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171.
Zhou Qihai 《计算机科学技术学报》1991,6(2):205-208
In this paper,an improved graphic representation for Structured Program Design--N-S-Z (Nassi-Shneiderman-Zhou Diagram) is proposed.It not only preserves the advantages of the conventional graphic and non-graphic representations,but also adds some new features which will enhance the representative power of the original diagram. 相似文献
172.
利用引进的制造技术和设备,制作出了 APT(STLRI)—1.78型系列化光纤连接器。 相似文献
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A novel milk-like Cu-thiourea colloid has been synthesized. Nanocrystalline quaternary copper sulfide Cu2FeSnS4 was obtained through the Cu-thiourea colloidal precursor cooperative conversion route at low temperature. The samples were characterized by means of X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy, and X-ray energy dispersive spectroscopy techniques. The reaction details and features were described and discussed. 相似文献
178.
In this paper, two brittle fracture problems are numerically simulated: the failure of a ceramic ring under centrifugal loading and crack branching in a PMMA strip. A three‐dimensional finite element package in which cohesive elements are dynamically inserted has been developed. The cohesive elements' strength is chosen to follow a modified weakest link Weibull distribution. The probability of introducing a weak cohesive element is set to increase with the cohesive element size. This reflects the physically based effect according to which larger elements are more likely to contain defects. The calculations illustrate how the area dependence of the Weibull model can be used to effectively address mesh dependency. On the other hand, regular Weibull distributions have failed to reduce mesh dependency for the examples shown in this paper. The ceramic ring calculations revealed that two distinct phenomena appear depending on the magnitude of the Weibull modulus. For low Weibull modulus, the fragmentation of the ring is dominated by heterogeneities. Whereas many cracks were generated, few of them could propagate to the outer surface. Monte Carlo simulations revealed that for highly heterogeneous rings, the number of small fragments was large and that few large fragments were generated. For high Weibull modulus, signifying that the ring is close to being homogeneous, the fragmentation process was very different. Monte Carlo simulations highlighted that a larger number of large fragments are generated due to crack branching. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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