A Real-Time Visual Inspection System for Railway Maintenance: Automatic Hexagonal-Headed Bolts Detection

Rail inspection is a very important task in railway maintenance, and it is periodically needed for preventing dangerous situations. Inspection is operated manually by trained human operator walking along the track searching for visual anomalies. This monitoring is unacceptable for slowness and lack of objectivity, as the results are related to the ability of the observer to recognize critical situations. The correspondence presents a patent-pending real-time Visual Inspection System for Railway (VISyR) maintenance, and describes how presence/absence of the fastening bolts that fix the rails to the sleepers is automatically detected. VISyR acquires images from a digital line-scan camera. Data are simultaneously preprocessed according to two discrete wavelet transforms, and then provided to two multilayer perceptron neural classifiers (MLPNCs). The "cross validation" of these MLPNCs avoids (practically-at-all) false positives, and reveals the presence/absence of the fastening bolts with an accuracy of 99.6% in detecting visible bolts and of 95% in detecting missing bolts. A field-programmable gate array-based architecture performs these tasks in 8.09 mus, allowing an on-the-fly analysis of a video sequence acquired at 200 km/h     

Bayesian networks in reliability

Over the last decade, Bayesian networks (BNs) have become a popular tool for modelling many kinds of statistical problems. We have also seen a growing interest for using BNs in the reliability analysis community. In this paper we will discuss the properties of the modelling framework that make BNs particularly well suited for reliability applications, and point to ongoing research that is relevant for practitioners in reliability.     

FraRI: an algorithm to account for the discontinuity at 60° N in MODIS temperature products

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra and Aqua satellites conducts continuous monitoring of the Earth's land surface and oceans. Recently, a sharp discontinuity (averaging 1.9°C) has been noticed at 60° N in both MODIS daytime and night-time land surface temperature (LST) products. This linear artefact arises because the CO₂ high cloud test in the operational code for the generation of the MODIS cloud mask product is used only in the non-polar region (between 60° N and 60° S). The resulting discontinuity clearly has negative implications for any statistical applications of these temperature data. In this technical note we present a new algorithm, which minimizes this discontinuity. The method uses edge detection and elimination based on a mixture of Sobel and non-linear Laplacian filters (edge detection and quantification), cubic splines (edge modelling), and a controllable power function for image restoration. The implementation of this algorithm is demonstrated on an image of average minimum night-time LST between 2001 and 2008.     

Case-Base Maintenance in a Multimodal Reasoning System

The definition of suitable case-base maintenance policies is widely recognized as a major key to success for case-based systems; underestimating this issue may lead to systems that either do not fulfill their role of knowledge management and preservation or that do not perform adequately under performance dimensions, namely, computation time and competence and quality of solutions. The goal of this article is to analyze some automatic case-base management strategies in the context of a multimodal architecture combining case-based reasoning and model-based reasoning. We propose and compare two different methodologies, the first one, called replace , is a competence-based strategy aimed at replacing a set of stored cases with the current one, if the latter exhibits an estimated competence comparable with the estimated competence of the considered set of stored cases. The second one, called learning by failure with forgetting (LFF), is based on incremental learning of cases interleaved with off-line processes of forgetting (deleting) cases whose usage does not fulfill specific utility conditions. Results from an extensive experimental analysis in an industrial plant diagnosis domain are reported, showing the usefulness of both strategies with respect to the maintenance of suitable performance levels for the target system.     

The importance of landscape in wine quality perception: An integrated approach using choice-based conjoint analysis and combination-based permutation tests

This work’s aim is to evaluate the importance of landscape in wine quality perception using a novel integrated approach based on two statistical techniques, i.e. choice-based conjoint analysis (Gustafsson et al., 2001) and combination-based permutation tests (Corain and Salmaso, 2004, Pesarin and Salmaso, 2009a). To this end we developed a preference choice experiment which was submitted to a sample of respondents during blind wine tasting meetings. The obtained results allow us to weigh up and emphasise the importance of an attractive landscape to the perception of a finer quality of wine. Indeed, we noticed that associating wine to an image of greater visual impact, i.e. an evocative landscape, induces a significantly higher preference for the tasted wine. Moreover, the integrated application of choice-based conjoint analysis and combination-based permutation tests allows us to identify the specific relationship each market segment has with landscape, price and wine quality.     

Influence of mediator immobilization on the electrochemically assisted microbial dechlorination of trichloroethene (TCE) and cis‐dichloroethene (cis‐DCE)

BACKGROUND: A bioelectrochemical process for trichloroethene (TCE) dechlorination was developed. In this new process, a solid‐state electrode polarized to ?450 mV versus the standard hydrogen electrode (SHE), in combination with a redox mediator (i.e., methyl viologen, MV) is employed as an electron donor for the microbial reductive dechlorination of TCE. In this study we compared the performance of the process with the redox mediator immobilized at the surface of electrodes or dissolved in the bulk liquid, using both a culture highly enriched in Desulfitobacterium spp., capable of dechlorinating TCE to cis‐dichloroethene (cis‐DCE), and a culture highly enriched in Dehalococcoides spp. capable of dechlorinating cis‐DCE to ethene. RESULTS: Short‐term potentiostatic (?450 mV versus SHE) experiments showed that TCE or cis‐DCE was dechlorinated both in the presence of soluble (500 µmol L^?1) and immobilized MV. However, TCE or cis‐DCE dechlorination rates with MV‐modified electrodes were remarkably lower than with soluble MV. Both cultures produced significant amounts of H₂ in the presence of electrically reduced, soluble MV, whereas no H₂ was produced when the mediator was immobilized at the electrode surface, regardless of the potential applied to the electrode, in the range ?425 to ?500 mV versus SHE. CONCLUSIONS: The process, operated with modified electrodes, supports the microbial dechlorination of TCE to ethene. Immobilization not only allows retention of the mediator within the system, but also increases process efficiency by preventing bioelectrochemical H₂ formation. On the other hand, strategies to increase dechlorination rates with modified electrodes need to be developed. Copyright © 2009 Society of Chemical Industry     

Prediction of air and steam leak rate through cracked reinforced concrete panels

The leak rate prediction of air and steam through a cracked concrete wall is an extremely important issue in assessing the safety of a nuclear reactor containment building. Such a problem requires a multidisciplinary approach involving both the non-linear analysis of the structure, and the thermodynamics aspects related to the flow of a gas through a conduit. In the present paper, some of the available leak rate evaluation formulae are reviewed, and an application to the prediction of the leak rate of either dry air or air+steam mixture through a cracked concrete panel is presented. Finally, in order to validate the numerical procedure herein adopted and to give some indication on the relative merit of the different leak rate formulae considered, the results of the numerical application are compared against leak rate values measured during an experimental test carried out at the ISMES laboratory.     

The online Prize-Collecting Traveling Salesman Problem

We study the online version of the Prize-Collecting Traveling Salesman Problem (PCTSP), a generalization of the Traveling Salesman Problem (TSP). In the TSP, the salesman has to visit a set of cities while minimizing the length of the overall tour. In the PCTSP, each city has a given weight and penalty, and the goal is to collect a given quota of the weights of the cities while minimizing the length of the tour plus the penalties of the cities not in the tour. In the online version, cities are disclosed over time. We give a 7/3-competitive algorithm for the problem, which compares with a lower bound of 2 on the competitive ratio of any deterministic algorithm. We also show how our approach can be combined with an approximation algorithm in order to obtain an O(1)-competitive algorithm that runs in polynomial time.