Magnetotransport through an Aharonov-Bohm ring with parallel double quantum dots coupled to ferromagnetic leads

Using the Keldysh nonequilibrium Green function and equation-of-motion technique, this paper studies the magnetotransport through an Aharonov--Bohm (AB) ring with parallel double quantum dots coupled to ferromagnetic leads. It calculates the transmission probability in both the equilibrium and the nonequilibrium case, analyses the conductance and the tunnel magnetoresistance for various parameters, and obtains some new results. These results show that this system is provided with an excellent spin filtering property, and that a large tunnelling magnetoresistance and a negative tunnelling magnetoresistance can arise by adjusting relative parameters; these facts indicate that this system is a possible candidate for spin valve transistors, and has important applications in spintronics.     

Relations of intensity just noticeable difference to intensity of tonal bursts with various durations

1 IntroductionThe meajsurement of intensity Just Noticeable Difference (JND) is an important meansto explore the mechanisms of loudness coding and loudness discrimination which have beenpaid close attention to, since the idea that loudness could be quantified was first suggested byFechner. However, an unified result is not reached about the JND measurement[1]. Miller(1947)showed that ratio of intensity JND to intensity (Weber fraction) for white noise is independentof intensity (so calle…     

Scalable parallel methods for monolithic coupling in fluid–structure interaction with application to blood flow modeling

We introduce and study numerically a scalable parallel finite element solver for the simulation of blood flow in compliant arteries. The incompressible Navier–Stokes equations are used to model the fluid and coupled to an incompressible linear elastic model for the blood vessel walls. Our method features an unstructured dynamic mesh capable of modeling complicated geometries, an arbitrary Lagrangian–Eulerian framework that allows for large displacements of the moving fluid domain, monolithic coupling between the fluid and structure equations, and fully implicit time discretization. Simulations based on blood vessel geometries derived from patient-specific clinical data are performed on large supercomputers using scalable Newton–Krylov algorithms preconditioned with an overlapping restricted additive Schwarz method that preconditions the entire fluid–structure system together. The algorithm is shown to be robust and scalable for a variety of physical parameters, scaling to hundreds of processors and millions of unknowns.     

Parallel finite difference beam propagation method based on message passing interface:application to MMI couplers with two-dimensional confinement

The alternate-direction implicit finite difference beam propagation method(FD-BPM)is used to analyze the two-dimensional(2D)symmetrical multimode interference(MMI)couplers.The positions of the images at the output plane and the length of multimode waveguide are accurately determined numerically.In order to reduce calculation time,the parallel processing of the arithmetic is implemented by the message passing interface and the simulation is accomplished by eight personal computers.