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排序方式: 共有1338条查询结果,搜索用时 15 毫秒
141.
本文论述了17型车钩钩体生产过程的工艺改进,介绍了17型车钩钩体尾部裂纹产生的原因及采取的措施。通过工艺上采用保温暗冒口提高凝固过程补缩性,同时采用空心销孔芯提高芯子的退让性,并加强车钩钩体生产过程质量控制等措施,成功地解决了17型车钩钩体尾部裂纹问题,产品废品率由4.3%降到0.23%. 相似文献
142.
Production of Synthesis Gas via Dry Reforming of Methane over Co‐Based Catalysts: Effect on H2/CO Ratio and Carbon Deposition 下载免费PDF全文
Ahmed A. Ibrahim Muhammad Awais Naeem Anis H. Fakeeha Wasim Ullah Khan Ahmed S. Al‐Fatesh Ahmed E. Abasaeed 《化学工程与技术》2015,38(8):1397-1405
The effect of support type on synthesis gas production using Co‐based catalysts supported over TiO2‐P25, Al2O3, SiO2, and CeO2 was investigated. The catalysts were prepared by the incipient wet impregnation method and characterized by various techniques for comparison. Experiments were performed in a micro tubular reactor. The results revealed that all Co‐supported catalysts produced synthesis gas ratios of 1 and below and, thus, proved to be well‐suited for methanol and Fischer‐Tropsch syntheses. Co catalysts supported over TiO2‐P25 and Al2O3 provided better synthesis gas ratios and stability performances. The promotion of a Co/TiO2‐P25 catalyst with Ce had a substantial influence on its catalytic activity and the amount of carbon deposit. A Ce‐promoted catalyst diminished markedly the extent of carbon deposition and thus boosted the performance towards better activity and stability. 相似文献
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Hyun-Goo Kim Wha-Nam Myung K. Sumiyama K. Suzuki 《Journal of Alloys and Compounds》2003,360(1-2):168-172
The formation and chemical leaching effects of a nonequilibrium Al0.6(Fe25Cu75)0.4 powder produced by rod milling is described. X-ray diffraction, transmission electron microscopy, differential scanning calorimetry and vibrating sample magnetometry were used to characterize both the as-milled and leached specimens. After 400 h of milling, only the bcc AlFe phase with an amorphous phase was detected in the XRD patterns. The crystallite size for the bcc AlFe phase (110) after 400 h of milling was about 5.3 nm. The peak temperature and the crystallization temperature of the as-milled powders were 448.7 and 428.0 °C, respectively. Al atoms leaching from the as-milled bcc AlFe powders in the L1 condition did not alter the diffraction pattern significantly, even though Al atoms had been removed. After the L1 specimen was annealed at 500 °C for 1 h, the bcc AlFe phase transformed to the fcc Cu, Fe, and CuFe2O4 phases. The peak widths of L1 and L2 specimens were similar, but became broader than that of the as-milled powder. The saturation magnetization decreased with increasing milling time, and a value of 10.4 emu/g was reached after 400 h of milling. After cooling the specimen from 750 °C, the magnetization slowly increased at approximately 491.4 °C, indicating that the bcc AlFe phase had transformed to the fcc Cu and Fe phases. 相似文献
146.
采用合金化的方法得到快速凝固Cu75-xCr25Nix(X=0.5,1和3) 合金的凝固组织.利用带有能谱(EDS)的扫描电子显微镜(SEM)分析了富Cr相的形态、成分以及形成机制.结果显示,合金元素Ni扩大了Cu、Cr之间的固溶度; Cu75Cr25合金快速凝固过程中的液相分解得到抑制.Cu75-xCr25Nix合金富Cr液相分解组织的数量、尺寸、形貌较Cu75Cr25合金富Cr液相分解组织均有较大的变化.在Cu75-xCr25Nix组织中发现,除富Cr液相分解组织之间有聚集现象以外,还存在富Cr液相分解组织与富Cr枝晶间的聚集. 相似文献
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混氢原料油换热器是为安庆石化炼油厂制造的高压换热器,其主体材料为2.25Cr-1Mo+0Cr18Ni11Ti复合钢板,对制造过程中的封头成型、加热、热处理、组对等方面进行了简介。 相似文献
149.
F. H. Clarke Yu. S. Ledyaev M. L. Radulescu 《Journal of Dynamical and Control Systems》1997,3(4):493-518
Consider a mappingF from a Hilbert spaceH to the subsets ofH, which is upper semicontinuous/Lipschitz, has nonconvex, noncompact values, and satisfies a linear growth condition. We give
the first necessary and sufficient conditions in this general setting for a subsetS ofH to be approximately weakly/strongly invariant with respect to approximate solutions of the differential inclusion
. The conditions are given in terms of the lower/upper Hamiltonians corresponding toF and involve nonsmooth analysis elements and techniques. The concept of approximate invariance generalizes the well-known
concept of invariance and in turn relies on the notion of an ∈-trajectory corresponding to a differential inclusion.
Dedicated to Professor R. V. Gamkrelidze
The first and the third authors are supported in part by the Natural Sciences and Engineering Research Council of Canada and
Le Fonds FCAR du Québec.
The second author is visiting Rutgers University. Supported in part by the Russian Foundation for Fundamental Research, Grant
96-01-00219, by the Natural Sciences and Engineering Research Council of Canada, Le Fonds FCAR du Québec, and by the Rutgers
Center for Systems and Control (SYCON). 相似文献
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