3,123 research outputs found
Identifying how automation can lose its intended benefit along the development process : a research plan
Doctoral Consortium Presentation © The Authors 2009Automation is usually considered to improve performance in virtually any domain. However it can fail to deliver the target benefit as intended by those managers and designers advocating the introduction of the tool. In safety critical domains this problem is of significance not only because the unexpected effects of automation might prevent its widespread usage but also because they might turn out to be a contributor to incident and accidents. Research on failures of automation to deliver the intended benefit has focused mainly on human automation interaction. This paper presents a PhD research plan that aims at characterizing decisions for those involved in development process of automation for safety critical domains, taken under productive pressure, to identify where and when the initial intention the automation is supposed to deliver can be lost along the development process. We tentatively call such decisions as drift and the final objective is to develop principles that will allow to identify and compensate for possible sources of drift in the development of new automation. The research is based on case studies and is currently entering Year 2
The argali (Ovis ammon antiqua) from the Magliana area (Rome)
During the Middle Pleistocene, the subspecies was widespread from Georgia to Portugal, though it is scantily recorded in local faunal assemblages of Southern Europe. Its occurrence in a few Late Pleistocene sites needs to be confirmed. In Italy, the subspecies is recorded in the late Galerian fauna of Visogliano (MIS 13 - 10) as well as in the Magliana area, where an incomplete skull was found at the beginning of the last century. Although the precise location where this specimen was found is unknown, on the basis of the results of the geochemical analysis performed on a small amount of sediment, sampled from the filling of the inner cavities of the horn-cores, and considering the stratigraphy of the area, the hypothesis that the skull comes from the deposits of the PG4 sequence (MIS14 partim - MIS13) cannot be ruled out. This hypothetical remark would confirm the occurrence in Italy of the argali in late Galerian faunas. The dimensions of Ovis ammon antiqua from the Magliana area fit well within the range of variability of the larger specimens, likely males, found at La Caune de L’Arago (France) (MIS 14-12), from which the Italian specimen differs in having less twisted and more dorso-ventrally curved horn-cores
Spin entanglement in atoms and molecules
We investigate the effects of inhomogeneities on spin entanglement in
many-electron systems from an ab-initio approach. The key quantity in our
approach is the local spin entanglement length, which is derived from the local
concurrence of the electronic system. Although the concurrence for an
interacting systems is a highly nonlocal functional of the density, it does
have a simple, albeit approximate expression in terms of Kohn-Sham orbitals. We
show that the electron localization function -- well known in quantum chemistry
as a descriptor of atomic shells and molecular bonds -- can be reinterpreted in
terms of the ratio of the local entanglement length of the inhomogeneous system
to the entanglement length of a homogenous system at the same density. We find
that the spin entanglement is remarkably enhanced in atomic shells and
molecular bonds
Bonds, lone pairs, and shells probed by means of on-top dynamical correlations
The Electron Localization Function (ELF) by Becke and Edgecombe [J. Chem.
Phys. {\bf 92}, 5397 (1990)] is routinely adopted as a descriptor of atomic
shells and covalent bonds. Since the ELF and its related quantities find useful
exploitation also in the construction of modern density functionals, the
interest in complementing the ELF is linked to both the quests of improving
electronic structure descriptors and density functional approximations. The ELF
uses information which is available by considering parallel-spin electron pairs
in single-reference many-body states. In this work, we complement this
construction with information obtained by considering antiparallel-spin pairs
whose short-range correlations are modeled by a density functional
approximation. As a result, the approach requires only a contained
computational effort. Applications to a variety of systems show that, in this
way, we gain a spatial description of the bond in H (which is not available
with the ELF) together with some trends not optimally captured by the ELF in
other prototypical situations
Ab initio Simulation of Optical Limiting: The Case of Metal-Free Phthalocyanine
We present a fully ab initio, non-perturbative description of the optical
limiting properties of a metal-free phthalocyanine, by simulating the effects
of a broadband electric field of increasing intensity. The results confirm
reverse saturable absorption as leading mechanism for optical limiting
phenomena in this system and reveal that a number of dipole-forbidden
excitations are populated by excited-state absorption, at more intense external
fields. The excellent agreement with the experimental data supports our
approach as a powerful tool to predict optical limiting, in view of
applications
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