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Retrieval of Elastic Green’s Tensor near a Cylindrical Inhomogeneity from Vector Correlations

Communications in Computational Physics 2008年第1期3卷 250-270页

作者： juan ap´erez-ruiz Francisco Luzon Francisco J.Sanchez-Sesma Grupo de Geof´ısica aplicada Departamento de F´ısica AplicadaUniversidad de Almer´ıaCa˜nada de San Urbano s/n04120-Almer´ıaSpain Departamento de Sismolog´ıa Instituto de IngenieriaUniversidad Nacional Aut´onoma de M´exicoCd.UniversitariaCircuito Escolar s/nCoyoac´an 04510M´exico D.F.Mexico.

Multiple scattering of elastic waves in realistic media makes that averagefield intensities or energy densities follow diffusive processes. In such regime the successiveP to S energy conversions by distributed random inhomogeneities give rise toequipartition which means that in the phase space the available elastic energy is distributedin averagewith equal amounts among the possible states of P and S waves. Insuch diffusive regime the P to S energy ratio equilibrates in an universal way independentof the particular details of the scattering. It has been demonstrated that averagingthe cross correlations at any two points of an elastic medium subjected to diffuse elasticwavefields leads to the emergence of the Green function, which is the wave fieldthat would be observed at one position if an impulsive load is applied at the other. Inthis work we study the problem of the retrieval of the 2D tensor elastodynamic Greenfunction in an infinite elastic space containing a circular cylinder inclusion. We illuminateisotropically the elastic spacewith plane waves. We assume the spectra for both Pand S waves uniform but such that the energy ratio ES/EP=(a/b)2, which is the onepredicted by equipartition theory in two-dimensions. We then show that the Fouriertransform of azimuthal average of the cross-correlation of motion between two pointswithin an elastic medium is proportional to the imaginary part of the exact Green tensorfunction between these points. The numerical results presented here point out thepossibility of detection and imaging of diffractors and resonant diffractors by crosscorrelation even in presence of attenuation exists.

关键词： Multiple scattering elastic waves elastic Green’s tensor

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The effect of ethanol fuel dilution on oil performance and MoDTC tribofilms formation and composition

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Friction 2024年第9期12卷 2108-2125页

作者： juan ruiz-ACERO Felipe KESSLER Henara COSTA Tiago COUSSEAU Polytechnic School Universidade de São PauloSão Paulo 05508-030Brazil School of Food and Chemistry Universidade Federal do Rio GrandeRio Grande 96203-000Brazil School of Engineering Universidade Federal do Rio GrandeRio Grande 96203-900Brazil Mechanical Engineering Department Univ.Tecnológica Federal do ParanáCuritiba 81280-340Brazil University of Newcastle CallaghanSW 2308Australia

Ethanol has emerged as a promising alternative to fossil fuels,but its use can lead to significant dilution in lubricants,particularly during cold start or heavy *** dilution can affect the performance of additives,including friction modifiers like molybdenum dithiocarbamate(MoDTC),which are designed to reduce friction under extreme contact *** research suggests that ethanol may impact the performance of MoDTC,prompting this study’s goal to investigate the effects of ethanol on MoDTC tribofilms and their friction response under boundary lubrication ***,reciprocating tribological tests were performed with fully formulated lubricants containing MoDTC with varying ethanol *** results indicate that a critical ethanol dilution level inhibits friction reduction by MoDTC activation,resulting in friction coefficients(COFs)similar to the base *** tested with simple mixtures of polyalphaolefin(PAO)+MoDTC showed increased COFs with added *** of tested surfaces using Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),and X-ray absorption spectroscopy near the edge structure(XANES)revealed the presence of sulfates,MoO_(3),MoS_(2),and MoS_(x)O_(y)compounds in the tribofilms formed on the surfaces,with and without ethanol diluted in the ***,the addition of ethanol increased the sulfates and MoO_(3)content of the tribofilms at the expense of friction-reducing compounds such as MoS_(2)and MoS_(x)O_(y).These findings suggest that ethanol dilution in lubricants containing MoDTC creates an oxygen-rich interfacial medium that favors the formation of compounds with insufficient friction-reducing capabilities.

关键词： molybdenum dithiocarbamate(MoDTC) ethanol tribofilm friction modifier additive lubricant

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A Stable FE-FD Method for Anisotropic Parabolic PDEs with Moving Interfaces

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Communications on applied Mathematics and Computation 2024年第2期6卷 992-1012页

作者： Baiying Dong Zhilin Li juan ruiz-Alvarez School of Civil and Hydraulic Engineering NingXia UniversityYinchuan 750021NingxiaChina School of Mathematics and Computer Science NingXia Normal UniversityGuyuan 756000NingxiaChina Department of Mathematics North Carolina State UniversityRaleighNC 27695-8205USA Departamento de Matematica aplicada y Estadistica Universidad Politecnica de CartagenaCartagenaSpain

In this paper,a new finite element and finite difference(FE-FD)method has been developed for anisotropic parabolic interface problems with a known moving interface using Cartesian *** the spatial discretization,the standard P,FE discretization is applied so that the part of the coefficient matrix is symmetric positive definite,while near the interface,the maximum principle preserving immersed interface discretization is *** the time discretization,a modified Crank-Nicolson discretization is employed so that the hybrid FE-FD is stable and second order *** terms are needed when the interface crosses grid *** moving interface is represented by the zero level set of a Lipschitz continuous *** experiments presented in this paper confirm second orderconvergence.

关键词： Anisotropic parabolic interface problem Hybrid finite element and finite difference(FE-FD)discretization Modified Crank Nicolson scheme

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Quality assessment of the Topo-Iberia CGPS stations and data quality's effects on postfit ionosphere-free phase residuals

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Geodesy and Geodynamics 2024年第2期15卷 189-199页

作者： juan A.García-Armenteros Center for Advanced Studies in Earth Sciences Energy and Environment(CEACTEMA)University of Jaén23071 JaenSpain

This paper analyzed GPS data from the Topo-Iberia network spanning almost 12 years(2008-2020).The data quality information for all 26 Topo-Iberia stations is provided for the first time,complementing the Spanish Geological Survey’s storage *** analyses based on quality indicators obtained using TEQC have been carried *** guidelines and data quality information from the IGS stations have been considered as the quality references,with the stations ALJI,EPCU,and TIOU standing out as the worst stations,while on the contrary,FUEN,PALM,PILA,and TRIA meet the quality requirements to become an IGS *** relationship between the GPS data quality and their GAMIT-and Gipsy X-derived postfit ionosphere-free phase residuals has also been investigated,and the results reveal an inversely proportional *** has been found that the stations showing an increase in elevation of the horizon line,also show an increase in cycle slips and multipath,are among the poorest quality stations,and among those with the highest postfit RMS of phase ***,the evolution of the vegetation around the antenna should be considered as it could cause a progressive loss of quality,which is not complying with the IGS *** quality assessment shows that the Topo-Iberia stations are appropriate for geodetic purposes,but permanent monitoring would be necessary to avoid the least possible loss of data and *** addition,a method to characterize the GNSS data quality is proposed.

关键词： GPS dataquality's effects IGS quality standard Postfit LC phase residual Qualityassessment Topo-Iberia CGPS network

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Thermodynamic property of sandwich cylindrical shell structure with metallic wire mesh:Numerical modeling and experimental analysis

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Chinese Journal of Aeronautics 2024年第1期37卷 138-152页

作者： Xin XUE Guojian SHEN juan LIAO Institute of Metal Rubber&Vibration Noise School of Mechanical Engineering and AutomationFuzhou UniversityFuzhou 350116China Fujian Shuikou Power Generation Group Co. LTDFuzhou 350000China

As a new addition to lightweight composite structures,the sandwich cylindrical shell with a metallic wire mesh core has emerged as a promising solution for thermodynamic performance analysis at elevated *** intricate interwoven cellular formations within the metallic wire mesh pose difficulties for thermo-mechanical modeling and property ***,the constitutive models employed to characterize hysteresis phenomena were presented,comprising isotropic elasticity,Bergstrom-Boyce model,Ogden hyper-elasticity,and parameter identification through mechanical examinations at varying ***,the finite element modeling of cylindrical shell structures was determined for modal and steady-state dynamic ***,the experimental procedures were carried out,including the preparation of the sandwich cylindrical shell and the dynamic testing *** first-order natural frequency of the cylindrical shell structure is close to the resonance frequency of the dynamic test results,with a maximum error of 6.5%,demonstrating the accuracy of the simulation *** compared to the solid-core cylindrical shell,the average insertion loss of the sandwich cylindrical shell structure within the frequency range of 10–1000 Hz at room temperature is up to 11.09 ***,at elevated temperatures,the average insertion loss of the sandwich cylindrical shell decreases but fluctuates as the temperature changes.

关键词： Energy dissipation Metallic matrix composites Numerical analysis Sandwich structure Thermodynamic properties

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Interface property of dissimilar Ti-6Al-4V/AA1050 composite laminate made by non-equal channel lateral co-extrusion and heat treatment

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Defence Technology（防务技术） 2024年第3期33卷 197-208页

作者： juan Liao Mengmeng Tian Xin Xue School of Mechanical Engineering and Automation Fuzhou UniversityFuzhou 350116China

The purpose of this paper is to examine the effect of processing parameters and subsequent heat treatments on the microstructures and bonding strengths of Ti-6Al-4V/AA1050 laminations formed via a non-equal channel lateral co-extrusion *** microstructural evolution and growth mechanism in the diffusion layer were discussed further to optimize the bonding quality by appropriately adjusting process *** electron microscopes(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD)were used to characterize interfacial diffusion *** shear test was used to determine the mechanical properties of the interfacial diffusion *** experimental results indicate that it is possible to co-extrusion Ti-6Al-4V/AA1050 compound profiles using non-equal channel lateral *** heat treatment processes affect the thickness of the diffusion *** the temperature and time of heat treatment increase,the thickness of the reaction layers increases ***,the shear strength of the Ti-6Al-4V/AA1050 composite interface is proportional to the diffusion layer *** is observed that a medium interface thickness results in superior mechanical performance when compared to neither a greater nor a lesser interface *** characterization of all heat treatments reveals that the only intermetallic compound observed in the diffusion layers is TiAl_(3).Due to the inter-diffusion of Ti and Al atoms,the TiAl_(3) layer grows primarily at AA1050/TiAl_(3) interfaces.

关键词： Shear strength Co-extrusion Heat treatment Microstructure Intermetallic compounds

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Single-neuron neurodegeneration as a degenerative model for Parkinson’s disease

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Neural Regeneration Research 2024年第3期19卷 529-535页

作者： Sandro Huenchuguala juan Segura-Aguilar Escuela de Tecnología Médica Facultad de SaludUniversidad Santo TomásLos CarrerasOsornoChile Molecular&Clinical Pharmacology Instituto de Ciencias Biomedicas(ICBM)Faculty of medicineUniversity of ChileIndependenciaSantiagoChile

The positive effect of levodopa in the treatment of Parkinson’s disease,although it is limited in time and has severe side effects,has encouraged the scientific community to look for new drugs that can stop the neurodegenerative process or even regenerate the neuromelanin-containing dopaminergic nigrostriatal *** preclinical studies with coenzyme Q10,mitoquinone,isradipine,nilotinib,TCH346,neurturin,zonisamide,deferiprone,prasinezumab,and cinpanemab prompted clinical ***,these failed and after more than 50 years levodopa continues to be the key drug in the treatment of the disease,despite its severe side effects after 4–6 years of chronic *** lack of translated successful results obtained in preclinical investigations based on the use of neurotoxins that do not exist in the human body as new drugs for Parkinson’s disease treatment is a big *** our opinion,the cause of these failures lies in the experimental animal models involving neurotoxins that do not exist in the human body,such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and 6-hydroxydopamine,that induce a very fast,massive and expansive neurodegenerative process,which contrasts with the extremely slow one of neuromelanin-containing dopaminergic *** exceedingly slow progress of the neurodegenerative process of the nigrostriatal neurons in idiopathic Parkinson’s patients is due to(i)a degenerative model in which the neurotoxic effect of an endogenous neurotoxin affects a single neuron,(ii)a neurotoxic event that is not expansive and(iii)the fact that the neurotoxin that triggers the neurodegenerative process is produced inside the neuromelanin-containing dopaminergic *** endogenous neurotoxin that fits this degenerative model involving one single neuron at a time is aminochrome,since it(i)is generated within neuromelanin-containing dopaminergic neurons,(ii)does not cause an expansive neurotoxic effect and(iii)triggers all the mechanisms involved in t

关键词： 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine 6-hydroxydopamine aminochrome dopaminergic neurons DT-diaphorase exogenous neurotoxins glutathione transferase M2-2

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Understanding the Link:Emotional Attention in Italian Families and Children’s Social Development

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International Journal of Mental Health Promotion 2024年第9期26卷 709-718页

作者： Catalda Corvasce juan Pedro Martínez-Ramón Francisco Manuel Morales-Rodríguez Lidia Pellicer-García Inmaculada Méndez Cecilia ruiz-Esteban Liceo Statale“Carlo Cafiero” Barletta(BT)76121Italy Department of Developmental Psychology and Education University of MurciaMurcia30100Spain Department of Developmental Psychology and Education University of GranadaCampus of La CartujaGranadaCP 18071Spain Department of Spanish Language and General Linguistics University of MurciaCampus of La MercedMurciaCP 30001Spain

Background:Emotional attention refers to the capacity to recognize and properly respond to one’s and others’emotional *** another note,family is a primary source of socialization that influences the development of various social *** another line,adolescence is a complex stage that has been associated with emotional difficulties that could be related to competences such as prosociability and *** is inferred that through the family context and the attention that is processed,a series of competencies are transmitted to the youngsters,but this relationship is still *** this reason,the study’s purpose was to examine the relationship between the emotional attention of mothers and fathers and the social and prosocial competencies of their ***:To accomplish this,a cross-sectional study and ex post facto design were *** Trait-Meta Mood Scale(TMMS-24)-to assess emotional attention-,the Strengths and Difficulties Questionnaire(SDQ)-to determine the prosociality dimension-,and the Test on Passing Developmental Tasks in Adolescence(TCS-A)-to measure social inclusionwere *** participants were N=228 families composed of n=114 mothers/fathers(67.5%females)and n=114 daughters/sons(38.5%females)selected through non-probabilistic sampling using a convenience sample in the Bari region of Italy.A descriptive and inferential analysis-Student’s test and Pearson’s correlation-was performed with the statistic package SPSS version 28(significance level p<0.05).Results:The findings showed that the families possessed an adequate background in emotional attention and that their daughters and sons were also generally well-adjusted in social inclusion and *** also found certain signs that the prosocial competence of the children could be related to the behavior of their mothers and ***:In conclusion,social inclusion is related to prosocial behavior,and maybe primarily cultivated within families where paren

关键词： Educational style coping strategies stress social inclusion emotional attention prosociality

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Presynaptic endoplasmic reticulum architecture and hereditary spastic paraplegia

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Neural Regeneration Research 2024年第3期19卷 485-486页

作者： juan JoséPérez-Moreno Instituto de Biomedicina de Sevilla(IBiS) Hospital Universitario Virgen Del Rocío/CSIC/Universidad de Sevillaand Departamento de Biología CelularFacultad de BiologíaUniversidad de SevillaSevilleSpain

Hereditary spastic paraplegia(HSP)is a clinically and genetically heterogeneous neurodegenerative disorder,characterized primarily by progressive spasticity and weakness in the lower *** ients can also experience peripheral neuropathy,cognitive impairment,and other neurological *** date,more than 80 genes have been implicated in HSP,encompassing various cellular components,although mutations in genes encoding endoplasmic reticulum(ER)-shaping proteins are the most prevalent(Parodi et al.,2017).ER-shaping proteins are generally known for regulating the tubulation and curvation of the ER,but most of them show additional functions,including fusion of ER tubules,microtubule-severing,ER autophagy,lipid droplet synthesis,contact sites with other organelles(Öztürk et al.,2020).This highlights the complexity of studying the role of these proteins and the link between ER function and HSP.

关键词： reticulum endoplasmic

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Attractor for the Extensible Beam Equation with Nonlocal Weak Damping on Time–Dependent Space

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Acta Mathematica Sinica,English Series 2024年第4期40卷 1115-1126页

作者： Chun Xiang ZHAO Feng juan MENG Institute of applied System Analysis Jiangsu UniversityZhenjiang 212013P.R.China School of Mathematics and Physics Jiangsu University of TechnologyChangzhou 213001P.R.China

In this article,we consider the long-time behavior of extensible beams with nonlocal weak damping:ε(t)u_(tt)+Δ^(2)u-m(‖▽u‖^(2))Δu+‖u_(t)‖^(p_(u_(t)))+f(u)=h,whereε(t)is a decreasing function vanishing at *** the theory of process on time-dependent spaces,we investigate the existence of the time-dependent attractor by using the Condition(C_(t))method and more detailed *** results obtained essentially improve and complete some previous works.

关键词： Time-dependent attractor extensible beams equation nonlocal weak damping

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