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Mohamed, E. A., i 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, nr 3 (10.06.2005): 939–70. http://dx.doi.org/10.5194/hessd-2-939-2005.
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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 i 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, nr 21-22 (2.05.2019): 7212–23. http://dx.doi.org/10.1177/0954406219846153.
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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., i 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, nr 1 (8.02.2006): 49–64. http://dx.doi.org/10.5194/hess-10-49-2006.
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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 i 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, nr 2 (15.01.2020): 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 i 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, nr 3 (10.03.2023): 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 i Yan Kei Chiang. "Fault detection of wheel in wheel/rail system using kurtosis beamforming method". Structural Health Monitoring 19, nr 2 (14.06.2019): 495–509. http://dx.doi.org/10.1177/1475921719855444.
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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 i Klaus Reicherter. "Hanging-wall colluvial cementation along active normal faults". Quaternary Research 88, nr 1 (lipiec 2017): 39–59. http://dx.doi.org/10.1017/qua.2017.32.
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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., i S. Abe. "Earthquake statistics in a Block Slider Model and a fully dynamic Fault Model". Nonlinear Processes in Geophysics 11, nr 5/6 (17.11.2004): 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, i 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, nr 10 (9.01.2019): 1424–32. http://dx.doi.org/10.1177/1350650118822362.
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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 i M. Lalmi. "The application of the cyclic coherence for distributed planet fault detection in planetary gears". International Journal of Condition Monitoring 8, nr 2 (1.04.2018): 58–63. http://dx.doi.org/10.1784/204764218823029075.
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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.
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Chen, Jianlong, Yu Zhou, Gan Chen i Ming Hao. "Decades of Ground Deformation in the Weihe Graben, Shaanxi Province, China, in Response to Various Land Processes, Observed by Radar Interferometry and Levelling". Remote Sensing 13, nr 12 (17.06.2021): 2374. http://dx.doi.org/10.3390/rs13122374.
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Ground deformation is usually used as direct evidence for early warning of geological hazards. The Weihe Graben, located in the southern margin of the Ordos Plateau, is surrounded by many active faults. Earthquakes (e.g., the 1556 Huaxian M 8 earthquake), mine accidents and ground fissures are the major hazards that pose great threats to this densely populated region. In order to characterise both tectonic and anthropogenic activities in the Weihe Graben, we use Envisat data from 2003 to 2010 and Sentinel-1 data from 2014 to 2021, combined with levelling data from 1970 to 2014, to investigate the long-term ground deformation. We generate four InSAR rate maps using the small-baseline subset (SBAS) algorithm. The uncertainties of the InSAR rates are 1–2 mm/year by calculating the differences between the InSAR and levelling measurements. From the deformation time series, we found that most of the faults surrounding the Weihe Graben move at a relatively slow rate (<3 mm/year). Elastic dislocation modelling based on the InSAR and levelling data yields a slip rate of 2.3 ± 0.3 mm/year for the Huashan Fault, the seismogenic fault for the 1556 Huaxian earthquake. Anthropogenic deformation is much stronger than the tectonic deformation. We identified localised subsidence of 12 mines with a deformation rate ranging from 5 to 17 mm/year. The cities of Xi’an and Xianyang also show evident subsidence, which is likely to be caused by groundwater extraction. Land subsidence in Xi’an has slowed down from an average rate of 10–20 mm/year between 2003 and 2010 to about 5–10 mm/year between 2017 and 2020, but in Xianyang, subsidence has increased dramatically in the past five years from 1 mm/year to 7 mm/year. This is because new industrial and urban development centres have gradually moved from Xi’an to Xianyang. We identified a region bounded by the Kouzhen-Guanshan and Fufeng-Liquan Faults with strong subsidence, as a result of excessive extraction of groundwater. To quantify the effects of crustal groundwater unloading on faults, we calculated the static Coulomb stress changes on the two faults and found that Coulomb stress changes are localised in the upper 5 km with a magnitude of 0.01–0.02 bar/year. The Coulomb stress changes might be large enough (0.1 bar) to affect local seismicity if such excessive extraction of groundwater continued for 10 years.
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Tsioumpri, Eleni, Bruce Stephen i Stephen D. J. McArthur. "Weather Related Fault Prediction in Minimally Monitored Distribution Networks". Energies 14, nr 8 (7.04.2021): 2053. http://dx.doi.org/10.3390/en14082053.
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Power distribution networks are increasingly challenged by ageing plant, environmental extremes and previously unforeseen operational factors. The combination of high loading and weather conditions is responsible for large numbers of recurring faults in legacy plants which have an impact on service quality. Owing to their scale and dispersed nature, it is prohibitively expensive to intensively monitor distribution networks to capture the electrical context these disruptions occur in, making it difficult to forestall recurring faults. In this paper, localised weather data are shown to support fault prediction on distribution networks. Operational data are temporally aligned with meteorological observations to identify recurring fault causes with the potentially complex relation between them learned from historical fault records. Five years of data from a UK Distribution Network Operator is used to demonstrate the approach at both HV and LV distribution network levels with results showing the ability to predict the occurrence of a weather related fault at a given substation considering only meteorological observations. Unifying a diverse range of previously identified fault relations in a single ensemble model and accompanying the predicted network conditions with an uncertainty measure would allow a network operator to manage their network more effectively in the long term and take evasive action for imminent events over shorter timescales.
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Nekrasov, E. M. "Localisation of gold ores in faults of different types". Proceedings of higher educational establishments. Geology and Exploration, nr 6 (19.03.2020): 33–43. http://dx.doi.org/10.32454/0016-7762-2019-6-33-43.
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The results of the author’s and general works of domestic and foreign geologists, who studied the location of the largest gold deposits in fault zones, characterised by the structure of ore-bearing zones and the concentration of reserves of ores and gold of different scale in them, are presented. The main reasons for such differences are considered. The longest faults on our planet are regional shifts. They are continuously traced for hundreds (up to 1,400) of kilometres along the boundaries of gold-bearing belts and provinces. However, gold ore deposits are located in their zones at extremely limited (point) intervals not exceeding 3—5 km. They are always enclosed between ancient transverse or oblique-oriented fractures of deep, most likely mantle, formation and penetration. In all mineralised faults, gold ore bodies are localised in various geological and structural traps, which are considered in the article and are reflected in the plans and sections. The crossing nodes of regional shifts, as well as overfaults and faults of transverse faults (and dislocations), act as the main promising objects in the deposits search and exploration. Obviously, such nodes should be considered as direct signs of the possible evidence of gold ores. The internal structure of the world leader, gold-bearing Muruntaussky (North-East) local shift (Uzbekistan), studied in detail by the author and other geologists, is given as an example.
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Samsu, Anindita, Weronika Gorczyk, Timothy Chris Schmid, Peter Graham Betts, Alexander Ramsay Cruden, Eleanor Morton i Fatemeh Amirpoorsaeed. "Selective inversion of rift basins in lithospheric-scale analogue experiments". Solid Earth 14, nr 8 (29.08.2023): 909–36. http://dx.doi.org/10.5194/se-14-909-2023.
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Abstract. Basin inversion is commonly attributed to the reverse reactivation of basin-bounding normal faults. This association implies that basin uplift and inversion-related structures are mainly controlled by the frictional behaviour of pre-existing faults and associated damage zones. In this study, we use lithospheric-scale analogue experiments of orthogonal extension followed by shortening to explore how the flow behaviour of ductile layers underneath rift basins promote or suppress basin inversion. Our experiments show that the rheology of the ductile lower crust and lithospheric mantle, modulated by the imposed bulk strain rate, determine (1) basin distribution in a wide rift setting and (2) strain accommodation by fault reactivation and basin uplift during subsequent shortening. When the ductile layers deform uniformly during extension (i.e. stretching) and shortening (i.e. thickening), all of the basins are inverted. When deformation in the ductile layers is localised during extension (i.e. necking) and shortening (i.e. folding), only some basins – which are evenly spaced apart – are inverted. We interpret the latter as selective basin inversion, which may be related to the superposition of crustal-scale and lithospheric-scale boudinage during the previous basin-forming extensional phase and/or folding of the ductile layers during shortening.
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Moshrefzadeh, Ali, i Alessandro Fasana. "Planetary gearbox with localised bearings and gears faults: simulation and time/frequency analysis". Meccanica 52, nr 15 (2.05.2017): 3759–79. http://dx.doi.org/10.1007/s11012-017-0680-7.
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Amalanathan, Arputhasamy Joseph, Ramanujam Sarathi, Maciej Zdanowski, Ravikrishnan Vinu i Zbigniew Nadolny. "Review on Gassing Tendency of Different Insulating Fluids towards Transformer Applications". Energies 16, nr 1 (2.01.2023): 488. http://dx.doi.org/10.3390/en16010488.
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This paper reports the critical reviews on the gassing tendency of different insulating fluids along with the precautionary measures to be considered during their fault diagnosis in transformer insulation. The experimental techniques and procedures for identifying the gassing due to electrical and thermal stress along with the stray gassing phenomenon has been elucidated. The different interpretation schemes used for determining the faults in transformers results in unexpected errors when the historical data relating to mineral oil is used for the other alternative fluids. Mineral oil and natural ester show a positive gassing tendency compared to synthetic ester which exhibit a negative gassing tendency. The stray gases are mostly due to breakage of C-C bonds under normal operating temperature of transformer. Among the different hydrocarbons, hydrogen and ethylene are more predominantly formed under lower temperatures. The silicone oil and ester fluids are more stable even under localised hot spots simulated observing a lesser gassing compared to the mineral oil. The impact of additives along with the oxygen and water content in the insulating fluids can lead to the stray gas’s causing confusion towards the identification of actual faults occurring in transformers. Furthermore, the regeneration of insulating fluids using different adsorbents reduces the gassing tendency depending on the number of cycles used for its reclamation.
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O'Brien, G. W., M. Morse, D. Wilson, P. Quaife, J. Colwell, R. Higgins i C. B. Foster. "MARGIN-SCALE, BASEMENT-INVOLVED COMPARTMENTALISATION OF AUSTRALIA'S NORTH WEST SHELF: A PRIMARY CONTROL ON BASIN-SCALE RIFT, DEPOSITION AL AND REACTIVATION HISTORIES". APPEA Journal 39, nr 1 (1999): 40. http://dx.doi.org/10.1071/aj98003.
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Australia's North West Shelf is segmented into four discrete margin-scale compartments which have distinct rift and reactivation histories. Two of the margin segments, the Carnarvon and Bonaparte compartments, are very wide (500–600 km), marginal plateau systems, whereas the other two segments, the Canning and Browse compartments, are narrower and steeper. The boundaries between individual rift compartments appear to be controlled by Proterozoic fracture systems.The Browse-Bonaparte transition zone is a major, northwest-trending Proterozoic fracture system which has a series of igneous intrusions along its length. These intrusions are located where the fracture system is cut by younger, northeast-trending extensional faults. This transition zone is a margin-scale fault relay zone, with intense fault overlap along the transition resulting in the zone being a long-lived, syn-rift high. Moreover, the transition zones between adjacent wide and narrow margins are prime locations for the entry point of siliciclastics into the rift or post-rift margin system. As a result, well-developed channel systems often cut through these boundaries and high quality reservoirs (particularly low-stand fans) are developed.Neogene fault reactivation, associated with convergence of the Australasian and Eurasian plates, is evident along the North West Shelf. The style of this reactivation is, however, closely controlled by the margin- scale architecture. In the Browse and Carnarvon basins, Neogene inversion is common, but at the leading edge of the collisional system, the Bonaparte compartment, the fault style is exclusively extensional. It appears that lithospheric flexure, associated with localised foreland development (i.e. the Timor Trough), has been the driving mechanism for the extensional faulting within the Bonaparte compartment. Crustal convergence seems to have been accommodated completely by thrusting on the northwestern margin of Timor and by foreland formation. In contrast, the Browse and Carnarvon compartments lacked a 'buffering' foreland system and, being adjacent to rigid and thin oceanic crust which transmits stress well over long distances, the inversional stresses were transmitted directly into these compartments.As a result of these margin-scale processes, the Bonaparte compartment is characterised by a thin regional seal (often 100 ms) on Neogene extensional faults—a combination which strongly favours fault seal failure and trap breach. In contrast, the Browse compartment is characterised by thick seals and small displacement Neogene faults, and thus the probability of fault seal failure is much less.
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Ciftci, Bozkurt, Laurent Langhi, Silvio Giger, Julian Strand, Louise Goldie-Divko, John Miranda i Geoffrey O'Brien. "Top seal bypass risk due to fracture systems, nearshore/onshore Gippsland Basin". APPEA Journal 52, nr 1 (2012): 397. http://dx.doi.org/10.1071/aj11032.
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The extensional architecture of the Gippsland Basin was modified by a phase of contractional deformation during the Oligocene—Pleistocene postdating the main subsidence phase of the basin. This deformation caused local inversion and folding, which modified the depocentre geometry and controlled deformation of the syn-kinematic regional top-seal—the Lakes Entrance Formation. Accordingly, there is spatial variation of deformation intensity and lithofacies distribution, the latter of which possibly affected the strain accommodation behaviour of the Lakes Entrance Formation. These factors are critical and locally detrimental to seal capacity. In this study, the volume of shale distribution of the Lakes Entrance Formation was modelled and various parameters of the seismic-scale faults were computed, including shale gouge ratio, slip tendency and dilation tendency. Sub-seismic deformation was captured by strain and curvature attributes at the Latrobe unconformity, which carries the most intense imprint of the deformation phase. These parameters were correlated to known hydrocarbon seepage and leakage indicators in the basin, which could be related either to: (i) localised deformation along fault zones; or, (ii) to distributed deformation separated from the fault zones. There is generally a good match between the anomalous values of the computed parameters and the location of leakage indicators. For fault-related localised deformation zones, the match of the parameters ranks in the following order: shale gouge ratio (95%), strain (84%), curvature (84%) and slip tendency (74%). By combining these four parameters, a fault-related leakage assessment factor (FLAF) was defined and mapped across the study area. Match ratio of the parameters used to capture distributed deformation separated from the fault zones are ranked in the following order: curvature (100%), strain (100%) and volume of shale (83%). These parameters were also combined to define an ‘other’ leakages assessment factor (OLAF) and mapped across the study area. FLAF and OLAF maps are consistent with known leakage/seepage indicators in the basin and are indicative of additional areas with potential risk for top seal bypass. These risk maps provide useful input to CO2 storage and hydrocarbon exploration efforts in the basin.
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El Ghali, Abdessalem, Claude Bobier i Noureddine Ben Ayed. "Significance of the E-W fault system in the geodynamic evolution of the Tunisian Alpine Chain foreland. Example of the Sbiba-Cherichira fault system in Central Tunisia". Bulletin de la Société Géologique de France 174, nr 4 (1.07.2003): 373–81. http://dx.doi.org/10.2113/174.4.373.
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Abstract The recent sedimentary basins in Central Tunisia correspond to a set of depocenters with complex geometry which are bounded by E-W, N070 and N-S brittle structures. These bordering faults, active during Eocene and Cretaceous times, have been rejuvenated at the end of the Neogene and during Quaternary in a relay pattern system associated with compressive and extensive deformations according to the alternance of extension and compression phases (Tortonian Atlasic Phase of compression, post tectonic top Miocene-early Pleistocene extension associated to the rifting of the Tyrrhenian Basin, and Pleistocene Phase of compression). These tectonic regime changes involve subsidence inversions. Moreover, the neotectonic study carried out along the strike-slip faults corridories and their associated structures enable us : – to precise the timing of the tectonic deformations ; – to establish tectono-sedimentary relationships of Mio-Plio-Quaternary age. Introduction : geodynamical context and objectives of the study. – In Central Tunisia as in the whole Maghreb [Piqué et al., 1998 ; Piqué et al., 2002], the Mesozoic and Cenozoic evolution of sedimentary basins is largely controlled by tectonic heredity due to rejuvenation of basement discontinuities. In fact, previous studies have shown that the normal kinematics activity of The Sbiba-Cherichira fault has governed the opening and the distribution of the Cretaceous and the Eocene basins evolving in a globally extensive tectonic regime [Boltenhagen, 1981 ; El Ghali, 1993]. These old tectonics is proven, also, by the interpretation of NNE-SSW seismic profiles through this collapsed zone [Ben Ayed, 1986, fig. 3] and who reveal that subsidence had been active during the Lower Cretaceous and continued up to the Albian. In the late Miocene and early Quaternary, following the Langhian collision of Sardinia against the Northern Platform of Tunisia [Cohen et al., 1980], the Atlasic and Villafranchian Phases of compression are the most important. They were responsible for the formation of important N040° to N070°E Atlasic folds , N040° to N090°E thrusts , the opening of N120° to N150° E basins parallel to the shortening axis and E-W strike slip fault [Burollet, 1956 ; Ben Ayed, 1986]. In this paper, we present and discuss results of research carried out in the Sbiba-Cherichira area. This research combines interpretation of sedimentological observations and microtectonic or structural field studies [El Ghali et Batik, 1992] carried out along and near the Sbiba-Cherichira faults system, which corresponds to two separated master faults (fig. 2): – the « Southern Sbiba Fault » developed to the west with a direction N090°E which acted as is the southern boundary of the “Sbiba Trough” subsident area as early as the Albian (fig. 3) ; – the “Cherichira Fault” developed to the north-east with a direction N070°E. These faults are connected by the N040°E Labaied-Trozza Fault. Tortonian tectonic activity. – During Tortonian compression (orientation of the shortening axis N120°to N140°E) [Burollet, 1956 ; Ben Ayed, 1986 ; Philip et al., 1986 ; Martinez et al., 1990], many transformations were induced in the studied area (fig. 4a). In fact, the E-W faults of Sbiba and the N070 to N90°E faults of Cherichira, disposed in left relay, were reactivated as dextral strike-slip faults inducing simultaneous distensive deformations (normal faults, grabens, half-grabens…) and compressive ones (folds, reverse faults, overlappings….) localised at fracturing extremity [El Ghali, 1993]. Compressive structures. – The brittle structures are associated with ductile deformations of two types : *The first one corresponds to en echelon folds including : – to the south of the E-W Sbiba Fault, in J. Tiouacha and J. Labaied, Eocene and Neogene strata which are involved in hectometric folds with a N040° to N060°E axial direction (fig. 4a) and an axial westward dip changing from 05° to 60°E ; – to the west of the J. Rebeiba fault, Lutetian and Oligocene to Lower Miocene Strata which are affected by hectometric folds with a N070° to N090°E direction (fig. 4a) and an axial westward dip, changing from 05°to 20°E [El Ghali, 1993]. All these folds are abruptly cut up by the master faults and they can be interpreted as en echelon fault propagation folds. * The second includes plurikilometric folds parallel to the strike slip faults : – the E-W anticline of J. Labaied due to the transpression responsible for reactivation of the southern Sbiba Fault with a dextral strike slip component (fig. 4a); – the N040°E anticline of J. Trozza and the N070°E anticline of J. Cherichira respectively associated with the Trozza-Labaied fault and the Cherichira fault. Because of their orientation approximatively normal to the shortening axis, these faults are reactivated reversed faults giving fault-bend folds [Suppe, 1983] thrusted to the SE with a decollement level in Triassic evaporites extruded along the fault between J. M’Rhila and J. Cherichira (fig. 4a). Distensive structures : syntectonic depocenters associated to dextral strike-slip faults. – The dextral strike-slip faults extremities develop as normal faults N140 to N160°E in the dampening zone (fig. 4a). The east and west endings of Sbiba strike slip fault are two distensive extremities the opening mecanism of which is compatible with that of a megasplit basin at a strike-slip extremity [Harding, 1973 ; Odonne, 1981 ; Granier, 1985 ; Faugère et al., 1986…]. Top Miocene to early Pleistocene tectonic activity. – During upper top Miocene and early Pleistocene times, the Sbiba Trough was characterized by a subsidence more important than in any other place in Tunisia and was filled by continental deposits of the Segui Formation (conglomerates, sands, black clays and lacustrine limestones, fig. 5). Subsidence (500m near Haffouz, 3000m in Sbiba Trough, fig. 4b) was controlled by the activity of synsedimentary normal and strike-slip faults, forming small grabens, monoclinal grabens N090° to N130°E trending often cut by the Sbiba Fault (figs. 4b and 7). This extension can be considered as a post-tectonic extension relative to the Atlasic phase of compression, the orientation of the tensile axis being the same. Pleistocene tectonic activity. – In Central Tunisia, a NNW-SSE compressive phase, intervening in early Quaternary, has been demonstrated out [Burollet, 1956 ; Ben Ayed, 1986 ; Philip et al., 1986]. This “Villafranchian phase” follows distensive strike-slip tectonics of top Miocene Lowermost Pleistocene [El Ghali, 1993] and involves subsidence inversion. This phase is manifested by reverse dextral strike-slip faults on E-W segments (Sbiba and Ain Grab faults, fig. 4c) and by SE vergence overlappings on the NE-SW segments of J. Trozza (fig. 6) and N070°E ones of Cherichira (fig. 8). In other places the top Miocene-early Pleistocene deposits of the Segui Formation are folded, producing in the Sbiba basin N070° to N090°E en echelon folds (fig. 4c) with westward or eastward axial dipping between 05° and 15°. In Jebel Ain Grab area, the folds are overturned and locally thrusted northwards producing a morphostructural dam. This latter limits to the south a sag filled with fluviatile and lacustrine deposits (fig. 9). Comparison with neighbouring regions and conclusions. – The Sbiba-Cherichira faults system correspond to an en-echelon strike slip fault inherited from a basement discontinuity. It recorded most of the main tectonic processes which affected the southern margin of the Tethys. In Central Tunisia, this faults system constitutes an evolution model of one of the major scars which affects the sedimentary cover and controls basins distribution and evolution since the Cretaceous to the Quaternary. * The Tortonian compressional episode corresponding to the Compression Atlasic Phase described from the Rif in Morocco to northern Tunisia [Viguier et al., 1980 ; Philip, 1983 ; Ben Ayed, 1986 ; Morel, 1989 ; Aite, 1995 ; Piqué et al., 2002]. The N120° to N130°E orientation of the shortening axis induced the most important transpression which has triggered the rejuvenation of the Sbiba-Cherichira system as a very active fault driving halokinesis of Triassic evaporites and large development of brittle and folded structures associated to wrench faulting activity as in the eastern platform of Tunisia (fig. 10) [Ellouz, 1984]. * During the top Miocene-early Pleistocene postectonic extension, the rejuvenation of older faults generated a multidirectional extension near the Sbiba-Cherichira faults system as in northern Tunisian platform [Tricart et al., 1994] or in the north-eastern platform and in the strait of Sicily [Bobier et Martin, 1976 ; Ellouz, 1984]. In the Sbiba and Haffouz basins, the multidirectional extension is responsible for the development, along the N070°E dextral strike slip faults and N120°E left lateral strike slip faults, of depocenters for the Segui Formation which is superimposed to Middle Cretaceous subident areas [El Ghali, 1993]. * The Upper-Pleistocene episode which corresponds to the Villafranchian Phase with a N170° to N180°E shortening axis in agreement with the convergence of the European and African Plate and very well documented from the southern margin of Grande Kabilie [Aite, 1995] to northern Tunisia [Ben Ayed, 1986]. Near Sbiba it induced formation of folds, thrusts or reversed faults forming morphostructural dams in which fluvio-lacustrine deposits are accumulated.
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Basak, D., i S. Waghmare. "Comparative study of 36 mm-diameter rope in five aerial ropeway installations using a non-destructive method". Insight - Non-Destructive Testing and Condition Monitoring 62, nr 10 (1.10.2020): 598–600. http://dx.doi.org/10.1784/insi.2020.62.10.598.
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Visual inspection of wire rope is the most conventional method but it can be inadequate, especially for long rope. Non-destructive evaluation using magnetic methods is an important means for monitoring the performance of haulage rope. A rope tester, used to scan ropes, identifies the loss of metallic area (LMA) and discontinuities such as broken wires or localised faults (LFs). Performing non-destructive evaluation on a regular basis acts as a useful tool for recording the degradation of rope in the installation. In this paper, an attempt has been made to compare the conditions of 36 mm-diameter rope in five aerial ropeway installations using a non-destructive method.
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Holford, Simon, Richard Hillis, Ian Duddy, Paul Green, Martyn Stoker, Adrian Tuitt, Guillaume Backé, David Tassone i Justin MacDonald. "Cenozoic post-breakup compressional deformation and exhumation of the southern Australian margin". APPEA Journal 51, nr 1 (2011): 613. http://dx.doi.org/10.1071/aj10044.
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We present results from a margin-wide analysis of the history of post-breakup Cenozoic compressional deformation and related exhumation along the passive southern margin of Australia, based on a regional synthesis of seismic, stratigraphic and thermochronological data. The Cenozoic sedimentary record of the southern margin contains regional unconformities of intra-Lutetian and late Miocene–Pliocene age, which coincide with reconfigurations of the boundaries of the Indo-Australian Plate. Seismic data show that post-breakup compressional deformation and sedimentary basin inversion—characterised by reactivation of syn-rift faults and folding of post-rift sediments—is pervasive from the Gulf St Vincent to Gippsland basins, and occurred almost continually since the early- to mid-Eocene. Inversion structures are absent from the Bight Basin, which we interpret to be the result of both the unsuitable orientation of faults for reactivation with respect to post-breakup stress fields, and the colder, stronger lithosphere that underlies that part of the margin. Compressional deformation along the southeastern margin has mainly been accommodated by reactivation of syn-rift faults, resulting in folds with varying ages and amplitudes in the post-rift Cenozoic succession. Many hydrocarbon fields in the Otway and Gippsland basins are located in these folds, the largest of which are often associated with substantial localised exhumation. Our results emphasise the importance of constraining the timing of Cenozoic compression and exhumation in defining hydrocarbon prospectivity of the southern margin.
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Papathanasopoulos, Dimitrios A., Konstantinos N. Giannousakis, Evangelos S. Dermatas i Epaminondas D. Mitronikas. "Vibration Monitoring for Position Sensor Fault Diagnosis in Brushless DC Motor Drives". Energies 14, nr 8 (16.04.2021): 2248. http://dx.doi.org/10.3390/en14082248.
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A non-invasive technique for condition monitoring of brushless DC motor drives is proposed in this study for Hall-effect position sensor fault diagnosis. Position sensor faults affect rotor position feedback, resulting in faulty transitions, which in turn cause current fluctuations and mechanical oscillations, derating system performance and threatening life expectancy. The main concept of the proposed technique is to detect the faults using vibration signals, acquired by low-cost piezoelectric sensors. With this aim, the frequency spectrum of the piezoelectric sensor output signal is analyzed both under the healthy and faulty operating conditions to highlight the fault signature. Therefore, the second harmonic component of the vibration signal spectrum is evaluated as a reliable signature for the detection of misalignment faults, while the fourth harmonic component is investigated for the position sensor breakdown fault, considering both single and double sensor faults. As the fault signature is localized at these harmonic components, the Goertzel algorithm is promoted as an efficient tool for the harmonic analysis in a narrow frequency band. Simulation results of the system operation, under healthy and faulty conditions, are presented along with the experimental results, verifying the proposed technique performance in detecting the position sensor faults in a non-invasive manner.
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Birdus, Sergey, Vincent Ganivet, Alexey Artemov, Ray Teakle i Paul Phythian. "Estimation of uncertainties in fault lateral positioning on 3D PSDM seismic image: an example from the North West Shelf". APPEA Journal 56, nr 2 (2016): 556. http://dx.doi.org/10.1071/aj15062.
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This extended abstract presents a two-step sequence to estimate uncertainties in lateral positioning of fault planes on 3D PSDM (pre-stack depth migration) seismic images. This analysis can be applied to any localised detail on a seismic image but, in the majority of geological settings, it is most important for the faults. The first step provides an approximate evaluation of what causes the uncertainties, how the uncertainties are distributed in a 3D space, and what to expect within target zones. The authors assume that every complex detail within a 3D PSDM velocity model causes some uncertainties to the seismic image below. Thus, the uncertainties at a target level depend on the complexity of the overburden and the seismic acquisition parameters. At this step a qualitative 3D volume of lateral fault position uncertainties is created. In the second step the authors focus on a single fault of practical interest. Based on the results of the first step, the authors modify the existing 3D PSDM anisotropic velocity model by introducing additional anomalies that cause maximal changes to the lateral position of the fault on seismic image. Then the authors iteratively re-migrate a small sub-volume around the fault and check the PSDM images and residual moveout. The objective is to find out how far the velocity variations can move the image of the fault and still satisfy available seismic data. The second step gives more reliable quantitative estimations of the impact of velocity on fault positioning. A real multi-azimuth 3D seismic dataset from the North West Shelf is used to illustrate this sequence.
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Woods, Richard J., Sara K. McBride, Liam M. Wotherspoon, Sarah Beavan, Sally H. Potter, David M. Johnston, Thomas M. Wilson i in. "Science to emergency management response". Bulletin of the New Zealand Society for Earthquake Engineering 50, nr 2 (30.06.2017): 329–37. http://dx.doi.org/10.5459/bnzsee.50.2.329-337.
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The M7.8 Kaikōura Earthquake in 2016 presented a number of challenges to science agencies and institutions throughout New Zealand. The earthquake was complex, with 21 faults rupturing throughout the North Canterbury and Marlborough landscape, generating a localised seven metre tsunami and triggering thousands of landslides. With many areas isolated as a result, it presented science teams with logistical challenges as well as the need to coordinate efforts across institutional and disciplinary boundaries. Many research disciplines, from engineering and geophysics to social science, were heavily involved in the response. Coordinating these disciplines and institutions required significant effort to assist New Zealand during its most complex earthquake yet recorded. This paper explores that effort and acknowledges the successes and lessons learned by the teams involved.
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Demurtas, Matteo, Steven A. F. Smith, Elena Spagnuolo i Giulio Di Toro. "Frictional properties and microstructural evolution of dry and wet calcite–dolomite gouges". Solid Earth 12, nr 3 (5.03.2021): 595–612. http://dx.doi.org/10.5194/se-12-595-2021.
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Abstract. Calcite and dolomite are the two most common minerals in carbonate-bearing faults and shear zones. Motivated by observations of exhumed seismogenic faults in the Italian Central Apennines, we used a rotary-shear apparatus to investigate the frictional and microstructural evolution of ca. 3 mm thick gouge layers consisting of 50 wt % calcite and 50 wt % dolomite. The gouges were sheared at a range of slip rates (30 µm s−1–1 m s−1), displacements (0.05–0.4 m), and a normal load of 17.5 MPa under both room-humidity and water-dampened conditions. The frictional behaviour and microstructural evolution of the gouges were strongly influenced by the presence of water. At room humidity, slip strengthening was observed up to slip rates of 0.01 m s−1, which was associated with gouge dilation and the development of a 500–900 µm wide slip zone cut by Y-, R-, and R1-shear bands. Above a slip rate of 0.1 m s−1, dynamic weakening accompanied the development of a localised < 100 µm thick principal slip zone preserving microstructural evidence for calcite recrystallisation and dolomite decarbonation, while the bulk gouges developed a well-defined foliation consisting of organised domains of heavily fractured calcite and dolomite. In water-dampened conditions, evidence of gouge fluidisation within a fine-grained principal slip zone was observed at a range of slip rates from 30 µm s−1 to 0.1 m s−1, suggesting that caution is needed when relating fluidisation textures to seismic slip in natural fault zones. Dynamic weakening in water-dampened conditions was observed at 1 m s−1, where the principal slip zone was characterised by patches of recrystallised calcite. However, local fragmentation and reworking of recrystallised calcite suggests a cyclic process involving formation and destruction of a heterogeneous slip zone. Our microstructural data show that development of well-defined gouge foliation under the tested experimental conditions is limited to high velocities (>0.1 m s−1) and room humidity, supporting the notion that some foliated gouges and cataclasites may form during seismic slip in natural carbonate-bearing faults.
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Ma, Svieda M., Dawn A. Kellett, Laurent Godin i Michael J. Jercinovic. "Localisation of the brittle Bathurst fault on pre-existing fabrics: a case for structural inheritance in the northeastern Slave craton, western Nunavut, Canada". Canadian Journal of Earth Sciences 57, nr 6 (czerwiec 2020): 725–46. http://dx.doi.org/10.1139/cjes-2019-0100.
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The north–northwest-striking Bathurst fault in the northeastern Slave craton displaced the 1.9 Ga Kilohigok basin and the ca. 2.02–1.96 Ga Thelon tectonic zone, and projects beneath the 1.7 Ga Thelon basin where unconformity-associated uranium deposits are spatially associated with basement faults. Here we investigate the deformation–temperature–time history of the Bathurst fault rocks using structural and microstructural observations paired with U–(Th–)Pb and 40Ar/39Ar geochronology. Highly strained hornblende-bearing granitoid rocks, the predominant rock type on the northeastern side of the Bathurst fault in the study area, show ambiguous sense of shear suggesting flattening by coaxial deformation. Quartz and feldspar microstructures suggest ductile deformation occurred at ≥500 °C. Along the main fault trace, brittle features and hydrothermal alteration overprint the pervasive ductile flattening fabric. In situ U–Th–Pb dating of synkinematic monazite suggests ductile fabric formation at ca. 1933 ± 4 Ma and ca. 1895 ± 11 Ma, and zircon from a cross-cutting dyke constrains the brittle deformation to ≤1839 ± 14 Ma. 40Ar/39Ar dating of fabric-defining minerals yield cooling ages of ca. 1920–1900 Ma and ca. 1900–1850 Ma for hornblende and muscovite, respectively, and a maximum cooling age of ca. 1840 Ma for biotite. We suggest the ca. 1933–1895 Ma ductile flattening fabric developed during orthogonal collision and indentation of the Slave craton into the Thelon tectonic zone and Rae craton. Brittle deformation on the Bathurst fault was localised parallel to the ductile flattening fabric after ca. 1840 Ma and preceded Thelon basin deposition. Brittle deformation features in Bathurst fault rocks preserve evidence for fluid–rock interaction and enhanced basement permeability, suggesting the fault is a possible conduit structure for mineralising fluids.
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O'Brien, G. W., M. A. Etheridge, J. B. Willcox, M. Morse, P. Symonds, C. Norman i D. J. Needham. "THE STRUCTURAL ARCHITECTURE OF THE TIMOR SEA, NORTH-WESTERN AUSTRALIA: IMPLICATIONS FOR BASIN DEVELOPMENT AND HYDROCARBON EXPLORATION". APPEA Journal 33, nr 1 (1993): 258. http://dx.doi.org/10.1071/aj92019.
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The initial rifting in the Timor Sea, north-western Australia, took place in the Late Devonian to Early Carboniferous, with the development of the NWtrending Petrel Sub-basin. This rift system was compartmentalised by NE-trending accommodation zones which divided the sub-basin into discrete segments. In each segment, a lower plate rift margin, characterised by large displacement, low angle extensional faults, lay opposite an upper plate, or ramp, rift margin, characterised by small displacement, high angle flexural faults. Switching in the 'polarity' of the rift system took place across major, NE-trending accommodation zones.Part of this rift system was overprinted in the Late Carboniferous to Early Permian by the Westralian Super-Basin rift system, which developed on a NE trend, orthogonal to that of the underlying Petrel Sub-basin. The entire Vulcan Sub-basin and Sahul Platform region developed as part of an upper plate rift margin, with the Vulcan Sub-basin probably forming initially as a small flexural feature in the inboard part of the upper plate rift margin. The rift margin consisted of a linked array of NW-trending accommodation zones and NE-trending normal faults; pre-existing, NW-, NE- and NS-trending ?Proterozoic fracture systems controlled, at least to some extent, the geometry of the rift system that developed. The island of Timor probably developed as a major intra-rift high, or possibly a marginal plateaux, at this time. Thermal subsidence phase sedimentation continued until the Late Triassic, resulting in the deposition of 10 to perhaps 14 km of relatively unstructured sediments.Three major reactivation events affected the Timor Sea during the Mesozoic. These were: compression in the Late Triassic to Early Jurassic, extension in the Late Callovian to Early Oxfordian (late Middle to early Late Jurassic) and compression in the Tithonian/Berriasian (Late Jurassic/Early Cretaceous). These events all reactivated the pre-existing ?Proterozoic/ Petrel Sub-basin/Westralian Super-Basin structural architecture in a variety of ways. In the Petrel Sub-basin, reactivation was localised almost exclusively over the lower plate rift margins, leading to the formation of anticlines and ultimately, salt diapirism.In the Vulcan Sub-basin, all of the significant hydrocarbon discoveries appear to be preferentially located either along, or at the intersection of, NW- and NS-trending fault sets with the NE/ENE-trending grain. This is probably because the intersections of these Proterozoic/Late Carboniferous-Early Permian fault sets respond in a particularly complex fashion to the varying Mesozoic stress directions. In a qualitative fashion, this observation does provide a number of largely untested exploration 'fairways' within the Vulcan Sub-basin.
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Bishop, D. J., i G. W. O'Brien. "A MULTI-DISCIPLINARY APPROACH TO DEFINITION AND CHARACTERISATION OF CARBONATE SHOALS, SHALLOW GAS ACCUMULATIONS AND RELATED COMPLEX NEAR-SURFACE SEDIMENTARY STRUCTURES IN THE TIMOR SEA". APPEA Journal 38, nr 1 (1998): 93. http://dx.doi.org/10.1071/aj97005.
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A major exploration program is being undertaken by the AC/P16 Joint Venture in the central Timor Sea, northwestern Australia. Its safe and successful execution is critically dependant on the early definition and characterisation of both the numerous carbonate shoals in the area and the complex bathymetry. This was accomplished via the acquisition of environmental, high-resolution bathymetric, 2D and 3D seismic and airborne laser fluorosensor (ALF) data. Multi-disciplinary integration and analysis of these data have enabled mapping and 3D visualisation of the shoals, and the creation of a 3D velocity model for depth conversion. Seismic amplitude anomalies and chaotic seismic reflectors, which increase in areal extent toward the sea floor, have been interpreted as being due to shallow gas. These gas accumulations are also associated with soft-sediment gravity slides in the shallow sub-surface which exhibit thrust imbrication in the contractional toes and are linked to listric extensional faults. The high resolution bathymetric data have provided images of a disturbed sea floor in several of the areas which are affected by shallow gas: craters, troughs, ridges and mounds can be explained by the localised venting of gas at the sea floor. These gas accumulations are located above basin-scale faults, which are inferred to provide migration paths from more deeply buried source rocks. ALF anomalies mapped at the sea surface, and sea floor grab samples containing petrogenic hydrocarbons, also provide evidence that hydrocarbons are presently leaking from the sea floor.
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Benmouiza, Khalil. "Grid Connected PV Systems Fault Detection using K-Means Clustering Algorithm". International Journal of Emerging Technology and Advanced Engineering 13, nr 5 (13.05.2023): 73–83. http://dx.doi.org/10.46338/ijetae0523_07.
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—Efficiency in photovoltaic (PV) energy production is significantly influenced by various electrical, environmental, and manufacturing-related factors. These variables often lead to a range of PV generator faults, compromising the system's performance and the overall grid's safety. The current fault detection methods can be complex and resource-intensive. In this paper, we propose a novel and efficient grid-connected PV system fault detection mechanism using the k-means clustering algorithm. Our approach categorizes the possible faults based on clustering the output PV and grid powers under healthy and faulty conditions. A comparison between centroid locations of both conditions leads to fault categorization. The findings demonstrate the efficacy of the proposed technique for addressing localized faults in grid-tied PV systems without the need for complicated calculations. The technique is both cost-effective and accurate, with a straightforward application that can be easily adopted by all stakeholders. This method enables users to safeguard their PV system's health and ensure the more comprehensive grid's safety.
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Griffiths, Luke, Jérémie Dautriat, Ismael Vera Rodriguez, Kamran Iranpour, Guillaume Sauvin, Joonsang Park, Joel Sarout i in. "Inferring microseismic source mechanisms and in situ stresses during triaxial deformation of a North-Sea-analogue sandstone". Advances in Geosciences 49 (4.09.2019): 85–93. http://dx.doi.org/10.5194/adgeo-49-85-2019.
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Abstract. Monitoring microseismic activity provides a window through which to observe reservoir deformation during hydrocarbon and geothermal energy production, or CO2 injection and storage. Specifically, microseismic monitoring may help constrain geomechanical models through an improved understanding of the location and geometry of faults, and the stress conditions local to them. Such techniques can be assessed in the laboratory, where fault geometries and stress conditions are well constrained. We carried out a triaxial test on a sample of Red Wildmoor sandstone, an analogue to a weak North Sea reservoir sandstone. The sample was coupled with an array of piezo-transducers, to measure ultrasonic wave velocities and monitor acoustic emissions (AE) – sample-scale microseismic activity associated with micro-cracking. We calculated the rate of AE, localised the AE events, and inferred their moment tensor from P-wave first motion polarities and amplitudes. We applied a biaxial decomposition to the resulting moment tensors of the high signal-to-noise ratio events, to provide nodal planes, slip vectors, and displacement vectors for each event. These attributes were then used to infer local stress directions and their relative magnitudes. Both the AE fracture mechanisms and the inferred stress conditions correspond to the sample-scale fracturing and applied stresses. This workflow, which considers fracture models relevant to the subsurface, can be applied to large-scale geoengineering applications to obtain fracture mechanisms and in-situ stresses from recorded microseismic data.
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Morel, Cristina, Baptiste Le Gueux, Sébastien Rivero i Saad Chahba. "Currents Analysis of a Brushless Motor with Inverter Faults—Part II: Diagnostic Method for Open-Circuit Fault Isolation". Actuators 12, nr 6 (2.06.2023): 230. http://dx.doi.org/10.3390/act12060230.
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In this paper, a brushless motor with a three-phase inverter is investigated under healthy and multiple open-circuit faults. The occurrence of faults in an inverter will lead to atypical characteristics in the current measurements. This is why many usual entropies and multiscale entropies have been proposed to evaluate the complexity of the output currents by quantifying such dynamic changes. Among this multitude of entropies, only some are able to differentiate between healthy and faulty open-circuit conditions. In addition, another selection is made between these entropies in order to improve diagnostic speed. After the fault detection based on the mean values, the open-circuit faults are localized based on the fault diagnostic method. The simulation results ensure the ability of these entropies to detect and locate open-circuit faults. Moreover, they are able to achieve fault diagnostics for a single switch, double switches, three switches, and even four switches. The diagnostic time to detect and to isolate faults is between 10.85 ms and 13.67 ms. Then, in order to prove the ability of the fault diagnostic method, a load variation is performed under the rated speed conditions of the brushless motor. The validity of the method is analyzed under different speed values for a constant torque. Finally, the fault diagnostic method is independent from power levels.
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Jahan, Ismot, John Castagna, Michael Murphy i M. Amin Kayali. "Fault detection using principal component analysis of seismic attributes in the Bakken Formation, Williston Basin, North Dakota, USA". Interpretation 5, nr 3 (31.08.2017): T361—T372. http://dx.doi.org/10.1190/int-2016-0209.1.
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Seismic fault detection using principal component analysis (PCA) is an effective method for interpreting fault distribution and orientations in the Bakken Formation. The PCA fault attribute indicates significantly different, and geologically more plausible, 3D fault distributions than conventional seismic attributes, such as curvature. The PCA fault attribute has identified different fault patterns in the Upper, Middle, and Lower Bakken members and the Three Forks Formation. Two distinct fault trends in approximately 40°–50° northeast–southwest and 50°–60° northwest–southeast directions are observed in the Bakken Formation in the study area, and they are apparent on the strike and dip attributes derived from the PCA fault attribute. Fault cuts interpreted from missing well-log sections correlate well with the PCA fault attribute. Seismically derived fault orientations correlate with borehole image log data in the horizontal wells. Crossing conjugate faults observed on the fault dip attribute may result in the widening of the faulted area and localized thinning of the rock sequence where the faults intersect, and this could potentially enhance permeability along the fault strike.
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Erkül, Fuat, Sibel Tatar Erkül, Hatice Seval Manap i Cihan Çolak. "An extensional and transtensional origin of elongated magmatic domes and localised transfer faults in the northern Menderes metamorphic core complex, western Turkey". Geodinamica Acta 29, nr 1 (1.01.2017): 139–59. http://dx.doi.org/10.1080/09853111.2017.1343523.
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Pownall, J. M., R. Hall i I. M. Watkinson. "Extreme extension across Seram and Ambon, eastern Indonesia: Evidence for Banda slab rollback". Solid Earth Discussions 5, nr 1 (17.04.2013): 525–607. http://dx.doi.org/10.5194/sed-5-525-2013.
Pełny tekst źródłaStreszczenie:
Abstract. The island of Seram, which lies in the northern part of the 180°-curved Banda Arc, has previously been interpreted as a fold-and-thrust belt formed during arc-continent collision, which incorporates ophiolites intruded by granites thought to have been produced by anatexis within a metamorphic "sole". However, new geological mapping and a re-examination of the field relations cause us to question this model. We instead propose that there is evidence for recent N–S extension that has caused the high-temperature exhumation of hot mantle peridotites, granites, and granulites (the "Kobipoto Complex") beneath low-angle lithospheric detachment faults. Greenschist- to lower-amphibolite facies metapelites and amphibolites of the Tehoru Formation, which comprise the hanging wall above the detachment faults, were overprinted by sillimanite-grade metamorphism, migmatisation and limited localised diatexis to form the Taunusa Complex. Highly aluminous metapelitic garnet + cordierite + sillimanite + spinel + corundum + quartz granulites exposed in the Kobipoto Mountains (central Seram) are intimately associated with the peridotites. Spinel + quartz inclusions in garnet, which indicate that peak metamorphic temperatures for the granulites likely approached 900 °C, confirm that peridotite was juxtaposed against the crust at typical lithospheric mantle temperatures and could not have been part of a cooled ophiolite. Some granulites experienced slight metatexis, but the majority underwent more advanced in situ anatexis to produce widespread granitic diatexites characterised by abundant cordierite and garnet xenocrysts and numerous restitic sillimanite + spinel "clots". These Mio-Pliocene "cordierite granites", which are present throughout Ambon, western Seram, and the Kobipoto Mountains in direct association with peridotites, demonstrate that the extreme extension required to have driven Kobipoto Complex exhumation must have occurred along much of the northern Banda Arc. In central Seram, smeared lenses of peridotites are incorporated with a major left-lateral strike-slip shear zone (the "Kawa Shear Zone"), demonstrating that strike-slip motions likely initiated shortly after the mantle had been partly exhumed by detachment faulting and that the main strike-slip faults may themselves be reactivated and steepened low-angle detachments. The Kobipoto Mountains represent a left-lateral pop-up structure that has facilitated the final stages of exhumation of the high-grade Kobipoto Complex through overlying Mesozoic sedimentary rocks. On Ambon, Quaternary "ambonites" (cordierite + garnet dacites) are evidently the volcanic equivalent of the cordierite granites as they also contain granulite-inherited xenoliths and xenocrysts. The geodynamic driver for mantle exhumation along the detachment faults and strike-slip faulting in central Seram is very likely the same – we interpret the extreme extension to be the result of eastward slab rollback into the Banda Embayment as outlined by the latest plate reconstructions for Banda Arc evolution.
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Łuczak, Dominik, Stefan Brock i Krzysztof Siembab. "Fault Detection and Localisation of a Three-Phase Inverter with Permanent Magnet Synchronous Motor Load Using a Convolutional Neural Network". Actuators 12, nr 3 (15.03.2023): 125. http://dx.doi.org/10.3390/act12030125.
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Fault-tolerant control of a three-phase inverter can be achieved by performing a hardware reconfiguration of the six-switch and three-phase (6S3P) topology to the four-switch and three-phase (4S3P) topology after detection and localisation of the faulty phase. Together with hardware reconfiguration, the SVPWM algorithm must be appropriately modified to handle the new 4S3P topology. The presented study focuses on diagnosing three-phase faults in two steps: fault detection and localisation. Fault detection is needed to recognise the healthy or unhealthy state of the inverter. The binary state recognition problem can be solved by preparing a feature vector that is calculated from phase currents (ia, ib, and ic) in the time and frequency domains. After the fault diagnosis system recognises the unhealthy state, it investigates the signals to localise which phase of the inverter is faulty. The multiclass classification was solved by a transformation of the three-phase currents into a single RGB image and by training a convolutional neural network. The proposed methodology for the diagnosis of three-phase inverters was tested based on a simulation model representing a laboratory test bench. After the learning process, fault detection was possible based on a 128-sample window (corresponding to a time of 0.64 ms) with an accuracy of 99 percent. In the next step, the localisation of selected individual faults was performed on the basis of a 256-sample window (corresponding to a time of 1.28 ms) with an accuracy of 100 percent.
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Nekrasov, E. M., i L. A. Dorozhkina. "Sukhoy log gold deposit and possible prospecting for ores on its flanks". Proceedings of higher educational establishments. Geology and Exploration 63, nr 2 (5.11.2020): 21–34. http://dx.doi.org/10.32454/0016-7762-2020-63-2-21-34.
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Background. Experimental exploitation of ores from the Sukhoi Log deposit has shown that its geology and structure requires elucidation.Aim. To study the geology and structure of the Sukhoi Log deposit and to determine the main mineralisation patterns in the plan, on the flanks and at depth. This information can be useful when mining gold both directly at the deposit and when prospecting new deposits on its flanks.Materials and methods. The existing maps, diagrams, sketches and block diagrams describing ore bodies and their behaviour in plan and at depth were used. A new structural layout of mineralisation at the Sukhoi Log deposit, both on its flanks and at depth was built.Results. The gold mineralisation in the Sukholozhskaya and Verninsko-Nevskaya ore-bearing areas is controlled by various elements of the fracture structure. At the same time, in the Sukholozhskaya area, the mineralisation is confined to a thick zone of a sublatitudinal shingled thrust-fault zone, in places accommodating a narrow strip of small faults, slip planes and fracturing in the northwestern direction. The fracture strip intersects sub-latitudinally laying Riphean argillaceous-shale rocks of the Khomolkhin formation approximately in the middle part of the field. The shingled thrust-fault zone accommodates the fissure faults, which open during mineralisation of the north-west extension, and flattens out. Its thickness in some places reaches 130 m. In the curved and flattened thrust interval, an ore gold-arsenopyrite-pyrite-quartz formation is localised, morphologically resembling a “thick pillow” with a thickness of 130 m. It bends and gently plunges in the north-north-east direction. The bulk of gold reserves is contained in this ore formation. The ores of the vein-disseminated type, veinlet and vein formations are the richest formations. Between them, the dissemination of gold-bearing pyrite and subordinate arsenopyrite is always manifested. The boundary of industrial mineralisation is determined by the density of the interveinous ore.On the western flank of the deposit, within the bounds of another — Ugakhan — deposit, vein and vein gold-quartz-pyrrhotite ores are found at a deeper level. Here, the search for Sukholozhsky pyrite-quartz ores (if they even existed) is not promising, since they were eroded long time ago, and the liberated gold was concentrated in placers. Prospecting is promising only along the Bezymyanny ore-controlling fault, which directly limits the western flank of the Sukholozhskoye deposit.The mineralisation of the Verninsk-Nevsky area is controlled by the Verninsky Fault of the east–north-east extension and separated by a series of single feathering ore-bearing overthrust zones of the east-west extension. To the east, this mineralisation gradually decreases. The search for the Sukholozhsk type ores is more promising on the eastern side of the Nyrli river, 2 km east of the fault of the same name and 7 km north of the Verninskoye deposit near a small, poorly explored area with commercial gold mineralization, marked on the deposit map with a sign TM.Conclusion. The main geological and structural laws of the localisation of gold ores were determined, which could be useful when conducting exploration works on the flanks of the deposit.
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Liu, Yang, Zhang Dengbo, Yang Yueting i Ruquan Liang. "Fault Characteristics Analysis of High-Speed Train Transmission Systems". Shock and Vibration 2022 (21.11.2022): 1–15. http://dx.doi.org/10.1155/2022/7109507.
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The high-speed train speed has a higher requirement for stability and operating safety with its operating speed increasing. The main focus of this paper is on the fault characteristics analysis of a high-speed train transmission system. The governing equation and boundary conditions of the transmission system are derived using the finite element method, in which a Timoshenko beam element is introduced to represent the wheelset shaft, and a rigid mass element is utilized to represent the gears, bearings, and wheels. To investigate the vibration response mechanism of a high-speed train transmission system, the critical speed of the system and its modal response are given. According to the types of high-speed train component fault features, the local fault features of gear, bearing, and wheelset are given. Healthy and faulty systems with localized faults in gear, bearing, and wheelset are studied. The characteristics of amplitude and frequency are verified numerically and the transmission characteristics of signal and relation are explained when there is local fault defect in the system. The results show that under different fault types, the time domain response of the system has obvious periodic impulse response faults, and the fault frequency band characteristic distribution is different in the frequency domain response. The simulation results are consistent with the experimental results.
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Benn, Keith, Francis Odonne, Sharon K. Y. Lee i Ken Darcovich. "Analogue scale models of pluton emplacement during transpression in brittle and ductile crust". Earth and Environmental Science Transactions of the Royal Society of Edinburgh 91, nr 1-2 (2000): 111–21. http://dx.doi.org/10.1017/s0084255900006021.
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Analogue experiments were used to investigate pluton emplacement during transpression in a layered crust. Models consisted of (1) a silicone gum-PbO suspension as analogue magma, (2) a silicone gum-Pb suspension as a basal ductile layer, and (3) an overlying sand pack representing brittle crust. The models were transpressed at 3 mm/hr causing the extrusion of the analogue magma from a progressively closing slot, and its emplacement into the ductile layer. The thicknesses of the layers were critical in controlling the shapes of intrusions and the structures that developed in the brittle overburden. Thicker sand packs led to flattened, symmetrical laccolith-shaped intrusions and the nucleation of one oblique thrust in the sand pack above the extremity of the intrusion. Thinner sand packs led to thicker, asymmetrical laccolith-like intrusions with uplift of the overburden on an oblique thrust, and the formation of a shallow graben in the extrados of a bending fold. Reducing the thickness of the basal ductile layer resulted in a larger number of shear zones in the sand pack, and structural geometries approaching those produced in experiments involving only a brittle analogue crust and no ductile layer. Shear zones in the sand pack were localised by intrusions, and also played a key role in displacing analogue brittle crust to make space for intrusions. The results suggest that tectonic forces may play an important role in displacing blocks of crust during pluton emplacement in transpressional belts. They also suggest that pluton shapes, and the geometries and kinematics of emplacement-related shear zones and faults, may depend on the depth of emplacement. In nature, depending on the structural level exposed in the map plane, faults and shear zones that helped make space for emplacement may not appear to be spatially associated with the pluton.
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Khelif, Mohamed Amine, Azeddine Bendiabdellah i Bilal Djamal Eddine Cherif. "A Combined RMS-MEAN Value Approach for an Inverter Open-Circuit Fault Detection". Periodica Polytechnica Electrical Engineering and Computer Science 63, nr 3 (5.04.2019): 169–77. http://dx.doi.org/10.3311/ppee.13605.
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Currently, with the power electronics evolution, a major research axis is oriented towards the diagnosis of converters supplying induction machines. Indeed, a converter such as the inverter is susceptible to have structural failures such as faulty leg and/or open-circuit IGBT faults. In this paper, the detection of the faulty leg and the localization of the open-circuit switch of an inverter are investigated. The fault detection technique used in this work is based essentially upon the monitoring of the root mean square (RMS) value and the calculation of the mean value of the three-phase currents. In the first part of the paper work, the faulty leg is detected by monitoring the RMS value of the three-phase currents and comparing them to the nominal value of the phase current. The second part, the open-circuit IGBT fault is localized simply by knowing the polarity of the calculated mean value current of the faulty phase. The work is first accomplished using simulation work and then the obtained simulation results are validated by experimental work conducted in our LDEE laboratory to illustrate the effectiveness, simplicity and rapidity of the proposed technique.
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Wang, Wei Feng, Chuan Hua Zhu, Yan Bin Qing i Xin Jian Shan. "Research on Transverse Faults in the Longmenshan Fault Zone, China". Advanced Materials Research 1010-1012 (sierpień 2014): 1380–86. http://dx.doi.org/10.4028/www.scientific.net/amr.1010-1012.1380.
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The Longmenshan fault zone has been a research hotspot, but fewer scholars have paid attention to its transverse faults. According to the analysis of regional tectonic, seismic activities, geomorphic features, remote sensing images, and deep geophysical data, combined with field studies, the existence, distribution and type of the transverse faults in the Longmenshan fault zone were demonstrated. Research shows that there are 9 transverse faults that lie parallel to each other approximately at ~50km intervals in the Longmenshan fault zone. And transverse faults can be divided into regional transverse faults and localized transverse faults with NW strike, nearly EW strike and nearly SN strike.
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Pownall, J. M., R. Hall i I. M. Watkinson. "Extreme extension across Seram and Ambon, eastern Indonesia: evidence for Banda slab rollback". Solid Earth 4, nr 2 (24.09.2013): 277–314. http://dx.doi.org/10.5194/se-4-277-2013.
Pełny tekst źródłaStreszczenie:
Abstract. The island of Seram, which lies in the northern part of the 180°-curved Banda Arc, has previously been interpreted as a fold-and-thrust belt formed during arc-continent collision, which incorporates ophiolites intruded by granites thought to have been produced by anatexis within a metamorphic sole. However, new geological mapping and a re-examination of the field relations cause us to question this model. We instead propose that there is evidence for recent and rapid N–S extension that has caused the high-temperature exhumation of lherzolites beneath low-angle lithospheric detachment faults that induced high-temperature metamorphism and melting in overlying crustal rocks. These "Kobipoto Complex" migmatites include highly residual Al–Mg-rich garnet + cordierite + sillimanite + spinel + corundum granulites (exposed in the Kobipoto Mountains) which contain coexisting spinel + quartz, indicating that peak metamorphic temperatures likely approached 900 °C. Associated with these residual granulites are voluminous Mio-Pliocene granitic diatexites, or "cordierite granites", which crop out on Ambon, western Seram, and in the Kobipoto Mountains and incorporate abundant schlieren of spinel- and sillimanite-bearing residuum. Quaternary "ambonites" (cordierite + garnet dacites) emplaced on Ambon were also evidently sourced from the Kobipoto Complex migmatites as demonstrated by granulite-inherited xenoliths. Exhumation of the hot peridotites and granulite-facies Kobipoto Complex migmatites to shallower structural levels caused greenschist- to lower-amphibolite facies metapelites and amphibolites of the Tehoru Formation to be overprinted by sillimanite-grade metamorphism, migmatisation, and limited localised anatexis to form the Taunusa Complex. The extreme extension required to have driven Kobipoto Complex exhumation evidently occurred throughout Seram and along much of the northern Banda Arc. The lherzolites must have been juxtaposed against the crust at typical lithospheric mantle temperatures in order to account for such high-temperature metamorphism and therefore could not have been part of a cooled ophiolite. In central Seram, lenses of peridotites are incorporated with a major left-lateral strike-slip shear zone (the "Kawa Shear Zone"), demonstrating that strike-slip motions likely initiated shortly after the mantle had been partly exhumed by detachment faulting and that the main strike-slip faults may themselves be reactivated and steepened low-angle detachments. The geodynamic driver for mantle exhumation along the detachment faults and strike-slip faulting in central Seram is very likely the same; we interpret the extreme extension to be the result of eastward slab rollback into the Banda Embayment as outlined by the latest plate reconstructions for Banda Arc evolution.
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Verberne, Berend A., Oliver Plümper i Christopher J. Spiers. "Nanocrystalline Principal Slip Zones and Their Role in Controlling Crustal Fault Rheology". Minerals 9, nr 6 (28.05.2019): 328. http://dx.doi.org/10.3390/min9060328.
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Principal slip zones (PSZs) are narrow (<10 cm) bands of localized shear deformation that occur in the cores of upper-crustal fault zones where they accommodate the bulk of fault displacement. Natural and experimentally-formed PSZs consistently show the presence of nanocrystallites in the <100 nm size range. Despite the presumed importance of such nanocrystalline (NC) fault rock in controlling fault mechanical behavior, their prevalence and potential role in controlling natural earthquake cycles remains insufficiently investigated. In this contribution, we summarize the physical properties of NC materials that may have a profound effect on fault rheology, and we review the structural characteristics of NC PSZs observed in natural faults and in experiments. Numerous literature reports show that such zones form in a wide range of faulted rock types, under a wide range of conditions pertaining to seismic and a-seismic upper-crustal fault slip, and frequently show an internal crystallographic preferred orientation (CPO) and partial amorphization, as well as forming glossy or “mirror-like” slip surfaces. Given the widespread occurrence of NC PSZs in upper-crustal faults, we suggest that they are of general significance. Specifically, the generally high rates of (diffusion) creep in NC fault rock may play a key role in controlling the depth limits to the seismogenic zone.
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Handique, Mousum, Jantindra Kumar Deka i Santosh Biswas. "Fault Localization Scheme for Missing Gate Faults in Reversible Circuits". ACM Transactions on Design Automation of Electronic Systems 27, nr 4 (31.07.2022): 1–29. http://dx.doi.org/10.1145/3503539.
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This article introduces a fault localization method to extract the exact location of single and multiple missing gate faults in reversible \( k \) -CNOT -based circuits. The primary target of the proposed method is to obtain the complete test set for localizing faults in \( k \) -CNOT circuits. We propose a fault localization algorithm to construct a fault localization tree that can be used to find equivalent and non-equivalent faults. For the non-equivalent faults, the test sequences can be obtained from the fault localization tree that uniquely localizes the non-equivalent faults. Finally, this article presents the experimental results and comparative analysis with existing works.
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Koehl, Jean-Baptiste P., i Jhon M. Muñoz-Barrera. "From widespread Mississippian to localized Pennsylvanian extension in central Spitsbergen, Svalbard". Solid Earth 9, nr 6 (21.12.2018): 1535–58. http://dx.doi.org/10.5194/se-9-1535-2018.
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Abstract. In the Devonian–Carboniferous, a rapid succession of clustered extensional and contractional tectonic events is thought to have affected sedimentary rocks in central Spitsbergen, Svalbard. These events include Caledonian post-orogenic extensional collapse associated with the formation of thick Early–Middle Devonian basins, Late Devonian–Mississippian Ellesmerian contraction, and Early–Middle Pennsylvanian rifting, which resulted in the deposition of thick sedimentary units in Carboniferous basins like the Billefjorden Trough. The clustering of these varied tectonic settings sometimes makes it difficult to resolve the tectono-sedimentary history of individual stratigraphic units. Notably, the context of deposition of Mississippian clastic and coal-bearing sedimentary rocks of the Billefjorden Group is still debated, especially in central Spitsbergen. We present field evidence (e.g., growth strata and slickensides) from the northern part of the Billefjorden Trough, in Odellfjellet, suggesting that tilted Mississippian sedimentary strata of the Billefjorden Group deposited during active (Late/latest?) Mississippian extension. WNW–ESE-striking basin-oblique faults showing Mississippian growth strata systematically die out upwards within Mississippian to lowermost Pennsylvanian strata, thus suggesting a period of widespread WNW–ESE-directed extension in the Mississippian and an episode of localized extension in Early–Middle Pennsylvanian times. In addition, the presence of abundant basin-oblique faults in basement rocks adjacent to the Billefjorden Trough suggests that the formation of Mississippian normal faults was partly controlled by reactivation of preexisting Neoproterozoic (Timanian?) basement-seated fault zones. We propose that these preexisting faults reactivated as transverse or accommodation cross faults in or near the crest of transverse folds reflecting differential displacement along the Billefjorden Fault Zone. In Cenozoic times, a few margin-oblique faults (e.g., the Overgangshytta fault) may have mildly reactivated as oblique thrusts during transpression–contraction, but shallow-dipping, bedding-parallel, duplex-shaped décollements in shales of the Billefjorden Group possibly prevented substantial movement along these faults.
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Yang, Xiaoqing, Gang Yang, Qiang Zeng, Canyi Du, Xiangkun Zeng, Feifei Yu i Zhuyun Chen. "Improved Vibration Signal Models of Localized Faults of Sun Gears to Predict Modulation". Symmetry 15, nr 9 (22.08.2023): 1621. http://dx.doi.org/10.3390/sym15091621.
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The vibration modulation of the localized faults of sun gears is complicated because of the structure and motion features of planetary gearboxes. It is challenging to completely determine the vibration modulation mechanism. To address this issue, the influences of fluctuations in speed on the factors that affect vibration like the transfer path function, time-varying projection function, and meshing force were studied. Improved vibration amplitude and frequency modulation models were then established by combining the factors affecting vibration considering the speed fluctuations caused by the localized faults of sun gears. Regarding the features of vibration modulation of localized faults of sun gears, we concluded that both fault feature frequency and carrier rotational frequency modulate the harmonics of the meshing frequency, which form two groups of modulation sidebands. In addition, the harmonics of the fault feature frequency over the whole frequency range are modulated by the rotational frequency of the carrier, which is more dominant in the resonance domain. The experimental results of localized faults of sun gears strongly agree with those deduced using the proposed models. This research contributes an effective frequency indicator that can be used to confirm the condition of planetary gearboxes.
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Preuss, Simon, Jean Paul Ampuero, Taras Gerya i Ylona van Dinther. "Characteristics of earthquake ruptures and dynamic off-fault deformation on propagating faults". Solid Earth 11, nr 4 (22.07.2020): 1333–60. http://dx.doi.org/10.5194/se-11-1333-2020.
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Abstract. Natural fault networks are geometrically complex systems that evolve through time. The evolution of faults and their off-fault damage patterns are influenced by both dynamic earthquake ruptures and aseismic deformation in the interseismic period. To better understand each of their contributions to faulting we simulate both earthquake rupture dynamics and long-term deformation in a visco-elasto-plastic crust subjected to rate- and state-dependent friction. The continuum mechanics-based numerical model presented here includes three new features. First, a 2.5-D approximation is created to incorporate the effects of a viscoelastic lower crustal substrate below a finite depth. Second, we introduce a dynamically adaptive (slip-velocity-dependent) measure of fault width to ensure grid size convergence of fault angles for evolving faults. Third, fault localization is facilitated by plastic strain weakening of bulk rate and state friction parameters as inspired by laboratory experiments. This allows us to simulate sequences of episodic fault growth due to earthquakes and aseismic creep for the first time. Localized fault growth is simulated for four bulk rheologies ranging from persistent velocity weakening to velocity strengthening. Interestingly, in each of these bulk rheologies, faults predominantly localize and grow due to aseismic deformation. Yet, cyclic fault growth at more realistic growth rates is obtained for a bulk rheology that transitions from velocity-strengthening friction to velocity-weakening friction. Fault growth occurs under Riedel and conjugate angles and transitions towards wing cracks. Off-fault deformation, both distributed and localized, is typically formed during dynamic earthquake ruptures. Simulated off-fault deformation structures range from fan-shaped distributed deformation to localized splay faults. We observe that the fault-normal width of the outer damage zone saturates with increasing fault length due to the finite depth of the seismogenic zone. We also observe that dynamically and statically evolving stress fields from neighboring fault strands affect primary and secondary fault growth and thus that normal stress variations affect earthquake sequences. Finally, we find that the amount of off-fault deformation distinctly depends on the degree of optimality of a fault with respect to the prevailing but dynamically changing stress field. Typically, we simulate off-fault deformation on faults parallel to the loading direction. This produces a 6.5-fold higher off-fault energy dissipation than on an optimally oriented fault, which in turn has a 1.5-fold larger stress drop. The misalignment of the fault with respect to the static stress field thus facilitates off-fault deformation. These results imply that fault geometries bend, individual fault strands interact, and optimal orientations and off-fault deformation vary through space and time. With our work we establish the basis for simulations and analyses of complex evolving fault networks subject to both long-term and short-term dynamics.
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Cox, Randel Tom, Robert D. Hatcher, Steven L. Forman, Ronald Counts, James Vaughn, Eric Gamble, Jacob Glasbrenner, Kathleen Warrell, Narayan Adhikari i Sean Pinardi. "Synthesis of Recent Paleoseismic Research on Quaternary Faulting in the Eastern Tennessee Seismic Zone, Eastern North America: Implications for Seismic Hazard and Intraplate Seismicity". Bulletin of the Seismological Society of America 112, nr 2 (11.01.2022): 1161–89. http://dx.doi.org/10.1785/0120210209.
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ABSTRACT Causes of intraplate seismicity remain a great unsolved problem, in contrast with plate-boundary seismicity. Modern seismicity records frequent seismic activity in plate-boundary seismic zones, but in fault zones where seismic activity is not frequent, plate boundary or intraplate, resolution of prehistoric earthquake activity is critical for estimating earthquake recurrence interval and maximum expected magnitude. Thus, documenting prehistoric earthquakes is crucial for assessing earthquake hazard posed to infrastructure, including nuclear reactors and large dams. The ∼400 km long eastern Tennessee seismic zone (ETSZ), United States, is the third most active seismic zone east of the Rocky Mountains in North America, although the largest recorded ETSZ earthquake is only Mw 4.8. Ironically, it is the least studied major eastern U.S. seismic zone. Recent ETSZ field surveys revealed an 80 km long, 060°-trending corridor containing northeast-striking Quaternary thrust, strike slip, and normal faults with displacements ≥1 m. It partially overlaps a parallel trend of seismicity that extends 30 km farther southwest, suggesting this active faulting zone may extend ∼110 km within part of the ETSZ. Near Dandridge, Tennessee, a thrust fault in French Broad River alluvium records two earthquakes in the last 40,000 yr. About 50 km southwest near Alcoa, Tennessee, a thrust fault cuts Little River alluvium and records two earthquakes between 15,000 and 10,000 yr ago. About 30 km farther southwest at Vonore, Tennessee, a thrust fault displaces bedrock ≥2 m over colluvium, and alluvium is normal faulted >2 m. This corridor, just west of the Blue Ridge escarpment, overlies a steep gradient in midcrustal S-wave velocities, consistent with a basement fault at hypocentral depths. The corridor faults may be connected to a basement fault or localized coseismic faults above a blind basement fault. Our current data suggest at least two Mw≥6.5 surface rupturing events in the last 40,000 yr.
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Sibson, Richard H. "Dual-Driven Fault Failure in the Lower Seismogenic Zone". Bulletin of the Seismological Society of America 110, nr 2 (28.01.2020): 850–62. http://dx.doi.org/10.1785/0120190190.
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ABSTRACT Frictional instability leading to fault rupture may be driven by increasing differential stress or by increases in pore-fluid pressure within the rock mass. Geological evidence (from hydrothermal vein systems in exhumed faults) together with geophysical information around active faults support the localized invasion of near lithostatically overpressured hydrothermal fluids, derived from prograde metamorphism at greater depths, into lower portions of the crustal seismogenic zone at depths of about 10–15 km (250°C<T<350°C). This is especially true of compressional–transpressional tectonic regimes that lead to crustal thickening and dewatering and are better at containing overpressure. Extreme examples are associated with areas undergoing active compressional inversion where existing faults, originally formed as normal faults during crustal extension, undergo reverse-slip reactivation during subsequent shortening though poorly oriented for reactivation. Extreme fault-valve action is likely widespread in such settings with failure driven by a combination of rising fluid pressure in the lower seismogenic zone lowering fault frictional strength, as well as by rising tectonic shear stress—dual-driven fault failure. Localized overpressure affects rupture nucleation sites, but dynamic rupturing may extend well beyond the regions of intense overpressuring. Postfailure, enhanced fracture permeability along fault rupture zones promotes fault-valve discharge throughout the aftershock period, increasing fault frictional strength before hydrothermal sealing occurs and overpressures begin to reaccumulate. The association of rupture nucleation sites with concentrated fluid overpressure is consistent with selective invasion of overpressured fluid into the roots of major fault zones and with nonuniform spacing of major vein systems along exhumed brittle–ductile shear zones.
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Jost, Anne, Sophie Violette, Jean-Claude Macquar i Gilles Dromart. "Fluid palaeo-circulation generated by the Pyrenean orogeny and its potential role in the formation of lead-zinc deposits in the Cévennes region: a modelling approach". Bulletin de la Société Géologique de France 175, nr 4 (1.07.2004): 317–29. http://dx.doi.org/10.2113/175.4.317.
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Abstract Recent studies of the host rock palaeomagnetism of the lead-zinc deposits on the Cévennes margins pointed towards regional fluid circulation from the early to middle Eocene. The hypothesis has therefore been put forward that mineralising fluids might have migrated as a consequence of the Pyrenean uplift. Based on this assumption, a digital model was developed to describe this palaeo-circulation along two reconstituted cross-sections, in early Eocene times. One of them extends from the Gulf of Lion to the Les Malines deposits at the southern end of the Cévennes mountains; the other one connects the Montagne Noire to Les Malines in order to test the hypothesis of a more localised fluid circulation. The modelling of heat and fluid circulation along these cross-sections is constrained mainly by fluid-temperature data, derived from analyses of fluid inclusions. The maximum recorded temperatures are about 150°C. The METIS code (Ecole des Mines, Paris) was used to test the transport scenarios while prescribing hydrodynamic characteristics in the series that would allow fluid flow. Gravity-driven flow is initiated at a high point, either the Montagne Noire or the Pyrenees. Drainage occurs at depth. The permeable formations concerned are: Cambrian dolomite in the cross-section beginning in the Montagne Noire, and Triassic and Liassic carbonate or sandstone formations in the other one. The fluids converge at the deposit site through faults on the margins of the Cévennes horst. The highest temperatures reproduced by the digital simulations in a steady-state regime are in the order of 80°C at the deposit site for each pathway. A sensitivity test showed that higher temperatures, in the order of 150°C, could only be reached with a heat flux of 120 mW.m−2 and by optimising such parameters as permeability, aquifer geometry and thermal conductivity. However, such a parameter set does not seem geologically feasible. The modelling demonstrates that circulation must have occurred at greater depths in the case of gravity-driven fluid flow. The most probable explanation is that the fluid migrated in the deep crustal basement and that, during its ascent along the faults bordering the Cévennes heights, it mixed with basinal brines migrating through shallower aquifers.
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Bayati, Navid, Lasse Kappel Mortensen, Mehdi Savaghebi i Hamid Reza Shaker. "A Localized Transient-Based Fault Location Scheme for Distribution Systems". Sensors 22, nr 7 (1.04.2022): 2723. http://dx.doi.org/10.3390/s22072723.
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Many distribution systems have several branches with only one protection system at the upstream system. This characteristic degrades the performance of traditional fault location schemes. In this paper, a localized fault location method based on the transient behavior of fault currents by using local data is proposed. The proposed scheme uses only local current and the voltage of the upstream overcurrent relay as input data of the fault location scheme. The formulation considers fault resistance, loads, and different fault locations. Furthermore, due to the usage of transient fault current data, the proposed method locates the fault within several milliseconds with a suitable range of error. To validate the effectiveness of this method, field measurement data, obtained from a real distribution system in East Jutland, Denmark operated by Dinel A/S, are used, and extensive real-time simulations are performed. The results prove that the proposed method locates different types of faults within an appropriate time and error, which can improve the maintenance and reliability of distribution systems.