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91.
利用AES、WDS和x-射线衍射等方法,研究了杜美丝表面层、铁镍芯与覆铜层界面的微观结构与特性。结果表明:良好的表面层应由Cu2O和非晶态的硼砂构成;玻璃与杜美丝的润湿性决定于表面层的净化程度和构成及加热条件。 相似文献
92.
Qidong Cao Mark A. Mcknew 《International Journal of Flexible Manufacturing Systems》1994,6(2):155-172
A new optimization model is discussed for the design of cellular manufacturing systems. It is based on an integer programming formulation that updates some other models by eliminating redundant machine assignment and cost coefficients dependent on cell configuration. To reduce computational burdens, a simplified integer programming model and a decomposition algorithm are proposed. Several computer solutions were performed to evaluate the performance of the new model. The computational results are discussed. 相似文献
93.
利用俄歇电子能谱研究了Cr/SiO2薄膜在热处理过程中的界面扩散反应机理、界面反应动力学过程及界面反应产物。研究结果表明,Cr/SiO2体系的界面还原反应主要是Cr与SiO2的反应,其还原反应产物是CrSix和Cr2O3物种。界面还原反应的速度与反应时间的平方根成正比,其界面还原反应过程受Cr向SiO2层的扩散过程所控制,界面还原反应的表观活化能为72.5kJ/mol(约0.75eV)。 相似文献
94.
A 43-year-old male and a 39-year-old male presented with multiple pituitary adenomas with two distinct histological types. The first patient who had multiple endocrine neoplasia type 1 had developed acromegaly due to a growth hormone-releasing hormone (GHRH)-producing pancreatic tumor. Both plasma GHRH and growth hormone (GH) levels decreased to normal after resection of the pancreatic tumor. However, the plasma GH level gradually increased again and magnetic resonance imaging revealed pituitary adenoma formation. Histological examination revealed two different histological types of pituitary adenoma: GH cell adenoma and null cell adenoma. The second patient, with no such genetic condition, had a non-functioning pituitary adenoma. Histological examination revealed two different histological types of silent GH cell adenoma and silent gonadotroph adenoma. Careful histological examination is required to exclude the possibility of multiple pituitary adenomas. 相似文献
95.
96.
The span-depth ratios of coupling beams to interconnect shear walls are generally small, so that brittle shear failure may occur and lead to reduced ductility. In order to improve the ductility of coupling beams for earthquake loading, a new type of ductile coupling beam is proposed in this paper. Along the middle depth of this beam, a slit through the entire thickness (a narrow hole) near each end and two lateral keyways along the remaining middle part of the span are made. The reductions of the stiffness under service load and the ultimate carrying capacity of the beam due to the weakening mentioned above are small and the ductility is greatly increased. Tests of 4-storey walls interconnected by coupling beams in three different constructions (monolithic beams, beams with a through-slit and new-type beams) indicated that shear walls with the new coupling beams possess the best aseismic behaviours under cyclic loading. The proposed new coupling beam has been used in a high-rise building. 相似文献
97.
我国炼油技术开发的若干思考与建议 总被引:12,自引:4,他引:8
分析了我国炼油工业面临的挑战,世界炼油工业的发展趋势,提出了我国炼油技术开发要围绕符合国情的清洁燃料生产技术,炼油与化工结合的炼油技术,适合现有炼油装置技术改造、提高技术水平,降低加工成本的技术,渣油转化技术,煤制油,天然气制油技术,炼油厂智能化的技术,减少炼油厂烟尘排放的技术等7个方面开展工作的具体建议。 相似文献
98.
Lei Cao 《IEEE transactions on image processing》2007,16(9):2384-2388
In this paper, we consider the unequal error protection (UEP) for progressive image transmission when the coded packet size is fixed. First, we prove that, for the source code with convex rate-distortion (R-D) function and practically used channel codes, the channel code rate for each packet in the optimal rate allocation is nondecreasing indeed. Then, we give an upper bound for the channel code rate of the last packet so that the number of rate allocations in the exhaustive search can be predicted. Further, we propose a heuristic optimization method which has low complexity and obtains performance approaching to the optimal solutions for various channel conditions and transmission rates. 相似文献
99.
100.