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141.
We improve an upper bound for the chromatic index of a multigraph due to Andersen and Gol'dberg. As a corollary we deduce that if no two edges of multiplicity at least two in G are adjacent, then χ′(G) ? Δ(G) + 1. In addition we generalize results concerning the structure of critical graphs due to Vizing and to Chetwynd and Hilton. 相似文献
142.
T. Dumelow A. A. Hamilton T. J. Parker D. R. Tilley C. T. B. Foxon D. Hilton K. J. Moore 《International Journal of Infrared and Millimeter Waves》1990,11(8):901-917
We have used far-infrared oblique-incidence reflection spectroscopy to study bulk phonon polaritons, and attenuated total reflection (ATR) spectroscopy to study surface phonon polaritons, in long-period GaAs/AlxGa1–xAs and short-period GaAs/AlAs superlattices. Results on the former are in good agreement with an effective-medium bulk-slab model of the dielectric tensor of the superlattice; results on the latter are analysed in terms of a model that contains dielectric-tensor contributions from the confined optic phonons. 相似文献
143.
A pair of doubly diagonal orthogonal latin squares of order n, DDOLS(n), is a pair of orthogonal latin squares of order n with the property that each square has a transversal on both the front diagonal (the cells {(i, i):1?i?n}) and the back diagonal (the cells {(i, n + 1?i): 1?i?n}). We show that for all n except n = 2, 3, 6, 10, 12, 14, 15, 18 and 26, there exists a pair of DDOLS(n). Obbviously these do not exist when n = 2, 3 and 6. 相似文献
144.
A.J.W Hilton 《Journal of Combinatorial Theory, Series B》1984,36(2):125-134
It is well known that K2n + 1 can be decomposed into n edge-disjoint Hamilton cycles. A novel method for constructing Hamiltonian decompositions of K2n + 1 is given and a procedure for obtaining all Hamiltonian decompositions of of K2n + 1 is outlined. This method is applied to find a necessary and sufficient condition for a decomposition of the edge set of Kr (r ≤ 2n) into n classes, each class consisting of disjoint paths to be extendible to a Hamiltonian decomposition of K2n + 1 so that each of the classes forms part of a Hamilton cycle. 相似文献
145.
146.
High-average-power Nd:YAG planar waveguide laser that is face pumped by 10 laser diode bars 总被引:2,自引:0,他引:2
A planar waveguide Nd:YAG laser is pumped with 430 W of power from 10 laser diode bars to produce a multimode output power of 150 W at an optical efficiency of 35%. Use of a hybrid resonator of the positive-branch confocal unstable type for the lateral axis and of one of the near-case I waveguide type for the transverse axis increased the laser brightness by a factor of ~26 with only 12% less power than in the multimode case. 相似文献
147.
Optical orientation of spin-polarized heavy and light holes followed by relaxation to other valence subband states has been observed unambiguously in undoped bulk GaAs in spite of the extremely short spin relaxation time. The measured relaxation time for the heavy holes is 110 fs +/-10%. The results are relevant for applications such as interpretation of spin-polarized transport in semiconductors as well as the assessment of feasibility of hole-based spin-transport devices which relies on precise knowledge of the hole-spin relaxation time. 相似文献
148.
149.
David Wilbur Wayne B. Manning Bruce D. Hilton Gary M. Muschik 《Magnetic resonance in chemistry : MRC》1982,18(2):63-67
Benz[a]anthracene-7, 12-dione, eight monomethoxybenz[a]anthracene-7, 12-diones and two dimethoxybenz[a]anthracene-7, 12-diones were analyzed by 13C and 1H NMR. All 13C and 1H resonances have been assigned. Substituent effects on the 13C chemical shifts are discussed. 相似文献
150.
We demonstrate that emission-induced self-organization of two-level atoms can effect strong damping of the sample's center-of-mass motion. When illuminated by far-detuned light, cold cesium atoms assemble into a density grating that efficiently diffracts the incident light into an optical resonator. We observe random phase jumps of pi in the emitted light, confirming spontaneous symmetry breaking in the atomic self-organization. The Bragg diffraction results in a collective friction force with center-of-mass deceleration up to 1000 m/s(2) that is effective even for an open atomic transition. 相似文献