The helicopter-borne electromagnetic (HEM) frequency-domain exploration method is an airborne electromagnetic (AEM) technique that is widely used for vast and rough areas for resistivity imaging. The vast amount of digitized data flowing from the HEM method requires an efficient and accurate inversion algorithm. Generally, the inverse modelling of HEM data in the first step requires a precise a...

The computation of solution paths for continuation problems requires the solution of a sequence of nonlinear systems of equations. Each nonlinear system can be solved by computing the solution of a succession of linear systems of equations determined by Jacobian matrices associated with the nonlinear system of equations. Points on the solution path where the Jacobian matrix is singular are refe...

We present a geometric construction of Bäcklund transformations and discretizations for a large class of algebraic completely integrable systems. To be more precise, we construct families of Bäcklund transformations, which are naturally parametrized by the points on the spectral curve(s) of the system. The key idea is that a point on the curve determines, through the Abel-Jacobi map, a vector o...

This paper presents an attempt to generalize the computation of the simplest normal form of differential equations. The study is focused on the systems whose Jacobian evaluated at an equilibrium has 1:2 resonant double Hopf singularity. After obtaining the general conventional (classical) normal form, we have constructed the simplest normal form for the 1:2 resonance and proved that the pattern...

In this paper the high-order accurate spectral difference method for the Navier-Stokes equations is applied to moving boundary problems. Boundary movements are achieved, firstly, through rigid displacement of the entire flow domain. In order to account for the dynamic rigid mesh motion, the Navier-Stokes equations are modified through an unsteady coordinate transformation. Airfoils in pitching ...