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31.
An overview of theoretical and experimental studies of the coherent type-B e
+
e-pair production by photons in aligned crystals performed at Nuclear Physics Institute at Tomsk Polytechnic University is given. 相似文献
32.
We calculate the leading and next-to-leading logarithmic resummed distribution for the jet broadening in deep inelastic scattering,
as well as the power correction for both the distribution and mean value. A truncation of the answer at NLL accuracy, as is
standard, leads to unphysical divergences. We discuss their origin and show how the problem can be resolved. We then examine
DIS specific procedures for matching to fixed order calculations and compare our results to the data. One of the tools developed
for the comparison is an NLO parton distribution evolution code. When compared to PDF sets from MRST and CTEQ it reveals limited
discrepancies in both.
Received: 16 October 2001 / Published online: 12 April 2002 相似文献
33.
34.
It is proved that biorthogonal polynomials obey two different kinds of Christoffel-Darboux-type formulae, one linking polynomials with a different parameter and one combining polynomials with different degrees. This is used to produce a mixed recurrence relation, which is valid for all biorthogonal polynomials. This recurrence relation establishes several results on interlacing property of zeros of successive biorthogonal polynomials and leads to a new result on the interlace of zeros of orthogonal polynomials (of equal degrees) with respect to two distributionsdψ(x) andx p dψ(x), 0<p≤1, with support in either [0, 1] or [1, ∞). 相似文献
35.
36.
We establish sufficient conditions for the existence and uniqueness of a periodic solution of a system of linear differential equations with a small parameter and a degenerate matrix of coefficients of derivatives in the case of a multiple spectrum of a boundary matrix pencil. We construct asymptotics of this solution. 相似文献
37.
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39.
P. Adamson 《Optics & Laser Technology》2002,34(7):561-568
The differential reflection characteristics for ultrathin inhomogeneous dielectric film on absorbing substrate are investigated in the long-wavelength approximation. The obtained first-order expressions for differential reflectivity and changes in the ellipsometric angles caused by ultrathin layer are of immediate interest to the solution of the inverse problem. The method to determine the averaged values (not the realistic profile) of refractive index for inhomogeneous nanometric films are shown. The novel possibilities for determining the dielectric constant and thickness of nanoscale homogeneous films by the differential ellipsometric and reflectivity measurements are developed, and a simple method to estimate whether the nanometric film is homogeneous or not is also discussed. 相似文献
40.
A comprehensive study of the long pulse Nd:YAG laser drilling of multi-layer carbon fibre composites 总被引:2,自引:0,他引:2
W. S. O. Rodden S. S. Kudesia D. P. Hand J. D. C. Jones 《Optics Communications》2002,210(3-6):319-328
The results of an extensive experimental study of the free running Nd:YAG laser drilling of a multi-layer carbon fibre composite, where adjacent layers have differently orientated fibres, are reported. For holes drilled with the laser operating in fixed-Q mode at 1064 nm, parallel sections of blind holes illustrating discontinuities in the hole size along a given section direction will be shown to occur at the interface between adjacent layers. An explanation for this effect is proposed. Detailed single pulse drilling characteristics will be presented illustrating the exit hole diameter as a function of pulse energy and material thickness. These characteristics illustrate a ‘stable' drilling regime in which the exit hole diameters are least sensitive to changes in pulse energy or material thickness and a less ‘stable' regime in which they are more strongly dependent on these parameters. Drilling characteristics will be given for two different beam qualities, illustrating the greater drilling depth and reduced hole size achievable with an improved beam quality. Finally holes drilled through a 2 mm thick sample of material with multiple pulses are considered. Size distribution curves for entrance and exit holes will be presented. The total energy required (number of pulses × pulse energy) to drill through 2 mm thick material will be reported as a function of pulse energy in stationary air and argon atmospheres and in a partial vacuum, illustrating a threshold energy which is dependent upon the drilling atmosphere. The threshold energies will be discussed with reference to plasma formation and the reactivity of the drilling atmosphere. 相似文献