10,742 research outputs found
A technique for breaking ice in the path of a ship
A technique is described for breaking ice in the path of a ship. A laser is placed on the bow of the ship with apparatus to scan the ice in the path of the ship with the laser beam. The beam cuts or shatters the ice, enabling the ship to break the ice in its path
Modeling the emergence of universality in color naming patterns
The empirical evidence that human color categorization exhibits some
universal patterns beyond superficial discrepancies across different cultures
is a major breakthrough in cognitive science. As observed in the World Color
Survey (WCS), indeed, any two groups of individuals develop quite different
categorization patterns, but some universal properties can be identified by a
statistical analysis over a large number of populations. Here, we reproduce the
WCS in a numerical model in which different populations develop independently
their own categorization systems by playing elementary language games. We find
that a simple perceptual constraint shared by all humans, namely the human Just
Noticeable Difference (JND), is sufficient to trigger the emergence of
universal patterns that unconstrained cultural interaction fails to produce. We
test the results of our experiment against real data by performing the same
statistical analysis proposed to quantify the universal tendencies shown in the
WCS [Kay P and Regier T. (2003) Proc. Natl. Acad. Sci. USA 100: 9085-9089], and
obtain an excellent quantitative agreement. This work confirms that synthetic
modeling has nowadays reached the maturity to contribute significantly to the
ongoing debate in cognitive science.Comment: Supplementery Information available here
http://www.pnas.org/content/107/6/2403/suppl/DCSupplementa
Assessing the utility of environmental factors and objectives in environmental impact assessment practice: Western Australian insights
Environmental factors and objectives are formally identified during the scoping stage of environmental impact assessment (EIA) to structure and focus individual assessments. Environmental factors are broad components of the environment, while objectives set the desired outcome for a specific factor. This research assesses the utility of environmental factors and objectives in EIA practice based upon a combination of literature review and interviews with 21 EIA practitioners from Western Australia. Further to providing focus and structure for EIA, practitioners also use environmental factors and objectives for decision-making throughout the process. The majority of practitioners also note that factors and objectives are value adding and useful to their EIA practice. Due to their inherent subjective natures, interviewees noted a lack of consistency regarding how to meet the objectives and challenges in determining the significance of impacts on a factor. Identified opportunities to enhance use of objectives and factors in EIA included provision of more guidance, especially criteria or standards to apply and improve knowledge sharing between EIA stakeholders
Digital Repository of Mathematical Formulae
The purpose of the NIST Digital Repository of Mathematical Formulae (DRMF) is
to create a digital compendium of mathematical formulae for orthogonal
polynomials and special functions (OPSF) and of associated mathematical data.
The DRMF addresses needs of working mathematicians, physicists and engineers:
providing a platform for publication and interaction with OPSF formulae on the
web. Using MediaWiki extensions and other existing technology (such as software
and macro collections developed for the NIST Digital Library of Mathematical
Functions), the DRMF acts as an interactive web domain for OPSF formulae.
Whereas Wikipedia and other web authoring tools manifest notions or
descriptions as first class objects, the DRMF does that with mathematical
formulae. See http://gw32.iu.xsede.org/index.php/Main_Page
Short-range order and precipitation in Fe-rich Fe-Cr alloys: Atomistic off-lattice Monte Carlo simulations
Short-range order (SRO) in Fe-rich Fe-Cr alloys is investigated by means of
atomistic off-lattice Monte Carlo simulations in the semi-grand canonical
ensemble using classical interatomic potentials. The SRO parameter defined by
Cowley [Phys. Rev. B 77, 669 (1950)] is used to quantify the degree of
ordering. In agreement with experiments a strong ordering tendency in the Cr
distribution at low Cr concentrations (~< 5%) is observed, as manifested in
negative values of the SRO parameters. For intermediate Cr concentrations (5%
~< c_Cr ~< 15%) the SRO parameter for the alpha-phase goes through a minimum,
but at the solubility limit the alpha-phase still displays a rather strong SRO.
In thermodynamic equilibrium for concentrations within the two-phase region the
SRO parameter measured over the entire sample therefore comprises the
contributions from both the alpha and alpha-prime phases. If both of these
contributions are taken into account, it is possible to quantitatively
reproduce the experimental results and interpret their physical implications.
It is thereby shown that the inversion of the SRO observed experimentally is
due to the formation of stable (supercritical) alpha-prime precipitates. It is
not related to the loss of SRO in the alpha-phase or to the presence of
unstable (subcritical) Cr precipitates in the alpha-phase.Comment: 9 pages, 8 figure
PILOT: design and capabilities
The proposed design for PILOT is a general-purpose, wide-field 1 degree 2.4m,
f/10 Ritchey-Chretien telescope, with fast tip-tilt guiding, for use 0.5-25
microns. The design allows both wide-field and diffraction-limited use at these
wavelengths. The expected overall image quality, including median seeing, is
0.28-0.3" FWHM from 0.8-2.4 microns. Point source sensitivities are estimated.Comment: 4 pages, Proceedings of 2nd ARENA conference 'The Astrophysical
Science Cases at Dome C', Potsdam, 17-21 September 200
Jastrow correlation factor for atoms, molecules, and solids
A form of Jastrow factor is introduced for use in quantum Monte Carlo
simulations of finite and periodic systems. Test data are presented for atoms,
molecules, and solids, including both all-electron and pseudopotential atoms.
We demonstrate that our Jastrow factor is able to retrieve a large fraction of
the correlation energy
Negative oxygen vacancies in HfO as charge traps in high-k stacks
We calculated the optical excitation and thermal ionization energies of
oxygen vacancies in m-HfO using atomic basis sets, a non-local density
functional and periodic supercell. The thermal ionization energies of
negatively charged V and V centres are consistent with values
obtained by the electrical measurements. The results suggest that negative
oxygen vacancies are the likely candidates for intrinsic electron traps in the
hafnum-based gate stack devices.Comment: 3 pages, 2 figure
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