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991.
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Crack initiation and stable crack growth under monotonic loading in steels has been studied using an elastic-plastic finite element analysis. The fracture criterion used for crack initiation and stable crack growth was the critical strain energy density. In addition the shift core method for the analysis of crack extension was used. In the shift core modelling method, crack advance is simulated by moving the coordinates of the core region which surrounds the crack tip, to obtain the stiffness reduction. Simultaneously the core itself geometrically undergoes a simple rigid-body motion or translation during the crack extension. The analytically calculated and experimentally measured load for crack initiation and the subsequent stable crack growth agreed well. 相似文献
995.
G. A. Stergioudis 《Zeitschrift für Physik B Condensed Matter》1993,93(1):1-4
The tendency of boron-containing, iron-based glasses to show non monotonic changes of Curie Temperature (T
c
) and room temperature saturation magnetization (SM) was examined by magnetic measurements and Mossbauer spectroscopy. Depending on B/Fe ratio theT
c
and SM first increased up to a maximum value and then steadily decreased, probably because of a shortrange ordering, due to the strong chemical interaction between iron and boron atoms, leading iron atoms in vicinity with Fe-atoms rather than another TM-atom. Finally, the phenomenon becomes analogous to the order-disorder phenomenon in crystalline alloys. An observed unusual crystallization behaviour, consisting of heterogeneous nucleation, was also ascribed to this ordering, which leads to the formation of associations, acting as the first nuclei of crystallization. 相似文献
996.
997.
G. A. Dvoyan A. G. Gulyan R. M. Martirosyan G. A. Pirumyan A. S. Agadzhanyan 《Radiophysics and Quantum Electronics》1997,40(9):793-797
We describe a new method of constructing a device for simultaneous measurement of the relative amplitude and phase difference
of microwave signals, using complex phase manipulation of input signals. It is shown that systematic errors of measurement
are significantly lower in the proposed amplitude and phase meter. Root-mean-square values are obtained for a system with
nonideal elements. A block diagram of the device is presented and its principal characteristics are described.
Institute of Radiophysics and Electronics, Armenian Academy of Sciences, Erevan. Translated from Izvestiya Vysshikh Uchebnykh
Zavedenii, Radiofizika, Vol. 40, No. 9, pp. 1182–1188, September, 1997. 相似文献
998.
999.
Experiments employing photoreflectance spectroscopy have uncovered band bending due to electrically active defects at the Si(1 1 1)–SiO2 interface after sub-keV Ar+ ion bombardment. The band bending of about 0.5 eV resembles that for Si(1 0 0)–SiO2, and both interfaces exhibit two kinetic regimes for the evolution of band bending upon annealing due to defects healing. The healing takes place about an order of magnitude more quickly at the (1 1 1) interface, however, probably because of less fully saturated bonding and higher compressive stress. 相似文献
1000.