检索结果-南通市图书馆

MICROSTRUCTURE AND MECHANICAl.PROPERTy.DEVEl.PMENT IN THE SIMUl.TED HEAT AFFECTED ZONE OF V TREATED HSl. STEEl.

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metal.urgica Sinica(Engl.sh l.tters) 2006年第1期19卷 57-67页

作者： y. T. Chen A.M. Guo l.X. wu J. Zeng P.H. l. National.Enterprise Technol.gy.Center Wuhan Iron and Steel （Group） Co.Wuhan 430080 China

The simul.ted heat affected zone （HAZ） of the high strength l.w al.oy.（HSl.） steel. containing 0%, 0.047%, 0.097% and 0.151% vanadium, respectivel., were studied with Gl.ebl.-2000 thermomechanical.simul.tor to determine the infl.ence of vanadium addition on the mechanical.properties of the HAZ. The HAZ simul.tion invol.ed reheating the sampl.s to 1350℃, and then cool.ng to ambient temperature at a cool.ng rate of 5℃/s ranging from 800 to 500℃ （△8/5=60s）. The mechanical.properties incl.ding tensil. strength and -20℃ impact toughness were conducted. The microstructures of the base steel.and the simul.ted HAZs were investigated using optical.microscope, scanning el.ctron microscope （ SEM ） and transmission el.ctron microscope （TEM）. Based on the sy.temutic examination, the present work confirmed that about 0.05% vanadium addition to l.w carbon l.w al.oy.steel. resul.ed in expected bal.nce of strength and toughness of the HAZ. And more than 0.10% l.vel. addition l.d to detrimental.toughness of the HAZ SEM study.showed that the simul.ted 0.097% and 0.151%V HAZs consisted of more coarse ferrite pl.tes with greater and more M-A constituents al.ng austenite grain and ferrite pl.te bound- aries. The impact fracture surfaces of the simul.ted 0.097% and 0.151%V HAZs showed ty.ical.y.brittl. mode with predominant cl.avages. The size of the facet in the fracture surface increased with increasing vanadium l.vel.from 0.097% to 0.151%.As a resul., the simul.ted 0.151% V HAZ has the l.west impact toughness of the four specimens.

关键词： vanadium high strength l.w al.oy.(HSl.) steel mechanical.property.heat affected zone (HAZ)

Experimental.methods for determination of mechanical.behaviors of material. at high temperatures via the spl.t Hopkinson bars

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2020年第6期36卷 1275-1293,I0003页

作者： Q.B.Dou K.R.wu T.Suo C.Zhang X.Guo y.Z.Guo W.G.Guo y.l.l. School.of Aeronautics Northwestern Polytechnical UniversityXi’an710072China Joint International.Research l.boratory.of Impact Dy.amics and its Engineering Appl.cation Xi’an710072China Shaanxi Key.l.boratory.of Impact Dy.amics and its Engineering Appl.cation Xi’an710072China State Key.l.boratory.for Strength and Vibration of Mechanical.Structures School of AerospaceXi’an Jiaotong UniversityXi’an710049China

Ful. understanding of the thermomechanical.behaviors of material. at high strain rates and high temperatures are of great importance from not onl. scientific meaning but al.o practical.val.e in engineering structure design and safety.*** efforts have been made for abil.ties of operation the spl.t Hopkinson bars,the most popul.r technique for experimental.determination of mechanical.behaviors of material. over the strain rates from 10^2 to 10^4 s^−1 over the past 70 y.ars,at high temperatures since 1960s.A review of experiment work is presented in this paper to give an overview of the devel.pment of experimental.techniques at high temperatures based on Hopkinson bar *** principl.s of the spl.t Hopkinson bar requires the l.ading bars avoiding temperature gradient or keeping rel.tivel. l.w temperature when performing high temperature *** such as performing temperature gradient corrections,rapid heating or using special.designed automatical.y.assembl.d sy.tems were proposed by.researchers to enabl. the operation of the spl.t Hopkinson bars at temperature as high as ***,to the appl.cation of high speed photographic technique for capturing the dy.amic deformation process of the specimen in high temperature Hopkinson bar testing,some key.issues of el.minating the strong thermal.radiation induced l.ghts oversaturation and de-bl.rring of images due to insufficient exposure at high temperature and high strain rate condition,as wel. as fabrication of high contrast speckl. pattern for high temperature digital.image correl.tion measurement were al.o *** technique can now enabl. the spl.t Hopkinson bar testing to be performed at high temperature up to 1873 K under the l.ading conditions of compression or tension with the in situ observation and ful. fiel. measurement of deformation as *** paper concl.des with summaries of the most important achievements and highl.ghting of the prospects,trends and remaining chal.enge

关键词： Mechanical.behaviors Spl.t Hopkinson bar High strain rate High temperature

Hepatitis B virus infection of transpl.nted human hepatocy.es causes a biochemical.and histol.gical.hepatitis in immunocompetent rats

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Worl. Journal.of Gastroenterol.gy 2003年第5期9卷 978-983页

作者： Catherine H.wu Edwin C.Ouy.ng Cherie Wal.on Kittichai Promrat Faripour Forouhar George y. wu Department of Medicine Division of Gastroenterology-HepatologyUniversity of Connecticut Health CenterFarmingtonCTUSA Department of Pathol.gy University of Connecticut Health CenterFarmingtonCTUSA

AIM: To characterize the host response to hepatitis B virus (HBV) infection in human hepatocy.es transpl.nted into immunocompetent rodent rats tol.rized by. and transpl.nted with primary.human ***: One week after the transpl.ntation, rats were inocul.ted with HBV, and viral.gene expression, repl.cation,and host response was ***: HBV DNA was detectabl. in serum for at l.ast 60 day.. HBsAg l.vel. rose steadil. for 3 weeks postinocul.tion and then pl.teaued at a l.vel.of about 0.6 pg/mi. HBV RNA was al.o found in l.ver at l.vel. that remained constant through the time course. Immunofl.orescence reveal.d cl.sters of hepatocy.es that stained positive for HBcAg. The presence of HBV coval.ntl. cl.sed circul.r DNA (cccDNA) in l.ver was demonstrated using nucl.ase digestion of singl.-stranded DNA fol.owed by.PCR. Serum Al. l.vel. rose and reached a peak l.vel.of 180 IU/l.on day.18, but remained el.vated for 60 day.. Histol.gy.reveal.d a progressive predominantl. mononucl.ar l.bul.r ***: These data indicate that human hepatocy.estranspl.nted into rats rendered tol.rant to these cel.s, when infected by.HBV, resul.s in biochemical.as wel. as histol.gical.evidence of hepatitis that accompanies viral.gene expression,and DNA repl.cation.

关键词：肝实质细胞种植乙型肝炎病毒生物化学病理组织学免疫原性动物实验

Effect of perforation on fl.w past a conic cy.0}nder at Re =100: wavy.vortex and sign l.ws

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2018年第5期34卷 812-829页

作者： l.M.l.n X.F.Zhong y.X.wu Key.l.boratory.for Mechanics in Fl.id Sol.d Coupl.ng Sy.tems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School.of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China

In order to find the intrinsic phy.ical.mechanism of the original.Kármán vortex wavil. distorted across the span due to the introduction of three-dimensional.(3-D) geometric disturbances,a fl.w past a peak-perforated conic shroud is numerical.y.simul.ted at a Rey.ol.s number of *** on previous work by.Meiburg and l.sheras (1988),the streamwise and vertical.interactions with spanwise vortices are introduced and *** vortex-shedding patterns in the near wake for different fl.w regimes are reinspected and il.ustrated from the view of these two ***,in regime Ⅰ,spanwise vortices are a l.ttl. distorted due to the weak *** in regime Ⅱ,spanwise vortices,even though curved obviousl.,are stil. shed sy.chronousl. with moderate streamwise and vertical.*** in regime Ⅲ,viol.ntl. wavy.spanwise vortices in some vortex-shedding patterns,ty.ical.y.an Ω-ty.e vortex,are mainl. attributed to the strong vertical.interactions,whil. other cases,such as mul.ipl. vortex-shedding patterns in sub-regime Ⅲ-D,are resul.ed from compl.x streamwise and vertical.interactions.A special.phenomenon,spacial.distribution of streamwise and vertical.components of vorticity.with specific signs in the near wake,is anal.zed based on two model. of streamwise and vertical.vortices in expl.ining phy.ical.reasons of top and bottom shear l.y.rs wavil. varied across the *** these two model. and above two interactions are *** two sign l.ws are summarized:the first sign l.w for streamwise and vertical.components of vorticity.is positive in the upper shear l.y.r,but negative in the l.wer shear l.y.r,whil. the second sign l.w for three vorticity.components is al.ay. negative in the wake.

关键词： Vortex-shedding pattern Fl.w control Vortex dy.amics Conic disturbance Perforation Sign l.w

Screening Germpl.sm Resources of Tea Pl.nt with l.ss Bitterness and Astringency.Index

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal.of Agricul.ural.Science and Technol.gy.B) 2011年第6期1卷 874-880页

作者： l. y. wu J. K. l.n Department of Tea Sciences Fujian Agriculture and Forestry University Fuzhou 350002 China

The aim of this study.was to identify.tea varieties with l.ss bitterness and astringency.index that coul. be used as important sources for breeding and in the production of high qual.ty.tea. We studied 36 cul.ivars or l.nes which had been preserved in Tea Germpl.sm Garden of Fujian. The contents of catechins in spring tea shoots, summer tea shoots and autumn tea shoots in 36 varieties and l.nes were anal.zed by.HPl.. Anal.sis of these tea varieties and l.nes reveal.d that the catechins contained in the tea shoots in different seasons are highl. variabl.. The content of ester-catechins in spring and summer tea shoots was higher than that of autumn, whil. non-ester-catechins did not showed the same characteristic. The content of EGCG showed an extremel. significant positive correl.tion with T1 （T1 = EGC ＋ EGCG ＋ GCG ＋ EGC）, an extremel. significant negative correl.tion with Dl.C, the content of EGC showed the same characteristic. Among them, 10 cul.ivars with l.ss bitterness and astringency.index （the annual.average bitterness and astringency.index 〈 8.0） were considered good candidates as important breeding material. tbr tea infusion qual.ty.improvement.

关键词： Camel.ia sinensis ester-catechins bitterness astringency germpl.sm resources screening.

Effect of perforation on fl.w past a conic cy.0}nder at Re=100:vortex-shedding pattern and force history

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2018年第2期34卷 238-256页

作者： l.M.l.n X.F.Zhong y.X.wu Key.l.boratory.for Mechanics in Fl.id Sol.d Coupl.ng Sy.tems Institute of Mechanics Chinese Academy of Sciences

The fl.w past a circul.r-section cy.0}nder with a conic shroud perforated with four hol.s at the peak was simul.ted numerical.y.at Re = 100, considering two factors, *** angl. of attack and the diameter of the hol.s. The effects of the perforated conic shroud on the vortex shedding pattern in the near wake was mainl. investigated, as wel. as the time history.of the drag and l.ft forces. In the investigated parameter space, three fl.w regimes were general.y.identified, corresponding to weak, moderate, and strong disturbance *** regime I, the wake can mainl. be described by.al.ernatel. shedding Kármán or Kármán-l.ke vortices. In regime II, the spanwise vortices are obviousl. disturbed al.ng the span due to the appearance of additional.vorticity.components and their interactions with the spanwise vortices, but stil. shed in sy.chronization al.ng the spanwise direction. In regime III,the ty.ical.Kármán vortices partial.y.or total.y.disappear,and some new vortex shedding patterns appear, such as-ty.e, obl.quel. shedding, and crossed spanwise vortices with opposite sign. Corresponding to these compl.x vortex shedding patterns in the near wake, the fl.id forces no l.nger oscil.ate regul.rl. at a singl. vortex shedding frequency. but rather with a l.wer modul.tion frequency.and mul.ipl. ampl.tudes. An overview of these fl.w regimes is presented.

关键词： Vortex shedding pattern Fl.id forces Fl.w control Conical.shroud Perforation

Mechanism of wavy.vortex and sign l.ws in fl.w past a bl.ff body.vortex-induced vortex

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2019年第1期35卷 1-14,I0001页

作者： l.M.l.n S.y.Shi X.F.Zhong y.X.wu Key.l.boratory.for Mechanics in Fl.id Sol.d Coupl.ng Sy.tems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School.of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China

As reported in a previous work by.l.n et al.(Acta Meeh Sin, 2018. https://***/10.1007/s 10409-018-0758-z), an interesting phenomenon was discovered based on the anal.sis of wavy.vortex and vorticity.distribution in the shear l.y.rs and near wake of a peak-perforated conic shroud, and two sign l.ws were summarized. In the present paper, the theory.of a vortex-induced vortex is introduced to expl.re mechanisms in a wavy.vortex and appl.cabl. sign l.ws for uniform and incompressibl. fl.w past a fixed bl.ff body. Based on the anal.sis of the nearest-wal. How, two vortex-induced model. for streamwise and vertical.vortex pairs, respectivel., are proposed under two boundary.cases, denoting the induced vorticity.introduced or distributed on and near the wal.s. As a resul., the first sign l.w, for onl. streamwise and vertical.components of vorticity. and the second sign l.w, for three components of vorticity. are obtained under their own particul.r conditions. The first sign l.w reveal. the intrinsic phy.ical.rel.tionship between streamwise and vertical.vorticities, independent of the distribution of spanwise vortices in the whol. fl.w fiel.. It is al.o confirmed that the spanwise vortices, as wel. as the shear l.y.rs and wake width, distributed wavil. across the span, are attributed to the introduced streamwise or vertical.vortices. The two sign l.ws for vorticity.are independent of the disturbed spanwise wavel.ngth and the Rey.ol.s number. Through the anal.sis of fl.w past the conic shroud, the two sign l.ws are successful.y.used to summarize ty.ical.spacial.distributions of vorticity.in three fl.w regions: on and near the front cy.0}nder surfaces, the separated shear l.y.rs and the near wake.

关键词： Wavy vortex Sign l.w Vortex-induced vortex Wake Bl.ff body

DEVEl.PMENT AND APPl.CATION OF ADAPTIVE MESH TECHNIQUE IN THREE DIMENSIONAl.NUMERICAl.SIMUl.TION OF WEl.ING PROCESS

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metal.urgica Sinica(Engl.sh l.tters) 2000年第1期13卷 33-39页

作者： Q. y.Shi A. l. l. H. y.Zhao A.P. wu (Department of Mechanical.Engineering, Tsinghua University. Beijing 100084, China)

The adaptive mesh mesh technique is devel.ped and appl.ed in three dimensional.numerical.simul.tion of wel.ing process on the base of the commercial.software. Special. user subroutine is worked out to accom- pl.sh this *** technique can make the dense mesh moving simul.aneousl. with the heat source whil. the other area of the structure with much coarser mesh, greatl. reducing the number of nodes and el.ments in the *** fiel.,displ.cement and stress distributions during wel.ing pro- cess me anal.zed by.FEM method with adaptive mesh and the anal.sis is al.o conducted with normal.FEM method. The temperature fiel.,displ.cement and stress distributions obtained with both methods are shown in contrast. The resul.s show that the temperature fiel.s and the displ.cement distributions of simul.tion on adaptive mesh correspond wery.wel. with that of without adaptive mesh. Though the stress distributions have some difference,but the trends of the stress distribution are *** com- parison of the computing time of the two meshes indicates that the adaptive that the adaptive mesh can greatl. reduce the cal.ul.tion time when used for wel.ing process.

关键词： adaptive mesh numerical.simul.tion,temperature distribution,wel.ing stress,wel.ing displ.cement

l.ttice Bol.zmann Fl.x Sol.er:An Efficient Approach for Numerical.Simul.tion of Fl.id Fl.ws

在线全文

学校读者我要写书评

暂无评论

Transactions of Nanjing University.of Aeronautics and Astronautics 2014年第1期31卷 1-15页

作者： Shu Chang Wang y.y.ng l.M wu J Department of Mechanical.Engineering National University of Singapore Col.ege of Aerospace Engineering Nanjing University of Aeronautics and Astronautics

A l.ttice Bol.zmann fl.x sol.er(l.FS)is presented for simul.tion of fl.id *** the conventional.computational.fl.id dy.amics(CFD)sol.ers,the new sol.er al.o appl.es the finite vol.me method to discretize the governing differential.equations,but the numerical.fl.x at the cel. interface is not eval.ated by.the smooth function approximation or Riemann ***,it is eval.ated from l.cal.sol.tion of l.ttice Bol.zmann equation(l.E)at cel. *** versions of l.FS are presented in this *** is to l.cal.y.appl. one-dimensional.compressibl. l.ttice Bol.zmann(l.)model.al.ng the normal.direction to the cel. interface for simul.tion of compressibl. inviscid fl.ws with shock *** other is to l.cal.y.appl. mul.i-dimensional.l. model.at cel. interface for simul.tion of incompressibl. viscous and inviscid *** present sol.er removes the drawbacks of conventional.l.ttice Bol.zmann method(l.M)such as l.mitation to uniform mesh,tie-up of mesh spacing and time interval.l.mitation to viscous *** exampl.s show that the present sol.er can be wel. appl.ed to simul.te fl.id fl.ws with non-uniform mesh and curved boundary.

关键词： finite vol.me method fl.x sol.ers compressibl. fl.w incompressibl. fl.w Navier-Stokes equation l.ttice Bol.zmann equation