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991.
Buckling behaviour of imperfect spherical shells subjected to different load conditions 总被引:2,自引:0,他引:2
The paper deals with an analysis of the bifurcation and initial post-buckling behaviour of highly imperfection-sensitive large spherical .shells, such as cargo tanks for ship transportation of liquefied natural gas and large spherical containment shells for nuclear power plants. The numerical analysis procedure has sufficient generality to treat shells of revolution with arbitrary curved generators and with arbitrary variation of the thickness. The shells can be subjected to non-axisymmetric time-varying loadings. The purpose of the paper is to present simple procedures for scantling selections in the initial design phase and to propose an analysis procedure for verification of the final design of optimized thin-walled spherical shells. 相似文献
992.
K''Andrea C. Bickerstaff Michael J. Schulte Earl E. Swartzlander 《The Journal of VLSI Signal Processing》1995,9(3):181-191
As developed by Wallace and Dadda, a method for high-speed, parallel multiplication is to generate a matrix of partial products
and then reduce the partial products to two numbers whose sum is equal to the final product. The resulting two numbers are
then summed using a fast carry-propagate adder. This paper presents Reduced Area multipliers, which employ a modified reduction
scheme that results in fewer components and less interconnect overhead than either Wallace or Dadda multipliers. This reduction
scheme is especially useful for pipelined multipliers, because it minimizes the number of latches required in the reduction
of the partial products. The reduction scheme can be applied to either unsigned (sign-magnitude) or two's complement numbers.
Equations are given for determining the number of components and a method is presented for estimating the interconnect overhead
for Wallace, Dadda, and Reduced Area multipliers. Area estimates indicate that for non-pipelined multipliers, the reduction
in area achieved with Reduced Area multipliers ranges from 3.7 to 6.6 percent relative to Dadda multipliers, and from 3.8
to 8.4 percent relative to Wallace multipliers. For fully pipelined multipliers, the reduction in area ranges from 15.1 to
33.6 percent relative to Dadda multipliers, and from 2.9 to 9.0 percent relative to Wallace multipliers. 相似文献
993.
本文主要研究了滤束扫描合成孔径雷达的杨像处理方法,分析了SCANSAR的工作原理、信号格式、信号结构和信号参数限制,成像处理算法包括块数据成像算法和块图像拼接算法两部分,频谱分析法和时域频域混合相关法被用于数据成像,块图像的拼接是利用时间有系剪裁块图像再顺次拼接,计算机仿真验证了本文提出的SCANSAR信号格式和成像算法的可行性。 相似文献
994.
To study the effect of ischemia reperfusion injury on microvascular reactivity and tissue metabolism in skeletal muscle, a Sprague-Dawley rat cremaster muscle was prepared as a tourniquet ischemia model and subjected to 2 hr ischemia followed by 1 hr reperfusion to simulate the timing of ischemia during microvascular surgery. The dose-response curve of arteriolar reactivity to norepinephrine, lipid peroxidation, and ultrastructure of capillaries was determined in both the control and postischemic reperfusion stages. Judging from the results, we summarize our observations as follows: (1) Postischemic reperfusion significantly increased arteriolar reactivity to norepinephrine, in which the EC50 for vasoconstriction decreased in all three orders of arterioles. These results suggest that reperfusion could have impaired the vasodilation control mechanism, possibly being endothelium dependent. (2) Lipid peroxidation increased sixfold in the reperfusion group, suggesting that oxygen free radicals have produced significant tissue damage under the created conditions. (3) Significant endothelial damage in the capillaries shown by electron microscope observation supports these studies, indicating that ischemia/reperfusion in clinically transplanted skeletal muscles could cause significant damage to the tissue microcirculation both physiologically and metabolically. 相似文献
995.
996.
Li Xi Zuoyan Peng Wei Fan Kui Guo Gu Jianmin Muyu Zhao Wu Guoqiang 《Materials Science and Engineering: B》1996,40(2-3):147-152
SrMgxTi1 - xO3 nanocrystals (x = 0.1–0.6) were synthesized by the stearic acid gel method. Powder samples were characterized by X-ray diffraction and X-ray photoelectron (XP) spectroscopy. The results showed that the lattice parameter a and the O 1s XP spectrum changed not only with the Mg content x but also with the grain size d of the samples. The conductivity of a thick film specimen fabricated on an aluminium oxide wafer was investigated in a nitrogen—oxygen atmosphere. 相似文献
997.
Weitang Li Zhenghui Li Shifu Zhu Shujun Yin Beijun Zhao Guanxiong Chen 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1996,370(2-3):435-437
Instead of the temperature oscillation method (TOM), a modified vapor growth method was applied in this paper to grow large HgI2 crystals with fewer lattice defects by providing a relatively stable temperature field during growth. And a new processing technique of HgI2 crystals was developed for detector fabrication by merging solution string-sawing and hand-cleaving. The lattice deformations caused during cleaving were reduced greatly by eliminating passivated layers on the sawed crystal platelets before cleaving. 相似文献
998.
镶嵌在CaF2介质中纳米Cu团簇微观结构的研究 总被引:2,自引:0,他引:2
利用磁控溅射产生金属Cu团簇,同时蒸发CaF2介质,将Cu团簇包埋在CaF2介质中,团簇大小可通过改变溅射气压控制,用TEM研究了嵌埋团簇的结构,分析结果表明:Cu团簇呈三角状多晶结构,团簇大小为10 ̄70nm,基质CaF2晶体也为多晶结构,Cu团簇的晶格常数在包埋状态下发生了膨胀,膨胀率大约在16%左右。 相似文献
999.
步进式加热炉炉温优化设定模型及软件开发 总被引:1,自引:0,他引:1
针对线材厂步进式加热炉实际工况,提出了基于经验规则的炉温优化设定模型和在线自学习获取知识的思想,并以炉温优化设定模型为核心,开发出加热炉计算机控制系统的优化运行软件。 相似文献
1000.
OntheRealizationofCurrent-ModeContinuousTimeOperationalTransconductanceCapacitanceFilter¥GuoJingboandHanQingquan(ChangchunPos... 相似文献