330 research outputs found

    Integer programming models for the pre-marshalling problem

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    [EN] The performance of shipping companies greatly depends on reduced berthing times. The trend towards bigger ships and shorter berthing times places severe stress on container terminals, which cannot simply increase the available cranes indefinitely. Therefore, the focus is on optimizing existing resources. An effective way of speeding up the loading/unloading operations of ships at the container terminal is to use the idle time before the arrival of a ship for sorting the stored containers in advance. The pre-marshalling problem consists in rearranging the containers placed in a bay in the order in which they will be required later, looking for a sequence with the minimum number of moves. With sorted bays, loading/unloading operations are significantly faster, as there is no longer a need to make unproductive moves in the bays once ships are berthed. In this paper, we address the pre-marshalling problem by developing and testing integer linear programming models. Two alternative families of models are proposed, as well as an iterative solution procedure that does not depend on a difficult to obtain upper bound. An extensive computational analysis has been carried out over several well-known datasets from the literature. This analysis has allowed us to test the performance of the models, and to conclude that the performance of the best proposed model is superior to that of previously published alternatives.This study has been partially supported by the Spanish Ministry of Education, Culture, and Sport, FPU Grant A-2015-12849 and by the Spanish Ministry of Economy and Competitiveness, under projects DPI2014-53665-P and DPI2015-65895-R, partially financed with FEDER funds.Parreño-Torres, C.; Alvarez-Valdes, R.; Ruiz García, R. (2019). Integer programming models for the pre-marshalling problem. European Journal of Operational Research. 274(1):142-154. https://doi.org/10.1016/j.ejor.2018.09.048S142154274

    Estudio sobre el grado de conocimiento sobre las drogas de diseño en la UJI

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    Cinquenes Jornades de Foment de la Investigació de la FCHS (Any 1999-2000

    Numerical precision radiative corrections to the Dalitz plot of baryon semileptonic decays including the spin-momentum correlation of the decaying and emitted baryons

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    We calculate the radiative corrections to the angular correlation between the polarization of the decaying and the direction of the emitted spin one-half baryons in the semileptonic decay mode. The final results are presented, first, with the triple integration of the bremsstrahlung photon ready to be performed numerically and, second, in an analytical form. A third presentation of our results in the form of numerical arrays of coefficients to be multiplied by the quadratic products of form factors is discussed. This latter may be the most practical one to use in Monte Carlo simulations. A series of crosschecks is performed. Previous results to order (alpha/pi)(q/M_1) for the decays of unpolarized baryons are reviewed, too, where q is the momentum transfer and M_1 is the mass of the decaying baryon. This paper is self-contained and organized to make it accessible and reliable in the analysis of the Dalitz plot of precision experiments involving heavy quarks and is not compromised to fixing the form factors at predetermined values. It is assumed that the real photons are kinematically discriminated. Otherwise, our results have a general model-independent applicability.Comment: 34 pages, 4 tables, no figures. Some sections have been shortened. Conclusions remain unchange

    EvalGRAPHs: herramienta para implementar evaluadores inteligentes. Metodología de estudio del comportamiento de los evaluadores

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    El Modelo Granular Lingüístico de la Evaluación del aprendizaje humano ha sido desarrollado a partir del paradigma GLMP, basado en la computación con palabras y percepciones, con el objetivo de diseñar un modelo teórico de representación del aprendizaje que pueda aplicarse a la creación de sistemas (GLMPs) que emulen la evaluación realizada por un profesor, en base a sus criterios, y expresen dicha evaluación mediante un informe en lenguaje natural. Un GLMP es una estructura jerárquica que organiza y procesa datos mediante inferencia borrosa y modela un fenómeno mediante percepciones o unidades de conocimiento. Estos sistemas utilizan como datos de entrada los generados automáticamente por un entorno de aprendizaje y producen como salida un informe de evaluación que incluye una calificación numérica. De esta manera se puede compaginar la evaluación formativa, comparando logros y objetivos de aprendizaje, que realiza un profesor, con la rapidez y eficacia de un sistema automatizado. Como aplicación del modelo general, hemos diseñado varios sistemas que evalúan, en base a criterios de un profesor, unos los quizzes de Moodle y otros las simulaciones visuales de algoritmos de grafos hechas en el entorno de aprendizaje GRAPHs

    A branch and bound approach for large pre-marshalling problems

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    [EN] The container pre-marshalling problem involves the sorting of containers in stacks so that there are no blocking containers and retrieval is carried out without additional movements. This sorting process should be carried out in as few container moves as possible. Despite recent advancements in solving real world sized problems to optimality, several classes of pre-marshalling problems remain difficult for exact approaches. We propose a branch and bound algorithm with new components for solving such difficult instances. We strengthen existing lower bounds and introduce two new lower bounds that use a relaxation of the pre-marshalling problem to provide tight bounds in specific situations. We introduce generalized dominance rules that help reduce the search space, and a memoization heuristic that finds feasible solutions quickly. We evaluate our approach on standard benchmarks of pre-marshalling instances, as well as on a new dataset to avoid overfitting to the available data. Overall, our approach optimally solves many more instances than previous work, and finds feasible solutions on nearly every problem it encounters in limited CPU times.The authors thank the Paderborn Center for Parallel Computation (PC2) for the use of the Arminius cluster for the computational study in this work. This work has been partially supported by the Spanish Ministry of Science, Innovation, and Universities FPU Grant A-2015-12849 and by the Spanish Ministry of Economy and Competitiveness, under projects DPI2014-53665-P and DPI2015-65895-R, partially financed with FEDER funds.Tanaka, S.; Tierney, K.; Parreño-Torres, C.; Alvarez-Valdes, R.; Ruiz García, R. (2019). A branch and bound approach for large pre-marshalling problems. European Journal of Operational Research. 278(1):211-225. https://doi.org/10.1016/j.ejor.2019.04.005S211225278

    Radiative corrections to all charge assignments of heavy quark baryon semileptonic decays

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    In semileptonic decays of spin-1/2 baryons containing heavy quarks up to six charge assignments for the baryons and lepton are possible. We show that the radiative corrections to four of these possibilities can be directly obtained from the final results of the two possibilities previously studied. There is no need to recalculate integrals over virtual or real photon momentum or any traces.Comment: 15 pages, 2 figures, RevTex. Extended discussion. Final version to appear in Physical Review

    Snail1 induces IL-17 expression to inhibit adipogenesis

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    44 p.-7 fig.-1 tab. Peláez-García, Alberto et al.Adipogenesis requires a differentiation program driven by multiple transcription factors, where PPARγ and C/EBPα play a central role. Recent findings indicate that Snail inhibits adipocyte differentiation in 3T3-L1 and murine mesenchymal stem cells (mMSC). An in-depth quantitative SILAC analysis of the nuclear fraction of Snail-induced alterations of 3T3-L1 cells was carried out. In total, 2251 overlapping proteins were simultaneously quantified in forward and reverse experiments. We observed 574 proteins deregulated by Snail1 using a fold-change ≥1.5, with 111 up- and 463 down-regulated proteins, respectively. Among other proteins, multiple transcription factors such as Trip4, OsmR, Nr2f6, Cbx6, and Prrx1 were down-regulated. Results were validated in 3T3-L1 cells and mMSC cells by Western blot and quantitative PCR. Knock-down experiments in 3T3-L1 cells demonstrated that only Nr2f6 (and Trip4 at minor extent) was required for adipocyte differentiation. Ectopic expression of Nr2f6 reversed the effects of Snail1 and promoted adipogenesis. Because Nr2f6 inhibits the expression of IL-17, we tested the effect of Snail on IL-17 expression. IL-17 and TNFα were among the most up-regulated pro-inflammatory cytokines in Snail-transfected 3T3-L1 and mMSC cells. Furthermore, the blocking of IL-17 activity in Snail-transfected cells promoted adipocyte differentiation, reverting Snail inhibition. In summary, Snail inhibits adipogenesis through a down-regulation of Nr2f6, which in turn facilitates the expression of IL-17, an anti-adipogenic cytokine. These results would support a novel and important role for Snail and Nr2f6 in obesity control.This research was supported by a grant to established research groups (AECC), grant BIO2012-31023 from the Ministry of Economy and Competitiveness, grant S2011/BMD-2344/ (Colomics2) from Comunidad de Madrid and ProteoRed-ISCIII support. Work at AGH’s lab was supported by a grant from the Ministry of Economy and Competitiveness (SAF2010-16089)Peer reviewe

    Economic Valuation of Cultural Heritage: Application of Travel Cost Method to the National Museum and Research Center of Altamira

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    The economic assessment of non-marketed resources (i.e., cultural heritage) can be developed with stated or revealed preference methods. Travel cost method (TCM) is based on the demand theory and assumes that the demand for a recreational site is inversely related to the travel costs that a certain visitor must face to enjoy it. Its application requires data about the tourist?s origin. This work aims to analyze the economic value of the National Museum and Research Center of Altamira, which was created to research, conserve, and broadcast the Cave of Altamira (UNESCO World Heritage Site since 1985). It includes an accurate replica known as the ?Neocave?. Two different TCM approaches have been applied to obtain the demand curve of the museum, which is a powerful tool that helps to assess past and future investments. It has also provided the annual economic value estimate of the National Museum and Research Center of Altamira, which varies between 4.75 and 8.00 million € per ye
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