2,276 research outputs found
Extracting the intrinsic switching field distribution in perpendicular media: a comparative analysis
We introduce a new method based on the first-order-reversal-curve (FORC)
diagram to extract the intrinsic (microscopic) switching-field distribution
(SFD) of perpendicular recording media (PRM). To demonstrate the viability of
the method, we micromagnetically simulated FORCs for PRM with known SFD and
compare the extracted SFD with the SFD obtained by means of two different
methods that are based on recoil loops, too, which however rely on mean-field
approximations and assumptions on the shape of the SFD. The FORC method turns
out to be the most accurate algorithm over a broad range of dipolar interaction
strengths, where the other methods overestimate the width of the SFD.Comment: 3 pages with 2 figures, 3 supplemental figures; submitted to J. Appl.
Phys. (MMM Annual Conference Proceedings
Chebyshev constants for the unit circle
It is proven that for any system of n points z_1, ..., z_n on the (complex)
unit circle, there exists another point z of norm 1, such that
Equality holds iff the point system is a
rotated copy of the nth unit roots.
Two proofs are presented: one uses a characterisation of equioscillating
rational functions, while the other is based on Bernstein's inequality.Comment: 11 page
Superconducting single-charge transistor in a tunable dissipative environment
We study a superconducting single-charge transistor, where the coherence of
Cooper pair tunneling is destroyed by the coupling to a tunable dissipative
environment. Sequential tunneling and cotunneling processes are analyzed to
construct the shape of the conductance peaks and their dependence on the
dissipation and temperature. Unexpected features are found due to a cross-over
between two distinct regimes, one `environment-assisted' the other
`environment-dominated'. Several of the predictions have been confirmed by
recent experiments. The model and results apply also to the dynamics of
Josephson junction quantum bits on a conducting ground plane, thus explaining
the influence of dissipation on the coherence.Comment: Strongly revied version as accepted by Phys. Rev. Let
Gravitational radiation reaction in compact binary systems: Contribution of the quadrupole-monopole interaction
The radiation reaction in compact spinning binaries on eccentric orbits due
to the quadrupole-monopole interaction is studied. This contribution is of
second post-Newtonian order. As result of the precession of spins the magnitude
of the orbital angular momentum is not conserved. Therefore a proper
characterization of the perturbed radial motion is provided by the energy
and angular average . As powerful computing tools, the generalized
true and eccentric anomaly parametrizations are introduced. Then the secular
losses in energy and magnitude of orbital angular momentum together with the
secular evolution of the relative orientations of the orbital angular momentum
and spins are found for eccentric orbits by use of the residue theorem. The
circular orbit limit of the energy loss agrees with Poisson's earlier result.Comment: accepted for publication in Phys. Rev.
CAN ROBOTS LAUGH?
For knowledge based systems knowledge, which is usually given as natural language descriptions, has to be transferred into formal representations. The authors argue that the expressive power of natural language lies partially in the possibility that it can be considered as a rich system of sublanguages. The category of theory morphisms is an adequate mathematical tool to handle the sublanguages of different subfields, different points of references and different levels of abstraction. To prove the claim jokes are analysed and it is shown that in this way a very abstract logical characterisation can be given. The paper tries to answer even the question in the title
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