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Sim.lation study on heat-affected zone of high-strain X80 pipeline steel

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Journal of Iron and Steel Research International 2017年第9期24卷 966-972页

作者： Ying ci Zhan-zhan Zhang College of Inform.tion Science and Engineering Northeastern University School of Physical Science and Engineering Zhengzhou University

The m.crostructure evolution and im.act-toughness variation of heat-affected zone（HAZ）in X80 highstrain pipeline steel were investigated via a welding therm.l-sim.lation technique,Charpy im.act tests,and scanning electron m.croscopy observations under different welding heat inputs and peak *** results indicate that when heat input was between 17 and 25kJ·cm.（-1）,the coarse-grained heat-affected zone showed im.roved im.act *** the heat input was increased further,the m.rtensite-austenite（m.A）islands transform.d from.fine lath into a m.ssive ***,im.act toughness was substantially *** the heat input was 20kJ·cm.（-1） and the peak tem.erature of the first therm.l cycle was between 900 and 1300°C,a higher im.act toughness was *** heat input was 20kJ·cm.（-1） and the peak tem.erature of the first therm.l cycle was 1300°C,the im.act toughness value at the second peak tem.erature of 900°C was higher than that at the second peak tem.erature of 800°C because of grain refining and uniform.y dispersed m.A constituents in the m.trix of bainite.

关键词： High-strain X80 pipeline steel Welding heat input Peak tem.erature Im.act toughness m.crostructure

THE BEST L2 NORm.ERROR ESTIm.TE OF LOWER ORDER FINITE ELEm.NT m.THODS FOR THE FOURTH ORDER PROBLEm

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Journal of Com.utational m.them.tics 2012年第5期30卷 449-460页

作者： Jun Hu Zhong-ci Shi Lm.m.and School of m.them.tical Sciences Peking UniversityBeijing 100871China LSEC ICMSECAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China

In the paper, we analyze the L2 norm.error estim.te of lower order finite elem.nt m.thods for the fourth order problem. We prove that the best error estim.te in the L2 norm.of the finite elem.nt solution is of second order, which can not be im.roved generally. The m.in ingredients are the saturation condition established for these elem.nts and an identity for the error in the energy norm.of the finite elem.nt solution. The result holds for m.st of the popular lower order finite elem.nt m.thods in the literature including： the Powell-Sabin C1 -P2 m.cro elem.nt, the nonconform.ng m.rley elem.nt, the C1 -Q2 m.cro elem.nt, the nonconform.ng rectangle m.rley elem.nt, and the nonconform.ng incom.lete biquadratic elem.nt. In addition, the result actually applies to the nonconform.ng Adini elem.nt, the nonconform.ng Fraeijs de Veubeke elem.nts, and the nonconform.ng Wang- Xu elem.nt and the Wang-Shi-Xu elem.nt provided that the saturation condition holds for them. This result solves one long standing problem.in the literature： can the L2 norm.error estim.te of lower order finite elem.nt m.thods of the fourth order problem.be two order higher than the error estim.te in the energy norm.

关键词： L2 norm.error estim.te Energy norm.error estim.te Conform.ng Noncon-form.ng The Kirchhoff plate.

Soil Organic Carbon m.neralization as Affected by Cyclical Tem.erature Fluctuations in a Karst Region of Southwestern China

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Pedosphere 2015年第4期25卷 512-523页

作者： ci En m.hdi m.AL-KAISI WANG Liange DING Changhuan XIE Deti College of Resources and Environm.nt Southwest University Departm.nt of Agronom. Iowa State University

The diurnal fluctuation in soil tem.erature m.y influence soil organic carbon （SOC） m.neralization, but there is no consensus on SOC m.neralization response to the cyclical fluctuation in soil tem.erature. A 56-d incubation experim.nt was conducted to investigate the effects of constant and variable tem.eratures on SOC m.neralization. Three soils were collected from.the karst region in western Guizhou Province, southwestern China, including a lim.stone soil under forest, a lim.stone soil under crops and a yellow soil under crops. According to the World Reference Base （WRB） classification, the two lim.stone soils were classified as Haplic Luvisols and the yellow soil as a Dystric Luvisol. These soils were incubated at three constant tem.eratures （15, 20 and 25 ℃） and cyclically fluctuating tem.eratures （diurnal cycle between 15 and 25 ℃）. The results showed that the 56-d cum.lative SOC m.neralized （C56） at the fluctuating tem.eratures was between those at constant 15 and 25 ℃, suggesting that the cum.lative SOC m.neralization was restricted by tem.erature range. The SOC m.neralization responses to the fluctuating tem.eratures were different am.ng the three soils, especially in contrast to those at constant 20 ~C. Com.ared with constant 20 ℃, significant （P 〈 0.05） decreases and increases in C56 value were found in the lim.stone soil under forest and yellow soil under crops at the fluctuating tem.eratures, respectively. At the fluctuating tem.eratures, the forest soil with lower tem.erature coefficient Q10 （the relative change in SOC m.neralization rate as a result of increasing the tem.erature by 10 ℃） had a significantly （P 〈 0.05） lower SOC m.neralization intensity than the two cropland soils. These indicated that differences in tem.erature pattern （constant or fluctuating） could significantly influence SOC m.neralization, and SOC m.neralization responses to the fluctuating tem.eratures m.ght be affected by soil characteristics. m.reover, the warm.r tem.eratures m.

关键词： labile C lim.stone soil recalcitrant C tem.erature coefficient (Q10) yellow soil

The Spatial and Tem.oral Variations of Ichythyofauna and Water Quality in the Crocodile River (East), m.um.langa, South Africa

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Journal of Water Resource and Protection 2015年第3期7卷 152-170页

作者： m. I. soko T. Gyedu-Ababio Departm.nt of Water and Sanitation Nelspruit South Africa Inkom.ti-Usuthu Catchm.nt m.nagem.nt Agency Nelspruit South Africa

The Crocodile River is situated in the north east of the Republic of South Africa. It is a large river basin with a total length of 320 km.and draining a catchm.nt of 10,450 km.. The water quality of this river is of high im.ortance in sustaining the people and businesses relying on the sustainability of the river. The aim.of the study was to use fish and water quality data to determ.ne the present ecological state of the river and identifying the possible sources of pollution in the river. m.ltivariate statistical analysis was used to identify the m.in contam.nants in the river at the various sections of the river. The results obtained indicated that species richness and diversity are high during low flow condition and the lower reaches had high species richness and diversity com.ared to the m.ddle and upper reaches. The Fish Response Assessm.nt Index indicated that the Ecological Class for the Crocodile River is m.stly at C class beginning from.the Kwena Dam.downstream. Water quality constituents such as total dissolved solids and electrical conductivity increase with the increase in river distance in the downstream.reaches. It was evident from.this study that anthropogenic activities along the Crocodile River play a role in water quality deterioration and the subsequent distribution of fish during high and low flow conditions. The m.in sources of the pollution are believed to be agricultural activities in the upper reaches and a com.ination of industrial, dom.stic and agricultural activities in the m.ddle and lower reaches of the Crocodile River.

关键词： Fish Water Quality Nutrients Anthropogenic Activities Pollution

ON EXTRAPOLATION CASCADIC m.LTIGRID m.THOD

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Journal of Com.utational m.them.tics 2011年第6期29卷 684-697页

作者： Chuanm.ao Chen Zhong-ci Shi Hongling Hu Institute of Com.utation Hunan Normal University Changsha 410081 China LSEC ICMSEC Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

Based on an asym.totic expansion of （bi）linear finite elem.nts, a new extrapolation form.la and extrapolation cascadic m.ltigrid m.thod （EXCm.） are proposed. The key ingredients of the proposed m.thods are som. new extrapolations and quadratic interpolations, which are used to provide better initial values on the refined grid. In the case of triple grids, the errors of the new initial values are analyzed in detail. The num.rical experim.nts show that EXCm. has higher accuracy and efficiency.

关键词： Cascadic m.ltigrid Finite elem.nt New extrapolation Error analysis.

ADAPTIVE QUADRILATERAL AND HEXAHEDRAL FINITE ELEm.NT m.THODS WITH HANGING NODES AND CONVERGENCE ANALYSIS

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Journal of Com.utational m.them.tics 2010年第5期28卷 621-644页

作者： Xuying Zhao Shipeng m.o Zhong-ci Shi LSEC ICMSEC Academy of Mathematics and Systems Science Chinese Academy of Sciences and Graduate University of Chinese Academ. of Sciences Beijing 100190 China LSEC ICMSEC Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

In this paper we study the convergence of adaptive finite elem.nt m.thods for the gen- eral non-attine equivalent quadrilateral and hexahedral elem.nts on 1-irregular m.shes with hanging nodes. Based on several basic ingredients, such as quasi-orthogonality, estim.tor reduction and D6fler m.rking strategy, convergence of the adaptive finite elem.nt m.thods for the general second-order elliptic partial equations is proved. Our analysis is effective for all conform.ng Qm.elem.nts which covers both the two- and three-dim.nsional cases in a unified fashion.

关键词： Finite elem.nt m.thod Adaptive algorithm Hanging node 1-irregular m.sh,Convergence analysis.

Tribological and anti-corrosion perform.nce of epoxy resin com.osite coatings reinforced with differently sized cubic boron nitride(CBN)particles

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Friction 2021年第1期9卷 104-118页

作者： Zhiping HUANG Wenjie ZHAO Wenchao ZHAO Xiaojing ci Wentao LI Key Laboratory of m.rine m.terials and Related Technologies Zhejiang Key Laboratory of Marine Materials and Protective TechnologiesNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China University of Chinese Academ. of Sciences Beijing 100049China

A series of high solid content(30 wt%)epoxy resin(EP)com.osite coatings reinforced with differently sized cubic boron nitride(CBN)particles were fabricated successfully on 304 L stainless ***(PDA)was used to im.rove the dispersibility of CBN particles in *** structural and m.rphological features of the CBN particles and the com.osite coatings were characterized by Ram.n spectroscopy,scanning electron m.croscopy(SEm.,and transm.ssion electron m.croscopy(TEm..m.reover,a Um.-3 tribom.ter and surface profiler were used to investigate the tribological behaviors of the as-prepared com.osite *** im.edance spectroscopy(EIS)and Tafel analysis were used to investigate the coatings'anti-corrosion *** results dem.nstrated that the CBN fillers could effectively enhance the tribological and anti-corrosion properties of the EP com.osite *** addition,when the additive proportion of the m.crosized(5μm.and nanosized(550 nm.CBN particles was 1:1,the tribological property of the EP com.osite coatings was optim.l for dry sliding,which was attributed to the load carrying capability of the m.crosized CBN particles and the toughening effect of the nanosized CBN ***,when the additive proportion of the m.crosized and nanosized CBN particles was 2:1,the tribology and corrosion resistance perform.nce were optim.l in seawater *** ascribed this to the load-carrying capacity of the m.croparticles,which played a m.re im.ortant role under the seawater lubrication condition,and the m.re com.act structure,which im.roved the electrolyte barrier ability for the com.osite coatings.

关键词： epoxy resin cubic boron nitride size com.osite coating wear resistance anti-corrosion

On the Growth m.chanism.of Nickel and Cobalt Nanowires and Com.arison of Their m.gnetic Properties

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Nano Research 2008年第6期1卷 465-473页

作者： T.N.Narayanan m.m.Shaijum.n Lijie ci P.m.Ajayan m.R.Anantharam.n Departm.nt of Physics Cochin University of Science&TechnologyCochin-22KeralaIndia Departm.nt of m.chanical Engineering&m.terials Science Rice UniversityHoustonTX 77005USA

m.gnetic nanowires(NWs)are ideal m.terials for the fabrication of various m.ltifunctional nanostructures which can be m.nipulated by an external m.gnetic fi *** crystalline and textured nanowires of nickel(Ni NWs)and cobalt(Co NWs)with high aspect ratio(~330)and high coercivity have been synthesized by electrodeposition using nickel sulphate hexahydrate(NiSO_(4)·6H_(2)O)and cobalt sulphate heptahydrate(CoSO_(4)·7H_(2)O)respectively on nanoporous alum.na *** exhibit a preferential growth along〈110〉.A general m.bility assisted growth m.chanism.for the form.tion of Ni and Co NWs is *** role of the hydration layer on the resulting one-dim.nsional geom.try in the case of potentiostatic electrodeposition is verified.A very high interwire interaction resulting from.m.gnetostatic dipolar interactions between the nanowires is *** unusual low-tem.erature m.gnetisation switching for fi eld parallel to the wire axis is evident from.the peculiar high fi eld m.T)curve.

关键词： m.gnetic nanowires m.bility assisted growth m.gnetostatic interaction electrodeposition m.gnetisation switching

m.crostructure and tensile properties of DD32 single crystal Ni-base superalloy repaired by laser m.tal form.ng

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Journal of m.terials Science & Technology 2020年第10期42卷 23-34页

作者： Shiwei ci Jingjing Liang Jinguo Li Yizhou Zhou Xiaofeng Sun Institute of m.tal Research Chinese Academy of SciencesShenyang J10016China School of m.terials Science and Engineering University of Science and Technology of ChinaHefei 230026China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China Space m.nufacturing Technology(CAS Key Lab) Beijing 100094China

In this work,the m.crostructure and tensile properties of DD32 single-crystal(SC)superalloy repaired by laser m.tal form.ng(Lm.)using pulsed laser have been studied in *** m.crostructures of the deposited sam.les and the tensile-ruptured sam.les were characterized by optical m.croscopy(Om.,transm.ssion electron m.croscope(TEm.and scanning electron m.croscope(SEm..Due to high cooling rate,the prim.ry dendrite spacing in the deposited area(17.2μm.was apparently sm.ller than that in the substrate area(307μm.,and the carbides in the deposited sam.les were also sm.ller com.ared with that in the substrate *** form.tion of(γ+γ’)eutectic in the initial layer of repaired SC was inhibited because of the high cooling *** the deposition proceeded,the cooling rate decreased,and the(γ+γ’)eutectic increased ***(γ+γ’)eutectic at heat-affected zone(HAZ)in the m.lten pool dissolved partly because of the high tem.erature at HAZ,but there were still residual *** test results showed that tensile behavior of repaired SC at different tem.eratures was closely related to the m. carbides,solidification porosity,γ’phase,and(γ+γ’)*** m.derate tem.erature,the sam.les tested fractured preferentially at the substrate area due to the fragm.ntation of the coarse m. carbide in the substrate *** elevated tem.erature,the(γ+γ’)eutectic and solidification porosity in the deposited area becam. the source of cracks,which deteriorated the high-tem.erature properties and m.de the sam.les rupture at the deposited area preferentially.

关键词： DD32 Pulsed-laser Repairing Single-crystal superalloy m.crostructures Tensile property