All Years Seminars
[INMA] 2021-10-19 (14h) : Multi-Stage Stochastic Programming for AC Optimal Power Flow Problems
At Euler building (room a.002)
Speaker :
David Wozabal (Technical University of Munich)
Abstract : We propose the first computationally tractable framework to solve multi-stage stochastic optimal power flow (OPF) problems in alternating current (AC) power systems. To this end, we use recent results on convex semi-definite programming (SDP) relaxations of OPF problems in order to adapt the SDDP algorithm for problems with a Markovian structure employing scenario lattices to discretize the underlying randomness. We show that the usual SDDP lower bound remains valid and that the algorithm converges to a globally optimal solution of the stochastic AC-OPF problem as long as the SDP relaxations are tight. In the last part of the paper, we set up an extensive case study demonstrating the practical viability of our approach. In particular, we use the IEEE RTS-GMLC network to set up a storage sitting, sizing, and operation problem under uncertainty about demand and renewable generation. We show that the convex SDP relaxation of the stochastic problem is tight except in very rare cases. Furthermore, we demonstrate that after a reasonable number of iterations the algorithm finds a policy with a relatively small SDDP optimality gap that yields a significant added value over rolling deterministic planning.
[INMA] 2021-10-12 (14h) : Optimization in Steel Industry
At Euler building (room a.002)
Speaker :
Vivian De Smedt (PSI Metals Belgium)
Abstract : What are some of the optimization problems of the steel industry? We will discuss the differences between two approaches of the optimization problems: black box vs. expert systems. The size of the solution space being very large some heuristic approaches are needed. We will discuss how to select the heuristics and what are the strong and weak points of the different approaches. The optimization project have to be integrated into workflow that less automatic and have its strong points. We will discuss how to take into account this aspect of the problematic in the conception of the solution
[INMA] 2021-10-05 (14h) : Neuromorphic control principles
At Euler building (room a.002)
Speaker :
Guillaume Drion (Université de Liège)
Abstract : Owing to the recent advances in control engineering and machine learning, and combined with the remarkable improvement of sensors, actuators and computer power, modern high-performance computing systems far surpass human performance in a plethora of complex tasks. However, they consume megawatts of power, are optimized for specific tasks, and are hardly portable. In sharp contrast, biological brains are energy-efficient, are polyvalent, and show impressive adaptive capabilities in uncertain environments. These main differences between brains and current computing architectures are a crucial bottleneck for the expansion of automation in modern society. This situation has led many universities and world-leading companies, which include IBM, Intel, IMEC, or Thales, to investigate novel, brain-inspired computing systems and artificial intelligence technologies, an approach called neuromorphic computing. In this talk, we will approach the design of neuromorphic computing systems from a control engineering approach. We will first study how excitability, a key property of neuronal signaling, can be analyzed and designed following a nonlinear, multiscale feedback approach. Secondly, we will see how such neuromorphic systems can be controlled through loop shaping via a physiological mechanism called neuromodulation. Finally, we will exploit these brain-inspired mechanisms to improve artificial neural network adaptivity and long-term memory on the one hand, and design robust and controllable neuromorphic electronic systems on the other hand
[INMA] 2021-09-28 (14h) : Convex Optimization of Bioprocesses
At Euler building (room a.002)
Speaker :
Josh Taylor (University of Toronto)
Abstract : In this talk, we begin by optimizing the gradostat, in which several chemostats are interconnected by mass flow and diffusion. The gradostat is of interest both as a classical nonlinear system and because the basic network structure and nonlinearities appear in a wide variety of bioprocesses, including wastewater treatment. We formulate a convex relaxation of the gradostat. The relaxation is exact under several conditions, for instance, if the gradostat is outflow connected and its flow matrix is irreducible. When the microbial growth in the bioreactors is described by the Monod or Contois functions, the relaxation is a second-order cone program, which can be solved at scales of over 10^5 variables in minutes with industrial software. We also discuss how to extend the work to a general class of bioprocesses, and present an example based on wastewater treatment.
[INMA] 2021-09-21 (14h) : From theoretical to computable convergence rate of push-sum for consensus
At Euler building (room a.002)
Speaker :
Gerencser, Balazs
Abstract : We know that reaching average consensus using only local communication along a network is a fundamental building block in the area of distributed computing, leading to applications such as sensor fusion and distributed optimization.
We currently analyze schemes based on one such protocol, push-sum, and our target is to understand their convergence speed. We prove a bound on the almost sure convergence rate that is also computable for a class of push-sum algorithms. This extends the works of Iutzeler, Ciblat and Hachem (2013) on similar bounds but in a more restrictive setup and conclusion, and complements the results of Gerencsér and Gerencsér (2019) identifying the exact convergence rate but providing no computable access or approximation
Seminars
Subscribe (ICS)
INMA Contact Info
Mathematical Engineering (INMA)
L4.05.01
Avenue Georges Lemaître, 4
+32 10 47 80 36
secretaire-inma@uclouvain.be
Mon – Fri 9:00A.M. – 5:00P.M.
JOIN US