Online Fault Classification in HPC Systems through Machine Learning

As High-Performance Computing (HPC) systems strive towards the exascale goal, studies suggest that they will experience excessive failure rates. For this reason, detecting and classifying faults in HPC systems as they occur and initiating corrective actions before they can transform into failures will be essential for continued operation. In this paper, we propose a fault classification method for HPC systems based on machine learning that has been designed specifically to operate with live streamed data. We cast the problem and its solution within realistic operating constraints of online use. Our results show that almost perfect classification accuracy can be reached for different fault types with low computational overhead and minimal delay. We have based our study on a local dataset, which we make publicly available, that was acquired by injecting faults to an in-house experimental HPC system.Comment: Accepted for publication at the Euro-Par 2019 conferenc

Cosmic ray spectral hardening due to dispersion in the source injection spectra

Recent cosmic ray (CR) experiments discovered that the CR spectra experience a remarkable hardening for rigidity above several hundred GV. We propose that this is caused by the superposition of the CR energy spectra of many sources that have a dispersion in the injection spectral indices. Adopting similar parameters as those of supernova remnants derived from the Fermi $\gamma$-ray observations, we can reproduce the observational CR spectra of different species well. This may be interpreted as evidence to support the supernova remnant origin of CRs below the knee. We further propose that the same mechanism may explain the "ankle" of the ultra high energy CR spectrum.Comment: 5 pages, 3 figures and 1 table. Updated with the diffusion propagation model, accepted by Phys. Rev.

Cosmic-ray propagation properties for an origin in SNRs

We have studied the impact of cosmic-ray acceleration in SNR on the spectra of cosmic-ray nuclei in the Galaxy using a series expansion of the propagation equation, which allows us to use analytical solutions for part of the problem and an efficient numerical treatment of the remaining equations and thus accurately describes the cosmic-ray propagation on small scales around their sources in three spatial dimensions and time. We found strong variations of the cosmic-ray nuclei flux by typically 20% with occasional spikes of much higher amplitude, but only minor changes in the spectral distribution. The locally measured spectra of primary cosmic rays fit well into the obtained range of possible spectra. We further showed that the spectra of the secondary element Boron show almost no variations, so that the above findings also imply significant fluctuations of the Boron-to-Carbon ratio. Therefore the commonly used method of determining CR propagation parameters by fitting secondary-to-primary ratios appears flawed on account of the variations that these ratios would show throughout the Galaxy.Comment: Accepted for publication in Ap

As representações sociais sobre a reforma agrária popular nas mídias digitais do Movimento dos Trabalhadores Rurais Sem Terra (MST)

avanço da internet e das mídias digitais torna o ciberespaço em um novo canal de comunicação e informação. Dessa forma, várias organizações e movimentos populares de luta por direitos, cidadania e mudanças sociais se apropriem desse espaço para troca de ideias e produção de conhecimento no contexto da esfera pública virtual. As mídias digitais ampliam a circulação das representações sociais sobre os espaços rurais e seus agentes sociais, como é o caso dos movimentos populares de luta pela terra e reforma agrária no Brasil, pois estes passam a exercer um papel de mediação, ampliando o ambiente do debate público, anteriormente concentrado nas mídias tradicionais monopolizadas. O que possibilita uma expansão em relação às discussões sobre as demandas de direitos e os discursos acerca da questão agrária nas mídias digitais. Nesse sentido, esse estudo analisa quais as representações sobre o projeto de Reforma Agrária Popular do Movimento dos Trabalhadores Rurais Sem Terra (MST) que circulam nas mídias digitais deste Movimento. Partimos de uma perspectiva teórica da Teoria das Representações Sociais (TRS), enfatizando seu caráter mediador no debate contemporâneo sobre os usos e as apropriações das mídias digitais pelos movimentos populares nos espaços rurais, na luta por direitos sociais e busca de cidadania. Apresentamos debate sobre a construção de uma nova cidadania no Brasil, a luta por cidadania comunicativa e as potencialidades das mídias digitais na ampliação da visibilidade pública dos movimentos populares na esfera pública virtual Realizamos ainda análise contextual sobre a problemática da questão agrária brasileira, a formação histórica do MST, bem como seu papel político no país e as características do processo de comunicação popular dessa organização. A abordagem metodológica fundamenta-se na Análise de Conteúdo, para a investigação textual do conteúdo informativo e análise dos dados e informações coletadas nas entrevistas. Utilizamos a técnica de entrevista com comunicadores e lideranças do MST. A pesquisa qualitativa on-line foi realizada para coleta de conteúdos informativos de duas páginas virtuais da organização e de formulação de mapas representacionais, a partir da análise da ancoragem e objetivação das representações sociais. O estudo de caráter qualitativo analisa os conteúdos informativos em publicações, nas páginas on-line especiais da Feira Nacional da Reforma Agrária do MST, de 2015, e na Jornada Nacional de Luta pela Reforma Agrária do MST, de 2016. Conclui-se que as principais representações sociais sobre a Reforma Agrária Popular do MST apresentam este como um movimento político, que a partir da sua luta social transforma as áreas de assentamentos em produtores de alimentos para o abastecimentos dos centros urbanos. Ampliando a função da reforma agrária e buscando transformá-la em um projeto alternativo e sustentável para o desenvolvimento do campo.The advancement of the Internet and digital media turns the cyberspace into a new channel for communication and information. In this way, various organizations and popular civil rights movements take over this space in order to exchange ideas and produce knowledge on the virtual public sphere. The digital media broadens the circulation of rural spaces and their social agents' social representations, like the people's movements fighting for land and agrarian reform in Brazil, as they begin to play a mediating role, broadening the public debate conditions, which were previously focused on the traditional monopolized media. This enables an expansion of discussions regarding civil rights demands and dialogues about the agrarian issue, in the digital media. In this sense, this study analyzes which representations on the Landless Rural Workers Movement's (MST) Popular Agrarian Reform project circulate on its digital media. We set off with a theoretical perspective from the Social Representations' Theory (TRS), emphasizing its mediating character to the contemporary debate on the uses and appropriations of digital media by popular movements in rural areas fighting for social rights and pursuing citizenship. We present a debate about the construction of a new citizenship in Brazil, the struggle for communicative citizenship and the potential of digital media in broadening the public visibility of popular movements in the virtual public sphere. We also perform a contextual analysis on the problems of the Brazilian agrarian issue, the MST's historical formation, as well as its political role in the country and on this organization's characteristics of the popular communication process The methodological approach is based on Content Analysis, in order to elaborate a textual research of the content and to analyze all the data and information collected during the interviews. We employed an interview technique with MST communicators and leaders. On-line qualitative research was carried out to collect informative contents of two of the organization's virtual pages and to formulate representative maps, based on the analysis of the social representations' progress and objectification. The qualitative study analyzes the information content in publications in the special online pages of the MST's National Land Reform Fair, in 2015, and in the MST's Fight for Land Reform's National Working Day, in 2016. It is concluded that the main social representations on the MST's Popular Agrarian Reform show it as a political movement, which, from its social struggle, transforms settlements areas into food producers to supply the urban centers. To this extent, being able to extend the agrarian reform function and seek to transform it into an alternative and sustainable project for the development of the farmlands

1064 nm rotational Raman lidar for particle extinction and lidar-ratio profiling: cirrus case study

For the first time, vertical profiles of the 1064 nm particle extinction coefficient obtained from Raman lidar observations at 1058 nm (nitrogen and oxygen rotational Raman backscatter) are presented. We applied the new technique in the framework of test measurements and performed several cirrus observations of particle backscatter and extinction coefficients, and corresponding extinction-to-backscatter ratios at the wavelengths of 355, 532, and 1064 nm. The cirrus backscatter coefficients were found to be equal for all three wavelengths keeping the retrieval uncertainties in mind. The multiple-scattering-corrected cirrus extinction coefficients at 355 nm were on average about 20–30 % lower than the ones for 532 and 1064 nm. The cirrus-mean extinction-to-backscatter ratio (lidar ratio) was 31 ± 5 sr (355 nm), 36 ± 5 sr (532 nm), and 38 ± 5 sr (1064 nm) in this single study. We further discussed the requirements needed to obtain aerosol extinction profiles in the lower troposphere at 1064 nm with good accuracy (20 % relative uncertainty) and appropriate temporal and vertical resolution

Depolarization and lidar ratios at 355, 532, and 1064 nm and microphysical properties of aged tropospheric and stratospheric Canadian wildfire smoke

We present spectrally resolved optical and microphysical properties of western Canadian wildfire smoke observed in a tropospheric layer from 5-6.5 km height and in a stratospheric layer from 15-16 km height during a recordbreaking smoke event on 22 August 2017. Three polarization/ Raman lidars were run at the European Aerosol Research Lidar Network (EARLINET) station of Leipzig, Germany, after sunset on 22 August. For the first time, the linear depolarization ratio and extinction-to-backscatter ratio (lidar ratio) of aged smoke particles were measured at all three important lidar wavelengths of 355, 532, and 1064 nm. Very different particle depolarization ratios were found in the troposphere and in the stratosphere. The obviously compact and spherical tropospheric smoke particles caused almost no depolarization of backscattered laser radiation at all three wavelengths ( 500nm). The stratospheric smoke particles formed a pronounced accumulation mode (in terms of particle volume or mass) centered at a particle radius of 350-400 nm. The effective particle radius was 0.32 μm. The tropospheric smoke particles were much smaller (effective radius of 0.17 μm). Mass concentrations were of the order of 5.5 μgm-3 (tropospheric layer) and 40 μgm-3 (stratospheric layer) in the night of 22 August 2017. The single scattering albedo of the stratospheric particles was estimated to be 0.74, 0.8, and 0.83 at 355, 532, and 1064 nm, respectively

Galactic Cosmic Rays from Supernova Remnants: II Shock Acceleration of Gas and Dust

This is the second paper (the first was astro-ph/9704267) of a series analysing the Galactic Cosmic Ray (GCR) composition and origin. In this we present a quantitative model of GCR origin and acceleration based on the acceleration of a mixture of interstellar and/or circumstellar gas and dust by supernova remnant blast waves. We present results from a nonlinear shock model which includes (i) the direct acceleration of interstellar gas-phase ions, (ii) a simplified model for the direct acceleration of weakly charged dust grains to energies of order 100keV/amu simultaneously with the gas ions, (iii) frictional energy losses of the grains colliding with the gas, (iv) sputtering of ions of refractory elements from the accelerated grains and (v) the further shock acceleration of the sputtered ions to cosmic ray energies. The calculated GCR composition and spectra are in good agreement with observations.Comment: to appear in ApJ, 51 pages, LaTeX with AAS macros, 9 postscript figures, also available from ftp://wonka.physics.ncsu.edu/pub/elliso