AI for Time Series

elke twee weken, Leuven & online
seminariereeks
VAIA, Flanders AI Research & KU Leuven STADIUS

Gemeten data of observaties komen erg vaak voor in de vorm van tijdreeksen: scalaire of vectorsequenties van datapunten geïndexeerd in de tijd. Tijdreeksen duiken in allerlei maatschappelijke en wetenschappelijke domeinen op en door de enorme hoeveelheden beschikbare data en toegenomen computerkracht wint de analyse van tijdreeksen ook steeds meer aan belang.

De toepassingen van tijdreeksanalyse kunnen grotendeels ingedeeld worden in simulatie, voorspelling, clustering en anomaliedetectie. Een ander toepassingsgebied is modelgebaseerde regeltechniek, waar dynamische modellen geschat worden aan de hand van tijdreeksen. Verscheidene onderzoeksgroepen in het Vlaams AI-onderzoeksprogramma verrichten onderzoek van wereldklasse in verband met tijdreeksen, zowel voor de ontwikkeling van algoritmes en tools, als voor een brede reeks toepassingen.

In een recente rondvraag bij de Vlaamse AI-gemeenschap, bleek dat het onderwerp ‘tijdreeksen’ het meest gevraagd werd om toekomstige workshops en cursussen over te organiseren. Met deze seminariereeks komen we aan die vraag tegemoet en brengen we onderzoekers die geïnteresseerd zijn in, of onderzoek verrichten naar, tijdreeksen samen. We bieden hen en andere belangstellenden een gevarieerd programma met nationale en internationale sprekers.

AI for Time Series Seminars

This talk explores opportunities in combining insights from systems theory with tools from machine learning, for data driven modelling of dynamic systems.

John Lataire discusses the data-driven modelling of Linear Time-Invariant (LTI) systems with Gaussian Processes (GP) regression. First, GP regression in general, and Time domain and frequency domain expressions of LTI systems are reviewed. Then, relevant system-specific properties, s.a. causality and stability are encoded in kernels, used as prior knowledge for estimation purposes.

Care is given to visual interpretations of this prior knowledge in the spectral domain. Finally, recent results are shared on the estimation of the more challenging situation, where the systems are lightly damped. The combination of the non-parametric local rational model (LRM) estimator with the GP regression approach is proposed.

After an introduction to the field, we will discuss how the marriage of power systems engineering and artificial intelligence can aid to improve the visibility on the low voltage distribution grid. This enables optimized use of the presently installed assets and helps to limit future investments, so the distribution grid becomes an enabler of the energy transition, rather than a costly bottleneck.

Currently, sports is an incredibly data rich domain as it is possible to collect massive amounts of data from both training sessions and matches. Typically, this data comes in the form of time series such as sensor data (e.g., accelerations, heart rate, GPS, etc.), event stream data, and optical tracking data. The availability of this data has driven an explosion of interest in the automated analysis of sports. The goal of this talk is to provide an overview of this area with illustrative examples arising out of work done in my research group.

I will present work being conducted in the Computational Creativity Lab at the VUB which explores the use of statistical models to build cognitive representations of sequence data. Sequence modelling is a central part of cognitive systems. The notion of sequence can be thought of as an abstraction of time series used to account for cognitive flexibility in the perception of time. The goal of our work is to bridge the gap between unsupervised learning and knowledge-based reasoning in cognitive systems.

A deep neural network model typically is learned solely from data in the form of input-output pairs ignoring domain knowledge that additionally might be available. When domain knowledge is injected to serve as a learning guidance it is expected that the need for annotated data is relaxed and training is less dependent on the initialization of the model parameters. Domain knowledge can be provided in many different types and forms. In this seminar, domain knowledge is assumed to be given as inequality constraints which appear naturally in practice. Compared to other neuro-symbolic approaches the discussed method is also able to incorporate non-linear inequality constraints and does not require to first transform the constraints into some ad-hoc term that can be added to the learning (optimisation) objective.

The definition of adequate metrics between objects to be compared is at the core of many machine learning methods (e.g., nearest neighbors, kernel machines, etc.). When complex objects are involved, such metrics have to be carefully designed in order to leverage on desired notions of similarity.
This talk covers my works related to the definition of new metrics for structured data such as time series or graphs.

Praktisch

  • +/- elke twee weken,
    vanaf 28 oktober 2021
    14.30-15.30u
  • Locatie: Campus Arenberg, Leuven
    + online streaming
  • Taal: Engels
  • Contact: Philippe Dreesen & Katrien De Cock
  • Doelgroep: alle geïnteresseerden in onderzoek naar tijdreeksen en AI

Inschrijven

  • Prijs: gratis
  • Inschrijven is niet nodig, je kan gewoon naar de (online) lezing komen.
    Als je graag een reminder ontvangt, geef dan je contactgegevens hieronder op, dan ontvang je een melding op de dag van het seminarie.

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