Hybrid ensemble–three-dimensional variational analysis schemes incorporate flow-dependent, ensembleestimated background-error covariances into the three-dimensional variational data assimilation (3DVAR) framework. Typically the 3DVAR background-error covariance estimate is assumed to be stationary, nearly homogeneous, and isotropic. A hybrid scheme can be achieved by 1) directly replacing the b...

In the past few years new methods have been proposed that can be seen as combinations of standard Krylov subspave methods, such as Bi{ CG and GMRES. One of the rst hybrid schemes of this type is CGS, actually the Bi{CG squared method. Other such hybrid schemes include BiCGSTAB (a combination of Bi{CG and GMRES(1)), QMRS, TFQMR, Hybrid GMRES (polynomial preconditioned GMRES) and the nested GMRES...

In numerical modeling of physical phenomena it is often necessary to solve the advective transport equation for positive definite scalar functions. Numerical schemes of secondor higher-order accuracy can produce negative values in the solution due to the dispersive ripples. Lower-order schemes, such as the donor cell or Lax-Friedrichs, or higher-order schemes with zeroth-order diffusion added p...

This paper proposes noncoherent PN acquisition schemes that combine the hybrid structure, the RAKE structure, and the double/multiple-dwell technique in order to improve the performance in a frequency-selective fading channel. The hybrid structure reduces the acquisition time compared to a serial scheme. The RAKE structure enhances the received signal strength of a multipath faded signal, while...

Error detection plays an important role in fault-tolerant computer systems. Two primary parameters concerned for error detection are the latency and coverage. In this paper, a new, hybrid error-detection approach offering a very high coverage with no detection latency is proposed to protect the data paths of high-performance microprocessors. The feature of no detection latency is essential to r...

A heuristic particle swarm optimization (PSO) based algorithm is presented in this work and the novel hybrid approach is applied to linear array synthesis considering complex weights and directive element patterns so as to analyze its usefulness and limitations. Basically, classical PSO schemes are modified by introducing a tournament selection strategy and the downhill simplex local search met...

Estimating the state of a hybrid system means accounting for the mode of operation or failure and the current state of the continuously valued entities concurrently. Existing hybrid estimation schemes try to overcome the problem of an exponentially growing number of possible mode-sequence/continuous-state combinations by merging hypotheses and/or deducing likelihood measures to identify tractab...

The main idea of highly accurate multioperators schemes for CFD applications is briefly outlined, their optimization being discussed.. Several examples of numerical simulations related to aeroacoustics are presented. Hybrid schemes with multioperators for shock capturing calculations are considered.

To minimize total transmit power in a system while guaranteeing the outage probability at the same time in a cooperative system, we propose and analyse two threshold-based hybrid relay selection and power allocation schemes for a threenode cooperative relaying system. They are designated as: the hybrid amplify-direct-forward relaying (HADF) and incremental hybrid decode-direct-forward relaying ...