Search results for "fault"
showing 10 items of 610 documents
Transitivity in coherence-based probability logic
2016
We study probabilistically informative (weak) versions of transitivity by using suitable definitions of defaults and negated defaults in the setting of coherence and imprecise probabilities. We represent p-consistent sequences of defaults and/or negated defaults by g-coherent imprecise probability assessments on the respective sequences of conditional events. Moreover, we prove the coherent probability propagation rules for Weak Transitivity and the validity of selected inference patterns by proving p-entailment of the associated knowledge bases. Finally, we apply our results to study selected probabilistic versions of classical categorical syllogisms and construct a new version of the squa…
Rotor bar pre-fault detection in the squirrel cage induction motors
2015
The paper deals with a diagnosis technique to detect and monitor incipient faults in the rotor bars of squirrel gage induction motors. The failure mode analysis is performed monitoring the motor axial vibrations. To accomplish the task, the authors present a mathematical model that allows relating the occurrence and the severity of the faults to the presence and the magnitude of some frequency components of the axial vibration spectrum. To validate the proposed approach, the results obtained by applying the mathematical model are compared with the ones obtained by experimental tests done on both healthy and faulty motors.
LoneStar RAID
2016
The need for huge storage archives rises with the ever growing creation of data. With today’s big data and data analytics applications, some of these huge archives become active in the sense that all stored data can be accessed at any time. Running and evolving these archives is a constant tradeoff between performance, capacity, and price. We present the LoneStar RAID, a disk-based storage architecture, which focuses on high reliability, low energy consumption, and cheap reads. It is designed for MAID systems with up to hundreds of disk drives per server and is optimized for “write once, read sometimes” workloads. We use dedicated data and parity disks, and export the data disks as individu…
Self-powered IoT Device based on Energy Harvesting for Remote Applications
2018
In this paper, we present the design and prototype implementation of self-powered Internet of Things (IoT) device based on energy harvesting from a small solar panel of size 63mm x 63mm and 0.36W for remote applications. These IoT devices can be deployed in remote places within the range of a gateway. A complete proof of concept IoT device based on ambient energy harvesting is designed, prototyped and tested with super capacitors and Lithium cells in star topology. Based on the measurements, the IoT device can potentially last for one year with 55 seconds transmission interval with the fully charged 120mAh coin cell battery. On the other hand, a fully charged single 5F supercapacitor lasts …
Analysis of the influence of processor hidden registers on the accuracy of fault injection techniques
2004
Modern processors tend to increase the number of registers, being part of them not accessible by the instruction set. Traditionally, the effect of faults in these hidden registers has not been considered during system validation using fault injection. In this paper, a study of the importance of faults in hidden registers is performed. Firstly, we have analysed the sensitivity of hidden registers to faults in combinational logic. In a second phase, we have analysed the impact of the faults occurred in hidden registers on system behaviour. A broad set of permanent and transient faults have been injected into the models of two typical commercial microcontrollers, using a VHDL-based fault injec…
Application of Thermographic Techniques for the Detection of Failures on Photovoltaic Modules
2019
The paper focuses on thermography as a useful investigation tool for diagnosis, detection and prevention of failures of photovoltaic modules. The paper describes the faults detectable by thermographic investigations and how to conduct these investigantions. Then the results of some analyses conducted on a photovoltaic field are presented. The investigations made possible to identify faulty modules with hot spots by measuring localized superheat due to the presence of concentrated deposits on the exposed surface of the module and the superheating due to the presence of sand/dust deposits distributed on a significant portion of the module surface. The thermographic investigations can be used …
Diagnosis of inverter-fed induction motors in short time windows using physics-assisted deep learning framework
2019
This article presents a framework for accurate fault diagnostics in inverter-fed induction machinery operating under variable speed and load conditions within very short time windows. Condition indicators based on fault characteristic frequencies observed over the extended Park's vector modulus are fused with deep features extracted using stacked autoencoders to generate a multidimensional feature space for fault classification using support vector machine. The proposed approach is demonstrated in a laboratory setup to detect the most commonly occurring faults, namely, the stator turns fault, broken rotor bars fault and bearing fault with an accuracy > 98% within a short time window of 2–3 …
An analysis methodology to evaluate the contribution to electrical security given by bare buried conductors in a system of intertied earthing grids
2004
The paper presents an analysis methodology for a single-line-to-ground fault, occurring at a secondary MV/LV substation in a power network formed by a HV/MV station, feeding, through a MV tri-phase cable line, N MV/LV substations whose earth electrodes are interconnected by bare buried conductors. In the preliminary explanation of the methodology, earth buried conductors are studied in their double function of earth electrodes and connection elements between earthing grids, both in absence and in presence of other interfering conductors. Subsequently analyzed is, with a distributed parameters approach, the system constituted by an earth buried conductor and a MV tri-phase cable line. The eq…
Active faults and inferred seismic sources in the San Vito lo Capo peninsula, Northwestern Sicily, Italy.
2006
Two independent active faults, capable of generating medium-sized earthquakes in the San Vito lo Capo peninsula, northwestern Sicily (Italy) have been identified as a result of detailed field studies. In western Sicily, instrumental seismicity is low; in fact, except for the 1968 Belice earthquake (Ms = 5.4), historical records indicate that this area is relatively quiescent. Most of the seismicity is in the offshore sector of the Sicilian Maghrebian Chain, which is characterized by several medium- to low-magnitude events. The main shock of the 2002 Palermo seismic sequence (Mw = 5.9) represents the largest earthquake felt in the area in recent years. The deformation pattern characterizing …
Robust fault detection design for unknown inputs Takagi-Sugeno models with parametric uncertainties and time-varying delays
2014
This paper deals with the design of robust fault detection system for Takagi-Sugeno (T-S) modes with parametric uncertainties and time-varying delay. An Unknown Input Observer (UIO) is designed such that the unknown inputs are thoroughly decoupled from residual signals while they show the maximum possible sensitivity to the faults and the minimum possible sensitivity to the external disturbances. Since the system under consideration is subjected to parametric uncertainties, the H ∞ model matching approach is used to design an optimal observer. Design procedure is given in terms of Linear Matrix Inequalities (LMIs). Finally, a numerical example is presented to show the effectiveness of the p…