Journal articles on the topic 'Continuum fault models'
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1
So, Byung-Dal, and Fabio A. Capitanio. "Self-consistent stick-slip recurrent behaviour of elastoplastic faults in intraplate environment: a Lagrangian solid mechanics approach." Geophysical Journal International 221, no. 1 (January 3, 2020): 151–62. http://dx.doi.org/10.1093/gji/ggz581.
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SUMMARY Our understanding of the seismicity of continental interiors, far from plate margins, relies on the ability to account for behaviours across a broad range of time and spatial scales. Deformation rates around seismic faults range from the slip-on-fault during earthquakes to the long-term viscous deformation of surrounding lithosphere, thereby presenting a challenge to modelling techniques. The aim of this study was to test a new method to simulate seismic faults using a continuum approach, reconciling the deformation of viscoelastoplastic lithospheres over geological timescales. A von Mises yield criterion is adopted as a proxy for the frictional shear strength of a fault. In the elastoplastic fault models a rapid change in strength occurs after plastic yielding, to achieve stress–strain equilibrium, when the coseismic slip and slip velocity from the strain-rate response and size of the fault are calculated. The cumulative step-function shape of the slip and temporally partitioned slip velocity of the fault demonstrated self-consistent discrete fault motion. The implementation of elastoplastic faults successfully reproduced the conceptual models of seismic recurrence, that is strictly periodic and time- and slip-predictable. Elastoplastic faults that include a slip velocity strengthening and weakening with reduction of the time-step size during the slip stage generated yield patterns of coseismic stress changes in surrounding areas, which were similar to those calculated from actual earthquakes. A test of fault interaction captured the migration of stress between two faults under different spatial arrangements, reproducing realistic behaviours across time and spatial scales of faults in continental interiors.
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Cheng, Feng, Andrew V. Zuza, Peter J. Haproff, Chen Wu, Christina Neudorf, Hong Chang, Xiangzhong Li, and Bing Li. "Accommodation of India–Asia convergence via strike-slip faulting and block rotation in the Qilian Shan fold–thrust belt, northern margin of the Tibetan Plateau." Journal of the Geological Society 178, no. 3 (January 29, 2021): jgs2020–207. http://dx.doi.org/10.1144/jgs2020-207.
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Existing models of intracontinental deformation have focused on plate-like rigid body motion v. viscous-flow-like distributed deformation. To elucidate how plate convergence is accommodated by intracontinental strike-slip faulting and block rotation within a fold–thrust belt, we examine the Cenozoic structural framework of the central Qilian Shan of northeastern Tibet, where the NW-striking, right-slip Elashan and Riyueshan faults terminate at the WNW-striking, left-slip Haiyuan and Kunlun faults. Field- and satellite-based observations of discrete right-slip fault segments, releasing bends, horsetail termination splays and off-fault normal faulting suggest that the right-slip faults accommodate block rotation and distributed west–east crustal stretching between the Haiyuan and Kunlun faults. Luminescence dating of offset terrace risers along the Riyueshan fault yields a Quaternary slip rate of c. 1.1 mm a−1, which is similar to previous estimates. By integrating our results with regional deformation constraints, we propose that the pattern of Cenozoic deformation in northeastern Tibet is compatible with west–east crustal stretching/lateral displacement, non-rigid off-fault deformation and broad clockwise rotation and bookshelf faulting, which together accommodate NE–SW India–Asia convergence. In this model, the faults represent strain localization that approximates continuum deformation during regional clockwise lithospheric flow against the rigid Eurasian continent.Supplementary material: Luminescence dating procedures and protocols is available at https://doi.org/10.17605/OSF.IO/CR9MNThematic collection: This article is part of the Fold-and-thrust belts and associated basins collection available at: https://www.lyellcollection.org/cc/fold-and-thrust-belts
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Mancini, Simone, Margarita Segou, Maximilian Jonas Werner, and Tom Parsons. "The Predictive Skills of Elastic Coulomb Rate-and-State Aftershock Forecasts during the 2019 Ridgecrest, California, Earthquake Sequence." Bulletin of the Seismological Society of America 110, no. 4 (June 23, 2020): 1736–51. http://dx.doi.org/10.1785/0120200028.
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ABSTRACT Operational earthquake forecasting protocols commonly use statistical models for their recognized ease of implementation and robustness in describing the short-term spatiotemporal patterns of triggered seismicity. However, recent advances on physics-based aftershock forecasting reveal comparable performance to the standard statistical counterparts with significantly improved predictive skills when fault and stress-field heterogeneities are considered. Here, we perform a pseudoprospective forecasting experiment during the first month of the 2019 Ridgecrest (California) earthquake sequence. We develop seven Coulomb rate-and-state models that couple static stress-change estimates with continuum mechanics expressed by the rate-and-state friction laws. Our model parameterization supports a gradually increasing complexity; we start from a preliminary model implementation with simplified slip distributions and spatially homogeneous receiver faults to reach an enhanced one featuring optimized fault constitutive parameters, finite-fault slip models, secondary triggering effects, and spatially heterogenous planes informed by pre-existing ruptures. The data-rich environment of southern California allows us to test whether incorporating data collected in near-real time during an unfolding earthquake sequence boosts our predictive power. We assess the absolute and relative performance of the forecasts by means of statistical tests used within the Collaboratory for the Study of Earthquake Predictability and compare their skills against a standard benchmark epidemic-type aftershock sequence (ETAS) model for the short (24 hr after the two Ridgecrest mainshocks) and intermediate terms (one month). Stress-based forecasts expect heightened rates along the whole near-fault region and increased expected seismicity rates in central Garlock fault. Our comparative model evaluation not only supports that faulting heterogeneities coupled with secondary triggering effects are the most critical success components behind physics-based forecasts, but also underlines the importance of model updates incorporating near-real-time available aftershock data reaching better performance than standard ETAS. We explore the physical basis behind our results by investigating the localized shut down of pre-existing normal faults in the Ridgecrest near-source area.
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Jung, Jai K., Thomas D. O’Rourke, and Christina Argyrou. "Multi-directional force–displacement response of underground pipe in sand." Canadian Geotechnical Journal 53, no. 11 (November 2016): 1763–81. http://dx.doi.org/10.1139/cgj-2016-0059.
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A methodology is presented to evaluate multi-directional force–displacement relationships for soil–pipeline interaction analysis and design. Large-scale tests of soil reaction to pipe lateral and uplift movement in dry and partially saturated sand are used to validate plane strain, finite element (FE) soil, and pipe continuum models. The FE models are then used to characterize force versus displacement performance for lateral, vertical upward, vertical downward, and oblique orientations of pipeline movement in soil. Using the force versus displacement relationships, the analytical results for pipeline response to strike-slip fault rupture are shown to compare favorably with the results of large-scale tests in which strike-slip fault movement was imposed on 250 and 400 mm diameter high-density polyethylene pipelines in partially saturated sand. Analytical results normalized with respect to maximum lateral force are provided on 360° plots to predict maximum pipe loads for any movement direction. The resulting methodology and dimensionless plots are applicable for underground pipelines and conduits at any depth, subjected to relative soil movement in any direction in dry or saturated and partially saturated medium to very dense sands.
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Armandine Les Landes, Antoine, Théophile Guillon, Mariane Peter-Borie, Arnold Blaisonneau, Xavier Rachez, and Sylvie Gentier. "Locating Geothermal Resources: Insights from 3D Stress and Flow Models at the Upper Rhine Graben Scale." Geofluids 2019 (May 12, 2019): 1–24. http://dx.doi.org/10.1155/2019/8494539.
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To be exploited, geothermal resources require heat, fluid, and permeability. These favourable geothermal conditions are strongly linked to the specific geodynamic context and the main physical transport processes, notably stresses and fluid circulations, which impact heat-driving processes. The physical conditions favouring the setup of geothermal resources can be searched for in predictive models, thus giving estimates on the so-called “favourable areas.” Numerical models could allow an integrated evaluation of the physical processes with adapted time and space scales and considering 3D effects. Supported by geological, geophysical, and geochemical exploration methods, they constitute a useful tool to shed light on the dynamic context of the geothermal resource setup and may provide answers to the challenging task of geothermal exploration. The Upper Rhine Graben (URG) is a data-rich geothermal system where deep fluid circulations occurring in the regional fault network are the probable origin of local thermal anomalies. Here, we present a current overview of our team’s efforts to integrate the impacts of the key physics as well as key factors controlling the geothermal anomalies in a fault-controlled geological setting in 3D physically consistent models at the regional scale. The study relies on the building of the first 3D numerical flow (using the discrete-continuum method) and mechanical models (using the distinct element method) at the URG scale. First, the key role of the regional fault network is taken into account using a discrete numerical approach. The geometry building is focused on the conceptualization of the 3D fault zone network based on structural interpretation and generic geological concepts and is consistent with the geological knowledge. This DFN (discrete fracture network) model is declined in two separate models (3D flow and stress) at the URG scale. Then, based on the main characteristics of the geothermal anomalies and the link with the physics considered, criteria are identified that enable the elaboration of indicators to use the results of the simulation and identify geothermally favourable areas. Then, considering the strong link between the stress, fluid flow, and geothermal resources, a cross-analysis of the results is realized to delineate favourable areas for geothermal resources. The results are compared with the existing thermal data at the URG scale and compared with knowledge gained through numerous studies. The good agreement between the delineated favourable areas and the locations of local thermal anomalies (especially the main one close to Soultz-sous-Forêts) demonstrates the key role of the regional fault network as well as stress and fluid flow on the setup of geothermal resources. Moreover, the very encouraging results underline the potential of the first 3D flow and 3D stress models at the URG scale to locate geothermal resources and offer new research opportunities.
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Weismüller, Christopher, Janos L. Urai, Michael Kettermann, Christoph von Hagke, and Klaus Reicherter. "Structure of massively dilatant faults in Iceland: lessons learned from high-resolution unmanned aerial vehicle data." Solid Earth 10, no. 5 (October 24, 2019): 1757–84. http://dx.doi.org/10.5194/se-10-1757-2019.
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Abstract. Normal faults in basalts develop massive dilatancy in the upper few hundred meters below the Earth's surface with corresponding interactions with groundwater and lava flow. These massively dilatant faults (MDFs) are widespread in Iceland and the East African Rift, but the details of their geometry are not well documented, despite their importance for fluid flow in the subsurface, geohazard assessment and geothermal energy. We present a large set of digital elevation models (DEMs) of the surface geometries of MDFs with 5–15 cm resolution, acquired along the Icelandic rift zone using unmanned aerial vehicles (UAVs). Our data present a representative set of outcrops of MDFs in Iceland, formed in basaltic sequences linked to the mid-ocean ridge. UAVs provide a much higher resolution than aerial/satellite imagery and a much better overview than ground-based fieldwork, bridging the gap between outcrop-scale observations and remote sensing. We acquired photosets of overlapping images along about 20 km of MDFs and processed these using photogrammetry to create high-resolution DEMs and orthorectified images. We use this dataset to map the faults and their damage zones to measure length, opening width and vertical offset of the faults and identify surface tilt in the damage zones. Ground truthing of the data was done by field observations. Mapped vertical offsets show typical trends of normal fault growth by segment coalescence. However, opening widths in map view show variations at much higher frequency, caused by segmentation, collapsed relays and tilted blocks. These effects commonly cause a higher-than-expected ratio of vertical offset and opening width for a steep normal fault at depth. Based on field observations and the relationships of opening width and vertical offset, we define three endmember morphologies of MDFs: (i) dilatant faults with opening width and vertical offset, (ii) tilted blocks (TBs) and (iii) opening-mode (mode I) fissures. Field observation of normal faults without visible opening invariably shows that these have an opening filled with recent sediment. TB-dominated normal faults tend to have the largest ratio of opening width and vertical offset. Fissures have opening widths up to 15 m with throw below a 2 m threshold. Plotting opening width versus vertical offset shows that there is a continuous transition between the endmembers. We conclude that for these endmembers, the ratio between opening width and vertical offset R can be reliably used to predict fault structures at depth. However, fractures associated with MDFs belong to one larger continuum and, consequently, where different endmembers coexist, a clear identification of structures solely via the determination of R is impossible.
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Dey, Sandip, and Solomon Tesfamariam. "Probabilistic Seismic Risk Analysis of Buried Pipelines Due to Permanent Ground Deformation for Victoria, BC." Geotechnics 2, no. 3 (August 31, 2022): 731–53. http://dx.doi.org/10.3390/geotechnics2030035.
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Buried continuous pipelines are prone to failure due to permanent ground deformation as a result of fault rupture. Since the failure mode is dependent on a number of factors, a probabilistic approach is necessary to correctly compute the seismic risk. In this study, a novel method to estimate regional seismic risk to buried continuous pipelines is presented. The seismic risk assessment method is thereafter illustrated for buried gas pipelines in the City of Victoria, British Columbia. The illustrated example considers seismic hazard from the Leech River Valley Fault Zone (LRVFZ). The risk assessment approach considers uncertainties of earthquake rupture, soil properties at the site concerned, geometric properties of pipes and operating conditions. Major improvements in this method over existing comparable studies include the use of stochastic earthquake source modeling and analytical Okada solutions to generate regional ground deformation, probabilistically. Previous studies used regression equations to define probabilistic ground deformations along a fault. Secondly, in the current study, experimentally evaluated 3D shell and continuum pipe–soil finite element models were used to compute pipeline responses. Earlier investigations used simple soil spring–beam element pipe models to evaluate the pipeline response. Finally, the current approach uses the multi-fidelity Gaussian process surrogate model to ensure efficiency and limit required computational resources. The developed multi-fidelity Gaussian process surrogate model was successfully cross-validated with high coefficients of determination of 0.92 and 0.96. A fragility curve was generated based on failure criteria from ALA strain limits. The seismic risks of pipeline failure due to compressive buckling and tensile rupture at the given site considered were computed to be 1.5 percent and 0.6 percent in 50 years, respectively.
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Olsen-Kettle, Louise, Hans Mühlhaus, and Christian Baillard. "A study of localization limiters and mesh dependency in earthquake rupture." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 368, no. 1910 (January 13, 2010): 119–30. http://dx.doi.org/10.1098/rsta.2009.0190.
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No complete physically consistent model of earthquake rupture exists that can fully describe the rich hierarchy of scale dependencies and nonlinearities associated with earthquakes. We study mesh sensitivity in numerical models of earthquake rupture and demonstrate that this mesh sensitivity may provide hidden clues to the underlying physics generating the rich dynamics associated with earthquake rupture. We focus on unstable slip events that occur in earthquakes when rupture is associated with frictional weakening of the fault. Attempts to simulate these phenomena directly by introducing the relevant constitutive behaviour leads to mesh-dependent results, where the deformation localizes in one element, irrespective of size. Interestingly, earthquake models with oversized mesh elements that are ill-posed in the continuum limit display more complex and realistic physics. Until now, the mesh-dependency problem has been regarded as a red herring—but have we overlooked an important clue arising from the mesh sensitivity? We analyse spatial discretization errors introduced into models with oversized meshes to show how the governing equations may change because of these error terms and give rise to more interesting physics.
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Ahmed, Barzan I., and Mohammed S. Al-Jawad. "Geomechanical modelling and two-way coupling simulation for carbonate gas reservoir." Journal of Petroleum Exploration and Production Technology 10, no. 8 (August 10, 2020): 3619–48. http://dx.doi.org/10.1007/s13202-020-00965-7.
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Abstract Geomechanical modelling and simulation are introduced to accurately determine the combined effects of hydrocarbon production and changes in rock properties due to geomechanical effects. The reservoir geomechanical model is concerned with stress-related issues and rock failure in compression, shear, and tension induced by reservoir pore pressure changes due to reservoir depletion. In this paper, a rock mechanical model is constructed in geomechanical mode, and reservoir geomechanics simulations are run for a carbonate gas reservoir. The study begins with assessment of the data, construction of 1D rock mechanical models along the well trajectory, the generation of a 3D mechanical earth model, and running a 4D geomechanical simulation using a two-way coupling simulation method, followed by results analysis. A dual porosity/permeability model is coupled with a 3D geomechanical model, and iterative two-way coupling simulation is performed to understand the changes in effective stress dynamics with the decrease in reservoir pressure due to production, and therefore to identify the changes in dual-continuum media conductivity to fluid flow and field ultimate recovery. The results of analysis show an observed effect on reservoir flow behaviour of a 4% decrease in gas ultimate recovery and considerable changes in matrix contribution and fracture properties, with the geomechanical effects on the matrix visibly decreasing the gas production potential, and the effect on the natural fracture contribution is limited on gas inflow. Generally, this could be due to slip flow of gas at the media walls of micro-extension fractures, and the flow contribution and fracture conductivity is quite sufficient for the volume that the matrixes feed the fractures. Also, the geomechanical simulation results show the stability of existing faults, emphasizing that the loading on the fault is too low to induce fault slip to create fracturing, and enhanced permeability provides efficient conduit for reservoir fluid flow in reservoirs characterized by natural fractures.
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Compastié, Maxime, Antonio López Martínez, Carolina Fernández, Manuel Gil Pérez, Stylianos Tsarsitalidis, George Xylouris, Izidor Mlakar, Michail Alexandros Kourtis, and Valentino Šafran. "PALANTIR: An NFV-Based Security-as-a-Service Approach for Automating Threat Mitigation." Sensors 23, no. 3 (February 2, 2023): 1658. http://dx.doi.org/10.3390/s23031658.
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Small and medium enterprises are significantly hampered by cyber-threats as they have inherently limited skills and financial capacities to anticipate, prevent, and handle security incidents. The EU-funded PALANTIR project aims at facilitating the outsourcing of the security supervision to external providers to relieve SMEs/MEs from this burden. However, good practices for the operation of SME/ME assets involve avoiding their exposure to external parties, which requires a tightly defined and timely enforced security policy when resources span across the cloud continuum and need interactions. This paper proposes an innovative architecture extending Network Function Virtualisation to externalise and automate threat mitigation and remediation in cloud, edge, and on-premises environments. Our contributions include an ontology for the decision-making process, a Fault-and-Breach-Management-based remediation policy model, a framework conducting remediation actions, and a set of deployment models adapted to the constraints of cloud, edge, and on-premises environment(s). Finally, we also detail an implementation prototype of the framework serving as evaluation material.
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Zhang, Hui, Baojun Ge, and Bin Han. "Real-Time Motor Fault Diagnosis Based on TCN and Attention." Machines 10, no. 4 (March 30, 2022): 249. http://dx.doi.org/10.3390/machines10040249.
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Motor failure can result in damage to resources and property. Real-time motor fault diagnosis technology can detect faults and diagnosis in time to prevent serious consequences caused by the continued operation of the machine. Neural network models can easily and accurately fault diagnose from vibration signals. However, they cannot notice faults in time. In this study, a deep learning model based on a temporal convolutional network (TCN) and attention is proposed for real-time motor fault diagnosis. TCN can extract features from shorter vibration signal sequences to allow the system to detect and diagnose faults faster. In addition, attention allows the model to have higher diagnostic accuracy. The experiments demonstrate that the proposed model is able to detect faults in time when they occur and has an excellent diagnostic accuracy.
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Bogusz, Piotr, Mariusz Korkosz, Adam Powrózek, Jan Prokop, and Piotr Wygonik. "Research of influence of open-winding faults on properties of brushless permanent magnets motor." Open Physics 15, no. 1 (December 29, 2017): 959–64. http://dx.doi.org/10.1515/phys-2017-0118.
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AbstractThe paper presents an analysis of influence of selected fault states on properties of brushless DC motor with permanent magnets. The subject of study was a BLDC motor designed by the authors for unmanned aerial vehicle hybrid drive. Four parallel branches per each phase were provided in the discussed 3-phase motor. After open-winding fault in single or few parallel branches, a further operation of the motor can be continued. Waveforms of currents, voltages and electromagnetic torque were determined in discussed fault states based on the developed mathematical and simulation models. Laboratory test results concerning an influence of open-windings faults in parallel branches on properties of BLDC motor were presented.
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Johnston, M. J. S., A. T. Linde, and D. C. Agnew. "Continuous borehole strain in the San Andreas fault zone before, during, and after the 28 June 1992, MW 7.3 Landers, California, earthquake." Bulletin of the Seismological Society of America 84, no. 3 (June 1, 1994): 799–805. http://dx.doi.org/10.1785/bssa0840030799.
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Abstract High-precision strain was observed with a borehole dilational strainmeter in the Devil's Punchbowl during the 11:58 UT 28 June 1992 MW 7.3 Landers earthquake and the large Big Bear aftershock (MW 6.3). The strainmeter is installed at a depth of 176 m in the fault zone approximately midway between the surface traces of the San Andreas and Punchbowl faults and is about 100 km from the 85-km-long Landers rupture. We have questioned whether unusual amplified strains indicating precursive slip or high fault compliance occurred on the faults ruptured by the Landers earthquake, or in the San Andreas fault zone before and during the earthquake, whether static offsets for both the Landers and Big Bear earthquakes agree with expectation from geodetic and seismologic models of the ruptures and with observations from a nearby two-color geodimeter network, and whether postseismic behavior indicated continued slip on the Landers rupture or local triggered slip on the San Andreas. We show that the strain observed during the earthquake at this instrument shows no apparent amplification effects. There are no indications of precursive strain in these strain data due to either local slip on the San Andreas or precursive slip on the eventual Landers rupture. The observations are generally consistent with models of the earthquake in which fault geometry and slip have the same form as that determined by either inversion of the seismic data or inversion of geodetically determined ground displacements produced by the earthquake. Finally, there are some indications of minor postseismic behavior, particularly during the month following the earthquake.
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Özarpacı, Seda, Uğur Doğan, Semih Ergintav, Ziyadin Çakır, Alpay Özdemir, Michael Floyd, and Robert Reilinger. "Present GPS velocity field along 1999 Izmit rupture zone: evidence for continuing afterslip 20 yr after the earthquake." Geophysical Journal International 224, no. 3 (November 19, 2020): 2016–27. http://dx.doi.org/10.1093/gji/ggaa560.
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SUMMARY In order to better assess earthquake hazards, it is vital to have a better understanding of the spatial and temporal characteristics of fault creep that occur on ruptured faults during the period following major earthquakes. Towards this end, we use new far-field GPS velocities from continuous stations (extending ∼50–70 km from the fault) and updated near-fault GPS survey observations, with high temporal and spatial density, to constrain active deformation along the Mw7.4, 1999 Izmit, Turkey Earthquake fault. We interpret and model deformation as resulting from post-seismic afterslip on the coseismic fault. In the broadest sense, our results demonstrate that logarithmically decaying post-seismic afterslip continues at a significant level 20 yr following 1999 Earthquake. Elastic models indicate substantially shallower apparent locking depths at present than prior to the 1999 Earthquake, consistent with continuing afterslip on the coseismic fault at depth. High-density, near-fault GPS observations indicate shallow creep on the upper 1–2 km of the coseismic fault, with variable rates, the highest and most clearly defined of which reach ∼12 mm yr−1 (10–15 mm yr−1, 95 per cent c.i.) near the epicentre between 2014–2016. This amounts to ∼half the long-term slip deficit rate.
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Gobert, James. "Corporate criminality: four models of fault." Legal Studies 14, no. 3 (November 1994): 393–410. http://dx.doi.org/10.1111/j.1748-121x.1994.tb00510.x.
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‘Corporation - an ingenious device for obtaining individual profit without individual responsibility.’(A Bierce The Devil’s Dictionary, 1958)The problem of how to hold a company criminally accountable for the harm produced in the course of its business activity continues to vex the English judiciary. The attempt to apply conventional criminal law to companies has not been a resounding success. This was perhaps predictable, as the relevant rules and doctrines had been developed in cases involving human defendants. Their transposition to an inanimate organizational entity such as a company was never going to be easy. Not only did the judges fail to rise to the challenge, however, they managed to construe the relevant law in a regressive manner that has all but insulated large companies from criminal liability.
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Ootes, Luke, William J. Davis, Valerie A. Jackson, and Otto van Breemen. "Chronostratigraphy of the Hottah terrane and Great Bear magmatic zone of Wopmay Orogen, Canada, and exploration of a terrane translation model." Canadian Journal of Earth Sciences 52, no. 12 (December 2015): 1062–92. http://dx.doi.org/10.1139/cjes-2015-0026.
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The Paleoproterozoic Hottah terrane is the westernmost exposed bedrock of the Canadian Shield and a critical component for understanding the evolution of the Wopmay Orogen. Thirteen new high-precision U–Pb zircon crystallization ages are presented and support field observations of a volcano-plutonic continuum from Hottah terrane through to the end of the Great Bear magmatism, from >1950 to 1850 Ma. The new crystallization ages, new geochemical data, and newly published detrital zircon U–Pb data are used to challenge hitherto accepted models for the evolution of the Hottah terrane as an exotic arc and microcontinent that arrived over a west-dipping subduction zone and collided with the Slave craton at ca. 1.88 Ga. Although the Hottah terrane does have a tectonic history that is distinct from that of the neighbouring Slave craton, it shares a temporal history with a number of domains to the south and east — domains that were tied to the Slave craton by ca. 1.97 Ga. It is interpreted herein that Hottah terrane began to the south of its current position and evolved in an active margin over an always east-dipping subduction system that began prior to ca. 2.0 Ga and continued to ca. 1.85 Ga, and underwent tectonic switching and migration. The stratigraphy of the ca. 1913–1900 Ma Hottah plutonic complex and Bell Island Bay Group includes a subaerial rifting arc sequence, followed by basinal opening represented by marginal marine quartz arenite and overlying ca. 1893 Ma pillowed basalt flows and lesser rhyodacites. We interpret this stratigraphy to record Hottah terrane rifting off its parental arc crust — in essence the birth of the new Hottah terrane. This model is similar to rapidly rifting arcs in active margins — for example, modern Baja California. These rifts generally occur at the transition between subduction zones (e.g., Cocos–Rivera plates) and transtensional shear zones (e.g., San Andreas fault), and we suggest that extension-driven transtensional shearing, or, more simply, terrane translation, was responsible for the evolution of Bell Island Bay Group stratigraphy and that it transported this newly born Hottah terrane laterally (northward in modern coordinates), arriving adjacent to the Slave craton at ca. 1.88 Ga. Renewed east-dipping subduction led to the Great Bear arc flare-up at ca. 1876 Ma, continuing to ca. 1869 Ma. This was followed by voluminous Great Bear plutonism until ca. 1855 Ma. The model implies that it was the westerly Nahanni terrane and its subducting oceanic crust that collided with this active margin, shutting down the >120 million year old, east-dipping subduction system.
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McGregor, Ian S., and Nathan W. Onderdonk. "Late Pleistocene rates of rock uplift and faulting at the boundary between the southern Coast Ranges and the western Transverse Ranges in California from reconstruction and luminescence dating of the Orcutt Formation." Geosphere 17, no. 3 (March 24, 2021): 932–56. http://dx.doi.org/10.1130/ges02274.1.
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Abstract The western Transverse Ranges and southern Coast Ranges of California are lithologically similar but have very different styles and rates of Quaternary deformation. The western Transverse Ranges are deformed by west-trending folds and reverse faults with fast rates of Quaternary fault slip (1–11 mm/yr) and uplift (1–7 mm/yr). The southern Coast Ranges, however, are primarily deformed by northwest-trending folds and right-lateral strike-slip faults with much slower slip rates (3 mm/yr or less) and uplift rates (<1 mm/yr). Faults and folds at the boundary between these two structural domains exhibit geometric and kinematic characteristics of both domains, but little is known about the rate of Quaternary deformation along the boundary. We used a late Pleistocene sedimentary deposit, the Orcutt Formation, as a marker to characterize deformation within the boundary zone over the past 120 k.y. The Orcutt Formation is a fluvial deposit in the Santa Maria Basin that formed during regional planation by a broad fluvial system that graded into a shoreline platform at the coast. We used post-infrared–infrared-stimulated luminescence (pIR-IRSL) dating to determine that the Orcutt Formation was deposited between 119 ± 8 and 85 ± 6 ka, coincident with oxygen isotope stages 5e-a paleo–sea-level highstands and regional depositional events. The deformed Orcutt basal surface closely follows the present-day topography of the Santa Maria Basin and is folded by northwest-trending anticlines that are a combination of fault-propagation and fault-bend-folding controlled by deeper thrust faults. Reconstructions of the Orcutt basal surface and forward modeling of balanced cross sections across the study area allowed us to measure rock uplift rates and fault slip rates. Rock uplift rates at the crests of two major anticlinoria are 0.9–4.9 mm/yr, and the dip-slip rate along the blind fault system that underlies these folds is 5.6–6.7 mm/yr. These rates are similar to those reported from the Ventura area to the southeast and indicate that the relatively high rates of deformation in the western Transverse Ranges are also present along the northern boundary zone. The deformation style and rates are consistent with models that attribute shortening across the Santa Maria Basin to accommodation of clockwise rotation of the western Transverse Ranges and suggest that rotation has continued into late Quaternary time.
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Singh, Ompal, Saurabh Panwar, and P. K. Kapur. "Determining Software Time-to-Market and Testing Stop Time when Release Time is a Change-Point." International Journal of Mathematical, Engineering and Management Sciences 5, no. 2 (April 1, 2020): 208–24. http://dx.doi.org/10.33889/ijmems.2020.5.2.017.
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In software engineering literature, numerous software reliability growth models have been designed to evaluate and predict the reliability of the software products and to measure the optimal time-to-market of the software systems. Most existing studies on software release time assessment assumes that when software is released, its testing process is terminated. In practice, however, the testing team releases the software product first and continues the testing process for an added period in the operational phase. Therefore, in this study, a coherent reliability growth model is developed to predict the expected reliability of the software product. The debugging process is considered imperfect as new faults can be introduced into the software during each fault removal. The proposed model assumes that the fault observation rate of the testing team modifies after the software release. The release time of the software is therefore regarded as the change-point. It has been established that the veracity of the performance of the growth models escalates by incorporating the change-point theory. A unified approach is utilized to model the debugging process wherein both testers and users simultaneously identify the faults in the post-release testing phase. A joint optimization problem is formulated based on the two decision criteria: cost and reliability. In order to assimilate the manager’s preferences over these two criteria, a multi-criteria decision-making technique known as multi-attribute utility theory is employed. A numerical illustration is further presented by using actual data sets from the software project to determine the optimal software time-to-market and testing termination time.
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Mhamdi, Lotfi, Lobna Belkacem, Hedi Dhouibi, and Zineb Simeu Abazi. "Using Hybrid Automata for Diagnosis of Hybrid Dynamical Systems." International Journal of Electrical and Computer Engineering (IJECE) 5, no. 6 (December 1, 2015): 1396. http://dx.doi.org/10.11591/ijece.v5i6.pp1396-1406.
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Physical systems can fail. For this reason the problem of identifying and reacting to faults has received a large attention in the control and computer science communities. In this paper we study the fault diagnosis problem and modeling of Hybrid Dynamical Systems (HDS). Generally speaking, HDS is a system mixing continuous and discrete behaviors that cannot be faithfully modeled neither by using formalism with continuous dynamics only nor by a formalism including only discrete dynamics. We use the well known framework of hybrid automata for modeling hybrid systems, because they combine the continous and discretes parts on the same structure. Hybrid automaton is a states-transitions graph, whose dynamic evolution is represented by discretes and continous steps alternations, also, continous evolution happens in the automaton apexes, while discrete evolution is realized by transitions crossing (arcs) of the graph. Their simulation presents many problems mainly the synchronisation between the two models. Stateflow, used to describe the discrete model, is co-ordinated with Matlab, used to describe the continuous model. This article is a description of a case study, which is a two tanks system.
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Wells, Ray E., Richard J. Blakely, and Sean Bemis. "Northward migration of the Oregon forearc on the Gales Creek fault." Geosphere 16, no. 2 (February 6, 2020): 660–84. http://dx.doi.org/10.1130/ges02177.1.
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Abstract The Gales Creek fault (GCF) is a 60-km-long, northwest-striking dextral fault system (west of Portland, Oregon) that accommodates northward motion and uplift of the Oregon Coast Range. New geologic mapping and geophysical models confirm inferred offsets from earlier geophysical surveys and document ∼12 km of right-lateral offset of a basement high in Eocene Siletz River Volcanics since ca. 35 Ma and ∼8.8 km of right-lateral separation of Miocene Columbia River Basalt at Newberg, Oregon, since 15 Ma (∼0.62 ± 0.12 mm/yr, average long-term rate). Relative uplift of Eocene Coast Range basalt basement west of the fault zone is at least 5 km based on depth to basement under the Tualatin Basin from a recent inversion of gravity data. West of the city of Forest Grove, the fault consists of two subparallel strands ∼7 km apart. The westernmost, Parsons Creek strand, forms a linear valley southward to Henry Hagg Lake, where it continues southward to Newberg as a series of en echelon strands forming both extensional and compressive step-overs. Compressive step-overs in the GCF occur at intersections with ESE-striking sinistral faults crossing the Coast Range, suggesting the GCF is the eastern boundary of an R′ Riedel shear domain that could accommodate up to half of the ∼45° of post–40 Ma clockwise rotation of the Coast Range documented by paleomagnetic studies. Gravity and magnetic anomalies suggest the western strands of the GCF extend southward beneath Newberg into the Northern Willamette Valley, where colinear magnetic anomalies have been correlated with the Mount Angel fault, the proposed source of the 1993 M 5.7 Scotts Mills earthquake. The potential-field data and water-well data also indicate the eastern, Gales Creek strand of the fault may link to the NNW-striking Canby fault through the E-W Beaverton fault to form a 30-km-wide compressive step-over along the south side of the Tualatin Basin. LiDAR data reveal right-lateral stream offsets of as much as 1.5 km, shutter ridges, and other youthful geomorphic features for 60 km along the geophysical and geologic trace of the GCF north of Newberg, Oregon. Paleoseismic trenches document Eocene bedrock thrust over 250 ka surficial deposits along a reverse splay of the fault system near Yamhill, Oregon, and Holocene motion has been recently documented on the GCF along Scoggins Creek and Parsons Creek. The GCF could produce earthquakes in excess of Mw 7, if the entire 60 km segment ruptured in one earthquake. The apparent subsurface links of the GCF to other faults in the Northern Willamette Valley suggest that other faults in the system may also be active.
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Wang, Kang, Douglas S. Dreger, Elisa Tinti, Roland Bürgmann, and Taka’aki Taira. "Rupture Process of the 2019 Ridgecrest, California Mw 6.4 Foreshock and Mw 7.1 Earthquake Constrained by Seismic and Geodetic Data." Bulletin of the Seismological Society of America 110, no. 4 (July 7, 2020): 1603–26. http://dx.doi.org/10.1785/0120200108.
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ABSTRACT The 2019 Ridgecrest earthquake sequence culminated in the largest seismic event in California since the 1999 Mw 7.1 Hector Mine earthquake. Here, we combine geodetic and seismic data to study the rupture process of both the 4 July Mw 6.4 foreshock and the 6 July Mw 7.1 mainshock. The results show that the Mw 6.4 foreshock rupture started on a northwest-striking right-lateral fault, and then continued on a southwest-striking fault with mainly left-lateral slip. Although most moment release during the Mw 6.4 foreshock was along the southwest-striking fault, slip on the northwest-striking fault seems to have played a more important role in triggering the Mw 7.1 mainshock that happened ∼34 hr later. Rupture of the Mw 7.1 mainshock was characterized by dominantly right-lateral slip on a series of overall northwest-striking fault strands, including the one that had already been activated during the nucleation of the Mw 6.4 foreshock. The maximum slip of the 2019 Ridgecrest earthquake was ∼5 m, located at a depth range of 3–8 km near the Mw 7.1 epicenter, corresponding to a shallow slip deficit of ∼20%–30%. Both the foreshock and mainshock had a relatively low-rupture velocity of ∼2 km/s, which is possibly related to the geometric complexity and immaturity of the eastern California shear zone faults. The 2019 Ridgecrest earthquake produced significant stress perturbations on nearby fault networks, especially along the Garlock fault segment immediately southwest of the 2019 Ridgecrest rupture, in which the coulomb stress increase was up to ∼0.5 MPa. Despite the good coverage of both geodetic and seismic observations, published coseismic slip models of the 2019 Ridgecrest earthquake sequence show large variations, which highlight the uncertainty of routinely performed earthquake rupture inversions and their interpretation for underlying rupture processes.
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Vásquez Capacho, John William. "Diagnosis in industrial processes." Visión electrónica 11, no. 2 (October 27, 2018): 222–32. http://dx.doi.org/10.14483/22484728.14621.
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This article describes the most important aspects in the diagnosis of failures on industrial processes. An analysis of process safety is seen from monitoring tools including expert systems as well as intelligent hybrid models. The article continues to identify aspects such as reliability, risk analysis, fault diagnosis techniques and industrial control and safety systems in processes. Reliability and risk analysis provide important information in a process safety tool; analyzes such as HAZOP, FMEA, Fault trees and Bow tie are described through this article. Then compiled and summarized the different techniques and models of fault diagnosis concluding with a presentation of control and safety systems in an industrial process
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Robson, Alexander, Rosalind King, and Simon Holford. "Normal fault growth and segment linkage in a gravitationally detached delta system: evidence from 3D seismic reflection data from the Ceduna Sub-basin, Great Australian Bight." APPEA Journal 55, no. 2 (2015): 467. http://dx.doi.org/10.1071/aj14102.
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The authors used three-dimensional (3D) seismic reflection data from the central Ceduna Sub-Basin, Australia, to establish the structural evolution of a linked normal fault assemblage at the extensional top of a gravitationally driven delta system. The fault assemblage presented is decoupled at the base of a marine mud from the late Albian age. Strike-linkage has created a northwest–southeast oriented assemblage of normal fault segments and dip-linkage through Santonian strata, which connects a post-Santonian normal fault system to a Cenomanian-Santonian listric fault system. Cenomanian-Santonian fault growth is on the kilometre scale and builds an underlying structural grain, defining the geometry of the post-Santonian fault system. A fault plane dip-angle model has been created and established through simplistic depth conversion. This converts throw into fault plane dip-slip displacement, incorporating increasing heave of a listric fault and decreasing in dip-angle with depth. The analysis constrains fault growth into six evolutionary stages: early Cenomanian nucleation and radial growth of isolated fault segments; linkage of fault segments by the latest Cenomanian; latest Santonian Cessation of fault growth; erosion and heavy incision during the continental break-up of Australia and Antarctica (c. 83 Ma); vertically independent nucleation of the post-Santonian fault segments with rapid length establishment before significant displacement accumulation; and, continued displacement into the Cenozoic. The structural evolution of this fault system is compatible with the isolated fault model and segmented coherent fault model, indicating that these fault growth models do not need to be mutually exclusive to the growth of normal fault assemblages.
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Liu, Dian, Yong Qin, Yiying Zhao, Weijun Yang, Haijun Hu, Ning Yang, and Bing Liu. "Fault Early Warning Model for High-Speed Railway Train Based on Feature Contribution and Causal Inference." Sensors 22, no. 23 (November 25, 2022): 9184. http://dx.doi.org/10.3390/s22239184.
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The demands for model accuracy and computing efficiency in fault warning scenarios are increasing as high-speed railway train technology continues to advance. The black box model is difficult to interpret, making it impossible for this technology to be widely adopted in the railway industry, which has strict safety regulations. This paper proposes a fault early warning machine learning model based on feature contribution and causal inference. First, the contributions of the features are calculated through the Shapley additive explanations model. Then, causal relationships are discovered through causal inference models. Finally, data from causal and high-contribution time series are applied to the model. Ablation tests are conducted with the Naïve Bayes, Gradient Boosting Decision Tree, eXtreme Gradient Boosting, and other models in order to confirm the efficiency of the method based on early warning data regarding the on-site high-speed train traction equipment circuit board failure. The findings indicate that the strategy improves the evaluation markers, including the early warning accuracy, precision, recall, and F1 score, by an average of more than 10%. There is a 35% improvement in the computing efficiency, and the model can provide feature causal graph verification for expert product decision-making.
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James, S. J. "Brent Field Reservoir Modeling: Laying the Foundations of a Brown Field Redevelopment." SPE Reservoir Evaluation & Engineering 2, no. 01 (February 1, 1999): 104–11. http://dx.doi.org/10.2118/54700-pa.
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Summary The Brent Field was discovered in 1971. It is now a mature asset and, in order to increase oil and gas ultimate recovery, will commence depressurization in 1997. The redevelopment of the field has been underpinned by extensive static and dynamic modeling studies. Developments in geological computing and the numerical processing power of reservoir simulation platforms significantly improved the quality of the Brent Field static and dynamic models. The static models have been used for a range of studies including gas cap volumetrics and bypassed oil investigations. Their functionality provides significant scope for target sizing as a basis for selecting the appropriate reservoir access well technology. Introduction The Brent Field, located 100 miles north east of Lerwick, Shetland Islands (Fig. 1) was discovered by well 211/29-1 in 1971. With total hydrocarbons initially in place of some 3.8 MMMbbl oil and 7.5 Tscf gas, the Brent Field ranked as one of the largest fields in the northern North Sea. Following 20 years of production, remaining reserves are estimated to be some 400 MMbbl oil and 2.6 Tscf gas and in these terms the Brent Field continues to rank as the largest field in the U.K. Sector of the North Sea. The Brent Field is a mature asset. Facilities comprise four platforms providing a total of 154 well slots. Oil export is via the Brent systems pipeline to Sullom Voe and gas export via the FLAGS line to St. Fergus. Production from the extensive West Flank area commenced in 1976 and by January 1997 cumulative production amounted to 1.6 MMMbbl oil, some 80% of anticipated waterflood ultimate recovery, and 3.2 Tscf gas. In order to significantly increase ultimate recovery through field depressurization, an extensive brown field redevelopment project, costing £1.3 billion, was initiated in 1994. This is now reaching completion with depressurization commencing in 1997 and low-pressure operation in the year 2000. This project has extended the life of the field and increased ultimate recovery. The redevelopment of the Brent Field involved extensive static and dynamic reservoir modeling studies,1 which will continue to guide reservoir management during depressurization. This paper reviews the development of the current generation of static reservoir models and illustrates their use, not only as the basis for dynamic studies but also in delineating areas of bypassed oil and monitoring gas cap volumetrics. Geological Summary The Brent Field is a north-south oriented, westerly dipping fault block about 10.6×3.1 miles in size, located within the central part of a fault terrace on the western margin of the Viking Graben (Fig. 1). The terrace can be traced over some 40 miles from the North Alwyn Field in the south to the Statfjord Field in the north. It is some 12 miles wide from the western boundary, the Hutton-Dunlin-Murchison fault zone, to the eastern boundary, which is defined by a series of faults just to the east of the crestal slump area of the field. The field comprises two crestally eroded reservoirs, the Upper Triassic/Lower Jurassic Statfjord Formation and the Middle Jurassic Brent Group, which are separated by the nonreservoir shales of the Lower to Middle Jurassic Dunlin Group (Fig. 2). The Statfjord reservoir, which is about 1,000 ft in thickness, is composed of a lower fluvial jigsaw/labyrinth reservoir-type2 interval (the Eiriksson and Raude Members) and an upper layer-cake shoreface sand interval (the Nansen Member) (Fig. 3). The Brent reservoir, which is about 1,000 ft in thickness, is composed of the Tarbert, Ness, Etive, Rannoch, and Broom formations of which the Ness formation is mainly a delta plain jigsaw/labyrinth reservoir-type2 and the others are shallow marine layer-cake and jigsaw types (Fig. 4). Two different structural styles are superimposed on the Brent Field reservoir sequence (Fig. 2). The gently dipping West Flank area forms the up-dip eastern margin of the fault terrace. A series of steeply dipping west-east faults segment the West Flank and define the Main, Graben, and Horst Block elements of the Brent Field and partially delimit the Brent North area, Brent South, and Strathspey Fields (Fig. 1, Fig. 5). The development of the eastern terrace margin fault system was associated with the collapse of gravitationally unstable fault scarps and the formation of the crestal slope degradation complexes (which are referred to as slumps in field terminology). Separate slump systems formed within the Brent Group, where the master listric faults sole out in the Dunlin Group, and in the Statfjord formation where they sole out in the shaly lower part of the formation (Fig. 2). The combination of reservoir sequence and structural style has resulted in the four different reservoir entities that comprise the main Brent Field; the West Flank Statfjord, the West Flank Brent, the Statfjord Slumps, and the Brent Slumps. A similar combination is also present in the Brent South Field and the Brent North area. Field Development Summary Development of the Statfjord and Brent West Flank reservoirs commenced in 1976. Both were developed with north-south rows of producers, those dedicated to the Statfjord being crestally positioned and those to the Brent targeted in mid-oil column positions at the top of each of the major reservoir units (Fig. 6). Pressure support for both reservoirs was provided by down-dip water injection wells. Gas produced excess to export requirements was reinjected into the reservoirs. This development strategy and the highly stratified nature of both reservoirs led to the evolution of numerous thin oil rims which, with continuing production, have become thinner and moved upwards into the originally gas-bearing crest of the West Flank. The future development of the West Flank reservoirs is focused on the depressurization and low-pressure operation.1,3
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Echeberria-Barrio, Xabier, Amaia Gil-Lerchundi, Raul Orduna-Urrutia, and Iñigo Mendialdua. "Optimized Parameter Search Approach for Weight Modification Attack Targeting Deep Learning Models." Applied Sciences 12, no. 8 (April 7, 2022): 3725. http://dx.doi.org/10.3390/app12083725.
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Deep neural network models have been developed in different fields, bringing many advances in several tasks. However, they have also started to be incorporated into tasks with critical risks. That worries researchers who have been interested in studying possible attacks on these models, discovering a long list of threats from which every model should be defended. The weight modification attack is presented and discussed among researchers, who have presented several versions and analyses about such a threat. It focuses on detecting multiple vulnerable weights to modify, misclassifying the desired input data. Therefore, analysis of the different approaches to this attack helps understand how to defend against such a vulnerability. This work presents a new version of the weight modification attack. Our approach is based on three processes: input data clusterization, weight selection, and modification of the weights. Data clusterization allows a directed attack to a selected class. Weight selection uses the gradient given by the input data to identify the most-vulnerable parameters. The modifications are incorporated in each step via limited noise. Finally, this paper shows how this new version of fault injection attack is capable of misclassifying the desired cluster completely, converting the 100% accuracy of the targeted cluster to 0–2.7% accuracy, while the rest of the data continues being well-classified. Therefore, it demonstrates that this attack is a real threat to neural networks.
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Dooley, Tim P., and Michael R. Hudec. "Extension and inversion of salt-bearing rift systems." Solid Earth 11, no. 4 (July 6, 2020): 1187–204. http://dx.doi.org/10.5194/se-11-1187-2020.
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Abstract. We used physical models to investigate the structural evolution of segmented extensional rifts containing syn-rift evaporites and their subsequent inversion. An early stage of extension generated structural topography consisting of a series of en-échelon graben. Our salt analog filled these graben and the surroundings before continued extension and, finally, inversion. During post-salt extension, deformation in the subsalt section remained focused on the graben-bounding fault systems, whereas deformation in suprasalt sediments was mostly detached, forming a sigmoidal extensional minibasin system across the original segmented graben array. Little brittle deformation was observed in the post-salt section. Sedimentary loading from the minibasins drove salt up onto the footwalls of the subsalt faults, forming diapirs and salt-ridge networks on the intra-rift high blocks. Salt remobilization and expulsion from beneath the extensional minibasins was enhanced along and up the major relay or transfer zones that separated the original sub-salt grabens, forming major diapirs in these locations. Inversion of this salt-bearing rift system produced strongly decoupled shortening belts in basement and suprasalt sequences. Suprasalt deformation geometries and orientations are strongly controlled by the salt diapir and ridge network produced during extension and subsequent downbuilding. Thrusts are typically localized at minibasin margins where the overburden was thinnest, and salt had risen diapirically on the horst blocks. In the subsalt section, shortening strongly inverted sub-salt grabens, which uplifted the suprasalt minibasins. New pop-up structures also formed in the subsalt section. Primary welds formed as suprasalt minibasins touched down onto inverted graben. Model geometries compare favorably to natural examples such as those in the Moroccan High Atlas.
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Ryan, Georgina, George Bernardel, John Kennard, Andrew T. Jones, Graham Logan, and Nadege Rollet. "A pre-cursor extensive Miocene reef system to the Rowley Shoals reefs, Western Australia: evidence for structural control of reef growth or natural hydrocarbon seepage?" APPEA Journal 49, no. 1 (2009): 337. http://dx.doi.org/10.1071/aj08021.
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Numerous Miocene reefs and related carbonate build-ups have been identified in the Rowley Shoals region of the central North West Shelf, offshore Western Australia. The reefs form part of an extensive Miocene reef tract over 1,600 km long, which extended northward into the Browse and Bonaparte basins and southward to North West Cape in the Carnarvon Basin—comparable in length to the modern Great Barrier Reef. Growth of the vast majority of these Miocene reefs failed to keep pace with relative sea-level changes in the latest Miocene, whereas reef growth continued on the central North West Shelf to form the three present-day atolls of the Rowley Shoals: Mermaid, Clerke and Imperieuse reefs. In the Rowley Shoals region, scattered small build-ups and local reef complexes were first established in the Early Miocene, but these build-ups were subsequently terminated at a major Mid Miocene sequence boundary. Widespread buildups and atoll reefs were re-established in the Middle Miocene, and the internal stacking geometries of the reefs appear to relate to distinct growth phases that are correlated with eustatic sea-level fluctuations. These geometries include: a basal aggradational buildup of early Middle Miocene age; a strongly progradational growth phase in the late Middle to early Late Miocene that constructed large reef atolls with infilling lagoon deposits; and a back-stepped aggradational growth phase that formed smaller reef caps in the early–latest Late Miocene. Growth of the majority of the reefs ceased at a major sea-level fall in the Late Miocene (Messinian), and only the reefs of the present-day Rowley Shoals (Mermaid, Clerke and Imperieuse reefs, as well as a drowned shoal to the southwest of Imperieuse Reef) continued to grow after this event. Growth of the Rowley Shoals reefs continued to keep pace with Pliocene-Recent sea-level changes, whereas the surrounding shelf subsided to depths of 230–440 m. We conclude that initial reef growth in the Rowley Shoals region was controlled by transpressional reactivation and structuring of the Mermaid Fault Zone during the early stage of collision between the Australian and Eurasian plates. During this structural reactivation, seabed fault scarps and topographic highs likely provided ideal sites for the initiation of reef growth. The subsequent growth and selective demise of the reefs was controlled by the interplay of eustatic sea-level variations and differential subsidence resulting from continued structural reactivation of the Mermaid Fault Zone. In contrast to models proposed in other regions, there is no direct evidence that active or palaeo hydrocarbon seepage triggered or controlled growth of the Rowley Shoals reefs or their buried Miocene predecessors.
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Duboeuf, Laure, Anna Maria Dichiarante, and Volker Oye. "Interplay of large-scale tectonic deformation and local fluid injection investigated through seismicity patterns at the Reykjanes Geothermal Field, Iceland." Geophysical Journal International 228, no. 3 (October 19, 2021): 1866–86. http://dx.doi.org/10.1093/gji/ggab423.
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SUMMARY Occurrence of seismicity sequences as consequence of fluid injection or extraction has long been studied and documented. Causal relations between injection parameters, such as injection pressure, injection rates, total injected volumes and injectivity, with seismicity derived parameters, such as seismicity rate, cumulative seismic moment, distance of seismicity (RT-plot), b-values, etc. have been derived. In addition, reservoir engineering parameters such as permeability/porosity relations and flow types play a role together with geology knowledge on fault and fracture properties, influenced by the stress field on different scales. In this paper, we study observed seismicity related to water injection at the Reykjanes Geothermal Field, Iceland. The region near the injection well did not experience seismicity before the start of injection. However, we observed continued seismic activity during the 3 months of injection in 2015, resulting in a cloud of about 700 events ranging in magnitude from Mw 0.7 to 3.3. We re-located these events using a modified double-difference algorithm and determined focal mechanism of event subsets. Characteristic for the site is that the events are bound to about 4 km distance to the injection point, and moreover known faults seem to act as barrier to fluids and seismicity. Several repeating sequences of seismicity, defined as bursts of seismicity have hypocenter migration velocities larger than 4 km d–1 and their dominant direction of propagation is away from the injection point towards larger depths. The seismic events within the bursts lack larger magnitude events, have elevated b-values (∼1.5) and consist of many multiplets. Except from the coinciding onset of seismicity with the start of fluid injection, no correlation between injection rates and volumes could be identified, neither could hydraulic diffusivity models explain observed seismicity patterns. Comparison of our results with investigations on background seismicity from 1995 to 2019 and from a seismic swarm in 1972 revealed similar focal mechanism patterns and burst-like seismicity patterns. We finally present a conceptual model where we propose that the observed seismicity patterns represent a stress release mechanism in the area close to the injection well, controlled by an interplay of local pore pressure and stress field changes with continued extensional stress build up at the Reykjanes Ridge.
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Trop, Jeffrey M., Jeff Benowitz, Ronald B. Cole, and Paul O’Sullivan. "Cretaceous to Miocene magmatism, sedimentation, and exhumation within the Alaska Range suture zone: A polyphase reactivated terrane boundary." Geosphere 15, no. 4 (June 26, 2019): 1066–101. http://dx.doi.org/10.1130/ges02014.1.
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AbstractThe Alaska Range suture zone exposes Cretaceous to Quaternary marine and nonmarine sedimentary and volcanic rocks sandwiched between oceanic rocks of the accreted Wrangellia composite terrane to the south and older continental terranes to the north. New U-Pb zircon ages, 40Ar/39Ar, ZHe, and AFT cooling ages, geochemical compositions, and geological field observations from these rocks provide improved constraints on the timing of Cretaceous to Miocene magmatism, sedimentation, and deformation within the collisional suture zone. Our results bear on the unclear displacement history of the seismically active Denali fault, which bisects the suture zone. Newly identified tuffs north of the Denali fault in sedimentary strata of the Cantwell Formation yield ca. 72 to ca. 68 Ma U-Pb zircon ages. Lavas sampled south of the Denali fault yield ca. 69 Ma 40Ar/39Ar ages and geochemical compositions typical of arc assemblages, ranging from basalt-andesite-trachyte, relatively high-K, and high concentrations of incompatible elements attributed to slab contribution (e.g., high Cs, Ba, and Th). The Late Cretaceous lavas and bentonites, together with regionally extensive coeval calc-alkaline plutons, record arc magmatism during contractional deformation and metamorphism within the suture zone. Latest Cretaceous volcanic and sedimentary strata are locally overlain by Eocene Teklanika Formation volcanic rocks with geochemical compositions transitional between arc and intraplate affinity. New detrital-zircon data from the modern Teklanika River indicate peak Teklanika volcanism at ca. 57 Ma, which is also reflected in zircon Pb loss in Cantwell Formation bentonites. Teklanika Formation volcanism may reflect hypothesized slab break-off and a Paleocene–Eocene period of a transform margin configuration. Mafic dike swarms were emplaced along the Denali fault from ca. 38 to ca. 25 Ma based on new 40Ar/39Ar ages. Diking along the Denali fault may have been localized by strike-slip extension following a change in direction of the subducting oceanic plate beneath southern Alaska from N-NE to NW at ca. 46–40 Ma. Diking represents the last recorded episode of significant magmatism in the central and eastern Alaska Range, including along the Denali fault. Two tectonic models may explain emplacement of more primitive and less extensive Eocene–Oligocene magmas: delamination of the Late Cretaceous–Paleocene arc root and/or thickened suture zone lithosphere, or a slab window created during possible Paleocene slab break-off. Fluvial strata exposed just south of the Denali fault in the central Alaska Range record synorogenic sedimentation coeval with diking and inferred strike-slip displacement. Deposition occurred ca. 29 Ma based on palynomorphs and the youngest detrital zircons. U-Pb detrital-zircon geochronology and clast compositional data indicate the fluvial strata were derived from sedimentary and igneous bedrock presently exposed within the Alaska Range, including Cretaceous sources presently exposed on the opposite (north) side of the fault. The provenance data may indicate ∼150 km or more of dextral offset of the ca. 29 Ma strata from inferred sediment sources, but different amounts of slip are feasible.Together, the dike swarms and fluvial strata are interpreted to record Oligocene strike-slip movement along the Denali fault system, coeval with strike-slip basin development along other segments of the fault. Diking and sedimentation occurred just prior to the onset of rapid and persistent exhumation ca. 25 Ma across the Alaska Range. This phase of reactivation of the suture zone is interpreted to reflect the translation along and convergence of southern Alaska across the Denali fault driven by highly coupled flat-slab subduction of the Yakutat microplate, which continues to accrete to the southern margin of Alaska. Furthermore, a change in Pacific plate direction and velocity at ca. 25 Ma created a more convergent regime along the apex of the Denali fault curve, likely contributing to the shutting off of near-fault extension-facilitated arc magmatism along this section of the fault system and increased exhumation rates.
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Hall, Melvin E. "Evaluation’s Race Problem in the United States." American Journal of Evaluation 39, no. 4 (October 22, 2018): 569–83. http://dx.doi.org/10.1177/1098214018792624.
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Despite political and rhetorical pronouncements of a reduction in racism, growing inequity in U.S. society continues to feature race as a prominent fault line with no evidence of reduction on the horizon. Of significant concern is the degree to which inequity among racially identified subgroups of the population link to policies and practices of local, state, and federal government and thereby influence the operation and evaluation of important programs and services. Evaluation as a principal tool of knowledge creation on behalf of government and the public trust must examine its role with respect to these alarming trends and potential vulnerability. The author examines how race and racism (particularly as focused on African American communities) may influence the theories, models, practices, and techniques of evaluation and calls for creation of an ongoing forum in the American Journal of Evaluation where these critical issues can receive thoughtful and continuous attention from the field.
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Mao, Yuyang, Xiaolong Wang, and Zhiqiang Wang. "Analysis of Wind Power Grid Connection Based on MATLAB." E3S Web of Conferences 267 (2021): 01050. http://dx.doi.org/10.1051/e3sconf/202126701050.
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As the proportion of new energy sources such as wind power and photovoltaics in the power system continues to increase, their volatility and intermittentness have also brought new challenges to the stable operation of the power grid. The impact of the decline in power quality caused by a large number of wind power grids has become increasingly significant. This article analyzes and summarizes the development, status quo of wind power and the current problems of a large number of wind power grid connections. First, it briefly describes the history of wind power and the current development of wind power, and uses MATLAB to establish models of variable speed wind turbines connected to the grid. The models are used to analyze the output characteristics of wind turbines under normal operating conditions and faulty operating conditions. Finally, the impact of a large number of wind power grids on the power system is studied.
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ΠΑΠΑΖΑΧΟΣ, Β. Κ. "Active Tectonics in the Aegean and surrounding area." Bulletin of the Geological Society of Greece 34, no. 6 (January 1, 2002): 2237. http://dx.doi.org/10.12681/bgsg.16865.
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The purpose of the present article is to summarize the current scientific knowledge related to the active tectonics of the Aegean and surrounding area (active deformation, lithospheric plate-motions, etc.), as well as describe the main information (data, methods, etc.) which were used to obtain this knowledge. It is pointed out that the understanding of active tectonics has not only theoretical but also practical interest, as it contributes to the solution of problems of direct social impact such as the problem of earthquake prediction. It is shown that most of our present knowledge relies on geophysical, geological and geodetic data. Due to the fact that the Aegean exhibits a variety of geomorphological structures and on going geophysical processes, it has been one of the modern "natural laboratories" where scientists from different parts of the world are working and verify various hypotheses related to our current view of World Tectonics. The Aegean exhibits the typical characteristics of a subduction area, such as the Hellenic Arc (a typical island arc), the Aegean Sea (a marginal sea with typical geomorphological characteristics) and the Collision Zone between the Balkan peninsula and the southwestern Adriatic. A large number of results concerning the Aegean area relies on the use of the spatial distribution of earthquake foci. Accurate data of the last two decades showed that most shallow earthquakes are generated on the shallowest part of the crust (upper 20km) and only along the southern Aegean subduction zone can their depth reach up to 60km. Papazachos and Comninakis (1969/70, 1971) were the first to determine the depth of 109 intermediate-depth events using PcP phases and showed that their foci lied on an amphitheatrically-shaped Benioff zone, which dips from the outer arc (Hellenic Trench) towards the concave part of the Hellenic Arc. This has been confirmed by recent studies, showing that the subduction is separated in a shallower (20-100km), small-dip (-20-30°) section where the lithospheric coupling takes place and events up to M = 8.0 occur, and a deeper (100-180km) part with higher dipping angle (-45°) where events up to M=7.0 occur. Fault plane solutions which have been constructed since the 60s were used for the study of the active tectonics in the Aegean. Their use allowed the detection of reverse faulting along the Hellenic Arc (Papazachos and Delibasis 1969), the Rhodes sinistral fault (Papazachos 1961), as well as the domination of a strong ~N-S extension field throughout the whole back-arc Aegean area (McKenzie 1970, 1972, 1978). The identification of the dextral transform Cephalonia fault (Scordilis et al., 1985) was also of significant importance for the understanding of the Aegean tectonics. This understanding was enhanced by the results obtained about the geophysical lithospheric structure of the Aegean, using either traditional or tomographic methods. These results showed strong crustal thickness variations in agreement with isostasy, detected the presence of a high-velocity subducted slab under the Aegean, with low-velocity/low-Q material in the mantle wedge above the slab, as usually anticipated for a subduction zone. The active deformation of the Aegean has been studied by seismological, geodetic and palaeomagnetic methods. The obtained results allowed the determination of various models describing the active crustal deformation in the Aegean area, showing a anticlockwise motion for Anatolia and a fast southwestern motion of the Aegean microplate at an average rate of ~3.5cm/yr relative to Europe. Similar studies have been performed for the subducted slab. The derivation of such models is further supported by geophysical and geological studies that led to the identification and classification of a large number of active faults, which are related to several strong shallow events in the broader Aegean area. In general, active seismic faults in the Aegean area can be separated in ten main groups, which exhibit different type of faulting. The active deformation and faulting characteristics of the broader Aegean area is the base of the understanding of the driving mechanisms, which control the Aegean active tectonics. In general, the convergence of Africa and Eurasia is responsible for the eastern Mediterranean subduction under the Aegean. The Arabian plate pushes the Anatolia microplate towards the Aegean, thus affecting the active tectonic setting in the Northern Aegean where the dextral motion along the northern Anatolia border continues. Also, the Apulia (Adriatic) anticlockwise rotation results in convergence along the coastal Albania and NW Greece, with trust faulting. However, the main controlling force of the active tectonics in the Aegean is the fast southwest Aegean motion and its overriding of the Mediterranean lithosphère, which is responsible for the large thrust events along the Hellenic Arc, as well as for the large seismicity of the Cephalonia (dextral) and Rhodes (sinistral) faults that are the contact between the Aegean microplate and Apulia and the eastern Mediterranean (east of Rhodes) plates, respectively.
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Baird, Graham B. "Late Ottawan orogenic collapse of the Adirondacks in the Grenville province of New York State (USA): Integrated petrologic, geochronologic, and structural analysis of the Diana Complex in the southern Carthage-Colton mylonite zone." Geosphere 16, no. 3 (March 19, 2020): 844–74. http://dx.doi.org/10.1130/ges02155.1.
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Abstract Crustal-scale shear zones can be highly important but complicated orogenic structures, therefore they must be studied in detail along their entire length. The Carthage-Colton mylonite zone (CCMZ) is one such shear zone in the northwestern Adirondacks of northern New York State (USA), part of the Mesoproterozoic Grenville province. The southern CCMZ is contained within the Diana Complex, and geochemistry and U-Pb zircon geochronology demonstrate that the Diana Complex is expansive and collectively crystallized at 1164.3 ± 6.2 Ma. Major ductile structures within the CCMZ and Diana Complex include a northwest-dipping penetrative regional mylonitic foliation with north-trending lineation that bisects a conjugate set of mesoscale ductile shear zones. These ductile structures formed from the same 1060–1050 Ma pure shear transitioning to a top-to-the-SSE shearing event at ∼700 °C. Other important structures include a ductile fault and breccia zones. The ductile fault formed immediately following the major ductile structures, while the breccia zones may have formed at ca. 945 Ma in greenschist facies conditions. Two models can explain the studied structures and other regional observations. Model 1 postulates that the CCMZ is an Ottawan orogeny (1090–1035 Ma) thrust, which was later reactivated locally as a tectonic collapse structure. Model 2, the preferred model, postulates that the CCMZ initially formed as a subhorizontal mid-crustal mylonite zone during collapse of the Ottawan orogen. With continued collapse, a metamorphic core complex formed and the CCMZ was rotated into is current orientation and overprinted with other structures.
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Cohen, Wendy E., Richard D. Marshall, Allison C. Yacker, and Lance A. Zinman. "SEC sues asset managers for using untested, error-filled quantitative investment models." Journal of Investment Compliance 20, no. 1 (May 7, 2019): 44–46. http://dx.doi.org/10.1108/joic-01-2019-0004.
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Purpose To explain actions the US Securities and Exchange Commission (SEC) brought on August 27, 2018, against a group of affiliated investment advisers and broker-dealers for what the SEC considered misleading and insufficient representations and disclosures, insufficient compliance policies and procedures, and insufficient research and oversight concerning the use of faulty quantitative models to manage certain client accounts. Design/methodology/approach Explains the SEC’s findings concerning the advisers’ and broker-dealers’ failure to confirm that certain models worked as intended, to disclose the risks associated with the use of those models, to disclose the role of a research analyst in developing the models, to disclose the use of volatility overlays along with the associated risks, to determine whether a fund’s holdings were sufficient to support a consistent dividend payout without a return of capital, and to take sufficient steps to confirm the advertised performance of another investment manager whose products they were marketing. Provides insight into the SEC’s position and offers key takeaways. Findings These cases are significant for advisers who use quantitative models to implement their investment strategies in the management of client accounts and signal the SEC’s continued focus on investment advisers’ compliance with disclosure obligations to discretionary account investors. Practical implications Each manager should consider its own facts and circumstances, and should consult with counsel, in assessing how and to what extent to incorporate the SEC’s conclusions in crafting disclosure and other communications with investors on matters such as adequate representations, testing and validation of models, disclosure of errors, and verifying performance claims. Originality/value Practical guidance from experienced securities lawyers.
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Buys, Jonas, Vincenzo De Florio, and Chris Blondia. "Optimization of WS-BPEL Workflows through Business Process Re-Engineering Patterns." International Journal of Adaptive, Resilient and Autonomic Systems 1, no. 3 (July 2010): 25–41. http://dx.doi.org/10.4018/jaras.2010070102.
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With the advent of XML-based SOA, WS-BPEL swiftly became a widely accepted standard for modeling business processes. Although SOA is said to embrace the principle of business agility, BPEL process definitions are still manually crafted into their final executable version. While SOA has proven to be a giant leap forward in building flexible IT systems, this static BPEL workflow model should be enhanced to better sustain continual process evolution. In this paper, the authors discuss the potential for adding business intelligence with respect to business process re-engineering patterns to the system to allow for automatic business process optimization. Furthermore, the paper examines how these re-engineering patterns may be implemented, leveraging techniques that were applied successfully in computer science. Several practical examples illustrate the benefit of such adaptive process models. These preliminary findings indicate that techniques like the re-sequencing and parallelization of instructions, further optimized by introspection, as well as techniques for achieving software fault tolerance, are particularly valuable for optimizing business processes. Finally, the authors elaborate on the design of people-oriented business processes using common human-centric re-engineering patterns.
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Cascio, Michele, Ioannis Deretzis, Giuseppe Fisicaro, Giuseppe Falci, Giovanni Mannino, and Antonino Magna. "Tailoring Active Defect Centers During the Growth of Group IV Crystals†." Proceedings 12, no. 1 (December 19, 2019): 32. http://dx.doi.org/10.3390/proceedings2019012032.
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Defects, e.g., Vacancies (Vs) and Defect-impurity centers, e.g., Nitrogen-Vacancy complexes (NVs), in group IV materials (diamond, SiC, graphene) are unique systems for Quantum Technologies (QT). The control of their positioning is a key issue for any realistic QT application and their tailored inclusion during controlled crystal-growth processes could overcome the limitations of other incorporation methods (e.g., ion implantation causing strong lattice damage). To date, the atomistic evolution regarding the growth of group IV crystals is barely known and this missing knowledge often results in a lack of process control in terms of mesoscopic crystal quality, mainly concerning the eventual generation of local or extended defects and their space distribution. We have developed Kinetic Monte Carlo models to study the growth kinetics of materials characterized by sp 3 bonding symmetries with an atomic-level accuracy. The models can be also coupled to the continuum simulation of the gas-phase status generated in the equipment to estimate the deposition rate and reproduce a variety of growth techniques (e.g., Chemical and Physical Vapour deposition, sublimation, etc.). Evolution is characterized by nucleation and growth of ideal or defective structures and their balance depends critically on process-related parameters. Quantitative predictions of the process evolution can be obtained and readily compared with the structural characterization of the processed samples. In particular, we can describe the surface state of the crystal and the defect generation/evolution (for both point and extended defects, e.g., stacking faults) as a function of the initial substrate conditions and the process parameters (e.g., temperature, pressure, gas flow).
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Deichmann, Nicholas. "Far-field pulse shapes from circular sources with variable rupture velocities." Bulletin of the Seismological Society of America 87, no. 5 (October 1, 1997): 1288–96. http://dx.doi.org/10.1785/bssa0870051288.
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Abstract Recently, Sato (1994) developed a simple earthquake source model of a circular rupture expanding outward from the center of a fault with constant stress drop. In contrast to previous models, the rupture velocity is allowed to vary over the duration of faulting. This model is used to synthesize apparent moment-rate functions for a three-stage source process: first, the rupture starts out with a gradually increasing velocity, then, it continues to expand uniformly until, finally, it slows to a gradual stop. Synthetic velocity seismograms are obtained from a convolution of the apparent moment-rate functions with a causal Q-operator and an appropriate instrument response. Comparisons with an example of an earthquake signal show that, in the context of the proposed model, the observed emergent P-wave onset, which is not compatible with a constant rupture velocity, can be explained by a gradually accelerating rupture front. Systematic departures from the generally expected scaling relationship between seismic moment and rupture duration are often interpreted as evidence for a dependence of stress drop on seismic moment. However, the trade-off between stress drop and rupture velocity inherent in all kinematic source models implies that such deviations can just as well be attributed to systematic variations of rupture velocity. Whereas, in general, the total duration of the far-field displacement pulse is shorter for P waves than for S waves, the model predicts that the rise time, τ1/2, of the displacement pulse should be longer for P waves than for S waves. This feature could constitute a critical test of the model and also provide a constraint on the rupture velocity.
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Bray, Matthew, Jacob Utley, Yanuri Ning, Angela Dang, Jacquelyn Daves, Isabel White, Ahmed Alfataierge, et al. "Multidisciplinary analysis of hydraulic stimulation and production effects within the Niobrara and Codell reservoirs, Wattenberg Field, Colorado — Part 2: Analysis of hydraulic fracturing and production." Interpretation 9, no. 4 (July 12, 2021): SG13—SG29. http://dx.doi.org/10.1190/int-2020-0153.1.
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Enhanced hydrocarbon recovery is essential for continued economic development of unconventional reservoirs. We have focused on dynamic characterization of the Niobrara and Codell Formations in Wattenberg Field through the development and analysis of a full integrated reservoir model. We determine the effectiveness of the hydraulic fracturing and production with two seismic monitor surveys, surface microseismic, completion data, and production data. The two monitor surveys were recorded after stimulation and again after two years of production. Identification of reservoir deformation due to hydraulic fracturing and production improves reservoir models by mapping nonstimulated and nonproducing zones. Monitoring these time-variant changes improves the prediction capability of reservoir models, which in turn leads to improved well and stage placement. We quantify dynamic reservoir changes with time-lapse P-wave seismic data using prestack inversion and velocity-independent layer stripping for velocity and attenuation changes within the Niobrara and Codell reservoirs. A 3D geomechanical model and production data are history matched, and a simulation is run for two years of production. Results are integrated with time-lapse seismic data to illustrate the effects of hydraulic fracturing and production. Our analyses illustrate that chalk facies have significantly higher hydraulic fracture efficiency and production performance than marl facies. In addition, structural and hydraulic complexity associated with faults generate spatial variability in a well’s total production.
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Gorodnitskiy, A. M., A. N. Ivanenko, O. V. Levchenko, I. A. Veklich, and N. A. Shishkina. "DEEP STRUCTURE OF OSBORN PLATO (INDIAN OCEAN) ACCORDING TO MAGNETIC AND GRAVITY MODELING." Journal of Oceanological Research 48, no. 2 (August 28, 2020): 69–90. http://dx.doi.org/10.29006/1564-2291.jor-2020.48(2).5.
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According to the data of hydro-magnetic surveying and satellite altimetry, using the original technology for solving the inverse problem, 2D models of the magnetic layer for three latitudinal profiles crossing the submarine plateau of Osborne in the southern, central and northern parts were constructed. Density modeling for these three profiles was carried out using the available worldwide data on free air anomalies, reduced to the Bouguer anomaly. On all profiles, zones of increased effective magnetization with complex morphology are confidently distinguished. The distinguished sources of magnetic anomalies are tending toward two deep horizons. The upper one corresponds to layer 2 of the classical model of the magnetic layer of the oceanic lithosphere and is a source of local magnetic anomalies of both signs. The lower magnetic layer, the bottommost part of which approximately corresponds to the depth of the Moho surface according to density modeling, is apparently composed of serpentinites. The crust is broken by a system of sub-meridional faults, to which confined deep magnetic bodies, possibly associated with serpentinite protrusions. The revealed laterally inhomogeneous deep structure of the magnetic layer of the Osborne plateau and the adjacent NER segment testifies to their complex multi-stage volcano-tectonic evolution, which continues to present day.
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McBride, Sara K., Andrea L. Llenos, Morgan T. Page, and Nicholas van der Elst. "#EarthquakeAdvisory: Exploring Discourse between Government Officials, News Media, and Social Media during the 2016 Bombay Beach Swarm." Seismological Research Letters 91, no. 1 (November 6, 2019): 438–51. http://dx.doi.org/10.1785/0220190082.
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Abstract Communicating probabilities of natural hazards to varied audiences is a notoriously difficult task. Many of these challenges were encountered during the 2016 Bombay Beach, California, swarm of ~100 2≤M≤4.3 earthquakes, which began on 26 September 2016 and lasted for several days. The swarm’s proximity to the southern end of the San Andreas fault caused concern that a larger earthquake could be triggered. Within 1–2 days, different forecast models were used to evaluate the likelihood of a larger event with two agencies (the U.S. Geological Survey [USGS] and the California Governor’s Office of Emergency Services) releasing probabilities and forecasts for larger earthquakes. Our research explores communication and news media efforts, as well as how people on a microblogging social media site (Twitter) responded to these forecasts. Our findings suggest that news media used a combination of information sources, basing their articles on what they learned from social media, as well as using information provided by government agencies. As the swarm slowed down, there is evidence of the continued interplay between news media and social media, with the USGS issuing revised probability reports and scientists from the USGS and other institutions participating in media interviews. In reporting on the swarm, news media often used language more generally than the scientists; terms such as probability, likelihood, chance, and possibility were used interchangeably. Knowledge of how news media used scientific information from the 2016 Bombay Beach forecasts can assist local, state, and federal agencies in developing effective communication strategies to respond to future earthquakes.
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Cheng, Wai Kit, Ismail Mohd Khairuddin, Anwar P.P. Abdul Majeed, and Mohd Azraai Mohd Razman. "The Classification of Heart Murmurs: The Identification of Significant Time Domain Features." MEKATRONIKA 2, no. 2 (December 13, 2020): 36–43. http://dx.doi.org/10.15282/mekatronika.v2i2.6748.
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Phonocardiogram (PCG) is a type of acoustic signal collected from the heartbeat sound. PCG signals collected in the form of wave files and collected type of heart sound with a specific period. The difficulty of the binomial class in supervised machine learning is the steps-by-steps workflow. The consideration and decision make for every part are importantly stated so that misclassification will not occur. For the heart murmurs classification, data extraction has highly cared for it as we might have fault data consisting of outside signals. Before classifying murmurs in binomial, it will involve multiple features for selection that can have a better classification of the heart murmurs. Nevertheless, since classification performance is vital to conclude the results, models are needed to compare the research's output. The main objective of this study is to classify the signal of the murmur via time-domain based EEG signals. In this study, significant time-domain features were identified to determine the best features by using different feature selection methods. It continues with the classification with different models to compete for the highest accuracy as the performance for murmur classification. A set of Michigan Heart Sound and Murmur database (MHSDB) was provided by the University of Michigan Health System with chosen signals listening with the bell of the stethoscope at the apex area by left decubitus posture of the subjects. The PCG signals are pre-processed by segmentation of three seconds, downsampling eight thousand Hz and normalized to -1, +1. Features are extracted into ten features: Root Mean Square, Variance, Standard Deviation, Maximum, Minimum, Median, Skewness, Shape Factor, Kurtosis, and Mean. Two cross-validation methods applied, such as data splitting and k-fold cross-validation, were used to measure this study's data. Chi-Square and ANOVA technique practice to identify the significant features to improve the classification performance. The classification learners are enrolled and compared by Ada Boost, Random Forest (RF) and Support Vector Machine (SVM). The datasets will separate into a ratio of 70:30 and 80:20 for training and testing data, respectively. The chi-Square selection method was the best features selection method and 80:20 data splitting with better performance than the 70:30 ratio. The best classification accuracy for the models significantly come by SVM with all the categories with 100% except 70:30 test on test data with 97.2% only.
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Sinha, Supriya, Arthur Walmsley, Nigel Clegg, Brigido Vicuña, Hsu-Hsiang (Mark) Wu, Andrew McGill, Téo Paiva dos Reis, et al. "Past, Present, and Future Applications of Ultradeep Directional Resistivity Measurements: A Case History From the Norwegian Continental Shelf." Petrophysics – The SPWLA Journal of Formation Evaluation and Reservoir Description 63, no. 6 (December 1, 2022): 604–33. http://dx.doi.org/10.30632/pjv63n6-2022a3.
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With the introduction of ultradeep azimuthal resistivity (UDAR) logging-while-drilling (LWD) tools toward the beginning of the last decade, the oil and gas industry went from real-time mapping of formation boundaries a few meters from the wellbore to tens of meters away. This innovation allowed early identification of resistivity boundaries and promoted proactive geosteering, allowing for optimization of the wellbore position. Additionally, boundaries and secondary targets that may never be intersected are mapped, allowing for improved well planning for sidetracks, multilaterals, and future wells. Modern tool design and inversion algorithms allow mapping the reservoir in 3D and exploring the sensitivity of these tools to the electromagnetic field ahead of the measure point for look-ahead resistivity. Improvements in the technology over the past decade have changed the way wellbores are planned, drilled, and completed, and reservoir models are updated. This paper presents a case study summarizing the advances in UDAR measurements and inversions over the last decade. The case study presents the whole workflow from prejob planning, service design, and execution of one-dimensional (1D) and three-dimensional (3D) inversion in addition to the future potential of look ahead in horizontal wells. Prewell simulations provide a guide to expected real-time tool responses in highly heterogeneous formations. This identifies how far from the wellbore 1D inversions can map major boundaries above and below the well. A fault was expected toward the toe of the well, and UDAR was used as a safeguard to avoid exiting the reservoir. Standard 1D inversion approaches are too simplistic in this complex geologic setting. Thus, 3D inversion around the wellbore and ahead of the transmitter is also explored to demonstrate the improvements this understanding can bring regarding geostopping toward the fault and reservoir understanding in general. Successful geosteering requires personnel trained to handle complex scenarios. Geosteering training simulators (GTS) could be efficient tools for training to interpret inversions where the “truth” is known from realistic 3D model scenarios. The team can learn how to best exploit UDAR technology and inversion results within its limits and not extend the interpretation beyond acceptable uncertainty levels. It will also be addressed how the understanding of inversion uncertainty could be updated in real time in the future. The continued future success of UDAR technology and 1D to 3D inversion results for look-ahead and look-around applications will depend heavily on uncertainty management of the inversions to avoid wrong decisions and potentially reduced well economy.
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Gunnels, Michael, Gurban Yetrimishli, Sabina Kazimova, and Eric Sandvol. "Seismotectonic evidence for subduction beneath the Eastern Greater Caucasus." Geophysical Journal International 224, no. 3 (November 5, 2020): 1825–34. http://dx.doi.org/10.1093/gji/ggaa522.
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SUMMARY We generated high-resolution 3-D seismic velocity models as well as a relocated earthquake catalogue across the eastern Greater Caucasus and Kura basins. This work was done using data from the recently upgraded Republic Seismological Survey Center's (RSSC) seismic network. We generated our tomographic images of crustal velocity structure in Azerbaijan using double-difference inversions (i.e. tomoDD and hypoDD). Earthquake catalogues from the RSSC between 2011 and 2016 were used; these catalogues include absolute arrival times of 103 288 P- and 120 952 S-wave traveltime picks for 7574 events recorded at 35 stations in Azerbaijan. Beginning with a layered, 1-D velocity model that was estimated using VELEST, we inverted simultaneously for relative location, Vp and Vs on a 3-D grid with dimensions 670 × 445 × 45 km, with a uniform grid spacing of 55 × 55 × 5 km for all of Azerbaijan. We observe that the relocated hypocentres cluster into two depth ranges, at the surface and at depth, that appear to correspond to major fault zones and the top of a subducting plate. Additionally, we note intermediate depth seismicity (∼50–60 km) beneath the Kura Basin, and a northward deepening of earthquake depths. Seismic velocities vary significantly throughout the study region; we observe very slow velocities throughout the Kura Basin between 5 and 15 km, and elevated velocities at 20–35 km. The wholesale velocity structure and seismic structure of Kura Basin strongly mirrors that of the Caspian Sea, which suggests that the geodynamics of the Caspian continue westwards into Azerbaijan. The key results of this study suggest that the northward subduction observed in the Caspian Sea continues beneath the Eastern Greater Caucasus, as well as provides evidence for active faulting along the southern margin of the mountain range.
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Negri, O., and T. Abram. "INFLUENCE OF FUEL FLOW RATE VARIATION ON MOLTEN SALT REACTOR PERFORMANCE." EPJ Web of Conferences 247 (2021): 01008. http://dx.doi.org/10.1051/epjconf/202124701008.
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Molten Salt Reactors are Gen-IV reactors that use liquid fuel. Fluid fuel allows continuous removal of fission gases as well as batch fuel reprocessing. With these control mechanisms the system can be sustained within the desired operating temperature range and required power output. These methods rely on the presence of a chemical processing plant on-site that adds complexity. This also creates a risk of processing plant unavailability due to faults, emergency downtime or maintenance. The work considers variation of fuel salt flow rate in Molten Salt Reactors as a means of controlling reactor operation without using reprocessing. The analysis is performed using the Molten Salt Fast Reactor as an example. An extended version of the SERPENT Monte-Carlo transport code coupled with OpenFOAM generic platform were used for capturing delayed neutron drift, decay heat, gaseous fission product removal, calculating fuel salt velocity vectors and the fuel temperature distribution. The two models were coupled via a script that accounted for reactivity insertion between time steps and the changes caused in the fission power. Results confirm that, while operating at constant power, the difference between fuel inlet and outlet temperatures increase as the flow rate decreases. Burnup analysis has shown that while the average fuel temperature continues to reduce with time, the difference between inlet and outlet temperatures can be controlled by varying the flow rate while maintaining constant power. Finally, the variation in the fuel flow rate has been shown to extend the reactor operating time with no insertion of additional fissile inventory.
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Shahpasandzadeh, Majid, Hemin Koyi, and Faramarz Nilfouroushan. "The significance of switch in convergence direction in the Alborz Mountains, northern Iran: Insights from scaled analogue modeling." Interpretation 5, no. 1 (February 1, 2017): SD81—SD98. http://dx.doi.org/10.1190/int-2016-0117.1.
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The switch in direction of convergence between Central Iran and the Eurasian Plate is believed to have a significant impact on the structural style in the Alborz Mountains, in the north of Iran. To understand the deformation pattern and investigate the influence of the South Caspian Basin kinematics since the middle Miocene on the structural styles and active tectonics of the Alborz Mountains, a series of scaled analogue models were prepared, in which passively layered loose sand simulating the sedimentary units were subjected to orthogonal and subsequently oblique shortening by a rigid indenter. Model results indicate that during the shortening, an arcuate-shaped foreland-vergent imbricate stack forms in front of the indenter. The orthogonal shortening is characterized by a prevailing right-lateral and left-lateral oblique-slip motion in the east and west of the model, respectively. This shift in kinematics contradicts the proposed preneotectonic (orthogonal) model of the Alborz. However, during oblique shortening, model results show that deformation is mainly accommodated by left-lateral transpression within the sand wedge and internal deformation. Oblique shortening is consistently accommodated by continued left-lateral motion on the west-northwest-trending oblique thrusts, whereas the east–west-trending thrusts and the preexisting east-northeast-trending right-lateral oblique thrusts reactivate as left-lateral oblique faults. Precise monitoring of the model surface also illustrates partitioning of shortening into the foreland-vergent left-lateral thrusting in the south and hinterland-vergent back thrusting in the north. These model results are generally consistent with field observations and GPS data of structure and kinematics of the Alborz Mountains.
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Hicks-Bartlett, Alani Rosa. "Deceptive Art, Bad Education, and the Letter to Michetti: Classical Intertexts and Artistic Failure in D’Annunzio’s Il Piacere." Comparative Literature 71, no. 4 (December 1, 2019): 381–407. http://dx.doi.org/10.1215/00104124-7709591.
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Abstract Gabriele D’Annunzio’s Il Piacere (Pleasure) feints at being a bildungsroman. Even as it incorporates the genre’s defining tropes, it repeatedly undermines them, staging an educational process that is continually frustrated and problematized. Il Piacere can therefore be read as the story of a bad education, as it foregrounds an educational model that is upended before it even starts. More specifically, due to his faulty education, the novel’s protagonist sputters through the stages of his formation, failing to mature or develop appropriately. He founders in a crisis of representation as the fullness of creative, artistic, and amorous satisfaction continues to elude him. The objective of the bildungsroman thus stands as the elusive and problematic ideal to which Il Piacere’s protagonist should strive and remains a constant, tortured concern throughout the novel. D’Annunzio prefigures this impasse in his overlooked dedicatory letter, which recalls and subverts traditional models of formation. The letter uses a Catullan intertext to emphasize and model the importance of instruction and guidance to growth and artistic maturation. By understanding the portrayal of education in the dedicatory letter and the novel, readers learn that the structures that might have upheld the bildungsroman’s implicit promise are in short supply. The same dynamic is reiterated through classical topoi like the stories of Pygmalion and Zeuxis. These artistically grounded intertexts anticipate the major concerns of Il Piacere’s protagonist: how to engage with beauty and art to obtain pleasure, and how to overcome an improper orientation to reach amorous, artistic, and authorial objectives.
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Giuliani, Gaston, Lee A. Groat, Dan Marshall, Anthony E. Fallick, and Yannick Branquet. "Emerald Deposits: A Review and Enhanced Classification." Minerals 9, no. 2 (February 13, 2019): 105. http://dx.doi.org/10.3390/min9020105.
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Although emerald deposits are relatively rare, they can be formed in several different, butspecific geologic settings and the classification systems and models currently used to describeemerald precipitation and predict its occurrence are too restrictive, leading to confusion as to theexact mode of formation for some emerald deposits. Generally speaking, emerald is beryl withsufficient concentrations of the chromophores, chromium and vanadium, to result in green andsometimes bluish green or yellowish green crystals. The limiting factor in the formation of emeraldis geological conditions resulting in an environment rich in both beryllium and chromium orvanadium. Historically, emerald deposits have been classified into three broad types. The first andmost abundant deposit type, in terms of production, is the desilicated pegmatite related type thatformed via the interaction of metasomatic fluids with beryllium-rich pegmatites, or similar graniticbodies, that intruded into chromium- or vanadium-rich rocks, such as ultramafic and volcanic rocks,or shales derived from those rocks. A second deposit type, accounting for most of the emerald ofgem quality, is the sedimentary type, which generally involves the interaction, along faults andfractures, of upper level crustal brines rich in Be from evaporite interaction with shales and otherCr- and/or V-bearing sedimentary rocks. The third, and comparatively most rare, deposit type is themetamorphic-metasomatic deposit. In this deposit model, deeper crustal fluids circulate along faultsor shear zones and interact with metamorphosed shales, carbonates, and ultramafic rocks, and Beand Cr (±V) may either be transported to the deposition site via the fluids or already be present inthe host metamorphic rocks intersected by the faults or shear zones. All three emerald depositmodels require some level of tectonic activity and often continued tectonic activity can result in themetamorphism of an existing sedimentary or magmatic type deposit. In the extreme, at deepercrustal levels, high-grade metamorphism can result in the partial melting of metamorphic rocks,blurring the distinction between metamorphic and magmatic deposit types. In the present paper,we propose an enhanced classification for emerald deposits based on the geological environment,i.e., magmatic or metamorphic; host-rocks type, i.e., mafic-ultramafic rocks, sedimentary rocks, andgranitoids; degree of metamorphism; styles of minerlization, i.e., veins, pods, metasomatites, shearzone; type of fluids and their temperature, pressure, composition. The new classification accountsfor multi-stage formation of the deposits and ages of formation, as well as probable remobilizationof previous beryllium mineralization, such as pegmatite intrusions in mafic-ultramafic rocks. Suchnew considerations use the concept of genetic models based on studies employing chemical,geochemical, radiogenic, and stable isotope, and fluid and solid inclusion fingerprints. The emerald occurrences and deposits are classified into two main types: (Type I) Tectonic magmatic-relatedwith sub-types hosted in: (IA) Mafic-ultramafic rocks (Brazil, Zambia, Russia, and others); (IB)Sedimentary rocks (China, Canada, Norway, Kazakhstan, Australia); (IC) Granitic rocks (Nigeria).(Type II) Tectonic metamorphic-related with sub-types hosted in: (IIA) Mafic-ultramafic rocks(Brazil, Austria); (IIB) Sedimentary rocks-black shale (Colombia, Canada, USA); (IIC) Metamorphicrocks (China, Afghanistan, USA); (IID) Metamorphosed and remobilized either type I deposits orhidden granitic intrusion-related (Austria, Egypt, Australia, Pakistan), and some unclassifieddeposits.
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Gavel, Michelle M., Jeffrey M. Amato, Jason W. Ricketts, Shari Kelley, Julian M. Biddle, and Rafael A. Delfin. "Thermochronological transect across the Basin and Range/Rio Grande rift transition: Contrasting cooling histories in contiguous extensional provinces." Geosphere 17, no. 6 (October 12, 2021): 1807–39. http://dx.doi.org/10.1130/ges02381.1.
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Abstract The Basin and Range and Rio Grande rift (RGR) are regions of crustal extension in southwestern North America that developed after Laramide-age shortening, but it has not been clear whether onset and duration of extension in these contiguous extensional provinces were the same. We conducted a study of exhumation of fault blocks along a transect from the southeastern Basin and Range to across the RGR in southern New Mexico. A suite of 128 apatite and 63 zircon (U-Th)/He dates (AHe and ZHe), as well as 27 apatite fission-track (AFT) dates, was collected to investigate the cooling and exhumation histories of this region. Collectively, AHe dates range from 3 to 46 Ma, ZHe dates range from 2 to 288 Ma, and AFT dates range from 10 to 34 Ma with average track lengths of 10.8–14.1 µm. First-order spatiotemporal trends in the combined data set suggest that Basin and Range extension was either contemporaneous with Eocene–Oligocene Mogollon-Datil volcanism or occurred before volcanism ended ca. 28 Ma, as shown by trends in ZHe data that suggest reheating to above 240 °C at that time. AHe and ZHe dates from the southern RGR represent a wider range in dates that suggest the main phase of cooling occurred after 25 Ma, and these blocks were not reheated after exhumation. Time-temperature models created by combining AHe, AFT, and ZHe data in the modeling software HeFTy were used to interpret patterns in cooling rate across the study area and further constrain magmatic and/or volcanic versus faulting related cooling. The Chiricahua Mountains and Burro Mountains have an onset of rapid extension, defined as cooling rates in excess of >15 °C/m.y., at ca. 29–17 Ma. In the Cookes Range, a period of rapid extension occurred at ca. 19–7 Ma. In the San Andres Mountains, Franklin Mountains, Caballo Mountains, and Fra Cristobal range, rapid extension occurred from ca. 23 to 9 Ma. Measured average track lengths are longer in Rio Grande rift samples, and ZHe dates of >40 Ma are mostly present east of the Cookes Range, suggesting different levels of exhumation for the zircon partial retention zone and the AFT partial annealing zone. The main phase of fault-block uplift in the southern RGR occurred ca. 25–7 Ma, similar to what has been documented in the northern and central sections of the rift. Although rapid cooling occurred throughout southern New Mexico, thermochronological data from this study with magmatic and volcanic ages suggest rapid cooling was coeval with magmatism in the Basin and Range, whereas in the Rio Grande rift cooling occurred during an amagmatic gap. These observations support a model where an early phase of extension was facilitated by widespread ignimbrite magmatism in the southeastern Basin and Range, whereas in the southern Rio Grande rift, extension started later and continues today and may have occurred between local episodes of basaltic magmatism. These differences in cooling history make the Rio Grande rift tectonically distinct from the Basin and Range. We infer based on geologic and thermochronological evidence that the onset of extension in the southern Rio Grande rift occurred at ca. 27–25 Ma, significantly later than earlier estimates of ca. 35 Ma.
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Masihi, Mohsen, Peter R. King, and Peyman R. Nurafza. "Connectivity Prediction in Fractured Reservoirs With Variable Fracture Size: Analysis and Validation." SPE Journal 13, no. 01 (March 1, 2008): 88–98. http://dx.doi.org/10.2118/100229-pa.
Full textAbstract:
Summary Uncertainty in geometrical properties of fractures, when they are considered as the conductive paths for flow movement, affects all aspects of flow in fractured reservoirs. The connectivity of fractures, embedded in low-permeability zones, can control fluid movement and influence field performance. This can be analyzed using percolation theory. This approach uses the hypothesis that the permeability map can be split into either permeable (i.e., fracture) or impermeable (i.e., matrix) portions and assumes that the connectivity of fractures controls the flow. The analysis of the connectivity based on finite-size scaling assumes that fractures all have the same sizes. However, natural fracture networks involve a relatively wide range of fracture lengths, modeled by either scale-limited laws (e.g., log normal) or power laws. In this paper, we extend the applicability of the percolation approach to a system with a distribution of size. For scale-limited distributions, we use the hypothesis seen in the literature that the connectivity of fractures of variable size is identical to the connectivity of fractures of the same size whose length is given by an appropriate effective length. It is then necessary to define the percolation probability based on the excluded area arguments. In this research work, we also validate the applicability of this idea to fracture networks having a uniform, Gaussian, exponential, and log-normal length distribution. However, in the case of the power-law length distribution, we have found that the scaling parameters (e.g., correlation length exponent) have to be modified. The main contribution is to show how the critical exponents vary as a function of the power-law exponent. To validate the approach, we used outcrop data of mineralized fractures (vein sets) exposed on the southern margin of the Bristol Channel basin. We show that the predictions from the percolation approach are in good agreement with the results calculated from field data with the advantage that they can be obtained very quickly. As a result, they may be used for practical engineering purposes and may aid decision-making for real field problem. Introduction Many hydrocarbon reservoirs are naturally fractured. The conventional approach to investigate the impact of geological uncertainties on reservoir performance is to build a detailed reservoir model using available geophysical and geological data, upscale it, and then perform flow simulation. In fractured reservoirs, this can be done by using equivalent continuum models (i.e., dual porosity), discrete network models, or a combination of both [see Warren and Root (1963), Quenes and Hartley (2000), and Dershowitz et al. (2000)]. The nature of fluid flow in fractured reservoirs of low matrix permeability depends strongly on the spatial distribution of the conductive natural fractures. We use the term "fracture" to mean any discontinuity within a rock mass that developed as a response to stress. Fractures exist on various length scales from microns to kilometres. They appear as tensile (e.g., joints or veins) or shear (e.g., faults) and can act as hydraulic conductors or barriers to flow movement. Conductive fractures may be connected in a complicated manner to form a complex network. The connectivity of such networks is a crucial parameter in controlling flow movement, which in turn depends on the geometrical properties of the network such as fracture orientation, spacing, or length distribution.