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Detalhes

004
Publicações

2020

A comparison of matching algorithms for kidney exchange programs addressing waiting time

Autores
Monteiro, T; Klimentova, X; Pedroso, JP; Viana, A;

Publicação
Central European Journal of Operations Research

Abstract

2019

Maximizing the expected number of transplants in kidney exchange programs with branch-and-price

Autores
Alvelos, F; Klimentova, X; Viana, A;

Publicação
Annals of Operations Research

Abstract
In this paper, we propose a branch-and-price approach for solving the problem of maximizing the expected number of transplants in Kidney Exchange Programs (KEPs). In these programs, the decision on which transplants will be conducted is usually made with the support of optimization models with the assumption that all operations will take place. However, after a plan of transplants is defined, a pair may leave the KEP or a more accurate compatibility evaluation exam may invalidate a transplant. To model these possible events we consider probabilities of failure of vertices and of arcs and the objective of maximizing the expected number of transplants. The proposed approach is based on the so-called cycle formulation, where decision variables are associated with cycles. Built on the concept of type of cycle a branch-and-price algorithm is conceived. One subproblem is defined for each type of cycle. We present computational results of the proposed branch-and-price algorithm and compare them with solving directly the cycle formulation (with a general purpose mixed integer programming solver—CPLEX) showing that the proposed approach is the only one suitable for larger instances. © 2017 Springer Science+Business Media, LLC

2019

Modelling and optimisation in European Kidney Exchange Programmes

Autores
Biró, P; van de Klundert, J; Manlove, D; Pettersson, W; Andersson, T; Burnapp, L; Chromy, P; Delgado, P; Dworczak, P; Haase, B; Hemke, A; Johnson, R; Klimentova, X; Kuypers, D; Nanni Costa, A; Smeulders, B; Spieksma, F; Valentín, MO; Viana, A;

Publicação
European Journal of Operational Research

Abstract
The complex multi-criteria optimisation problems arising in Kidney Exchange Programmes have received considerable attention both in practice and in the scientific literature. Whereas theoretical advancements are well reviewed and synthesised, this is not the case for practice. We present a synthesis of models and methods applied in present European Kidney Exchange Programmes, which is based on detailed descriptions we created for this purpose. Most descriptions address national programmes, yet we also present findings on emerging cross-national programmes. The synthesis provides a systematic and detailed description of the models and methods the programmes use, revealing important commonalities as well as considerable variation among them. Rather than distilling a single best practice from these results, we find that the variation in models and methods arises because of variation in country characteristics, policies, and ethics. The synthesised state of the art may benefit future national and cross-national initiatives and direct future theoretical contributions within and across the boundaries of the Operations Research discipline. © 2019

2018

Observability of power systems with optimal PMU placement

Autores
Carvalho, M; Klimentova, X; Viana, A;

Publicação
Computers & Operations Research

Abstract

2018

Bi-level and Bi-objective p-Median Type Problems for Integrative Clustering: Application to Analysis of Cancer Gene-Expression and Drug-Response Data

Autores
Ushakov, AV; Klimentova, X; Vasilyev, I;

Publicação
IEEE/ACM Transactions on Computational Biology and Bioinformatics

Abstract