A comparison of CMB- and HLA-based approaches to type I interoperability reference model problems for COTS-based distributed simulation

Commercial-off-the-shelf (COTS) simulation packages (CSPs) are software used by many simulation modellers to build and experiment with models of various systems in domains such as manufacturing, health, logistics and commerce. COTS distributed simulation deals with the interoperation of CSPs and their models. Such interoperability has been classified into six interoperability reference models. As part of an on-going standardisation effort, this paper introduces the COTS Simulation Package Emulator, a proposed benchmark that can be used to investigate Type I interoperability problems in COTS distributed simulation. To demonstrate its use, two approaches to this form of interoperability are discussed, an implementation of the CMB conservative algorithm, an example of a so-called “light” approach, and an implementation of the HLA TAR algorithm, an example of a so-called “heavy” approach. Results from experimentation over four federation topologies are presented and it is shown the HLA approach out performs the CMB approach in almost all cases. The paper concludes that the CSPE benchmark is a valid basis from which the most efficient approach to Type I interoperability problems for COTS distributed simulation can be discovered

Interactivity-Constrained Server Provisioning in Large-Scale Distributed Virtual Environments

Maintaining interactivity is one of the key challenges in distributed virtual environments (DVEs). In this paper, we consider a new problem, termed the interactivity-constrained server provisioning problem, whose goal is to minimize the number of distributed servers needed to achieve a prespecified level of interactivity. We identify and formulate two variants of this new problem and show that they are both NP-hard via reductions to the set covering problem. We then propose several computationally efficient approximation algorithms for solving the problem. The main algorithms exploit dependencies among distributed servers to make provisioning decisions. We conduct extensive experiments to evaluate the performance of the proposed algorithms. Specifically, we use both static Internet latency data available from prior measurements and topology generators, as well as the most recent, dynamic latency data collected via our own large-scale deployment of a DVE performance monitoring system over PlanetLab. The results show that the newly proposed algorithms that take into account interserver dependencies significantly outperform the well-established set covering algorithm for both problem variants

Survey and classification of functional characteristics in neural network technique for the diagnosis of ischemic heart disease: A systematic review

Background: Nowadays, the prevalence of ischemic heart diseases (IHDs) leads to destructive effects such as patient death. Late diagnosis of such diseases as well as their invasive diagnostic approaches made researchers provide a decision support system based on neural network techniques, while using minimum data set for timely diagnosis. In this regard, selecting minimum useful features is significant for designing neural network structure and it paves the way to attain maximum accuracy in obtaining the results. Methods: In this systematic review, valid databases using sensitive keywords were initially searched out to find articles related to "diagnosing the ischemic heart disease using artificial neural networks" and afterwards, scientific methods were used to analyze and classify the content. Findings: Researchers applied various extractable features from demographic data, medical history, signs and symptoms, and paraclinical examinations, to design the neural network structure. Among them, the features obtained from electrocardiographic test, embedded in paraclinical examinations, had led to a remarkable increase of efficiency in neural network. Conclusion: Utilizing such diagnostic decision support systems in practical environments depends on their high confidence coefficient and physicians� acceptability. Therefore, it can be useful to improve maturity in the design of the neural network structure depending on the choice of the minimum optimal features, and to create required infrastructures to input patients� real, accurate, and flowing data in these systems. © 2018, Isfahan University of Medical Sciences(IUMS). All rights reserved

Survey and classification of functional characteristics in neural network technique for the diagnosis of ischemic heart disease: A systematic review

Background: Nowadays, the prevalence of ischemic heart diseases (IHDs) leads to destructive effects such as patient death. Late diagnosis of such diseases as well as their invasive diagnostic approaches made researchers provide a decision support system based on neural network techniques, while using minimum data set for timely diagnosis. In this regard, selecting minimum useful features is significant for designing neural network structure and it paves the way to attain maximum accuracy in obtaining the results. Methods: In this systematic review, valid databases using sensitive keywords were initially searched out to find articles related to "diagnosing the ischemic heart disease using artificial neural networks" and afterwards, scientific methods were used to analyze and classify the content. Findings: Researchers applied various extractable features from demographic data, medical history, signs and symptoms, and paraclinical examinations, to design the neural network structure. Among them, the features obtained from electrocardiographic test, embedded in paraclinical examinations, had led to a remarkable increase of efficiency in neural network. Conclusion: Utilizing such diagnostic decision support systems in practical environments depends on their high confidence coefficient and physicians� acceptability. Therefore, it can be useful to improve maturity in the design of the neural network structure depending on the choice of the minimum optimal features, and to create required infrastructures to input patients� real, accurate, and flowing data in these systems. © 2018, Isfahan University of Medical Sciences(IUMS). All rights reserved

Nova Cygni 2001/2 = V2275 Cyg

We present an analysis of low- and medium resolution spectra of the very fast nova, Nova Cygni 2001/2 (V2275 Cyg) obtained at nine epochs in August, September and October, 2001. The expansion velocity from hydrogen Balmer lines is found to be 2100 km/s, although early H-alpha profile showed a weak feature at -3500 km/s, too. The overall appearance of the optical spectrum is dominated by broad lines of H, He and N, therefore, the star belongs to the ``He/N'' subclass of novae defined by Williams (1992). Interstellar lines and bands, as well as BV photometry taken from the literature yielded to a fairly high reddening of E(B-V)=1.0+/-0.1 mag. The visual light curve was used to deduce M_V by the maximum magnitude versus rate of decline relationship. The resulting parameters are: t_0=2452141.4(+0.1)(-0.5), t_2=2.9+/-0.5 days, t_3=7+/-1 days, M_V=-9.7+/-0.7 mag. Adopting these parameters, the star lies between 3 kpc and 8 kpc from the Sun.Comment: 5 pages, 5 figures, accepted for publication in A&

Near-infrared Observations of Nova V574 Puppis (2004)

We present results obtained from extensive near-infrared spectroscopic and photometric observations of nova V574 Pup during its 2004 outburst. The observations were obtained over four months, starting from 2004 November 25 (four days after the nova outburst) to 2005 March 20. The near-IR JHK light curve is presented - no evidence is seen from it for dust formation to have occurred during our observations. In the early decline phase, the JHK spectra of the nova are dominated by emission lines of hydrogen Brackett and Paschen series, OI, CI and HeI. We also detect the fairly uncommon Fe II line at 1.6872 micron in the early part of our observations. The strengths of the HeI lines at 1.0830 micron and 2.0585 micron are found to become very strong towards the end of the observations indicating a progression towards higher excitation conditions in the nova ejecta. The width of the emission lines do not show any significant change during the course of our observations. The slope of the continuum spectrum was found to have a lambda^{-2.75} dependence in the early stages which gradually becomes flatter with time and changes to a free-free spectral dependence towards the later stages. Recombination analysis of the HI lines shows deviations from Case B conditions during the initial stages. However, towards the end of our observations, the line strengths are well simulated with case B model values with electron density n_e = 10^{9-10} cm^{-3} and a temperature equal to 10^4 K. Based on our distance estimate to the nova of 5.5 kpc and the observed free-free continuum emission in the later part of the observations, we estimate the ionized mass of the ejecta to be between 10^{-5} and 10^{-6} solar-mass.Comment: 10 pages, 8 figures, Accepted for publication in MNRA

Observation of the first gravitational microlensing event in a sparse stellar field : the Tago event

We report the observation of the first gravitational microlensing event in a sparse stellar field, involving the brightest (V=11.4 mag) andclosest (~ 1 kpc) source star to date. This event was discovered by an amateurastronomer, A. Tago, on 2006 October 31 as a transient brightening, by ~4.5 mag during a ~15 day period, of a normal A-type star (GSC 3656-1328) in the Cassiopeia constellation. Analysis of both spectroscopic observations and the light curve indicates that this event was caused by gravitational microlensing rather than an intrinsically variable star. Discovery of this single event over a 30 year period is roughly consistent with the expected microlensing rate for the whole sky down to V = 12 mag stars. However, the probability for finding events with such a high magnification (~ 50) is much smaller, by a factor ~1/50, which implies that the true event rate may be higher than expected. This discovery indicates the potential of all sky variability surveys, employing frequent sampling by telescopes with small apertures and wide fields of view, for finding such rare transient events, and using the observations to explore galactic disk structure and search for exo-planets.Comment: 13 pages, 2 tables, 3 figures, accepted by Ap

On the Progenitor System of Nova V2491 Cygni

Nova V2491 Cyg is one of just two detected pre-outburst in X-rays. The light curve of this nova exhibited a rare "re-brightening" which has been attributed by some as the system being a polar, whilst others claim that a magnetic WD is unlikely. By virtue of the nature of X-ray and spectroscopic observations the system has been proposed as a recurrent nova, however the adoption of a 0.1 day orbital period is generally seen as incompatible with such a system. In this research note we address the nature of the progenitor system and the source of the 0.1 day periodicity. Through the combination of Liverpool Telescope observations with published data and archival 2MASS data we show that V2491 Cyg, at a distance of 10.5 - 14 kpc, is likely to be a recurrent nova of the U Sco-class; containing a sub-giant secondary and an accretion disk, rather than accretion directly onto the poles. We show that there is little evidence, at quiescence, supporting a ~ 0.1 day periodicity, the variation seen at this stage is likely caused by flickering of a re-established accretion disk. We propose that the periodicity seen shortly after outburst is more likely related to the outburst rather than the - then obscured - binary system. Finally we address the distance to the system, and show that a significantly lower distance (~ 2 kpc) would result in a severely under-luminous outburst, and as such favour the larger distance and the recurrent nova scenario.Comment: 5 pages, 3 images, accepted for publication in A&A as a research not

Graphene catalyzes the reversible formation of a C–C bond between two molecules

Carbon deposits are well-known inhibitors of transition metal catalysts. In contrast to this undesirable behavior, here we show that epitaxial graphene grown on Ru(0001) promotes the reversible formation of a C–C bond between −CH2CN and 7,7,8,8-tetracyano-p-quinodimethane (TCNQ). The catalytic role of graphene is multifaceted: First, it allows for an efficient charge transfer between the surface and the reactants, thus favoring changes in carbon hybridization; second, it holds the reactants in place and makes them reactive. The reaction is fully reversible by injecting electrons with an STM tip on the empty molecular orbitals of the product. The making and breaking of the C–C bond is accompanied by the switching off and on of a Kondo resonance, so that the system can be viewed as a reversible magnetic switch controlled by a chemical reactionJ.J.N., F.C., R.M., and A.L.V.d.P. acknowledge the Ministerio de Economía y Competitividad (MINECO) project FIS2015-67367-C2-1-P and Comunidad de Madrid projects MAD2D P2013/MIT-3007 and Nanofrontmag S2013/MIT-2850. M.P., C.D., and F.M. acknowledge the MINECO project FIS2016-77889-R and computer time from the CCC-UAM and the Red Española de Supercomputación. C.D. acknowledges a Ramón y Cajal contract from MINECO (Spain). E.M.P., J.V., and B.N.-O. acknowledge the European Research Council project MINT, ERC-StG-2012-307609. IMDEA Nanoscience acknowledges support from the “Severo Ochoa” Programme for Centres of Excellence in R&D (MINECO, grant SEV-2016-0686). IFIMAC acknowledges support from the “María de Maeztu” Programme for Units of Excellence in R&D (MDM-2014-0377