We present a Newton-CG method for full-waveform seismic inversion. Our method comprises the adjoint-based computation of the gradient and Hessianvector products of the reduced problem and a preconditioned conjugate gradient method to solve the Newton system in matrix-free fashion. A trust-region globalization strategy and a multi-frequency inversion approach are applied. The governing equations...

A Newton–Krylov method is an implementation of Newton’s method in which a Krylov subspace method is used to solve approximately the linear subproblems that determine Newton steps. To enhance robustness when good initial approximate solutions are not available, these methods are usually globalized, i.e., augmented with auxiliary procedures (globalizations) that improve the likelihood of converge...

A fast Newton-Krylov algorithm is presented for solving the compressible Navier-Stokes equations on structured multi-block grids with application to turbulent aerodynamic flows. The oneequation Spalart-Allmaras model is used to provide the turbulent viscosity. The optimization of the algorithm is discussed. ILU(4) is suggested for a preconditioner, operating on a modified Jacobian matrix. An ef...

A fast Newton-Krylov algorithm is presented for solving the compressible Navier-Stokes equations on structured multi-block grids with application to turbulent aerodynamic flows. The oneequation Spalart-Allmaras model is used to provide the turbulent viscosity. The optimization of the algorithm is discussed. ILU(4) is suggested for a preconditioner, operating on a modified Jacobian matrix. An ef...

In this paper we investigate some fully coupled parallel two-grid Lagrange-Newton-Krylov-Schwarz (LNKSz) algorithms for the suboptimal distributed control of unsteady incompressible flows governed by the Navier-Stokes equations. The algorithms include two major parts: a two-grid Newton method for the nonlinear part of the problem and a two-level Schwarz preconditioner for the linear part of the...

We present X-ray spectra of the nucleus of the nearby radio galaxy Centaurus A from observations with the XMM-Newton EPIC CCD cameras (two exposures separated by 12 months) and the Chandra High Energy Transmission Grating Spectrometer (HETGS). For the first time in an FRI galaxy, we resolve fluorescent Kα emission from cold, neutral, or near-neutral iron at 6.4 keV, with an r.m.s. line width of...

Quadrotor control has been noted for its trouble as the consequence of the high maneuverability, system nonlinearity and strongly coupled multivariable. This paper deals with the simulation depend on proposed controller of a quadrotor that can overcome this trouble. The mathematical model of quadrotor is determined using a Newton-Euler formulation. Fractional Order Proportional Integral Derivat...

In this article we present robust, efficient and accurate fully implicit time-stepping schemes and nonlinear solvers for systems of reaction-diffusion equations. The applications of reaction-diffusion systems is abundant in the literature, from modelling pattern formation in developmental biology to cancer research, wound healing, tissue and bone regeneration and cell motility. Therefore, it is...