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Cesare, Stefano (author), Dionisio, Sabrina (author), Saponara, Massimiliano (author), Bravo-Berguño, David (author), Massotti, Luca (author), De Teixeira Da Encarnação, J. (author), Christophe, Bruno (author)The Next Generation Gravity Mission (NGGM), currently in a feasibility study phase as a candidate Mission of Opportunity for ESA-NASA cooperation in the frame of the Mass Change and Geo-Sciences International Constellation (MAGIC), is designed to monitor mass transport in the Earth system by its variable gravity signature with increased...journal article 2022
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Cui, Z. (author)This dissertation presents a comprehensive and integrated study, including theory development, numerical simulation and experiment, for multi-physics driven electromigration in microelectronics. Multi-scale methodologies from atomistic modeling to continuum theory-based simulation have been developed. Moreover, extensive experimental testing,...doctoral thesis 2021
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Nunez, Alfredo (author), Jamshidi, A. (author), Wang, H. (author)This paper presents a Pareto-based maintenance decision system for rail welds in a regional railway network. Weld health condition data are collected using a train in operation. A Hilbert spectrum-based approach is used for data processing to detect and assess the weld quality based on multiple registered dynamic responses in the axle box...journal article 2018
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Nunez, Alfredo (author), Popa, Tudor (author), Anghel, Lucian Emmanuel (author), Hendriks, J.M. (author), Moraal, J. (author), Buretea, Laurentiu Dorin (author), Paragreen, Jon (author), Miron, Berbece (author), Gheorghe, Draghici (author), Campean, Mihail (author), Dollevoet, R.P.B.J. (author), Li, Z. (author)In this paper, we present preliminary results on the development of smart technology solutions for lower density railway lines. The goal is to reach a cost effective inspection and asset management to minimize maintenance<br/>interventions time/cost without dedicated inspection vehicles. The proposed methods include axle box acceleration...conference paper 2018
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Nunez, Alfredo (author), Jamshidi, A. (author), Wang, H. (author), Hendriks, J.M. (author), Ramirez Fonseca, I. (author), Moraal, J. (author), Dollevoet, R.P.B.J. (author), Li, Z. (author)In this paper, we propose a methodology based on signal processing and evolutionary multiobjective optimization to facilitate the maintenance decision making of infra-managers in regional railways. Using a train in operation (with passengers onboard), we capture the condition of the rails using Axle Box Acceleration measurements. Then, using...conference paper 2018
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Wei, Z. (author), Nunez, Alfredo (author), Li, Z. (author), Dollevoet, R.P.B.J. (author)In this paper, we investigate the capability of an axle box acceleration (ABA) system to evaluate the degradation at railway crossings. For this purpose, information from multiple sensors, namely, ABA signals, 3D rail profiles, Global Positioning System (GPS) and tachometer recordings, was collected from both nominal and degraded crossings....journal article 2017
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Molodova, M. (author), Oregui Echeverria-Berreyarza, M. (author), Nunez, Alfredo (author), Li, Z. (author), Dollevoet, R.P.B.J. (author)This paper presents a health condition monitoring system for insulated rail joints (IRJs) based on axle box acceleration (ABA) measurements. The ABA signals from all the wheels of the measuring train are processed to extract those characteristics that better represent the quality of the IRJ. Then, different indicators are used for damage...journal article 2016
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Oregui Echeverria-Berreyarza, M. (author), Li, S. (author), Nunez, Alfredo (author), Li, Z. (author), Carroll, R (author), Dollevoet, R.P.B.J. (author)Rail joints are a weak component in railway tracks because of the large impact and wheel-rail contact forces. Every train passage contributes to the deterioration of rail joints, causing visible (e.g. battered rails) and invisible (e.g. loose bolts) damages. The invisible damage cannot be detected by the commonly performed visual inspection,...journal article 2016
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Oregui, M. (author), Molodova, M. (author), Nunez, A. (author), Dollevoet, R.P.B.J. (author), Li, Z. (author)This paper presents a feasibility study to determine if the health condition of Insulated Rail Joints (IRJs) can be assessed by examining their dynamic response to impact excitation. First, a reference dynamic behavior is defined in the frequency domain of 50-1200 Hz based on field hammer test measurements performed on a IRJ baseline (i.e., a...journal article 2015