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A fast numerical method of introducing the strengthening effect of residual stress and strain to tensile behavior of metal matrix.composites

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Journal of Materials Science & technology 2021年第28期87卷 167-175页

作者： J.F.Zhang x.x.Zhang H.andrä Q.Z.Wang B.L.x.ao Z.Y.Ma Shi-changx. Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China University of Chinese Academy of Sciences Beijing 100049China Fraunhofer Institute for Industrial Mathematics Fraunhofer-Platz 1Kaiserslautern 67663Germany

thermal residual stress and strain(tRSS)in particle reinforced metal matrix.composites(PRMMCs)are believed to cause strengthening effects,according to previous ***,the representative volume element(RVE)based computational homogenization technique was used to study the tensile deformation of PRMMCs with different particle aspect ratios(AR).the influence of tRSS was assessed quantitatively via comparing simulations with or without the cooling *** was found that the strengthening effect of tRSS was affected by the particle *** the average strengthening effect of tRSS,a fast method of introducing the strengthening effect of tRSS to the tensile behavior of PRMMCs was *** new method has reduced the computational cost by a factor *** effect of tRSS on continuous fiber-reinforced metal matrix.composite was found to have a softening-effect during the entire tensile deformation process because of the pre-yield effect caused by the cooling process.

关键词： Metal matrix.composites(MMC) Finite element analysis(FEA) Representative volume element(RVE) Residual stress and strain Aspect ratio

touristic urbanization and greening of coastal dune fields:A long-term assessment of a temperate sandy barrier of Argentina

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Journal of Geographical Sciences 2025年第1期 206-230页

作者： GARZO Pedro andrés DADON José Roberto ISLA Federico Ignacio Instituto de Investigaciones Marinas y Costeras (IIMyC-CONICEt/UNMDP) Instituto de Geología de Costas y del Cuaternario Dr.Enrique J.Schnack (IGCC-CIC/UNMDP) Universidad de Buenos Aires Facultad de Arquitectura Dise?o y Urbanismo Centro de Investigaciones Gestión de Espacios Costeros (GEC-FADU/UBA) Consejo Nacional de Investigaciones Científicas y técnicas (CONICEt)

Dune barrier systems represent highly sought-after coastal landscapes for tourism and urban development around the world. However, a century ago, they were considered hazardous environments due to their great dynamic nature. As a result, stabilization practices were considered necessary. the systematic introduction of fast-growing ex.tic trees helped stabilize the sand, making it easier for tourism urbanization to take place, but also leading to erosion processes. this paper aims to assess long-term changes in vegetation cover over a large temperate barrier in Argentina. this complex.region includes urban resorts, afforestation zones, and protected areas. A GIS-based geospatial analysis was conducted using a large satellite database(> 350 images), and the future evolution of the vegetation was modeled. the results revealed two primary spatiotemporal patterns associated with a gradual ex.ansion of vegetation cover, accompanied by a concurrent reduction in sandy areas. In 1986, the dune area comprised 75% more surface than vegetation, whereas in 2021, it represented 60% less than vegetation. Furthermore, the 2050 scenario suggests a potential 40% reduction of dunes in certain areas. It is necessary to enhance management actions aimed at maintaining dune mobility and ensuring local and regional sediment balance. Long-term management strategies must focus on restoring native plant communities and controlling invasive species, and avoiding new dune fix.tion initiatives based on the introduction of ex.tic species.

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terahertz Radiation from a Longitudinal Electric Field Biased Femtosecond Filament in Air

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Chinese Physics Letters 2020年第6期37卷 44-47页

作者： Yi Lin Shaojie Liu Aurélien Houard andréMysyrowicz Vladimir t.tikhonchuk Shanghai Key Lab of Modern Optical System University of Shanghai for Science and TechnologyShanghai 200093China Laboratoire d’Optique Appliquée ENSTA ParisEcole PolytechniqueCNRSInstitut Polytechnique de Paris828 Boulevard des Maréchaux91762 Palaiseau cedexFrance Centre Lasers Intenses et Applications University of Bordeaux-CNRS-CEA351 Cours de la Liberation33405 Talence cedexFrance ELI-Beamlines Institute of PhysicsCzech Academy of Sciences25241 Dolni BrezanyCzech Republic

the terahertz(tHz)temporal waveform and spectrum from a longitudinal electrically biased femtosecond filament is studied *** initial direction of the electron motion inside the unbiased filament plasma is deduced from the transformation of the tHz temporal waveform with applied fields of opposite ***,a spectrum shift to lower frequency of the tHz spectrum is observed in the presence of a biased *** agrees well with theoretical predictions.

关键词： field. spectrum opposite

Microscopic stresses in carbon nanotube reinforced aluminum matrix.composites determined by in-situ neutron diffraction

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Journal of Materials Science & technology 2020年第19期54卷 58-68页

作者： x.x.Zhang J.F.Zhang Z.Y.Liu W.M.Gan M.Hofmann H.andrä B.L.x.ao Z.Y.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China German Engineering Materials Science Centre at MLZ Helmholtz-Zentrum GeesthachtD-85747 GarchingGermany Heinz Maier-Leibnitz Zentrum(MLZ) Technische Universität MünchenD-85747 GarchingGermany Fraunhofer Institute for Industrial Mathematics Fraunhofer-Platz 1Kaiserslautern 67663Germany

One of the most desired strengthening mechanisms in the carbon nanotube reinforced aluminum matrix.composites(CNt/Al)composites is the load transfer strengthening mechanism(LtSM).However,a fundamental issue concerning the LtSM is that quantitative measurements of load partitioning in these composites during loading are very *** this study,in-situ neutron diffraction study on the tensile deformation of the 3 vol.%CNt/2009 Al composite and the unreinforced 2009 Al alloy was ***{311}and{220}diffraction elastic constants(DECs)of the 2009 Al alloy were *** those DECs the average stress in the 2009 Al matrix.of the composite was *** the average stress in the CNts was separated by using the stress equilibrium *** homogenization models were also applied to ex.lain the stress evolution in each *** results agree with ex.erimental *** the present case,the average stress in the CNts reaches 1630 MPa at the yield strength of the composite based on linear regression of the measured data,which leads to an increment of yield strength by about 37 *** the result of this work,an approach to quantify load partitioning in the CNts is developed for the CNt/Al composites,which can be applied to optimize the mechanical properties of the composites.

关键词： Carbon nanotubes Aluminum matrix.composites In-situ neutron diffraction Load partitioning

Litterfall production modeling based on climatic variables and nutrient return from stands of Eucalyptus grandis Hill ex.Maiden and Pinus taeda L.

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Journal of Forestry Research 2024年第5期35卷 26-36页

作者： andrés Baietto andrés Hirigoyen Jorge Hernández Amabelia del Pino Forest Department Faculty of AgronomyUniversity of the Republic12900 MontevideoUruguay National Research Program of Forest Production National Agriculture Research InstituteINIA97000 TacuarembóUruguay Soil and Water Department Faculty of AgronomyUniversity of the Republic12900 MontevideoUruguay

Native grasslands in the Pampas of South America are increasingly being replaced by Eucalyptus and Pinus *** short rotation regimes used for the stands require high nutrient levels,with litterfall being a major source of nutrient *** model the litterfall production using climatic variables and assess the nutrient return in 14-year-old Eucalyptus grandis and Pinus taeda stands,we measured litter production over 2 years,using conical litter traps,and monitored climatic *** temperature,accumulated precipitation,and mean max.mum vapor pres-sure deficit at the seasonal level influenced litterfall produc-tion by ***;seasonal accumulated precipitation and mean max.mum temperature affected litterfall by *** regression tree modeling based on these climatic vari-ables had great accuracy and predictive power for ***(N=33;MAE(mean absolute error)=0.65;RMSE(root mean square error)=0.91;R^(2)=0.71)and ***(N=108;MAE=1.50;RMSE=1.59;R^(2)=0.72).the nutrient return followed a similar pattern to litterfall deposition,as well as the order of importance of macronutrients(***:Ca>N>K>Mg>P;***:N>Ca>K>Mg>P)and micronutrients(*** and ***:Mn>Fe>Zn>Cu)in both *** study constitutes a first approx.mation of factors that affect litterfall and nutrient return in these systems.

关键词： Afforestation Litterfall Nutrient recycling Climate modeling Myrtaceae Pinaceae

Surface movement above old coal longwalls after mine closure

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International Journal of Mining Science and technology 2017年第3期27卷 481-490页

作者： andré Vervoort Pierre-Yves Declercq Department of Civil Engineering KU Leuven Leuven 3001 Belgium Geological Survey of Belgium Royal Belgian Institute of Natural Sciences Brussels 1000 Belgium

Although most subsidence occurs in the months and years after mining by the longwall method, surface movement is still occurring many decades after the mining. the aim of the study is to quantify the long term behavior. Satellite data(radar-interferometry) were analyzed to study an area of about 2 km^2 during the 18 years following the closure of the underground infrastructure and the flooding of the underground workings and rock mass. It was observed that, on average, a residual downward movement took place till 7–12 years after the closure, followed by a clear uplift. However, the first signs of an uplift occurred in certain sub-areas 3–4 years after the closure. Zones within the area studied were identified with either larger or smaller movements. However, the spatial variation of the surface subsidence or uplift could not be directly ex.lained by the characteristics of mining.

关键词： Coal mining Surface movement Subsidence Uplift Radar-interferometry

Ex.erimental approaches to select tree species for forest restoration:effects of light,water availability and interspecific competition in degraded areas

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Journal of Forestry Research 2022年第4期33卷 1197-1207页

作者： Johanna Croce Ernesto I.Badano Carolina B.trigo Fernanda Martinez-Galvez andrés tálamo Laboratorio de Ecología Aplicada a la Conservación Instituto de Bio y Geociencias del Noroeste ArgentinoConsejo de Investigaciones Científi cas y Técnicas-Universidad Nacional de SaltaAvenida Bolivia 51504400 SaltaArgentina IPICYt/División de Ciencias Ambientales Instituto Potosino de Investigación Científi ca y TecnológicaCamino a la Presa San José2055Colonia Lomas 4^(a)Sección78216 San Luis PotosíMéxico

Knowing what native trees can recr uit on degraded areas allows selecting the best species to restore these ***,as this information is not often available,ex.erimentation is required before large-scale *** study used ex.situ ex.eriments to make these decisions on *** with r-strategist plants,ex.essive solar radiation and water shortage commonly impair tree recruitment in open *** ex.eriments focused on the interactions among these factors and were conducted with three pioneer species from seasonally dry forests of northwest Argentina,Anadenanthera colubrina,Ceiba chodatii and Jacaranda *** of each species were sown at two light levels(sunlight/shade),two rainfall levels(full/reduced)and two levels of interspecific competition(with/without competitor)in a tree *** emergence and survival were monitored over a year and the results indicate that species differentially respond to varying levels of light and *** of *** tolerated water shortages under elevated solar radiation,which are desirable features for forest *** of *** tolerated shade and drought,suggesting that they require shading for establishing in open ***,*** seedlings neither tolerated full sunlight nor water shortages,suggesting that this species requires shading and regular watering if used in *** of the effects of light and water,the survival of all species was reduced by interspecific *** results highlight the importance of ex.erimentation for selecting the best species for forest restoration and can enhance the cost/benefit ratios of these actions.

关键词： Common-garden ex.eriments Drought Ecological restoration Interspecific competition Seedling survival Shade

Upward surface movement above deep coal mines after closure and flooding of underground workings

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International Journal of Mining Science and technology 2018年第1期28卷 53-59页

作者： andré Vervoort Pierre-Yves Declercq Department of Civil Engineering KU Leuven Geological Survey of Belgium Royal Belgian Institute of Natural Sciences

After the mass closures of entire coal mine districts in Europe at the end of the last century, a new phenomenon of surface movement was observed—an upward *** most surface movement(i.e., subsidence) occurs in the months and years after mining by the longwall method, surface movement still occurs many decades after mining is *** the closure and flooding of underground ex.avations and surrounding rock, this movement was *** paper focuses on quantifying the upward movement in two neighboring coal mines(Winterslag and Zwartberg, Belgium).the study is based on data from a remote sensing technique: interferometry with synthetic aperture radar(INSAR).the results of the study show that the rate of upward movement in the decade after closure is about 10 mm/year on *** upward movements are not linked directly to the past ex.loitation directly underneath a *** amounts of subsidence at specific locations are linked mainly to their positions relative to an inverse trough shape situated over the entire mined-out areas and their immediate *** features, such as geological faults, can have a secondary effect on the local variation of the *** processes of subsidence and uplift are based on completely different *** is initiated by a caving process, while the process of uplift is clearly linked to flooding.

关键词： Coal mining Surface movement Subsidence Uplift Radar-interferometry

Atacama Field Campaign: laboratory and in-situ measurements for remote sensing applications

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International Journal of Digital Earth 2019年第1期12卷 43-61页

作者： Cristian Mattar andrés Santamaría-Artigas Flavio Ponzoni Cibele t.Pinto Carolina Barrientos Glynn Hulley Laboratory for Analysis of the Biosphere(LAB) University of ChileSantiagoChile Department of Geographical Sciences University of MarylandCollege ParkMDUSA Divisão de Sensoriamento Remoto(DSR) Instituto Nacional de Pesquisas Espaciais(INPE)São PauloBrasil Aerial Photogrammetric Service(SAF) Chilean Air ForceSantiagoChile Jet Propulsion Laboratory(JPL) California Institute of TechnologyPasadenaCAUSA

this work presents the preliminary results of the first field calibration campaign performed in the Atacama Desert,Chile,between the 18 and 22 August 2014,called the Atacama Field Campaign(AtAFIC 2014).In situ measurements were performed in order to spectrally characterize the surface reflectance spectra between 0.3 and 2.5μm,radiometric temperature(8.0–14.0μm)and atmospheric measurements.A soil sample was collected and analyzed using fourier transform Infrared Spectroscopy and x.Ray Diffraction techniques to characterize the surface reflectance spectra and mineralogical composition,*** land surface emissivity in addition to GOES,MODIS and Landsat-8 land surface temperature(LSt)were also *** showed that the spectral features of the Atacama soil and the characteristics of this geographical zone,which is featured as the most hyper-arid and cloudless place in the world,make this area a potential target for surface reflectance *** and night LSt comparison between field and remote sensing data are lower than 2 K and the Root Mean Square Error for land surface emissivity is close to 2%.this work opens the possibilities to consider the Atacama Desert as a reference target for calibration and validation activities for earth observation missions’purposes.

关键词： Atacama spectroradiometry emissivity temperature surface reflectance