Roberto Font

Biometric Vox · R&D Department

The COVID-19 pandemic has led to the saturation of public health services worldwide. In this scenario, the early diagnosis of SARS-Cov-2 infections can help to stop or slow the spread of the virus and to manage the demand upon health services. This is especially important when resources are also being stretched by heightened demand linked to other...

Performance metrics, such as Equal Error Rate or Detection Cost Function, have been widely used to evaluate and compare biometric systems. However, they seem insufficient when dealing with real-world applications. First, these systems tend to include an increasing number of subsystems, e.g. aimed at spoofing detection or information management. As...

Service robots are expected to operate in real-world environments, which are inherently open-ended and show a huge number of potential situations and contingencies. This variability can be addressed applying reinforcement learning, which enables a robot to autonomously discover an optimal behavior through trial-and-error interactions with the envir...

Automatic Speaker Verification (ASV) is being implemented in many applications, where maximum security and robustness against attacks must be guaranteed. One of the most challenging attacks that an ASV system can face is the so called “logical access attack”, in which the attacker has the possibility to directly inject a compromised audio sample in...

Non-functional properties are an essential part of any software solution. There is a lot of literature on what non-functional properties are but, unfortunately, there is also a lot of disagreement and different points of view on how to deal with them. Non-functional properties, such as safety or dependability, become particularly relevant in the co...

We test a recently proposed approach to optimal feedback control of nonlinear systems leading to an iterative descending strategy [24]. We start by discussing the numerical implementation of this strategy, and propose a number of improvements that can speed up the computation process by up to two orders of magnitude. The resulting algorithm is then...

These notes are concerned with the numerical resolution of Partial Differential Equations (PDE) by the Finite Element Method (FEM). Emphasis is placed in the practical numerical resolution of this type of problems by using the free software FreeFem++. Theoretical background is briefly reviewed (without entering in technical details) and a number of...

On the basis of the classical variational reformulation of optimal control problems, we introduce a numerical scheme for solving those problems where the goal is the computation of optimal controls in feedback and digital forms defined on a discrete time mesh. The algorithm reduces the computation of such controls to solving a suitable nonlinear ma...

Under certain circumstances, like intelligence gathering missions, emergency rising or special operations, manned submarines may need to perform maneuvers with very specific requirements. In these cases, submarines perform small or large ballast tanks blowing and venting operations to modify the buoyancy of the vehicle or/and to correct trimming an...

The blowing and venting of ballast tanks could potentially be used as a complementary control system to improve the manoeuvrability of manned sub-marines. To test the feasibility of such a control system, we first propose a mathematical model for these operations. Then, the model is applied to the control of an emergency manoeuvre by using only the...

Motivated by the study of the potential use of blowing and venting operations of ballast tanks in manned submarines as a complementary or alternative control system for manoeuvring, we first propose a mathematical model for these operations. Then we consider the coupling of blowing and venting with the Feldman, variable mass, coefficient based hydr...

Motivated by the study of the potential use of ballast tanks blowing and venting operations as a way to improve the manoeuvrability of manned submarines, the aim of this work is to develop a computer tool capable of simulating any manoeuvre involving blowing and venting. We first propose a mathematical model for these operations which is coupled wi...

The aim of this work is to obtain mathematical models for both the blowing and venting of ballast tanks, as well as the effect of these operations over the submarine behavior. Although tanks are usually blown only on emergency situations, blowing and venting can potentially be used as a suitable control mechanism for specific manoeuvres, not only i...

The problem of computing numerically the boundary exact control for the system of linear elasticity in two dimensions is addressed. A numerical method which has been recently proposed in [P. Pedregal, F. Periago, J. Villena, A numerical method of local energy decay for the boundary controllability of time-reversible distributed parameter systems. S...