86,614 research outputs found
On the Moduli Space of SU(3) Seiberg-Witten Theory with Matter
We present a qualitative model of the Coulomb branch of the moduli space of
low-energy effective N=2 SQCD with gauge group SU(3) and up to five flavours of
massive matter. Overall, away from double cores, we find a situation broadly
similar to the case with no matter, but with additional complexity due to the
proliferation of extra BPS states. We also include a revised version of the
pure SU(3) model which can accommodate just the orthodox weak coupling
spectrum.Comment: 32 pages, 25 figures, uses JHEP.cls, added references, deleted joke
Nonlinear Cosmological Power Spectra in Real and Redshift--Space
We present an expression for the nonlinear evolution of the cosmological
power spectrum based on following Lagrangian trajectories. This is simplified
using the Zel'dovich approximation to trace particle displacements, assuming
Gaussian initial conditions. The model is found to exhibit the transfer of
power from large to small scales expected in self- gravitating fields. We have
extended this analysis into redshift-space and found a solution for the
nonlinear, anisotropic redshift-space power spectrum in the limit of
plane--parallel redshift distortions. The quadrupole-to- monopole ratio is
calculated for the case of power-law initial spectra. We find that the shape of
this ratio depends on the shape of the initial spectrum, but when scaled to
linear theory depends only weakly on the redshift-space distortion parameter,
. The point of zero-crossing of the quadrupole, , is found to obey
a scaling relation. This model is found to be in agreement with -body
simulations on scales down to the zero-crossing of the quadrupole, although the
wavenumber at zero-crossing is underestimated. These results are applied to the
quadrupole--monopole ratio found in the merged QDOT+1.2 Jy IRAS redshift
survey. We have estimated that the distortion parameter is constrained to be
at the level. The local primordial spectral slope is not
well constrained, but analysis suggests in the translinear
regime. The zero-crossing scale of the quadrupole is
and from this we infer the amplitude of clustering is .
We suggest that the success of this model is due to nonlinear redshift--space
effects arising from infall onto caustics and is not dominated by virialised
cluster cores.Comment: 13 pages, uufiles, Latex with 6 postscript figures, submitted to
MNRA
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Steps to an advanced Ada programming environment
Conceptual simplicity, tight coupling of tools, and effective support of host-target software development will characterize advanced Ada programming support environments. Several important principles have been demonstrated in the Arcturus system, including template-assisted Ada editing, command completion using Ada as a command language, and combining the advantages of interpretation and compliation. Other principles, relating to analysis, testing, and debugging of concurrent Ada programs, have appeared in other contexts. This paper discusses several of these topics, considers how they can be integrated, and argues for their inclusion in an environment appropriate for software development in the late 1980's
Information standards to support application and enterprise interoperability for the smart grid
Copyright @ 2012 IEEE.Current changes in the European electricity industry are driven by regulatory directives to reduce greenhouse gas emissions, at the same time as replacing aged infrastructure and maintaining energy security. There is a wide acceptance of the requirement for smarter grids to support such changes and accommodate variable injections from renewable energy sources. However the design templates are still emerging to manage the level of information required to meet challenges such as balancing, planning and market dynamics under this new paradigm. While secure and scalable cloud computing architectures may contribute to supporting the informatics challenges of the smart grid, this paper focuses on the essential need for business alignment with standardised information models such as the IEC Common Information Model (CIM), to leverage data value and control system interoperability. In this paper we present details of use cases being considered by National Grid, the GB transmission system operator for information interoperability in pan-network system management and planning.This study is financially supported by the National Grid, UK
Smart grid interoperability use cases for extending electricity storage modeling within the IEC Common Information Model
Copyright @ 2012 IEEEThe IEC Common Information Model (CIM) is recognized as a core standard, supporting electricity transmission system interoperability. Packages of UML classes make up its domain ontology to enable a standardised abstraction of network topology and proprietary power system models. Since the early days of its design, the CIM has grown to reflect the widening scope and detail of utility information use cases as the desire to interoperate between a greater number of systems has increased. The cyber-physical nature of the smart grid places even greater demand upon the CIM to model future scenarios for power system operation and management that are starting to arise. Recent developments of modern electricity networks have begun to implement electricity storage (ES) technologies to provide ancillary balancing services, useful to grid integration of large-scale renewable energy systems. In response to this we investigate modeling of grid-scale electricity storage, by drawing on information use cases for future smart grid operational scenarios at National Grid, the GB Transmission System Operator. We find current structures within the CIM do not accommodate the informational requirements associated with novel ES systems and propose extensions to address this requirement.This study is supported by the UK National Grid and Brunel Universit
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