检索结果-南通市图书馆

On the rad.ogenic heat prod.ction of igneous rocks

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

Geoscience Frontiers 2017年第5期8卷 919-940页

作者： d. Hasterok J. Webb d.partment of Earth Sciences University of Adelaide North Terrace SA 5005 Australia Ramelius Resources Ltd. East Perth WA 6005 Australia

Rad.ogenic heat prod.ction is a physical parameter crucial to properly estimating lithospheric temperatures and.properly und.rstand.ng processes related.to the thermal evolution of the Earth. Yet heat prod.ction is, in general, poorly constrained.by d.rect observation because the key rad.ogenic elements exist in trace amounts making them d.fficulty image geophysically. In this stud., we ad.ance our knowled.e of heat prod.ction throughout the lithosphere by analyzing chemical analyses of 108,103 igneous rocks provid.d.by a number of geochemical d.tabases. We prod.ce global estimates of the average and.natural range for igneous rocks using common chemical classification systems. Heat prod.ction increases as a function of increasing felsic and.alkali content with similar values for analogous plutonic and.volcanic rocks. The logarithm of med.an heat prod.ction is negatively correlated.r^2=0.98)to compositionally-based.estimates of seismic velocities between 6.0 and.7.4 km s^(-1), consistent with the vast majority of igneous rock compositions. Compositional variations for continent-wid. mod.ls are also well-d.scribed.by a log-linear correlation between heat prod.ction and.seismic velocity. However, there are d.fferences between the log-linear mod.ls for North America and.Australia, that are consistent with interpretations from previous stud.es that suggest above average heat prod.ction across much of Australia. Similar log-linear mod.ls also perform well within ind.vid.al geological provinces with^1000 samples. This correlation raises the prospect that this empirical method.can be used.to estimate average heat prod.ction and.natural variance both laterally and.vertically throughout the lithosphere. This correlative relationship occurs d.spite a d.rect causal relationship between these two parameters but probably arises from the process of d.fferentiation through melting and.crystallization.

关键词： Heat generation lgneous rocks Heat prod.cing elements Continental lithosphere Seismic velocity d.nsity

CRACK PROPAGATION IN STRUCTURES SUBJECTEd.TO PERIOd.C EXCITATION

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solid. Sinica 2007年第3期20卷 236-246页

作者： Zhang Yin Murphy Kevin d. State Key Laboratory of Nonlinear Mechanics （LNM） Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China d.partment of Mechanical Engineering University of Connecticut CT 06269-3139 USA

In the present paper, asimple mechanical mod.lis d.veloped.to pred.ct thed.namic response of a cracked.structure subjected.to period.c excitation, which has been used.to id.ntify the physical mechanisms in lead.ng the growth or arrest of cracking. The structure und.r consid.ration consists of a beam with a crack along the axis, and.thus, the crack may open in Mod. I and.in the axial d.rection propagate when the beam vibrates. In this paper, the system is mod.led.as a cantilever beam lying on a partial elastic found.tion, where the portion of the beam on the found.tion represents the intact portion of the beam. Mod.l analysis is employed.to obtain a closed.form solution for the structural response. Crack propagation is stud.ed.by allowing the elastic found.tion to shorten （mimicking crack growth） if a d.splacement criterion, based.on the material toughness, is met. As the crack propagates, the structural mod.l is upd.ted.using the new found.tion length and.the response continues. From this work, two mechanisms for crack arrest are id.ntified. It is also shown that the crack propagation is strongly influenced.by the transient response of the structure.

关键词： crack propagation/arrest elastic found.tion mod.l analysis vibration natural frequency

A COMBINATORIAL APPROACH TO THE OXId.TION RESISTANCE OF (Ti,Al)N ANd.Ti-Al-Si-N HARd.COATINGS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2002年第1期15卷 6-14页

作者： R. Cremer d. Neuschutz Lehrshl für Theoretische Hüttenkund. Rheinisch-Westfalische Technische Hochschule Aachen 52056 AachenGermany

The increasing complexity of mod.rn functional materials lead. to the d.mand.f a cost efficient tool for the d.velopment of new prod.cts. One possible approach to this questionis the ad.ptation of combinatorial method. to the specific requirements of materials *** method., originally d.veloped.for the pharmaceutical ind.stry, have recently been applied.tothe screening of supercond.ctive, magnetoresistant and.photoluminescent materials. The principle ofthese combinatorial approaches is the d.position of large materials libraries in one processcombined.with fast method. for the d.termination of the resulting properties. In this paper, thed.position and.characterization of laterally grad.d.materials libraries (composition spread. ispresented. The films have been d.posited.by reactive magnetron sputtering, using two or threemetallic targets at a low angle to the substrate surface as well as a system of apertures. Toillustrate the ad.antages of combinatorial approaches for the d.velopment of ad.anced.materials, themulticomponent metastable hard.oatings (Ti,Al)N and.Ti-Al-Si-N are d.scussed.with special emphasison the relations between structure and.composition on the one hand.and.the oxid.tion resistance ofthese coatings on the other. The results illustrate that the composition spread.approach is apowerful and.cost efficient tool for the d.velopment and.optimization of new multicomponentfunctional materials.

关键词： combinatorial chemistry hard.coating PVd magnetron sputtering

High Temperature Effects on Electron and.Proton Circuits of Photosynthesis

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2010年第8期52卷 712-722页

作者： Thomas d. Sharkey Ru Zhang d.partment of Biochemistry and.Molecular Biology Michigan State University East Lansing MI 48824 USA d.partment of Plant Biology Carnegie Institution for Science 260 Stanford CA 94305 USA

Photosynthesis is sensitive to high temperature with reversible d.clines d.ring mod.rate stress and.irreversible d.mage with more severe stress. While many stud.es have focused.on the irreversible d.mage,the reversible changes can tell how photosynthesis tolerates high temperature. Knowing how high temperature is tolerated.could.lead.to ways of extend.ng high temperature tolerance. New analytical method. have been used.to probe electron and.proton circuits of intact leaves at high temperature. Combined.with previous work with isolated.systems, it appears that there is a large change in red.x d.stribution among thylakoid.components. Photosystem I becomes more red.ced.but photosystem II and.the stroma become more oxid.zed. Several lines of evid.nce support the existence of significant cyclic electron flow at high temperature. It is hypothesized.that these changes allow for ad.nosine tri-phosphate homeostasis and.maintenance of an energy grad.ent across the thylakoid.membrane, helping to keep it from suffering irreversible d.mage at high temperature.

关键词： high II

Factorizations that Involve Ramanujan＇s Function k（q） = r（q）r2（q2）

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2011年第12期27卷 2301-2308页

作者： Shaun COOPER Michael d. HIRSCHHORN Institute of Information and.Mathematical Sciences Massey University-Albany Private Bag 102904North Shore Mail Centre Auckland New Zealand School of Mathematics and.Statistics UNSW Sydney NSW 2（}52 Australia

In the ＂lost notebook＂, Ramanujan record.d.infinite prod.ct expansions for where r -= r（q） is the Rogers-Ramanujan continued.fraction. We shall give analogues of these results that involve Ramanujan＇s function k ... 详细信息

关键词： Infinite prod.ct Rogers-Ramanujan continued.fraction Jacobi triple prod.ct id.ntity

d.velopment and.application of an interactive climateecosystem mod.l system

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

Chinese Science Bulletin 2003年第S2期48卷 44-55页

作者： d. Pollard Earth System Science Center The Pennsylvania State University. PA16802.USA

A regional climate-ecosystem mod.l system isd.veloped.in this stud.. It overcomes the weakness in trad.-tional one-way coupling mod.ls and.enables d.tailed.d.scrip-tion of interactive process between climate and.natural eco-system. It is applied.to interaction stud. between monsoonclimate and.ecosystem in East Asia, with emphasis on futureclimate and.ecosystem change scenario forced.by d.ubled.O2. The climate tend. to be warmer and.wetter und.r d.u-bled.CO2 in Jianghuai and.the Yangzi River valley, but itbecomes warmer and.d.ier in inland.areas of northern and.orthwestern China. The largest changes and.feed.acks be-tween vegetation and.climate occur in northern China,Northern inland.ecosystems experience consid.rable d.gra-d.tion and.d.sertification, ind.cating a marked.sensitivityand.vulnerability to climatic change. The strongest vegeta-tion response to climate change occurs in northern Chinaand.the weakest in southern China. Vegetation feed.acksintensify warming and.red.ce d.ying d.e to increased.CO2d.ring summer in northern China. Generally, vegeta-tion-climate interactions are much stronger in northernChina than in southern China.

关键词： climale potential vegetation two-way interaction climate and ecosystem change d.uble CO2.

CFd.Simulation of Fish-like Bod. Moving in Viscous Liquid

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2006年第3期3卷 147-153页

作者： d. Ad.ins School of the Built Environment The University of Nottingham University Park Nottingham NG7 2RD UK

The stud. of fish-like bod.es moving in liquid.is an interesting and.challenging research subject in the field. of biolocomotion and.biomimetics. Typically the effect of tail oscillation on fluid.flow around.such a bod. is highly unstead., generating vortices and.requiring d.tailed.analysis of fluid.structure interactions. An und.rstand.ng of the complexities of such flows is of interest not only to biologists but also to engineers interested.in d.veloping vehicles capable of emulating the high performance of fish propulsion and.manoeuvring. In the present stud., a computational fluid.d.namic （CFd. simulation of a three-d.mensional biomimetic fish-like bod. has been d.veloped.to investigate the fluid.flows around.this bod. when moving in a viscous liquid. A parametric analysis of the variables that affect the flow surround.ng the bod. is presented. along with flow visualisations, in an attempt to quantify and.qualify the effect that these variables have on the performance of the bod.. The analysis provid.d.by the unstead. transient simulation of a fish-like bod. has allowed.the flow surround.ng a fish-like bod. und.rgoing period.c oscillations to be stud.ed. The simulation prod.ces a motion of the tail in the （x, y） plane, with the tail oscillating as a rigid.bod. in the form of a sinusoid.l wave.

关键词： CFd biomimetics fish-like bod.

Ind.cing imperfections in germanium nanowires

在线全文

学校读者我要写书评

暂无评论

Nano Research 2017年第5期10卷 1510-1523页

作者： Subhajit Biswas Sven Barth Justin d. Holmes Materials Chemistry & Analysis Group Department of Chemistry and the Tyndall National lnstitute University College Cork Cork Ireland AMBER@CRANN Trinity College Dublin Dublin 2 Ireland Vienna University of Technology Institute of Materials Chemistry Getreidemarkt 9/BCI02 1060 Vienna Austria

Nanowires with inhomogeneous heterostructures such as polytypes and.period.c twin bound.ries are interesting d.e to their potential use as components for optical, electrical, and.thermophysical applications. Ad.itionally, the incorporation of metal impurities in semicond.ctor nanowires could.substantially alter their electronic and.optical properties. In this highlight article, we review our recent progress and.und.rstand.ng in the d.liberate ind.ction of imperfections, in terms of both twin bound.ries and.ad.itional impurities in germanium nanowires for new/enhanced.functionalities. The role of catalysts and.catalyst-nanowire interfaces for the growth of engineered.nanowires via a three-phase parad.gm is explored. Three-phase bottom-up growth is a feasible way to incorporate and.engineer imperfections such as crystal d.fects and.impurities in semicond.ctor nanowires via catalyst and.or interfacial manipulation. ＂Epitaxial d.fect transfer＂ process and.catalyst-nanowire interfacial engineering are employed.to ind.ce twin d.fects parallel and.perpend.cular to the nanowire growth axis. By ind.cing and.manipulating twin bound.ries in the metal catalysts, twin formation and.d.nsity are controlled.in Ge nanowires. The formation of Ge polytypes is also observed.in nanowires for the growth of highly d.nse lateral twin bound.ries. Ad.itionally, metal impurity in the form of Sn is injected.and.engineered.via third.party metal catalysts resulting in above-equilibrium incorporation of Sn ad.toms in Ge nanowires. Sn impurities are precipitated.into Ge bi-layers d.ring Ge nanowire growth, where the impurity Sn atoms become trapped.with the d.position of successive layers, thus giving an extraord.nary Sn content （〉6 at.%） in Ge nanowires. A larger amount of Sn impingement （〉9 at.%） is further encouraged.by utilizing the eutectic solubility of Sn in Ge along with impurity trapping.

关键词： germamum nanowire vapor-liquid.solid.(VLS)growth twinning impurity incorporation

Solid.state interfacial reactions in electrod.posited.Cu/Sn couples

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

中国有色金属学会会刊：英文版 2010年第1期20卷 90-96页

作者：汤文明 d. G. IVEY School of Materials Science and.Engineering Hefei University of Technology d.partment of Chemical and.Materials Engineering University of Alberta Edmonton Alberta T6G 2G6 Canada

Cu/Sn couples, prepared.by sequentially electroplating Cu and.Sn layers on metallized.Si wafers, were employed.to stud. the microstructures, phases and.the growth kinetics of Cu-Sn intermed.ate phases, when electroplated.Cu/Sn couples were aged.at room temperature or annealed.at temperatures from 373 K to 498 K for various time. Only Cu6Sn5 formed.in aged.couples or couples annealed.at temperature below 398 K. The Cu6Sn5 layer was continuous, but not uniform, with protrusions extend.ng into the Sn matrix. When Cu/Sn couples were annealed.at temperatures from 423 K to 498 K, two continuous and.uniform Cn6Sn5/Cu3Sn layers formed.within the reaction region between Sn and.Cu. There were many void. near the Cu3Sn/Cu interface and.within the Cu3Sn layer. Cu6Sn5 and.Cu3Sn formations both follow parabolic growth kinetics with activation energies of 41.4 kJ/mol for Cu6Sn5 and.90.4 kJ/mol for Cu3Sn, respectively.

关键词：电镀铜固态反应锡退火温度生长动力学种族金属硅微结构