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971.
972.
J.H. Adler J. Brannick C. Liu T. Manteuffel L. Zikatanov 《Journal of computational physics》2011,230(17):6647-6663
This paper develops a first-order system least-squares (FOSLS) formulation for equations of two-phase flow. The main goal is to show that this discretization, along with numerical techniques such as nested iteration, algebraic multigrid, and adaptive local refinement, can be used to solve these types of complex fluid flow problems. In addition, from an energetic variational approach, it can be shown that an important quantity to preserve in a given simulation is the energy law. We discuss the energy law and inherent structure for two-phase flow using the Allen–Cahn interface model and indicate how it is related to other complex fluid models, such as magnetohydrodynamics. Finally, we show that, using the FOSLS framework, one can still satisfy the appropriate energy law globally while using well-known numerical techniques. 相似文献
973.
O.M. Lyulin I. Morino R. Kumazawa 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(3):531-539
The absorption spectra of methane at different path lengths and different pressures for three temperatures 180, 240 and 296 K have been recorded in the 5556-6166 cm−1 region using the Bruker IFS 120 HR and 125 HR high-resolution Fourier transform spectrometers. The multispectrum fitting procedure has been applied to these spectra to recover the spectral line parameters. The main goal of this procedure was the determination of self-broadening and self-pressure-induced shift coefficients and the exponents of their temperature dependences. These parameters have been derived for 406 assigned lines with good values of the signal to noise ratio. The rotational dependence of these parameters is discussed. 相似文献
974.
When high-power annular laser beams produced by the unstable resonator pass through the volume Bragg grating (VBG), absorption of light in the VBG will induce a temperature increment, resulting in changes in surface distortion. Considering that the surface distortion of the grating induces index and period differences, the scalar wave equations for the annular laser beams propagating in the VBG have been solved numerically and iteratively using finite-difference and sparse matrix methods. The variation in intensity distributions, the total power reflection coefficient, and the power in the bucket (PIB) for the annular laser beams passing through the reflection VBG with deformation have been analyzed quantitatively. It can be shown that the surface distortion of the VBG and the beam orders of the annular beams affect evidently the intensity distributions, the power reflection coefficient, and the PIB of the output beam. The peak intensity decreases as the deformation of the VBG increases. The total power reflection efficiency decreases significantly with the increase in deformations of the VBG. The PIB of the output beam decreases as the obscuration ratio β and the deformation of the VBG increase. For the given obscuration ratio β, the influence of deformation of reflection VBG on the PIB of the annular beams is more sensitive with increase in distortion of the VBG and decrease in beam order. 相似文献
975.
F. Hajiesmaeilbaigi H. Razzaghi M. Mahdizadeh M.R.A. Moghaddam M. Ruzbehani 《Optics & Laser Technology》2011,43(8):1428-1430
In this paper, the design and the construction of a high-power side-diode-pumped Nd:YAG solid-state laser at repetition rates of 6 and 10 kHz has been presented. Second harmonic of the Nd:YAG laser with green light at 532 nm, with an average power of 111.5 W at 10 kHz repetition rate, and with 90 ns pulse duration, has been obtained by the nonlinear crystal of KTP with 59% conversion efficiency and 12% diode-to-green optical–optical efficiency in the linear resonator. Beam spot size and divergence is 4 mm and 8 mrad, respectively. The laser stability is about 97%. As a medical application of this laser, investigation of degree of effectiveness and penetration depth of laser on adenomas of resected prostate after open prostatectomy has been done. 相似文献
976.
The analytical expression for the beam propagation factor (M2-factor) of a radial Gaussian-Schell model (GSM) beam array propagating in non-Kolmogorov turbulence is derived. The influences of beam number, ring radius and generalized exponent on the M2-factor are investigated. The results indicate that the M2-factor has great dependence on the generalized exponent and the beam number. Moreover, there is an optimum ring radius, which leads to a minimum M2-factor and increases with increase in beam number. Further, the M2-factor for the superposition of the intensity is larger than that for the superposition of the cross-spectral density function (CSDF). However, the M2-factor for the superposition of the intensity is less sensitive to the turbulence than that for the superposition of the CSDF. 相似文献
977.
We present simple and accurate analytical expressions for transmission coefficient at the splice with angular offset and transverse offset in case of first higher mode propagation in graded index fibers. We employ the simple series expression for first higher order modal field for graded index fiber. The evaluation of the concerned parameters based on our formalism requires very little computations. Here, we show that our estimations match excellently well with the exact results in case of step and parabolic index fibers. Further, splice being highly tolerant for longitudinal separation, our analysis is judiciously restricted to the case of transverse and angular mismatches only. The analysis should find application in dual mode graded index fiber in all optical technology. 相似文献
978.
979.
A solid-state rotational-echo double resonance (REDOR) NMR method was introduced to identify the ?- and ψ-torsion angle from a 1H–15N or 1H–13C′ spin system of alanine-like residues in a selectively, uniformly, or extensively 15N-/13C-labeled peptide. When a Cα(i) or a 15N peak is site-specifically obtainable in the NMR spectrum of a uniformly 15N/13C-labeled sample system, the ψ- or ?-torsion angle specified by the conformational structure of peptide geometry involving 15N(i)–1Hαi–15N(i + 1) or 13C′(i − 1)–1HNi–13C′(i) spin system can be identified based on 13Cα- or 15N-detected 1Hα–15N or 1HN–13C REDOR experiment. This method will conveniently be utilized to identify major secondary motifs, such as α-helix, β-sheet, and β-turn, from a uniformly 15N-/13C-labled peptide sample system. When tested on a 13C-/15N-labeled model system of a three amino acid peptide Gly–[U–13C, 15N]Ala–[U–13C, 15N]Leu, the ψ-angle of alanine obtained experimentally, ψ = −40 ± 30°, agreed reasonably well with the X-ray determined angle, ψ = −39°. 相似文献
980.
In this paper the influence of superconducting correlations on the thermal and charge conductances in a normal metal-superconductor (NS) junction in the clean limit is studied theoretically. First we solve the quasiclassical Eilenberger equations, and using the obtained density of states we can acquire the thermal and electrical conductances for the NS junction. Then we compare the conductance in a normal region of an NS junction with that in a single layer of normal metal (N). Moreover, we study the Wiedemann-Franz (WF) law for these two cases (N and NS). From our calculations we conclude that the behaviour of the NS junction does not conform to the WF law for all temperatures. The effect of the thickness of normal metal on the thermal conductivity is also theoretically investigated in the paper. 相似文献