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FANG, ZIJUN, GUANSHUI XU i DAVID D. OGLESBY. "GEOMETRIC EFFECTS ON EARTHQUAKE NUCLEATION ON BENT DIP-SLIP FAULTS". International Journal of Applied Mechanics 03, nr 01 (marzec 2011): 99–117. http://dx.doi.org/10.1142/s1758825111000890.
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The geometric effects on earthquake nucleation processes on bent dip-slip faults are studied using a slip strengthening and weakening friction law implemented in a two-dimensional quasi-static boundary integral model. The results show that the bend causes normal stress variations under tectonic loading on both the upper and lower segments. These stress variations differ from those on planar faults, leading to significant effects on earthquake nucleation location and time. Earthquakes tend to nucleate at shallower locations on thrust faults and at deeper locations on normal faults for steeper dipping angles on the lower fault segments. The elapsed time until nucleation on both thrust and normal faults is increased considerably as the bend angle becomes larger. For a thrust fault with a nearly horizontal lower segment, the time until nucleation can be more than 10 times larger than that for a corresponding planar fault. These findings may provide important insights for earthquake hazard analysis by taking the fault geometry effect into account when estimating hypocenter positions and time to instability.
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Kurz, Silke Julia Birgit, Udo Welzel, Ewald Bischoff i Eric Jan Mittemeijer. "Diffraction stress analysis of highly planar-faulted, macroscopically elastically anisotropic thin films and application to tensilely loaded nanocrystalline Ni and Ni(W)". Journal of Applied Crystallography 47, nr 1 (18.01.2014): 291–302. http://dx.doi.org/10.1107/s1600576713030756.
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The presence of planar faults complicates the diffraction stress analysis enormously owing to fault-induced displacement, broadening and asymmetry of the Bragg reflections. A dedicated stress-analysis method has been developed for highly planar-faulted, fibre-textured thin films of cubic crystal symmetry, using only specific reflections for diffraction stress analysis. The effect of unjustified use of other reflections has been demonstrated in the course of application of the method to Ni and Ni(W) thin films exhibiting excessive faulting and subjected to (1) a planar, rotationally symmetric stress state and (2) a planar biaxial stress state. In case 1 the crystallite-group method has been used, whereas in case 2 the stress-analysis method based on X-ray stress factors had to be applied. The successful separation of stress- and fault-induced reflection displacements has enabled the investigation of the mechanical behaviour of Ni and Ni(W) thin films byin situstress measurements during tensile loading, thereby exposing pronounced stiffness and increased strength by alloying with W.
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Zhang, Hanlei, Hongchao Kou, Xiaolei Li, Bin Tang i Jinshan Li. "An Atomic Study of Substructures Formed by Shear Transformation in Castγ-TiAl". Advances in Materials Science and Engineering 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/675963.
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Substructures and microsegregation ofγ/γlaths are analyzed with HRTEM and HAADF-STEM. Results show that the substructures are generated during evolution of shear transformation on the(111-)plane ofγlath. At the beginning, shear transformation evolves in a singleγlath, and a superstructure intrinsic stacking fault (SISF) forms in theγlath. After the formation of the SISF, the shear transformation may evolve in two different ways. If the shear transformation evolves into neighboringγlaths, the SISF also penetrates into neighboringγlaths and a ribbon of SISFs forms. If shear transformation continues to evolve in the original lath, complex substructures begin to form in the original. If shear transformation in the original lath is homogeneous and complete, secondary twin forms which may further grow into twin intersection. Incomplete shear transformation could not form secondary twins but generates a high concentration of planar faults on the(111-)plane. These planar faults may further penetrate theγ/γlath interface, grow into adjacent laths, and form a ribbon of planar faults.
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Ojok, Tonny, John BK Duot, Majorine Namaganda, Nasra Sadiki i Michael Msabi. "Analogue Sandbox Scaled Modelling of Oblique and Orthogonal Extension Rifting in Rukwa Rift Basin, Tanzania". Tanzania Journal of Science 47, nr 5 (1.12.2021): 1660–74. http://dx.doi.org/10.4314/tjs.v47i5.15.
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Fault evolution in oblique and orthogonal rift systems in the brittle upper crust of the Rukwa rift basin was simulated using scaled sandbox modelling by varying the angle between the rift axis and the extension direction, α, through 45° and 90°, over a 10 cm displacement. The 45° oblique model exhibits a half-graben architecture bounded by a planar fault, intra-rift faults and a conjugate fault in some vertical sections. The map view of the model’s basin trends in the NW-SE direction, and is comparable with the Rukwa rift basin orientation. The 90° oblique model forms a basin structure which is orthogonal to the extension direction of the model in aerial photos. Its linear fault remains orthogonal to the extension direction, while the flexural side of the model segments into sinuous normal faults. Planar to slightly curved intra-rift faults are observed in vertical sections. The half-grabens have similar geometries in vertical sections for both models, while intra-rift faults elongate in vertical sections. The results of the oblique model are similar to natural examples of rift fault systems like the Rukwa rift. The fault geometries of the sandbox models can serve as examples for recognizing fault styles in oblique rift systems.
Keywords: Analogue Sandbox modelling, Oblique rifting, Orthogonal rifting, Tanganyika-Rukwa-Malawi Rift Segment, Rukwa Rift Basin
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Ulloa, Sirena, i Julian C. Lozos. "Surface Displacement and Ground Motion from Dynamic Rupture Models of Thrust Faults with Variable Dip Angles and Burial Depths". Bulletin of the Seismological Society of America 110, nr 6 (11.08.2020): 2599–618. http://dx.doi.org/10.1785/0120200143.
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ABSTRACT Thrust-fault earthquakes are particularly hazardous in that they produce stronger ground motion than normal or strike-slip events of the same magnitude due to a combination of hanging-wall effects, vertical asymmetry, and higher stress drop due to compression. In addition, vertical surface displacement occurs in both blind-thrust and emergent thrust ruptures, and can potentially damage lifelines and infrastructure. Our 3D dynamic rupture modeling parameter study focuses on planar thrust faults of varying dip angles, and burial depth establishes a physics-based understanding of how ground motion and permanent ground surface displacement depend on these geometrical parameters. We vary dip angles from 20° to 70° and burial depths from 0 to 5 km. We conduct rupture models on these geometries embedded in a homogeneous half-space, using different stress drops but fixed frictional parameters, and with homogeneous initial stresses versus stresses tapered toward the ground surface. Ground motions decrease as we bury the fault under homogeneous initial stresses. In contrast, under tapered initial stresses, ground motions increase in blind-thrust faults as we bury the fault, but are still the highest in emergent faults. As we steepen dip angle, peak particle velocities in the homogeneous stress case generally increase in emergent faults but decrease in blind-thrust faults. Meanwhile, ground motion consistently increases with steepening dip angle under the stress gradient. We find that varying stress drop has a considerable scalar effect on both ground motion and permanent surface displacement, whereas changing fault strength has a negligible effect. Because of the simple geometry of a planar fault, our results can be applied to understanding basic behavior of specific real-world thrust faults.
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Čeh, M., H. Gu, H. Müllejans i A. Rečnik. "Analytical electron microscopy of planar faults in SrO-doped CaTiO3". Journal of Materials Research 12, nr 9 (wrzesień 1997): 2438–46. http://dx.doi.org/10.1557/jmr.1997.0322.
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Oxide-rich planar faults within a perovskite matrix are the prevailing type of extended defects in polycrystalline SrO-doped CaTiO3. These defects form, depending on the temperature of sintering, random networks, or ordered structures. The chemistry of the polytypoid, the isolated planar faults, and the perovskite phase have been studied by spatially resolved electron energy-loss and energy-dispersive x-ray spectroscopies using a dedicated scanning transmission electron microscope. We have found that Sr ions from SrO additions preferably substitute Ca in the CaTiO3 lattice, thus forming a solid solution (Ca1–xSrx)TiO3. The surplus of Ca ions forms single and ordered CaO-rich planar faults in the host (Ca1–xSrx)TiO3 phase. Whereas the excess Ca segregates in a form of single planar faults at lower temperatures, it forms a stable polytypoidic phase at higher temperatures. For materials having up to 25 mol% of SrO additions, this phase has (Ca1–xSrx)4Ti3O10 composition, comprising a sequence of CaO faults followed by three (Ca1–xSrx)TiO3 perovskite layers. Analytical electron microscopy revealed that the composition of the single planar faults, formed at lower temperatures, is identical to that of polytypoids, which are stable at higher sintering temperatures.
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Diederichs, A., E. K. Nissen, L. J. Lajoie, R. M. Langridge, S. R. Malireddi, K. J. Clark, I. J. Hamling i A. Tagliasacchi. "Unusual kinematics of the Papatea fault (2016 Kaikōura earthquake) suggest anelastic rupture". Science Advances 5, nr 10 (październik 2019): eaax5703. http://dx.doi.org/10.1126/sciadv.aax5703.
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A key paradigm in seismology is that earthquakes release elastic strain energy accumulated during an interseismic period on approximately planar faults. Earthquake slip models may be further informed by empirical relations such as slip to length. Here, we use differential lidar to demonstrate that the Papatea fault—a key element within the 2016 Mw 7.8 Kaikōura earthquake rupture—has a distinctly nonplanar geometry, far exceeded typical coseismic slip-to-length ratios, and defied Andersonian mechanics by slipping vertically at steep angles. Additionally, its surface deformation is poorly reproduced by elastic dislocation models, suggesting the Papatea fault did not release stored strain energy as typically assumed, perhaps explaining its seismic quiescence in back-projections. Instead, it slipped in response to neighboring fault movements, creating a localized space problem, accounting for its anelastic deformation field. Thus, modeling complex, multiple-fault earthquakes as slip on planar faults embedded in an elastic medium may not always be appropriate.
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Woodward, C., J. M. MacLaren i S. Rao. "Electronic structure of planar faults in TiAl". Journal of Materials Research 7, nr 7 (lipiec 1992): 1735–50. http://dx.doi.org/10.1557/jmr.1992.1735.
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The mechanical behavior of intermetallic alloys is related to the mobility of the dislocations found in these compounds. Currently the effect of bonding on dislocation core structure and its influence on deformation behavior is not well understood. However, the unusual properties of these materials, such as the anomalous temperature dependence of flow stress observed in TiAl, are derived in part from the aspects of bonding that determine dislocation mobility. Several recent studies have suggested a particular relationship between directional bonding in TiAl and dislocation mobility. To understand better the flow behavior of high temperature intermetallics, and as a step toward bridging the gap between electronic structure and flow behavior, we have calculated the electronic structure of various planar faults in TiAl. The self consistent electronic structure has been determined using a layered Korringa Kohn Rostoker (LKKR) method which embeds the fault region between two semi-infinite perfect crystals. Calculated defect energies in stoichiometric TiAl agree reasonably well with other theoretical estimates, though overestimating the experimental (111) anti-phase boundary (APB) energy, found for Ti46Al54. We approximate the energy of the (111) APB for the Al-rich stoichiometry by calculating the energy of Al antisites near that defect plane. The calculated (111)APB energy decreases by 6% in going from stoichiometric TiAl to Ti46Al54. The overall hierarchy of fault energies is found to be associated with the number of crystal bond states that are disrupted by the introduction of the fault plane. However, the hierarchy of fault energies is inconsistent with the traditionally accepted ordering. Changes in bonding taking place in the vicinity of the planar defects are illustrated through the density of states and charge density plots. A three body atomistic model is introduced to parameterize the bonding observed in TiAl. The L10 lattice (c/a = 1.00), within a second nearest neighbor three body model, yields a (111)APB energy which is the sum of the complex and superlattice-intrinsic stacking fault energies.
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Šturm, S., A. Rečnik, C. Scheu i M. Čeh. "Formation of Ruddlesden–Popper faults and polytype phases in SrO-doped SrTiO3". Journal of Materials Research 15, nr 10 (październik 2000): 2131–39. http://dx.doi.org/10.1557/jmr.2000.0307.
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The formation of so-called Ruddlesden–Popper planar faults was studied in SrO-doped SrTiO3 for different quantities of SrO additions and sintering conditions. For small SrO additions we observed a microstructure with a uniform grain size distribution and the enrichment of SrO at the grain boundaries. Larger additions of SrO produced a microstructure of elongated grains containing random planar faults, polytypic lamellae of more or less ordered faults, and polytype loops within SrTiO3 grains. We showed that these SrTiO3 grains were elongated as a result of preferential growth of the polytypic lamellae. In addition, we discuss a correlation between the formation of planar faults embedded in the perovskite matrix at low firing temperatures and Ruddlesden–Popper phases that are stable at higher temperatures.
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Ungár, Tamás, L. Balogh i Gábor Ribárik. "Twinning, Dislocations and Grain Size in NanoSPD Materials Determined by X-Ray Diffraction". Materials Science Forum 584-586 (czerwiec 2008): 571–78. http://dx.doi.org/10.4028/www.scientific.net/msf.584-586.571.
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High resolution X-ray line profile analysis is sensitive to crystallite size, dislocation densities and character, and to planar defects, especially stacking faults or twinning. The different effects of microstructure features can be evaluated separately on the basis of the different corresponding profile functions and the different hkl dependences of line broadening. Profiles of faulted crystals consist of sub-profiles broadened and shifted according to different hkl conditions. The systematic analysis of the breadts and shifts of sub-profiles enables X-ray line profile analysis by using defect related profile functions corresponding to: (i) size, (ii) strain and (iii) planar faults, respectively. It is shown that twinning can either be enhanced or weakened by severe plastic deformation.
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Denlinger, Roger P., i Daniel R. H. O’Connell. "Evolution of Faulting Induced by Deep Fluid Injection, Paradox Valley, Colorado". Bulletin of the Seismological Society of America 110, nr 5 (18.08.2020): 2308–27. http://dx.doi.org/10.1785/0120190328.
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ABSTRACT High-pressure fluid injection into a subhorizontal confined aquifer at 4.3–4.6 km depth induced >7000 earthquakes between 1991 and 2012 within once seismically quiescent Paradox Valley in Colorado, with magnitudes up to Mw 3.9. Earthquake hypocenters expanded laterally away from the well with time, defining the margins of the aquifer pressurized by injection at the well. Within 5 km of the well, alignment of earthquake hypocenters defines strikes of nine vertical fault zones. Previous studies show that these fault zones predate injection, producing left-stepping offsets in the normal faults of the Wray-Mesa fault system that cradles Paradox Valley. Hypocenters, rakes, and strikes of 2041 well-constrained focal mechanisms show that most injection-related earthquakes occur where these vertical faults intersect the pressurized aquifer. Well-defined focal mechanisms show that this induced seismicity consists of Riedel shear faults at acute angles to the strikes of these fault zones. These small faults develop an anastomosing fault structure of focal planes along each planar fault zone, as fluid injection continues, even as their hypocenters define a single planar fault zone. Failure conditions at each hypocenter are found using a fully coupled poroelastic analysis of stress induced by fluid injection, and this analysis indicates a minimum Coulomb failure condition of 0.1 MPa. This failure condition is primarily a result of aquifer pore-fluid pressurization, as almost all well-located seismicity is within the pressurized aquifer. Reducing the rate of injection and frequent well shutdowns in the second decade nearly eliminated induced seismicity, except very near the well where gradients in pressurization are the largest. Despite these decreases in failure conditions and seismicity, some fault zones continued to produce earthquakes larger than M 3 as injection continued.
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WRIGHT, V., N. H. WOODCOCK i J. A. D. DICKSON. "Fissure fills along faults: Variscan examples from Gower, South Wales". Geological Magazine 146, nr 6 (13.07.2009): 890–902. http://dx.doi.org/10.1017/s001675680999001x.
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AbstractThe extent to which persistent, rather than transient, fissures (wide planar voids) can exist along upper crustal faults is important in assessing fault permeability to mineral and hydrocarbon-bearing fluids. Variscan (late Carboniferous) faults cutting Dinantian (Lower Carboniferous) limestones on the Gower peninsula, South Wales, host clear evidence for fissures up to several metres wide. Evidence includes dendritic hematite growth and elongate calcite growth into open voids, spar ball and cockade breccia formation, laminated sediment infill and void-collapse breccias. Detailed mapping reveals cross-cutting geometries and brecciation of earlier fissure fills, showing that fissures were formed during, rather than after, active faulting. Fissures therefore probably formed by geometric mismatch between displaced fault walls, rather than by solution widening along inactive faults.
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Twigg, Mark E., Robert E. Stahlbush, Peter A. Losee, Can Hua Li, I. Bhat i T. Paul Chow. "Overlapping Shockley/Frank Faults in 4H-SiC PiN Diodes". Materials Science Forum 527-529 (październik 2006): 383–86. http://dx.doi.org/10.4028/www.scientific.net/msf.527-529.383.
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Using light emission imaging (LEI), we have determined that not all planar defects in 4H-SiC PiN diodes expand in response to bias. Accordingly, plan-view transmission electron microscopy (TEM) observations of these diodes indicate that these static planar defects are different in structure from the mobile stacking faults (SFs) that have been previously observed in 4H-SiC PiN diodes. Bright and dark field TEM observations reveal that such planar defects are bounded by partial dislocations, and that the SFs associated with these partials display both Frank and Shockley character. That is, the Burgers vector of such partial dislocations is 1/12<4-403>. For sessile Frank partial dislocations, glide is severely constrained by the need to inject either atoms or vacancies into the expanding faulted layer. Furthermore, these overlapping SFs are seen to be fundamentally different from other planar defects found in 4H-SiC.
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Guo, Shao Cong, Mo Han Yang, Zi Rui Xing, Yi Li i Ji Qing Qiu. "Actuator Fault Detection and Isolation for Robot Manipulators with the Adaptive Observer". Advanced Materials Research 482-484 (luty 2012): 529–32. http://dx.doi.org/10.4028/www.scientific.net/amr.482-484.529.
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The fault detection and isolation (FDI) for industrial robot manipulators, subject to faults of actuator, is devised in this paper. An adaptive observer is designed to tackle the robustness problem for unknown parameters due to faults，based on a bank of state observers. By using an adaptive regulating algorithm, the observer is ensured to be stable and the estimated errors are guaranteed to converge. Experimental results are reported for a planar robot under gravity, considering partial failures of the motor torques.
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Nilsen, Halvor M., K. A. A. Lie i Jostein R. Natvig. "Accurate Modeling of Faults by Multipoint, Mimetic, and Mixed Methods". SPE Journal 17, nr 02 (7.06.2012): 568–79. http://dx.doi.org/10.2118/149690-pa.
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Summary The predominant way of modeling faults in industry-standard flow simulators is to introduce so-called transmissibility multipliers in the underlying two-point discretization. Although this approach provides adequate accuracy in many practical cases, two-point discretizations are only consistent for K-orthogonal grids and may introduce significant discretization errors for grids that severely depart from being K-orthogonal. Such grid-distortion errors can be avoided by lateral or vertical stair-stepping of deviated faults at the expense of errors in the geometrical fault description. In other words, modelers have the choice of either making (geometrical) errors by adapting faults to a grid that is almost K-orthogonal, or introducing discretization errors because of the lack of K-orthogonality if the grid is adapted to deviated faults. We propose a method for accurate description of faults in solvers based on a hybridized mixed or mimetic discretization, which also includes the MPFA-O method. The key idea is to represent faults as internal boundaries and calculate fault transmissibilities directly instead of using multipliers to modify grid-dependent transmissibilities. The resulting method is geology-driven and consistent for cells with planar surfaces and thereby avoids the grid errors inherent in the two-point method. We also propose a method to translate fault transmissibility multipliers into fault transmissibilities. This makes our method readily applicable to reservoir models that contain fault multipliers.
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McKernan, Stuart, i C. Barry Carter. "Planar defects in AIN". Proceedings, annual meeting, Electron Microscopy Society of America 47 (6.08.1989): 432–33. http://dx.doi.org/10.1017/s0424820100154135.
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Aluminum nitride has recently become the subject of much interest as a technologically useful ceramic. The mechanical strength, high thermal conductivity and large electrical resistivity and a relatively small thermal expansion coefficient, make this material extremely well suited as a semiconductor substrate material. AlN has the hexagonal, wurtzite structure rather than the cubic structure of the more common semiconductors. It is also a polar material. The characterization of microstructural defects in this material is obviously necessary to the understanding of the materials properties.In sintered AlN material, several different planar defects have previously been examined. Anti-phase boundaries (which produce the same configuration as basal twins in this structure) and stacking-faults have been identified in this material. A defect described as a “dome-like defect” has also been reported. The association of oxygen impurities with these extended defects has also been proposed. In this paper we report the observation of a defect (which may be the same as the “dome-like defect”) consisting of a flat, planar, basal fault and a curved, planar fault (rather than a spherical one) which join together to enclose a region of AlN, and separate it from the rest of the grain.
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Niang, Aliou, Julitte Huez, Jacques Lacaze i Bernard Viguier. "Characterizing Precipitation Defects in Nickel Based 718 Alloy". Materials Science Forum 636-637 (styczeń 2010): 517–22. http://dx.doi.org/10.4028/www.scientific.net/msf.636-637.517.
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In the present study we examine the crystallographic structure of the , ’’ and phases present in nickel base 718 alloy. The chemical ordering of Nb atoms and possible planar faults that may be observed in ’’ precipitates are detailed. High resolution transmission electron microscopy (HRTEM) observations of various faults are reported. The decomposition of a matrix dislocation to form a locked V shaped configuration is shown. The observation along [110] type direction allows to identify the type of defect, which is observed as a pure geometric stacking fault.
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Kurz, S. J. B., A. Leineweber i E. J. Mittemeijer. "Interpretation of electron diffraction patterns in the presence of oriented planar faults". Journal of Applied Crystallography 48, nr 6 (28.11.2015): 1921–26. http://dx.doi.org/10.1107/s1600576715018919.
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The presence of high planar-fault densities in thin films,e.g.nanotwinned films, leads to peculiar diffraction effects. Frequently, the planar faults are oriented perpendicular to the growth direction. For the case of (nanosized) thin films of face-centered cubic (fcc) metals, often a {111}fccfiber texture prevails with the fiber axis parallel to the film normal. In diffraction patterns of cross-sectional transmission electron microscopy (TEM) samples of such films, as a consequence of twinning with (111) planes parallel to the surface as twinning planes, intensity streaks appear parallel to the growth direction. These intensity streaks are, however, invisible in diffraction patterns of top-view TEM samples. The latter diffraction patterns might be interpreted, at first sight, in terms of the diffraction pattern of a somehow textured fcc polycrystal. However, the diffraction-ring radii deviate from the expected radii. The consideration of intensity cylinders in reciprocal space formed by diffuse intensity streaks generated by the planar faults leads to a perfect match of the accordingly predicted radii with the observed intensity-ring radii.
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Šturm, Sašo, Makoto Shiojiri i Miran Čeh. "Atomic-scale structural and compositional analyses of Ruddlesden-Popper planar faults in AO-excess SrTiO3 (A = Sr2+, Ca2+, Ba2+) ceramics". Journal of Materials Research 24, nr 8 (sierpień 2009): 2596–604. http://dx.doi.org/10.1557/jmr.2009.0321.
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The microstructure in AO-excess SrTiO3 (A = Sr2+, Ca2+, Ba2+) ceramics is strongly affected by the formation of Ruddlesden-Popper fault–rich (RP fault) lamellae, which are coherently intergrown with the matrix of the perovskite grains. We studied the structure and chemistry of RP faults by applying quantitative high-resolution transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy analyses. We showed that the Sr2+ and Ca2+ dopant ions form RP faults during the initial stage of sintering. The final microstructure showed preferentially grown RP fault lamellae embedded in the central part of the anisotropic perovskite grains. In contrast, the dopant Ba2+ ions preferably substituted for Sr2+ in the SrTiO3 matrix by forming a BaxSr1−xTiO3 solid solution. The surplus of Sr2+ ions was compensated structurally in the later stages of sintering by the formation of SrO-rich RP faults. The resulting microstructure showed RP fault lamellae located at the surface of equiaxed BaxSr1-xTiO3 perovskite grains.
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Suzuki, Mayumi, i Kouichi Maruyama. "Effects of Stacking Faults on High Temperature Creep Behavior in Mg-Y-Zn Based Alloys". Materials Science Forum 638-642 (styczeń 2010): 1602–7. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.1602.
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Compressive creep behavior of hot-rolled (40%) Mg-Y and Mg-Y-Zn alloys are investigated at 480 ~ 650 K. Creep strength is substantially improved by the simultaneous addition of yttrium and zinc. The minimum creep rate of Mg-0.9mol%Y-0.04mol%Zn (WZ301) alloy decreases to 1/10 lower than that of Mg-1.1mol%Y (W4) alloy at 650 K. Activation energy for creep in W4 and WZ301 alloys are more than 200 kJ/mol at the temperature range of 480 ~ 550 K. These values are higher than the activation energy for self-diffusion coefficient in magnesium (135 kJ/mol). Many stacking faults (planar defects, PDs) are only observed on the basal planes of the matrix in Mg-Y-Zn ternary alloys. Stacking fault energy is considered to decrease by the multiple-addition of yttrium and zinc. The size and density of these planar defects depend on solute content, aging condition. TEM observation has been revealed that the decreasing of the stacking fault energy affects the distribution of dislocations during creep. Many a-dislocations on basal planes are extended significantly. Dislocation motion is restricted significantly by both of these two types of stacking faults (planar type and extended dislocations).
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Deng, Hongdan, i Ken McClay. "Three-dimensional geometry and growth of a basement-involved fault network developed during multiphase extension, Enderby Terrace, North West Shelf of Australia". GSA Bulletin 133, nr 9-10 (28.01.2021): 2051–78. http://dx.doi.org/10.1130/b35779.1.
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Abstract Basement fault reactivation, and the growth, interaction, and linkage with new fault segments are fundamentally three-dimensional and critical for understanding the evolution of fault network development in sedimentary basins. This paper analyzes the evolution of a complex, basement-involved extensional fault network on the Enderby Terrace on the eastern margin of the Dampier sub-basin, North West Shelf of Australia. A high-resolution, depth-converted, 3-D seismic reflection data volume is used to show that multiphase, oblique extensional reactivation of basement-involved faults controlled the development of the fault network in the overlying strata. Reactivation of the pre-existing faults initially led to the formation of overlying, en échelon Late Triassic–Middle Jurassic fault segments that, as WNW-directed rifting progressed on the margin, linked by breaching of relay zones to form two intersecting fault systems (F1 and F2–F4). Further reactivation in the latest Jurassic–Early Cretaceous (NNW-SSE extension) produced an additional set of en échelon fault arrays in the cover strata. The final fault network consists of main or principal faults and subordinate or splay faults, together with branch lines that link the various components. Our study shows that breaching of relay ramps and/or vertical linkages produces vertical and horizontal branch lines giving complex final fault geometries. We find that repeated activity of the basement-involved faults tends to form continuous and planar fault architectures that favor displacement transfer between the main constituent segments along strike and with depth.
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Boulle, A., C. Legrand, R. Guinebretière, J. P. Mercurio i A. Dauger. "Planar faults in layered Bi-containing perovskites studied by X-ray diffraction line profile analysis". Journal of Applied Crystallography 34, nr 6 (17.11.2001): 699–703. http://dx.doi.org/10.1107/s0021889801011700.
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Profile fitting procedures associated with integral breadth studies and Fourier analysis are applied to the study of the complex Bi-containing layered perovskite SrBi2Nb2O9. Strong line broadening anisotropy is evidenced. Both `size' and `strain' effects contribute to the observed width. However, `size' broadening along the [00l] direction is essentially caused by stacking faults. The coherently diffracting domain sizes are deduced from Fourier analysis of the diffraction patterns and a rough estimate of the mean distance between faults is given. Thermal annealing significantly decreases the stacking fault density.
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Tilley, R. J. D., i R. P. Williams. "Structures containing shift-lattice distributed planar faults". Acta Crystallographica Section B Structural Science 51, nr 5 (1.10.1995): 758–67. http://dx.doi.org/10.1107/s0108768195004381.
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Murphy, S., i A. Herrero. "Surface rupture in stochastic slip models". Geophysical Journal International 221, nr 2 (3.02.2020): 1081–89. http://dx.doi.org/10.1093/gji/ggaa055.
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SUMMARY As an alternative to spectral methods, stochastic self-similar slip can be produced through a composite source model by placing a power-law scaling size-frequency distribution of circular slip dislocations on a fault surface. However these models do not accurately account for observed surface rupture behaviour. We propose a modification to the composite source model that corrects this issue. The advantage of this technique is that it accommodates the use of fractal slip distributions on non-planar fault surfaces. However to mimic a surface rupture using this technique, releasing the boundary condition at the top of the fault, we observed a systematic decrease in slip at shallow depths. We propose a new strategy whereby the surface is treated like a reflector with the slip being folded back onto the fault. Two different techniques based on this principal are presented: the first is the method of images. It requires a small change to pre-existing codes and works for planar faults. The second involves the use of a multistage trilateration technique. It is applied to non-planar faults described by an unstructured mesh. The reflected slip calculated using the two techniques is near identical on a planar fault, suggesting they are equivalent. Applying this correction, where reflected slip is accounted for in the composite source model, the lack of slip at shallow depths is not observed any more and there is no systematic trend with depth. However, there are other parameters which may affect the spatial distribution of slip across the fault plane. For example, the type of probability density function used in the placement of the subevent is also important. In the case where the location of maximum slip is known to a first order, a Gaussian may be appropriate to describe the probability function. For hazard assessment studies a uniform probability density function is more suitable as it provides no underlying systematic spatial trend.
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Lorentzen, Mads C., Kenneth Bredesen, Florian, W. ,. H. Smit, Torsten H. Hansen, Lars Nielsen i Klaus Mosegaard. "Mapping Cretaceous faults using a convolutional neural network – A field example from the Danish North Sea". Bulletin of the Geological Society of Denmark 71 (15.08.2022): 31–50. http://dx.doi.org/10.37570/bgsd-2022-71-03.
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The mapping of faults provides essential information on many aspects of seismic exploration, characterisation of reservoirs for compartmentalisation and cap-rock integrity. However, manual interpretation of faults from seismic data is time-consuming and challenging due to limited resolution and seismic noise. In this study, we apply a convolutional neural network trained on synthetic seismic data with planar fault shapes to improve fault mapping in the Lower and Upper Cretaceous sections of the Valdemar Field in the Danish North Sea. Our objective is to evaluate the performance of the neural network model on post-stack seismic data from the Valdemar Field. Comparison with variance and ant-tracking attributes and a manual fault interpretation shows that the neural network predicts faults with more details that may improve the overall geological and tectonic understanding of the study area and add information on potential compartmentalisation that was previously overlooked. However, the neural network is sensitive to seismic noise, which can distort the fault predictions. Therefore, the proposed model should be treated as an additional fault interpretation tool. Nonetheless, the method represents a state-of-the-art fault mapping tool that can be useful for hydrocarbon exploration and CO2 storage site evaluations.
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Eggeler, Y. M., K. V. Vamsi i T. M. Pollock. "Precipitate Shearing, Fault Energies, and Solute Segregation to Planar Faults in Ni-, CoNi-, and Co-Base Superalloys". Annual Review of Materials Research 51, nr 1 (26.07.2021): 209–40. http://dx.doi.org/10.1146/annurev-matsci-102419-011433.
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The mechanical properties of superalloys are strongly governed by the resistance to shearing of ordered precipitates by dislocations. In the operating environments of superalloys, the stresses and temperatures present during thermomechanical loading influence the dislocation shearing dynamics, which involve diffusion and segregation processes that result in a diverse array of planar defects in the ordered L12 γ′ precipitate phase. This review discusses the current understanding of high-temperature deformation mechanisms of γ′ precipitates in two-phase Ni-, Co-, and CoNi-base superalloys. The sensitivity of planar fault energies to chemical composition results in a variety of unique deformation mechanisms, and methods to determine fault energies are therefore reviewed. The degree of chemical segregation in the vicinity of planar defects reveals an apparent phase transformation within the parent γ′ phase. The kinetics of segregation to linear and planar defects play a significant role in high-temperature properties. Understanding and controlling fault energies and the associated dislocation dynamics provide a new pathway for the design of superalloys with exceptional properties.
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Zhang, Guowei, i Andrew Hynes. "Fabrics and kinematic indicators associated with the local structures along Finlay – Ingenika fault, McConnell Creek area, north-central British Columbia". Canadian Journal of Earth Sciences 31, nr 11 (1.11.1994): 1687–99. http://dx.doi.org/10.1139/e94-151.
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Structures associated with dextral transcurrent displacement on the Finlay – Ingenika fault are characterized predominantly by subvertical to vertical faults. Intersections of the fault planes with planar fabrics are all subvertical. This geometry, together with the common occurrence of subhorizontal slickenlines and stretching lineations in some strongly deformed fault zones, indicates their strike-slip nature. Principal directions of the strain ellipsoids determined from the deformed volcanic fragments along one of the faults are in accordance with those of the magnetic susceptibility ellipsoids from the adjacent plutonic rocks, indicating that the plutonic rocks experienced the same deformation as the Late Triassic Takla Group volcanics. Regional cleavage within the fault-bounded blocks indicates that the blocks were nonuniformly rotated clockwise about subvertical axes in response to progressive dextral transcurrent displacement on the Finlay – Ingenika fault. The mode of deformation observed in the area may characterize many parts of the Intermontane Belt.
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Papatheodorou, Sotiris, i Anthony Tzes. "Fault tolerant area coverage control for multiagent systems". MATEC Web of Conferences 188 (2018): 05010. http://dx.doi.org/10.1051/matecconf/201818805010.
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The fault tolerance characteristics of a distributed multi-agent coverage algorithm are examined. A team of sensor-equipped mobile agents is tasked with covering a planar region of interest. A distributed, gradient-based control scheme is utilized for this purpose. The agents are assumed to consist of three subsystems, each one of which may fail. The subsystems under examination are the actuation, sensing and the communication subsystem. Partial and catastrophic faults are examined. Several simulation studies are conducted highlighting the robustness of the distributed nature of the control scheme to these classes of faults, even when several of them happen at the same time.
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Koehl, Jean-Baptiste P., Gard Christophersen, Maxime Collombin, Christoffer Taule, Eirik M. B. Stokmo i Lis Allaart. "Devonian-Mississippian faulting controlled by WNW-ESE-striking structural grain in Proterozoic basement rocks in Billefjorden, central Spitsbergen". Geologica Acta 21 (28.07.2023): 1–16. http://dx.doi.org/10.1344/geologicaacta2023.21.7.
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In Billefjorden, central Spitsbergen, Devonian collapse and Carboniferous rift-related sedimentary strata were deposited unconformably over Proterozoic basement rocks displaying well developed N-S-trending Caledonian grain. Caledonian structures and fabrics are thought to have controlled the location and trend of subsequent Devonian and Carboniferous basin-bounding faults like the Billefjorden fault zone and Lemströmfjellet–Løvehovden fault. However, fieldwork and interpretation of aerial photographs in Proterozoic basement rocks reveal the existence of steep, abundant, WNW-ESE-striking brittle faults that are sub-orthogonal to known major Caledonian and post-Caledonian structures in Billefjorden, but that do not extend into adjacent-overlying, rift-related, Pennsylvanian rocks of the Gipsdalen Group. Structural analysis of field data and aerial photographs suggest that WNW-ESE-striking faults in basement rocks in Billefjorden formed as (sinistral) strike-slip and normal faults during Devonian-Mississippian extension in agreement with previously inferred models of sinistral transtension. The abundance of these faults suggest that their formation was controlled by analogously trending, preexisting structural grain (planar anisotropies) at depth, and their pronounced WNW-ESE strike suggest that the strike of preexisting anisotropies were comparable to recently identified, crustal-scale, WNW-ESE-striking Timanian thrust systems in Svalbard and the northern Barents Sea.
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Pérez, R., i M. Avalos-Borja. "Planar Defects in Small Particles". Proceedings, annual meeting, Electron Microscopy Society of America 43 (sierpień 1985): 392–93. http://dx.doi.org/10.1017/s0424820100118837.
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Transmission electron microscope techniques have been extensively used in the determination of the morphology of fine metallic particles. These techniques have been of particular importance in obtaining topographical information during particle growth and sintering. Thus, for example, it has been found that some of the most elementary forms consist of half cubo-octahedral units with (111) faces and (100) basis. Furthermore, full cubo-octahedral units have also been found, some of them showing stacking faults (SF) through the particles.It is important to point out that the characterization of this type of planar defects in small metallic particles has commonly been based on geometrical con. siderations. Additionally, the imaging conditions which have been used are the so-called weak beam (WB) diffraction conditions. Recent investigations have shown, on the other hand, that SF images under WB conditions present serious inconveniences, for example, contrast asymmetries in SF images which are not totally explained. Another difficulty with these WB fault images arises from twin boundaries which display image contrast similar to SF when a common reflection is strongly excited.
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Galindo, Pedro A., i Lidia Lonergan. "Sigmoidal normal faults and evidence for vertical-axis block rotation in an oblique convergent margin: A 3D seismic example from offshore Colombia". Leading Edge 40, nr 12 (grudzień 2021): 923–30. http://dx.doi.org/10.1190/tle40120923.1.
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Sigmoidal fold and fault geometries are typical kinematic indicators of strike-slip fault zones. We document kilometer-scale, normal faults with sigmoidal plan-view geometries within the dextral pull-apart Bahia Basin, at the rear of the obliquely convergent South Caribbean Deformed Belt, offshore Colombia. Using 3D seismic reflection data calibrated to wells, closely spaced, low-displacement, planar normal faults are mapped within the Miocene strata. A series of seismic horizontal (time) slices and computed seismic attributes are used to interpret the 3D configuration of these faults. The closely spaced faults display an east–west trend with a progressive rotation into a northwest–southeast trend. In map view, the fault traces curve toward their tips, describing a sigmoidal-Z geometry that terminates at discrete northeast–southwest-trending fault zones. The structures observed may correspond to either tension fractures, which form theoretically at 45°, or antithetic shear fractures with normal displacement formed at 50°–70° to the boundaries of a dextral shear zone. These scenarios lead to a clockwise block rotation of between 20° and 40° within the shear zone. This study shows the first example of vertical-axis block rotations observed offshore in the western end of the South Caribbean margin and is an important example of the use of 3D seismic data to identify rotations where paleomagnetic studies are not available.
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Lu, Weifan, Yijian Zhou, Zeyan Zhao, Han Yue i Shiyong Zhou. "Aftershock sequence of the 2017 Mw 6.5 Jiuzhaigou, China earthquake monitored by an AsA network and its implication to fault structures and strength". Geophysical Journal International 228, nr 3 (29.10.2021): 1763–79. http://dx.doi.org/10.1093/gji/ggab443.
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SUMMARY We deployed a seismic network near the source region of the 2017 Mw 6.5 Jiuzhaigou earthquake to monitor aftershock activity and to investigate the local fault structure. An aftershock deployment of Array of small Arrays (AsA) and a Geometric Mean Envelop (GME) algorithm are adopted to enhance detection performance. We also adopt a set of association, relocation and matched-filter techniques to obtain a detailed regional catalogue. 16 742 events are detected and relocated, including 1279 aftershocks following the Mw 4.8 aftershock. We develop a joint inversion algorithm utilizing locations of event clusters and focal mechanisms to determine the geometry of planar faults. Six segments were finally determined, in which three segments are related to the Huya fault reflecting a change in fault dip direction near the main shock hypocentre, while the other segments reflect branches showing orthogonal and conjugate geometries with the Huya fault. Aftershocks were active on branching faults between the Huya and Minjiang faults indicating that the main shock may have ruptured both major faults. We also resolve a fault portion with ‘weak strength’ near the main shock hypocentre, which is characterized by limited coseismic slips, concentrated afterslip, low aftershock activities, high b-value and high sensitivity to stress changes. These phenomena can be explained by fault frictional properties at conditional stable sliding status, which may be related to the localized high pore-fluid pressure produced by the fluid intrusion.
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Liu, M., Hans Jørgen Roven, Maxim Yu Murashkin i Ruslan Valiev. "Deformation Twins and Stacking Faults in an AA5182 Al-Mg Alloy Processed by High Pressure Torsion". Materials Science Forum 579 (kwiecień 2008): 147–54. http://dx.doi.org/10.4028/www.scientific.net/msf.579.147.
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High-resolution transmission electron microscopy investigations revealed different types of deformation structures in a nanostructured commercial Al–Mg alloy processed by high pressure torsion at room temperature. Microtwins and stacking faults were detected within both nanocrystalline grains and ultrafine grains. Full dislocations in the form of dipoles were observed within grains and near the grain boundaries. Two twinning mechanisms previously predicted by molecular-dynamics simulations were directly verified including the heterogeneous twins nucleated by the successive emission of Shockley partials from grain boundaries and homogeneous twins formed in the grain interiors by the dynamic overlapping of stacking faults. Hence, the formation of full dislocations, stacking faults and twins in the present aluminum alloy subjected to severe plastic deformation may be interpreted in terms of molecular-dynamics simulations based on generalized planar fault energy curves for pure metal systems.
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Schneeberger, Raphael, Miguel de La Varga, Daniel Egli, Alfons Berger, Florian Kober, Florian Wellmann i Marco Herwegh. "Methods and uncertainty estimations of 3-D structural modelling in crystalline rocks: a case study". Solid Earth 8, nr 5 (28.09.2017): 987–1002. http://dx.doi.org/10.5194/se-8-987-2017.
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Abstract. Exhumed basement rocks are often dissected by faults, the latter controlling physical parameters such as rock strength, porosity, or permeability. Knowledge on the three-dimensional (3-D) geometry of the fault pattern and its continuation with depth is therefore of paramount importance for applied geology projects (e.g. tunnelling, nuclear waste disposal) in crystalline bedrock. The central Aar massif (Central Switzerland) serves as a study area where we investigate the 3-D geometry of the Alpine fault pattern by means of both surface (fieldwork and remote sensing) and underground ground (mapping of the Grimsel Test Site) information. The fault zone pattern consists of planar steep major faults (kilometre scale) interconnected with secondary relay faults (hectometre scale). Starting with surface data, we present a workflow for structural 3-D modelling of the primary faults based on a comparison of three extrapolation approaches based on (a) field data, (b) Delaunay triangulation, and (c) a best-fitting moment of inertia analysis. The quality of these surface-data-based 3-D models is then tested with respect to the fit of the predictions with the underground appearance of faults. All three extrapolation approaches result in a close fit ( > 10 %) when compared with underground rock laboratory mapping. Subsequently, we performed a statistical interpolation based on Bayesian inference in order to validate and further constrain the uncertainty of the extrapolation approaches. This comparison indicates that fieldwork at the surface is key for accurately constraining the geometry of the fault pattern and enabling a proper extrapolation of major faults towards depth. Considerable uncertainties, however, persist with respect to smaller-sized secondary structures because of their limited spatial extensions and unknown reoccurrence intervals.
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Mildon, Zoe K., Gerald P. Roberts, Joanna P. Faure Walker i Francesco Iezzi. "Coulomb stress transfer and fault interaction over millennia on non-planar active normal faults: the Mw 6.5–5.0 seismic sequence of 2016–2017, central Italy". Geophysical Journal International 210, nr 2 (30.05.2017): 1206–18. http://dx.doi.org/10.1093/gji/ggx213.
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Abstract In order to investigate the importance of including strike-variable geometry and the knowledge of historical and palaeoseismic earthquakes when modelling static Coulomb stress transfer and rupture propagation, we have examined the August–October 2016 A.D. and January 2017 A.D. central Apennines seismic sequence (Mw 6.0, 5.9, 6.5 in 2016 A.D. (INGV) and Mw 5.1, 5.5, 5.4, 5.0 in 2017 A.D. (INGV)). We model both the coseismic loading (from historical and palaeoseismic earthquakes) and interseismic loading (derived from Holocene fault slip-rates) using strike-variable fault geometries constrained by fieldwork. The inclusion of the elapsed times from available historical and palaeoseismological earthquakes and on faults enables us to calculate the stress on the faults prior to the beginning of the seismic sequence. We take account the 1316–4155 yr elapsed time on the Mt. Vettore fault (that ruptured during the 2016 A.D. seismic sequence) implied by palaeoseismology, and the 377 and 313 yr elapsed times on the neighbouring Laga and Norcia faults respectively, indicated by the historical record. The stress changes through time are summed to show the state of stress on the Mt. Vettore, Laga and surrounding faults prior to and during the 2016–2017 A.D. sequence. We show that the build up of stress prior to 2016 A.D. on strike-variable fault geometries generated stress heterogeneities that correlate with the limits of the main-shock ruptures. Hence, we suggest that stress barriers appear to have control on the propagation and therefore the magnitudes of the main-shock ruptures.
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Arnoth, F. W., M. Wade i G. P. Mohanty. "Diffraction from planar faults in the halite structure". Journal of Physics: Condensed Matter 2, nr 38 (24.09.1990): 7725–32. http://dx.doi.org/10.1088/0953-8984/2/38/001.
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Hale, Dave, i Richard H. Groshong. "Conical faults apparent in a 3D seismic image". Interpretation 2, nr 1 (1.02.2014): T1—T11. http://dx.doi.org/10.1190/int-2013-0121.1.
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Map-scale geologic faults with a conical shape are apparent in a public-domain 3D seismic image of block F3 in the Dutch sector of the North Sea. These cone-shaped normal faults exist among many polygonal normal faults in fine-grained clay sediments. The conical faults were discovered using new algorithms for seismic image processing, but they are apparent without that processing. They appear circular in horizontal image slices and have an inverted-V shape in vertical sections for any azimuth through their vertical axes of symmetry. They form horsts bounded by planar strata above and below, with maximum throws of about 35 m roughly halfway between their bases and tops. The bases are up to 1 km wide, and dips of the conical faults are in the range 35º–38º. Because polygonal faults exist elsewhere at or near the seafloor with dips of about 60º, most such faults likely formed close to the depositional interface; the much lower dips of deeply buried faults, such as the faults observed here, are likely due to vertical compaction. We inferred that polygonal and conical fault geometries result from a uniform radial extension stress caused by volumetric contraction, analogous to the formation of mudcracks. Cone-shaped faults have been observed in laboratory experiments on rocks and ceramics, where the conical geometry results from uniaxial compression. In the subsurface, the formation of conical faults implies that stresses and sediments were exceptionally homogeneous. The cone shape suggests a pointlike heterogeneity near the depositional surface, which served as a trigger for downward propagation of the faults, rather unlike the random, in-plane propagation and linking inferred by others for polygonal faults.
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Alobaidy, Muhamad Azhar Abdilatef, Jassim Mohammed Abdul-Jabbar i Saad Zaghlul Al-khayyt. "Slantlet transform used for faults diagnosis in robot arm". Indonesian Journal of Electrical Engineering and Computer Science 25, nr 1 (1.01.2022): 281. http://dx.doi.org/10.11591/ijeecs.v25.i1.pp281-290.
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<p class="JESTECAbstract">The <span>robot arm systems are the most target systems in the fields of faults detection and diagnosis which are electrical and the mechanical systems in many fields. Fault detection and diagnosis study is presented for two robot arms. The disturbance due to the faults at robot's joints causes oscillations at the tip of the robot arm. The acceleration in multi-direction is analysed to extract the features of the faults. Simulations for planar and space robots are presented. Two types of feature (faults) detection methods are used in this paper. The first one is the discrete wavelet transform, which is applied in many research's works before. The second type, is the Slantlet transform, which represents an improved model of the discrete wavelet transform. The multi-layer perceptron artificial neural network is used for the purpose of faults allocation and classification. According to the obtained results, the Slantlet transform with the multi-layer perceptron artificial neural network appear to possess best performance (4.7088e-05), lower consuming time <br /> (71.017308 sec) and higher accuracy (100%) than the results obtained when applying discrete wavelet transform and artificial neural network for the same </span>purpose.</p>
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Delogkos, Efstratios, Muhammad Mudasar Saqab, John J. Walsh, Vincent Roche i Conrad Childs. "Throw variations and strain partitioning associated with fault-bend folding along normal faults". Solid Earth 11, nr 3 (28.05.2020): 935–45. http://dx.doi.org/10.5194/se-11-935-2020.
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Abstract. Normal faults have irregular geometries on a range of scales arising from different processes including refraction and segmentation. A fault with constant dip and displacement on a large-scale will have irregular geometries on smaller scales, the presence of which will generate fault-related folds and down-fault variations in throw. A quantitative model is presented which illustrates the deformation arising from movement on irregular fault surfaces, with fault-bend folding generating geometries reminiscent of normal and reverse drag. Calculations based on the model highlight how fault throws are partitioned between continuous (i.e. folding) and discontinuous (i.e. discrete offset) strain along fault bends for the full range of possible fault dip changes. These calculations illustrate the potential significance of strain partitioning on measured fault throw and the potential errors that will arise if account is not taken of the continuous strains accommodated by folding and bed rotations. We show that fault throw can be subject to errors of up to ca. 50 % for realistic down-dip fault bend geometries (up to ca. 40∘), on otherwise sub-planar faults with constant displacement. This effect will provide irregular variations in throw and bed geometries that must be accounted for in associated kinematic interpretations.
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Powell, W. G., i C. J. Hodgson. "Deformation of the Gowganda Formation, Matachewan area, Ontario, by post-Early Proterozoic reactivation of the Archean Larder Lake – Cadillac break, with implications for gold exploration". Canadian Journal of Earth Sciences 29, nr 7 (1.07.1992): 1580–89. http://dx.doi.org/10.1139/e92-124.
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Segments of the Larder Lake – Cadillac break (LLCB), an east–west-trending Archean shear zone in the southern Abitibi greenstone belt, are covered by Early Proterozoic sedimentary rocks of the Gowganda Formation. These rocks severely hamper exploration for Archean gold deposits associated with the LLCB. Along the parts of the LLCB covered by Gowganda Formation in the Matachewan area, Ontario, synsedimentary structures localized along the paleotopographic lineament of the LLCB and deformation structures due to post-Gowganda reactivation of the LLCB and related splay faults can be used to locate underlying Archean faults. Deformation structures in the Gowganda Formation are localized where the northeast–southwest-trending LLCB and associated splay faults are intersected by north–south-trending Archean faults. These Proterozoic structures comprise an array of right-stepping, en echelon folds with variably developed axial-planar cleavage, aligned along the trend of the northeast–southwest-trending basement faults, and linear zones of folds with associated axial-planar cleavage aligned along the trend of north–south-trending basement faults. Kinematic analysis of the structures in the Gowganda Formation indicates dominantly dextral strike-slip reactivation of northeast–southwest-trending faults, and dominantly reverse reactivation of north–south-trending faults. Reactivation of Archean faults may have occurred during the tectonic event that produced the Kapuskasing structure, and (or) during the Grenville orogeny. Past geochemical surveys conducted in one of these deformation zones within the Gowganda Formation in western Quebec indicate that Au can be remobilized from the Archean basement into the deformed Proterozoic rocks. Thus it is possible to delineate the Archean shear zones and test for the presence of associated gold mineralization in areas where the Archean faults are overlain by the Gowganda Formation.
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Cruz-Atienza, Víctor M., Jean Virieux i Hideo Aochi. "3D finite-difference dynamic-rupture modeling along nonplanar faults". GEOPHYSICS 72, nr 5 (wrzesień 2007): SM123—SM137. http://dx.doi.org/10.1190/1.2766756.
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Proper understanding of seismic emissions associated with the growth of complexly shaped microearthquake networks and larger-scale nonplanar fault ruptures, both in arbitrarily heterogeneous media, requires accurate modeling of the underlying dynamic processes. We present a new 3D dynamic-rupture, finite-difference model called the finite-difference, fault-element (FDFE) method; it simulates the dynamic rupture of nonplanar faults subjected to regional loads in complex media. FDFE is based on a 3D methodology for applying dynamic-rupture boundary conditions along the fault surface. The fault is discretized by a set of parallelepiped fault elements in which specific boundary conditions are applied. These conditions are applied to the stress tensor, once transformed into a local fault referenceframe. Numerically determined weight functions multiplying particle velocities around each element allow accurate estimates of fault kinematic parameters (i.e., slip and slip rate) independent of faulting mechanism. Assuming a Coulomb-like slip-weakening friction law, a parametric study suggests that the FDFE method converges toward a unique solution, provided that the cohesive zone behind the rupture front is well resolved (i.e., four or more elements inside this zone). Solutions are free of relevant numerical artifacts for grid sizes smaller than approximately [Formula: see text]. Results yielded by the FDFE approach are in good quantitative agreement with those obtained by a semianalytical boundary integral method along planar and nonplanar parabola-shaped faults. The FDFE method thus provides quantitative, accurate results for spontaneous-rupture simulations on intricate fault geometries.
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Rodriguez-Alfaro, Luis H., Efrain Alcorta-Garcia, David Lara i Gerardo Romero. "A Hamiltonian Approach to Fault Isolation in a Planar Vertical Take–Off and Landing Aircraft Model". International Journal of Applied Mathematics and Computer Science 25, nr 1 (1.03.2015): 65–76. http://dx.doi.org/10.1515/amcs-2015-0005.
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Abstract The problem of fault detection and isolation in a class of nonlinear systems having a Hamiltonian representation is considered. In particular, a model of a planar vertical take-off and landing aircraft with sensor and actuator faults is studied. A Hamiltonian representation is derived from an Euler-Lagrange representation of the system model considered. In this form, nonlinear decoupling is applied in order to obtain subsystems with (as much as possible) specific fault sensitivity properties. The resulting decoupled subsystem is represented as a Hamiltonian system and observer-based residual generators are designed. The results are presented through simulations to show the effectiveness of the proposed approach.
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Tanner, David C., Patrick Musmann, Britta Wawerzinek, Hermann Buness, Charlotte M. Krawczyk i Rüdiger Thomas. "Salt tectonics of the eastern border of the Leinetal Graben, Lower Saxony, Germany, as deduced from seismic reflection data". Interpretation 3, nr 3 (1.08.2015): T169—T181. http://dx.doi.org/10.1190/int-2014-0221.1.
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To study the salt-related tectonic evolution of the Leinetal Graben, located in the southernmost part of the Central European Basin (CEB) in Germany, we acquired two (1.8- and 3.2-km-long) P-wave reflection seismic profiles across the eastern border faults of the graben. The profiles were acquired with a minivibro along a 1.8-km active spread, densely sampled by geophones spaced at 5 m. The resulting sections showed stratigraphic and fault geometries to a depth of approximately 1200 m. Using two deep boreholes for calibration, we interpreted Mesozoic strata down to the Triassic Zechstein salt and the faults that affected these strata. We recognized two sets of faults: (1) steep, planar faults that are closely clustered and terminated in the Zechstein salt (type 1) and (2) shallow faults that connected between the first set of faults and have very variable dip, depending on the lithology they intersect (type 2). We discovered that the faults do not cross cut the Zechstein salt, but instead they decoupled at this layer. The present-day structure can be interpreted using a two-stage tectonic model. Either there was “downbuilding” during the Triassic, “rafting” of lower Buntsandstein blocks on the Zechstein salt, or both. This resulted in a proto-Leinetal Graben Zechstein diapir surrounded by depocenters. During the Late Cretaceous/Early Tertiary inversion phase, the diapir collapsed, first along type 1 steep faults that detached in the salt layer, and later along type 2 faults; the latter formed as the result of continued extension. Recognition of such early halokinesis was important for the understanding of the behavior of the salt in the CEB and salt tectonics in general.
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Yan, Sujie, Xinghai Zhou, Renhai Pu i Changyu Fan. "Controls of the Sandbody Scale and Fault Throw on the Lithology and Composite Reservoir Formation in the Baoyunting Slope, East China Sea". Energies 16, nr 17 (26.08.2023): 6212. http://dx.doi.org/10.3390/en16176212.
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Under the conditions of many faults, sandbodies, and hydrocarbon sources on the slopes of faulted basins where structural traps are scarce, only a few sandbodies are capable of forming hydrocarbon pools, while most sandbodies act as aquifers. This situation presents a challenge for predicting favorable hydrocarbon accumulation areas and understanding controlling factors. The Pinghu Formation reservoirs in the Baoyunting nose structure of the Xihu Sag in the East China Sea exemplify this characteristic. Among the 19 small-scale oil and gas reservoirs discovered in this area, 10 are faulted sandbody composite traps and 9 are lithological traps, while the majority of the remaining sand layers, especially the thick layers, act as aquifers, resulting in significantly lower accumulation probabilities compared to the adjacent northern and southern areas. We analyzed the relationship between the sandstone thickness and the amplitude through the 1-D forward modeling of wells and dissected the 3-D seismic event to obtain the planar distribution of a single sandbody. Further comprehensive research on fault sealing and kinetic reservoir formation processes suggests that the gas pool formation in this area is closely related to fault sealing and lateral oil and gas transport. A small fault-to-caprock ratio is beneficial for the sealing of mudstone caprocks, while a large fault-to-sand thickness ratio is beneficial for the lateral sealing of faults and the formation of fault–sand composite pools. The tidal microfacies sandbody has a small scale, poor lateral transport ability, and a low probability of gas reservoir formation. The barrier and delta front sandbodies have a large scale, good lateral transport, and a high probability of reservoir formation. Based on the above methods, favorable pool formation traps were identified in the area, and high-yield gas wells were drilled.
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Bardal, A., O. Eibl, Th Matthée, G. Friedl i J. Wecker. "High-resolution electron microscopy of epitaxial YBCO/Y2O3/YSZ on Si(001)". Journal of Materials Research 8, nr 9 (wrzesień 1993): 2112–27. http://dx.doi.org/10.1557/jmr.1993.2112.
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The microstructures of YBa2Cu3O7−δ (YBCO) thin films grown on Si with Y-stabilized ZrO2 (YSZ) and Y2O3 buffer layers were characterized by means of high-resolution electron microscopy. At the Si–YSZ interface, a 2.5 nm thick layer of regrown amorphous SiOx is present. The layer is interrupted by crystalline regions, typically 5 to 10 nm wide and 10 to 50 nm apart. Close to the crystalline regions, {111} defects are present in the Si substrate. The typical defect observed is an extrinsic stacking fault plus a perfect dislocation close to the stacking fault which terminates extra {111} planes in the upper part of the Si. These defects are probably formed by condensation of Si self-interstitials created during oxide regrowth. Precipitates are present in the Si close to the Si–YSZ interface and indicate that in-diffusion of Zr has occurred. The YSZ–Y2O3 interface is atomically sharp and essentially planar and contains no second phases. Perfect misfit dislocations with Burgers vector 1/2〈110〉 are present at this interface along with unrelaxed elastic misfit stresses. The Y2O3–YBCO interface is atomically sharp and planar, but contains steps. (001) stacking faults are present in the YBCO above these steps; the faults are, however, healed a few unit cells away from the interface. By HREM analysis of ultrathin specimen areas, the atomic layer of the YBCO closest to the Y2O3 was found to be a barium-oxygen layer.
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Xu, Menglong, Yabin Yang, Chengye Sun, Gengen Qiu, Liang Chen i Lei Jing. "Geophysical Characterisation and Oil–Gas Resource Analysis of the Southern Huaying Mountain Fault Zone, Sichuan Basin, China". Minerals 13, nr 2 (14.02.2023): 270. http://dx.doi.org/10.3390/min13020270.
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As the west rim of an ejective fold zone, the Huaying Mountain fault zone (HMFZ) in the eastern Sichuan Basin (SB) plays an important role in the tectonic evolution of the SB. The distribution and characteristics of HMFZ are strongly associated with tectonic activities and have greatly impacted the distribution of oil and gas reservoirs. However, its distribution and characteristics have remained poorly understood due to a lack of geophysical data, especially areal gravity survey and magnetotellurics (MT) survey, which are admittedly advantageous for detecting the edges of geological structures. Therefore, we carried out the ground geophysical surveys that areal gravity survey and MT survey, and acquired 1:250,000-scale real gravity data and MT data for the first time in this area. Optimized edge-detection methods were adopted to process the areal gravity data, allowing us to characterize the planar distribution of faults more reliably and convincingly. We found that the southern HMFZ is well developed and primarily trends in NNE and NE, whereas the subordinate faults trend in N-S and W-E. Vertical information for the faults extracted using the improved depth from the extreme points method revealed that the fault dominantly dipped to the SE, which was consistent with the results of MT inversion. Based on the spatial distribution of the faults, we further discussed the gravity anomaly, fault distribution, Luzhou palaeo uplift, and the distribution and characteristics of oil-gas resources, and found the convincing evidence to analysis the distribution of oil and gas resources in this region.
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Abdi, Hamid, Saeid Nahavandi, Yakov Frayman i Anthony A. Maciejewski. "Optimal mapping of joint faults into healthy joint velocity space for fault-tolerant redundant manipulators". Robotica 30, nr 4 (8.08.2011): 635–48. http://dx.doi.org/10.1017/s0263574711000671.
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SUMMARYSelf-reconfiguration of robotic manipulators under joint failure can be achieved via fault-tolerance strategies. Fault-tolerant manipulators are required to continue their end-effector motion with a minimum velocity jump, when failures occur to their joints. Optimal fault tolerance of the manipulators requires a framework that can map the velocity jump of the end-effector to the compensating joint velocity commands. The main objective of the present paper is to propose a general framework for the fault tolerance of the manipulators, which can minimize the end-effector velocity jump. In the present paper, locked joint failures of the manipulators are modeled using matrix perturbation methodology. Then, the optimal mapping for the faults with a minimum end-effector velocity jump is presented. On the basis of this mapping, the minimum end-effector velocity jump is calculated. A generalized framework is derived from the extension of optimal mapping toward multiple locked joint failures. Two novel expressions are derived representing the generalized optimal mapping framework and the generalized minimum velocity jump. These expressions are suitable for the optimal fault tolerance of the serial link redundant manipulators. The required conditions for a zero end-effector velocity jump of the manipulators are analyzed. The generalized framework in this paper is then evaluated for different failure scenarios for a 5-DOF planar manipulator and a 5-DOF spatial manipulator. The validation includes three case studies. While the first two are instantaneous studies, the third one is for the whole trajectory of the manipulators. From the results of these case studies, it is shown that, when locked joint faults occur, the faulty manipulator is able to optimally maintain its velocity with a zero end-effector velocity jump if the conditions of a zero velocity jump are hold.
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Lisle, Richard J. "A critical look at the Wallace-Bott hypothesis in fault-slip analysis". Bulletin de la Société Géologique de France 184, nr 4-5 (1.07.2013): 299–306. http://dx.doi.org/10.2113/gssgfbull.184.4-5.299.
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AbstractThe assumption is widely made that slip on faults occurs in the direction of maximum resolved shear stress, an assumption known as the Wallace-Bott hypothesis. This assumption is used to theoretically predict slip directions from known in situ stresses, and also as the basis of palaeostress inversion from fault-slip data. This paper examines different situations in relation to the appropriateness of this assumption. Firstly, it is shown that the magnitude of the shear stress resolved within a plane is a function with a poorly defined maximum direction, so that shear stress values greater than 90% of the maximum occur within a wide angular range (± 26°) degrees. The situation of simultaneous movement on pairs of faults requires slip on each fault to be parallel to their mutual line of intersection. However, the resolved shear stresses arising from a homogeneous state of stress do not accord with such a slip arrangement except in the case of pairs of perpendicular faults. Where fault surfaces are non-planar, the directions of resolved shear stress in general give, according to the Wallace-Bott hypothesis, a set of slip directions of rigid fault blocks, which is generally kinematically incompatible. Finally, a simple model of a corrugated fault suggests that any anisotropy of the shear strength of the fault such as that arising from fault surface topography, can lead to a significant angular difference between the directions of maximum shear stress and the slip direction.These findings have relevance to the design of procedures used to estimate palaeostresses and the amount of data required for this type of analysis.
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Aghdaee, S. R., i V. Soleimanian. "Dislocations, crystallite size, and planar faults in nanocrystalline ceria". Powder Diffraction 24, nr 3 (wrzesień 2009): 228–33. http://dx.doi.org/10.1154/1.3187210.
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The modified Williamson–Hall and Warren–Averbach methods were used successfully for analyzing experimentally observed anisotropic X-ray diffraction line broadening and for determining reliable values of crystallite size and dislocation density in cerium oxide. The modified Williamson–Hall plot gives 22.3(2) nm for volume-weighted crystallite size, while the modified Warren–Averbach produces 18.0(2) nm for area-weighted grain size. The dislocation density and effective outer cut-off radius of dislocations obtained from the modified Warren–Averbach method are 1.8(3)×1015 m−2 and 15.5(1) nm, respectively.
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Viguier, Bernard, Mayerling Martinez i Jacques Lacaze. "Characterization of complex planar faults in FeAl(B) alloys". Intermetallics 83 (kwiecień 2017): 64–69. http://dx.doi.org/10.1016/j.intermet.2016.12.005.
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