49,248 research outputs found
A comparative reliability analysis of ETCS train radio communications
StoCharts have been proposed as a UML statechart extension for performance and dependability evaluation, and were applied in the context of train radio reliability assessment to show the principal tractability of realistic cases with this approach. In this paper, we extend on this bare feasibility result in two important directions. First, we sketch the cornerstones of a mechanizable translation of StoCharts to MoDeST. The latter is a process algebra-based formalism supported by the Motor/Möbius tool tandem. Second, we exploit this translation for a detailed analysis of the train radio case study
From StoCharts to MoDeST: a comparative reliability analysis of train radio communications
StoCharts have been proposed as a UML statechart extension for performance and dependability evaluation, and have been applied in the context of train radio reliability assessment to show the principal tractability of realistic cases with this approach. In this paper, we extend on this bare feasibility result in two important directions. First, we sketch the cornerstones of a mechanizable translation of StoCharts to MoDeST. The latter is a process algebra-based formalism supported by the Motor/Möbius tool tandem. Second, we exploit this translation for a detailed analysis of the train radio case study
Investigating Decision Support Techniques for Automating Cloud Service Selection
The compass of Cloud infrastructure services advances steadily leaving users
in the agony of choice. To be able to select the best mix of service offering
from an abundance of possibilities, users must consider complex dependencies
and heterogeneous sets of criteria. Therefore, we present a PhD thesis proposal
on investigating an intelligent decision support system for selecting Cloud
based infrastructure services (e.g. storage, network, CPU).Comment: Accepted by IEEE Cloudcom 2012 - PhD consortium trac
Complex Systems: A Survey
A complex system is a system composed of many interacting parts, often called
agents, which displays collective behavior that does not follow trivially from
the behaviors of the individual parts. Examples include condensed matter
systems, ecosystems, stock markets and economies, biological evolution, and
indeed the whole of human society. Substantial progress has been made in the
quantitative understanding of complex systems, particularly since the 1980s,
using a combination of basic theory, much of it derived from physics, and
computer simulation. The subject is a broad one, drawing on techniques and
ideas from a wide range of areas. Here I give a survey of the main themes and
methods of complex systems science and an annotated bibliography of resources,
ranging from classic papers to recent books and reviews.Comment: 10 page
Recommended from our members
Individual common variants exert weak effects on the risk for autism spectrum disorders.
While it is apparent that rare variation can play an important role in the genetic architecture of autism spectrum disorders (ASDs), the contribution of common variation to the risk of developing ASD is less clear. To produce a more comprehensive picture, we report Stage 2 of the Autism Genome Project genome-wide association study, adding 1301 ASD families and bringing the total to 2705 families analysed (Stages 1 and 2). In addition to evaluating the association of individual single nucleotide polymorphisms (SNPs), we also sought evidence that common variants, en masse, might affect the risk. Despite genotyping over a million SNPs covering the genome, no single SNP shows significant association with ASD or selected phenotypes at a genome-wide level. The SNP that achieves the smallest P-value from secondary analyses is rs1718101. It falls in CNTNAP2, a gene previously implicated in susceptibility for ASD. This SNP also shows modest association with age of word/phrase acquisition in ASD subjects, of interest because features of language development are also associated with other variation in CNTNAP2. In contrast, allele scores derived from the transmission of common alleles to Stage 1 cases significantly predict case status in the independent Stage 2 sample. Despite being significant, the variance explained by these allele scores was small (Vm< 1%). Based on results from individual SNPs and their en masse effect on risk, as inferred from the allele score results, it is reasonable to conclude that common variants affect the risk for ASD but their individual effects are modest
Cosmology with varying scales and couplings
The time variation of fundamental mass scales can have profound cosmological
implications. We investigate a particular model of crossover quintessence which
is compatible with all present cosmological observations. This model can also
reconcile the reported time variation of the fine structure constant from
quasar absorption lines with the bounds from archeo-nuclear physics and tests
of the equivalence principle.Comment: 20 pages, LaTe
Gauge Unification in Extra Dimensions: Power Corrections vs. Higher-Dimension Operators
Power-like loop corrections to gauge couplings are a generic feature of
higher-dimensional field theories. In supersymmetric grand unified theories in
d=5 dimensions, such corrections arise only in the presence of a vacuum
expectation value of the adjoint scalar of the gauge multiplet. We show that,
using the analysis of the exact quantum effective action by Intriligator,
Morrison and Seiberg, these power corrections can be understood as the effect
of higher-dimension operators. Such operators, both classical and quantum, are
highly constrained by gauge symmetry and supersymmetry. As a result, even
non-perturbatively large contributions to gauge coupling unification can be
unambiguously determined within 5d low-energy effective field theory. Since no
massive hypermultiplet matter exists in 6 dimensions, the predictivity is
further enhanced by embedding the 5d model in a 6d gauge theory relevant at
smaller distances. Thus, large and quantitatively controlled power-law
contributions to gauge couplings arise naturally and can, in the most extreme
case, lead to calculable TeV-scale power law unification. We identify a simple
5d SU(5) model with one massless 10 in the bulk where the power-law effect is
exactly MSSM-like.Comment: 29 pages, 2 figures, LaTeX, v3: references added and typos correcte
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