109,745 research outputs found
Software timing analysis for complex hardware with survivability and risk analysis
The increasing automation of safety-critical real-time systems, such as those in cars and planes, leads, to more complex and performance-demanding on-board software and the subsequent adoption of multicores and accelerators. This causes software's execution time dispersion to increase due to variable-latency resources such as caches, NoCs, advanced memory controllers and the like. Statistical analysis has been proposed to model the Worst-Case Execution Time (WCET) of software running such complex systems by providing reliable probabilistic WCET (pWCET) estimates. However, statistical models used so far, which are based on risk analysis, are overly pessimistic by construction. In this paper we prove that statistical survivability and risk analyses are equivalent in terms of tail analysis and, building upon survivability analysis theory, we show that Weibull tail models can be used to estimate pWCET distributions reliably and tightly. In particular, our methodology proves the correctness-by-construction of the approach, and our evaluation provides evidence about the tightness of the pWCET estimates obtained, which allow decreasing them reliably by 40% for a railway case study w.r.t. state-of-the-art exponential tails.This work is a collaboration between Argonne National Laboratory and the Barcelona Supercomputing Center within the Joint Laboratory for Extreme-Scale Computing. This research is supported by the
U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research, under contract number DE-AC02-
06CH11357, program manager Laura Biven, and by the Spanish Government (SEV2015-0493), by the Spanish Ministry of Science and Innovation (contract TIN2015-65316-P), by Generalitat de Catalunya (contract 2014-SGR-1051).Peer ReviewedPostprint (author's final draft
Statistical modelling of software reliability
During the six-month period from 1 April 1991 to 30 September 1991 the following research papers in statistical modeling of software reliability appeared: (1) A Nonparametric Software Reliability Growth Model; (2) On the Use and the Performance of Software Reliability Growth Models; (3) Research and Development Issues in Software Reliability Engineering; (4) Special Issues on Software; and (5) Software Reliability and Safety
Heavy-Tailed Features and Empirical Analysis of the Limit Order Book Volume Profiles in Futures Markets
This paper poses a few fundamental questions regarding the attributes of the
volume profile of a Limit Order Books stochastic structure by taking into
consideration aspects of intraday and interday statistical features, the impact
of different exchange features and the impact of market participants in
different asset sectors. This paper aims to address the following questions:
1. Is there statistical evidence that heavy-tailed sub-exponential volume
profiles occur at different levels of the Limit Order Book on the bid and ask
and if so does this happen on intra or interday time scales ?
2.In futures exchanges, are heavy tail features exchange (CBOT, CME, EUREX,
SGX and COMEX) or asset class (government bonds, equities and precious metals)
dependent and do they happen on ultra-high (<1sec) or mid-range (1sec -10min)
high frequency data?
3.Does the presence of stochastic heavy-tailed volume profile features evolve
in a manner that would inform or be indicative of market participant behaviors,
such as high frequency algorithmic trading, quote stuffing and price discovery
intra-daily?
4. Is there statistical evidence for a need to consider dynamic behavior of
the parameters of models for Limit Order Book volume profiles on an intra-daily
time scale ?
Progress on aspects of each question is obtained via statistically rigorous
results to verify the empirical findings for an unprecedentedly large set of
futures market LOB data. The data comprises several exchanges, several futures
asset classes and all trading days of 2010, using market depth (Type II) order
book data to 5 levels on the bid and ask
Rammed Earth Construction: A Proposal for a Statistical Quality Control in the Execution Process
Unlike other common contemporary construction materials such as concrete, mortars,
or fired clay bricks, which are widely supported by international standards and regulations,
building with rammed earth is barely regulated. Furthermore, its quality control is usually problematic,
which regularly encourages the rejection of this technique. In the literature, many authors have
suggested ways to safely build a rammed earth wall, but only a few of them have delved into its
quality control before and during the construction process. This paper introduces a preliminary
methodology and establishes unified criteria, based in a statistical analysis, for both the production
and the quality control of this constructive technique in cases dealing with both samples and walls
P-MaNGA : full spectral fitting and stellar population maps from prototype observations
MC acknowledges support from a Royal Society University Research Fellowship.MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a 6-yearSDSS-IV survey that will obtain resolved spectroscopy from 3600 Å to10300 Å for a representative sample of over 10,000 nearby galaxies.In this paper, we derive spatially resolved stellar population properties and radial gradients by performing full spectral fitting of observed galaxy spectra from P-MaNGA, a prototype of the MaNGA instrument. These data include spectra for eighteen galaxies, covering a large range of morphological type. We derive age, metallicity, dust and stellar mass maps, and their radial gradients, using high spectral-resolution stellar population models, and assess the impact of varying the stellar library input to the models. We introduce a method to determine dust extinction which is able to give smooth stellar mass maps even in cases of high and spatially non-uniform dust attenuation.With the spectral fitting we produce detailed maps of stellar population properties which allow us to identify galactic features among this diverse sample such as spiral structure, smooth radial profiles with little azimuthal structure in spheroidal galaxies, and spatially distinct galaxy sub-components. In agreement with the literature, we find the gradients for galaxies identified as early-type to be on average flat in age, and negative (- 0.15 dex / Re ) in metallicity,whereas the gradients for late-type galaxies are on average negative in age (- 0.39 dex / Re ) and flat in metallicity. We demonstrate howdifferent levels of data quality change the precision with which radialgradients can be measured. We show how this analysis, extended to thelarge numbers of MaNGA galaxies, will have the potential to shed lighton galaxy structure and evolution.PostprintPeer reviewe
A catalogue of open cluster radii determined from Gaia proper motions
In this work we improve a previously published method to calculate in a
reliable way the radius of an open cluster. The method is based on the
behaviour of stars in the proper motion space as the sampling changes in the
position space. Here we describe the new version of the method and show its
performance and robustness. Additionally, we apply it to a large number of open
clusters using data from Gaia DR2 to generate a catalogue of 401 clusters with
reliable radius estimations. The range of obtained apparent radii goes from
Rc=1.4+-0.1 arcmin (for the cluster FSR 1651) to Rc=25.5+-3.5 arcmin (for
NGC~2437). Cluster linear sizes follow very closely a lognormal distribution
with a mean characteristic radius of Rc=3.7 pc, and its high radius tail can be
fitted by a power law as N \propto Rc^(-3.11+-0.35). Additionally, we find that
number of members, cluster radius and age follow the relationship Nc \propto
Rc^(1.2+-0.1) Tc^(-1.9+-0.4) where the younger and more extensive the cluster,
the more members it presents. The proposed method is not sensitive to low
density or irregular spatial distributions of stars and, therefore, is a good
alternative or complementary procedure to calculate open cluster radii not
having previous information on star memberships.Comment: 13 pages including 9 figures and 2 tables (main table will be
available online). Accepted for publication in MNRA
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