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B. Schönfelder G. Gottstein L. S. Shvindlerman 《Metallurgical and Materials Transactions A》2006,37(6):1757-1771
While the motion of twist boundaries can be readily studied by atomistic simulations with molecular dynamics (MD) under the
action of an elastic driving force, the approach fails for tilt boundaries. This is due to the interaction of the elastic
stress with the grain boundary (GB) structure, which causes plastic strain by GB sliding. A novel concept, the orientation
correlated driving force, is introduced to circumvent this problem. It is shown that this concept can be successfully applied
to the study of the migration of tilt boundaries. The migration behavior of several twist and tilt GBs was investigated. The
transition from low-to high-angle boundaries can be captured, and a structural transition of tilt boundaries was found at
high temperatures, which also affected the migration behavior. The results compare well with experimental results of the motion
high-angle boundaries, but for low-angle boundaries, the agreement is poor.
This article is based on a presentation made in the “Hillert Symposium on Thermodynamics & Kinetics of Migrating Interfaces
in Steels and Other Complex Alloys,” December 2–3, 2004, organized by The Royal Institute of Technology in Stockholm, Sweden. 相似文献
5.
S. Büttgenbach J. Hesselbach R. Tutsch M. Berndt B. Hoxhold K. Schöttler 《Microsystem Technologies》2006,12(7):665-669
Positioning accuracies in the range of a few micrometers and below are necessary for the assembly of active micro-systems. In order to reach these accuracies, an assembly system for sensor guided micro-assembly is developed in the Collaborative Research Centre 516 “Design and manufacturing of active micro-systems”. The combination of a parallel robot with an integrated 3D vision sensor and a micro-gripper enables to reach relative positioning accuracies below 1 μm. 相似文献
6.
A modified natural surfactant was administered to a patient with life-threatening adult respiratory distress syndrome caused by viral pneumonia. Subsequently, there was a marked improvement in gas exchange. In order to assess the mechanism for improved oxygenation, computed tomography of the lungs was done. Quantitative analysis of the scans taken before and after surfactant administration indicates that improvement in gas exchange was largely due to the expansion of underinflated and collapsed lung areas. Although this is a single case report, it provides insight into the possible beneficial effect of instilled surfactant in severe respiratory distress from viral pneumonia. 相似文献
7.
A micromechanics analysis is performed for the determination of the five independent elastic moduli of unidirectional fiber composites. By considering viscoelastic phases and by using the correspondence principle and the inversion of the Laplace transform, the five time-dependent functions which characterize the effective behavior of viscoelastic composites are established. The predicted time-dependent behavior is applied for the analysis of viscoelastic laminated plates. The resulting viscoelastic effects are shown, and comparison between the results obtained within the classical laminated plate theory and the first-order shear deformation theory is discussed. 相似文献
9.
Jacob Hooker David Hinks Gerardo Montero Christopher Conlee 《Coloration Technology》2002,118(6):273-276
The synthesis of azo dyes via a conventional aqueous-based diazotisation and coupling reaction requires the use of relatively high concentrations of mineral acids, which leads to high electrolyte concentrations in wastewater. Reported in this paper is an environmentally benign one-pot method for the synthesis of a nonionic azo dye, N,N -diethyl- N -{4-[( E )-(4-nitrophenyl)diazenyl]phenyl}amine, in supercritical carbon dioxide without using a mineral acid. The product yield increased significantly with temperature, with 91% theoretical yield afforded at 80 °C. The pressure of the system had little influence on product yield. 相似文献
10.
Gibbs energies of formation of CoF2 and MnF2 have been measured in the temperature range from 700 to 1100 K using Al2O3-dispersed CaF2 solid electrolyte and Ni+NiF2 as the reference electrode. The dispersed solid electrolyte has higher conductivity than pure CaF2 thus permitting accurate measurements at lower temperatures. However, to prevent reaction between Al2O3 in the solid electrolyte and NiF2 (or CoF2) at the electrode, the dispersed solid electrolyte was coated with pure CaF2, thus creating a composite structure. The free energies of formation of CoF2 and MnF2 are (± 1700) J mol−1; {fx37-1} The third law analysis gives the enthalpy of formation of solid CoF2 as ΔH° (298·15 K) = −672·69 (± 0·1) kJ mol−1, which compares with a value of −671·5 (± 4) kJ mol−1 given in Janaf tables. For solid MnF2, ΔH°(298·15 K) = − 854·97 (± 0·13) kJ mol−1, which is significantly different from a value of −803·3 kJ mol−1 given in the compilation by Barinet al. 相似文献