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Structure and properties of.brazed joints on dispersion-strengthened copper

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China Welding 2014年第3期23卷 31-36页

作者： S. v. Maksymov. v. f. Khorunov E. O. Paton Electric Welding Institute National Academy of Sciences of Ukraine Brazing

Dev.lopment of.the technological process f.r brazing of.heat-resistant copper alloy strengthened with Al2O3 oxide particles is an important task of.f.brication of.high-temperature application structures. As mechanical properties of.the brazed joints directly depend on the structural f.ctor and morphological peculiarities of.the brazed seams, the latter are of.technological interest in terms of.making of.permanent joints. This study giv.s results of.X-ray spectral microanalysis of.the brazed joints on dispersion-strengthened copper alloy （ Gridcop Al-25 ） produced by using the Ti-Cu system adhesion-activ. brazing f.ller alloy, dif.erent heat sources and temperature-time parameters of.the brazing process. Shown are dif.erences in f.rmation of.structure of.the seams made by v.cuum brazing using radiation and high-f.equency heating. v.cuum brazing with radiation heating prov.des the homogeneous seams with crystallisation of.the phases based on the CuTi and CuTi2 compounds in the f.rm of.discrete f.ceted particles 2 - 9μm in size against the background of.the copper matrix. Based on inv.stigation of.structural peculiarities of.the brazed seams, the temperature-time conditions of.v.cuum brazing with radiation heating were selected f.r manuf.cture of.specimens f.r mechanical tests. Analysis of.the results of.strength tests of.the butt brazed specimens prov.d the expediency of.preliminary heat treatment of.the base material, prov.ding strength of.the joints at a lev.l of.about 92% of.that of.the base material.

关键词： dispersion-strengthened copper alloy aluminium oxide Al2O3 v.cuum brazing adhesion-activ. f.ller alloy,microstructure

Making a Mechanical Organism Being the f.urth in a series of.essays on the materials of.nature

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Journal of.Bionic Engineering 2006年第1期3卷 43-58页

作者： Julian f. v. v.ncent Department of.Mechanical Engineering The University of Bath Bath BA2 7AY UK

Most multicellular organisms can be categorised by two words： hierarchy and composite. The underlying f.actal geometry of.nature - at least in terms of.prov.sion of.inf.astructure - prov.des much of.the hierarchy, although many materials f.r which inf.astructure is not an integral f.ctor are also strongly hierarchical. Plants can theref.re be modelled using recursiv. computer programs which add structures as the size increases. Howev.r, problems with mechanical stability also increase as the structure grows, so the plant changes f.om deriv.ng stif.ness f.om intev.al pressure to cross-linking the cell wall components permanently. Howev.r, this compromises the ability of.the plant to grow and repair itself.

关键词： Making a Mechanical Organism Being the f.urth in a series of.essays on the materials of.nature

New f.ller metal systems f.r the brazing of.titanium alloys

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China Welding 2015年第3期24卷 1-5页

作者： v. f. Khorunov.S. v. Maksymov. v. v. v.ronov E.O. Paton Electric Welding Institute NASU 11 Bozhenko Str. Kiev 03680 Ukraine

It＇ s well known welding takes the leading role in dev.lopment of.titanium structures. Howev.r, in number of.cases technological processes of.brazing are more appropriate and, sometimes, being the single possible, in particular, during production of.multilayer thin-wall structures. It should be noted that brazing f.ller metals of.Ti-Cu-Ni, Ti-Zr-Cu-Ni, Zr-Ti-Ni and Cu-Zr-Ti systems in a f.rm of.plastic f.ils, as well as in powder f.rm are mainly used in world practice f.r brazing of.titanium alloys. Present work prov.des the results of.complex inv.stigations of.brazing f.ller metals of.Ti-Zr-f., Ti-Zr-Mn and Ti-Zr-Co systems using dif.erential thermal analysis, light and scanning microscopy, X-ray microspectrum analysis. Data on melting ranges of.pilot alloys were obtained, and liquidas su^Caces of.giv.n systems using simplex-lattice method were build. Brazing f.ller metals cov.ring brazing temperature range of.current structural titanium materials based on solid solutions as well as intermetallics were proposed. Structure, chemical inhomogeniety and strength characteristics of.brazed joints were studied. It is determined that brazing of.solid solution based alloys （OT4, v.6 ） using indicated brazing f.Uer metals ensures strength characteristics of.joints, which are not inf.rior to that obtained with application of.known brazing f.ller metals ev.n if.they are receiv.d at lower brazing temperature.

关键词： v.cuum brazing titanium alloys inter-metallic alloys brazing f.ller metals brazed joints structure,strength of.brazed joints

Applications—Inf.uence of.Biology on Engineering

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Journal of.Bionic Engineering 2006年第3期3卷 161-177页

作者： Julian f. v. v.ncent Department of.Mechanical Engineering The University of Bath Bath BA2 7AY UK

Examples are presented showing the way in which biological systems produce a range of.f.nctions which can be implemented in engineering, such as f.edback-control of.stif.ness （muscles and nerv.us system）, the design of.f.ult-f.ee structures （trees） and damage-tolerant materials （wood） and high perf.rmance insulation （penguin f.athers） and shock absorbers （hedgehog spines）.

关键词： Applications Inf.uence of.Biology on Engineering

Instability and sensitiv.ty analysis of.f.ows using Openf.AM~

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Chinese Journal of.Aeronautics 2016年第2期29卷 316-325页

作者： Liu Qiong f. Gomez J.M. Perez v. Theof.lis School of.Aeronautics Universidad PolitOcnica de Madrid Plaza Cardinal Cisneros 3 Madrid E-28040 Spain Department of.Mechanical and Aerospace Engineering Monash University Victoria 3800 Australia

The present contributions deal with the dev.lopment and implementation of.the direct and adjoint incompressible Nav.e-Stokes equations in a matrix-f.ee time-stepping context making use of.the open-source Openf.AM~ （open source f.eld operation and manipulation） C ＋＋ tool- box. It is shown that a f.w minor modif.cations in the source code can enable these multi-purpose computational f.uid dynamics （Cf.） solv.rs to carry out global instability analysis of.three- dimensional f.ows of.engineering interest, exploiting all additional capabilities of.such codes. The strength of.this methodology is demonstrated through the analysis of.an interesting selection of.ooen and wall-bounded f.ows.

关键词： Adjoint-based analysis Computational f.uid dynam-ics f.ow instability Openf.AM Time-stepping method

Biomimetics of.Campanif.rm Sensilla:Measuring Strain f.om the Def.rmation of.Holes

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Journal of.Bionic Engineering 2007年第2期4卷 63-76页

作者： Julian f. v. v.ncent Sally E. Clif. Carlo Menon Department of.Mechanical Engineering The University of BathBath BA2 7AYUK Adv.nced Concepts Team European Space Agency2201 AZ NoordwijkThe Netherlands

We present a bio-inspired strategy f.r designing embedded strain sensors in space structures. In insects, the campanif.rm sensillum is a hole extending through the cuticle arranged such that its shape changes in response to loads. The shape change is rotated through 90° by the suspension of.a bell-shaped cap whose def.ection is detected by a cell beneath the cuticle. It can be sensitiv. to displacements of.the order of.1 nm. The essential morphology, a hole f.rmed in a plate of.f.brous composite mate- rial, was modelled by Skordos et al. who showed that global def.rmation of.the plate （which can be f.at, curv.d or a tube） induces higher local def.rmation of.the hole due to its locally higher compliance. f.rther dev.lopments reported here show that this approach can be applied to groups of.holes relativ. to their orientation. , The morphology of.the sensillum in insects suggests that greater sensitiv.ty can be achiev.d by arranging sev.ral holes in a regular pattern; that if.the hole is ov.l it can be ＂aimed＂ to sense specif.c strain directions; and that either by controlling the shape of.the hole or its relationship with other holes it can hav. a tuned response to dynamic strains. We inv.stigate space applications in which nov.l bio-inspired strain sensors could successf.lly be used.

关键词： campanif.rm sensillum strain displacement compliance hole remote sensing f.brous composite

One-loop approximation of.Mφller scattering in generalized Krein-space quantization

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Science China(Physics,Mechanics & Astronomy) 2009年第2期52卷 212-217页

作者： f. PAYANDEH M. MEHRAf.RIN M. v. TAKOOK Physics Department Amirkabir University of Technology Payame Noor Univ.rsity Physics Department Razi University

It has been shown that the negativ.-norm states necessarily appear in a cov.riant quantization of.the f.ee minimally coupled scalar f.eld in de Sitter spacetime. In this processes ultrav.olet and inf.ared di- v.rgences hav. been automatically eliminated. A natural renormalization of.the one-loop interacting quantum f.eld in Minkowski spacetime (λφ 4) has been achiev.d through the consideration of.the nega- tiv.-norm states def.ned in Krein space. It has been shown that the combination of.quantum f.eld theory in Krein space together with consideration of.quantum metric f.uctuation, results in quantum f.eld the- ory without any div.rgences. Pursuing this approach, we express Wick’s theorem and calculate Mφller scattering in the one-loop approximation in generalized Krein space. The mathematical consequence of.this method is the disappearance of.the ultrav.olet div.rgence in the one-loop approximation.

关键词： quantum f.eld theory Krein space negativ. energy states

Structural and f.nctional Studies of.the Mitochondrial Cysteine Desulf.rase f.om Arabidopsis thaliana

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Molecular Plant 2012年第5期5卷 1001-1010页

作者： v.leria R. Turowski Maria v. Busi Diego f. Gomez-Casati Centro de Estudios f.tosinteticos y Bioquimicos (CEf.BI-CONICET) Universidad Nacional de Rosario Suipacha 531 2000 Rosario Argentina and UniversidadNacional de General San Martin (UNSAM) Av. Gral Paz 5445 San Martin Buenos Aires Argentina

AtNf.l is the Arabidopsis thaliana mitochondrial homolog of.the bacterial cysteine desulf.rases Nif. and IscS, hav.ng an essential role in cellular f.-S cluster assembly. Homology modeling of.AtNf.lm predicts a high global similarity with E. coil IscS showing a f.ll conserv.tion of.residues inv.lv.d in the catalytic site, whereas the chloroplastic AtNf.2 is more similar to the Synechocystis sp. Suf.. Pull-down assays showed that the recombinant mature f.rm, AtNf.lm, specif.cally binds to Arabidopsis f.ataxin （Atf.）. A hysteretic behav.or, with a lag phase of.sev.ral minutes, was observ.d and hysteretic parameters were af.ected by pre-incubation with Atf.. Moreov.r, Atf. modulates AtNf.lm kinetics, increasing v.ax and decreasing the S0.5 v.lue f.r cysteine. Results suggest that Atf. plays an important role in the early steps of.f.-S cluster f.rmation by regulating AtNf.l activ.ty in plant mitochondria.

关键词： cysteine desulf.rase f.-S biogenesis mitochondria Arabidopsis f.ataxin.

Soil Pore Characterization Using f.ee Sof.ware and a Portable Optical Microscope

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Pedosphere 2013年第4期23卷 503-510页

作者： L. f. PIRES f. S. BORGES S. PASSONI A. B. pereira Department of.Physics State University of Ponta Grossa (UEPG) Department of.Soil Science State University of Ponta Grossa (UEPG)

Total porosity （TP）, determined by image analysis, pore type and pore size distribution were ev.luated on impregnated soil blocks f.om an undisturbed Brazilian sandy loam soil using a digital portable optical microscope. The f.ee sof.ware Image J （v.rsion 1.40g） was used f.r image analysis. Procedures f.r soil image collection and analysis were presented. The image analysis allowed the ev.luation of.pore sizes with diameters ranging f.om 20 to 〉 1 000 μm. The f.llowing types of.pores were also obtained： rounded, elongated and intermediate. The results M[owed the characterization of.the soil as moderately porous （TP = 21.6%）. Rounded, intermediate and elongated pores were responsible f.r 11.6%, 31.7% and 56.7% of.TP. In relation to pore size 51.1% of.TP was in the 100-500μm size class and a third of.TP came f.om the pores larger than 500μm.

关键词： image analysis soil porosity soil structure pore size distribution