1,544 research outputs found
Anomaly Detection using Autoencoders in High Performance Computing Systems
Anomaly detection in supercomputers is a very difficult problem due to the
big scale of the systems and the high number of components. The current state
of the art for automated anomaly detection employs Machine Learning methods or
statistical regression models in a supervised fashion, meaning that the
detection tool is trained to distinguish among a fixed set of behaviour classes
(healthy and unhealthy states).
We propose a novel approach for anomaly detection in High Performance
Computing systems based on a Machine (Deep) Learning technique, namely a type
of neural network called autoencoder. The key idea is to train a set of
autoencoders to learn the normal (healthy) behaviour of the supercomputer nodes
and, after training, use them to identify abnormal conditions. This is
different from previous approaches which where based on learning the abnormal
condition, for which there are much smaller datasets (since it is very hard to
identify them to begin with).
We test our approach on a real supercomputer equipped with a fine-grained,
scalable monitoring infrastructure that can provide large amount of data to
characterize the system behaviour. The results are extremely promising: after
the training phase to learn the normal system behaviour, our method is capable
of detecting anomalies that have never been seen before with a very good
accuracy (values ranging between 88% and 96%).Comment: 9 pages, 3 figure
Empirical Scenarios of Fake Data Analysis: The Sample Generation by Replacement (SGR) Approach
Many self-report measures of attitudes, beliefs, personality, and pathology include items whose responses can be easily manipulated or distorted, as an example in order to give a positive impression to others, to obtain financial compensation, to avoid being charged with a crime, to get a job, or else. This fact confronts both researchers and practitioners with the crucial problem of biases yielded by the usage of standard statistical models.
The current paper presents three empirical applications to the issue of faking of a recent probabilistic perturbation procedure called Sample Generation by Replacement (SGR; Lombardi and Pastore, 2012). With the intent to study the behavior of some statistics under fake perturbation and data reconstruction processes, ad-hoc faking scenarios were implemented and tested. Overall, results proved that SGR could be successfully applied both in the case of research designs traditionally proposed in order to deal with faking (e.g., use of fake-detecting scales, experimentally induced faking, or contrasting applicants vs. incumbents), and in the case of ecological research settings, where no information as regards faking could be collected by the researcher or the practitioner. Implications and limitations are presented and discussed
The balanced scorecard logic in the management control and reporting of small business company networks: a case study
The purpose of this paper is to assess and integrate the application of the balance scorecard (BSC) logic into business networks identifying functions and use that such performance measuring tool may undertake for SME’s collaborative development. Thus, the paper analyses a successful case study regarding an Italian network of small companies, evaluating how the multidimensional perspective of BSC can support strategic and operational network management as well as communication of financial and extra financial performance to stakeholders. The study consists of a qualitative method, proposing the application of BSC model for business networks from international literature. Several meetings and interviews as well as triangulation with primary and secondary documents have been conducted. The case study allows to recognize how BSC network logic can play a fundamental role on defining network mission, supporting management control as well as measuring and reporting the intangible assets formation along the network development lifecycle. This is the first time application of a BSC integrated framework for business networks composed of SMEs. The case study demonstrates operational value of BSC for SME’s collaborative development and success
SPARTINA VERSICOLOR FABRE IN COASTAL AREAS OF TUSCANY (ITALY)
This paper aims to present an overview of Spartina versicolor Fabre populations in the coastal
areas of Tuscany (Italy), in relation to its ecology and phytosociology. Geobotanical surveys were carried out on the
sedimentary coasts along the whole region. Data show that the species grows in embryo dunes, retrodunal sandy
lowlands and surrounding wet areas that are moderately saline. In all cases observed, the species exhibited also a
high sterility and clonal spread. Phytosociological data show different associative behaviours of S. versicolor in
different environment types. In particular it is possible to identify three different phytocoenoses strictly related to the
environmental typologies (dunal, interdunal/retrodunal or wet) and also to soil salinity. In addition, the observations
led us to describe a new subassociation
Starburst Galaxies in Cluster-feeding Filaments Unveiled by Spitzer
We report the first direct detection with Spitzer of galaxy filaments. Using Spitzer and ancillary optical data, we have discovered two filamentary structures in the outskirts of the cluster Abell 1763. Both filaments point toward Abell 1770, which lies at the same redshift as Abell 1763 (z = 0.23), at a projected distance of ~13 Mpc. The X-ray cluster emission is elongated along the same direction. Most of the far-infrared emission is powered by star formation. According to the optical spectra, only one of the cluster members is classified as an active galactic nucleus. Star formation is clearly enhanced in galaxies along the filaments: the fraction of starburst galaxies in the filaments is more than twice than that in other cluster regions. We speculate that these filaments are feeding the cluster Abell 1763 by the infall of galaxies and galaxy groups. Evidence for one of these groups is provided by the analysis of galaxy kinematics in the central cluster region
Ecological and phytosociological aspects of foredune vegetation in a neogenic beach of Tuscany coast (Italy)
An investigation of foredune vegetation of a 2 km long stretch of coast of North West Tuscany (Italy) is conducted. This area has geomorphological features that are very peculiar and different from the rest of the sandy shores of the Tuscan coast. The current beach of about 22 ha, is the result of recent deposits (from the early decades of the last century), derivatives of the production of soda and mainly made from waste carbonate (CaCO3 mainly) that are still discharged into the sea from a chemical factory nearby to the coast. This results in a marked progradation of this stretch of coastline, with a major development of dune vegetation in contrast with neighboring coastal areas. The vegetation analysis and zonation of plant communities show strong anomalies when compared with dune habitats of
the nearby beaches. It has been noted that associations typical of ephemeral and embryonic dune such as Salsolo-Cakiletum and Echinophoro - Elymetum, are almost absent. These characteristic associations have now been replaced with extended surfaces of Sporobolus virginicus and an anomalous distribution of Echinophoro-Ammophiletum. This seems partly due to the significant human interference but also to the particular type of substrate.When human interference is absent and the soil type changes, we see the recovery of normal zonation
Floristic and vegetational characterization of degraded areas in the province of Pisa: the case of a dismissed quarry and the neighboring territory (Municipality of Vecchiano)
The natural restoration of abandoned mining areas is one of the most complex environmental challenges due to the multiplicity of issues involved. In general, the spontaneous dynamics of renaturation in the quarry areas are very slow and altered because of limiting environmental conditions. So, recovery actions should promote ecological processes interrupted by mining and then the acceleration of the natural dynamics. Presently, in the province of Pisa several abandoned quarries have not undergone the necessary environmental recovery and, for this reason, they are classified as "areas of geophysical degradation". These include the former quarry C.E.I. dismissed in 1992 and located on the Monti d’Oltre Serchio in the
municipality of Vecchiano (PI). The present work was focused on the flora and vegetation of this area. The study area, including the quarry (2.9 ha), the remaining sides of the Poggio dei Cavoli and the adjacent ridge of "Sassi Grossi", is characterized by limestone formations of the non metamorphic Tuscan Falda. It is
characterized by a rather hard carsism, with almost no soil and high pH in the quarry area, while it is rich in oxides and lacking humus in the outer portions. Inside the cave, however, the scarcity of vegetation cover and the strong albedo, due to the light-colored rock, cause a different microclimate, characterized by dryness and higher temperature. The flora consists of more than 200 vascular species, of which about 50 are restricted to the quarry and 85 to adjacent areas. Particularly important is the number of floristic emergences, including rare orchids and ferns, which induced some scientists to propose the inclusion of the study area within the Regional Park of Migliarino-San Rossore-Massaciuccoli. This makes the site interesting from an environmental perspective and therefore, worthy of further valorisation and protection. The analysis of aerial photographs and surveys conducted in the field has allowed the identification of the main types of vegetation (Fig. 1). In the territory outside the extraction site, the Mediterranean Macchia (high, medium and low) with evergreen sclerophyllous (Quercion ilicis) in catenal contact with the Garrigue (Rosmarinetalia officinalis and Thero-Brachypodietalia), and the mixed forest with dominant oak and transitional pruneto (referable to the alliance Quercion pubescentis- petraeae Br. Bl. 1931), can be found. The quarry area is, instead, dominated by a pioneer vegetation that is hygrophile on the plain of the quarry, and lithophile on the front. This latter, at least in part, has species in common with the surrounding garrigues. This is interpreted as the initial stage of the series of vegetation that should lead to the reconstitution of the original forest cover, represented by the actual vegetation of the adjacent areas. The widespread presence of species such as Rubus ulmifolius, Clematis vitalba and Dittrichia viscosa (L.) Greuter, and of invasive exotic species, such as Cortaderia selloana, Robinia pseudoacacia, Buddleja davidii and Ailanthus altissima, reveal that, without proper action, it is difficult to imagine a fast around the quarry
The forested agricoltural landscape of Pisdan plain: the Coltano estate
The frequency and coverage of individuals of L. nobilis has reached values over time such as to induce the scientific community and local governments to establish in the northern sector, a nature reserve of about 9 ha called " Forest of laurels ", considered by some authors, one of the few wild and spontaneous stations of Laurus nobilis of peninsular and insular Ital
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