A new numerical method for approximating highly oscillatory wave fields as a superposition of Gaussian beams is presented. The method estimates the number of beams and their parameters automatically. This is achieved by an expectation-maximization algorithm that fits real, positive Gaussians to the energy of the highly oscillatory wave fields and its Fourier transform. Beam parameters are furth...

Oscillatory integrals over fan-shaped regions widely exist in scattering analysis, and this paper proposes a new rapid calculation routine for them. In the routine, the concerned bivariate scattering oscillatory integral is reduced to the calculation of two univariate oscillatory integrals. One is calculated with the improved Levin quadrature method, and another is transformed to a non-oscillat...

Multiple biological processes are driven by oscillatory gene expression at different time scales. Pulsatile dynamics are thought to be widespread, and single-cell live imaging of gene expression has lead to a surge of dynamic, possibly oscillatory, data for different gene networks. However, the regulation of gene expression at the level of an individual cell involves reactions between finite nu...

This paper introduces a non-oscillatory method, the finite element flux-corrected transport (FE-FCT) method for spallation studies. This method includes the implementation of a one-dimensional FCT algorithm into a total Lagrangian finite element method. Consequently, the FE-FCT method can efficiently eliminate fluctuations behind shock wave fronts without smearing them. In multidimensional simu...

Oscillatory pumping tests-in which flow is varied in a periodic fashion-provide a method for understanding aquifer heterogeneity that is complementary to strategies such as slug testing and constant-rate pumping tests. During oscillatory testing, pressure data collected at non-pumping wells can be processed to extract metrics, such as signal amplitude and phase lag, from a time series. These me...

Recently the author has given two modifications of a nonlinear extrapolation method due to Levin and Sidi, which enable one to accurately and economically compute certain infinite integrals whose integrands have a simple oscillatory behavior at infinity. In this work these modifications are extended to cover the case of very oscillatory infinite integrals whose integrands have a complicated and...