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251.
252.
E. Granot S. Sternklar D. Schermann Y. Ben-Aderet M.H. Itzhaq 《Applied physics. B, Lasers and optics》2006,82(3):359-362
We use the spectral ballistic imaging technique to measure the impulse response of a Fabry–Pérot etalon with less than 0.2 ps
temporal resolution. The results show excellent agreement with the theoretical predictions and negligible noise. Comparison
to the Kramers–Kronig method along with its limitations is also presented.
PACS 42.65.Re; 07.60.Ly; 42.30.Kq 相似文献
253.
Current techniques of water wave visualization such as shadowgraphy and stereo photography are widely used but are deficient
in many aspects. Refraction based visualization observes the bending of light as it traverses across a liquid-air interface.
This work describes the continued development of techniques to measure the surface height of a liquid free surface. The method,
Reference Image Topography, utilizes refraction of light at the free surface as a function of the local angle of that surface.
Particle Image Velocimetry (PIV) software is used to evaluate apparent dislocations of the target image viewed through the
free surface, which are approximately proportional to the surface angle. High-resolution images are presented of the dynamic
surface topography for a point source and the shallow water flow around a vertical cylinder. 相似文献
254.
The black-body radiation is considered in a theory with noncommutative electromagnetic fields; that is noncommutativity is introduced in field space, rather than in real space. A direct implication of the result on cosmic microwave background map is argued. 相似文献
255.
Backstepping design is proposed for synchronization of Genesio chaotic system. Firstly, the control problem for the chaos synchronization of nominal Genesio systems without unknown parameters is considered. Next, an adaptive backstepping control law is derived to make the error signals between drive Genesio system and response Genesio system with an uncertain parameter asymptotically synchronized. Finally, the approach is extended to the synchronization problem for the system with three unknown parameters. The stability analysis in this article is proved by using a well-known Lyapunov stability theorem. Note that the approach provided here needs only a single controller to realize the synchronization. Two numerical simulations are presented to show the effectiveness of the proposed chaos synchronization scheme. 相似文献
256.
H. P. Gunnlaugsson 《Hyperfine Interactions》2006,167(1-3):851-854
The general problem of finding a distribution in hyperfine interaction parameters from experimental Mössbauer spectra is outlined. Existing methods may lack flexibility to be easily applicable to simple problems. A line shape for hyperfine parameter distributions is given, which is based on linear segments in the probability function. This method is applied in the analysis of samples containing iron in a silicate glass. 相似文献
257.
Heinz H. Bauschke 《Proceedings of the American Mathematical Society》2007,135(1):135-139
Recently, S. Reich and S. Simons provided a novel proof of the Kirszbraun-Valentine extension theorem using Fenchel duality and Fitzpatrick functions. In the same spirit, we provide a new proof of an extension result for firmly nonexpansive mappings with an optimally localized range.
258.
von Eynatten G. Ritter T. Bömmel H. E. Dransfeld K. 《Zeitschrift für Physik B Condensed Matter》1987,65(3):341-345
A new model is presented which explains well the dramatic decrease of the Mössbauer line intensities with raising temperatures for freely dispersed iron microscrystals. In contrast to other theories which consider mainly vibration to be responsible we discuss here the decrease in terms of large amplitude diffusive rotational or translational jumps of the particles. Such diffusive jumps lead — in agreement with the observation — to a strong reduction of the Mössbauer-intensity without broadening the line width in a noticeable way. The typical potential well for a diffusing particle in an equilibrium position is derived quantitatively to be 13 meV. The model might be important also for a new understanding of the dynamics of catalytic clusters either in contact with each other or with larger solid surfaces.Part of this work was supported by the DFG Sonderforschungsbereich 306, Konstanz 相似文献
259.
Tunable properties of light propagation in photonic crystal fibers filled with liquid crystals, called photonic liquid crystal
fibers (PLCFs) are presented. The propagation properties of PLCFs strongly depend on contrast between refractive indices of
the solid core (pure silica glass) and liquid crystals (LCs) filing the holes of the fiber. Due to relatively strong thermo-optical
effect, we can change the refractive index of the LC by changing its temperature. Numerical analysis of light propagation
in PLCF, based on two simulation methods, such as finite difference (FD) and multipole method (MM) is presented. The numerical
results obtained are in good agreement with our earlier experimental results presented elsewhere [1]. 相似文献
260.
We present a simplified computational scheme in order to calculate the effects of electron correlations on the energy bands of diamond and silicon. By adopting a quasiparticle picture we compute first the relaxation and polarization effects around an electron set into a conduction-band Wannier orbital. This is done by allowing the valence orbitals to relax within a self-consistent field (SCF) calculation. The diagonal matrix element of the Hamiltonian leads to a shift of the center of gravity of the conduction band while the off-diagonal matrix elements result in a small reduction of the conduction-electron bandwidth. This calculation is supplemented by the computation of the loss of ground-state correlations due to the blocked Wannier orbital into which the added electron has been placed. The same procedure applies to the removal of an electron, i.e., to the valence bands. But the latter have been calculated previously in some detail and previous results are used to estimate the energy gap in the two materials. The numerical data reported here show that the methods works, in principle, but that some extension of the scheme is also necessary to obtain fully satisfactory results.Dedicated to J.-P. Malrieu on the occasion of his 60th birthday 相似文献