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An ACO-RFD hybrid method to solve NP-complete problems

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Frontiers of Computer Science 2013年第5期7卷 729-744页

作者： pablo RABANAL Ismael RODRIGUEZ Fernando RUBIO Dept. Sistemas Inforrnaiticos y Computacion Facultad de Informatica Universidad Complutense de Madrid Madrid 28040 Spain

In this paper we hybridize ant colony optimiza- tion （ACt） and river formation dynamics （RFD）, two related swarm intelligence methods. In ACt, ants form paths （prob- lem solutions） by following each other＇s pheromone trails and reinforcing trails at best paths until eventually a single path is followed. On the other hand, RFD is based on copy- ing how drops form rivers by eroding the ground and de- positing sediments. In a rough sense, RFD can be seen as a gradient-oriented version of ACt. Several previous experi- ments have shown that the gradient orientation of RFD makes this method solve problems in a different way as ACt. In particular, RFD typically performs deeper searches, which in turn makes it find worse solutions than ACt in the first exe- cution steps in general, though RFD solutions surpass ACt solutions after some more time passes. In this paper we try to get the best features of both worlds by hybridizing RFD and ACt. We use a kind of ant-drop hybrid and consider both pheromone trails and altitudes in the environment. We apply the hybrid method, as well as ACt and RFD, to solve two NP-hard problems where ACt and RFD fit in a different manner： the traveling salesman problem （TSP） and the prob- lem of the minimum distances tree in a variable-cost graph （MDV）. We compare the results of each method and we an- alyze the advantages of using the hybrid approach in each case.

关键词： river formation dynamics ant colony optimization heuristic algorithms NP-hard problems

Parallel array with axially coded light-sheet microscope

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Light(Science & Applications) 2020年第1期9卷 1387-1388页

作者： pablo Loza-Alvarez ICFO-The Institute of Photonic Sciences The Barcelona Institute of Science and Technology08860 CastelldefelsBarcelonaSpain

A parallel array of frequency modulated light sheets results in a scanning-less light sheet microscope capable of fast volumetric imaging.

关键词： array light axial

Recent advances in graphene and other 2D materials

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Nano Materials Science 2022年第1期4卷 3-9页

作者： pablo Ares Kostya S.Novoselov Department of Physics&Astronomy and National Graphene Institute University of ManchesterManchesterM139PLUK Centre for Advanced 2D Materials National University of Singapore117546Singapore Chongqing 2D Materials Institute Lingjiang New Area Chongqing 400714China

The isolation of the first two-dimensional material, graphene-a monolayer of carbon atoms arranged in a hexagonal lattice-opened new exciting opportunities in the field of condensed matter physics and materials. Its isolation and subsequent studies demonstrated that it was possible to obtain sheets of atomically thin crystals and that these were stable, and they also began to show its outstanding properties, thus opening the door to a whole new family of materials, known as two-dimensional materials or 2D materials. The great interest in different 2D materials is motivated by the variety of properties they show, being candidates for numerous ***, the combination of 2D crystals allows the assembly of composite, on-demand materials, known as van der Waals heterostructures, which take advantage of the properties of those materials to create functionalities that otherwise would not be accessible. For example, the combination of 2D materials, which can be done with high precision, is opening up opportunities for the study of new challenges in fundamental physics and novel applications. Here we review the latest fundamental discoveries in the area of 2D materials and offer a perspective on the future of the field.

关键词： 2D materials Graphene Molybdenum disulphide Tarition mebl dichalogenides Hexagonal boron nitride van der waals heterostructus Ulrathin nanomaterials

Bridging Methods for Atomistic-to-Continuum Coupling and Their Implementation

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Communications in Computational Physics 2010年第4期7卷 831-876页

作者： pablo Seleson Max Gunzburger Department of Scientific Computing Florida State UniversityTallahasseeFL 32306-4120USA

Several issues connected with bridging methods for atomistic-to-continuum(AtC)coupling are *** coupling approaches using various energy blending models are studied as well as the influence that model parameters,blending functions,and grids have on simulation *** use the Lagrange multiplier method for enforcing constraints on the atomistic and continuum displacements in the bridge *** also show that continuum models are not appropriate for dealing with problems with singular loads,whereas AtC bridging methods yield correct results,thus justifying the need for a multiscale *** investigate models that involve multiple-neighbor interactions in the atomistic region,particularly focusing on a comparison of several approaches for dealing with Dirichlet boundary conditions.

关键词： Multiscale modeling atomistic-to-continuum coupling boundary treatment

Diffusion dynamics and characterization of attogram masses in optically trapped single nanoparticles using laser-induced plasma imaging

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Nano Research 2023年第5期16卷 7470-7480页

作者： pablo Purohit Francisco J.Fortes Javier Laserna UMALASERLAB Departamento de Química AnalíticaUniversidad de MálagaC/Jiménez Fraud 4Malaga 29010Spain Niels Bohr Institute University of CopenhagenBlegdamsvej 172100 CopenhagenDenmark

In the present work,a wavelength-selected plasma imaging analysis system is presented and used to track photons emitted from single-trapped nanoparticles in air at atmospheric *** isolated nanoentities were atomized and excited into plasma state using single nanosecond laser *** use of appropriate wavelength filters alongside time-optimized acquisition settings enabled the detection of molecular and atomic emissions in the *** photon detection efficiency of the imaging line resulted in a signal>400 times larger than the simultaneously-acquired dispersive spectroscopy *** increase in sensitivity outlined the evolution of diverse physicochemical processes at the single particle scale which included heat and momentum transfer from the plasma into the particle as wells as chemical *** imaging detection of excited fragments evidenced different diffusion kinetics and time frames for atoms and molecules and their influence upon both the spectroscopic emission readout and fabrication processes using the plasma as a ***,the origin of molecular species,whether naturally-occurring or derived from a chemical reaction in the plasma,could also be studied on the basis of compositional gradients found on the *** of detection for the inspected species ranged from tens to hundreds attograms,thus leading to an exceptional sensing principle for single nanoentities that may impact several areas of science and technology.

关键词： single nanoparticle inspection wavelength-selected laser-induced plasma imaging laser fabrication attogram characterization atomic/molecular diffusion

Editorial for a special issue on graphene and 2D alternative materials:From preparation to potential applications

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Nano Materials Science 2022年第1期4卷 1-2页

作者： pablo Ares Felix Zamora Departamento de Fisica de la Materia Condensada and Condensed Matter Physics Center(IFIMAC) Universidad Autonoma de Madrid Madrid28049Spain Departamento de Quimica Inorganica Condensed Matter Physics Center(IFIMAC)and Institute for Advanced Research in Chemical Sciences(IAdChem)Universidad Autonoma de MadridMadrid28049Spain Instituto Madrileno de Estudios Avanzados en Nanociencia(IMDEA-Nanociencia) CantoblancoMadrid28049Spain

The isolation of graphene and subsequent studies showed that obtaining atomically thin crystalline sheets was feasible and possessed extraordinary *** result opened the door to an entirely new family of materials known as two-dimensional or 2D *** in this field is intense:the emergence of new 2D materials,the properties of their combinations and the ability of graphene to reinvent itself,showing novel and exciting properties,make it likely that this field will continue to be one of the leading topics of materials science and condensed matter physics.

关键词： preparation entirely crystalline

Marriage Market with Indifferences: A Linear Programming Approach

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Journal of the Operations Research Society of China 2023年第1期11卷 219-242页

作者： Noelia Juarez pablo A.Neme Jorge Oviedo Instituto de Matemática Aplicada San Luis IMASLRedNIEUniversidad Nacional de San Luis and CONICETD5700HHWSan LuisRepublica Argentina

We study stable and strongly stable matchings in the marriage market with indifference in their *** characterize the stable matchings as integer extreme points of a convex *** give an alternative proof for the integrity of the strongly stable matching ***,we compute men-optimal(women-optimal)stable and strongly stable matchings using linear *** preferences are strict,we find the men-optimal(women-optimal)stable matching.

关键词： Matching markets The marriage market with indifferences Optimal stable matchings Linear programming

On fixity of arc-transitive graphs

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Science China Mathematics 2021年第12期64卷 2603-2610页

作者： Florian Lehner Primoz Potocnik pablo Spiga Institute of Discrete Mathematics Graz University of TechnologyGraz 8010Austria Faculty of Mathematics and Physics University of LjubljanaLjubljana 1000Slovenia Dipartimento di Matematica Pura e Applicata University of Milano-BicoccaMilano 20126Italy

The relative xity of a permutation group is the maximum proportion of the points xed by a non-trivial element of the group,and the relative xity of a graph is the relative xity of its automorphism group,viewed as a permutation group on the vertex-set of the *** prove in this paper that the relative xity of connected 2-arc-transitive graphs of a xed valence tends to 0 as the number of vertices grows to in *** prove the same result for the class of arc-transitive graphs of a xed prime valence,and more generally,for any class of arc-transitive locally-L graphs,where L is a xed quasiprimitive graph-restrictive permutation group.

关键词： permutation group xity minimal degree graph automorphism group vertex-transitive arc-transitive xed points

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NHC-catalysed[3+2]-asymmetric annulation between pyrazolin-4,5-diones and enals:synthesis of novel spirocyclic pyrazolone γ-butyrolactones and computational study of mechanism and stereoselectivity

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Organic Chemistry Frontiers 2022年第2期9卷 420-427页

作者： Marta Gil-Ordonez Alicia Maestro pablo Ortega pablo G.Jambrina Jose M.Andres GIR-SintACat-Instituto Universitario CINQUIMA y Departamento de Química Orgánica Facultad de CienciasUniversidad de ValladolidPaseo Belén 747011 ValladolidSpain Departamento de Química Física University of Salamanca37008 SalamancaSpain

Chiral pyrazolones with a spirocyclic centre at the C4-position are widely found in a large family of medically relevant *** recent years,organocatalysis,particularly that performed with quiral N-heterocyclic carbenes(NHCs),has allowed the enantioselective synthesis of these spirocyclic compounds despite its inherent *** this work,we describe the fully diastereo-and highly enantioselective synthesis of novel spirocyclic pyrazolone γ-butyrolactones via NHC-catalysed[3+2]annulation reaction of enals and 1H-pyrazol-4,*** understand the catalytic mechanism and origin of stereoselectivity,electronic structure calculations were carried *** considering various pathways,we concluded that the stereoselectivity-determining step is the formation of the lactone that proceeds after addition of the NHC derived homoenolate to the electrophilic carbonyl group of pyrazolin-4,*** calculations predict that the free energy barrier is lower for the(RS)product,which is also the main product experimentally obtained.

关键词： synthesis spiro mechanism