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| 1 | Macroscopic relationship for preferential flow in the vadose zone:Theory and validation显示文摘Preferential flow commonly observed in unsaturated soils allows rapid movement of solute from the ground surface or vadose zone to the groundwater, bypassing a significant volume of unsaturated soil and increasing the risk of groundwater contamination. A variety of evidence indicates that complex preferential flow patterns observed from fields are fractals. This paper discusses a macroscopic relationship for modeling preferential flow in the vadose zone. Conceptually, the flow domain can be divided into active and inactive regions. Flow occurs preferentially in the active region (characterized by fractals), and inactive region is simply bypassed. The portion of the active region was found to be a power function of saturation. The validity of this macroscopic relationship is demonstrated by its consistency with field observations and the related numerical experiments. | LIU HuiHai1 & ZHANG RenDuo2 1 Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 947200, USA 2 School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China | 2009 | Science China(Technological Sciences)2009，52，11： | 5 |
| 2 | CONTROLLING HIGHTEMPERATURE DEFORMATION BY VARYING MICROSTRUCTURE IN A Ti47Al2Cr2Nb ALLOY显示文摘A Ti 47Al 2Cr 2Nb alloy was made by powder extrusion methods. By varying extrusion temperature, different microstructures were produced. At an extrusion temperature of 1 400 ℃ (above α transus), a uniform, fully lamellar structure was observed. In contrast, when powders were extruded at 1 150 ℃, an inhomogeneous microstructure consisting of γ,α 2 and metastable β phases was obtained. It was demonstrated that, while alloy extruded at 1 400 ℃ exhibited an excellent creep resistance, alloy with the same composition extruded at 1 150 ℃ exhibited superplasticity. The good creep resistance was resulted from the presence of fine lamellae which restrict dislocation slip within γ grains. These fine lamellae also promote the nucleation of deformation twins which impede dislocation glide along the interfaces ( γ/γ and γ/α 2) and, thus, reduces creep rate. In the case of low temperature extrusion, an elongation value of over 300% was obtained at a strain rate of 2×10 -5 s -1 and at a temperature as low as 800 ℃, which is close to the ductile to brittle transition temperature. This is in contrast to the prior major observations of superplastic behaviors in TiAl in which typical temperatures of 1 000 ℃ have usually been required for superplasticity. It was proposed that the occurrence of superplasticity at 800 ℃ is caused by the presence of a B2 phase which, during superplastic deformation (grain boundary sliding), accommodates sliding strains to reduce the propensity for cavitation at grain triple junctions and, thus, delays the fracture process. | T.G.Nieh and J.Wadsworth Lawrence Livermore National Laboratory, L-369, P.O.Box 808, Livermore, CA 94550, U.S.A. | 1999 | 中国有色金属学会会刊:英文版1999，9，S1： | 5 |
| 3 | EFFECTS OF ALLOYING ELEMENTS ON CREEP OF TiAl ALLOYS WITH FINELAMELLAR STRUCTURES显示文摘Creep experiments have been conducted on five powder metallurgy TiAl alloys with fine grains (65~80 μm), fine lamellar spacings (0.1~0.16 μm), and different compositions [Ti 47Al(+Cr, Nb, Ta, W, Si)] at temperatures of 760 ℃ and 815 ℃ and stresses from 35 to 723 MPa. Results show that at a given lamellar spacing 1% Nb(mole fraction) with 1% Ta and replacing 0.2% Ta with 0.2% W induced little effect, but addition of 0.3% Si decreased the creep resistance by a factor of 3~4 under otherwise identical conditions. These different effects of different alloying elements are interpreted in terms of the interaction of alloy segregants with misfit and/or misorientaion dislocations at the lamellar interface. That is, the interaction retards or facilitates the climb of interfacial dislocations, which is rate controlling during creep, depending on the size of the segregants relative to the host atoms. | J.N.Wang, B.Y.Huang and T.G.Nieh National Key Laboratory for Powder Metallurgy, Central South University of Technology, Changsha 410083, China Lawrence Livermore National Laboratory, P.O.Box 808, Livermore, CA 94550, U.S.A. | 1999 | 中国有色金属学会会刊:英文版1999，9，S1： | 2 |
| 4 | Recent Advances in Superplastic Intermetallics显示文摘RecentAdvancesinSuperplasticIntermetallicsNIEHTai-Gang;WADSWORTHJeffrey(LawrenceLivermoreNationalLaboratory,Livermore,CA94550... | NIEH Tai-Gang WADSWORTH Jeffrey (Lawrence Livermore National Laboratory, Livermore, CA 94550, USA) | 1995 | Acta Metallurgica Sinica(English Letters)1995，8，Z1： | 2 |
| 5 | An Overview of Tissue Engineered Bone显示文摘 | Vacanti CA Bonassar Lawrence J | 1999 | Clinical Orthopaedics & Related Research1999，367，： | 1 |
| 6 | Halo eczema-resolution after excision of the central naevus alone显示文摘 | Cox NH Bloxham CA Lawrence CM | 1991 | Clin Exp Dermatol1991，16，1： | 1 |
| 7 | The clinical research nurse显示文摘 | Mccabe M Cahil Lawrence CA | 2007 | Am J Nurs2007，107，9： | 1 |
| 8 | Sedimentation velocity analysis of flexible macromolecules:self-association and tangling of amyloid fibrils显示文摘 | MacRaild CA Hatters DM Lawrence LJ | 2003 | Biophys J2003，84，4： | 1 |
| 9 | THE CHANGING ROLE OF THE NATIONAL LABORATORIES IN MATERIALS RESEARCH显示文摘THECHANGINGROLEOFTHENATIONALLABORATORIESINMATERIALSRESEARCHWADSWORTHJeffreyandFLUSSMichael(ChemistryandMaterialsScienceDirect... | WADSWORTH Jeffrey and FLUSS Michael(Chemistry and Materials Science Directorate,Lawrence Livermore National Laboratory, Livermore, CA 94551) | 1995 | Acta Metallurgica Sinica(English Letters)1995，8，Z1： | 1 |
| 10 | Halo eczema-resolution after excision of the central naevus alone显示文摘 | Cox NH Bloxham CA Lawrence CM | 1991 | Clin Exp Dermatol1991，16，1： | 1 |
| 11 | ERPs and the evoked cardiac re- sponse to auditory stimuli: Intensity and cognitive load effects 显示文摘 | Lawrence CA Barry RJ | 2009 | Acta Neurobiol Exp2009，69，4： | 1 |
| 12 | DNA covalent immobi- lization onto screen-printed electrode networks for direct label- free hybridization detection of p53 sequences 显示文摘 | Marquette CA Lawrence MF Blum KI | 2006 | Anal Chem2006，78，3： | 1 |
| 13 | 1 显示文摘 | Stevens RV Gaetaf CA Lawrence DS Camphorae: chiral intermediates for the enantiospecific total synthesis of steroids | 1983 | JAm Chem Soc1983，105，26： | 1 |
| 14 | Outcome of revision hip arthroplasty done without cement显示文摘 | Lawrence JM Engh CA Macalino GE | 1994 | J Bone Joint Sury Am1994，76，7： | 1 |
| 15 | Radiological use of high energy deuterons and alpha particles显示文摘 | Tobias CA Anger HO Lawrence JH | 1952 | Am J Roetgenol1952，67，： | 1 |
| 16 | A network biology approach to prostate cancer 显示文摘 | Ergun A Lawrence CA Kohanski MA | 2007 | Mol Syst Biol2007，3，： | 1 |
| 17 | The clinical research nurse显示文摘 | McCabe M Cahill Lawrence CA | 2007 | Am J Nurs2007，107，9： | 1 |
| 18 | Methylphenidate effects in attention deficit/hyperactivity disorder:Electrodermal and ERP measures during a continuous performance task显示文摘 | Lawrence CA Barry RJ Clarke AR | 2005 | Psychopharnmacology (Berl)2005，183，1： | 1 |
| 19 | Intracellular distribution of histone mRNAs in human fibroblasts studied by in situ hybridization显示文摘 | LAWRENCE JB SINGER RH VILLNAVE CA etal | 1988 | Proc Natl Acad Sci USA1988，85，2： | 1 |
| 20 | Human breast milk: Current concepts ofimmunology and infectious diseases 显示文摘 | Lawrence RM Pane CA | 2007 | Curr Probl PediatrAdolesc HeahhCare2007，37，： | 1 |
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