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1.
Effect of deformation route on microstructural development in aluminum processed by equal channel angular extrusion 总被引:3,自引:0,他引:3
Pei-Ling Sun Po-We Kao Chih-Pu Chang 《Metallurgical and Materials Transactions A》2004,35(4):1359-1368
Aluminum has been deformed by equal channel angular extrusion (ECAE) to obtain submicron-grained structures under different
deformation routes. The deformation routes were varied by rotating billets through 0, 90, and 180 deg between each extrusion
pass, and were designated as route A, BC, and C, respectively. Based on quantitative microstructural analysis, the effectiveness of the deformation route is shown
to depend upon the different definition used. The order of effectiveness is (a) A > BC > C for both 90 and 120 deg dies, in terms of the generation of high-angle grain boundaries (HAGBs); (b) BC > C > A for both 90 and 120 deg dies, in terms of the formation of equiaxed shape of grains; and (c) BC > A > C for 90 deg die and BC ∼ A > C for 120 die, in terms of reducing grain size. It is suggested that the generation of HAGBs can be related to the
accumulation of nonredundant strain, while the shape and orientation of grains may be linked to the shearing patterns of the
deformation route. 相似文献
2.
DI Timokhin AV Istomin TS Shushkova TG Voronel' IG Mikha?lov 《Canadian Metallurgical Quarterly》1997,(2):19-21
Based on generalization and analysis of instructions and guidelines for therapeutical and prophylactic diets of workers, ways of its optimization were proposed, by using bifide-containing acid dairy products as a preventive agent against possible occupational diseases caused by occupational factors. 相似文献
3.
4.
Cancer statistics, 1993 总被引:1,自引:0,他引:1
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7.
A unified group technology implementation using the backpropagation learning rule of neural networks
Two engineering problems in implementing Group Technology are part family formation and part classification. Regardless of the approach adopted for the formation and classification, a critical problem is how to maintain consistency. The consistency problem can be addressed most effectively if the formation and classification is a single procedure rather than two separate procedures. A feedforward neural network using the Backpropagation learning rule is adopted to automatically generate part families during the part classification process. The spontaneous generalization capability of the neural network is utilized in classifying the parts into the families and creating new families if necessary. A heuristic algorithm using the neural network is described with an illustrative example. 相似文献
8.
The relatively fast diffusion of Au atoms in eutectic PbSn matrix is considered one of the contributing factors to the Au
embrittlement problem. In this study, we further investigated the Au embrittlement problem in high-Sn solders. Experimentally,
Sn3.5Ag (wt.%) spheres with 500-μm diameter were soldered over the Au/Ni soldering pads. It was found that some of the AuSn4 needles that formed after reflow inside the solder migrated back to the solder/pad interface during thermal aging. However,
the migration kinetics in high-Sn solders was slower compared to that in eutectic PbSn. The difference in migration kinetics
of AuSn4 in eutectic PbSn and SnAg was ascribed to the difference in the magnitudes of the Au flux and the Ni flux. In eutectic PbSn,
the Au flux was much greater than that of the Ni flux, and the Au and Ni flux were in the same order of magnitude in eutectic
SnAg. The relative magnitude of the Au and Ni flux changed in eutectic PbSn and SnAg because the homologous temperatures of
PbSn and SnAg were different. 相似文献
9.
LW Delbridge NA Younes AI Guinea TS Reeve P Clifton-Bligh BG Robinson 《Canadian Metallurgical Quarterly》1998,168(4):153-156
Twenty-two cases of ameloblastoma and ten cases of adenomatoid odontogenic tumour (AOT) were analyzed comparatively by the AgNOR technique. Ameloblastomas were distributed into three groups according to their clinical behaviour: primary lesions without recurrences (PLWTR), 5 cases; primary lesions with recurrences (PLWR), 4 cases; and recurrences, 13 cases. The cases were also regrouped according to their histological pattern: follicular (9 cases), plexiform (7 cases), acanthomatous (4 cases) and unicystic (2 cases). Considering histological patterns, there was a significant statistical difference only between follicular and plexiform types. There were no significant differences between the group of ameloblastomas and the group of AOTs or between the three groups of ameloblastomas with different clinical behaviour. Our results strongly suggest that the distinct clinical behaviour of ameloblastomas and AOT is not correlated with their cellular proliferation ratio. Thus, the infiltrative ability of the ameloblastomas is probably not related to the cellular proliferation index of these tumours. 相似文献
10.
The postpartum period is an ideal time to begin contraception, as women are more highly motivated to adopt contraception at this time and it is convenient for both patients and service providers. For intrauterine device (IUD) contraception, this period offers other advantages, such as ease of insertion and minimal adverse impacts on breastfeeding. Among early studies, most postpartum insertions were performed anywhere from a few hours to seven days or more after delivery, and retention of the IUD in the uterus was poor. Since the 1970s, immediate postplacental insertion (IPPI), i.e., IUD insertion performed within 10 minutes after placental delivery, has been advocated, and fairly, low expulsion rates have been reported. Up to now, IPPI has not been widely accepted in clinics because its expulsion rate still appears to be higher than that of interval insertion. In order to further study IPPI and perfect this contraceptive technique, it is essential to comprehensively review IPPI results and compare the Chinese experience with that of the rest of the world. 相似文献