We present and analyze a class of nonsymmetric preconditioners within a normal (weighted least-squares) matrix form for use in GMRES to solve nonsymmetric matrix problems that typically arise in finite element discretizations. An example of the additive Schwarz method applied to nonsymmetric but definite matrices is presented for which the abstract assumptions are verified. A variable precondit...

Mobile OFDM refers to OFDM systems with fast moving transceivers, in contrast to traditional OFDM systems whose transceivers are stationary or have a low velocity. In this paper, we use the basis expansion model (BEM) to model time-varying OFDM channels. Using different BEM’s, we investigate various architectures to implement the least-squares (LS) channel estimation and its corresponding zero-...

In this paper we analyze several first-order systems of Oseen-type equations that are obtained from the time-dependent incompressible NavierStokes equations after introducing the additional vorticity and possibly total pressure variables, time-discretizing the time derivative and linearizing the nonlinear terms. We apply the [L, L, L] least-squares finite element scheme to approximate the solut...