Search results for "fault"

A New Protection Strategy for Electrical Distribution Systems

2010

In this paper, the authors propose a new protection strategy for electrical Medium Voltage distribution networks, based on a distributed intelligence system composed of a central unit and of many local processing units. The distributed intelligence system can precisely identify and locate faults in suitably limited times. Each local processing unit is composed of a data acquisition system and a data analysis system. The first allows the accurate reconstruction of the fundamental using only 1.5 cycles of under fault transient electrical quantities. The second performs suitably precise on-line fault diagnosis based on the data provided by the data acquisition module. The data acquisition algo…

DESIGN OF A FAULT AND PARTIAL DISCHARGES LOCATION DEVICE FOR CABLE POWER NETWORK

In this thesis, a digital device for fault and on line partial discharge location is presented. The device employs the traveling wave method for two or multiple ends. The designed prototype shows interesting features connected to the low cost and to the possibility to collect data from different locations thus providing additional functionalities deriving from pre-fault and data analysis, relating the existence of defects to the subsequent fault event. The device also enables the acquisition of the temperature on the cable section where the sensor is installed. Such installation can also support DSO and TSO for carrying out both on-event and condition based maintenance, discovering the caus…

Performance of LoRa technology: link-level and cell-level performance

2020

Abstract LoRa is a chirp spread spectrum technology that is becoming very popular for low-power wide-area networks, with high-density devices. In this chapter, we study the capacity of LoRa in rejecting different interfering signals. First, we analyze LoRa modulation numerically demonstrating that channel captures appear easily and that collisions between packets modulated with different spreading factors (SFs) are not uncommon. We validate such findings in experiments based on commercial devices and software-defined radios. Second, we model the network capacity obtainable in a typical LoRa cell: we show that high SFs can be seriously influenced by inter-SF collisions and that fading has a …

BioAnalysis: A Framework for Structural and Functional Robustness Analysis of Metabolic Networks

2010

The main objective of this work is to analyze metabolic networks evolution in terms of their robustness and fault tolerance capabilities. In metabolic networks, errors can be seen as random removal of network nodes, while attacks are high-connectivity-degree node deletion aimed at compromising network activity. This paper proposes a software framework, namely BioAnalysis, used to test the robustness and the fault tolerance capabilities of real metabolic networks, when mutations and node deletions affect the network structure. The performed simulations are related to the central metabolic network of the well-known E. coli single-celled bacterium and involve either hub nodes or non-hub nodes,…

METABOLIC NETWORKS ROBUSTNESS: THEORY, SIMULATIONS AND RESULTS

2011

Metabolic networks are composed of several functional modules, reproducing metabolic pathways and describing the entire cellular metabolism of an organism. In the last decade, an enormous interest has grown for the study of tolerance to errors and attacks in metabolic networks. Studies on their robustness have suggested that metabolic networks are tolerant to errors, but very vulnerable to targeted attacks against highly connected nodes. However, many findings on metabolic networks suggest that the above classification is too simple and imprecise, since hub node attacks can be by-passed if alternative metabolic paths can be exploited. On the contrary, non-hub nodes attacks can affect cell …

FAULT DETECTION AND DATA PREDICTION FOR WIRELESS SENSOR NETWORKS

2014

In the last few years, Wireless Sensor Networks (WSNs) have been extensively used as a pervasive sensing module of Ambient Intelligence (AmI) systems in several application fields, thanks to their versatility and ability to monitor diverse environmental quantities. Although wireless sensor nodes are able to perform onboard computations and to share the sensed data, they are limited by the scarcity of energy resources which heavily influences the network lifetime; moreover, the design phase of a WSN requires testing the application scalability prior to actual deployment. In this regard, this dissertation focuses on data prediction to address such crucial tasks as prolonging the network lifet…

Modeling and Verification of Symbolic Distributed Applications Through an Intelligent Monitoring Agent

2022

Wireless Sensor Networks (WSNs) represent a key component in emerging distributed computing paradigms such as IoT, Ambient Intelligence, and Smart Cities. In these contexts, the difficulty of testing, verifying, and monitoring applications in their intended scenarios ranges from challenging to impractical. Current simulators can only be used to investigate correctness at source code level and with limited accuracy. This paper proposes a system and a methodology to model and verify symbolic distributed applications running on WSNs. The approach allows to complement the distributed application code at a high level of abstraction in order to test and reprogram it, directly, on deployed network…

A distributed Bayesian approach to fault detection in sensor networks

2012

Sensor networks are widely used in industrial and academic applications as the pervasive sensing module of an intelligent system. Sensor nodes may occasionally produce incorrect measurements due to battery depletion, dust on the sensor, manumissions and other causes. The aim of this paper is to develop a distributed Bayesian fault detection algorithm that classifies measurements coming from the network as corrupted or not. The computational complexity is polynomial so the algorithm scales well with the size of the network. We tested the approach on a synthetic dataset and obtained significant results in terms of correctly labeled measurements.

QoS-Aware Fault Detection in Wireless Sensor Networks

2013

Wireless sensor networks (WSNs) are a fundamental building block of many pervasive applications. Nevertheless the use of such technology raises new challenges regarding the development of reliable and fault-tolerant systems. One of the most critical issues is the detection of corrupted readings amidst the huge amount of gathered sensory data. Indeed, such readings could significantly affect the quality of service (QoS) of the WSN, and thus it is highly desirable to automatically discard them. This issue is usually addressed through “fault detection” algorithms that classify readings by exploiting temporal and spatial correlations. Generally, these algorithms do not take into account QoS re…

Adaptive distributed outlier detection for WSNs.

2014

The paradigm of pervasive computing is gaining more and more attention nowadays, thanks to the possibility of obtaining precise and continuous monitoring. Ease of deployment and adaptivity are typically implemented by adopting autonomous and cooperative sensory devices; however, for such systems to be of any practical use, reliability and fault tolerance must be guaranteed, for instance by detecting corrupted readings amidst the huge amount of gathered sensory data. This paper proposes an adaptive distributed Bayesian approach for detecting outliers in data collected by a wireless sensor network; our algorithm aims at optimizing classification accuracy, time complexity and communication com…