4,926 research outputs found
Partially ordered distributed computations on asynchronous point-to-point networks
Asynchronous executions of a distributed algorithm differ from each other due
to the nondeterminism in the order in which the messages exchanged are handled.
In many situations of interest, the asynchronous executions induced by
restricting nondeterminism are more efficient, in an application-specific
sense, than the others. In this work, we define partially ordered executions of
a distributed algorithm as the executions satisfying some restricted orders of
their actions in two different frameworks, those of the so-called event- and
pulse-driven computations. The aim of these restrictions is to characterize
asynchronous executions that are likely to be more efficient for some important
classes of applications. Also, an asynchronous algorithm that ensures the
occurrence of partially ordered executions is given for each case. Two of the
applications that we believe may benefit from the restricted nondeterminism are
backtrack search, in the event-driven case, and iterative algorithms for
systems of linear equations, in the pulse-driven case
Finite-size, magnetic and chemical-potential effects on first-order phase transitions
We perform a study about effects of an applied magnetic field and a finite
chemical potential on the size-dependent phase structure of a first-order
transition. These effects are introduced by using methods of quantum fields
defined on toroidal spaces, and we study in particular the case of two
compactified dimensions, imaginary time and a spatial one (a heated film). It
is found that for any value of the applied field, there is a minimal size of
the system, independent of the chemical potential, below which the transition
disappears.Comment: 19 pages, 3 figures, version accepted for publication in Phys. Lett.
High frequency magnetic behavior through the magnetoimpedance effect in CoFeB/(Ta, Ag, Cu) multilayered ferromagnetic thin films
We studied the dynamics of magnetization through an investigation of the
magnetoimpedance effect in CoFeB/(Ta, Ag, Cu) multilayered thin films grown by
magnetron sputtering. Impedance measurements were analyzed in terms of the
mechanisms responsible for their variations at different frequency intervals
and the magnetic and structural properties of the multilayers. Analysis of the
mechanisms responsible for magnetoimpedance according to frequency and external
magnetic field showed that for the CoFeB/Cu multilayer, ferromagnetic resonance
(FMR) contributes significantly to the magnetoimpedance effect at frequencies
close to 470 MHz. This frequency is low when compared to the results obtained
for CoFeB/Ta and CoFeB/Ag multilayers and is a result of the anisotropy
distribution and non-formation of regular bilayers in this sample. The MImax
values occurred at different frequencies according to the used non-magnetic
metal. Variations between 25% and 30% were seen for a localized frequency band,
as in the case of CoFeB/Ta and CoFeB/Ag, as well as for a wide frequency range,
in the case of CoFeB/Cu.Comment: 14 pages, 5 figure
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