Area classification for explosive atmospheres: comparison between European and North American approaches

The object of this paper is to review various methods of determining the extent of hazardous areas in industrial facilities where explosive gas or vapor atmospheres may be present. Three different approaches are analyzed and compared. The first one is recommended in North American Standards, such as API500, API505 and NFPA 497. The second is one of the proposals for the second edition of the International Standard IEC 60079-10-1 (adopted as European standard EN 60079-10-1). The third approach had been previously worked out with the authors‘ contribution and had been adopted by the Italian Guide CEI 31-35 since 2001. The last two approaches are analytical, meanwhile the first one is prescriptive. In the second part of the paper both analytical approaches are applied to the releases which are analyzed in NFPA 497 as practical examples. Resulting hazardous area extents are compared and the differences among the three methods are discusse

Hazardous areas extension in explosive atmospheres caused by free gas jets

This paper regards the validation procedure of the Italian Guide CEI 31-35 formula, used to calculate the hazardous areas extensions in places where explosive gas atmospheres may be present. In industrial activity, a typical event which cause explosive atmosphere consists of damaging and leakage from unions, gaskets, valves of pipes and vessels. At this purpose, in this work it has been taken into account the accidental discharge of flammable gas into a quiescent atmosphere through an orifice. Validation has been performed by comparing calculated values with experimental data. Two gases have been taken into account: methane and hydrogen. Different scenarios have been analyzed, each one differing from the others in the gas release cross section and in the vessel pressure. Results show that the formula fits well not catastrophic industrial accident situation

Effective Aggregation and Querying of Probabilistic RFID Data in a Location Tracking Context

RFID applications usually rely on RFID deployments to manage high-level events such as tracking the location that products visit for supply-chain management, localizing intruders for alerting services, and so on. However, transforming low-level streams into high-level events poses a number of challenges. In this paper, we deal with the well known issues of data redundancy and data-information mismatch: we propose an on-line summarization mechanism that is able to provide small space representation for massive RFID probabilistic data streams while preserving the meaningfulness of the information. We also show that common information needs, i.e. detecting complex events meaningful to applications, can be effectively answered by executing temporal probabilistic SQL queries directly on the summarized data. All the techniques presented in this paper are implemented in a complete framework and successfully evaluated in real-world location tracking scenarios

Approximating expressive queries on graph-modeled data: The GeX approach

We present the GeX (Graph-eXplorer) approach for the approximate matching of complex queries on graph-modeled data. GeX generalizes existing approaches and provides for a highly expressive graph-based query language that supports queries ranging from keyword-based to structured ones. The GeX query answering model gracefully blends label approximation with structural relaxation, under the primary objective of delivering meaningfully approximated results only. GeX implements ad-hoc data structures that are exploited by a top-k retrieval algorithm which enhances the approximate matching of complex queries. An extensive experimental evaluation on real world datasets demonstrates the efficiency of the GeX query answering

Thallium contamination in the Raibl Mine Site stream drainage system (Eastern Alps, Italy)

The Raibl mine (Cave del Predil village, northern Italy) belongs to the Pb–Zn minerogenetic district in the southeastern Alps, hosted in Middle Triassic carbonates. The drainage water quality reflects the high acid-buffering capacity of the carbonate rocks, which controls the mobility of most metals. In particular, Fe is non-detectable in solution, having formed hydrous-oxides precipitates. Molybdenum, Ni, Zn, Cd, Pb, and Tl are present, and the Pb, Tl, and Zn concentrations sometimes exceed the Italian regulatory thresholds. Thallium concentrations substantially exceed the 2 µg/L limit at some sampling stations, ranging between 12 and 30 µg/L in the mine drainage, and reaching 5 µg/L downstream of the mine site, despite strong dilution. The data indicate that Tl behaves almost conservatively and is not significantly scavenged by the Fe precipitates. The elevated Tl represents a potential risk for the stream ecosystem. Although Tl is not regulated in drinking water in Italy or the European Community, its distribution in natural waters may help to determine if health actions should be taken

On the role of synaptic stochasticity in training low-precision neural networks

Stochasticity and limited precision of synaptic weights in neural network models are key aspects of both biological and hardware modeling of learning processes. Here we show that a neural network model with stochastic binary weights naturally gives prominence to exponentially rare dense regions of solutions with a number of desirable properties such as robustness and good generalization performance, while typical solutions are isolated and hard to find. Binary solutions of the standard perceptron problem are obtained from a simple gradient descent procedure on a set of real values parametrizing a probability distribution over the binary synapses. Both analytical and numerical results are presented. An algorithmic extension aimed at training discrete deep neural networks is also investigated.Comment: 7 pages + 14 pages of supplementary materia

A Preliminary Color Study of Different Basil-Based Semi-Finished Products during Their Storage

open6: Basil-based semi-finished products, which are mainly used as an intermediate to produce the typical pesto sauce, are prepared and exported all over the world. Color is a fundamental organoleptic requirement for the acceptability of these semi-finished products by the manufacturers of the pesto sauce. Some alternative formulations, which adjust the typical industrial recipe by both changing the preservative agent (ascorbic acid, citric acid, or a mixture of both) and introducing a preliminary thermic treatment (blast chilling), were evaluated. In this work, a fast and non-destructive spectrophotometric analysis, to monitor the color variations in these food products during their shelf-life, was proposed. The raw diffuse reflectance spectra (380–900 nm) obtained by a UV–visible spectrophotometer, endowed with an integrating sphere, together with the CIELab parameters (L*, a*, b*) automatically obtained from these, were considered, and elaborated using multivariate statistical analysis (principal component analysis). From this preliminary study, blast chilling, together with the use of ascorbic acid, proved to be the best solution to better preserve the color of these products during their shelf-life.openTurrini, Federica; Farinini, Emanuele; Leardi, Riccardo; Grasso, Federica; Orlandi, Valentina; Boggia, Raffaella;Turrini, Federica; Farinini, Emanuele; Leardi, Riccardo; Grasso, Federica; Orlandi, Valentina; Boggia, Raffaell