Centre for Mathematics, University of Coimbra

Seminars - Historic

Numerical Analysis and Optimization

Constrained partitions in graphs: bio and financial applications

2017-02-15

Speaker: Pedro Martins (IPCoimbra and CMAF-CIO)

This seminar addresses partition problems in graphs, from an applied perspective. We discuss results and formulations, ranging from very restrictive partition components (partition into cliques) to less restrictive ones (partition into trees - a forest). We also compare these results with...

Mathematics in Industry: Some successful collaborations

2014-09-10

Speaker: Manuel B. Cruz (LEMA/ISEP)

The interaction Mathematics-Industry has suffered a great development in the latest years. The genesis of EU-MATHS-IN, the European Network for Mathematics in Industry, as well as the spread of several national networks across Europe, illustrates the evolution and potential of that area of...

An overview of some Spanish infrastructure focused on promoting the transfer of mathematics to industry

2014-09-10

Speaker:

Peregrina Quintela (Univ. Santiago de Compostela)

In the talk two infrastructures aimed at boosting transfer to industry will be presented: The Spanish Network for Mathematical and Industry (math-in) and the Technological Institute of Industrial Mathematics (ITMATI). Some details of how they were formed, the type of legal entity chosen, the...

Non-Fickian models for biodegradable drug eluting stents

2014-07-09

Speaker: Jahed Naghipoor (CMUC)

In recent years, mathematical modeling of cardiovascular drug delivery systems has become an effective tool to gain deeper insights in the cardiovascular diseases like atherosclerosis. In the case of coronary biodegradable stent which is a tiny expandable metallic mesh tube covered by...

Explicit Leap-frog DG method for time domain electromagnetic wave propagation

2014-06-04

Speaker: Maryam Khaksar Ghalati (CMUC, Univ. Coimbra)

The discontinuous Galerkin time domain methods are now popular and efficient way for the solution of wave propagation problems. The motivation of modeling scattered electromagnetic wave propagation through the human eye’s structure brings us to solving aMaxwell’s equations with...

Nonlinear propagation of waves of short wavelength in dispersive systems

2014-05-28

Speaker: Sílvio Gama (Univ. Porto)

We discuss the nonlinear propagation of waves of short wavelength in dispersive systems and we present the simplest nonlinear short-wave dynamics: $u_{tx} = u - 3 u^2$. We present an algorithm to integrate numerically this equation for periodic and non-periodic boundary conditions. We also...

Nonlocal models for image processing: properties and applications

2014-05-23

Speaker: Eduardo Cuesta (Univ. Valladolid, Spain)

One of the alternatives for the mathematical formulation of image processing problems is based on local, nonlinear PDEs models. In the first part of the talk, a brief overview of them, with special regards to morphological and structural properties, will be done. In the second part, some...

On the numerical approximation of algebraic equations with symmetries

2014-05-21

Speaker: Angel Durán (Univ. Valladolid, Spain)

The resolution of systems of algebraic equations with symmetry groups appears in the mathematical treatment of many models, [1, 2]. These groups consist of transformations that map solutions of the algebraic system into other solutions. Some consequences of the existence of such symmetry...

GLODS: Global and Local Optimization using Direct Search

2014-02-05

Speaker:

Ana Luísa Custodio (Univ. Nova de Lisboa, Portugal)

Locating and identifying points as global minimizers is, in general, a hard and time-consuming task. Difficulties increase when the derivatives of the functions defining the problem are not available for use. In this talk, we propose a new class of methods suited for global derivative-free...

Numerical solution of Sturm--Liouville problems via Fer streamers

2014-01-08

Speaker: Alberto Gil C. P. Ramos (Univ. Cambridge, UK)

We address the numerical challenge of solving Sturm-Liouville problems in Liouville's normal form, with regular boundary conditions and a continuous and piecewise analytic potential. The novelty of our approach, which is based on a non-standard truncation of Fer expansions, which we call...

Mathematical modelling of Angiogenesis -flow, elasticity and experiments

2013-11-20

Speaker: Rui Travasso (Center for Computational Physics, Univ. Coimbra)

Understanding angiogenesis in a pathological setting is a challenging problem with important consequences for diagnosis and treatment of severe diseases such as cancer. We present a multi-scale phase-field model that combines the benefits of continuum physics description and the capability...

Some recent developments of a non-dissipative DGTD method for time-domain electromagnetics

2013-10-29

Speaker: Stéfane Lanteri (INRIA Sophia Antipolis-Méditerranée)

Nowadays, a variety of modeling strategies exist for the computer simulation of electromagnetic wave propagation in the time domain. Despite a lot of advances on numerical methods able to deal accurately and in a flexible way with complex geometries through the use of...

Smoothing and worst-case complexity for direct-search methods in nonsmooth optimization

2012-10-10

Speaker: Nima Garmanjani (Univ. Coimbra)

For smooth objective functions it has been shown that the worst-case cost of direct-search methods is of the same order as the one of steepest descent. Motivated by the lack of such a result in the nonsmooth case, we propose, analyze, and test a class of smoothing...

A derivative-free optimization algorithm with subspace technique

2012-10-03

Speaker: Zaikun Zhang (Univ. Coimbra)

We will talk about optimization algorithms that do not use derivatives, namely, derivative-free algorithms. We discuss how to incorporate subspace techniques into this type of algorithms, and present a new derivative-free algorithm with subspace techniques. For the new algorithm,...

FEM solutions of some Boussinesq-type models for surface water waves

2012-07-11

Speaker: Nuno Lopes (CMAF, Univ. Lisboa)

A class of improved Boussinesq-type models to simulate the propagation and generation of nonlinear dispersive waves is presented. The models are derived in order to keep some dispersive characteristics of higher-order ones. Some stability properties of the numerical models are discussed....

On the separability of clusters

2012-06-20

Speaker: Jorge Orestes Cerdeira (ISA/UTL)

Separability of clusters is an issue that arises in many different areas, and is often used in a rather vague and subjective manner. We introduce a combinatorial notion of interiority to derive a global view on separability of a set of entities. We develop this approach further to...

Towards a virtual retina - a multidisciplinary approach

2012-06-20

Speaker: Miguel Morgado (IBILI/DFUC)

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Sampling in 2D: specificities, difficulties and applications

2012-06-20

Speaker: José Manuel Rebordão (DF/FCUL)

Sampling strategies are a fundamental part of any measurement process. In the signal framework (one-dimensional, 1D - usually the time), sampling is a well-controlled process. For two (images, 2D) and three (volumes, 3D) spatial dimensions, one is frequently faced with unknown objects or...

Strong discontinuities in the scope of the discrete crack approach

2012-05-23

Speaker: Daniel Dias da Costa (Univ. Coimbra)

The use of the discrete crack approach and Nonlinear Fracture Mechanics opened the possibility of accurately modelling fracture behaviour of quasi-brittle materials, such as concrete, mortar and masonry. In this approach, it is assumed that microcracking localises into a surface of...

An agency for Mathematics in interaction with enterprises and society in France

2012-04-26

Speaker: Christophe Prud'homme (Univ. Grenoble, France)

I will discuss the creation and the first year of existence of the french Agency for Mathematics in Interaction with Enterprises and Society (AMIES) [1]. First I start with the context in which the agency was funded then I present the organisation, its objectives and the tools it provides to...

Anomalous diffusion imaging through fractional order calculus

2011-12-14

Speaker: Ercília Sousa (CMUC/Mat. FCTUC)

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Applications of retinal imaging with photoreceptor resolution

2011-12-14

Speaker: Sérgio Nascimento (Univ. Minho, Braga)

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Support vector machines in medical image analysis

2011-05-13

Speaker: Rui Bernardes, Pedro Serranho, João Duarte (IBILI, Coimbra)

Support Vector Machines (SVM) are a classification tool with broad applications. The process is based on the representation of each element of the set in a multidimensional feature space.This machine learning method relies then on optimization to find a set of splitting hyperplanes that...