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41.
42.
Deguang Han 《应用数学学报(英文版)》1994,10(2):213-219
In this paper we will prove some theorems on theM-ideals of compact operators and the best approximation of quasitriangular operator algebras. These results improve and extend the known results in [4, 5, 7].This work is supported in part by the National Natural Science Foundation of China. 相似文献
43.
Weimin Han 《Mathematical Methods in the Applied Sciences》1994,17(7):487-508
The paper is devoted to a posteriori quantitative analysis for errors caused by linearization of non-linear elliptic boundary value problems and their finite element realizations. We employ duality theory in convex analysis to derive computable bounds on the difference between the solution of a non-linear problem and the solution of the linearized problem, by using the solution of the linearized problem only. We also derive computable bounds on differences between finite element solutions of the nonlinear problem and finite element solutions of the linearized problem, by using finite element solutions of the linearized problem only. Numerical experiments show that our a posteriori error bounds are efficient. 相似文献
44.
A uniqueness theorem for two distinct non-constant meromorphic functions that share three values of finite weights is proved, which generalizes two previous results by H.X. Yi, and X.M. Li and H.X. Yi. As applications of it, many known results by H.X. Yi and P. Li, etc. could be improved. Furthermore, with the concept of finite-weight sharing, extensions on Osgood-Yang's conjecture and Mues' conjecture, and a generalization of some prevenient results by M. Ozawa and H. Ueda, ect. could be obtained. 相似文献
45.
46.
李斌 《数学的实践与认识》2006,36(8):25-30
在分析我国房地产自有资本收益率操作中所存在问题的基础上,论述了自有资本收益率的实质是自有资金直接资本化率,并在房地产持有期小于抵押贷款期以及房地产持有期和土地批租年限相同的两种情况下,推导出了与土地有限期使用制度相适应的房地产资本化率和自有资本收益率的计算方法,提出了利用债务保障比率的取值范围检验资本化率合理性的基本公式. 相似文献
47.
p型未掺杂富锌ZnO薄膜的形成和性能研究 总被引:1,自引:1,他引:0
以高纯ZnO为靶材,氩气为溅射气体,利用射频磁控溅射技术在石英衬底上生长出纤锌矿结构的富锌ZnO薄膜.薄膜沿(002)择优取向生长,厚约为1.2μm,呈现电绝缘特性.将溅射的ZnO薄膜在10-3Pa,510~1 000 K的温度范围等温退火1 h,室温Hall测量结果表明ZnO薄膜的导电性能经历了由绝缘—n型—p型—n型半导体的变化.XPS测试表明ZnO薄膜的Zn/O离子比随退火温度的升高而降低,但一直是富锌ZnO,说明未掺杂的富锌ZnO也可以形成p型导电.p型未掺杂富锌ZnO薄膜的形成可归因于VZn受主浓度可以克服VO和Zni本征施主的补偿效应. 相似文献
48.
Z.X. Cheng S.J. ZhangF. Song H.C. GuoJ.R. Han H.C. Chen 《Journal of Physics and Chemistry of Solids》2002,63(11):2011-2017
Erbium and ytterbium codoped double tungstates NaY(WO4)2 crystals were prepared by using Czochralski (CZ) pulling method. The absorption spectra in the region 290-2000 nm have been recorded at room temperature. The Judd-Ofelt theory was applied to the measured values of absorption line strengths to evaluate the spontaneous emission probabilities and stimulated emission cross sections of Er3+ ions in NaY(WO4)2 crystals. Intensive green and red lights were measured when the sample were pumped by a 974 nm laser diode (LD), especially, the intensities of green upconversion luminescence are very strong. The mechanism of energy transfer from Yb3+ to Er3+ ions was analyzed. Energy transfer and nonradiative relaxation played an important role in the upconversion process. Photoexcited luminescence experiments are also fulfilled to help analyzing the transit processes of the energy levels. 相似文献
49.
Acoustic vector sensor signal processing 总被引:2,自引:0,他引:2
SUN Guiqing LI Qihu ZHANG Bin 《声学学报:英文版》2006,25(1):1-15
Acoustic vector sensor simultaneously, colocately and directly measures orthogonal components of particle velocity as well as pressure at single point in acoustic field so that is possible to improve performance of traditional underwater acoustic measurement devices or detection systems and extends new ideas for solving practical underwater acoustic engineering problems. Although acoustic vector sensor history of appearing in underwater acoustic area is no long, but with huge and potential military demands, acoustic vector sensor has strong development trend in last decade, it is evolving into a one of important underwater acoustic technology. Under this background, we try to review recent progress in study on acoustic vector sensor signal processing, such as signal detection, DOA estimation, beamforming, and so on. 相似文献
50.
The ab initio calculations were performed at the RHF/4-31G level with the reaction pathways of the iso-merization and dehydrogenation of methylnitrene by the intrinsic reaction coordinate method. The results show that the transformation from methylnitrene to methylenimine would be very easy. This accountes for the experimental fact that one couldn' t find the methylnitrene, but only obtained the methylenimine in the pyrolysis of methyl azide. The mode-selective study reveals the reaction coordinates (IRC) of isomerization and dehydrogenation of methylnitrene are associated with the molecular deformation mode of 1191 cm-1 and the methyl group unsymmetrical stretch mode, respectively. The coupling between normal coordinates is favourable to select the reaction channel of isomerization. 相似文献