3 research outputs found
Development of hybrid metaheuristics based on instance reduction for combinatorial optimization problems
Get PDF113 p.La tesis presentada describe el desarrollo de algoritmos metaheur铆sticos h铆bridos, basados en reducci贸n de instancias de problema. 脡stos son enfocados en la resoluci贸n de problemas de optimizaci贸n combinatorial. La motivaci贸n original de la investigaci贸n radic贸 en lograr, a trav茅s de la reducci贸n de instancias de problemas, el uso efectivo de modelos de programaci贸n lineal entera (ILP) sobre problemas que dado su tama帽o no admiten el uso directo con esta t茅cnica exacta. En este contexto se presenta entre otros desarrollos el framework Construct, Merge, Solve & Adapt (CMSA) para resoluci贸n de problemas de optimizaci贸n combinatorial en general, el cual posteriormente fue adaptado para mejorar el desempe帽o de otras metaheur铆sticas sin el uso de modelos ILP. Los algoritmos presentados mostraron resultados que compiten o superan el estado del arte sobre los problemas Minimum Common String Partition (MCSP), Minimum Covering Arborescence (MCA) y Weighted Independent Domination (WID)
Development of hybrid metaheuristics based on instance reduction for combinatorial optimization problems
Get PDF113 p.La tesis presentada describe el desarrollo de algoritmos metaheur铆sticos h铆bridos, basados en reducci贸n de instancias de problema. 脡stos son enfocados en la resoluci贸n de problemas de optimizaci贸n combinatorial. La motivaci贸n original de la investigaci贸n radic贸 en lograr, a trav茅s de la reducci贸n de instancias de problemas, el uso efectivo de modelos de programaci贸n lineal entera (ILP) sobre problemas que dado su tama帽o no admiten el uso directo con esta t茅cnica exacta. En este contexto se presenta entre otros desarrollos el framework Construct, Merge, Solve & Adapt (CMSA) para resoluci贸n de problemas de optimizaci贸n combinatorial en general, el cual posteriormente fue adaptado para mejorar el desempe帽o de otras metaheur铆sticas sin el uso de modelos ILP. Los algoritmos presentados mostraron resultados que compiten o superan el estado del arte sobre los problemas Minimum Common String Partition (MCSP), Minimum Covering Arborescence (MCA) y Weighted Independent Domination (WID)
Rovibronic signatures of molecular aggregation in the gas phase: subtle homochirality trends in the dimer, trimer and tetramer of benzyl alcohol.
Get PDF[EN]Molecular aggregation is of paramount importance in many chemical processes, including those in living beings. Thus, characterization of the intermolecular interactions is an important step in its understanding. We describe here the aggregation of benzyl alcohol at the molecular level, a process governed by a delicate equilibrium between OHMIDLINE HORIZONTAL ELLIPSISO and OHMIDLINE HORIZONTAL ELLIPSIS pi hydrogen bonds and dispersive interactions. Using microwave, FTIR, Raman and mass-resolved double-resonance IR/UV spectroscopic techniques, we explored the cluster growth up to the tetramer and found a complex landscape, partly due to the appearance of multiple stereoisomers of very similar stability. Interestingly, a consistently homochiral synchronization of transiently chiral monomer conformers was observed during cluster growth to converge in the tetramer, where the fully homochiral species dominates the potential energy surface. The data on the aggregation of benzyl alcohol also constitute an excellent playground to fine-tune the parameters of the most advanced functionals.The Gottingen part of the project was partly funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - 271107160/SPP1807. We thank M. Lange and E. K. M. M. Sennert for the measurement of the FTIR spectrum and E. Meyer for help with the measurement of the Raman spectrum. Computational resources from the GWDG and the Gottingen Faculty of Chemistry (DFG - 405832858/INST 186/1294-1 FUGG) are acknowledged. We thank the Gottingen chemistry workshops for valuable support. This publication was supported financially by the Open Access Grant Program of the DFG and the Open Access Publication Fund of the University of Gottingen. The Bilbao and Valladolid groups acknowledge funding from the Spanish Ministerio de Ciencia e Innovacion (MICINN-FEDER PGC2018-098561-B-C21 and PGC2018-098561-B-C22). Bilbao's group also thank the SGIKER (UPV/EHU, MICIU-FEDER) for the computational and laser resources. The Hamburg part of this work was financially supported by the Deutsche Forschungsgemeinschaft (SCHN1280/4-2, project number 271359857) in the context of the priority program SPP 1807 "Control of London dispersion interactions in molecular chemistry". P. Pinacho would like to thank the Alexander von Humboldt Foundation for a postdoctoral fellowship
