11,068 research outputs found
Composing Scalable Nonlinear Algebraic Solvers
Most efficient linear solvers use composable algorithmic components, with the
most common model being the combination of a Krylov accelerator and one or more
preconditioners. A similar set of concepts may be used for nonlinear algebraic
systems, where nonlinear composition of different nonlinear solvers may
significantly improve the time to solution. We describe the basic concepts of
nonlinear composition and preconditioning and present a number of solvers
applicable to nonlinear partial differential equations. We have developed a
software framework in order to easily explore the possible combinations of
solvers. We show that the performance gains from using composed solvers can be
substantial compared with gains from standard Newton-Krylov methods.Comment: 29 pages, 14 figures, 13 table
Pneumatic Construction Applied to Multistory Buildings
Extension of the principles of pneumatic construction to include multistory buildings is discussed by Peter R. Smith, Senior Lecturer in Architectural Science at The University of Sydney (Australia) and Jens G. Pohl, Lecturer, School of Architecture and Building, University of New South Wales
Yes, subjective norms are important, but let's not lose sight of cultural differences
The study of social norms has great potential to broaden our understanding of the ways in which cultures are created and maintained. To maximise the benefit of this perspective, it is important to sample cultures widely and to include contexts in which norms are injunctiv
Journal publishing with Acrobat: the CAJUN project
The publication of material in electronic form should ideally preserve, in a unified document representation, all of the richness of the printed document while maintaining enough of its underlying structure to enable searching and other forms of semantic processing. Until recently it has been hard to find a document representation which combined these attributes and which also stood some chance of becoming a de facto multi-platform standard.
This paper sets out experience gained within the Electronic Publishing Research Group at the University of Nottingham in using Adobe Acrobat software and its underlying PDF (Portable Document Format) notation. The CAJUN project1 (CD-ROM Acrobat Journals Using Networks) began in 1993 and has used Acrobat software to produce electronic versions of journal papers for network and CD-ROM dissemination. The paper describes the project's progress so far and also gives a brief assessment of PDF's suitability as a universal document interchange standard
Homogeneous Photometry V: The Globular Cluster NGC 4147
New BVRI broad-band photometry and astrometry are presented for the globular
cluster NGC 4147, based upon measurements derived from 524 ground-based CCD
images mostly either donated by colleagues or retrieved from public archives.
We have also reanalysed five exposures of the cluster obtained with WFPC2 on
the Hubble Space Telescope in the F439W and F555W (B and V) filters. We present
calibrated color-magnitude and color-color diagrams. Analysis of the
color-magnitude diagram reveals morphogical properties generally consistent
with published metal-abundance estimates for the cluster, and an age typical of
other Galactic globular clusters of similar metallicity. We have also
redetermined the periods and mean magnitudes for the RR Lyrae variables,
including a new c-type variable reported here for the first time. Our data do
not show clear evidence for photometric variability in candidate V18, recently
reported by Arellano Ferro et al. (2004). These observations also support the
non-variable status of candidates V5, V9, and V15. The union of our light-curve
data with those of Newburn (1957), Mannino (1957) and Arellano Ferro et al.
(op. cit.) permits the derivation of significantly improved periods. The mean
periods and the Bailey period-amplitude diagrams support the classification of
the cluster as Oosterhoff I despite its predominantly blue horizontal branch.
The number ratio of c- to ab-type RR Lyrae stars, on the other hand, is
unusually high for an Oosterhoff I cluster. The calibrated results have been
made available through the first author's web site.Comment: 30 pages, 30 figures. PASP, in press. Uses 11/2004 version of
emulateapj (included). For the full-resolution preprint, the reader is
encouraged to download the ps file (123 pages, manuscript format) available
at http://cadcwww.hia.nrc.ca/stetson/NGC4147/ms.ps.gz, or the pdf file (30
pages, preprint format) available at
http://www.astro.puc.cl/~mcatelan/N4147/full-res.pd
A two-way photonic interface for linking Sr+ transition at 422 nm to the telecommunications C-band
We report a single-stage bi-directional interface capable of linking Sr+
trapped ion qubits in a long-distance quantum network. Our interface converts
photons between the Sr+ emission wavelength at 422 nm and the telecoms C-band
to enable low-loss transmission over optical fiber. We have achieved both up-
and down-conversion at the single photon level with efficiencies of 9.4% and
1.1% respectively. Furthermore we demonstrate noise levels that are low enough
to allow for genuine quantum operation in the future.Comment: 5 pages, 4 figure
The Genetic and Environmental Foundations of Political, Psychological, Social, and Economic Behaviors: A Panel Study of Twins and Families
Here we introduce the Genetic and Environmental Foundations of Political and Economic Behaviors: A Panel Study of Twins and Families (PIs Alford, Hatemi, Hibbing, Martin, and Smith). This study was designed to explore the genetic and environmental influences on social, economic, and political behaviors and attitudes. It involves identifying the psychological mechanisms that operate on these traits, the heritability of complex economic and political traits under varying conditions, and specific genetic correlates of attitudes and behaviors. In addition to describing the study, we conduct novel analyses on the data, estimating the heritability of two traits so far unexplored in the extant literature: Machiavellianism and Baron-Cohen’s Empathizing Quotient
Modelling extreme concentration from a source in a turbulent flow over rough wall
The concentration fluctuations in passive plumes from an elevated and a groundlevel
source in a turbulent boundary layer over a rough wall were studied using
large eddy simulation and wind tunnel experiment. The predictions of statistics
up to second order moments were thereby validated. In addition, the trend of relative
fluctuations far downstream for a ground level source was estimated using
dimensional analysis. The techniques of extreme value theory were then applied
to predict extreme concentrations by modelling the upper tail of the probability
density function of the concentration time series by the Generalised Pareto Distribution.
Data obtained from both the simulations and experiments were analysed in
this manner. The predicted maximum concentration (?0) normalized by the local
mean concentration (Cm) or by the local r.m.s of concentration fluctuation (crms),
was extensively investigated. Values for ?0/Cm and ?0/crms as large as 50 and 20
respectively were found for the elevated source and 10 and 15 respectively for the
ground-level source
Ultraviolet writing of channel waveguides in proton-exchanged LiNbO<sub>3</sub>
We report on a direct ultraviolet (UV) writing method for the fabrication of channel waveguides at 1.55 µm in LiNbO3 through UV irradiation of surface and buried planar waveguides made by annealed proton exchange and reverse proton exchange. A systematic study of the guidance properties as a function of the UV writing conditions is presented
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