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Experimental Investigation on Friction Welding of UNs s32205 Duplex stainless steel

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Acta Metallurgica sinica(English Letters) 2014年第6期27卷 995-1007页

作者： P. M. Ajith P. sathiya s. Aravindan Department of Production Engineering National Institute of Technology Department of Mechanical Engineering Indian Institute of Technology Delhi

UNs s 32205 duplex stainless steel specimens were joined by continuous drive friction welding process. The experiments were conducted as per the Taguchi（L16 orthogonal array） method. The friction welding process parameters such as heating pressure, heating time, upsetting pressure, upsetting time, and speed of rotation were fixed with low,medium, and high levels of range based on the machine capacity, and the required knowledge was acquired from the preliminary experiments. The joint characterization studies included micro structural examination and evaluation of mechanical properties of the joints. Microhardness variation, impact toughness, and tensile strength of the joints were evaluated. Neither a crack nor an incomplete bonding zone was observed. The tensile strength of the joints was higher than the strength of the base material, and the friction and upsetting pressures were found to influence the joint strength. The tensile strength of all the welds was observed to be increasing with an increase in the rotational speed. The toughness of the friction welds was evaluated at room temperature and also at subzero（cryo） temperature conditions. The toughness for friction welds was found to be superior to the fusion welds of duplex stainless steel at room temperature and cryo conditions. Weldments exhibited better corrosion resistance than the parent material.

关键词： Duplex stainless steel Hardness Tensile strength Toughness Microstructure Corrosion

Plant cover as an estimator of above-ground biomass in semi-arid woody vegetation in Northeast Patagonia,Argentina

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Journal of Arid Land 2021年第9期13卷 918-933页

作者： Laura B RODRIGUEZ silvia s TORREs ROBLEs Marcelo F ARTURI Juan M ZEBERIO Andrés C H GRAND Néstor I GAsPARRI National University of Río Negro Atlantic HeadquartersCenter for Environmental Studies from Norpatagonia(CEANPa)Viedma 8500Argentina National Council of scientific and Technical Research(CONICET) Viedma 8500Argentina Ecological and Environmental systems Research Laboratory(LIsEA) National University of La PlataLa Plata 1900Argentina National Institute of Agricultural Technology(INTA) AER PatagonesCarmen de Patagones 8504Argentina Institute of Regional Ecology(IER) National University of Tucumán(UNT)-National Council of Scientific and Technical Research(CONICET)Tucumán 4000Argentina Faculty of Natural sciences and Miguel Lillo Institute National University of Tucumán(UNT)Yerba Buena 4107Argentina

The quantification of carbon storage in vegetation biomass is a crucial factor in the estimation and mitigation of CO2 ***,arid and semi-arid regions are considered an important carbon ***,they have received limited attention and,therefore,it should be a priority to develop tools to quantify biomass at the local and regional *** plant variables,such as stem diameter and crown area,were reported to be good predictors of individual plant ***-level variables,such as plant cover and mean height,are also easy-to-measure estimators of above-ground biomass(AGB)in dry *** this study,we estimated the AGB in semi-arid woody vegetation in Northeast Patagonia,*** evaluated whether the AGB at the stand level can be estimated based on plant cover and to what extent the estimation accuracy can be improved by the inclusion of other field-measured structure *** also evaluated whether remote sensing technologies can be used to reliably estimate and map the regional mean *** this purpose,we analyzed the relationships between field-measured woody vegetation structure variables and AGB as well as LANDsAT TM-derived *** obtained a model-based ratio estimate of regional mean AGB and its standard *** plant cover allowed us to obtain a reliable estimation of local AGB,and no better fit was attained by the inclusion of other structure *** stand-level plant cover ranged between 18.7%and 95.2%and AGB between about 2.0 and 70.8 Mg/hm^(2).AGB based on total plant cover was well estimated from LANDsAT TM bands 2 and 3,which facilitated a model-based ratio estimate of the regional mean AGB(approximately 12.0 Mg/hm^(2))and its sampling error(about 30.0%).The mean AGB of woody vegetation can greatly contribute to carbon storage in semi-arid ***,plant cover estimation by remote sensing images could be used to obtain regional estimates and map biomass,as well as to assess and monitor the i

关键词： above-ground biomass shrublands ratio estimation carbon storage remote sensing Patagonia

Fundamental solutions for axi-symmetric translational motionof a microstretch fluid

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Acta Mechanica sinica 2012年第3期28卷 605-611页

作者： H.H.sherief M.s.Faltas E.A.Ashmawy Department of Mathematics Faculty of ScienceAlexandria University

The fundamental solution for the axi-symmetric translational motion of a microstretch fluid due to a concen- trated point body force is obtained. A general formula for the drag force exerted by the fluid on an axi-symmetric rigid par- ticle translating in it is then deduced. As an application to the obtained drag formula, this paper has discussed the problem of creeping translational motion of a rigid sphere in a mi- crostretch fluid. The slip boundary condition on the surface of the spherical particle is applied. The drag force and the other physical quantities are obtained and represented graph- ically for various values of the micropolarity and slip param- eters.

关键词： Drag force Fundamental solution Mi-crostretch fluid slip condition

spectroscopic investigations on Dy^(3+) ions doped zinc lead alumino borate glasses for photonic device applications

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Journal of Rare Earths 2019年第1期37卷 52-59,M0004页

作者： Nisha Deopa shubham saini sumandeep Kaur Aman Prasad A.s.Rao Department of Applied Physics Delhi Technological University

This paper presents the structural, optical absorption, photoluminescence (PL) and decay spectral properties of Dy^(3+)ions doped zinc lead alumino borate (ZPAB) glasses to elucidate their possible usage in photonic devices such as w-LEDs and lasers. A broad hump shown by the XRD spectrum recorded for an un-doped ZPAB glass confirms its non-crystalline nature. The Judd-Ofelt (J-O) intensity parameter evaluated from the measured oscillator strengths of the absorption spectral features were used to estimate various radiative parameters and also to understand the nature of bonding between Dy^(3+)ions and oxygen ligands. Under 350 nm excitation, the as-prepared glasses are exhibiting two emission bands^4F_(9/2)→~6H_(15/2)(blue),and^4F_(9/2)→~6H_(13/2)(yellow) at 483 and 575 nm,respectively. From the PL spectra,the Y/B ratio values, CIE chromaticity color coordinates and color correlated temperature (CCT) were evaluated. The experimental lifetimes measured from the decay profiles are decreasing with increase in Dy^(3+)ions concentration in these glasses which may be attributed to the cross-relaxation and nonradiative multiphonon relaxation process. Decay profiles observed for higher concentration were well fitted to Inokuti-Hirayama (I-H) model to understand the energy transfer process and subsequent decrease in experimental lifetimes. The higher values of radiative parameters, emission cross-sections,quantum efficiency, optical gain and gain band width suggest the suitability of 0.5 mol%of Dy^(3+) ions in these ZPAB glasses for the photonic device application.

关键词： Glasses J-O parameters Luminescence Inokuti-Hirayama model Energy transfer Rare earths

Microstructures and Mechanical Properties of Al/Mg Alloy Multilayered Composites Produced by Accumulative Roll Bonding

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Journal of Materials science & Technology 2011年第1期27卷 15-21页

作者： H.s. Liu B. Zhang G.P. Zhang shenyang National Laboratory for Materials science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Key Laboratory for Anisotropy and Texture of Materials of Ministry of Education School of Materials & Metallurgy Northeastern University Shenyang 110004 China

Al/Mg alloy multilayered composites were produced successfully at the lower temperature（280 C） by accumulative roll bonding（ARB） processing *** microstructures of Al and Mg alloy layers were characterized by scanning electron microscopy and transmission electron *** hardness and three-point bending tests were conducted to investigate mechanical properties of the *** is found that Vickers hardness,bending strength and stiffness modulus of the Al/Mg alloy multilayered composite increase with increasing the ARB *** and crack propagation along the interface are the two main failure modes of the multilayered composite subjected to bending *** and fracture mechanisms of the composite are analyzed.

关键词： Accumulative roll bonding(ARB) Al/Mg alloy multilayered composite Ultra-fine grains Hardness Bending properties

Global changes explain the long-term demographic trend of the Eurasian common lizard (squamata: Lacertidae)

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Current Zoology 2022年第2期68卷 221-228页

作者： Jose L.HORREO Patrick s.FITZE Department of Genetics Physiology and MicrobiologyComplutense University of MadridC/Jose Antonio Novais 12Madrid 28040Spain Department of Biodiversity and Evolutionary Biology National Museum of Natural Sciences(CSIC)C/Jose Gutierrez Abascal 2Madrid 28006Spain

The demographic trend of a species depends on the dynamics of its local populations,which can be compromised by local or by global ***,the relevance of local and global phenomena has rarely been investigated ***,we tested whether local phenomena compromised a species'demographic trend using the Eurasian common lizard Zootoca vivipara,the terrestrial reptile exhibiting the widest geographic distribution,as a model *** analyzed the species'ancient demographic trend using genetic data from its 6 allopatric genetic clades and tested whether its demographic trend mainly depended on single clades or on global *** vivipara's effective population size increased since 2.3 million years ago and started to increase steeply and continuously from 0.531 million years *** growth rate exhibited 2 maxima,both occurring during global climatic changes and important vegetation changes on the northern *** population size and growth rate were negatively correlated with global surface temperatures,in line with global parameters driving long-term demographic *** vivipara's ancient demography was neither driven by a single clade,nor by the 2 clades that colonized huge geographic areas after the last *** low importance of local phenomena,suggests that the experimentally demonstrated high sensitivity of this species to short-term ecological changes is a response in order to cope with short-term and local *** suggests that what affected its long-term demographic trend the most,were not these local changes/responses,but rather the important and prolonged global climatic changes and important vegetation changes on the northern hemisphere,including the opening up of the forest by humans.

关键词： ancient demographic trend anthropological activity Bayesian skyline Plots early humans Eemian interglacial Eurasian common lizard mid-Brunhes event

Optimization of thermoacoustic refrigerator using response surface methodology

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Journal of Hydrodynamics 2013年第1期25卷 72-82页

作者： HARIHARAN N. M. sIVAsHANMUGAM P. KAsTHURIRENGAN s. Department of Chemical Engineering National Institute of Technology Centre for Cryogenic Technology Indian Institute of Science

Thermoacoustic refrigerator （TAR） converts acoustic waves into heat without any moving parts. The study presented here aims to optimize the parameters like frequency, stack position, stack length, and plate spacing involving in designing TAR using the Response surface Methodology （RsM）. A mathematical model is developed using the RsM based on the results obtained from DeltaEC software. For desired temperature difference of 40 K, optimized parameters suggested by the RsM are the frequency 254 Hz, stack position 0.108 m, stack length 0.08 m, and plate spacing 0.0005 m. The experiments were conducted with optimized parameters and simulations were performed using the Design Environment for Low-amplitude ThermoAcoustic Energy Conversion （DeltaEC） which showed similar results.

关键词： Design Environment for Low-amplitude ThermoAcoustic Energy Conversion (DeltaEC) optimization Response surface Methodology (RsM) temperature difference thermoacoustic refrigerator (TAR)

The whole day matters: Understanding 24-hour movement guideline adherence and relationships with health indicators across the lifespan

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Journal of sport and Health science 2020年第6期9卷 493-510页

作者： scott Rollo Olga Antsygina Mark s.Tremblay Healthy Active Living and Obesity Research Group Children’s Hospital of Eastern Ontario Research InstituteOttawaONK1H 8L1Canada Department of Pediatrics Faculty of MedicineUniversity of OttawaOttawaONK1H 8M5Canada Department of Health sciences Carleton UniversityOttawaONK1S 5B6Canada

Background:New research suggests that the composition(mix)of movement behaviors within a 24-h period may have important implications for health across the *** with this integrated movement behavior paradigm,a number of countries across the world have developed and released 24-h movement guidelines for specific age *** purpose of this systematic review was to examine the associations between the 24-h time-use composition of movement behaviors,or adherence to 24-h movement guidelines,and multiple health indicators across the ***:Five online databases(PsycINFO,PubMed,sPORTDiscus,Web of science,and Ovid MEDLINE)were searched for relevant peer-reviewed studies published between January 2015 and January 2020 that met the a priori inclusion criteria,with no study design *** methodological quality of research evidence for each individual study and for each health indicator was assessed by using a modified version of the Downs and Black ***:A total of 51 studies from 20 different countries met the inclusion criteria.A total of 31 studies examined adherence(meeting *** meeting)to 24-h movement guidelines,and 20 studies used compositional analyses to explore the 24-h time-use composition of movement *** indicated that meeting the 24-h movement guidelines were(1)not associated with adiposity among toddlers,(2)favorably associated with health-related quality of life,social-cognitive development,and behavioral and emotional problems among preschoolers,(3)favorably associated with global cognition,health-related quality of life,and healthy dietary patterns in children,and(4)favorably associated with adiposity,fitness,and cardiometabolic,mental,social,and emotional health among children and *** associations were also found between the composition of 24-h movement behaviors and indicators of(1)adiposity and bone and skeletal health among preschoolers,(2)health-related quality of life among child

关键词： Compositional analysis Movement behaviors Physical activity sedentary behavior sleep

Phosphorus Uptake from Rhizosphere soil by Two Wheat Cultivars

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Pedosphere 1998年第4期8卷 325-330页

作者： MAJIAN T．s．GAHOONIA 等 XingjiangInstituteofEcologyandGeography theChineseAcademyofSciences40SouthBeijingRoadUrumqi830011（C

Inorganic soil phosphorus extractable with sodium bicarbonate (NaHCO3-Pi), soil pH and root hairs length and density in the rhizosphere of two winter wheat cultivars (Triticum aestivum L. cv. shichun,sleipner) grown on a high pH Chinese silt loam (52.7 mg NaHCO3-Pi kg-1) and a Danish sandy loam (43.4mg NaHCO3-Pi kg-1) were studied to assess how these wheat cultivars differed in phoephorus *** rhizosphere soil pH of two wheat cultivars grown on the two soils were fairly unchanged with increasing distance from the root surface. However the root hairs of shichun were 2.1 times longer than those of sleipner. Root surface area (RsA) of shichun increased by 192% due to root hairs whereas root hairs of sleipner increased RsA by 68% only. Hence the root system of shichun was in contact with more soil than that of sleipner, even though sleipner had a longer root. Grown at the lower pH and level of NaHCO3-Pi in the Danish soil shichun absorbed more inorganic phosphorus than sleipner whereas at the higher pH and level of NaHCO3-Pi in the Chinese soil there was no phosphorus uptake difference between the two wheat cultivars.

关键词： inorganic phosphorus pH rhizosphere root hair wheat cultivar