Littérature scientifique sur le sujet « LOCALISED FAULTS »
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Articles de revues sur le sujet "LOCALISED FAULTS"
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Mohamed, E. A., et R. H. Worden. « Groundwater compartmentalisation : a geochemical analysis of the structural controls on the subdivision of a major aquifer, the Sherwood Sandstone, Merseyside, UK ». Hydrology and Earth System Sciences Discussions 2, no 3 (10 juin 2005) : 939–70. http://dx.doi.org/10.5194/hessd-2-939-2005.
Texte intégralRésumé :
Abstract. The study was initiated to assess the local groundwater flow, the extent of seawater invasion and the controls on recharge in the aquifer and to try to understand whether the aquifer is broken into discrete compartments. The study area is located in the northwest of England and encompasses the urban area of Liverpool and surrounding countryside and extends east-west from Liverpool to Widnes and as far north as Formby. The Irish Sea marks the western margin of the area while the Mersey estuary defines the southern margin. The Triassic sandstone in this area has been, and remains, an important aquifer although industrialisation and groundwater exploitation have led to significant water quality problems. Maps of water table for the years 1993, 1997, 2000 and 2002 and schematic cross-sections of the water table height along the faults were prepared to trace any effect of these faults on water table height across. Studying the water table maps and cross sections revealed that: 1) there are substantial differences in water table height across some of the NNW-SSE trending faults implying that groundwater flow is strongly limited by fault, 2) an anticline in the east of the area acts as a groundwater divide and 3) the water table seems to follow the topography in some places, although steep changes in water table occur across faults showings that they locally control the water table elevation. The aquifer was thus provisionally subdivided into several hydrogeological sub-basins based on water table height patterns and the occurrence of major structural features (faults and a fold). Using groundwater geochemistry data, contour maps of chloride and sulphate concentration largely support the structural sub-division of the area into hydrogeological sub-basins. Scrutiny of groundwater geochemical data, averaged for each sub-basin, confirmed the degree of compartmentalisation and the occurrence of sealed faults. The variation of the geochemical composition of the groundwater not only relates to the different, localised geochemical processes and seawater intrusion but also relate to compartmentalisation due to faulting. Faults have limited the degree of mixing between the groundwater types thus retaining the specific characteristics of each sub-basin. Highly localised seawater intrusion is mainly controlled by low permeability fault close to the Irish Sea and Mersey estuary. There is no effectively no invasion of seawater beyond the faults that lie closest to the coastline. Freshwater recharge to the aquifer must be highly localised and will mainly occur by vertical percolation of rain and surface water rather than whole aquifer-scale groundwater flow.
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Thoret-Bauchet, Q., P. Velex, M. Guingand et P. Casanova. « Simulations of the dynamic response of planetary gears in the presence of localised tooth faults ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 233, no 21-22 (2 mai 2019) : 7212–23. http://dx.doi.org/10.1177/0954406219846153.
Texte intégralRésumé :
This paper is aimed at analysing the influence of local tooth faults such as pitting on the dynamic behaviour of planetary gears. A model of one-stage planetary gear combining lumped parameters and Timoshenko beam elements is presented, which accounts for deformable shafts and ring gears. Local tooth fault are simulated by material removal from tooth flanks, which can be positioned on the sun-gear, the planets and the ring-gear. The corresponding state equations are solved by combining a Newmark time-step integration scheme combined with a unilateral normal contact algorithm, which verifies that all contact forces on gear teeth are compressive and that no contact can occur outside the contact areas. A number of results are presented, which show the influence of tooth fault positions, depths and extents on displacement and acceleration signals. The contribution of a deformable ring-gear is analysed and the possibility to detect such localised tooth faults from vibration monitoring is discussed.
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Mohamed, E. A., et R. H. Worden. « Groundwater compartmentalisation : a water table height and geochemical analysis of the structural controls on the subdivision of a major aquifer, the Sherwood Sandstone, Merseyside, UK ». Hydrology and Earth System Sciences 10, no 1 (8 février 2006) : 49–64. http://dx.doi.org/10.5194/hess-10-49-2006.
Texte intégralRésumé :
Abstract. Compartmentalisation, the subdivision of an aquifer into discrete and relatively isolated units, may be of critical importance for the protection of groundwater although it has been largely ignored in the groundwater literature. The Lower Triassic Sherwood Sandstone, in north west of England, UK, may be a good example of an aquifer that has been compartmentalised by numerous high angle faults with displacements of up to 300 m. The study was initiated to assess the local groundwater flow, the extent of seawater invasion and the controls on recharge in the aquifer and to try to understand whether the aquifer is broken into discrete compartments. Maps and schematic cross-sections of groundwater heads for the years 1993, and 2002 were prepared to trace any structural controls on the groundwater heads across the area. Studying the contour maps and cross sections revealed that: 1) there are substantial differences in groundwater head across some of the NNW-SSE trending faults implying that groundwater flow is strongly limited by faults, 2) an anticline in the east of the area acts as a groundwater divide and 3) the groundwater head seems to follow the topography in some places, although steep changes in groundwater head occur across faults showing that they locally control the groundwater head. The aquifer was thus provisionally subdivided into several hydrogeological sub-basins based on groundwater head patterns and the occurrence of major structural features (faults and a fold). Using groundwater geochemistry data, contour maps of chloride and sulphate concentration largely support the structural sub-division of the area into hydrogeological sub-basins. Scrutiny of groundwater geochemical data, averaged for each sub-basin, confirmed the degree of compartmentalisation and the occurrence of sealed faults. The variation of the geochemical composition of the groundwater not only relates to the different, localised geochemical processes and seawater intrusion but also relates to compartmentalisation due to faulting. Faults have limited the degree of mixing between the groundwater types thus retaining the specific characteristics of each sub-basin. Highly localised seawater intrusion is mainly controlled by low permeability fault close to the Irish Sea and Mersey estuary. There is effectively no invasion of seawater beyond the faults that lie closest to the coastline. Freshwater recharge to the aquifer seems to be highly localised and mainly occurs by vertical percolation of rain and surface water rather than whole aquifer-scale groundwater flow. This study provides a detailed understanding of the groundwater flow processes in Liverpool as an example of methods can be applied to groundwater management elsewhere.
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Török, Ákos, Gyula Bögöly, Árpád Somogyi et Tamás Lovas. « Application of UAV in Topographic Modelling and Structural Geological Mapping of Quarries and Their Surroundings—Delineation of Fault-Bordered Raw Material Reserves ». Sensors 20, no 2 (15 janvier 2020) : 489. http://dx.doi.org/10.3390/s20020489.
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A 3D surface model of an active limestone quarry and a vegetation-covered plateau was created using unmanned aerial vehicle (UAV) technique in combination with terrestrial laser scanning (TLS). The aim of the research was to identify major fault zones that dissect the inaccessible quarry faces and to prepare a model that shows the location of these fault zones at the entire study area. An additional purpose was to calculate reserves of the four identified lithological units. It was only possible to measure faults at the lowermost two meters of the quarry faces. At the upper parts of the quarry and on the vegetation-covered plateau where no field geological information was available, remote sensing was used. Former logs of core drillings were obtained for the modelling of the spatial distribution of four lithological units representing cover beds and various quality of limestone reserves. With the comparison of core data, field measurements and remote sensing, it was possible to depict major faults. Waste material volumes and limestone reserves were calculated for five blocks that are surrounded by these faults. The paper demonstrates that, with remote sensing and with localised control field measurements, it is possible: (a) to provide all geometric data of faults and (b) to create a 3D model with fault planes even at no exposure or at hardly accessible areas. The surface model with detected faults serves as a basis for calculating geological reserves.
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Rudolf, Michael, Matthias Rosenau et Onno Oncken. « Time-dependent frictional properties of granular materials used in analogue modelling : implications for mimicking fault healing during reactivation and inversion ». Solid Earth 14, no 3 (10 mars 2023) : 311–31. http://dx.doi.org/10.5194/se-14-311-2023.
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Abstract. Analogue models are often used to model long-term geological processes such as mountain building or basin inversion. Most of these models use granular materials such as sand or glass beads to simulate the brittle behaviour of the crust. In granular material, deformation is localised in shear bands, which act as an analogue to natural fault zones and detachments. Shear bands, also known as faults, are permanent anomalies in the granular package and are often reactivated during a test run. This is due to their lower strength compared to the undeformed material. When the fault movement stops, time-dependent healing immediately begins to increase the strength of the fault. Faults that have been inactive for a long time therefore have a higher strength than younger faults. This time-dependent healing, also called time consolidation, can therefore affect the structure of an analogue model as the strength of the fault changes over time. Time consolidation is a well-known mechanism in granular mechanics, but it is poorly described for analogue materials and on the timescales of typical analogue models. In this study, we estimate the healing rate of different analogue materials and evaluate the impact on the reactivation potential of analogue faults. We find that healing rates are generally less than 3 % per 10-fold increase in holding time, which is comparable to natural fault zones. We qualitatively compare the frictional properties of the materials with grain characteristics and find a weak correlation of healing rates with sphericity and friction with an average quality score. Accordingly, in models where there are predefined faults or reactivation is forced by blocks, the stability range of the fault angles that can be reactivated can decrease by up to 7∘ over the duration of 12 h. The stress required to reactivate an existing fault can double in the same time, which can favour the development of new faults. In a basin inversion scenario, normal faults cannot be inverted because of the strong misorientation, so time consolidation plays little additional role for such models.
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Chen, Long, Yat Sze Choy, Tian Gang Wang et Yan Kei Chiang. « Fault detection of wheel in wheel/rail system using kurtosis beamforming method ». Structural Health Monitoring 19, no 2 (14 juin 2019) : 495–509. http://dx.doi.org/10.1177/1475921719855444.
Texte intégralRésumé :
Fault detection systems are typically applied in the railway industry to examine the structural health status of the wheel/rail system. We herein propose a time-domain kurtosis beamforming technique using an array of microphones for the fault identification and localisation of the wheel/rail system under an environment with high background noise. As an acoustics-based noncontact diagnosis method, this technique overcomes the challenge of the contact between the sensors and examined structures, and it is more applicable for impulsive signals of broadband nature, such as impact noise generated from faults on the wheel surface. Moreover, the application of kurtosis enables the identification and localisation at low signal-to-noise ratio. Under such circumstance, the impulsive signals generated by faults were totally merged in rolling noise and background noise. Meanwhile, different types of faults on the wheels could be identified and localised by observing the kurtosis value on the beamforming sound map. The effectiveness of the proposed method to diagnose the type of wheel fault with low signal-to-noise ratio and moving source has been validated experimentally. This method may provide a useful tool for the routine maintenance of trains.
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Mason, Jack, Sascha Schneiderwind, Aggelos Pallikarakis, Silke Mechernich, Ioannis Papanikolaou et Klaus Reicherter. « Hanging-wall colluvial cementation along active normal faults ». Quaternary Research 88, no 1 (juillet 2017) : 39–59. http://dx.doi.org/10.1017/qua.2017.32.
Texte intégralRésumé :
AbstractMany active normal faults throughout the Aegean juxtapose footwall limestone against hanging-wall colluvium. In places, this colluvium becomes cemented and forms large hanging-wall lobes or sheets of varying thickness attached to the bedrock fault. Investigations at the Lastros Fault in eastern Crete allow us to define criteria to distinguish between cemented colluvium and fault cataclasite (tectonic breccia), which is often present at bedrock faults. Macro- and microscopic descriptions of the cemented colluvium show that the colluvium was originally deposited through both rockfalls and debris flows. Stable isotope analyses of oxygen and carbon from 83 samples indicate that cementation then occurred through meteoric fluid flow in the fault zone from springs at localised positions along strike. Palaeotemperature calculations of the parent water from which the calcite cement precipitated are indicative of a climate between 7°C and 10°C colder than Crete’s present average annual temperature. This most likely represents the transition between a glacial and interglacial period in the late Pleistocene. Ground-penetrating radar also indicates that cemented colluvium is present in the hanging-wall subsurface below uncemented colluvium. Using these results, a model for the temporal development of the fault and formation of the cemented colluvium is proposed.
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Weatherley, D., et S. Abe. « Earthquake statistics in a Block Slider Model and a fully dynamic Fault Model ». Nonlinear Processes in Geophysics 11, no 5/6 (17 novembre 2004) : 553–60. http://dx.doi.org/10.5194/npg-11-553-2004.
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Abstract. We examine the event statistics obtained from two differing simplified models for earthquake faults. The first model is a reproduction of the Block-Slider model of Carlson et al. (1991), a model often employed in seismicity studies. The second model is an elastodynamic fault model based upon the Lattice Solid Model (LSM) of Mora and Place (1994). We performed simulations in which the fault length was varied in each model and generated synthetic catalogs of event sizes and times. From these catalogs, we constructed interval event size distributions and inter-event time distributions. The larger, localised events in the Block-Slider model displayed the same scaling behaviour as events in the LSM however the distribution of inter-event times was markedly different. The analysis of both event size and inter-event time statistics is an effective method for comparative studies of differing simplified models for earthquake faults.
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McBride, W. James, et Hugh EM Hunt. « Dynamic model of a cylindrical roller on a rough surface, with applications to wind turbine gearbox planetary bearings ». Proceedings of the Institution of Mechanical Engineers, Part J : Journal of Engineering Tribology 233, no 10 (9 janvier 2019) : 1424–32. http://dx.doi.org/10.1177/1350650118822362.
Texte intégralRésumé :
Wind turbines of larger power ratings have become increasingly prevalent in recent years, improving the viability of wind energy as a sustainable energy source. However, these large wind turbines have been subjected to higher rates of failure of the wind turbine gearbox, resulting in larger downtime of operation and an increase in cost due to repairs. These failures most frequently initiate in the gearbox’s bearings, especially in the planetary bearings of the planetary stage and high-speed bearings. Currently, most of the research on the detection of planetary bearing faults only addresses the case of localised faults in the outer bearing race, while fewer research considering the detection of distributed bearing faults. The research that does consider distributed bearing faults relies on techniques – such as machine learning for the identification of faulty bearings – that do not account much for the underlying physics of the bearing. In this paper, a model is developed to simulate and analyse the dynamic interaction of a planetary bearing in the presence of surface roughness, which can be used to represent a distributed fault. The model presented uses random vibration theory for simulating the response of the planet bearing induced by distributed faults. The input of the model considers statistical expressions of the roughness geometry using multiple parallel tracks. Numerical simulation of the random vibration of the model is performed using 16 tracks, and the power spectral density of the radial deflection of the roller and the roller–race contact force is determined. The results of the simulation with the multi-track model show that a single-track model significantly overestimates the power spectral densities, and also suggests the stiffness of the bearing race is too high to have an effect on the roller dynamics for a planet bearing.
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Abboud, D., M. Elbadaoui, S. Becquerelle et M. Lalmi. « The application of the cyclic coherence for distributed planet fault detection in planetary gears ». International Journal of Condition Monitoring 8, no 2 (1 avril 2018) : 58–63. http://dx.doi.org/10.1784/204764218823029075.
Texte intégralRésumé :
The vibration-based condition monitoring of planetary gears is a highly active and challenging field of research. Many signal processing techniques have been proposed, with the aim of promoting the fault component in the signal and, consequently, highlighting the fault signature (ie the damage symptom). Most of these techniques consider the fault contribution as being deterministic, which is true in the case of an advanced and localised fault. Such techniques may fail in other scenarios in which, for instance, the fault is of a distributed nature and its vibrational component is weak. In such a case, the fault component is likely to be randomised and turns cyclostationary. The present paper suggests the presence of an additional cyclostationary component in planetary gear vibrations. The presence of this component is explained by the presence of load fluctuations at the meshing points and the random micro-irregularity in the stiffness of gear components, as well as the presence of distributed faults. A simplified signal model is proposed to explain the vibration signal structure of healthy and faulty planetary gears (with a planet fault in the case of the faulty gear). Also, a cyclostationary-based condition monitoring approach is proposed, based on the cyclic coherence. The proposed approach is validated on real-world vibration signals acquired from a planetary gear benchmark.
Thèses sur le sujet "LOCALISED FAULTS"
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Madau, Maxime. « A methodology to localise EMFI areas on Microcontrollers ». Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS045.
Texte intégralRésumé :
De nos jours, la sécurité des systèmes embarqués prend une place de plus en plus importante. Notamment du fait de l'augmentation de la part du marché prise par l'IoT et le marché automobile.Afin de justifier un certain niveau de sécurité ces systèmes embarqués doivent subir des audits de sécurité afin soit d'obtenir une certification, qui peut s'avérer nécessaire pour adresser certains marché, ou alors plus simplement pour éviter de ternir le nom de l'entreprise en cas de faille.Le chemin d'attaque le plus efficace est probablement l'injection de faute obtenue par une violation volontaire des conditions d'utilisation d'un circuit.De cette faute différent scénarios sont possibles, soit celle-ci est couplée à des outils statistiques pour obtenir la clef secrète d'un algorithme cryptographique, soit elle permet une escalade de privilège.Cette thèse se concentre sur les fautes induites par perturbation électromagnétique, qui est le support qui offre le meilleur compromis précision coût.Si les attaques par injections de fautes se sont montrées maintes fois efficaces dans la littérature, elles possèdent néanmoins un défaut conséquent dans le cadre de l'évaluation sécuritaire. Ce défaut vient du très grand nombre de paramètres offert par l'injection de faute à son utilisateur. Si on ajoute à cela les contraintes temporelles inhérentes à l'évaluation, on se rend compte de la difficulté de garantir la sécurité d'un produit contre de telles menaces.De ce constat il devient évident que des métriques ou stratégie sont nécessaire pour améliorer la qualité des évaluations.Cette thèse est un premier pas dans cette direction et propose de résoudre la complexité spatiales lors d'une campagne évaluation face à l'injection de faute électromagnétique.L'idée est de définir une métrique se basant sur des expérimentations ainsi que l'état de l'art pour réduire l'espace à tester à quelques positions qui vont presque certainement mener à une faute du fait de leur propriété physique.Dans une première partie la création d'un tel critère est présentée. Celui-ci se base sur un modèle simplifié du couplage sonde d'injection circuit et sur le modèle de faute le plus récent.Ensuite les limites d'un tel critère sont analysées afin d'en trouver une amélioration.Cependant, l'injection de faute ne permet pas seulement d'attaquer directement une cible, elle peut aussi diminuer sa sécurité en visant ses contre-mesures.La plupart des contre-mesures ont en commun l'utilisation d'un générateur de nombre aléatoire, c'est pourquoi la robustesse d'un générateur aléatoire récent sera évaluée dans une troisième partie.De cette analyse un chemin d'attaque sera dérivé dans le cadre de l'injection de faute via ondes électromagnétiquesToday, security of embedded devices is put in the limelight with the increasing market share of both IoT and automotive.To ensure a proper level of security to its customer such embedded components must undergo pentesting either to obtain some certifications to address security market but also to avoid tarnishing the name of the firm in case of vulnerability.Amongst the various attack paths, one of most threatening is the voluntary violation of operation condition to induce a fault on a circuit.These faults are then used for privilege escalation or combined with statistic tools to recover cryptographic keys. This thesis focuses on the use of electromagnetic field to generate such faults, this medium being the one that offers the best trade-off between cost and accuracy.The efficiency of such family of attack has already been demonstrated in the literature. Yet fault injection techniques shared a common problem which root cause is the amount of parameter an evaluator has to tweaks to obtain a fault. Therefore, it is hard to state whether a target is protected against fault injection since evaluation is bounded in time, thus exhaustive search is not an option.Metrics or strategies should be defined to get the most out of up to date fault injection methods.This thesis is a first step towards defining such metrics, and proposed to tackle the space complexity of EM fault injection. In other words, according to the attack scenario we developed metrics or strategy relying on both experimentation and state of the art. The aims of those metrics/strategy being to reduce the space on the DUT that undergo electromagnetic emanation to the most likely to be faulted area.In a first part, a criterion based on a basic model of the coupling between the injection probes and the circuit as well as today fault model will be developed.This criterion is then analysed and a refinement is proposed.Yet fault injection could also be used to nullify countermeasure that disable some attack vectors. Most of those countermeasures have in common the use of a true random generator.Thence in a second part we evaluate the robustness of an up to date true random number generator against electromagnetic perturbation.From this analysis we derived which parts of true random number generator are more relevant to be targeted using electromagnetic waves
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Masmoudi, Mohamed Lamine. « Détection d'un défaut localisé dans un multiplicateur d'éolienne : approche par analyse des grandeurs électromécaniques ». Thesis, La Rochelle, 2015. http://www.theses.fr/2015LAROS001.
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Le travail présenté dans ce mémoire a été effectué dans le cadre du projet FEDER ”Maintenance prédictive des éoliennes et maîtrise des impacts environnementaux”. Un des objectifs du projet a été de développer, dans le Poitou-Charentes, des compétences dans le domaine de l’éolien en lien avec les activités des laboratoires LIAS et LaSIE. Pour le LIAS, il a été décidé de lancer une nouvelle activité de recherche sur le diagnostic de défauts mécaniques. Le cadre du projet concernant l’éolien, les défauts localisés dans les multiplicateurs ont été privilégiés. Par ailleurs, nous avons restreint l’étude au régime stationnaire afin de simplifier l’apprentissage des différents phénomènes mis en jeu et des techniques de traitement du signal utilisées. Dans une première partie, nous avons étudié les signatures de défaut sur les signaux vibratoires. Cette phase a été facilitée par l’utilisation des données expérimentales mise à disposition par le Bearing Data Center de la Case Western Reserve - University de Cleveland. Parmi les méthodes de traitement de signal utilisées, nous avons opté pour l’analyse d’enveloppe mise en oeuvre dans les techniques de type Time Synchronous Analysis (TSA). A cette occasion, nous avons défini une procédure complète de détection de défaut que nous avons conservée tout au long de cette étude en appliquant une technique d’identification de type PNL qui nous a permis d’obtenir des résultats comparables à des méthodes haute résolution de type ESPRIT. Par la suite, nous nous sommes recentrés sur l’application éolienne en réalisant un banc d’essai original permettant d’émuler un défaut au niveau de l’accouplement de deux machines électriques. L’idée principale a été de recenser l’ensemble des signaux exploitables dans le cadre de la détection du défaut émulé et de fournir une classification entre les courants électriques, le couple mécanique et la vitesse des machines. Par ailleurs, un comparatif entre signaux mesurés et signaux estimés a été présenté. Il en ressort qu’il est possible d’obtenir un signal observé plus riche que la mesure directe en terme de composantes spectrales liées au défaut. Cette amélioration est rendue possible par une synthèse adéquate des gains d’observation qui a été obtenue après linéarisation de l’observateur étudié. En marge de l’application éolienne, le cas d’un moteur commandé vectoriellement a été abordé. L’idée a été d’exploiter les performances de la boucle de vitesse afin d’amplifier les composantes recherchées dans les courants électriques. L’ensemble de ces pistes de recherches a été testé en simulation et expérimentalementThe work presented in this thesis was carried out under the FEDER project ”Maintenance prédictive des éoliennes et maîtrise des impacts environnementaux”. One of the project objectives was to develop, in Poitou-Charentes, expertise in the field of wind power in connection with the activities of LIAS and LaSIE laboratories. For LIAS, it was decided to launch a new research activity on the diagnosis of mechanical faults. The localized defects in gearbox were privileged. Furthermore, we restricted the study to the stationary system to simplify the learning of different phenomena involved and signal processing techniques. In the first part, we studied the fault signatures on the vibration signals. This phase was facilitated by the use of experimental data available from the Bearing Data Center of the Case Western Reserve - Cleveland University. Among the signal processing methods, we opted for envelope analysis implemented in the Synchronous Time Averaging (TSA). On this occasion, we defined a comprehensive fault detection procedure that we have maintained throughout this study by applying a NLP identification technique where we obtained similar results compared to high-resolution methods as ESPRIT. There after, we refocused on wind power applications by making an original test bench capable of emulating a fault in the coupling of two electrical machines. The main idea was to identify all usable signals in the context of emulated fault detection and to provide a classification between electric currents, mechanical torque and speed of the machines. Moreover, a comparison between measured signals and estimated ones was discussed. It shows that it is possible to get an observed signal richer than direct signal measurement in terms of spectral components related to the defect. This improvement is made possible by an appropriate synthesis of gains observer which was obtained after linearization of the studied observer. In the margin of wind application, the case of a motor controlled by vector was also discussed. The idea was to exploit the speed loop performance to amplify the fault components in electrical currents. All these researches have been tested in simulation and experimentally
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Vu, Chinh Trung. « An Energy-Efficient Distributed Algorithm for k-Coverage Problem in Wireless Sensor Networks ». Digital Archive @ GSU, 2007. http://digitalarchive.gsu.edu/cs_theses/40.
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Wireless sensor networks (WSNs) have recently achieved a great deal of attention due to its numerous attractive applications in many different fields. Sensors and WSNs possesses a number of special characteristics that make them very promising in many applications, but also put on them lots of constraints that make issues in sensor network particularly difficult. These issues may include topology control, routing, coverage, security, and data management. In this thesis, we focus our attention on the coverage problem. Firstly, we define the Sensor Energy-efficient Scheduling for k-coverage (SESK) problem. We then solve it by proposing a novel, completely localized and distributed scheduling approach, naming Distributed Energy-efficient Scheduling for k-coverage (DESK) such that the energy consumption among all the sensors is balanced, and the network lifetime is maximized while still satisfying the k-coverage requirement. Finally, in related work section we conduct an extensive survey of the existing work in literature that focuses on with the coverage problem.
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Obeid, Ziad. « Mise au point d'algorithmes pour la détection de dégradations de roulements d'actionneurs synchrones à aimants permanents. Application dans le domaine aéronautique sur des ventilateurs embarqués ». Phd thesis, Toulouse, INPT, 2012. http://oatao.univ-toulouse.fr/14176/1/obeid_partie_1_sur_2.pdf.
Texte intégralRésumé :
Ce travail de thèse traite de la détection des défauts mécaniques des roulements à billes par analyse de grandeurs mécaniques et électriques dans des machines synchrones à aimants permanents haute vitesse. Le domaine applicatif de ce travail concerne l'aéronautique. Généralement, pour surveiller l'état des roulements à billes dans un actionneur électrique, des mesures vibratoires sont réalisées. Elles permettent, en exploitant le spectre du signal vibratoire, de mettre facilement en évidence la détérioration du roulement. Cette méthode de surveillance est cependant relativement couteuse en termes d'instrumentation et le placement d'un capteur vibratoire dans des équipements à fort degré d'intégration est parfois difficile. Nous proposons dans ce mémoire d'utiliser d'autres grandeurs physiques prélevées sur le système pour réaliser la surveillance de ces défauts. Il peut s'agir de grandeurs mécaniques (vitesse, position par exemple) et de grandeurs électriques (courant statorique, courant onduleur par exemple). L'utilisation de données déjà disponibles dans l'équipement pour les besoins de la commande permet ainsi de supprimer le système d'acquisition vibratoire. A partir d'enregistrements temporels de données réalisées au cours de campagnes d'essais, nous proposons des méthodologies de traitement du signal permettant d'extraire automatiquement des informations sensibles au défaut à surveiller. L'idée finale est de construire des indicateurs de l'état de santé des roulements permettant de prendre « juste à temps » des décisions fiables relatives à la maintenance ou à la sécurisation de l'équipement. Pour construire ces indicateurs, les signatures spécifiques aux défauts de roulements sont étudiées de manière théorique et expérimentale, pour l'ensemble des grandeurs prélevées. Leurs propriétés sont mises en évidence, permettant ainsi de définir les bandes fréquentielles les plus contributives au diagnostic. L'extraction de ces signatures est réalisée dans le domaine fréquentiel selon plusieurs méthodes. Deux types d'indicateurs automatiques différents sont proposés. Le premier est construit directement à partir du spectre d'amplitude des grandeurs par extraction de l'amplitude des harmoniques dans des bandes fréquentielles particulières. Le second intègre une dimension statistique dans l'analyse en exploitant le caractère aléatoire de certains harmoniques pour détecter la présence du défaut. Des critères de comparaison sont définis et utilisés pour étudier les performances des indicateurs proposés pour deux campagnes d'essais avec des roulements artificiellement dégradés, pour différentes vitesses de fonctionnement et pour différents paramètres de réglage des indicateurs.
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Vu, Chinh Trung. « Distributed Energy-Efficient Solutions for Area Coverage Problems in Wireless Sensor Networks ». Digital Archive @ GSU, 2009. http://digitalarchive.gsu.edu/cs_diss/37.
Texte intégralRésumé :
Wireless sensor networks (WSNs) have recently attracted a great deal of attention due to their numerous attractive applications in many different fields. Sensors and WSNs possess a number of special characteristics that make them very promising in a wide range of applications, but they also put on them lots of constraints that make issues in sensor network particularly challenging. These issues may include topology control, routing, coverage, security, data management and many others. Among them, coverage problem is one of the most fundamental ones for which a WSN has to watch over the environment such as a forest (area coverage) or set of subjects such as collection of precious renaissance paintings (target of point coverage) in order for the network to be able to collect environment parameters, and maybe further monitor the environment. In this dissertation, we highly focus on the area coverage problem. With no assumption of sensors’ locations (i.e., the sensor network is randomly deployed), we only consider distributed and parallel scheduling methods with the ultimate objective of maximizing network lifetime. Additionally, the proposed solutions (including algorithms, a scheme, and a framework) have to be energy-efficient. Generally, we investigate numerous generalizations and variants of the basic coverage problem. Those problems of interest include k-coverage, composite event detection, partial coverage, and coverage for adjustable sensing range network. Various proposed algorithms. In addition, a scheme and a framework are also suggested to solve those problems. The scheme, which is designed for emergency alarming applications, specifies the guidelines for data and communication patterns that significantly reduce the energy consumption and guarantee very low notification delay. For partial coverage problem, we propose a universal framework (consisting of four strategies) which can take almost any complete-coverage algorithm as an input to generate an algorithm for partial coverage. Among the four strategies, two pairs of strategies are trade-off in terms of network lifetime and coverage uniformity. Extensive simulations are conducted to validate the efficiency of each of our proposed solutions.
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SINGH, YAMAL. « FINITE ELEMENT ANALYSIS OF LOCALISED FAULT IN DEEP GROOVE BALL BEARING ». Thesis, 2017. http://dspace.dtu.ac.in:8080/jspui/handle/repository/15958.
Texte intégralRésumé :
Rolling element bearings as an important component in almost all types of rotating machines have been wide spreadly used and its failure is one of the foremost causes of failure and breakdowns in rotating machinery, resulting in significant economic loss. It is highly imperative to investigate the failure causes in order to improve the design and operating conditions to bear with the decreasing overall efficiency and economics involved.
In present age many industries benefit from the use of deep groove ball bearings like, Agricultural, food processing, machine tool, material handling, medical / pharmaceutical and wind energy etc. Deep groove ball bearings are versatile as they can carry radial and axial loads, they have a wider range of applications for many industries and they lead to cost savings because they create less friction torque, this lowers operating temperature (which extends the life of the bearing) and reduces energy cost of running equipment (such as conveyor belts). Require less upkeep because of their simple design, low operating temperature, and low friction, deep groove ball bearings have a longer expected shelf life than other bearings. They do not require additional lubrication after installation, which also means less maintenance downtime. But due to mishandling, environmental effects and failure in operational conditions there is development of localized and distributed defects over the time, which lead to lead to seizing of machinery gradually that leads to down time. From practical conditional monitoring to FEA and dynamic models have been developed for these defects in ball bearing and thus to minimize the detrimental effects associated.
Finite element analysis is used to model the localised faults in inner race of deep groove ball bearing. Ansys workbench’s transient module is used to simulate the impact over the defect and nodal parameters are captured to understand the severity of vibrations generated by the defects upon interaction with the balls in one contact simulation. The feasibility of FEA is also established for the modelling of faults in ball bearing and simplistic approach for most convenient way of simulating such
defects have been developed for further studies in this field. The project focuses on procedural detailing and using apt solvers to arrive to most time efficient simulation technique. Dynamics of the system is very well projected by the transient model of faulted ball bearing.
Emphasis is laid on analysing the impact of varying sizes of the faults on the severity of vibrations created upon interaction of ball over the defect on the inner race for single pass. Comparative study between cylindrical and square faults of same longitudinal and lateral sizes have been done to implicate their detrimental effects on the operation of the faulted deep grove ball bearing. Simulation results show that as defect size increases the severity of vibration increase drastically and rectangular defects prove to produce much adverse effects as compared to cylindrical defects. Further research avenues for modelling and simulation of faults in bearing have been suggested.
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Becker, Andrew 1987. « Off-fault Damage Associated with a Localized Bend in the North Branch San Gabriel Fault, California ». Thesis, 2012. http://hdl.handle.net/1969.1/148091.
Texte intégralRésumé :
Structures within very large displacement, mature fault zones, such as the North Branch San Gabriel Fault (NBSGF), are the product of a complex combination of processes. Off-fault damage within a damage zone and first-order geometric asperities, such as bends and steps, are thought to affect earthquake rupture propagation and energy radiation, but the effects are not completely understood. We hypothesize that the rate of accumulation of new damage decreases as fault maturity increases, and damage magnitude saturates in very large displacement faults. Nonetheless, geometric irregularities in the fault surface may modify damage zone characteristics. Accordingly, we seek to investigate the orientation, kinematics, and density of features at a range of scales within the damage zone adjacent to an abrupt 13 degree bend over 425 m in the NBSGF in order to constrain the relative role of the initiation of new damage versus the reactivation of preexisting damage adjacent to a bend.
Field investigation and microstructural study focused on structural domains before, within, and after the fault bend on both sides of the fault. Subsidiary fault fabrics are similar in all domains outside the bend, which suggests a steady state fracture density and orientation distribution is established on the straight segments before and after the bend. The density of fractures within and outside the bend is similar; however, subsidiary fault orientations and kinematics are different within the bend relative to the straight segments. These observations are best explained by relatively low rates of damage generation relative to rates of fault reactivation during the later stages of faulting on the NBSGF, and that damage zone kinematics is reset as the host rock moves into the bend and again upon exiting the bend. Consequently, significant energy released during earthquake unloading can be dissipated by reactivation and slip on existing fractures in the damage zone, particularly adjacent to mesoscale faults. Thus, areas of heightened reactivation of damage, such as adjacent to geometric irregularities in the fault surface, could affect earthquake rupture dynamics.
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Li, Ci-Rong, et 李奇融. « Localized Fault-Tolerant Event Boundary Detection Algorithms in Wireless Sensor Networks ». Thesis, 2007. http://ndltd.ncl.edu.tw/handle/31466157402032571156.
Texte intégralRésumé :
碩士中華大學
資訊工程學系(所)
95
A wireless sensor network is composed of a large number of tiny sensor nodes which can monitor environment, communicate wirelessly, do computations and report the occurrences of interesting events (e.g. forest fire, chemical spills, etc.). Event boundary detection is in and of itself a useful application in wireless sensor networks. Typically, it includes the detection of a large-scale spatial phenomenon such as the transportation front line of a contamination or the diagnosis of network health. In this thesis, we consider the problem of event boundary detection in wireless sensor networks (WSNs). We consider two different models for the problem and propose two algorithms for fault-tolerant event boundary detection, respectively. Our schemes are purely localized and thus are suitable for large scale of WSNs. The computational overhead is low since the schemes are based on a simple clustering technique which only simple numerical operations and binary operations are involved. Simulation results show that our proposed algorithms can clearly detect the event boundary with higher precision than previous algorithms.
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劉原瑞. « Nonlinear Process Monitoring and Fault Isolation using Manifold Learning and Localized Information ». Thesis, 2013. http://ndltd.ncl.edu.tw/handle/00879467286796685475.
Texte intégralLivres sur le sujet "LOCALISED FAULTS"
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Hardin, Garrett. Living within Limits. Oxford University Press, 1993. http://dx.doi.org/10.1093/oso/9780195078114.001.0001.
Texte intégralRésumé :
We fail to mandate economic sanity, writes Garrett Hardin, "because our brains are addled by...compassion." With such startling assertions, Hardin has cut a swathe through the field of ecology for decades, winning a reputation as a fearless and original thinker. A prominent biologist, ecological philosopher, and keen student of human population control, Hardin now offers the finest summation of his work to date, with an eloquent argument for accepting the limits of the earth's resources--and the hard choices we must make to live within them. In Living Within Limits, Hardin focuses on the neglected problem of overpopulation, making a forceful case for dramatically changing the way we live in and manage our world. Our world itself, he writes, is in the dilemma of the lifeboat: it can only hold a certain number of people before it sinks--not everyone can be saved. The old idea of progress and limitless growth misses the point that the earth (and each part of it) has a limited carrying capacity; sentimentality should not cloud our ability to take necessary steps to limit population. But Hardin refutes the notion that goodwill and voluntary restraints will be enough. Instead, nations where population is growing must suffer the consequences alone. Too often, he writes, we operate on the faulty principle of shared costs matched with private profits. In Hardin's famous essay, "The Tragedy of the Commons," he showed how a village common pasture suffers from overgrazing because each villager puts as many cattle on it as possible--since the costs of grazing are shared by everyone, but the profits go to the individual. The metaphor applies to global ecology, he argues, making a powerful case for closed borders and an end to immigration from poor nations to rich ones. "The production of human beings is the result of very localized human actions; corrective action must be local....Globalizing the 'population problem' would only ensure that it would never be solved." Hardin does not shrink from the startling implications of his argument, as he criticizes the shipment of food to overpopulated regions and asserts that coercion in population control is inevitable. But he also proposes a free flow of information across boundaries, to allow each state to help itself. "The time-honored practice of pollute and move on is no longer acceptable," Hardin tells us. We now fill the globe, and we have no where else to go. In this powerful book, one of our leading ecological philosophers points out the hard choices we must make--and the solutions we have been afraid to consider.
Chapitres de livres sur le sujet "LOCALISED FAULTS"
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Ruzhich, Valery V., et Evgeny V. Shilko. « A New Method for Seismically Safe Managing of Seismotectonic Deformations in Fault Zones ». Dans Springer Tracts in Mechanical Engineering, 45–66. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-60124-9_3.
Texte intégralRésumé :
AbstractThe authors outline the results of long-term interdisciplinary research aimed at identifying the possibility and the methods of controlling tangential displacements in seismically dangerous faults to reduce the seismic risk of potential earthquakes. The studies include full-scale physical and numerical modeling of P-T conditions in the earth’s crust contributing to the initiation of displacement in the stick-slip regime and associated seismic radiation. A cooperation of specialists in physical mesomechanics, seismogeology, geomechanics, and tribology made it possible to combine and generalize data on the mechanisms for the formation of the sources of dangerous earthquakes in the highly stressed segments of faults. We consider the prospect of man-caused actions on the deep horizons of fault zones using powerful shocks or vibrations in combination with injecting aqueous solutions through deep wells to manage the slip mode. We show that such actions contribute to a decrease in the coseismic slip velocity in the fault zone, and, therefore, cause a decrease in the amplitude and energy of seismic vibrations. In conclusion, we substantiate the efficiency of the use of combined impacts on potentially seismically hazardous segments of fault zones identified in the medium-term seismic prognosis. Finally, we discuss the importance of the full-scale validation of the proposed approach to managing the displacement regime in highly-stressed segments of fault zones. Validation should be based on large-scale tests involving advanced technologies for drilling deep multidirectional wells, injection of complex fluids, and localized vibrational or pulse impacts on deep horizons.
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Galybin, A. N. « Localised fault instability triggered by water injection ». Dans Bifurcation and Localisation Theory in Geomechanics, 303–10. London : CRC Press, 2021. http://dx.doi.org/10.1201/9781003210931-42.
Texte intégral
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Shi, Lei, Yuepeng Wang, Rajeev Alur et Boon Thau Loo. « Automatic Repair for Network Programs ». Dans Tools and Algorithms for the Construction and Analysis of Systems, 353–72. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-99527-0_19.
Texte intégralRésumé :
AbstractDebugging imperative network programs is a difficult task for operators as it requires understanding various network modules and complicated data structures. For this purpose, this paper presents an automated technique for repairing network programs with respect to unit tests. Given as input a faulty network program and a set of unit tests, our approach localizes the fault through symbolic reasoning, and synthesizes a patch ensuring that the repaired program passes all unit tests. It applies domain-specific abstraction to simplify network data structures and exploits function summary reuse for modular symbolic analysis. We have implemented the proposed techniques in a tool called NetRep and evaluated it on 10 benchmarks adapted from real-world software-defined network controllers. The evaluation results demonstrate the effectiveness and efficiency of NetRep for repairing network programs.
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Rzeszuciński, Paweł, et James R. Ottewill. « Parallel Autoregressive Modeling as a Tool for Diagnosing Localized Gear Tooth Faults ». Dans Lecture Notes in Mechanical Engineering, 207–15. Berlin, Heidelberg : Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-39348-8_17.
Texte intégral
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Soomro, Safeeullah, et Franz Wotawa. « Detect and Localize Faults in Alias-Free Programs Using Specification Knowledge ». Dans Next-Generation Applied Intelligence, 379–88. Berlin, Heidelberg : Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-02568-6_39.
Texte intégral
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Guillen, Oscar M., Michael Gruber et Fabrizio De Santis. « Low-Cost Setup for Localized Semi-invasive Optical Fault Injection Attacks ». Dans Constructive Side-Channel Analysis and Secure Design, 207–22. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-64647-3_13.
Texte intégral
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Rzeszucinski, Pawel, Michal Juraszek et James R. Ottewill. « A Frequency-Based Criterion for Automatic Selection of the Optimal Intrinsic Mode Function in Diagnostics of Localized Gear Tooth Faults ». Dans Mechanisms and Machine Science, 485–93. Cham : Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-09918-7_43.
Texte intégral
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Singleton*, John S., Nikki M. Seymour et Evan D. Strickland. « The Buckskin-Rawhide and northern Plomosa Mountains metamorphic core complexes, west-central Arizona, USA ». Dans Field Excursions from Las Vegas, Nevada : Guides to the 2022 GSA Cordilleran and Rocky Mountain Joint Section Meeting, 85–107. Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.0063(05).
Texte intégralRésumé :
ABSTRACT The Buckskin-Rawhide and northern Plomosa Mountains in west-central Arizona are metamorphic core complexes that record NE-directed, large-magnitude extension in the early to middle Miocene. Both core complexes consist of mylonites exposed in the footwall of corrugated, low-angle detachment faults. The Late Cretaceous Orocopia Schist and early Miocene intrusions dominate the mylonitic footwall of the northern Plomosa Mountains. The Orocopia Schist was emplaced during low-angle subduction of the Farallon plate and exhibits the hallmarks of the underplated Laramide subduction complexes, including blocks of metasomatized peridotite encased in quartzofeldspathic schist. In the Buckskin-Rawhide Mountains, carbonate-rich metasedimentary rocks that were buried to midcrustal depths by Mesozoic thrust faults preferentially absorbed Miocene footwall strain and localized the Buckskin detachment fault. A correlation between distinct granodiorite in the footwall of the Buckskin detachment fault in the eastern Bouse Hills and a hanging-wall conglomerate sourced from this granodiorite provides constraints on middle Miocene displacement across the detachment fault and indicates that displacement increased northeastward in the slip direction. The termination of slip on the Buckskin detachment fault also younged northeastward, largely ending by ca. 19 Ma in the western Bouse Hills and ca. 17 Ma in the westernmost Buckskin Mountains, but continuing to <16 Ma in the southern Buckskin Mountains and to ca. 12 Ma in the eastern Buckskin Mountains. Late stages of slip on the detachment fault record minor NW-SE shortening during amplification of corrugation folds. Postdetachment faulting across the region was dominated by dextral and oblique-dextral slip on NW-striking faults influenced by the Pacific–North America plate boundary. Locations visited on this three-day field trip highlight the structural evolution of these metamorphic core complexes.
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Tripp, Gerard I., Richard M. Tosdal, Thomas Blenkinsop, Jamie R. Rogers et Scott Halley. « Chapter 33 : Neoarchean Eastern Goldfields of Western Australia ». Dans Geology of the World’s Major Gold Deposits and Provinces, 709–34. Society of Economic Geologists, 2020. http://dx.doi.org/10.5382/sp.23.33.
Texte intégralRésumé :
Abstract Neoarchean greenstone-hosted gold deposits in the Eastern Goldfields Superterrane of the Yilgarn craton of Western Australia are diverse in style, timing with respect to magmatic activity, structural environment, host rocks, and geochemical character. Geologic constraints for the range of gold deposits indicate deposit formation synchronous with volcanism, synchronous with syn- and postvolcanic intrusion, synchronous with postvolcanic deformation in faults and shear zones, or some combination of superposed events over time. The gold deposits are distributed as clusters along linear belt-parallel fault zones internal to greenstone belts but show no association with major terrane boundary faults. World-class gold districts are associated with the thickest, internal parts of the greenstone belts identified by stratigraphic preservation and low metamorphic grades. Ore-proximal faults in those regions are more commonly associated with syn- and postvolcanic structures related to greenstone construction and deformation rather than major terrane amalgamation. Using the Kalgoorlie district as a template, the gold deposits show a predictable regional association with thicker greenstone rocks overlain unconformably by coarse clastic rock sequences in the uppermost units of the greenstone stratigraphy. At a camp scale, major gold deposits show a spatial association with unconformable epiclastic and volcaniclastic rocks located above an unconformity internal to the Black Flag Group. Distinct episodes of gold deposition in coincident locations suggest fundamental crustal structural controls provided by the fault architecture. Late penetrative deformation and metamorphism overprinted the greenstone rocks and the older components of many gold deposits and were accompanied by major gold deposition in late quartz-carbonate veins localized in crustal shear zones or their higher order fault splays.
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Wakabayashi, John. « Subduction and exhumation slip accommodation at depths of 10–80 km inferred from field geology of exhumed rocks : Evidence for temporal-spatial localization of slip ». Dans Plate Tectonics, Ophiolites, and Societal Significance of Geology : A Celebration of the Career of Eldridge Moores. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.2552(12).
Texte intégralRésumé :
ABSTRACT Field relationships in the Franciscan Complex of California suggest localization of subduction slip in narrow zones (≤300 m thick) at the depths of ∼10–80 km. Accretionary and non-accretionary subduction slip over the ca. 150 Ma of Franciscan history was accommodated across the structural thickness of the complex (maximum of ∼30 km). During accretion of a specific unit (<5 Ma), subduction slip (accretionary subduction slip) deformed the full thickness of the accreting unit (≤5 km), primarily on discrete faults of <20 m in thickness, with the remainder accommodated by penetrative deformation. Some faults accommodating accretionary subduction slip formed anastomosing zones ≤200 m thick that resulted in block-in-matrix (tectonic mélange) relationships but did not emplace exotic blocks. Mélange horizons with exotic blocks range in thickness from 0.5 m to 1 km. These apparently formed by sedimentary processes as part of the trench fill prior to subsequent deformation during subduction-accretion. Accretionary subduction slip was localized within some of these mélanges in zones ≤300 m thick. Such deformation obscured primary sedimentary textures. Non-accretionary subduction faults separate units accreted at different times, but these <100-m-thick fault zones capture a small fraction of associated subduction slip because of footwall subduction and likely removal of hanging wall by subduction erosion. Most exhumation was accommodated by discrete faults ≤30 m thick. Structural, geochronologic, and plate motion data suggest that of the ∼13,000 km of subduction during the ca. 150 Ma assembly of the Franciscan Complex, ∼2000 km was associated with accretion.
Actes de conférences sur le sujet "LOCALISED FAULTS"
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Rajabi, M., A. Salmachi et P. Tavoosiiraj. « Effects of Localised Stress Perturbations on Natural Fractures and Permeability : An example from the Gunnedah Basin ». Dans 2nd EAGE Workshop on Fluid Flow in Faults and Fracture - Modelling, Uncertainty and Risk. European Association of Geoscientists & Engineers, 2023. http://dx.doi.org/10.3997/2214-4609.202373017.
Texte intégral
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Moghadam, Armin, et Fatemeh Davoudi Kakhki. « Empirical Study of Machine Learning for Intelligent Bearing Fault Diagnosis ». Dans 14th International Conference on Applied Human Factors and Ergonomics (AHFE 2023). AHFE International, 2023. http://dx.doi.org/10.54941/ahfe1003049.
Texte intégralRésumé :
Bearing failure highly impacts performance and production of manufacturing systems, causes safety incidents, and results in casualties and property loss. According to the current literature, bearing faults cause 30-40% of all failures in induction motors. Therefore, identification of bearing faults, at early stages, is crucial to ensure seamless and reliable operation of induction motors in industrial and manufacturing operations. Faults occur in four components of bearing: inner race, outer race, ball, and cage. Regardless of the component in which fault occurs, it causes changes in vibration signals. Therefore, comparing normal signals with faulty ones is helpful in detecting localized faults in bearings. We use a benchmark publicly-available data set to conduct this analysis. The main challenge in using publicly-available benchmark datasets for fault detection is lack of manual for instruction on analysis experiments on the original data, which leaves researchers with the challenge and opportunity of applying various analytical methods for achieving higher accuracy rates and useful models for fault detection. This study presents a machine learning-based fault detection and classification scheme in induction motors to evaluate the significance and effects of various data preparation and feature extraction methods on accuracy and reliability of fault detection outcomes. The data preparation stage includes discussion of efficient data dimension reduction, and noise eradication, as well as feature extraction methods for induction motor signals. The main methodology is developing a variety of machine learning classifiers for detection and classification of normal bearings versus faulty bearings. Finally, the implications of the methodology and results for early fault diagnosis and enhanced reliability, as well as maintenance planning efforts in manufacturing systems are discussed. This study introduces proper implementation of machine learning models to improve system performance with higher speed and reliability. Furthermore, the methodology and results contribute to planning and undertaking maintenance operation more efficiently. Therefore, the approach, methodology, and results will be beneficial to both researchers and practitioners involved in manufacturing systems reliability analysis and optimization.
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Markou, N., et P. Papanastasiou. « 3D Geomechanical Reservoir Modelling in Faulted Reservoirs ». Dans International Geomechanics Symposium. ARMA, 2022. http://dx.doi.org/10.56952/igs-2022-167.
Texte intégralRésumé :
Abstract In this study, we present a three-dimensional (3D) geomechanical reservoir model for a faulted and compartmentalized reservoir in the Eastern Mediterranean. A series of alternative production scenarios performed using a simulation model that accounts for consolidation and plasticity deformation of the rocks. Plastic yielding is mainly developed in fault slip zones of narrow extent whereas it appears that there is low risk of plastic behavior in the main reservoir. The slip conditions become complex in the fault contact surfaces where local areas close to fault connections are more pronounced to slip creating localized areas of smaller faulted zones. Displacement magnitudes, are controlled by the structural boundary conditions and the geometrical shape of each fault block. Overall, the higher displacements develop in the near fault region while in the remote from the fault area the vertical displacement is nearly constant as it is clearly governed by the reservoir depletion. Furthermore, changes of normalized permeability can be drawn in the 3D space providing additional insights of heterogeneous distribution. Introduction Petroleum geomechanics become important in reservoirs highly impacted by faults mechanics and overpressure zones. An operator has to well define the fault structural geometry of the field and assess early in the producing life of a reservoir whether production will be affected by the presence of naturally occurring fractures though some faults and fractures cannot be identified even at the early stages of a field production. Reservoir depletion increases the stress carried by the load-bearing grain frame of the reservoir rock. Stress analysis can be extended to identify rock failure conditions that can lead to the creation of new faulted systems in the subsurface formations. Geomechanics play an important role in identifying the stress conditions in a faulted reservoir system and the potential of slip activation of an existing fault. Extensive accounts on the importance of reservoir geomechanics can be found in the classical books of Fjaer et al., (2008) and Zoback, (2010). Finite element analysis can be used to simulate the tectonic movement to match borehole observations (Plumb et al., 1998).
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D’Elia, Gianluca, Simone Delvecchio, Marco Cocconcelli et Giorgio Dalpiaz. « Application of Cyclostationary Indicators for the Diagnostics of Distributed Faults in Ball Bearings ». Dans ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12804.
Texte intégralRésumé :
This paper deals with the detection of distributed faults in ball bearings. In literature most of the authors focus their attention on the detection of incipient localized defects. In that case classical techniques (i.e. statistical parameters, envelope analysis) are robust in recognizing the presence of the fault and its characteristic frequency. In this paper the authors focalize their attention on bearings affected by distributed faults, due to the progressive growing of surface wear or to low-quality manufacturing process. These faults can not be detected by classical techniques; in fact, in this case the signal does not contain impulses at the fault characteristic frequency, but more complex components with strong non-stationary contents. Distributed faults are here detected by means of advanced tools directly derived from the theory of cyclostationarity. In particular three metrics — namely Integrated Cyclic Coherence (ICC), Integrated Cyclic Modulation Coherence (ICMC) and Indicator of Second-Order Cyclostationarity (ICS2x) — have been calculated in order to condense the information given by the cyclostationary analysis and to help the analyst in detecting the fault in a fast fault diagnosis procedure. These indicators are applied on actual signals captured on a test rig where a degreased bearing running under radial load developed accelerated wear. The results indicated that all the three cyclostationary indicators are able to detect both the appearance of a localized fault and its development in a distributed fault, whilst the usual approach fails as the fault grows.
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Kiyan, T., C. Boit et C. Brillert. « Timing Sensitivity Analysis of Logical Nodes in Scan Design Integrated Circuits by Pulsed Diode Laser Stimulation ». Dans ISTFA 2008. ASM International, 2008. http://dx.doi.org/10.31399/asm.cp.istfa2008p0180.
Texte intégralRésumé :
Abstract In this paper, a methodology based upon laser stimulation and a comparison of continuous wave and pulsed laser operation will be presented that localizes the fault relevant sites in a fully functional scan chain cell. The technique uses a laser incident from the backside to inject soft faults into internal nodes of a master-slave scan flip-flop in consequence of localized photocurrent. Depending on the illuminated type of the transistors (n- or p-type), injection of a logic ‘0’ or ‘1’ into the master or the slave stage of a flip-flop takes place. The laser pulse is externally triggered and can easily be shifted to various time slots in reference to clock and scan pattern. This feature of the laser diode allows triggering the laser pulse on the rising or the falling edge of the clock. Therefore, it is possible to choose the stage of the flip-flop in which the fault injection should occur. It is also demonstrated that the technique is able to identify the most sensitive signal condition for fault injection with a better time resolution than the pulse width of the laser, a significant improvement for failure analysis of integrated circuits.
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Sanada, M. « A CAD-Based Approach to Failure Diagnosis of CMOSLSI with Single Fault Using Abnormal IDDQ ». Dans ISTFA 1997. ASM International, 1997. http://dx.doi.org/10.31399/asm.cp.istfa1997p0015.
Texte intégralRésumé :
Abstract A CAD-based fault diagnosis technique for CMOS-LSI with single fault using abnormal IDDQ has been developed to indicate the presence of physical damage in a circuit. This method of progressively reducingthe faulty portion, works by extracting the inner logic state of each block from logic simulation, and by deriving test vector numbers with abnormal IDDQ. To easily perform fault diagnosis, the hierarchical circuit structure is divided into primitive blocks including simple logic gates. The diagnosis technique employs the comparative operation of each primitive block to determine whether one and the same inner logic state with abnormal IDDQ exists in the inner logic state with normal IDDQ or not. The former block is regarded as normal block and the latter block is regarded as faulty block. The fault of the faulty block can be localized easily by using input logic state simulation. Experimental results on real faulty LSI with 100k gates demonstrated rapid diagnosis times of within ten hours ani reliable extraction of the fault location.
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Bakhtiary-Nejad, F., A. H. Nayeb et S. E. Yeganeh. « Application of Vibration Analysis in Ball Bearing Fault Detection ». Dans ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/detc2005-84544.
Texte intégralRésumé :
In this paper, existence of localized defects in a ball bearing has been diagnosed using vibration analysis. First, different kinds of faults which occur in ball bearings have been investigated. Then an analytical model has been proposed for determining the damaged ball bearing vibrations due to a localized defect. Also various methods of fault detection have been evaluated. Next, in order to examine the ball bearings, a testing set-up has been designed and constructed. Then by preparing a computer program, which calculates defect frequencies, some ball bearings have been tested. The test results were originally derived in time-domain. Then by using vibration analysis of healthy and damaged ball bearings in frequency-domain, a fault detection method for ball bearings has been proposed.
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Jain, Sharad, et Hugh Hunt. « Vibration Response of a Wind-Turbine Planetary Gear Set in the Presence of a Localized Planet Bearing Defect ». Dans ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-63452.
Texte intégralRésumé :
In a wind-turbine gearbox, planet bearings exhibit a high failure rate and are considered as one of the most critical components. Development of efficient vibration based fault detection methods for these bearings requires a thorough understanding of their vibration signature. Much work has been done to study the vibration properties of healthy planetary gear sets and to identify fault frequencies in fixed-axis bearings. However, vibration characteristics of planetary gear sets containing localized planet bearing defects (spalls or pits) have not been studied so far. In this paper, we propose a novel analytical model of a planetary gear set with ring gear flexibility and localized bearing defects as two key features. The model is used to simulate the vibration response of a planetary system in the presence of a defective planet bearing with faults on inner or outer raceway. The characteristic fault signature of a planetary bearing defect is determined and sources of modulation sidebands are identified. The findings from this work will be useful to improve existing sensor placement strategies and to develop more sophisticated fault detection algorithms.
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Jacobs, K. J. P., A. Khaled, M. Stucchi, T. Wang, M. Gonzalez, K. Croes et I. De Wolf. « Light-Induced Capacitance Alteration for Nondestructive Fault Isolation in TSV Structures for 3D Integration ». Dans ISTFA 2016. ASM International, 2016. http://dx.doi.org/10.31399/asm.cp.istfa2016p0406.
Texte intégralRésumé :
Abstract We report on a new non-destructive electrical fault isolation (EFI) technique to localize interconnection failures in through-silicon via (TSV) structures for three-dimensional (3-D) integration. The scanning optical microscopy (SOM) technique is based on light-induced capacitance alteration (LICA) and uses localized photon probing of TSV interconnect capacitance to localize interruptions of electrical connectivity. The technique is applicable to passivated devices and allows rapid, efficient, and non-destructive fault isolation at wafer level. We describe the physics behind signal generation of the technique and demonstrate the TSV photocapacitance effect. We further demonstrate the LICA technique on open failed TSV daisy chain structures and confirm our results with microprobing and voltage contrast measurements in a scanning electron microscope (SEM).
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Kankar, P. K., Satish C. Sharma et S. P. Harsha. « Rolling Element Bearing Fault Diagnosis Using Complex Gaussian Wavelet ». Dans ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-40476.
Texte intégralRésumé :
This paper is focused on fault diagnosis of bearings due to localized defects i.e. spall on the bearing components, which is essential to the design of high performance rotor bearing system. The methodology proposed in this paper for fault diagnosis of rolling element bearings, utilizes autocorrelation of raw vibration signals to reduce the dimension of vibration signals with minimal loss of significant frequency content. Dimension of vibration signal is reduced to 10% with negligible loss of information. To extract most appropriate features from auto-correlated vibration signals and for effective classification of faults, vibration signals are decomposed using complex Gaussian wavelet. Total 150 signals of healthy and defective bearings at rotor speeds 250, 500, 1000, 1500 and 2000 rpm with three loading conditions are considered. 1-D continuous wavelet coefficients of these samples are calculated at the seventh level of decomposition (27 scales for each sample). Maximum Energy to Shannon Entropy ration criterion is used to determine scale corresponding to characteristic defect frequency. Statistical features are extracted from the wavelet coefficients corresponding to selected scales. Finally, bearing faults are classified using Support Vector Machine (SVM) method. The test results show that the SVM can be used efficiently for bearing fault classification. It is also observed that classification accuracy is improved by using autocorrelation.
Rapports d'organisations sur le sujet "LOCALISED FAULTS"
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Wozniakowska, P., D. W. Eaton, C. Deblonde, A. Mort et O. H. Ardakani. Identification of regional structural corridors in the Montney play using trend surface analysis combined with geophysical imaging. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329795.
Texte intégralRésumé :
Induced (anthropogenic) earthquakes are caused by reactivation of pre-existing faults due to human activities, including hydraulic fracturing and saltwater disposal. The Montney play, the pre-eminent shale gas play in Canada, contains localized regions with relatively high geological susceptibility to induced seismicity. Identification of potential seismogenic structures is hindered because published fault maps in the Montney play are often focused on small areas, leading to inconsistencies when these are compiled across the region. We have developed a regional framework based on structural corridors: complex, multi-strand faults systems. A three-step structural interpretation workflow was used, including seismic and structural interpretation along with trend surface analysis (TSA). This approach was used to identify 34 structural corridors in NE BC and NW Alberta.
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Paul, C., et J. F. Cassidy. Seismic hazard investigations at select DND facilities in Southwestern British Columbia : subduction, in-slab, and crustal scenarios. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/331199.
Texte intégralRésumé :
Southwest British Columbia has some of the highest seismic hazard in Canada and is home to facilities owned by the Department of National Defence which support operations on the west coast of Canada. The potential impact of seismic hazards on these government facilities are investigated here. The hazard is from three primary sources: subduction interface, crustal and in-slab earthquakes. NRCan, in consultation with DRDC have produced representative earthquake scenarios for each of these sources. The subduction scenario we constructed was an M8.9 earthquake extending along the entire Cascadia Subduction Zone from 4 to 18 km depth. We used an M6.8 earthquake occurring along a 30 km fault at between 52 and 60 km depth below Boundary Bay to represent in-slab events. The final scenario, representing a crustal source, was an M6.4 along the central 47 km of the Leech River Valley-Devil's Mountain Fault system. We found that the Cascadia subduction scenario dominated the shaking hazard over much of the study region. Meanwhile, the in-slab and crustal scenarios have higher but more localized hazards in Vancouver and Victoria. In addition to the primary ground motion hazard, we also examined secondary seismic hazards: secondary amplification effects, landslides, liquefaction, surface ruptures, tsunami, flooding, fire, and aftershocks. Each of the secondary hazards had varying impacts depending on the scenario and locations within the region.
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Kwun, H. L51694 Investigation of Techniques for Bulk Stress Measurement on Exposed Pipelines-Phases I and II. Chantilly, Virginia : Pipeline Research Council International, Inc. (PRCI), octobre 1993. http://dx.doi.org/10.55274/r0010318.
Texte intégralRésumé :
Differential movement of a buried pipeline resulting from terrain instabilities such as subsidence, fault slippage, frost heave, ice scouring, soil movement, and landslide can create localized areas of high stress in a pipeline. These areas may be susceptible to mechanical failure and therefore may compromise the structural integrity of the line. Nondestructive testing (NDT) methods that can detect high-stress regions and measure the magnitude of the stress in the pipeline are needed to determine if or when remedial action must be taken to prevent stress-related damage. The areas of high stress can compromise the integrity of the pipeline, despite the fact that the highly stressed areas may not be readily detectable. �This report describes two phases of development for a nonintrusive technique to quantify the local, throughwall average axial stress in an exposed pipe. The technique selected for evaluation and development is a low-frequency, electromagnetic technique, called multiparameter magnetic measurement (MPMM). MPMM is a combination of existing magnetic techniques including magnetic hysteresis measurement, nonlinear harmonic analysis, and multiparameter correlation. The work included both a proof-of-principle demonstration of the technique using samples of grade X-42, X-46, and X-52 pipe (Phase I), and further determination of practical applicability of the MPMM technique (Phase II). Phase II focused on evaluating the variability of magnetic response to stress among five samples of grade X-42 pipe.
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Arcone, Steven, James Lever, Laura Ray, Benjamin Walker, Gordon Hamilton et Lynn Kaluzienski. Ground-penetrating radar profiles of the McMurdo shear zone, Antarctica, acquired with an unmanned rover : interpretation of crevasses, fractures, and folds within firn and marine ice. Engineer Research and Development Center (U.S.), décembre 2021. http://dx.doi.org/10.21079/11681/42620.
Texte intégralRésumé :
The crevassed firn of the McMurdo shear zone (SZ) within the Ross Ice Shelf may also contain crevasses deep within its meteoric and marine ice, but the surface crevassing prevents ordinary vehicle access to investigate its structure geophysically. We used a lightweight robotic vehicle to tow 200- and 40 MHz ground-penetrating radar antennas simultaneously along 10 parallel transects over a 28 km² grid spanning the SZ width. Transects were generally orthogonal to the ice flow. Total firn and meteoric ice thickness was approximately 160 m. Firn crevasses profiled at 400 MHz were up to 16 m wide, under snow bridges up to 10 m thick, and with strikes near 35°–40° to the transect direction. From the top down, 200- MHz profiles revealed firn diffractions originating to a depth of approximately 40 m, no discernible structure within the meteoric ice, a discontinuous transitional horizon, and at least 20 m of stratified marine ice; 28–31 m of freeboard found more marine ice exists. Based on 10 consecutive transects covering approximately 2.5 km², we preliminarily interpreted the transitional horizon to be a thin saline layer, and marine ice hyperbolic diffractions and reflections to be responses to localized fractures, and crevasses filled with unstratified marine ice, all at strikes from 27° to 50°. We preliminarily interpreted off nadir, marine ice horizons to be responses to linear and folded faults, similar to some in firn. The coinciding and synchronously folded areas of fractured firn and marine ice suggested that the visibly unstructured meteoric ice beneath our grid was also fractured, but either never crevassed, crevassed and sutured without marine ice inclusions, or that any ice containing crevasses might have eroded before marine ice accretion. We will test these interpretations with analysis of all transects and by extending our grid and increasing our depth ranges.