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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
We study a generalized Crank–Nicolson scheme for the time discretization of a fractional wave equation, in combination with
a space discretization by linear finite elements. The scheme uses a non-uniform grid in time to compensate for the singular
behaviour of the exact solution at t = 0. With appropriate assumptions on the data and assuming that the spatial domain is convex or smooth, we show that the
error is of order k
2 + h
2, where k and h are the parameters for the time and space meshes, respectively. 相似文献
992.
993.
Microstructure and oxygen stoichiometry of YBaCuO films manufactured by laser ablation are investigated. Dependence of the specific electrical resistivity and superconducting
parameters of films on microstructure and oxygen stoichiometry is demonstrated. Conditions of deposition are determined, under
which films with minimum microstructure defects and good conducting properties are formed.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 41–45, February, 2007. 相似文献
994.
The growth mechanism of the peritectic η phase involving the peritectic reaction and peritectic transformation in Cu-70%Sn alloy was investigated under directional
solidification. The results show that a major growth mechanism in thickening of the peritectic η-layer is not the peritectic reaction but the peritectic transformation. The transformation temperature and isothermal time
play crucial roles in determining the volume fraction and the thickness of the peritectic η phase. With the increase of the temperature and isothermal time, the volume fraction of the peritectic η phase increases. The regressed data show that the relationship between the thickness of η phase (Δx) and the transformation temperature (T) meets the following equation In Δx=6.5−1673 1 / T. Additionally, there exists a relationship between the thickness of the η phase (Δx) and the isothermal time (t) at the 9 mm solidification distance below the peritectic reaction interface, Δx=0.72t
1/2, which is consistent with the theoretical model.
Supported by the National Science Foundation of China (Grant No. 50395102) 相似文献
995.
996.
Studies in the field of radical copolymerization of N-vinylsuccinimide were summarized, theeffect of the reaction medium on the process kinetics was examined. Factors governing the relative activity ofthe monomers were revealed, and ways to control the reactivity of N-vinylsuccinimide in binary copolymerizations were suggested. 相似文献
997.
In the present paper, a new two-parameter inverted equation of state (EOS) is developed which is found to be working very
well in the high-pressure region. To check its success and validity, this EOS has been applied in a number of solids. The
computed volume compression is found to be in very good agreement with the experimental data in the whole range of pressure
in all the solids. The minimum and the maximum pressure range used in the present study is 0–320 kbar and 0–3000 kbar, respectively. 相似文献
998.
Anders Frankild 《Mathematische Zeitschrift》2003,244(3):615-630
We study the vanishing properties of local homology of complexes of modules without assuming that its homology is artinian.
Using vanishing results for local homology and cohomology we prove new vanishing results for Ext- and Tor-modules.
Received: 1 August 2002; in final form: 23 September 2002 /
Published online: 16 May 2003
Mathematics Subject Classification (1991): 13C12, 13D07, 13D45. 相似文献
999.
A column generation (CG) approach for the solution of timetabling problems is presented. This methodology could be used for various instances of the timetabling problem, although in this paper the solution of the high-school situation in Greece is presented. The results obtained show clearly that the CG approach that has been extremely successful in recent years in the solution of airline crew scheduling problems could also be very efficient and robust for the solution of timetabling problems. Several large timetabling problems corresponding to real problems have been successfully solved, with the solutions obtained feasible and of very high quality in accordance with the problem definition. In addition, none of the solutions contained any idle hour for any of the teachers, which was one of the main goals of this optimization effort. 相似文献
1000.