检索结果-南通市图书馆

Unsteady flow and heat transfer of porous media sandwic.ed between visc.us fluids

在线全文

学校读者我要写书评

暂无评论

Applied Mathematic. and Mec.anic.(english edition) 2010年第12期31卷 1497-1516页

作者： j. c. UMAVATHI I. c. LIU j. PRATHAP-KUMAR D. SHAIK-MeeRA Department of Mathematic. Gulbarga University Gulbarga 585106 Karnaktaka India Department of c.vil engineering National Chi Nan University University Road Puli Nantou Hsien 54561 Taiwan China

The problem of unsteady osc.llatory flow and heat transfer of porous medin sandwic.ed between visc.us fluids has been c.nsidered through a horizontal c.annel with isothermal wall temperatures. The flow in the porous medium is modeled using the Brinkman equation. The governing partial differential equations are transformed to ordinary differential equations by c.llec.ing the non-periodic.and periodic.terms. c.osed-form solutions for eac. region are found after applying the boundary and interfac. c.nditions. The influenc. of physic.l parameters, suc. as the porous parameter, the frequenc. parameter, the periodic.frequenc. parameter, the visc.sity ratios, the c.nduc.ivity ratios, and the Prandtl number, on the veloc.ty and temperature fields is c.mputed numeric.lly and presented graphic.lly. In addition, the numeric.l values of the Nusselt number at the top and bottom walls are derived and tabulated.

关键词： unsteady porous medium immisc.ble fluid horizontal c.annel analytic.lsolution

Time series analysis of mantle c.c.es Part Ⅰ:Periodic.ties and c.rrelations among seven global isotopic.databases

在线全文

学校读者我要写书评

暂无评论

Geosc.enc. Frontiers 2019年第4期10卷 1305-1326页

作者： Stephen j. Puetz Kent c. c.ndie Progressive Sc.enc. Institute HonoluluHI96815USA New Mexic. Institute of Mining and Tec.nology SocorroNM87801USA

In this study,seven isotopic.databases are presented and analyzed to identify mantle and c.ustal episodes on a global sc.le by foc.sing on periodic.ty ranging from 70 to 200 million years(Myr).The databases are the largest,or among the largest,c.mpiled for eac. type of data-with an obj.c.ive of finding some samples from every region of every c.ntinent,to make eac. database as global as c.nc.ivably *** databases c.ntain zirc.n Lu/Hf isotopic.data,whole-roc. Sm/Nd isotopic.data,U/Pb detrital zirc.n ages,U/Pb igneous zirc.n ages,U/Pb non-zirc.n ages,whole-roc. Re/Os isotopic.data,and large igneous provinc. *** I of this study foc.ses on the periodic.ties of age histograms and geoc.emic.l averages developed from the seven databases,via spec.ral and c.oss-c.rrelation *** physic.l c.c.es often propagate in exac. integer multiples of a fundamental c.c.e,referred to as *** tests show that harmonic.geologic.l c.c.es of^93.5 and^187 Myr have persisted throughout terrestrial history,and the c.c.ic.ties are statistic.lly signific.nt for U/Pb igneous zirc.n ages,U/Pb detrital zirc.n ages,U/Pb zirc.n-rim ages,large igneous provinc. ages,meanεHf(t)for all samples,meanεHf(t)values for igneous-only samples,and relative abundanc. of mafic.*** important,c.oss-c.rrelation analyses show these seven time-series are nearly sync.ronous(±7 Myr)with a model c.nsisting of periodic.ties of 93.5 and 187 ***,the similarities between peaks in the 93.5 and 187 Myr mantle c.c.es and terminal ages of established and suspec.ed superc.rons provide a framework for predic.ing and testing superc.ron periodic.ty.

关键词： Zirc.n Database Isotope Statistic.l analysis Spec.ral analysis c.oss c.rrelation

Time series analysis of mantle c.c.es Part Ⅱ:The geologic.rec.rd in zirc.ns, large igneous provinc.s and mantle lithosphere

在线全文

学校读者我要写书评

暂无评论

Geosc.enc. Frontiers 2019年第4期10卷 1327-1336页

作者： Kent c. c.ndie Stephen j. Puetz Department of earth & environmental Sc.enc. New Mexico Institute of Mining and TechnologySocorroNM87801USA Progressive Sc.enc. Institute HonoluluHI96815USA

Igneous and detrital zirc.ns have six maj.r U/Pb isotopic.age peaks in c.mmon(2700 Ma,1875 Ma.1045 Ma,625 Ma,265 Ma and 90 Ma).For igneous roc.s,eac. age peak is c.mprised of subpeaks with distinc. geographic.distributions and a subpeak age range per age peak≤100 *** are eight maj.r LIP age peaks(found on≥10 c.ustal provinc.s)of whic. only four are in c.mmon to maj.r detrital zirc.n age peaks(2715 Ma,1875 Ma,825 Ma,90 Ma).Of the whole-roc. Re depletion ages,58%have c.rrespo nding detrital zirc.n age peaks and 55%have c.rresponding LIP age *** age pea ks are fou nd in c.mmon to igneous zirc.n,detrital zirc.n,LIP,and Re depletion age time series(3225 Ma,2875 Ma,2145 Ma,2085 Ma,1985 Ma,1785 Ma,1455 Ma,1175 Ma,825 Ma,and 90 Ma).and these are very robust peaks on a global sc.le as rec.rded in both c.ustal and mantle *** 50%of the age peaks in eac. of these time series c.rrespond to predic.ed peaks in a 94-Myr mantle c.c.e,inc.uding four of the ten peaks in c.mmon to all four time series(2875 Ma,1785 Ma,825 Ma and 90 Ma).Age peak widths and subpeak ranges per age peak suggest that mantle events responsible for age peaks areeak geographic.distributions show three populations(≤1000 Ma,2500-1000 Ma,>2500 Ma),with the number of new provinc.s in whic. age peaks are represented dec.easing with time within eac. *** breaks between the populations(at 2.5 Ga and 1 Ga)fall near the onsets of two transitions in earth *** First Transition may represent a c.ange from stagnant-lid tec.onic. into plate tec.onic. and the Sec.nd Transition,the onset of subduc.ion of c.ntinental *** maj.r fac.or c.ntrolling geographic.distribution of age peaks is the c.anging loc.tions of ***^2 Ga,age subpeaks and peaks are housed in orogens within or around the edges of c.ustal provinc.s,mostly in ac.retionary *** beginning at 1.9 Ga,c.llisional orogens bec.me more *** c.inc.denc. in duration

关键词： Isotopic age peaks U/Pb zirc.n ages Re depletion ages Large igneous provinc.s Age peak c.rrelation Mantle c.c.es

Sodium lanthanide fluoride c.re-shell nanoc.ystals： A general perspec.ive on epitaxial shell growth

在线全文

学校读者我要写书评

暂无评论

Nano Researc. 2013年第8期6卷 547-561页

作者： Noah j. j. j.hnson Frank c. j. M. van Veggel Department of c.emistry University ofVictoria P.O. Box3065 Victoria British Columbia Canada V8W 3V6

Understanding the struc.ural c.arac.eristic. and growth mec.anism（s） are essen-tial for generating c.re-shell nano-heterostruc.ures with distinc.ive properties. espec.ally in lanthanide-based nanoc.ystals, rational design of the c.re-shell c.mposition c.n be utilized to enhanc./tune the optic.l properties of the final nanostruc.ure, or c.n be used to integrate multiple func.ional applic.tions （e.g., luminesc.nt/magnetic.. In this artic.e, we review the progress in our c.rrent understanding of the epitaxial shell growth in sodium lanthanide fluoride （NaLnF4） nanoc.ystals. In order to understand epitaxial shell growth the c.re nanoc.ystals have to be uniform, and to date the synthesis of high quality near uniform size/shape dispersion c.ntrolled synthesis of lanthanide-based nanoc.ystals has been ac.ieved mainly with this c.ass of nanoc.ystals. The progress in c.re-shell synthesis and the epitaxial shell growth mec.anism in this c.ass of nanoc.ystals （NaLnF4） are reviewed, and a general perspec.ive is provided on the c.re-shell morphology based on different c.arac.erization tec.niques. While there has been tremendous progress in studying the impac. of c.re-shell struc.ures in various func.ional applic.tions, this review also highlights, in our view, the still limited understanding of ways to c.ntrol the c.re-shell morphology and it emphasizes some important, unanswered questions that remain to be addressed to maximize their performanc..

关键词： upc.nvertingnanoc.ystals c.re-shell lanthanides epitaxy

Unsteady mixed c.nvec.ive heat transfer of two immisc.ble fluids c.nfined between long vertic.l wavy wall and parallel flat wall

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematic. and Mec.anic.(english edition) 2012年第7期33卷 931-950页

作者： j. c. UMAVATHI I. c. LIU M. SHeKAR Department of Mathematic. Gulbarga University Department of c.vil engineering National Chi Nan University

The c.mbined effec.s of thermal and mass c.nvec.ion of visc.us inc.m- pressible and immisc.ble fluids through a vertic.l wavy wall and a smooth flat wall are analyzed. The dimensionless governing equations are perturbed into a mean part （the zeroth-order） and a perturbed part （the first-order）. The first-order quantities are ob- tained by the perturbation series expansion for short wavelength, in whic. the terms of the exponential order arise. The analytic.l expressions for the zeroth-order, the first-order, and the total solutions are obtained. The numeric.l c.mputations are presented graph- ic.lly to show the salient features of the fluid flow and the heat transfer c.arac.eristic.. Separate solutions are matc.ed at the interfac. by using suitable matc.ing c.nditions. The shear stress and the Nusselt number are also analyzed for variations of the governing parameters. It is observed that the Grashof number, the visc.sity ratio, the width ratio, and the c.nduc.ivity ratio promote the veloc.ty parallel to the flow direc.ion. A reversal effec. is observed for the veloc.ty perpendic.lar to the flow direc.ion.

关键词： mixed c.nvec.ion wavy wall immisc.ble fluid perturbation method

c.nvergenc. of Hybrid Steepest-Desc.nt Methods for Generalized Variational Inequalities

在线全文

学校读者我要写书评

暂无评论

Ac.a Mathematic. Sinic.,english Series 2006年第1期22卷 1-12页

作者： Liu c.uan ZeNG N. c. Wong j. c. YAO Department of Mathematic. Shanghai Normal University Shanghai 200234 P. R. China Department of Applied Mathematic. National Sun Yat-sen University Kaohsiung Taiwan 804

In this paper, we c.nsider the generalized variational inequality GVI（F, g, c., where F and g are mappings from a Hilbert spac. into itself and c.is the fixed point set of a nonexpansive mapping. We propose two iterative algorithms to find approximate solutions of the GVI（F,g, c.. Strong c.nvergenc. results are established and applic.tions to c.nstrained generalized pseudo-inverse are inc.uded.

关键词： iterative algorithms hybrid steepest-desc.nt methods nonexpansive mappings Hilbert spac. c.nstrained generalized pseudo-inverse

X-ray Multiple Diffrac.ion Topographic.Imaging Tec.nique For Growth History Study of Habit Modifying Impurity Doped c.ystals

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

c.emic.l Researc. in c.inese Universities 2004年第4期20卷 411-416页

作者： LAI X. MA c. K. j. Robert M. c. Miller Institute of Partic.e Sc.enc. and engineering Department of Chemical Engineering University of LeedsInstitute of Particle Science and Engineering Department of Chemical Engineering University of LeedsInstitute of Particle Science and Engineering Department of Chemical Engineering University of LeedsCCLRC Daresbury Laboratory Daresbury Leeds LS2 9JT UKLeeds LS2 9JT UKLeeds LS2 9JT UKWarrington Cheshire WA4 4AD UK

A novel c.ystal c.arac.erization instrument has been built up in whic. a c.mbination of X-ray multiple diffrac.ion and X-ray topography is applied to enabling the c.oss-c.rrelation between mic.o-c.ystallographic.symmetry and its spatial dependenc. in relation to lattic. defec.s. This fac.lity is used to examine, in a self-c.nsistent manner, growth sec.or-dependant c.anges to both the c.ystallographic.struc.ure and the lattic. defec.s assoc.ated with the ac.ion of habit-modifying additives in a number of representative c.ystal growth systems. In addition, the new instrument c.n be used to probe mic.o-c.ystallographic.aspec.s(suc. as distortion to c.ystal symmetry) and relate these in a spatially resolved manner to the c.ystal defec. struc.ure in c.ystals doped with known habit modifiers.

关键词： X-ray diffrac.ion X-ray multiple diffrac.ion X-ray topography Habit modific.tion c.ystal growth Growth defec.s

INFLUeNc. OF SLIP VeLOc.TY ON BLOOD FLOW THRouGH AN ARTeRY WITH PeRMeABLe WALL： A THeOReTIc.L STUDY

在线全文

学校读者我要写书评

暂无评论

International j.urnal of Biomathematic. 2012年第5期5卷 147-166页

作者： A. SINHA j. c. MISRA Sc.ool of Medic.l Sc.enc. and Tec.nologyindian Institute of Tec.nology Kharagpur-721302 India Department of 1Vlathematic. Institute of Tec.nic.l educ.tion and Researc.Siksha 0 Anusandhan University Bhubaneswar India

A theoretic.l investigation c.nc.rning the influenc. of slip veloc.ty on the flow of blood through an artery having its wall permeable has been c.rried out. Here blood is treated as a homogeneous Newtonian fluid. The flow is c.arac.erized by three parameters： /3 the ratio of radius to length of the arterial segment, Re the c.arac.eristic.Reynolds number assoc.ated with the pressure outside the arterial segment and c.the filtration c.e^c.ent. The problem has been solved by the use of a perturbation tec.nique, e is c.nsidered to be very small, ensuring the validity of the perturbation method. The c.mputed numeric.l results are presented graphic.lly to depic. the variations in veloc.ty, volumetric.flow rate, wall shear stress and flow resistanc..

关键词： Slip veloc.ty permeable artery newtonian fluid.

Symplec.ic.feedbac. using Hamiltonian Lie algebra and its applic.tions to an inverted pendulum

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

控制理论与应用（英文版） 2013年第2期11卷 275-281页

作者： j. Lorc. eSPIRO c. Munoz POBLeTe Departamento de c.enc.as Fisic.s Facultad de Ingenieria Ciencias y Administracion Universidad de La FronteraAvenida Francisco Salazar 01145 Casilla 54-D Temuco Chile Departamento de Ingenieria elec.ric. Facultad de Ingenieria Ciencias y Administracion Universidad de La FronteraAvenida Francisco Salazar 01145 Casilla 54-D Temuco Chile

From the symplec.ic.representation of an autonomous nonlinear dynamic.l system with holonomic.c.n- straints, i.e., those that c.n be represented through a symplec.ic.form derived from a Hamiltonian, we present a new proof on the realization of the symplec.ic.feedbac. ac.ion, whic. has several theoretic.l advantages in demonstrating the uniqueness and existenc. of this type of solution. Also, we propose a tec.nique based on the interpretation, c.nstruc.ion and c.arac.er- ization of the pull-bac. differential on the symplec.ic.manifold as a member of a one-parameter Lie group. This allows one to synthesize the c.ntrol law that governs a c.rtain system to ac.ieve a desired behavior; and the method developed from this is applied to a c.assic.l system suc. as the inverted pendulum.

关键词： Hamiltonian systems Symplec.ic.struc.ures Lie algebra Nonlinear dynamic.l systems Geometric.c.n-trol