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排序方式: 共有73条查询结果,搜索用时 78 毫秒
1.
Atomic-scale friction of a tungsten tip on a graphite surface 总被引:1,自引:0,他引:1
2.
We construct two bases of the natural numbers B1 and B2, eachof order two, such that (B1 + B2 (n) <n+c/(log n). For alower estimate, it is proved that if B2 and are two bases, eachof order two, then (B1+B2)(n) > n. Generalisations to sumsof bases of order h > 2 are also given. 相似文献
3.
Data are presented which show that when a polymer contains an appreciable amount of low molecular weight species below the diffusion limit of the osmometer membrane, the osmotic molecular weight, M?n, is generally higher than the M?n calculated from gel-permeation chromatography (GPC). Experiments were performed on samples of poly(vinyl chloride) (PVC) and high-cis polybutadiene polymers. Osmotic data were obtained in the usual manner, while GPC data were obtained using the universal calibration approach. It was found that when all polymer species below approximately 10,000 molecular weight were excluded from the calculation of M?n by GPC, agreement in M?n was obtained between membrane osmometry and GPC. The data obtained suggest that the choice of M?n as measured by membrane osmometry in the calibration of the GPC should not be done casually, as the measured M?n may not reflect the “true” value of that sample, especially when the polymer sample contains an appreciable amount of low molecular weight material. 相似文献
4.
Máté Matolcsi 《Acta Mathematica Hungarica》2005,108(1-2):129-136
Summary He present work deals with estimations of the n-th linear polarization constant c(H)n of an n-dimensional real Hilbert space H. We provide some new lower bounds on the value of sup║y║=1 │1,y> ... n,y>│, where x1, ... ,xn are unit vectors in H. In particular, the results improve an earlier estimate of Marcus. However, the intriguing conjecture c(H) n= nn/2 remains open. 相似文献
5.
Mate Wierdl 《Israel Journal of Mathematics》1988,64(3):315-336
The pointwise ergodic theorem is proved for prime powers for functions inL
p,p>1. This extends a result of Bourgain where he proved a similar theorem forp>(1+√3)/2.
This paper is a part of the author’s Ph.D. thesis supervised by V. Bergelson. 相似文献
6.
Spacetime structures defined in the language of manifolds admit an absolute formulation, i.e., a formulation which does not refer to observers (reference frames). We consider an affine structure for Galilean spacetime. As an application the Chapman-Enskog iteration for the solution of the Boltzmann equation is given in an absolute form. As a consequence, the second approximations of the stress tensor and the heat flux are obtained in a form independent of observers, which throws new light on material frame indifference. 相似文献
7.
8.
T. Matolcsi 《Foundations of Physics》1998,28(11):1685-1701
Nonstandard synchronizations of inertial observers in special relativity and synchronizations with respect to a uniformly rotating observer are investigated in a setting which avoids coordinates and transformation rules and so removes some misunderstandings. 相似文献
9.
10.
Balint Farkas Mate Matolcsi Peter Mora 《Journal of Fourier Analysis and Applications》2006,12(5):483-494
Recent methods developed by Tao [18], Kolountzakis and Matolcsi [7] have led to counterexamples to Fugelde’s Spectral Set
Conjecture in both directions. Namely, in
Tao produced a spectral set which is not a tile, while Kolountzakis and Matolcsi showed an example of a nonspectral tile.
In search of lower dimensional nonspectral tiles we were led to investigate the Universal Spectrum Conjecture (USC) of Lagarias
and Wang [14]. In particular, we prove here that the USC and the "tile → spectral" direction of Fuglede’s conjecture are equivalent
in any dimensions. Also, we show by an example that the sufficient condition of Lagarias and Szabó [13] for the existence
of universal spectra is not necessary. This fact causes considerable difficulties in producing lower dimensional examples
of tiles which have no spectra. We overcome these difficulties by invoking some ideas of Révész and Farkas [2], and obtain
nonspectral tiles in
. Fuglede’s conjecture and the Universal Spectrum Conjecture remains open in 1 and 2 dimensions. The one-dimensional case
is closely related to a number theoretical conjecture on tilings by Coven and Meyerowitz [1]. 相似文献