519 research outputs found
Quadratic integrals of motions for the systems of identical particles-quantum case
The quantum dynamical systems of identical particles admitting an additional
integral quadratic in momenta are considered. It is found that an appropriate
ordering procedure exists which allows to convert the classical integrals into
their quantum counterparts. The relation to the separation of variables in
Schroedinger equation is discussed.Comment: 6 pages, no figure
Steering effects on growth instability during step-flow growth of Cu on Cu(1,1,17)
Kinetic Monte Carlo simulation in conjunction with molecular dynamics
simulation is utilized to study the effect of the steered deposition on the
growth of Cu on Cu(1,1,17). It is found that the deposition flux becomes
inhomogeneous in step train direction and the inhomogeneity depends on the
deposition angle, when the deposition is made along that direction. Steering
effect is found to always increase the growth instability, with respect to the
case of homogeneous deposition. Further, the growth instability depends on the
deposition angle and direction, showing minimum at a certain deposition angle
off-normal to (001) terrace, and shows a strong correlation with the
inhomogeneous deposition flux. The increase of the growth instability is
ascribed to the strengthened step Erlich Schwoebel barrier effects that is
caused by the enhanced deposition flux near descending step edge due to the
steering effect.Comment: 5 page
An improved fault mitigation strategy for CUDA Fermi GPUs
High computation is a predominant requirement in many applications. In this field, Graphic Processing Units (GPUs) are more and more adopted. Low prices and high parallelism let GPUs be attractive, even in safety critical applications. Nonetheless, new methodologies must be studied and developed to increase the dependability of GPUs. This paper presents an improved fault mitigation strategy against permanent faults for CUDA Fermi GPUs. The proposed approach exploits the reverse engineering of the block scheduling policy in CUDA Fermi GPUs in order to minimize the fault mitigation timing overhead. The graceful performance degradation achieved by the proposed technique outperforms multithreaded CPU implementations and other fault mitigation strategies for CUDA GPU, even in presence of multiple permanent faults
A software-based self test of CUDA Fermi GPUs
Nowadays, Graphical Processing Units (GPUs) have become increasingly popular due to their high computational power and low prices. This makes them particularly suitable for high-performance computing applications, like data elaboration and financial computation. In these fields, high efficient test methodologies are mandatory. One of the most effective ways to detect and localize hardware faults in GPUs is a Software-Based-Self-Test methodology (SBST). In this paper a fully comprehensive SBST and fault localization methodology for GPUs is presented. This novel approach exploits different custom test strategies for each component inside the GPU architecture. Such strategies guarantee both permanent fault detection and accurate fault localization
Erratum: “Seed layer technique for high quality epitaxial manganite films” [AIP Advances 6, 085109 (2016)]
No abstract available
Spin and Charge Correlations in Quantum Dots: An Exact Solution
The inclusion of charging and spin-exchange interactions within the Universal
Hamiltonian description of quantum dots is challenging as it leads to a
non-Abelian action. Here we present an {\it exact} analytical solution of the
probem, in particular, in the vicinity of the Stoner instabilty point. We
calculate several observables, including the tunneling density of states (TDOS)
and the spin susceptibility. Near the instability point the TDOS exhibits a
non-monotonous behavior as function of the tunneling energy, even at
temperatures higher than the exchange energy. Our approach is generalizable to
a broad set of observables, including the a.c. susceptibility and the
absorption spectrum for anisotropic spin interaction. Our results could be
tested in nearly ferromagnetic materials.Comment: JETPL class, 6 pages, 2 figure
Increasing the robustness of CUDA Fermi GPU-based systems
Nowadays Graphical processing Units (GPUs) have become increasingly popular due to their high computational power and low prices. This makes them particularly suitable for high-performance computing applications, like data elaboration and image processing. In these fields, the capability of properly work even in presence of faults is mandatory. This paper presents an innovative approach, that combines a Software Based Self Test & Diagnosis (SBSTD) methodology with a fault mitigation strategy, to increase the robustness of a CUDA Fermi GPU-based system
Equilibrium island-size distribution in one dimension
We derive an analytical expression for the size distribution of monoatomic wires in the framework of a one-dimensional lattice gas model at thermodynamic equilibrium. The theoretical results are compared with the size distribution of one-dimensional Ag wires obtained via nucleation at the step edges of the Pt(997) surface
Surface nanostructures in manganite films
Ultrathin manganite films are widely used as active electrodes in organic spintronic devices. In this study, a scanning tunnelling microscopy (STM) investigation with atomic resolution revealed previously unknown surface features consisting of small non-stoichiometric islands. Based upon this evidence, a new mechanism for the growth of these complex materials is proposed. It is suggested that the non-stoichiometric islands result from nucleation centres that are below the critical threshold size required for stoichiometric crystalline growth. These islands represent a kinetic intermediate of single-layer growth regardless of the film thickness, and should be considered and possibly controlled in manganite thin-film applications
Spin-Polarized STM for a Kondo adatom
We investigate the bias dependence of the tunneling conductance between a
spin-polarized (SP) scanning tunneling microscope (STM) tip and the surface
conduction states of a normal metal with a Kondo adatom. Quantum interference
between tip-host metal and tip-adatom-host metal conduction paths is studied in
the full range of the Fano parameter . The spin-polarized STM gives rise to
a splitting of the Kondo peak and asymmetry in the zero-bias anomaly depending
on the lateral tip-adatom distance. For increasing lateral distances, the Kondo
peak-splitting shows a strong suppression and the spin-polarized conductance
exhibits the standard Fano-Kondo profile.Comment: new version with improved discussion. added one figure. 12 pages
(one-column) + 5 figure
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