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Your search keyword '"Cancela, Héctor"' showing total 258 results
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258 results on '"Cancela, Héctor"'

1. Understanding the changes induced by the incorporation of trees in low densities into livestock systems: relevance of a long-term interdisciplinary experimental platform

Author

Fedrigo, Jean K., Benítez, Valentina, de Souza, Mauricio, Morales, Virginia, Piñeyro, Pedro, Viana, Víctor, Blumetto, Oscar, Cancela, Héctor, Bertoncelli, Patricia, Laufer, Gabriel, González-Barrios, Pablo, Siri, Paulina, Báez, Francisco, García, Luís, Ciganda, Verónica, Pravia, Virginia, and Viñoles, Carolina

Published
2024
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2. Analysis and Reliability of Separable Systems

Author

Cancela, Héctor, Guerberoff, Gustavo, Robledo, Franco, and Romero, Pablo

Subjects
Computer Science - Discrete Mathematics, Electrical Engineering and Systems Science - Systems and Control
Abstract

The operation of a system, such as a vehicle, communication network or automatic process, heavily depends on the correct operation of its components. A Stochastic Binary System (SBS) mathematically models the behavior of on-off systems, where the components are subject to probabilistic failures. Our goal is to understand the reliability of the global system. The reliability evaluation of an SBS belongs to the class of NP-Hard problems, and the combinatorics of SBS imposes several challenges. In a previous work by the same authors, a special sub-class of SBSs called "separable systems" was introduced. These systems accept an efficient representation by a linear inequality on the binary states of the components. However, the reliability evaluation of separable systems is still hard. A theoretical contribution in the understanding of separable systems is given. We fully characterize separable systems under the all-terminal reliability model, finding that they admit efficient reliability evaluation in this relevant context.

Published
2020

3. A hybrid optimization procedure for solving a tire curing scheduling problem

Author

Velázquez, Joaquín, Cancela, Héctor, and Piñeyro, Pedro

Subjects
Computer Science - Artificial Intelligence, 90B35, 90B30
Abstract

This paper addresses a lot-sizing and scheduling problem variant arising from the study of the curing process of a tire factory. The aim is to find the minimum makespan needed for producing enough tires to meet the demand requirements on time, considering the availability and compatibility of different resources involved. To solve this problem, we suggest a hybrid approach that consists in first applying a heuristic to obtain an estimated value of the makespan and then solving a mathematical model to determine the minimum value. We note that the size of the model (number of variables and constraints) depends significantly on the estimated makespan. Extensive numerical experiments over different instances based on real data are presented to evaluate the effectiveness of the hybrid procedure proposed. From the results obtained we can note that the hybrid approach is able to achieve the optimal makespan for many of the instances, even large ones, since the results provided by the heuristic allow to reduce significantly the size of the mathematical model.

Published
2020

6. Public Transportation

Author

Mauttone, Antonio, Cancela, Héctor, Urquhart, María E., Crainic, Teodor Gabriel, editor, Gendreau, Michel, editor, and Gendron, Bernard, editor

Published
2021
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7. On the number of open knight's tours

Author

Cancela, Héctor and Mordecki, Ernesto

Subjects
Mathematics - Combinatorics, 05C30
Abstract

We review the state of the art in the problem of counting the number open knight tours, since the publication in internet of a computation of this quantity., Comment: 3 pages

Published
2015

10. Understanding the changes induced by the incorporation of trees in low densities into livestock systems: relevance of a long-term interdisciplinary experimental platform

Author

Fedrigo, Jean K., primary, Benítez, Valentina, additional, de Souza, Mauricio, additional, Morales, Virginia, additional, Piñeyro, Pedro, additional, Viana, Víctor, additional, Blumetto, Oscar, additional, Pravia, Virginia, additional, Ciganda, Verónica, additional, Cancela, Héctor, additional, Bertoncelli, Patricia, additional, Laufer, Gabriel Laufer, additional, Barrios, Pablo González, additional, Siri, Paulina, additional, Báez, Francisco, additional, García, Luis Fernando, additional, and Gil, Carolina Viñoles, additional

Published
2024
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12. Special Issue on "Agricultural E‐commerce and Logistics Operations in the Era of Digital Economy".

Author

Bian, Yiwen, Chen, Jing, Guan, Xu, Han, Xiaohua, and Cancela, Héctor

Subjects
AGRICULTURAL economics, SUSTAINABLE agriculture, FARM management, SUPPLY chain management, DIGITAL technology
Abstract

The special issue of "International Transactions in Operational Research" focuses on the theme of "Agricultural E-commerce and Logistics Operations in the Era of Digital Economy." It highlights the challenges and opportunities faced by developing economies like China and India in enhancing the efficiency and sustainability of agricultural operations. The rapid growth of e-commerce has significantly improved the connection between farmers and consumers, but also brought about challenges such as quality control and logistics issues. The adoption of digital intelligence technologies like AI, IoT, and blockchain offers solutions to these challenges, increasing farmers' incomes, providing fresher products, and reducing resource waste and pollution. The special issue invites research articles exploring how digital technologies create business value for various stakeholders in the agricultural sector. [Extracted from the article]

Published
2025
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13. Counting Knight's Tours through the Randomized Warnsdorff Rule

Author

Cancela, Héctor and Mordecki, Ernesto

Subjects
Mathematics - Probability, Mathematics - Combinatorics
Abstract

We give an estimate of the number of geometrically distinct open tours $\G$ for a knight on a chessboard. We use a randomization of Warnsdorff rule to implement importance sampling in a backtracking scheme, correcting the observed bias of the original rule, according to the proposed principle that ``most solutions follow Warnsdorff rule most of the time''. After some experiments in order to test this principle, and to calibrate a parameter, interpreted as a distance of a general solution from a Warnsdorff solution, we conjecture that $\G=1.22\times 10^{15}$., Comment: 8 pages. See also http://www.cmat.edu.uy/~mordecki/articles

Published
2006

19. Diameter constrained reliability of ladders and Spanish fans

Author

Cancela Héctor, Robledo Franco, Romero Pablo, and Sartor Pablo

Subjects
diameter constrained reliability, computational complexity, graph theory, Management information systems, T58.6-58.62
Abstract

We are given a graph G = (V, E), terminal set K  V and diameter d > 0. Links fail stochastically and independently with known probabilities. The diameter-constrained reliability (DCR for short), is the probability that the K-diameter is not greater than d in the subgraph induced by non-failed links. The contributions of this paper are two-fold. First, the computational complexity of DCR-subproblems is discussed in terms of the number of terminals k = jKj and diameter d. Here, we prove that when d > 2 the problem is NP-Hard when K = V. Second, we compute the DCR efficiently for Ladders and Spanish Fans. Open problems and trends for future work are discussed in the conclusions.

Published
2016
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25. Modelling the forest harvesting tour problem.

Author

Viana, Víctor, Cancela, Héctor, and Pradenas, Lorena

Subjects
LOGGING, FOREST management, HARVESTING, HARVESTING equipment, COMBINATORIAL optimization, MATHEMATICAL programming
Abstract

In a globalized market, forest management plans play an important role in the sustainability of forest enterprises. Several optimization processes have therefore been developed to support decision-making in forestry operations. However, important issues remain to be addressed, such as planning the allocation of harvesting areas and scheduling the harvesting teams that are contracted for these purposes. Harvesting schedules include different time scales and natural constraints, so that finding optimal or even good quality ones constitutes a highly complex combinatorial optimization problem. Efficient planning of harvesting operations can significantly reduce the costs associated with logistics and improve the economic performance of companies in the sector. In Uruguay, almost 75% of total forest harvesting operations for pulp production are carried out by contractor companies, so they are an important player in the supply chain. This study aims to optimize the allocation and routing of the harvesting equipment of forest contractors, which must be located at the sites to be harvested during the year. Numerical experiments over a case study based on realistic data have shown that realistic-sized instances can be resolved by standard mathematical programming software in a reasonable time. The mathematical programming model can also be useful to evaluate potential gains in joint planning by several contractors with respect to the costs incurred by separate planning; as illustrated also with numerical examples over the same case study. This model can be used to support annual forest harvest scheduling and equipment allocation for corporate contractors, leading to better quality plans and improvement opportunities. [ABSTRACT FROM AUTHOR]

Published
2023
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30. On the Reliability Estimation of Stochastic Binary System

Author

Cancela, Héctor, Murray, Leslie, Robledo, Franco, Romero, Pablo, and Sartor, Pablo

Subjects
Splitting, Duality, Ciencias Naturales y Exactas, Matemáticas, Estadística y Probabilidad, Ciencias de la Computación e Información, Permutation Monte Carlo, Stochastic Binary Systems, System Reliability
Abstract

A stochastic binary system is a multi-component on-off system subject to random independent failures on its components. After potential failures, the state of the subsystem is ruled by a logical function (called structure function) that determines whether the system is operational or not. Stochastic binary systems (SBS) serve as a natural generalization of network reliability analysis, where the goal is to find the probability of correct operation of the system (in terms of connectivity, network diameter or different measures of success). A particular subclass of interest is stochastic monotone binary systems (SMBS), which are characterized by non-decreasing structure. We explore the combinatorics of SBS, which provide building blocks for system reliability estimation, looking at minimal non-operational subsystems, called mincuts. One key concept to understand the underlying combinatorics of SBS is duality. As methods for exact evaluation take exponential time, we discuss the use of Monte Carlo algorithms. In particular, we discuss the F-Monte Carlo method for estimating the reliability polynomial for homogeneous SBS, the Recursive Variance Reduction (RVR) for SMBS, which builds upon the efficient determination of mincuts, and three additional methods that combine in different ways the well--known techniques of Permutation Monte Carlo and Splitting. These last three methods are based on a stochastic process called Creation Process, a temporal evolution of the SBS which is static by definition. All the methods are compared using different topologies, showing large efficiency gains over the basic Monte Carlo scheme. Agencia Nacional de Investigación e Innovación Math-AMSUD

Published
2021

40. Preface

Author

Cancela, Héctor, primary, Marín, Gabriela, additional, and Villarreal, Vladimir, additional

Published
2020
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42. On the reliability estimation of stochastic binary systems.

Author

Cancela, Héctor, Murray, Leslie, Robledo, Franco, Romero, Pablo, and Sartor, Pablo

Subjects
STOCHASTIC systems, MONTE Carlo method, HOMOGENEOUS polynomials, STOCHASTIC processes, RELIABILITY in engineering
Abstract

A stochastic binary system (SBS) is a multicomponent on‐off system subject to random independent failures on its components. After potential failures, the state of the subsystem is ruled by a logical function (called structure function) that determines whether the system is operational or not. A SBS serves as a natural generalization of network reliability analysis, where the goal is to find the probability of correct operation of the system (in terms of connectivity, network diameter, or different measures of success). A particular subclass of interest is stochastic monotone binary systems (SMBS), which are characterized by nondecreasing structure. We explore the combinatorics of SBS, which provide building blocks for system reliability estimation, looking at minimal nonoperational subsystems, called mincuts. One key concept to understand the underlying combinatorics of SBS is duality. As methods for exact evaluation take exponential time, we discuss the use of Monte Carlo algorithms. In particular, we discuss the F‐Monte Carlo method for estimating the reliability polynomial for homogeneous SBS, the recursive variance reduction for SMBS, which builds upon the efficient determination of mincuts, and three additional methods that combine in different ways the well‐known techniques of permutation Monte Carlo and splitting. These last three methods are based on a stochastic process called the creation process, a temporal evolution of the SBS which is static by definition. All the methods are compared using different topologies, showing large efficiency gains over the basic Monte Carlo scheme. [ABSTRACT FROM AUTHOR]

Published
2022
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43. Splitting-Based Method for Network Reliability Estimation

Author

Cancela, Héctor, Murray, Leslie, Rubino, Gerardo, Instituto de Computacion [Montevideo] (INCO), Universidad de la República [Montevideo] (UCUR), Facultad de Ciencias Exactas, Ingenieria y Agrimensura [Rosario] (FCEIA), Universidad Nacional de Rosario [Santa Fe], Dependability Interoperability and perfOrmance aNalYsiS Of networkS (DIONYSOS), Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-RÉSEAUX, TÉLÉCOMMUNICATION ET SERVICES (IRISA-D2), Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Rennes 1 (UR1), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Universidad de la República [Montevideo] (UDELAR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique)

Subjects
[INFO.INFO-NI]Computer Science [cs]/Networking and Internet Architecture [cs.NI], [INFO.INFO-PF]Computer Science [cs]/Performance [cs.PF], [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2019

45. A multi-objective optimization model for dairy feeding management

Author

Notte, Gastón, Cancela, Héctor, Pedemonte, Martín, Chilibroste, Pablo, Rossing, Walter, Groot, Jeroen C.J., Notte, Gastón, Cancela, Héctor, Pedemonte, Martín, Chilibroste, Pablo, Rossing, Walter, and Groot, Jeroen C.J.

Abstract

The allocation of feedstuff to intensively managed dairy cows to achieve different objectives is challenging due to the inherent complexity of the system and the combinatorial problem that has to be solved. Pareto-based multi-objective optimization approaches using evolutionary algorithms can help to address these challenges and show the trade-offs and synergies among various objectives. Here we present a framework for multi-objective optimization with the Differential Evolution (DE) algorithm applied to dairy feeding systems with grazing and concentrate supply to generate an approximation of the Pareto front. The available feed resources are located in different feeding areas, and the number of animals and groups of animals with similar feeding requirements are distributed across these areas for feeding purposes. To evaluate the DE algorithm, we performed two in-silico experiments to: (1) compare the solutions quality of single-objective DE with exact Linear Programming (LP) solutions, and (2) assess the influence of different stocking rates (number of cows/ha) on milk production, feed allocation and economic performance indicators. The DE solutions that minimize the feeding costs for different stocking rates (1.1–2.6 cows/ha) closely approached the solutions derived with LP, confirming the quality of the heuristic algorithm. The multi-objective model scenarios demonstrated that increasing stocking density would enhance milk production and gross margin per unit of area at largely unchanged productivity per animal by shifting the feed ration from roughage to a large proportion of supplementary concentrate feed. At low stocking rates solutions with high productivity and gross margin and a large proportion of roughage in the ration and limited supplementary feeding were identified. We conclude that the multi-objective optimization with a Pareto-based DE algorithm is highly effective to explore the interrelations among conflicting objectives and to find suitable soluti

Published
2020

49. The Multi-Level Creation Process in Flow Network Reliability Estimation

Author

Cancela, Héctor, Murray, Leslie, Rubino, Gerardo, Instituto de Computacion [Montevideo] (INCO), Universidad de la República [Montevideo] (UCUR), Facultad de Ciencias Exactas, Ingenieria y Agrimensura [Rosario] (FCEIA), Universidad Nacional de Rosario [Santa Fe], Dependability Interoperability and perfOrmance aNalYsiS Of networkS (DIONYSOS), Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-RÉSEAUX, TÉLÉCOMMUNICATION ET SERVICES (IRISA-D2), Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Université de Bretagne Sud (UBS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National de Recherche en Informatique et en Automatique (Inria)-École normale supérieure - Rennes (ENS Rennes)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-CentraleSupélec-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Bretagne Sud (UBS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-École normale supérieure - Rennes (ENS Rennes)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Universidad de la República [Montevideo] (UDELAR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique)

Subjects
[INFO.INFO-PF]Computer Science [cs]/Performance [cs.PF], [MATH.MATH-ST]Mathematics [math]/Statistics [math.ST], [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2018

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