16,873 research outputs found
Lattice-gas modeling of CO adlayers on Pd(100)
Using a lattice-gas model with pairwise interactions, we study the ordered
structures, coverage dependence of the heat of adsorption, and other
experimentally observable behavior of adsorbed CO overlayers on Pd(100) single
crystal surfaces. Transfer matrix and Monte Carlo methods give accurate
information regarding the lattice-gas model that often contradicts simple
mean-field-like analysis. We demonstrate the usefulness of the model by
reproducing experimental results over a large range of pressures and
temperatures.Comment: 6 pages, 5 figure
Spectral Efficiency Analysis of Multi-Cell Massive MIMO Systems with Ricean Fading
This paper investigates the spectral efficiency of multi-cell massive
multiple-input multiple-output systems with Ricean fading that utilize the
linear maximal-ratio combining detector. We firstly present closed-form
expressions for the effective signal-to-interference-plus-noise ratio (SINR)
with the least squares and minimum mean squared error (MMSE) estimation
methods, respectively, which apply for any number of base-station antennas
and any Ricean -factor. Also, the obtained results can be particularized in
Rayleigh fading conditions when the Ricean -factor is equal to zero. In the
following, novel exact asymptotic expressions of the effective SINR are derived
in the high and high Ricean -factor regimes. The corresponding analysis
shows that pilot contamination is removed by the MMSE estimator when we
consider both infinite and infinite Ricean -factor, while the pilot
contamination phenomenon persists for the rest of cases. All the theoretical
results are verified via Monte-Carlo simulations.Comment: 15 pages, 2 figures, the tenth International Conference on Wireless
Communications and Signal Processing (WCSP 2018), to appea
Symmetry-Breaking and Percolation Transitions in a Surface Reaction Model with Superlattice Ordering
A symmetry-breaking order-disorder transition of the Ising type is found in a nonequilibrium surface reaction model for CO oxidation incorporating superlattice ordering of adsorbed oxygen. We relate this transition to the percolation of superlattice domains of oxygen, and discuss the consequences for chemical diffusion of coadsorbed CO. The latter constitutes a new type of problem involving transport in disordered media
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