304 research outputs found
Stochastic Thermodynamics of oscillators networks
We apply the stochastic thermodynamics formalism to describe the dynamics of
systems of complex Langevin and Fokker-Planck equations. We provide in
particular a simple and general recipe to calculate thermodynamical currents,
dissipated and propagating heat for networks of nonlinear oscillators. By using
the Hodge decomposition of thermodynamical forces and fluxes, we derive a
formula for entropy production that generalises the notion of non-potential
forces and makes trans- parent the breaking of detailed balance and of time
reversal symmetry for states arbitrarily far from equilibrium. Our formalism is
then applied to describe the off-equilibrium thermodynamics of a few examples,
notably a continuum ferromagnet, a network of classical spin-oscillators and
the Frenkel-Kontorova model of nano friction.Comment: 8 pages, 1 figur
Multiscale approach to spin transport in magnetic multilayers
This article discusses two dual approaches to spin transport in magnetic
multilayers: a direct, purely quantum, approach based on a Tight-Biding model
(TB) and a semiclassical approach (Continuous Random Matrix Theory, CRMT). The
combination of both approaches provides a systematic way to perform
multi-scales simulations of systems that contain relevant physics at scales
larger (spin accumulation, spin diffusion...) and smaller (specular reflexions,
tunneling...) than the elastic mean free paths of the layers. We show
explicitly that CRMT and TB give consistent results in their common domain of
applicability
A Scalable VLSI Architecture for Soft-Input Soft-Output Depth-First Sphere Decoding
Multiple-input multiple-output (MIMO) wireless transmission imposes huge
challenges on the design of efficient hardware architectures for iterative
receivers. A major challenge is soft-input soft-output (SISO) MIMO demapping,
often approached by sphere decoding (SD). In this paper, we introduce the - to
our best knowledge - first VLSI architecture for SISO SD applying a single
tree-search approach. Compared with a soft-output-only base architecture
similar to the one proposed by Studer et al. in IEEE J-SAC 2008, the
architectural modifications for soft input still allow a one-node-per-cycle
execution. For a 4x4 16-QAM system, the area increases by 57% and the operating
frequency degrades by 34% only.Comment: Accepted for IEEE Transactions on Circuits and Systems II Express
Briefs, May 2010. This draft from April 2010 will not be updated any more.
Please refer to IEEE Xplore for the final version. *) The final publication
will appear with the modified title "A Scalable VLSI Architecture for
Soft-Input Soft-Output Single Tree-Search Sphere Decoding
- …