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排序方式: 共有1130条查询结果,搜索用时 15 毫秒
1.
The behaviors of ferromagnetic transition metals of the first period: Fe, Co and Ni are examined within density functional theory calculations in two dimensional carbon extended networks using model structure LiC6. Around geometry optimized structures, the energy-volume equations of states considering non magnetic and spin polarized configurations established ferromagnetic ground states with magnetizations –reduced with respect to the metals’– of 2 μB for FeC6 and 1 μB for CoC6 while no magnetic solution could be identified for NiC6. In the D6h point group of the P6/mmm space group lm decomposition of the d states results with increasing energy into doublet state E1g with d(x2-y2) and d(xy); singlet state A1g d(z2) and doublet state E2g d(xz) and d(yz) lying on EF and responsible of the onset of magnetic moments. This was mirrored via molecular orbital approach with a construct of Fe embedded between two extended carbon networks thus validating the model structure proposed for TC6 compounds. The 100% polarization in one spin channel allows proposing potential uses in spintronics applications. 相似文献
2.
András Vasy 《Journal of Functional Analysis》2004,209(2):468-492
We show the exponential decay of eigenfunctions of second-order geometric many-body type Hamiltonians at non-threshold energies. Moreover, in the case of first-order and small second-order perturbations we show that there are no eigenfunctions with positive energy. 相似文献
3.
U型管内液柱振动的演示实验研究 总被引:1,自引:1,他引:0
根据实验结果,分析了影响U型管中液柱振动的各种因素,给出了获得好的演示效果的改进措施. 相似文献
4.
Paul Fabel 《Topology and its Applications》2007,154(3):635-638
With a certain natural topology, the fundamental group of a locally path connected metric space X becomes discrete if and only if X is semilocally simply connected. We include some related material and offer a counterexample to a similar result. 相似文献
5.
Jin-Mok Hur Chung-Seok Seo Sun-Seok Hong Dae-Seung Kang Seong-Won Park 《Reaction Kinetics and Catalysis Letters》2003,80(2):217-222
The concept of a novel electrochemical reduction process for the treatment of spent nuclear fuels in Li2O-LiCl molten salt was proposed and fresh tests using U3O8 powder were carried out to elucidate the reaction mechanism and verify the feasibility of the process. Electrolysis of Li2O and reduction of U3O8 powder took place simultaneously at the cathode part of the electrolysis cell via a catalytic EC mechanism and the conversion of U3O8 to U metal was more than 99%.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
Rashmi 《Solid State Communications》2005,134(3):217-222
A detailed analysis of nonlinear effects-electron switching and rectification, in InAlAs/InGaAs based Y-branch junction (YBJ) devices is presented to investigate the potential of YBJ for high frequency applications at 300 K. Results based on semi-classical simulations yield good qualitative agreement with measurements and previously reported theoretical and experimental results. The nonlinear parabolic behaviour of our device is attributed to device geometry and space charge effects. RF analysis shows that the YBJ has tremendous intrinsic potential to function as a frequency doubler and microwave rectifier when operated in the parabolic regime. The present analysis serves as a tool to optimize the bias conditions for RF measurements and to estimate the effect of interconnects and parasitic elements on the RF performance of real devices. 相似文献
7.
Summary. We introduce linear semi-implicit complementary volume numerical scheme for solving level set like nonlinear degenerate diffusion
equations arising in image processing and curve evolution problems. We study discretization of image selective smoothing equation
of mean curvature flow type given by Alvarez, Lions and Morel ([3]). Solution of the level set equation of Osher and Sethian
([26], \[30]) is also included in the study. We prove and estimates for the proposed scheme and give existence of its (generalized) solution in every discrete time-scale step. Efficiency
of the scheme is given by its linearity and stability. Preconditioned iterative solvers are used for computing arising linear
systems. We present computational results related to image processing and plane curve evolution.
Received April 25, 2000 / Revised version received June 11, 2001 / Published online November 15, 2001 相似文献
8.
Brenton R. Clarke 《Journal of multivariate analysis》2007,98(5):916-931
In this paper, we consider the estimation of a parameter of interest where the estimator is one of the possibly several solutions of a set of nonlinear empirical equations. Since Newton's method is often used in such a setting to obtain a solution, it is important to know whether the so obtained iteration converges to the locally unique consistent root to the aforementioned parameter of interest. Under some conditions, we show that this is eventually the case when starting the iteration from within a ball about the true parameter whose size does not depend on n. Any preliminary almost surely consistent estimate will eventually lie in such a ball and therefore provides a suitable starting point for large enough n. As examples, we will apply our results in the context of M-estimates, kernel density estimates, as well as minimum distance estimates. 相似文献
9.
The category of small covariant functors from simplicial sets to simplicial sets supports the projective model structure [B. Chorny, W.G. Dwyer, Homotopy theory of small diagrams over large categories, preprint, 2005]. In this paper we construct various localizations of the projective model structure and also give a variant for functors from simplicial sets to spectra. We apply these model categories in the study of calculus of functors, namely for a classification of polynomial and homogeneous functors. In the n-homogeneous model structure, the nth derivative is a Quillen functor to the category of spectra with Σn-action. After taking into account only finitary functors—which may be done in two different ways—the above Quillen map becomes a Quillen equivalence. This improves the classification of finitary homogeneous functors by T.G. Goodwillie [T.G. Goodwillie, Calculus. III. Taylor series, Geom. Topol. 7 (2003) 645-711 (electronic)]. 相似文献
10.
During the last 55 years there have been many results concerning conditions that force a ring to be commutative. These results were stimulated by Jacobson's famous result and were extensively developed by Herstein. This paper will survey the area by organizing the results according to whether they come from variations on Herstein's conditions, depend on general polynomial conditions, depend on the presence of a derivation, or whether a ring has special properties that make commutativity more easily accessible. Finally, the most recent conditions concern product sets and lead to results in a new area of inquiry. 相似文献