12,161 research outputs found
Predicting operator workload during system design
A workload prediction methodology was developed in response to the need to measure workloads associated with operation of advanced aircraft. The application of the methodology will involve: (1) conducting mission/task analyses of critical mission segments and assigning estimates of workload for the sensory, cognitive, and psychomotor workload components of each task identified; (2) developing computer-based workload prediction models using the task analysis data; and (3) exercising the computer models to produce predictions of crew workload under varying automation and/or crew configurations. Critical issues include reliability and validity of workload predictors and selection of appropriate criterion measures
Self-organized criticality in the Kardar-Parisi-Zhang-equation
Kardar-Parisi-Zhang interface depinning with quenched noise is studied in an
ensemble that leads to self-organized criticality in the quenched
Edwards-Wilkinson (QEW) universality class and related sandpile models. An
interface is pinned at the boundaries, and a slowly increasing external drive
is added to compensate for the pinning. The ensuing interface behavior
describes the integrated toppling activity history of a QKPZ cellular
automaton. The avalanche picture consists of several phases depending on the
relative importance of the terms in the interface equation. The SOC state is
more complicated than in the QEW case and it is not related to the properties
of the bulk depinning transition.Comment: 5 pages, 3 figures; accepted for publication in Europhysics Letter
Finite N Matrix Models of Noncommutative Gauge Theory
We describe a unitary matrix model which is constructed from discrete analogs
of the usual projective modules over the noncommutative torus and use it to
construct a lattice version of noncommutative gauge theory. The model is a
discretization of the noncommutative gauge theories that arise from toroidal
compactification of Matrix theory and it includes a recent proposal for a
non-perturbative definition of noncommutative Yang-Mills theory in terms of
twisted reduced models. The model is interpreted as a manifestly star-gauge
invariant lattice formulation of noncommutative gauge theory, which reduces to
ordinary Wilson lattice gauge theory for particular choices of parameters. It
possesses a continuum limit which maintains both finite spacetime volume and
finite noncommutativity scale. We show how the matrix model may be used for
studying the properties of noncommutative gauge theory.Comment: 17 pp, Latex2e; Typos corrected, references adde
Magnetic Backgrounds from Generalised Complex Manifolds
The magnetic backgrounds that physically give rise to spacetime
noncommutativity are generally treated using noncommutative geometry. In this
article we prove that also the theory of generalised complex manifolds contains
the necessary elements to generate B-fields geometrically. As an example, the
Poisson brackets of the Landau model (electric charges on a plane subject to an
external, perperdicularly applied magnetic field) are rederived using the
techniques of generalised complex manifolds.Comment: Some refs. adde
Quantum Black Holes, Elliptic Genera and Spectral Partition Functions
We study M-theory and D-brane quantum partition functions for microscopic
black hole ensembles within the context of the AdS/CFT correspondence in terms
of highest weight representations of infinite-dimensional Lie algebras,
elliptic genera, and Hilbert schemes, and describe their relations to elliptic
modular forms. The common feature in our examples lie in the modular properties
of the characters of certain representations of the pertinent affine Lie
algebras, and in the role of spectral functions of hyperbolic three-geometry
associated with q-series in the calculation of elliptic genera. We present new
calculations of supergravity elliptic genera on local Calabi-Yau threefolds in
terms of BPS invariants and spectral functions, and also of equivariant D-brane
elliptic genera on generic toric singularities. We use these examples to
conjecture a link between the black hole partition functions and elliptic
cohomology.Comment: 42 page
Characterisation of the Etching Quality in Micro-Electro-Mechanical Systems by Thermal Transient Methodology
Our paper presents a non-destructive thermal transient measurement method
that is able to reveal differences even in the micron size range of MEMS
structures. Devices of the same design can have differences in their
sacrificial layers as consequence of the differences in their manufacturing
processes e.g. different etching times. We have made simulations examining how
the etching quality reflects in the thermal behaviour of devices. These
simulations predicted change in the thermal behaviour of MEMS structures having
differences in their sacrificial layers. The theory was tested with
measurements of similar MEMS devices prepared with different etching times. In
the measurements we used the T3Ster thermal transient tester equipment. The
results show that deviations in the devices, as consequence of the different
etching times, result in different temperature elevations and manifest also as
shift in time in the relevant temperature transient curves.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
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