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Chinese Physics Letters 2003年第5期20卷 657-659页

作者： ZHANGXue-Mei GUOPan-Lin A.Gonzalez j.crespo AppliedIonBeamPhysicsLaboratory InstituteofModernPhysicsFudanUniversityShanghai200433 ShanghaiInstituteofNuclearResearch ChineseAcademyofSciencesShanghai201800 Max-Planck-InstitutfurKernphysik Saupfercheckweg1D-69117HeidelbergGermany

An experimental system for dielectronic recombination was set-up on H-EBIT in order to carry out dielectronic recombination study. Some preliminary results of He-like Ge32+ and Cu27+ are obtained. Space charge shift on determination of the resonance position for Ge32+ at 100mA is around 18% and that for Cu27+ is around 38%. Further analysis of experimental data is in progress.

关键词：实验研究二次电子再结合离子捕获电子束自由电子

Indirect determination of shear wave velocity in slow formations using full-wave sonic logging technique

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journal of Rock Mechanics and Geotechnical Engineering 2020年第6期12卷 1226-1233页

作者： Francisco Beltran Alvaro Yañez-Gonzalez María j.crespo Belgar Engineering Consultants Gabriel García Márquez 9Collado-Villalba28400Spain ESTEYCO Menéndez Pidal 17Madrid28036Spain Principia Engineering Consuxltants Velázquez 94Madrid28006Spain

This article presents a case study concerning a seismic characterization ***-wave sonic logging was used to characterize the shallow compressional wave and shear wave velocity profiles in the *** values of the Poisson’s ratio derived from the velocity profiles suggested that the boreholes might have traversed slow formations(*** shear wave velocity smaller than the borehole fluid compressional wave velocity or“mud-wave speed”)and that conventional processing of the sonic logs might have misinterpreted the direct arrivals of fluid acoustic waves as arrivals caused by shear wave propagation in the ***,the shear wave velocity profiles provided by the contractor were considered to be unreliable by the project *** address these problems,a non-conventional determination of the shear wave velocity was implemented,based on the relationship between the Poisson’s ratio of the rock formation and the shape of the first train of sonic waves which arrived to the receivers in the sonic *** relationship was determined based on several hundreds of finite element simulations of the acoustic wave propagation in boreholes with the same diameter as used in the *** present article describes how this non-conventional approach was developed and implemented to obtain the shear wave velocity profiles from the raw sonic *** approach allows an extension of the range of applicability of full-wave sonic logging to determination of shear wave velocity profiles in formations with low compressional wave *** method could be used to obtain shear wave velocity profiles where compressional wave velocity is as low as slightly larger than the mud-wave speed.A sample sonic log in Log ASCII Standard(LAS)format is provided as supplementary material to this paper via Mendeley Data,together with the FORTRAN source code used to process the log following the approach described in this study.

关键词： Sonic logging Slow formation Shear wave velocity Poisson’s ratio P-wave packet

Secondary relaxation and dynamic heterogeneity in metallic glasses：A brief review

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Chinese Physics B 2017年第1期26卷 32-41页

作者： j C Qiao[[ Q Wang D crespo Y Yang j M Pelletier School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi＇an 710072 China Centre for Advanced Structural Materials Department of Mechanical and Biomedical Engineering City University of Hong Kong Kowloon Tong Kowloon Hong Kong China Universite de Lyon MATEIS UMR CNRS5510 Bat. B. Pascal INSA-Lyon F-69621 Villeurhanne cedex France Key Laboratory for Structures Institute of Materials Science Shanghai University Shanghai 200444 China Departament de Fisica EETAC Universitat Politecnica de Catalunya 08860-Castelldfels Barcelona Spain

Understanding mechanical relaxation, such as primary（α） and secondary（β） relaxation, is key to unravel the intertwined relation between the atomic dynamics and non-equilibrium thermodynamics in metallic glasses. At a fundamental level, relaxation, plastic deformation, glass transition, and crystallization of metallic glasses are intimately linked to each other, which can be related to atomic packing, inter-atomic diffusion, and cooperative atom movement. Conceptually, βrelaxation is usually associated with structural heterogeneities intrinsic to metallic glasses. However, the details of such structural heterogeneities, being masked by the meta-stable disordered long-range structure, are yet to be understood. In this paper, we briefly review the recent experimental and simulation results that were attempted to elucidate structural heterogeneities in metallic glasses within the framework of β relaxation. In particular, we will discuss the correlation amongβ relaxation, structural heterogeneity, and mechanical properties of metallic glasses.

关键词： metallic glass structural heterogeneity mechanical property secondary relaxation

Comprehensive insights into the thermal and mechanical effects of metallic glasses via creep

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journal of Materials Science & Technology 2022年第4期99卷 39-47页

作者： Z.R.Xu j.C.Qiao j.Wang E.Pineda D.crespo School of Mechanics Civil Engineering and ArchitectureNorthwestern PolytechnicalUniversityXi’an 710072China State Key Laboratory of Solidification Processing Northwestern PolytechnicalUniversityXi’an 710072China Department of Physics Barcelona Research Center in Multiscale Science and TechnologyInstitute of Energy TechnologiesUniversitat Politècnica de CatalunyaBarcelona 08019Spain

Evolution of deformation and relaxation behaviors of a prototypical Cu_(46)Zr_(46)A_(l8)metallic glass was explored by extensive creep tests under both physical aging and cyclic *** insights into the microstructure-induced dynamic heterogeneity which accommodates creep deformation were successively revealed via experimental measurements and spectral *** annihilation of local defects within metallic glass with increasing annealing time and cyclic numbers was observed through the reduction of amplitude in both activation energy spectra and relaxation-time spectra,which were also accompanied by an ascending value of β_(KWW).It is further found that the corresponding deformation units within the metallic glass do not disappear permanently,but are recoverable over the course of cyclic *** apparent suppressed relaxation process can be gradually alleviated with increasing resuming time between two consecutive cycles,behaving differently from physical aging,which indicates a notable discrepancy between thermal treatment and mechanical treatment.

关键词： Metallic glasses Creep Physical aging Cyclic loading Relaxation-time spectrum

The role of copper in enhancing the performance of heteronuclear diatomic catalysts for the electrochemical CO_(2)conversion to C_(1) chemicals

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journal of Energy Chemistry 2023年第10期85卷 490-500,I0013页

作者： Qi Zhao Rachel crespo-Otero Devis Di Tommaso Department of Chemistry School of Physical and Chemical SciencesQueen Mary University of LondonLondon E14NSUK Department of Chemistry University College LondonLondon WC1H 0AJUK

Diatomic catalysts(DACs)with two adjacent metal atoms supported on graphene can offer diverse functionalities,overcoming the inherent limitations of single atom catalysts(SACs).In this study,density functional theory calculations were conducted to investigate the reactivity of the carbon dioxide(CO_(2))reduction reaction(CO_(2)RR)on metal sites of both DACs and SACs,as well as their synergistic effects on activity and *** of the Gibbs free energies of CO_(2)RR and associated values of the limiting potentials to generate C_(1) products showed that Cu acts as a promoter rather than an active catalytic centre in the catalytic CO_(2)conversion on heteronuclear DACs(CuN_(4)-MN_(4)),improving the catalytic activity on the other metal compared to the related SAC MN_(4).Cu enhances the initial reduction of CO_(2)by promoting orbital hybridization between the key intermediate*COOH 2p-orbitals and the metals 3d-orbitals around the Fermi *** degree of hybridization in the DACs CuN_(4)-MN_(4) decreases from Fe to Co,Ni,and *** work demonstrates how Cu regulates the CO_(2)RR performance of heteronuclear DACs,offering an effective approach to designing practical,stable,and high-performing diatomic catalysts for CO_(2)electroreduction.

关键词： Electrocatalytic CO_(2)reduction Single atom catalysts Diatomic catalysts Graphene Density functional theory calculations

Software Project Effort Estimation Based on Multiple Parametric Models Generated Through Data Clustering

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journal of Computer Science & Technology 2007年第3期22卷 371-378页

作者： juan j.Cuadrado Gallego Daniel Rodríguez Miguel Angel Sicilia Miguel Garre Rubio Angel García crespo Department of Computer Science The University of Alcalá AlcaláSpain Department of Computer Science Carlos Ⅲ University.Madrid Spain

Parametric software effort estimation models usually consists of only a single mathematical relationship. With the advent of software repositories containing data from heterogeneous projects, these types of models suffer from poor adjustment and predictive accuracy. One possible way to alleviate this problem is the use of a set of mathematical equations obtained through dividing of the historical project datasets according to different parameters into subdatasets called partitions. In turn, partitions are divided into clusters that serve as a tool for more accurate models. In this paper, we describe the process, tool and results of such approach through a case study using a publicly available repository, ISBSG. Results suggest the adequacy of the technique as an extension of existing single-expression models without making the estimation process much more complex that uses a single estimation model. A tool to support the process is also presented. Keywords software engineering, software measurement, effort estimation, clustering

关键词： software engineering software measurement effort estimation clustering

Analysis of the hydrological safety of dams combining two numerical tools:Iber and DualSPHysics

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journal of Hydrodynamics 2018年第1期30卷 87-94页

作者： j.González-Cao O.García-Feal j.M.Domínguez A.j.C.crespo M.Gómez-Gesteira Environmental Physics Laboratory (EPHYSLAB) Universidade de Vigo Campus AsLagoas

The upgrade of the hydrological safety of dams is a critical issue to avoid failures that can dramatically affect people and assets. This paper shows a numerical methodology to analyse the safety of the Belesar dam（NW, Spain） based on two different numerical codes. First, a mesh-based code named Iber, suited to deal with large 2-D domains, is used to simulate the impoundment. The initial conditions and the inlet provided to Iber correspond to the maximum water elevation and the maximum expected inflow to the impoundment defined in the technical specifications of the dam, which are associated to the more hazardous operation conditions of the dam. Iber provides information about the time needed for water to attain the crest of the dam when floodgates are closed. In addition, it also provides the velocity of discharge when gates are opened. Then, a mesh-free code named DualSPHysics, which is especially suited to deal with complex and violent 3-D flows, is used to reproduce the behaviour of one of the spillways of the dam starting from the results obtained with Iber, which are used as inlet conditions for DualSPHysics. The combined results of both model show that the left spillway can discharge the surplus of water associated to the maximum inflow to the reservoir if the gates of the spillways are opened before the overtopping of the dam was observed. In addition, water depth measured on the spillway is considerably lower than the lateral walls, preventing overtopping. Finally, velocities at different points of the spillway showed to be in good agreement with theoretical values.

关键词： Hydrological safety dam numerical simulation Iber DualSPHysics

Carbon isotopes of graphite:Implications on fluid history

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Geoscience Frontiers 2012年第2期3卷 197-207页

作者： F.j.Luque E.crespo-Feo j.F.Barrenechea L.Ortega Departamento de Cristalografía y Mineralogía Facultad de Geología Universidad Complutense de Madrid 28040 MadridSpain Instituto de Geociencias(UCM-CSIC) Jos Antonio Novais 228040 MadridSpain Departamento de Cristalografia y Mineralogia Facultad de Geología Universidad Complutense de Madrid28040 MadridSpain Departamento de Cristalografía y Mineralogía Facultad de Geología Universidad Complutense de Madrid28040 MadridSpain

Stable carbon isotope geochemistry provides important information for the recognition of funda- mental isotope exchange processes related to the movement of carbon in the lithosphere and permits the elab- oration of models for the global carbon cycle. Carbon isotope ratios in fluid-deposited graphite are powerful tools for unravelling the ultimate origin of carbon （organic matter, mantle, or carbonates） and help to constrain the fluid history and the mechanisms involved in graphite deposition. Graphite precipitation in fluid-deposited occurrences results from C02- and/or CH4-bearing aqueous fluids. Fluid flow can be considered as both a closed （without replenishment of the fluid） or an open system （with renewal of the fluid by successive fluid batches）. In closed systems, carbon isotope systematics in graphite is mainly governed by Rayleigh precipi- tation and/or by changes in temperature affecting the fractionation factor between fluid and graphite. Such processes result in zoned graphite crystals or in successive graphite generations showing, in both cases, isotopic variation towards progressive 13C or 12C enrichment （depending upon the dominant carbon phase in the fluid, C02 or CH4, respectively）. In open systems, in which carbon is episodically introduced along the fracture systems, the carbon systematics is more complex and individual graphite crystals may display oscillatory zoning because of Rayleigh precipitation or heterogeneous variations of 613C values when mixing of fluids or changes in the composition of the fluids are the mechanisms responsible for graphite precipitation.

关键词： Graphite Carbon isotopes Crust C-O-H fluids

Thermo-electro-mechanical microstructural interdependences in conductive thermoplastics

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npj Computational Materials 2023年第1期9卷 955-965页

作者： javier crespo-Miguel Sergio Lucarini Angel Arias Daniel Garcia-Gonzalez Department of Continuum Mechanics and Structural Analysis Universidad Carlos III de MadridAvda.de la Universidad 3028911 LeganésMadridSpain Department of Civil and Environmental Engineering Imperial College of LondonSouth Kensington CampusLondon SW72AZUK

Additive manufacturing has enabled the design of thermoplastic components that provide structural support,electrical conductivity and heat generation modulated by mechanical *** mechanisms and interplays that govern the material response at the microstructural level remain,however,***,we develop an experimental method to characterise conductive filaments from a combined mechanical,electrical and thermal *** approach is used to unravel exciting material interplays of conductive polylactic *** overcome experimental limitations that prevent a complete microstructural analysis of the problem,we develop a full-field homogenisation framework and implement it for finite *** framework accounts for viscoplasticity,electrical and thermal conduction,convection and heat generation via joule effect,as well as for the interdependences between *** experimental validation,the framework is applied to virtually optimise fabrication requirements to obtain desired properties in final products,i.e.,stiffer products,filaments with higher conductivities or with better sensing capabilities.

关键词： conductive electrical overcome

Analysis of the anelastic deformation of high-entropy Pd_(20)Pt_(20)Cu_(20)Ni_(20)P_(20) metallic glass under stress relaxation and recovery

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journal of Materials Science & Technology 2022年第12期107卷 82-91页

作者： Y.j.Duan L.T.Zhang T.Wada H.Kato E.Pineda D.crespo j.M.Pelletier j.C.Qiao School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710072China Department of Physics Institute of Energy TechnologiesUniversitat Politècnica de CatalunyaBarcelona 08019Spain Institute for Materials Research Tohoku UniversitySendai 980-8577Japan Universitéde Lyon MATEISUMR CNRS5510Bat.B.PascalINSA-LyonF-69621 Villeurbanne CedexFrance

The anelastic deformation behavior of Pd_(20)Pt_(20)Cu_(20)Ni_(20)P_(20) high-entropy metallic glass was probed by monitoring the stress relaxation and recovery processes. The stress relaxation under consecutive strain steps can be described by the Kohlrausch-Williams-Watts(KWW) function. In addition, considering a hierarchy of relaxation processes related to the structural heterogeneity, a constitutive model is proposed in order to describe the whole process of stress relaxation and determine the contribution of different time scales. Moreover, a crossover from stochastic activation to percolation of flow defects with the ultimate strain can be observed during stress relaxation process. The anelastic recovery process after a strain step is studied as a function of the initial strain level and characterized by means of a direct spectrum analysis. The peaks in the recovery time-spectra revealed the evolution of flow defects in Pd_(20)Pt_(20)Cu_(20)Ni_(20)P_(20) high-entropy metallic glass. The understanding of the atomic free-volume zones effect and the anelastic deformation provides important insight into how atomic structural features affect the deformation behavior of high-entropy metallic glasses, and may provide a new avenue into the improvement of their mechanical properties.

关键词： High-entropy metallic glass Stress relaxation Anelastic deformation Flow defects Free-volume zones