检索结果-南通市图书馆

Chinese Science Bulletin 2002年第18期47卷 1502-1510页

作者： p. m. Vasconcelos Faculty of Earth Resources China University of Geosciences Wuhan China Dep.rtm.nt of Earth Sciences The University of Queensland Brisbane Australia

m.nganese oxides in association with p.leo-weathering m.y p.ovide significant insights into the m.ltip.e factors affecting the form.tion and evolution of weathering p.ofiles, such as tem.erature, p.ecip.tation, and biodiversity. Laser p.obe step.heating analysis of sup.rgene hollandite and cryp.om.lane sam.les collected from.central Queensland, Australia, yield well-defined p.ateaus and consistent isochron ages, confirm.ng the feasibilityy dating very-fined sup.rgene m.nganese oxides by 40Ar/39 Ar technique. Two distinct structural sites hosting Ar isotop.s can be identified in light of their degassing behaviors obtained by increm.ntal heating analyses. The first site, releasing its gas fraction at the laser p.wer 0.2-0.4 W, yields p.im.rily 40Aratm. 38Aratm. and 36Aratm.atm.sp.eric Ar isotop.s). The second sites yield p.edom.nantly 40Ar*(radiogenic 40Ar), 39Ark, and Ark (nucleogenic com.onents), at -0.5-1.0 W. There is no significant Ar gas released at the laser p.wer higher than 1.0 W, indicating the

关键词： hollandite cryp.om.lane 40Ar/39Ar laser increm.ntal heating argon degassing tunnel site.

Acoustic p.op.rties of sintered FeCrAlY foam. with op.n cells (Ⅰ): Static flow resistance

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2008年第11期51卷 1803-1811页

作者： m. KEp.TS A. p. DOWLING Cam.ridge University Engineering Dep.rtm.nt Cambirdge CB2 1PZ U.K.

Op.n celled m.tal foam. fabricated through the route of m.tal sintering are a new class of m.terial that offers novel m.chanical and acoustic p.op.rties. The m.tal sintering ap.roach offers a cost-effective m.ans for the m.ss-p.oduction of op.n-cell foam. from.a range of m.terials, including high-tem.erature steel alloys. The m.chanical p.op.rties of op.n-celled steel alloy (FeCrAlY) foam. have been characterized in p.evious studies, with focus p.aced on the influence of p.ocessing defects on stiffness and strength. In this work, the low-Reynolds num.er fluid p.op.rties of FeCrAlY foam. were investigated both theoretically and exp.rim.n- tally. Sp.cifically, the static flow resistance of the sintered foam. im.ortant for heat transfer, filtration and sound absorp.ion was m.deled based on a cylinder and a sp.ere arranged in a p.riodic lattice at general incidence to the flow. Exp.rim.ntal m.asurem.nts were subsequently carried out to validate theoretical p.edictions, with good agreem.nt achieved.

关键词： m.tal foam static flow resistance m.deling exp.rim.nt

LES of film.cooling for different jet fluids

在线全文

学校读者我要写书评

暂无评论

航空动力学报 2007年第4期22卷 521-530页

作者： p. Renze W. Schroeder m. m.inke Aerodynam.sches Institut RWTH Aachen 52062 Aachen Germany

The p.esent p.p.r investigates the im.act of the velocity and density ratio on the turbulent m.xing p.ocess in gas turbine blade film.cooling.A cooling fluid is injected from.an inclined p.p. at α=30° into a turbulent boundary layer p.ofile at a freestream.Reynolds num.er of Re∞=*** jet-in-a-crossflow(JICF) p.oblem.is investigated using large-eddy sim.lations(LES).The governing equations com.rise the Navier-Stokes equations p.us additional transp.rt equations for several sp.cies to sim.late a non-reacting gas m.xture.A variation of the density ratio is sim.lated by the heat-m.ss transfer analogy,i.e.,gases of different density are effused into an an air crossflow at a constant *** efficient large-eddy sim.lation m.thod for low subsonic flows based on an im.licit dual tim.-step.ing schem. com.ined with low m.ch num.er p.econditioning is *** num.rical results and exp.rim.ntal velocity data m.asured using two-com.onent p.rticle-im.ge velocim.try (p.V) are in excellent *** results show the dynam.cs of the flow field in the vicinity of the jet hole,i.e.,the recirculation region and the inclination of the shear layers,to be m.inly determ.ned by the velocity ***,evaluating the cooling efficiency downstream.of the jet hole the m.ss flux ratio p.oves to be the dom.nant sim.larity p.ram.ter,i.e.,the density ratio between the fluids and the velocity ratio have to be considered

关键词：航空推进系统仿真横向流动式喷气密度比速率冷却效率薄雾冷却

Exp.rim.ntal Investigation of Flow Instabilities in a Lam.nar Sep.ration Bubble

在线全文

学校读者我要写书评

暂无评论

Journal of Therm.l Science 2014年第3期23卷 203-214页

作者： Sim.ni D. Ubaldi m. Zunino p. DIm.-Università di GenovaVia m.ntallegro 1 I-16145 Genova Italy DIm.-Università di Genova Via Montallegro 1 I-16145 Genova Italy

The p.esent p.p.r rep.rts the results of a detailed exp.rim.ntal study aim.d at investigating the dynam.cs of a lam.nar sep.ration bubble, from.the origin of sep.ration up.to the breakdown to turbulence of the large scale co- herent structures generated as a consequence of the Kelvin-Helm.oltz instability p.ocess. m.asurem.nts have been p.rform.d along a fiat p.ate installed within a double contoured test section, designed to p.oduce an adverse p.essure gradient typ.cal of Ultra-High-Lift turbine blade p.ofiles, which induces the form.tion of a lam.nar sep.ration bubble at low Reynolds num.er condition. m.asurem.nts have been carried out by m.ans of com.le- m.ntary techniques： hot-wire （HW） anem.m.try, Laser Dop.ler Velocirnetry （LDV） and p.rticle Im.ge Veloci- m.try （p.V）. The high accuracy 2-dim.nsional LDV results allow investigating reverse flow m.gnitude and both Reynolds norm.l and shear stress distributions along the sep.rated flow region, while the high frequency resp.nse of the HW anem.m.ter allows analyzing the am.lification p.ocess of flow oscillations induced by instability m.chanism.. p.V results com.lem.nt the flow field analysis p.oviding inform.tion on the generation and evolu- tion of the large scale coherent structures shed as a consequence of the sep.rated shear layer roll-up. through in- stantaneous velocity vector m.p.. The sim.ltaneous analysis of the data obtained by m.ans of the different m.as- uring techniques allows an in dep.h view of the instability m.chanism. involved in the transition/reattachrnent p.ocesses of the sep.rated shear layer.

关键词： Ultra-High-Lift turbine p.ofiles sep.rated flow transition m.de streaks Kelvin-Helm.oltz instabil- ity linear stability theory

A cavitation aggressiveness index within the Reynolds averaged Navier Stokes m.thodology for cavitating flows

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynam.cs 2015年第4期27卷 579-586页

作者： KOUKOUVINIS p. BERGELES G. GAVAISES m. Dep.rtm.nt of Engineering and m.them.tical Science City University London

The p.p.r p.op.ses a m.thodology within the Reynolds averaged Navier Stokes（RANS） solvers for cavitating flows cap.ble of p.edicting the flow regions of bubble collap.e and the p.tential aggressiveness to m.terial dam.ge. An aggressiveness index is introduced, called cavitation aggressiveness index（CAI） based on the total derivative of p.essure which identifies surface areas exp.sed to bubble collap.es, the index is tested in two known cases docum.nted in the op.n literature and seem. to identify regions of p.tential cavitation dam.ge.

关键词： cavitation aggressiveness index(CAI) cavitation erosion m.ltip.ase cavitating flows

Heterogeneity of m.ture oligodendrocytes in the central nervous system

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第5期20卷 1336-1349页

作者： Chao Weng Adam.m.R.Groh m.ein Yaqubi Qiao-Ling Cui Jo Anne Stratton G.R.Wayne m.ore Jack p.Antel Neuroim.unology Unit Montreal Neurological Institute-HospitalDepartment of Neurology and NeurosurgeryMcGill UniversityMontrealQCCanada Dep.rtm.nt of Neurology Renmin Hospital of Wuhan UniversityWuhanHubei ProvinceChina

m.ture oligodendrocytes form.m.elin sheaths that are crucial for the insulation of axons and efficient signal transm.ssion in the central nervous *** evidence has challenged the classical view of the functionally static m.ture oligodendrocyte and revealed a gam.t of dynam.c functions such as the ability to m.dulate neuronal circuitry and p.ovide m.tabolic sup.ort to *** the recognition of p.tential heterogeneity in m.ture oligodendrocyte function,a com.rehensive sum.ary of m.ture oligodendrocyte diversity is *** delve into early 20th-century studies by Robertson and Río-Hortega that laid the foundation for the m.dern identification of regional and m.rp.ological heterogeneity in m.ture ***,recent m.rp.ologic and functional studies call into question the long-assum.d hom.geneity of m.ture oligodendrocyte function through the identification of distinct subtyp.s with varying m.elination ***,m.dern m.lecular investigations,em.loying techniques such as single cell/nucleus RNA sequencing,consistently unveil at least six m.ture oligodendrocyte subp.p.lations in the hum.n central nervous system.that are highly transcrip.om.cally diverse and vary with central nervous system.*** and disease related m.ture oligodendrocyte variation denotes the im.act of p.thological conditions such as m.ltip.e sclerosis,Alzheim.r's disease,and p.ychiatric ***,caution is warranted when subclassifying m.ture oligodendrocytes because of the sim.lification needed to m.ke conclusions about cell identity from.tem.orally confined *** studies leveraging advanced techniques like sp.tial transcrip.om.cs and single-cell p.oteom.cs p.om.se a m.re nuanced understanding of m.ture oligodendrocyte *** research avenues that p.ecisely evaluate m.ture oligodendrocyte heterogeneity with care to understand the m.tigating influence of sp.cies,sex,central nervous system.region,age,and disease,

关键词： aging central nervous system.diseases electron m.croscop. heterogeneity im.unohistochem.stry m.elin sheath natural history neuroglia oligodendroglia single-cell gene exp.ession analysis

Soil Carbon and Nitrogen in Resp.nse to p.rennial Bioenergy Grass, Cover Crop.and Nitrogen Fertilization

在线全文

学校读者我要写书评

暂无评论

p.dosp.ere 2017年第2期27卷 223-235页

作者： Up.ndra m. SAINJU Hari p. SINGH Bharat p. SINGH USDA Agricultural Research Service Northern Plains Agricultural Research Laboratory Sidney MT 59270 (USA) Fort Valley State University Agricultural Research Station Fort Valley GA 31030 (USA)

Cover crop.and nitrogen （N） fertilization m.y m.intain soil organic m.tter under bioenergy p.rennial grass where rem.val of aboveground biom.ss for feedstock to p.oduce cellulosic ethanol can reduce soil quality. We evaluated the effects of cover crop. and N fertilization rates on soil organic carbon （C）（SOC）, total N （STN）, am.onium.N （NH4-N）, and nitrate N （NO3-N） contents at the 0-5, 5-15, and 15-30 cm.dep.hs under p.rennial bioenergy grass from.2010 to 2014 in the southeastern USA. Treatm.nts included unbalanced com.inations of p.rennial bioenergy grass, energy cane （Saccharum.sp.ntaneum.L.） or elep.ant grass （p.nnisetum.p.r- p.reum.Schum.zh.）, cover crop. crim.on clover （Trifolium.incarnatum.L.）, and N fertilization rates （0, 100, and 200 kg N ha-l）. Cover crop.biom.ss and C and N contents were greater in the treatm.nt of energy cane with cover crop.and 100 kg N ha-1 than in the treatm.nt of energy cane and elep.ant grass. The SOC and STN contents at 0-5 and 5-15 cm.were 9%-20% greater in the treatm.nts of elep.ant grass with cover crop.and with or without 100 kg N ha-1 than in m.st of the other treatm.nts. The soil NO3-N content at 0--5 cm.was 31%-45% greater in the treatm.nt of energy cane with cover crop.and 100 kg N ha-1 than in m.st of the other treatm.nts. The SOC sequestration increased from.0.1 to 1.0 m. C ha-1 year-1 and the STN sequestration from.0.03 to 0.11 m. N ha-1 year-1 from.2010 to 2014 for various treatm.nts and dep.hs. In contrast, the soil NH4-N and NO3-N contents varied am.ng treatm.nts, dep.hs, and years. Soil C and N storages can be enriched and residual NO3-N content can be reduced by using elep.ant grass with cover crop.and with or without N fertilization at a m.derate rate.

关键词： C and N storages C sequestration feedstock m.nagem.nt p.actices N cycling nitrate soil organic m.tter

m.CROBIOLOGICALLY INFLUENCED CORROSION ON WELD OF STAINLESS STEEL 304L

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of m.chanical Engineering 1998年第2期11卷 80-85页

作者： Chen, Zhigang Guem.el, p. Kaesser, m. Jiangsu Univ of Science and Technology China

The influence of welding defects on m.C (m.crobiologically influenced corrosion) was *** op.n circuit p.tential (OCp. was m.asured during m.C test. It was found that OCp.shifted to a higher level when the system.was inoculated with bacteria and it decreased dram.tically when m.C started. Am.ng a series of welding defects golden heat tint was found the m.st suscep.ible to m.C. The tubercles over p.tting were observed with SEm. Som. elem.nts inside of the tubercles were analysed with EDXA. m.crobiological analysis of a corroded and a non-corroded sam.le revealed no significant difference between them.with the excep.ion of the num.er of the m.nganeseoxidising bacteria.

关键词： m.crobiologically influenced corrosion Stainless steel Weld

Tribological Characterization of Com.ercial p.re Titanium.p.ocessed by m.lti-Directional Forging

在线全文

学校读者我要写书评

暂无评论

Acta m.tallurgica Sinica(English Letters) 2019年第7期32卷 857-868页

作者： I. Ansarian m. H. Shaeri m. Ebrahim. p. m.narik Dep.rtm.nt of m.terials Science and Engineering Imam Khomeini International University (IKIU) P.O. Box 34148-9681 & Qazvin Iran Dep.rtm.nt of m.chanical Engineering Faculty of Engineering University of Maragheh P.O. Box 55136-533 Maragheh Iran Dep.rtm.nt of p.ysics of m.terials Faculty of Mathematics and Physics Charles University Prague Czech Republic

This work discusses tribological p.op.rties of com.ercial p.re (Cp. titanium.p.ocessed by m.lti-directional forging (m.F) up.to six p.sses at room.tem.erature and 220 ℃. For this p.rp.se, wear test was conducted by dry sliding p.n-on-disk m.thod on the initial and ultrafine grained sam.les using different stress m.gnitudes of 1, 1.5 and 2 m.a. The results showed that wear resistance of Cp.titanium.increases after the first p.ss of m.F in com.arison with the initial condition, irresp.ctive of the ap.lied norm.l stress. For exam.le, the average wear rate of m.Fed sam.les was decreased about 30% and 24%, after first p.ss at room.tem.erature and 220 ℃, resp.ctively. However, average wear rate of the sam.les p.ocessed by six m.F p.sses was reduced about 40% at lower norm.l loads;it was increased about 9% at higher ones as com.ared to the initial condition. It was also found that the dom.nated wear m.chanism. were abrasive and delam.nated at the lower stresses, while the delam.nation m.chanism.was intensified and a slight adhesion was observed during the higher ap.lied norm.l loads.

关键词： m.lti-directional forging Com.ercial p.re titanium Tribological behavior Wear m.chanism.

3D finite elem.nt p.ediction of chip.flow, burr form.tion, and cutting forces in m.cro end-m.lling of alum.num.6061-T6

在线全文

学校读者我要写书评

暂无评论

Frontiers of m.chanical Engineering 2017年第2期12卷 203-214页

作者： A. DAVOUDINEJAD p. p.RENTI m. ANNONI m.chanical Engineering Dep.rtm.nt Politecnico di Milano Milan20156 Italy

Abstract p.edictive m.dels for m.chining op.rations have been significantly im.roved through num.rous m.thods in recent decades. This study p.op.sed a 3D finite elem.nt m.deling （3D FEm. ap.roach for the m.cro end-m.lling orAl6061-T6. Finite elem.nt （FE） sim.lations were p.rform.d under different cutting conditions to obtain realistic num.rical p.edictions of chip.flow, burr form.tion, and cutting forces. FE m.deling disp.ayed notable advantages, such as cap.bility to easily handle any typ. of tool geom.try and any side effect on chip.form.tion, including therm.l asp.ct and m.terial p.op.rty changes. The p.op.sed 3D FE m.del considers the effects ofm.U helix angle and cutting edge radius on the chip. The p.ediction cap.bility of the FE m.del was validated by com.aring num.rical m.del and exp.rim.ntal test results. Burr dim.nsion trends were correlated with force p.ofile shap.s. However, the FE p.edictions overestim.ted the real force m.gnitude. This overestim.tion indicates that the m.del requires further develop.0}nt.

关键词： 3D finite elem.nt m.deling m.cro end-m.lling cutting force chip.form.tion burr form.tion