32,862 research outputs found
Development of advanced digital techniques for data acquisition processing and communication Interim scientific report
Design, video data characteristics, error control, and compression algorithms for Mars television mapping missio
PFM Simulator
Pulse frequency modulation simulator for design and testing of telemetry equipment for satellite system
The diocotron instability in a quasi-toroidal geometry
Slipstream instability of low density electron beams in crossed electric and magnetic field
Context unification is in PSPACE
Contexts are terms with one `hole', i.e. a place in which we can substitute
an argument. In context unification we are given an equation over terms with
variables representing contexts and ask about the satisfiability of this
equation. Context unification is a natural subvariant of second-order
unification, which is undecidable, and a generalization of word equations,
which are decidable, at the same time. It is the unique problem between those
two whose decidability is uncertain (for already almost two decades). In this
paper we show that the context unification is in PSPACE. The result holds under
a (usual) assumption that the first-order signature is finite.
This result is obtained by an extension of the recompression technique,
recently developed by the author and used in particular to obtain a new PSPACE
algorithm for satisfiability of word equations, to context unification. The
recompression is based on performing simple compression rules (replacing pairs
of neighbouring function symbols), which are (conceptually) applied on the
solution of the context equation and modifying the equation in a way so that
such compression steps can be in fact performed directly on the equation,
without the knowledge of the actual solution.Comment: 27 pages, submitted, small notation changes and small improvements
over the previous tex
Different steady states for spin currents in noncollinear multilayers
We find there are at least two different steady states for transport across
noncollinear magnetic multilayers. In the conventional one there is a
discontinuity in the spin current across the interfaces which has been
identified as the source of current induced magnetic reversal; in the one
advocated herein the spin torque arises from the spin accumulation transverse
to the magnetization of a magnetic layer. These two states have quite different
attributes which should be discerned by current experiments.Comment: 8 pages, no figure. Accepted for publication in Journal of Physics:
Condensed Matte
Development of advanced digital techniques for data acquisition processing and communication Interim scientific report
Image correlation and computerized simulation applied to data acquisition and imaging technique
An ion resonance instability in grossly non-neutral plasmas
Ion resonance instability in grossly non-neutral plasma
Lateral diffusive spin transport in layered structures
A one dimensional theory of lateral spin-polarized transport is derived from
the two dimensional flow in the vertical cross section of a stack of
ferromagnetic and paramagnetic layers. This takes into account the influence of
the lead on the lateral current underneath, in contrast to the conventional 1D
modeling by the collinear configuration of lead/channel/lead. Our theory is
convenient and appropriate for the current in plane configuration of an
all-metallic spintronics structure as well as for the planar structure of a
semiconductor with ferromagnetic contacts. For both systems we predict the
optimal contact width for maximal magnetoresistance and propose an electrical
measurement of the spin diffusion length for a wide range of materials.Comment: 4 pages, 3 figure
Upstairs downstairs: how introducing computer technology changed skills and pay on two floors of Cabot Bank
Assessing the differing impacts of a new computer technology on skills and pay in two departments of a large bank.Checks ; Check collection systems ; Check float ; Job security ; Employees, Training of
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