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61.
Part 1 of this paper gave the derivation of basic formulae for the Ronchi test, treated as a form of wavefront shearing interferometer. In Part 2, practical, easy-to-apply versions of these formulae are given together with instructions for their use, and some experimental verifications of the formulae are described. 相似文献
62.
Let pm be any prime power and Kn(a,pm) be the Kloosterman sum , where the xi are restricted to values not divisible by p. Let m,n be positive integers with m?2 and suppose that pγ||(n+1). We obtain the upper bound , for odd p. For p=2 we obtain the same bound, with an extra factor of 2 inserted. 相似文献
63.
Hannu?TiitinenEmail author Anna?Mari?M?kel? Ville?M?kinen Patrick?JC?May Paavo?Alku 《BMC neuroscience》2005,6(1):62
Background
The cortical activity underlying the perception of vowel identity has typically been addressed by manipulating the first and second formant frequency (F1 & F2) of the speech stimuli. These two values, originating from articulation, are already sufficient for the phonetic characterization of vowel category. In the present study, we investigated how the spectral cues caused by articulation are reflected in cortical speech processing when combined with phonation, the other major part of speech production manifested as the fundamental frequency (F0) and its harmonic integer multiples. To study the combined effects of articulation and phonation we presented vowels with either high (/a/) or low (/u/) formant frequencies which were driven by three different types of excitation: a natural periodic pulseform reflecting the vibration of the vocal folds, an aperiodic noise excitation, or a tonal waveform. The auditory N1m response was recorded with whole-head magnetoencephalography (MEG) from ten human subjects in order to resolve whether brain events reflecting articulation and phonation are specific to the left or right hemisphere of the human brain. 相似文献64.
In a recent paper we used a phase-field model of solidification in deeply undercooled pure melts to show that a kinetic instability could result in dendrite tip splitting, and we speculated that such tip splitting could give rise to the phenomenon of spontaneous grain refinement. Here we present evidence, from the as-solidified microstructure of deeply undercooled ultrahigh purity Cu, of what appears to be dendrite tip splitting during recalescence. The significance of this finding in a nongrain refined sample is discussed in terms of the current theories for spontaneous grain refinement. 相似文献
65.
A. Bensaada R. W. Cochrane R. A. Masut R. Leonelli G. Kajrys 《Journal of Crystal Growth》1993,130(3-4):433-443
We examine the relation between surface morphology and lattice distortions of a number of GaxIn1-xP epilayers (x ≈ 0.04) grown on InP (001) substrates using atomic force microscopy (AFM) and high resolution X-ray diffractometry (HRXRD). The heteroepitaxial layers (thickness ≈ μm) were grown by low pressure metalorganic vapour phase epitaxy (MOVPE) at temperatures from 600 to 660°C. AFM images over a scale of 75 μm by 75 μm show no surface corrugations for samples grown at 640°C. For other growth temperatures between 600 and 660°C, unidirectional corrugations aligned along the [1
0] direction or a cross-hatched pattern can be seen on the sample surfaces with a typical interline separation of 10 μm. Another feature revealed by AFM is the presence, for some samples, of weak parallel corrugations along the direction making a 54° angle with the [1
0] direction. HRXRD spectra recorded first with the [110] and then with the [1
0] direction in the plane of incidence reveal an asymmetric relaxation in the sample plane accompanied by a broadening of the epilayer X-ray peak for diffraction with the [110] direction in the plane of incidence. The lattice distortion changes from tetragonal to orthorhombic as the surface corrugations appear along the [1
0] direction. Proton microprobe scans indicate that these samples are compositionally uniform so that the asymmetry is not the result of lateral variations of the alloy composition. Finally, low temperature photoluminescence from these samples shows good agreement between observed and calculated peak positions on the basis of the strains obtained from HRXRD measurements. 相似文献
66.
Blewitt G LoSecco JM Bionta RM Bratton CB Casper D Chrysicopoulou P Claus R Cortez BG Errede S Foster GW Gajewski W Ganezer KS Goldhaber M Haines TJ Jones TW Kielczewska D Kropp WR Learned JG Lehmann E Park HS Reines F Schultz J Seidel S Shumard E Sinclair D Sobel HW Stone JL Sulak L Svoboda R van der Velde JC Wuest C 《Physical review letters》1985,55(20):2114-2117
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