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71.
72.
A theoretical investigation has been carried out on the effect of a drift current on surface polaritons in n-type silicon. The current direction is taken to be parallel to the direction of propagation of the surface polaritons. From the dispersion curves, there is evidence that an interaction takes place between the current and the polaritons which gives rise to polariton instability or amplification for certain frequency ranges. These instabilities are believed to be due to the presence of the surface. 相似文献
73.
74.
Jennifer Seberry Wallis 《Journal of Combinatorial Theory, Series A》1976,21(2):188-195
Given any natural number q > 3 we show there exists an integer t ? [2log2(q ? 3)] such that an Hadamard matrix exists for every order 2sq where s > t. The Hadamard conjecture is that s = 2.This means that for each q there is a finite number of orders 2υq for which an Hadamard matrix is not known. This is the first time such a statement could be made for arbitrary q.In particular it is already known that an Hadamard matrix exists for each 2sq where if q = 2m ? 1 then s ? m, if q = 2m + 3 (a prime power) then s ? m, if q = 2m + 1 (a prime power) then s ? m + 1.It is also shown that all orthogonal designs of types (a, b, m ? a ? b) and (a, b), 0 ? a + b ? m, exist in orders m = 2t and 2t+2 · 3, t ? 1 a positive integer. 相似文献
75.
The dispersion curves for surface plasma waves (SPW) in Ag have been determined from calculated reflectivity minima as exhibited by attenuated total reflection (ATR spectra) for the prism-air-metal (PAM) configuration and from the direct calculation of the dispersion relation for the same configuration. The dispersion curves for Au have been determined by measuring the ATR spectra for the prism-dielectric-metal (PDM) configuration, by calculating the ATR spectra from published optical constants and from the direct calculation of the despersion relation for the PDM configuration. We have found two general types of solutions from the direct calculation of the dispersion relation for both configurations. The two solutions are the surface or Brewster modes and the virtual modes. The characteristics of both modes are discussed. The effect of electronic damping upon the dispersion curves for Ag which exhibits low electronic damping and Au which exhibits moderate electronic damping is demonstrated. Finally the perturbing effect of the dielectric (referred herein as dielectric shift) upon the displacement of the dispersion curves to higher wave number for the PAM configuration for Ag and for the PDM configuration for Au is shown. 相似文献
76.
The collisionsless Boltzmann equation is solved in two ways by the method of characteristics. The solution is used for an exact treatment of higher-order temporal and spatial plasma wave echoes in the absence of steady external fields. The second-order spatial echo is treated separately and analyzed numerically. 相似文献
77.
Methods of Intermediate Problems for Eigenvalues: Theory and Ramifications, by Alexander Weinstein and William Stenger. Academic Press, 1971. ($16.00)
Combinatorics, Proceedings of the British Combinatorial Conference 1973, Edited by T.P. McDnough and V.C. Mavron, London Mathematical Society Lecture Note Series 13, Cambridge University Press, London, New York, 1974. 204pp.($9.95) 相似文献
Combinatorics, Proceedings of the British Combinatorial Conference 1973, Edited by T.P. McDnough and V.C. Mavron, London Mathematical Society Lecture Note Series 13, Cambridge University Press, London, New York, 1974. 204pp.($9.95) 相似文献
78.
W.D Wallis 《Journal of Combinatorial Theory, Series A》1973,15(3):329-332
Suppose there is a Room square of side r. Then there is a Room square of side 4r + 1 with a sub-square of side r which is isomorphic to the original square.No example was known previously of a Room square of side s with a subsquare of side r where s ? 6r. 相似文献
79.
Lee D. Hall Guy Orpen Melanie Pilkington John. D. Wallis 《Journal of chemical crystallography》2001,31(2):97-103
2-Phenylethynylbenzoic acid shows a short intramolecular 1,5 C=O···spC contact with no significant in-plane distortion of bonding geometry at the sp C atom. However, there are angular distortions at the second sp C atom and the adjacent ipso C atom of the benzene ring, most likely because of optimization of the packing arrangement. Crystal data: C15H10O2, Mr = 222.23, a = 6.1890(10), b = 9.791(2), c = 18.849(4) Å, = 97.14(2)°, monoclinic, P21/n, Z = 4. 相似文献
80.