Search results for "fault"

ATLAS technical coordination expert system

2019

When planning an intervention on a complex experiment like ATLAS, the detailed knowledge of the system under intervention and of the interconnection with all the other systems is mandatory. In order to improve the understanding of the parties involved in an intervention, a rule-based expert system has been developed. On the one hand this helps to recognise dependencies that are not always evident and on the other hand it facilitates communication between experts with different backgrounds by translating between vocabularies of specific domains. To simulate an event this tool combines information from different areas such as detector control (DCS) and safety (DSS) systems, gas, cooling, vent…

Reliability Analysis of Systems Containing Complex Control Loops

1986

Abstract Many Process Plants employ complex control and trip systems to improve process safety. Reliability prediction requires determination of the failure mechanisms followed by quantification of the failure rates. The fault tree technique is often used for reliability prediction. Fault tree construction is a skilled task and can be complex for systems containing multiple protective devices. The paper compares 3 approaches to the problem of fault tree construction. The problems of quantification and common mode failure is also considered.

Epistemic uncertainty in fault tree analysis approached by the evidence theory

2012

Abstract Process plants may be subjected to dangerous events. Different methodologies are nowadays employed to identify failure events, that can lead to severe accidents, and to assess the relative probability of occurrence. As for rare events reliability data are generally poor, leading to a partial or incomplete knowledge of the process, the classical probabilistic approach can not be successfully used. Such an uncertainty, called epistemic uncertainty, can be treated by means of different methodologies, alternative to the probabilistic one. In this work, the Evidence Theory or Dempster–Shafer theory (DST) is proposed to deal with this kind of uncertainty. In particular, the classical Fau…

TREEZZY2, a Fuzzy Logic Computer Code for Fault Tree and Event Tree Analyses

2004

In conventional approach to reliability analysis using logical trees methodologies, uncertainties in system components or basic events failure probabilities are approached by assuming probability distribution functions. However, data are often insufficient for statistical estimation, and therefore it is required to resort to approximate estimations. Moreover, complicate calculations are needed to propagate uncertainties up to the final results. In our work, in order to take account of the uncertainties in system failure probabilities, the methodology based on fuzzy sets theory is used both in fault tree and event tree analyses. This paper just presents our work in this issue, which resulted…

Risk Assessment and Analysis

2014

Once threats are identified, they must be assessed or evaluated, which is the objective of this chapter. There is usually a large number of threats, making it impossible or unprofitable to analyze them all, meaning selection of the threats that will be addressed is important. It is a decision-making process; an example is proposed and solved by one of the many techniques available. The chapter proposes a very standard requested study, which is the assessment of the economic and financial risks of a project. This is done through a real-life-example, followed by another appraisal, this time devoted to economic issues, as well as another for transportation, introducing the important concept of…

A New Approach for the Reliability of Vehicular Ad Hoc Networks

2018

Vehicular ad hoc networks (VANET), a subset of Mobile Ad hoc Networks (MANETs), is a wireless communication technology applied to transportation, referring to a set of smart vehicles used on the road. These vehicles provide communication services among one another (V2V) or with Road Side Infrastructure (V2I). The main benefits of VANET are enhancing road safety, reducing energy use and emissions, and giving information services. Reliability is one of the most critical issues related to VANET since the information transmitted is distributed in an open access environment. We focused in this paper, on the reliability of VANET as a function of reliable hardware and their functionality taking in…

Enzyme contribution of non-Saccharomyces yeasts to wine production

2015

The fermentation of grape must to produce wine is a biologically complex process, carried on by yeasts and malolactic bacteria. The yeasts present in spontaneous fermentation may be divided into two groups, the Saccharomyces yeasts, particularly S. cerevisiae, and the non-Saccharomyces yeasts which include members of the genera Rhodotorula, Pichia, Candida, Debaryomyces, Metschtnikowia, Hansenula and Hanseniaspora. S. cerevisiae yeasts are able to convert sugar into ethanol and CO2 via fermentation. They have been used for thousands of years by mankind for the production of fermented beverages and foods, including wine. Their enzymes provide interesting wine organoleptic characteristics. β-…

Biogenic amine determination in wine fermented in oak barrels: Factors affecting formation

2008

Changes in biogenic amines (histamine, putrescine, tyramine and cadaverine) were monitored during the industrial production of Tempranillo and Cabernet Sauvignon wines. The origin of these amines in relation to the presence of different lactic bacteria (indigenous or inoculated) during malolactic fermentation, while aging in oak barrel, and the correlations between amines and their corresponding amino acids were statistically evaluated. In this study we found that there was a greater increase in amines post malic acid depletion than during malolactic fermentation and that more amines were produced in wine of the Tempranillo variety. The total amino acid concentration was 1.6 times greater i…

Principal Parameters of Grape Ripening and Wine Fermentation

2008

Current signature based fault diagnosis of field-oriented and direct torque-controlled induction motor drives

2017

In this article, the operation of three-phase squirrel-cage induction motors is analysed under faulty conditions in closed loop with state-of-the-art controllers, namely, the field-oriented control...