Fault Structures Research Articles

Fault diagnosis of rotating machinery via multi-structure fusion discriminative projection

Rotating machinery is one of the important parts of industrial production equipment, and it is of great practical significance for fault diagnosis. Aiming at the problem of classification difficulty caused by feature interleaving in complex working conditions and high-dimension of rotating machinery fault samples, a rotating machinery fault diagnosis method based on multi-structure fusion discriminative projection (MFDP) is proposed. MFDP constructed intraclass and interclass hypergraph structures with multivariate relationships, fully revealing the higher-order association information among multiple samples. Besides, a tangential graph structure of MFDP is further constructed by combining the tangential affine of local samples to preserve the local tangential information of the manifold space. In the method, a unified objective optimization model of the discriminative hypergraph structures and local tangential graph structures is developed, and by solving the model, we can obtain fault structure features with well intraclass compactness and interclass separability. Extensive experiments on the Case Western Reserve University bearing dataset and Connecticut gear dataset show that the method has a good diagnostic accuracy of rotating machinery in different working conditions.

Reconciling onshore and offshore geological mapping: lessons from north Cornwall, SW England

Abstract We present the first detailed stratigraphic and structural geological map of offshore north Cornwall and Devon, SW England, based on freely available bathymetric data. Although the bathymetry is often spectacular, revealing fold and fault structures exposed on the seabed at a range of scales and with high resolution, interpretation is not as straightforward as it might appear and depends critically upon both accuracy and knowledge of the onshore geology. Unfortunately, onshore stratigraphic controls are limited and restricted to several thin ‘named shales’ whose coastal outcrops are not always well constrained. In addition, the structure is markedly non-cylindrical on local to regional scales, making seaward projection problematic, while the impact of early thrusting on the stratigraphy has often been previously neglected. We therefore developed a workflow to handle the problems we encountered, including: recognition of vertical to horizontal and 3D to 2D projections; variations in bathymetric data characteristics; prediction of expected seabed outcrop geometries based on coastal structures; incorporation of non-cylindrical effects; and problems with quantitative GIS terrain profiles and structural measurements that result in an absence of such measurements. The geological map produced should therefore be viewed as a step forward, but as forming a base for further detailed bathymetric mapping.

Fault Identification of U-Net Based on Enhanced Feature Fusion and Attention Mechanism

Accurate fault identification is essential for geological interpretation and reservoir exploitation. However, the unclear and noisy composition of seismic data makes it difficult to identify the complete fault structure using conventional methods. Thus, we have developed an attentional U-shaped network (EAResU-net) based on enhanced feature fusion for automated end-to-end fault interpretation of 3D seismic data. EAResU-net uses an enhanced feature fusion mechanism to reduce the semantic gap between the encoder and decoder and improve the representation of fault features in combination with residual structures. In addition, EAResU-net introduces an attention mechanism, which effectively suppresses seismic data noise and improves model accuracy. The experimental results on synthetic and field data demonstrate that, compared with traditional deep learning methods for fault detection, our EAResU-net can achieve more accurate and continuous fault recognition results.

Risk Assessment and Water Inrush Mechanism Study of Through-Type Fault Zone Based on Grey Correlation Degree

In order to effectively prevent and control the problem of water inrush from the through-type fault floor, based on the analysis of the case data of water inrush from the fault structure in the Fengfeng mining area, the types of karst water inrush from the floor are divided into 3 categories, 6 subcategories, and 17 fine categories. Four water inrush modes are summarized: composite structure water inrush, through-type fault water inrush, roof crack expansion water inrush, and floor vertical crack expansion water inrush. Based on the grey correlation theory and combined with the Analytic Hierarchy Process (AHP), this paper evaluates the water inrush risk of the F55-1 through-type fault zone from a micro individual perspective, taking the Xin’an Mine as the engineering background. Based on the water–rock coupling theory, the FLAC3D numerical simulation software is applied to study the disaster mechanism of the water inrush mode of the through-type fault. Through analyzing the changes of primary fracture stress and displacement of the intact floor strata and the aquifuge, and the pressure changes of confined water in fault zones, the collaborative water inrush mechanism of the damage and fracture of the bottom plate rock layer, the expansion and connection of the original fracture, and the seepage and progressive intrusion of the pressure water during the advancing process of the working face is analyzed. The research results indicate that the evaluation result of the water inrush risk of the F55-1 through-type fault in Xin’an Mine is Level I, belonging to the high risk and consistent with the actual situation model, verifying the rationality of the evaluation model. The process of water inrush in the numerical model is summarized as follows: a rock pressure failure zone is caused by the rupture and instability of floor aquifuge; a progressive intrusion zone develops—water inrush is connected between rock pressure failure zone and progressive intrusion zone; floor lagging flood occurs. Under the combined action of mine pressure and confined water pressure, the progressive intrusion height of confined water is significantly increased. The research results have important reference basis for future coal mining planning. This provides engineering reference and practical experience for the prevention and control of water damage in structured bottom plates under similar conditions.

A practical framework for performance-based reliability analysis of subway stations based on a fault–structure combined system

It is necessary to pay particular attention to the uncertainties that exist in an engineering problem to reduce the risk of seismic damage of infrastructures against natural hazards. Moreover, certain structural performance levels should be satisfied during strong earthquakes. However, these performance levels have been only well described for aboveground structures. This study investigates the main uncertainties involved in the performance-based seismic analysis of a multi-story subway station. More than 100 pulse-like and no pulse-like ground motions have been selected. In this regard, an effective framework is presented, based on a set of nonlinear static and dynamic analyses performed by OpenSees code. The probabilistic seismic demand models for computing the free-field shear strain of soil and racking ratio of structure are proposed. These models result in less variability compared with existing relations, and make it possible to evaluate a wider range of uncertainties through reliability analysis in Rtx software using the Monte Carlo sampling method. This work is performed for three different structural performance levels (denoted as PL1–PL3). It is demonstrated that the error terms related to the magnitude and location of earthquake excitations and also the corresponding attenuation relationships have been the most important parameters. Therefore, using a fault–structure model would be inevitable for the reliability analysis of subway stations. It is found that the higher performance level (i.e. PL3) has more sensitivity to random variables than the others. In this condition, the pulse-like ground motions have a major contribution to the vulnerability of subway stations.

A Fault-Tolerant Soft Swallowing Robot Capable of Grasping Delicate Structures Underwater

To improve the manipulation efficiency and robustness of soft grippers, this work proposes a soft swallowing robot with a continuous grasping mode. The soft swallowing robot has two advantages of grasping fault tolerance and structural fault tolerance: i) It can perform the grasping action uninterruptedly to deal with non-cooperative objects efficiently, unlike most existing grippers, which must perform the release action after grasping failure to carry out the next grasping action; ii) It can still maintain the grasping function after the failure of a part of its core structures. The finite element model quantitatively characterizes the effects of object size, friction coefficient, and manufacturing materials on the swallowing force. The fault tolerance experiments prove that the maximum proportion of structural faults that the soft swallowing robot can tolerate is 50%. In addition, the grasping experiments for underwater animals demonstrated that the soft swallowing robot has the advantages of high efficiency and strong adaptability in the manipulation of delicate structures. The research results are expected to be applied to underwater biological sample collection and seafood fishing.

Automatic carrier landing for UAV based on integrated disturbance observer and fault-tolerant control

PurposeAccurate glide path tracking is vital to the automatic carrier landing task of unmanned aerial vehicle (UAV). The purpose of this paper is to develop a reliable flight controller that can simultaneously deal with external disturbance, structure fault and actuator fault.Design/methodology/approachThe automatic carrier landing task is resolved into the glide path tracking problem and attitude tracking problem. The disturbance observer-based adaptive sliding mode control scheme is proposed for system stabilization, disturbance rejection and fault tolerance.FindingsBoth the Lyapunov method and exemplary simulations can prove that the disturbance estimation error and the attitude tracking error converge in finite time in the presence of external disturbances and various faults.Practical implicationsThe presented algorithm is testified by a UAV automatic carrier landing simulation, which shows the potential of practical usage.Originality/valueThe barrier function is introduced to adaptively update both the sliding mode observer gain and sliding mode controller gain, so that the sliding mode surface could converge to a predefined region without overestimation. The proposed flight controller ensures a secure carrier landing task.

Fault structure and segmentation of the Punta Montalva Fault in southwestern Puerto Rico using high-resolution digital elevation models

The Punta Montalva Fault is an active fault that slipped during the 2019–2023 Puerto Rico seismic sequence. It lies in southwestern Puerto Rico within the ∼250-km-wide deformation zone of the North American-Caribbean plate boundary. The fault cuts Miocene limestone and contains surface features that suggest left-lateral displacement. Previous work suggested that the fault connects with the North Boquerón Bay Fault for a length of 33 km and poses a large seismic hazard. However, not much is known about the structure, segmentation, and spatial extent of the fault as it is obscured under thick vegetation. This study used high-resolution topographic data to map the structure, segmentation, and spatial extent of the fault. The results would allow us to better assess the seismic potential of the Punta Montalva Fault by constraining its spatial extent and how strain has been accommodated. A 0.5 m resolution bare-earth digital elevation model (DEM) derived from a 2018 airborne LiDAR survey and another 1 m resolution 2018 DEM showing shallow bathymetry were used to map the Punta Montalva Fault. High-resolution mapping revealed that the Punta Montalva Fault is comprised of three main fault segments on land, a possible additional scarp, and three fault scarps on the seafloor to the SE. No evidence suggests the Punta Montalva Fault extends further NW of Punta Montalva into La Parguera in Lajas. The DEM revealed that the fault cuts a shallowly dipping sedimentary sequence of the Ponce Limestone that has karst topography in places. On land, the fault is conspicuous where it forms scarps, drags and cuts sedimentary layers, and forms a duplex structure with a predominantly left-lateral offset. A left-lateral offset of an intermittent stream has been refined to 133.6 ± 7.3 m. The fault scarps along a marine shelf strike E-W and show a maximum normal offset of 4.8 m. Another sub-parallel fault scarp in the seafloor strikes NW-SE and displays a left-lateral offset of 98.3 m. The total length of the fault segments is ∼2.67 km long. The surface segmentation suggests that the fault would have a lower seismic hazard than if it were continuous and connected to the North Boquerón Bay Fault. However, if the Punta Montalva Fault is continuous beneath the surface, its total fault length would be approximately 7.97 km long and would pose a larger seismic hazard than that suggested by the surface segmentation. Strike-slip, folding, and normal offset suggest that the area is being deformed by transtentional deformation, which supports seismic analyses and tectonic models.

The northeastern Algeria hydrothermal system: gravimetric data and structural implication

The Tell Atlas of Algeria has a huge potential for hydrothermal energy from over 240 thermal springs with temperatures up to 98^circ C in the Guelma area. The most exciting region is situated in the northeastern part which is known to have the hottest hydrothermal systems. In this work, we use a high-resolution gravity study to identify the location and origin of the hot water, and how it reaches the surface. Gravimetric data analysis shows the shapes of the anomalies arising due to structures at different subsurface depths. The calculation of the energy spectrum for the data also showcases the depths of the bodies causing anomalies. 3D-Euler deconvolution is applied to estimate the depths of preexisting tectonic structures (faults). These preprocessing steps assist with assessing signal attenuation that impacts the Bouguer anomaly map. The residual anomaly is used in a three-dimensional inversion to provide a subsurface density distribution model that illustrates the locations of the origin of the dominant subsurface thermal systems. Overall, the combination of these standard processing steps applied to the measurements of gravity data at the surface provides new insights about the sources of the hydrothermal systems in the Hammam Debagh and Hammam Ouled Ali regions. Faults that are key to the water infiltrating from depth to the surface are also identified. These represent the pathway of the hot water in the study area.

CURRENT STATUS AND WAYS TO IMPROVE THE EFFICIENCY OF THE DEVELOPMENT OF "KALMAZ" UNDERGROUND GAS STORAGE FACILITIES (UGSF)

Geological structure of the "Kalmaz" oil and gas field, that is being studied since 1930, is located 100 km south-west of Baku, in the north-eastern part of the lower Kura depression. Information on geological structure, stratigraphy, tectonics, oil and gas content of the field etc. has been collected as a result of the search and exploration works carried out and structural and research wells drilled. The "Kalmaz" field was formed from the brachianticlinal fold with south-east direction from north-west. The structure is divided into separate blocks by tectonic faults, and the blocks are not interconnected. Data on stratigraphic affiliation, lithology and thickness of stratigraphic units of sediments participating in the geological section of the site were obtained on the basis of deep wells drilled here. Upper Miocene-Pont, Pliocene and Quaternary sediments are involved in the geological section of the site. Tectonically, Kalmaz brachianticlinal is located in the north-eastern part of the lower Kura depression, over the Kalameddin-Bandovan anticline zone, between Mishovdag in the West and Khidirli folding in the East. The Kalmaz structure is mainly stretched in the north-west – south-east direction, however in the western part the axis of elongation of the structure takes a close direction to the latitude circle. The structure is asymmetrical. North-east wing is upright (lying angle is 35-400) and short, the south-west wing is relatively low-leaved (22-300) and being extensive passes to the south-east Shirvan syncline. The geological aspects of the structure was complicated by a fault that cuts its elongation at a certain angle. In the western part, tectonic fault passes through the north-east wing of the structure and through the south-west wing in the eastern part. As a result of the change in the direction of the axis of the fault structure, which is being talked about, cuts off the north-eastern wing in the western part, almost perpendicular to its lengthway and passes to the neighboring Navahi syncline. As a result of the fracture, the north-eastern wing of the Kalmaz structure and the south-western pericline were broken and dropped due to other parts of the fold. It's worth to note, that the Kalmaz structure has a very complex structure. This is also denoted by the Kalmaz mud volcano located in the central part of the fold. Despite the study of the geological aspects of the site by various methods and the numerous wells drilled here, its deep tectonics and connection with neighboring Mishovdagh and Khidirli structures have not been sufficiently studied. Numerous natural oil and gas manifestations are found in the site due to mud volcano springs. The mud volcano, located in the arch part of the fold, is related to a disruption that cuts its north-east wing. There is an active oil and gas flow from the mud springs arranged on a line in the direction of this disruption. Gas discharge related to Absheron sediments was detected in the structural mapping wells No. 39, 40, 41, 42, 44, 46 drilled on this strip. In most of these wells, the gas discharge passed into the gas fountain and lasted for a long time. 40000 m3/day gas and oil was obtained from the bottom Absheron sediments in the search well No. 87/2 located in the research site. In the well No. 15, drilled in a tectonic block in the south-eastern part of the fold, oil with a daily output of 38-39 t was obtained from the IV horizon of the productive layer (PL). Gas with daily production of 22 200 thousand m3 was obtained from the upper horizon of the PL in the search and operation well No. 22, and of 180 thousand m3 was obtained from the IV horizon of the PL in the well No. 40. As a result of research and exploration drilling, the I, II, III, IV, V, VI horizons of Kalmaz site have been proven to contain oil and gas. These facts show that the Kalmaz site has great oil and gas prospects. It should be noted that the presence of rich oil and gas underground gas storage facilitiess in the not yet opened and insufficiently studied lower horizons of the productive layer is beyond doubt. For this reason, information on geological study, stratigraphy, oil and gas characteristics, development, well fund of Kalmaz field, the first underground gas storage facilities in Azerbaijan, was analyzed in the article and due to the fact that a number of problems arose during the joint exploitation of wells, it was proposed to develop the well by dividing it into horizons. Keywords: gas, underground gas storage facilities, horizon, well, gas injection.

Reliability Analysis of High-Voltage Drive Motor Systems in Terms of the Polymorphic Bayesian Network

The reliability of the high-voltage drive motor system for pure electric commercial vehicles is in premium demand. Conventional reliability based on fault tree analysis methods is not suitable for the quantitative assessment of polymorphic systems. As an example of a pure electric commercial vehicle, this paper combines polymorphic theory and Bayesian theory to establish a polymorphic Bayesian network model of a high-voltage drive motor system in terms of a polymorphic fault tree and to quantitatively judge the system. The polymorphic Bayesian network (BN) model can accurately depict the high-voltage drive motor system’s miscellaneous fault states and solve the top event’s probability in every state, also solving the system and drawing the consistent conclusion that the presence of abrasive particles, high-temperature gluing, moisture, and localized high temperatures are the system’s weak links by solving the critical importance, probabilistic importance, and posterior probability of the underlying event, which provides a theoretical reference for structure contrive optimization and fault diagnosis. This is extremely important in terms of improving pure electric commercial vehicles’ high-voltage drive motor systems.

Exploratory Mapping of the Geothermal Anomalies in the Neoproterozoic Arabian Shield, Saudi Arabia, Using Magnetic Data

In this paper, certain areas of the Kingdom of Saudi Arabia (KSA) are assessed in order to map potential geothermal energy zones. To evaluate high-resolution aerial magnetic data, spectral depth analysis using a modified centroid approach was used. The calculated geothermal parameters were gridded in order to delineate the regions characterised by a shallow Curie point depth (CPD) and a high geothermal gradient (GG) as well as a high heat flow (HF). The CPD, GG and HF calculated from the analysed data varied in the ranges of 6.0–15.0 km, 40.0–100.0 °C/km and 90.0–270.0 mW/m2, respectively. The obtained results show the concurrence of the positions of shallow CPD (<8.0 km), high GG (>83.5 °C/km) and high HF (>211.0 mW/m2). The geothermal systems that are oriented in the E–W direction are related to the Red Sea tectonics, the tectonic opening of the Red Sea/Gulf of the Suez Rift, hot subterranean anomalies and high enthalpy from radioactive granites. Likewise, the geologic structures (fractures and faults) related to the Red Sea tectonics serve as channels for the movement of hydrothermal fluids and the deposition of associated minerals. All in all, another geophysical study involving deep boreholes, and seismic, magnetotelluric, electromagnetic and geochemical data should be conducted to evaluate and estimate precisely the economic reserves of geothermal resources.

Accumulation conditions and patterns of natural gas hydrate in the Muli permafrost area, northeastern margin of the Qinghai‒Tibet Plateau, NW China

Abstract The Muli permafrost area is the only midlatitude permafrost area where natural gas hydrates (NGHs) have been drilled. Although a series of achievements has been made in studies on NGH accumulation conditions in the permafrost area, related studies on gas hydrate stability zones, gas sources and groundwater are still controversial and need further work. Based on geophysical, geological and geochemical data, this paper systematically elaborates the main NGH accumulation conditions in the Muli area in terms of the pressure‒temperature stability conditions, fault structure, gas composition, gas source, reservoir characteristics, groundwater distribution and topographic characteristics. The results show that the thicknesses of the NGH stability zone range from 491.0 to 962.7 m. The fault structure can provide a pathway for hydrocarbon gas migration from deep to NGH stability zones, in which thrust faults can prevent the upwards migration of gas by sealing it below the hanging wall block. Rock fractures in the NGH stability zone can not only be gas migration channels, but also serve as a reservoir space for NGH accumulation. The hydrocarbon gas of NGHs shows multiple origins and is mainly composed of oil-associated gas. The formation of frost mounds related to the overpressured gas ejection caused by NGH decomposition may imply the existence of NGHs. Synthetically, similarities and differences in NGH accumulation conditions between the Muli permafrost area and other high-latitude permafrost areas are proposed, and the ‘regression’ NGH accumulation pattern in the Muli area is constructed. The study results can enrich theoretical knowledge of terrestrial NGH accumulation, and provide scientific guidance for NGH exploration in midlatitude permafrost areas.

Role of Integrated Magnetics and Geology in Tracking and Exploring Complex Structures Controlling Gold Mineralization. Example from the Fawakheir-Atalla Gold Prospects, Eastern Desert, Egypt

Gold mineralisation is spatially and chronologically correlated with fault/shear zones in many of the world-class gold mines. Hence, the indirect exploration for Au mineralisation is linked with shearing and complex structures in many areas. Hence, in general, the need for a rapid, effective and new technology for gold exploration that reflects the structure set-up, shear zones, faults and related structural elements is crucial in the gold industry. In this article, we present an example of an integrated approach to gold exploration in the Fawakheir-Attala gold mining prospect in the eastern desert of Egypt. Remote sensing is used to test for rock differentiation; intensive field geological investigations were conducted along several traverses. Petrographic and geochemical analysis of selected samples confirmed Au content in some localities. Moreover, magnetic methods are used extensively (either aeromagnetic or measured land profiles) to investigate the magnetic signature of the different reported rock units and their relationship with gold occurrences and deposits. Normalised source strength transformation, magnitude magnetic transforms and subsurface modelling are used to explore the inherent relation between the surface and subsurface magnetic susceptibilities. The magnetic signature of the talc-carbonate rocks is determined. The gradational contact against the serpentinite is explained. Because three current Au mines are associated with contacts/fractures, the clear relation between the contacts/fractures and the magnetic data and the comparison with the contact occurrence density COD (heat) magnetic filtered map, the present analysis workflow can now be used to suggest new locations for Au occurrences.

Structural Fault Diagnosis Based on Static and Dynamic Response Parameters

Structural fault diagnosis is an important subject for ensuring the normal use of structures. More test data will help to improve the accuracy and reliability of structural fault diagnosis. Therefore, a structural fault detection algorithm based on static–dynamic mixed sensitivity analysis is proposed. The vibration parameters used were the vibration modes of some of the nodes in the structure measured by the vibration test system. The static response parameter used was the vertical displacement of the structure under the gravity load measured by the static test system. In particular, the gravity load and the structure were connected rigidly to form a new added-mass system. The vibration mode of the additional-mass system was measured again to obtain more equations for fault evaluation. Based on the static and dynamic measurement data, the failure coefficients of all components in the structure were calculated through the mixed sensitivity of the static displacement and vibration-mode shape. According to the calculated value of the failure coefficient, the failure state of all components in the structure could be finally evaluated. The main innovation of the proposed method was the use of the static load as a part of the new added-mass system to obtain more vibration parameters for the defect diagnosis. The implementation process and effect of this method were verified using a numerical truss structure and an experimental steel beam structure. Moreover, the defect diagnosis results of the proposed hybrid method were compared with those of a pure static algorithm and a pure dynamic algorithm to illustrate the advantages of the hybrid method. The research results showed that this method has the advantages of simple implementation and high diagnosis accuracy. Especially for symmetric structures, the proposed method can successfully avoid the possible missed diagnoses of the pure static algorithm and pure dynamic method. The algorithm provides a simple and feasible method for structural defect identification.

Study on Failure Mechanism of Roadway Surrounding Rock and Hierarchical Continuous Support Technology in Unidirectional Fault Area

A fault is a common geological structure in coal mining. Large deformation or even instability and collapse often occur in roadways in fault areas, which restricts the safe and efficient production of mines. With the track roadway of the 5206 working face of Xin’an Coal Mine as the engineering background, this study aims to explore the failure mechanism of surrounding rock under the influence of fault structures. Field investigation and numerical simulation were used comprehensively to analyze the failure characteristics of the surrounding rock under the influence of a unidirectional fault structure. Based on the principle of thick-layer transboundary anchorage, the hierarchical continuous support technology of transboundary anchoring in the fault structure area was proposed. The results show that the stress near the fault area is relatively concentrated, and the rock mass strength is low, which may easily cause the deformation and failure of the surrounding rock under the dynamic stress response. Using the new technology to reconstruct the bearing structure of the broken surrounding rock mass, the deformation of the surrounding rock can be effectively restrained. According to the monitoring feedback, the roadway deformation in the roof and two sides is reduced by 68.5% and 35.4%, respectively; and the maximum evolutionary depth of the roof crack is reduced to 3.5 m from 7.5 m in the original support scheme. Moreover, this study also explored the necessity of wedge anchorage for corner anchor cables and the deformation characteristics of surrounding rock at different fault dip angles. These results provide an important reference for the maintenance and control of coal roadways under the influence of unidirectional fault structures.

Afterslip on Conjugate Faults of the 2020 Mw 6.3 Nima Earthquake in the Central Tibetan Plateau: Evidence from InSAR Measurements

ABSTRACT Afterslip could help to reveal seismogenic fault structure. The 2020 Mw 6.3 Nima earthquake happened in a pull-apart basin within the Qiangtang block, central Tibetan plateau. Previous studies have explained the coseismic and early (<6 mo) postseismic deformation by rupture and afterslip on a normal fault bounding the western side of the basin. Here, we resolved the 19-month Interferometric Synthetic Aperture Radar-measured sequences of postseismic displacements that revealed a second postseismic displacement center ~12 km to the east of the main fault. Fitting the postseismic displacement requires afterslip on both the main fault and an antithetic fault that probably forms a y-shaped pair of conjugate faults in a negative flower structure. Stress-driven afterslip models suggest that the required afterslip on the antithetic fault could be triggered by coseismic rupture of the main fault or by a simultaneous rupture on the antithetic fault. The afterslip on both faults occurred mainly up-dip to the coseismic slip and has released moment ~15%–19% of that by the coseismic rupture. These results provide insights into active extension in the central Tibetan plateau and highlight the complex nature of fault rupture and afterslip.

Simulated Rupture Dynamics and Radiated Energy on Heterogeneously Damaged Faults

AbstractRupture dynamics along a heterogeneous fault is studied in the framework of the recently developed damage‐breakage rheological model. The model utilizes a fault structure accommodating shear and wear in a heterogeneous weak fault‐core a few centimeters thick, separating two blocks with damage level gradually decreasing toward the host rock. We first demonstrate the similarity of the static stress field around a fault, represented by a three‐body tribosystem, to the one developed around a rough frictional interface. We show that both models predict heterogeneous stress field pattern. We then apply simulations of rupture on heterogeneously damaged faults. We show that increasing initial heterogeneity amplitudes is associated with smaller events with lower slip rates. The simulations further allow us to quantify the amount of accumulated damage correlative with wearing. During the propagating rupture, the strength of the fault‐core evolves, leading to higher wear generation along relatively strong zones or barriers. The total wear production in a given event is strongly dominated by the initial damage heterogeneity. Processing of synthetic seismograms shows excess energy radiation of high‐frequency seismic waves comparing to the expected radiation from planar faults. This radiation is enhanced with the increase in the variability of fault strength heterogeneity. Further calculations of the scaled energy show good fit with previous seismological and laboratory observations and demonstrate the impact of fault heterogeneity on radiated energy during dynamic rupture. Therefore, initial fault heterogeneity, manifested by fault‐core strength or by geometrical irregularity controls many aspects of earthquake rupture, including slip displacement and velocity.

Structural fault diagnosis of UAV based on convolutional neural network and data processing technology

ABSTRACT This study presents a novel method for damage detection and identification in unmanned aerial vehicles (UAVs) using vibration data gathering and processing technologies based on deep learning. To conduct the study, a quad-rotor UAV was manufactured, and a vibration data acquisition system was developed to collect vibration data along three axes under normal and three damage scenarios. Empirical mode decomposition (EMD) was employed to reduce high-frequency noise in the signals, and the root mean square error (RMSE) feature was utilised to select the Y-axis acceleration data, which exhibits significant changes across different damage cases. Finally, a convolutional neural network was used to identify the damage based on the vibration data. Experimental results demonstrate that the proposed method achieved 97.5% accuracy using selected and noise-reduced Y-axis acceleration data, thereby indicating its usefulness in diagnosing damage types in multi-rotor UAVs.

Tensile deformation behavior and strengthening mechanism of a [formula omitted] multi-principal element alloy

The microstructure and tensile deformation behavior of a Fe2.5Ni2.5CrAl multi-principal element alloy (MPEA) were investigated. The combined effect of the soft FCC phase and the hard BCC + B2 microconstituent resulted in a best-in-class strength-ductility combination. The stress–strain relationship obtained from nano-indentation tests agrees well with the tensile stress–strain curves. The fracture surface of Fe2.5Ni2.5CrAl MPEAs indicates the ductile fracture. Cracks tend to form at the interfaces of the FCC/BCC phases and expand along the voids by plastic deformation. Both dislocations and deformation twinning were responsible for the excellent properties. Second phase strengthening resulted in the largest strength increment. MD simulations revealed the formation of the HCP structure and stacking faults. Shockley dislocations were the key factor in the deformation behavior. Our study has shown best-in-class strength-ductility combination in a commercially relevant multi principal element alloy, the results are promising for several industrial applications.