
Figueiredo, Pedro N.; Figueiredo, Isabel N.; Prasath, Surya; Tsai, Richard
Background. The aim of this work is to present an automatic colorectal polyp detection scheme for capsule endoscopy. Methods.
PillCam COLON2 capsulebased images and videos were used in our study. The database consists of full exam videos from
five patients. The algorithm is based on the assumption that the polyps show up as a protrusion in the captured images and is
expressed bymeans of a Pvalue, defined by geometrical features. Results. Seventeen PillCamCOLON2 capsule videos are included,
containing frames with polyps, flat lesions, diverticula, bubbles, and trash liquids. Polyps larger than 1 cmexpress a Pvalue higher
than 2000, and 80% of the polyps show a...

Korobeinikov, Andrei; Kovacec, Alexander; McGuinness, Mark; Pascoal, Marta; Pereira, Ana; Vilela, Sónia
In modern reversible hydroelectric power stations it is possible to
reverse the turbine and pump water up from a downstream reservoir
to an upstream one. This allows the use of the same volume of water
repeatedly and was speciﬁcally developed for hydroelectric stations
operating with insuﬃcient water supply. Pumping water upstream
is usually done at times of low demand for electricity, to build up
reserves in order to be able to produce energy during peak hours, thus
balancing the load and making a proﬁt on the price diﬀerence.
In this paper, we consider a branched model for hydroelectric
power stations interacting in a complex cascade arrangement. The
goal of this...

Antunes, S. D.; Antunes, P. M. V. C. D.; Vicente, M. A. F.
In the last years, we assisted to the development of new high precision machine tools: the
hexapod machines. We tried to use the hexapod machine as an artefact for CMM’s calibration.
However, given their cost and their resolution, they are not the best solution for a
transportable artefact. By modifying the hexapod structure, we develop two different
artefacts: one for local CMM’s calibration and another one for global calibration.
Local calibration allows us the determination of the transfer function characterizing the sensor
displacement of the CMM. This local calibration is based on the measurement of a rigid
artefact of a known geometry, derived from hexapod geometry, which...

Figueiredo, Isabel N.; Leal, Carlos F.
We analyse the sensitivity of the solution of a nonlinear obstacle plate problem, with respect to small perturbations of the middle plane of the plate. This analysis, which generalizes the results of Rao and Sokolowski 1987, Rockafeller 1989 for the linear case, is done by application of an abstract variational result Levy 1999, where the sensitivity of parameterized variational inequalities in Banach spaces, without uniqueness of solution, is quantified in terms of a generalized derivative, that is the protoderivative. We prove that the hypotheses required by this abstract sensitivity result are verified for the nonlinear obstacle plate problem. Namely, the...

Heinkenschloss, Matthias; Vicente, Luís N.
In this paper we extend the design of a class of composite–step trust–region SQP methods and their global
convergence analysis to allow inexact problem information. The inexact problem information can result from iterative linear
systems solves within the trust–region SQP method or from approximations of first–order derivatives. Accuracy requirements
in our trust–region SQP methods are adjusted based on feasibility and optimality of the iterates. Our accuracy requirements
are stated in general terms, but we show how they can be enforced using information that is already available in matrix–free
implementations of SQP methods. In the absence of inexactness our global convergence theory is equal to that...

Patrício, M. F.
In this paper we study numerical solutions for a hyperbolic system of equations using finite differences. In this setting, we propose the method of lines, with high precision in space. A class of some explicit, implicit and also semiimplicit schemes, with code variable methods, are presented. Finally, the analysis of some qualitative and quantitative proprieties of these methods is included.

Ferreira, J. A.; Mouro, A. P.; Oliveira, P.
In certain cases, quasilinear convectiondiffusionreaction equations range from parabolic to almost hyperbolic, depending on the ratio between convection and diffusion coefficients. From a numerical point of view, two main difficulties can arise related to the existence of layers and/or the nonsmoothness of the coefficients of such equations. In this paper we study the steadystate solution of a convectiondominated problem. We present a new numerical method based on the idea of solving an associated modified problem, whose solution corresponds to a lifting of the solution of the initial problem. The method introduced here avoids an a priori knowledge of the layer(s)...

Fernandes, Rosário; Fonseca, C. M. da
In 1979, Ferguson characterized the periodic Jacobi matrices with given eigenvalues and showed how to use the Lanzcos Algorithm to construct each such matrix. This article provides general characterizations and constructions for the complex analogue of periodic Jacobi matrices. As a consequence of the main procedure, we prove that the multiplicity of an eigenvalue of a periodic Jacobi matrix is at most 2.

Teixeira, José Carlos
http://doi.acm.org/10.1145/232301.232319

Pereira, J. M. S. Simões
http://doi.acm.org/10.1145/363235.363243

Heinkenschloss, Matthias; Vicente, Luís N.
An interface between the application problem and the nonlinear optimization algorithm is proposed for the numerical solution of distributed optimal control problems. By using this interface, numerical optimization algorithms can be designed to take advantage of inherent problem features like the splitting of the variables into states and controls and the scaling inherited from the functional scalar products. Further, the interface allows the optimization algorithm to make efficient use of userprovided function evaluations and derivative calculations.

Facchinei, Francisco; Júdice, Joaquim; Soares, João
We present a method for generating boxconstrained nonlinear programming test problems. The technique allows the user to control some properties of the generated test problems that are know to influence the behavior of algorithms for their solution. A corresponding set of Fortran 77 routines is described in a companion algorithm (774).

Facchinei, Francisco; Júdice, Joaquim; Soares, João
We describe a set of Fortran routines for generatig boxconstrained nonlinear programming test problems. The technique, as described by Facchinei et al. (this issue), allows the user to control relevant properties of the generated problems.

Calamai, Paul H.; Vicente, Luís N.
This paper describes software for generating test problems for quadratic bilevel programming. The algorithm constructs problems with a number of favorable properties that can be selected and controlled by the user. The intention is to provide a set of FORTRAN 77 routines that can be used for testing, verifying, and comparing solution techniques for these problems.

Calamai, Paul H.; Vicente, Luís N.
This paper describes a technique for generating sparse or dense quadratic bilevel programming problems with a selectable number of known global and local solutions. The technique described here does not require the solution of any subproblems. In addition, since most techniques for solving these problems begin by solving the corresponding relaxed quadratic program, the global solutions are constructed to be different than the global solution of this relaxed problem in a selectable number of upper and lowerlevel variables. Finally, the problems that are generated satisfy the requirements imposed by all of the solution techniques known to the authors.

Baboulin, Marc; Buttari, Alfredo; Dongarra, Jack; Kurzak, Jakub; Langou, Julie; Langou, Julien; Luszczek, Piotr; Tomov, Stanimire
http://www.sciencedirect.com/science/article/B6TJ54TX79761/2/a85cf5566583a3c10996c05925efa9c9

Costa, Liliana; Fonseca, C. M. da; Martins, Enide Andrade
http://www.sciencedirect.com/science/article/B6V0R4V5GD2H1/2/5a4ab2f05e5a55a500bf0fc93554003a

Rollinson, Sara; Rizzu, Patrizia; Sikkink, Stephen; Baker, Matthew; Halliwell, Nicola; Snowden, Julie; Traynor, Bryan J.; Ruano, Dina; Cairns, Nigel; Rohrer, Jonathan D.; Mead, Simon; Collinge, John; Rossor, Martin; Akay, Ela; Guerreiro, Rita; Rademakers, Rosa; Morrison, Karen E.; Pastor, Pau; Alonso, Elena; MartinezLage, Pablo; GraffRadford, Neil; Neary, David; Heutink, Peter; Mann, David M. A.; Swieten, John Van; PickeringBrown, Stuart M.
http://www.sciencedirect.com/science/article/B6T094VKMW0R1/2/c38ac7e3dcb87f1e42d35a151a3f69b2

Arcoya, David; Carmona, José; Leonori, Tommaso; MartínezAparicio, Pedro J.; Orsina, Luigi; Petitta, Francesco
http://www.sciencedirect.com/science/article/B6WJ24VKMWDR2/2/f35680f147d63f6297e97ebb1b4b242e

Barbeiro, S.; Ferreira, J. A.
http://www.sciencedirect.com/science/article/B6V294VM43XG1/2/493993c9687e5ff240f132118604a862