31,602 research outputs found
A new Lagrangian method for time-dependent inviscid flow computation
No full textThis paper presents a new Lagrangian approach for the two-dimensional (2-D) time-dependent Euler equations. It may be considered as a sequel to the authors' previous Lagrangian approaches for steady supersonic flow computations [C. Y. Loh and W. H. Hui, J. Comput. Phys., 89 (1990), pp. 207-240; W. H. Hui and C. Y. Loh, J. Comput. Phys., 103 (1992), pp. 450-464; W. H. Hui and C. Y. Loh, J. Comput. Phys., 103 (1992), pp. 465-471; C. Y. Loh and M. S. Liou, J. Comput. Phys., 104 (1993), pp. 150-161; C. Y. Loh and M. S. Liou, SIAM J. Sci. Comput., 15 (1994), pp. 1038-1058; C. Y. Loh and M. S. Liou, J. Comput. Phys., 113 (1994), pp. 224-248]. The theoretical background and the intrinsic flow coordinates as well as the Lagrangian conservation form are introduced based on the concept of material functions (or path functions). A TVD scheme of the Godunov type is chosen to describe the numerical procedure. Several examples are then given to justify the claimed advantages of the new methodology, namely, (a) any contact discontinuities are crisply solved and (b) grids are automatically and accurately generated following pathlines.</p
1.06 µm picosecond pulsed, normal dispersion pumping for generating efficient broadband infrared supercontinuum in meter-length single-mode tellurite holey fiber with high Raman gain coefficient
No full textWe investigate efficient broadband infrared supercontinuum generation in meter-length single-mode small-core tellurite holey fiber. The fiber is pumped by 1.06µm picosecond pulses in the normal dispersion region. The high Raman gain coefficient and the broad Raman gain bands of the tellurite glass are exploited to generate a cascade of Raman Stokes orders, which initiate in the highly normal dispersion region and quickly extend to longer wavelengths across the zero dispersion wavelength with increasing pump power. A broadband supercontinuum from 1.06µm to beyond 1.70µm is generated. The effects of the pump power and of the fiber length on the spectrum and on the power conversion efficiency from the pump to the supercontinuum are discussed. Power scaling indicates that using this viable normal dispersion pumping scheme, 9.5 W average output power of infrared supercontinuum and more than 60% conversion efficiency can be obtained from a 1 m long tellurite fiber with a large mode area of 500µm2
Application of horizontal-to-vertical (H/V)Fourier spectra ratio for analysis of site effect on rock (NEHRB-Class B) sites in Taiwan
No full textW-type highly erbium-doped active soft-glass fiber with high nonlinearity
No full textA highly nonlinear W-type erbium-doped fibre with high dopant concentration made of three lead silicate glass materials (Schott SF57, LLF1 and SF6) is presented. The fibre is designed to have a flat anomalous dispersion at ~1.55 µm, which is critical for enhancing parametric wavelength conversion. With this fibre, signals at ~ 1.55 µm are successfully amplified in continuous-wave and pico-second-pulsed formats with a 1.48 µm pump source. In particular, spectral broadening of over 350 nm together with strong degenerate four-wave-mixing effects is demonstrated. The authors highlight that this novel fibre combines, for first time to their knowledge, the benefits of highly doped active fibres with those of dispersion/nonlinearity-engineered fibres
Effects of hysteretic model on seismic demands: consideration of near-fault ground motions
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