共查询到18条相似文献,搜索用时 125 毫秒
1.
2.
3.
4.
采用X射线衍射、电子衍射及透射电子显微技术研究了Fe73 .5 Cu1Nb3 Si13 .5 B9非晶合金在 82 3K ,1~ 5GPa下退火所形成的纳米晶结构 ,高压实验采用Belt型压力装置 .结果表明 ,压力没有改变合金结晶相的类型 ,但对其纳米晶结构的形成有重要影响 .当压力从常压增加到 5GPa时 ,结晶相α Fe固溶体 (α Fe相 )的尺寸从 1 1 .5nm减小至 5nm .当压力低于 2GPa时 ,α Fe相的体积分数随压力的增高而增加 ,然后随压力进一步增高 (P >2GPa)而减小 .还讨论了压力影响Fe73 .5 Cu1Nb3 Si13 .5 B9纳米晶合金形成的机制 . 相似文献
5.
6.
本文研究了Y替代Ca对Bi2Sr2Ca1-xYxCu2O8+y,超导体晶体结构和电子状态的影响,发现:Y替代Ca后至少使得Bi-O双层中所夹的一层额外的氧原子发生了变化,沿b轴方向的无公度超格子的调制周期从4.7b连续减小到大约为4.0b;并发现当Y完全替代Ca时,则同时存在大约为4b和8b的调制周期.用XPS进一步研究其电子状态变化的结果表明,超导电性的变化不是由于晶体结构的微小变化引起的,而主要是由CuO2层中O2p轨道空穴的逐步填充所致.结果明确表明,对于该替代体系依然是当Cu离子3d轨道存在一个空穴时(3d9态)对应于强关联的反铁磁绝缘体,而当CuO2层中氧离子2p轨道存在额外的空穴时(即3d9L态)对应于超导体. 相似文献
7.
8.
9.
10.
本文研究了一类含临界指数的p-Kirchhoff型方程.利用变分方法与集中紧性原理,通过证明对应的能量泛函满足局部的(PS)_c条件,得到了这类方程非平凡解的存在性,推广了关于Kirchhoff型方程的相关结果. 相似文献
11.
Nguyen Quang Do Thong 《K-Theory》1993,7(5):429-441
The well-known formula of Riemann-Hurwitz gives the change of genuses in ann-fold covering of compact connected Riemann surfaces. In Iwasawa theory, there existp-adic analogues which give the change of certain ±-invariants in ap-extension ofCM number fields. Using functorial and arithmetical properties ofK
3, we extend such Riemann-Hurwitzp-adic formulas to non-CM fields, assuming some restrictive hypotheses on the capitulation ofK
2. 相似文献
12.
Douglas R. Anderson 《K-Theory》1990,4(6):569-590
Let Z be a boundedness control space and p: X Z be a continuous map. The boundedly controlled Whitehead group Wh
bc
(X, p) is defined to be a quotient of the boundedly controlled K
1-group K
1
bc
(X, p) by a certain subgroup whose generators are explicitly given. In general, little is known about this subgroup and it is even possible that it vanishes; i.e. that the boundedly controlled K
1 and Whitehead groups are identical. This paper examines the structure of this subgroup in the case when p is the open cone on a PL map between compact polyhedra. As a byproduct, it calculates Wh
bc
(X, p) in some of these cases.Partially supported by the NSF under grant number DMS-8803149. 相似文献
13.
Kazuya Kato 《K-Theory》2005,34(2):99-140
We compute K1 of completed group rings of some two dimensional p-adic Lie groups.
Dedicated to Professor Spencer Bloch on his sixtieth birthday 相似文献
14.
This paper merges some classifications of G-M-type Banach spaces simplifically, discusses the condition of K
0(B(X)) = 0 for operator algebra B(X) on a Banach space X, and obtains a result to improve Laustsen's sufficient condition, gives an example to show that X ≈ X
2 is not a sufficient condition of K
0(B(X)) = 0. 相似文献
15.
A new series representation of the exact distribution of Hotelling's generalized T02 statistic is obtained. Unlike earlier work, the series representation given here is everywhere convergent. Explicit formulae are given for both the null and the non-central distributions. Earlier results by [1], 215–225), which are convergent on the interval [0, 1), are also derived quite simply from our formulae. The paper therefore provides a solution to the long standing problem of the exact distribution of the T02 statistic in the general case. 相似文献
16.
Roozbeh Hazrat 《K-Theory》2002,27(4):293-328
Employing Bak's dimension theory, we investigate the nonstable quadratic K-group K
1,2n
(A, ) = G
2n
(A, )/E
2n
(A, ), n 3, where G
2n
(A, ) denotes the general quadratic group of rank n over a form ring (A, ) and E
2n
(A, ) its elementary subgroup. Considering form rings as a category with dimension in the sense of Bak, we obtain a dimension filtration G
2n
(A, )
G
2n
0(A, )
; G
2n
1(A, )
...
E
2n
(A, ) of the general quadratic group G
2n
(A, ) such that G
2n
(A, )/G
2n
0(A, ) is Abelian, G
2n
0(A, )
G
2n
1(A, )
... is a descending central series, and G
2n
d(A)(A, ) = E
2n
(A, ) whenever d(A) = (Bass–Serre dimension of A) is finite. In particular K
1,2n
(A, ) is solvable when d(A) < . 相似文献
17.
Mariya Ishteva Lieven De Lathauwer P.-A. Absil Sabine Van Huffel 《Numerical Algorithms》2009,51(2):179-194
An increasing number of applications are based on the manipulation of higher-order tensors. In this paper, we derive a differential-geometric
Newton method for computing the best rank-(R
1, R
2, R
3) approximation of a third-order tensor. The generalization to tensors of order higher than three is straightforward. We illustrate
the fast quadratic convergence of the algorithm in a neighborhood of the solution and compare it with the known higher-order
orthogonal iteration (De Lathauwer et al., SIAM J Matrix Anal Appl 21(4):1324–1342, 2000). This kind of algorithms are useful for many problems.
This paper presents research results of the Belgian Network DYSCO (Dynamical Systems, Control, and Optimization), funded by
the Interuniversity Attraction Poles Programme, initiated by the Belgian State, Science Policy Office. The scientific responsibility
rests with its authors. Research supported by: (1) Research Council K.U.Leuven: GOA-Ambiorics, CoE EF/05/006 Optimization
in Engineering (OPTEC), (2) F.W.O.: (a) project G.0321.06, (b) Research Communities ICCoS, ANMMM and MLDM, (3) the Belgian
Federal Science Policy Office: IUAP P6/04 (DYSCO, “Dynamical systems, control and optimization”, 2007–2011), (4) EU: ERNSI.
M. Ishteva is supported by a K.U.Leuven doctoral scholarship (OE/06/25, OE/07/17, OE/08/007), L. De Lathauwer is supported
by “Impulsfinanciering Campus Kortrijk (2007–2012)(CIF1)” and STRT1/08/023. 相似文献
18.
A subset MX of a normed linear space X is a Chebyshev set if, for every xX, the set of all nearest points from M to x is a singleton. We obtain a geometrical characterisation of approximatively compact Chebyshev sets in c0. Also, given an approximatively compact Chebyshev set M in c0 and a coordinate affine subspace Hc0 of finite codimension, if M∩H≠, then M∩H is a Chebyshev set in H, where the norm on H is induced from c0. 相似文献