Traveltime and amplitude calculation using a perturbation approach

An Amplitude and Traveltime Calculation Using a Higher-order Parabolic Equation

A higher-order parabolic equation is used to compute the traveltime (phase) and the amplitude in constant density acoustic media. This approach is in the frequency domain, thereby avoiding the high frequency approximation inherent in the Eikonal equation. Intrinsic attenuation can be naturally incorporated into the calculation. The error at large angles of propagation caused by the expansion of...

Gradient Calculation of the Traveltime Cost

Computing traveltime and amplitude sensitivity kernels in finite-frequency tomography

The efficient computation of finite-frequency traveltime and amplitude sensitivity kernels for velocity and attenuation perturbations in global seismic tomography poses problems both of numerical precision and of validity of the paraxial approximation used. We investigate these aspects, using a local model parameterization in the form of a tetrahedral grid with linear interpolation in between g...

Automatic traveltime picking using the instantaneous traveltime a

Event picking is used in many steps of seismic processing. We present an automatic event picking method that is based on a new attribute of seismic signals, the instantaneous traveltime. The calculation of the instantaneous traveltime consists of two separate but interrelated stages. First, a trace is mapped onto the time-frequency domain. Then the time-frequency representation is mapped back o...

A Novel Reference Current Calculation Method for Shunt Active Power Filters using a Recursive Algebraic Approach

This paper presents a novel method to calculate the reference source current and the referencecompensating current for shunt active power filters (SAPFs). This method first calculates theamplitude and phase of the fundamental load current from a recursive algebraic approach blockbefore calculating the displacement power factor. Next, the amplitude of the reference mains currentis computed with ...