8,462 research outputs found
A Trust Model Based on Service Classification in Mobile Services
Internet of Things (IoT) and B3G/4G communication are promoting the pervasive
mobile services with its advanced features. However, security problems are also
baffled the development. This paper proposes a trust model to protect the
user's security. The billing or trust operator works as an agent to provide a
trust authentication for all the service providers. The services are classified
by sensitive value calculation. With the value, the user's trustiness for
corresponding service can be obtained. For decision, three trust regions are
divided, which is referred to three ranks: high, medium and low. The trust
region tells the customer, with his calculated trust value, which rank he has
got and which authentication methods should be used for access. Authentication
history and penalty are also involved with reasons.Comment: IEEE/ACM Internet of Things Symposium (IOTS), in conjunction with
GreenCom 2010, IEEE, Hangzhou, China, December 18-20, 201
Spin-flip reflection at the normal metal-spin superconductor interface
We study spin transport through a normal metal-spin superconductor junction.
A spin-flip reflection is demonstrated at the interface, where a spin-up
electron incident from the normal metal can be reflected as a spin-down
electron and the spin will be injected into the spin
superconductor. When the (spin) voltage is smaller than the gap of the spin
superconductor, the spin-flip reflection determines the transport properties of
the junction. We consider both graphene-based (linear-dispersion-relation) and
quadratic-dispersion-relation normal metal-spin superconductor junctions in
detail. For the two-dimensional graphene-based junction, the spin-flip
reflected electron can be along the specular direction (retro-direction) when
the incident and reflected electron locates in the same band (different bands).
A perfect spin-flip reflection can occur when the incident electron is normal
to the interface, and the reflection coefficient is slightly suppressed for the
oblique incident case. As a comparison, for the one-dimensional
quadratic-dispersion-relation junction, the spin-flip reflection coefficient
can reach 1 at certain incident energies. In addition, both the charge current
and the spin current under a charge (spin) voltage are studied. The spin
conductance is proportional to the spin-flip reflection coefficient when the
spin voltage is less than the gap of the spin superconductor. These results
will help us get a better understanding of spin transport through the normal
metal-spin superconductor junction.Comment: 11 pages, 9 figure
Ginzburg-Landau-type theory of non-polarized spin superconductivity
Since the concept of spin superconductor was proposed, all the related
studies concentrate on spin-polarized case. Here, we generalize the study to
spin-non-polarized case. The free energy of non-polarized spin superconductor
is obtained, and the Ginzburg-Landau-type equations are derived by using the
variational method. These Ginzburg-Landau-type equations can be reduced to the
spin-polarized case when the spin direction is fixed. Moreover, the expressions
of super linear and angular spin currents inside the superconductor are
derived. We demonstrate that the electric field induced by super spin current
is equal to the one induced by equivalent charge obtained from the second
Ginzburg-Landau-type equation, which shows self-consistency of our theory. By
applying these Ginzburg-Landau-type equations, the effect of electric field on
the superconductor is also studied. These results will help us get a better
understanding of the spin superconductor and the related topics such as
Bose-Einstein condensate of magnons and spin superfluidity.Comment: 9 pages, 5 figure
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