$. This is joint work with Salvador Rodríguez-López and Wolfgang Staubach.
Onsdag 1 februari 2017, Clas Rydergren, Institutionen för teknik och naturvetenskap, Linköpings universitet
Seminariet är ett samarrangemang med Matematiska kollokviet.
Titel: New sources of input data for travel demand estimation models
Sammanfattning: Forecasts of how journeys are made, from where and to where, is usually done using simple mathematical models. The results from the models are used as estimates of the load on the transport system. Estimates are made for the load today, in the future, and to estimate the change in travel demand when changes in the infrastructure are made. The model result is critical input to traffic planners.
Different types of models are used depending on, among other things, if the analysis requires the results to include all modes of transport, or not, and the length of the forecast horizon. Models for long-term forecasts (several years) often contain components to describe the travelers' values and perceptions whereas models for the current situation or with a very short forecast horizon, often is based exclusively a network model and data from dedicated traffic measurements.
During this seminar, I will present an example of a traditional demand model, and exemplify how this model is used. The ongoing digitization have led to new sources of input data for this type of models. I will exemplify this by presenting inputs used in a couple of research projects ongoing at the Division of Communications and Transport System (KTS) at ITN.
