Boundary Structure Research Articles

Slip Rate for the Rose Canyon Fault through San Diego, California, Based on Analysis of GPS Data: Evidence for a Potential Rose Canyon–San Miguel-Vallecitos Fault Connection?

ABSTRACT The Rose Canyon fault is the southern extension of the larger Newport–Inglewood–Rose Canyon fault system, which represents a major structural boundary in the Inner Continental Borderland (ICB) offshore of southern California. Ten to fifteen percent of total plate boundary motion in southern California is thought to be accommodated by the faults of the ICB, but the exact distribution of slip is uncertain. With an onshore segment, the Rose Canyon fault offers an opportunity to measure the slip rate using traditional geodetic methods. In this study, we use Global Positioning System (GPS) surface velocities from a combined campaign and continuous GPS network to constrain elastic models of the Rose Canyon fault. We then compare the observed surface velocities with proposed conceptual models of regional fault connections that facilitate the transfer of slip into the Rose Canyon fault to assess how well the observations are explained by the models. The results of elastic half-space models suggest that the Rose Canyon fault may be slipping toward the higher end of geologic estimates, with the preferred model indicating a slip rate of 2.4 ± 0.5 mm/yr. Although limited in terms of near-fault benchmarks, we find an improved model fit using an asymmetrical elastic half-space model and a higher slip rate, suggesting a potential rheological contrast across the Rose Canyon fault, similar to observations from the northern Newport–Inglewood fault segments. Observed GPS surface velocities, background seismicity, and gravity anomalies south of San Diego Bay point toward a more easterly trace for the Rose Canyon fault, suggesting a possible connection with the San Miguel–Vallecitos fault system. Such a connection could increase the potential rupture lengths of future earthquakes and have important consequences for regional seismic hazards.

Preparation of (Nd, Ce)-Fe-B Regenerated Magnets by In-Situ Restoration of Grain Boundary Structure Using Nascent Nd-Fe-B Powder.

Rare earth resource recycling is an important endeavor for environmental protection and resource utilization. This study explores the method of preparing regenerated magnets using waste magnets as raw materials based on existing processes. By utilizing existing Nd-Fe-B production equipment, various waste magnets are transformed into recycled powder. Next, nascent Nd-Fe-B powders with slightly higher rare earth content are selected as the repairing agent. The regenerated magnets are prepared by incorporating the nascent powder into the recycled powder. The focus lies in investigating the repairing effect of the nascent powder repairing agent on the microstructure of regenerated magnets and exploring the influence of sintering temperature and powder addition on the magnetic properties and microstructure of the regenerated magnets. The results showed that the nascent powder increased the proportion of grain boundary phases and effectively repaired the grain boundary structure of the regenerated magnets. In addition, the Pr element in the nascent powder replaces the Ce element in the recycled powder, which ultimately improves the magnetic properties of the regenerated magnet in a comprehensive manner. This study provides valuable insights and guidance for rare earth resource recycling and the preparation of regenerated magnets.

Projected pooling loss for red nucleus segmentation with soft topology constraints.

Deep learning is the standard for medical image segmentation. However, it may encounter difficulties when the training set is small. Also, it may generate anatomically aberrant segmentations. Anatomical knowledge can be potentially useful as a constraint in deep learning segmentation methods. We propose a loss function based on projected pooling to introduce soft topological constraints. Our main application is the segmentation of the red nucleus from quantitative susceptibility mapping (QSM) which is of interest in parkinsonian syndromes. This new loss function introduces soft constraints on the topology by magnifying small parts of the structure to segment to avoid that they are discarded in the segmentation process. To that purpose, we use projection of the structure onto the three planes and then use a series of MaxPooling operations with increasing kernel sizes. These operations are performed both for the ground truth and the prediction and the difference is computed to obtain the loss function. As a result, it can reduce topological errors as well as defects in the structure boundary. The approach is easy to implement and computationally efficient. When applied to the segmentation of the red nucleus from QSM data, the approach led to a very high accuracy (Dice 89.9%) and no topological errors. Moreover, the proposed loss function improved the Dice accuracy over the baseline when the training set was small. We also studied three tasks from the medical segmentation decathlon challenge (MSD) (heart, spleen, and hippocampus). For the MSD tasks, the Dice accuracies were similar for both approaches but the topological errors were reduced. We propose an effective method to automatically segment the red nucleus which is based on a new loss for introducing topology constraints in deep learning segmentation.

A comprehensive investigation of Kingery type Σ3 (111) grain boundaries in TiC, TaC, and WC

Carbide materials find extensive application as tool materials due to their exceptional properties, encompassing high hardness, wear resistance, and robust strength. Exhibiting diverse bonding characteristics, carbides constitute a pivotal material class in modern-day technologies. The structural and energetic attributes of grain boundaries play a vital role in understanding the properties of polycrystalline materials, necessitating an examination of the grain boundary regime. In this study, metal carbide grain boundaries, specifically the Kingery type Σ3 (111) grain boundaries in TiC, TaC, and WC, were systematically investigated utilizing density functional theory calculations. The scrutiny comprehends their structural, electronic, mechanical, and thermal properties. Results show that the investigated grain boundaries are energetically stable. The calculated electronic properties further unveil the presence of metallic behavior. Dynamic stability was observed at 0 K for Σ3 (111) grain boundaries constructed from the L10 cubic lattice structure in TiC, while phonon softening was observed for the Σ3 (111) grain boundaries structures in TaC and WC. Thermodynamic properties, including Helmholtz free energy, heat capacity, and entropy, were thoroughly scrutinized. Mechanical properties suggest the ductile behavior with significant metallic nature of considered grain boundary systems. The study extended to thermal properties, examining the lattice thermal conductivity (κL) of the considered grain boundary systems. It was observed that the Σ3 (111) grain boundary in TiC significantly increases the thermal conductivity.

Discrete-Ordinate-Lattice-Boltzmann Method for analyzing radiative heat transfer: Application to two-dimensional irregular enclosure

A new Discrete Ordinate-Lattice Boltzmann Method (DO-LBM) is developed by combining DOM and LBM to analyze radiative heat transfer in a two-dimensional irregular enclosure including absorbing, emitting, and scattering media. The accuracy of the proposed method was verified through Chapman-Enskog multi-scale expansion, and non-negativity analysis of the equilibrium distribution function was performed by introducing similarity numbers. Two-dimensional irregular enclosure including curved boundaries and obstacles were considered, and thn numerical results were compared with those obtained by other methods on standard problems. As a result, it was confirmed that the DO-LBM provides a valuable results in simulating radiative heat transfer in a complex boundary structure, which is simple, accurate and can reduce the computational cost compared to other methods.

Engaging to Empower: Honouring Student Sentiment and Voices to Implement a Holistic Approach in Creating an Inclusive and anti-Racist Library

Emergent issues relating to equity and inclusion have highlighted the systematic and structural inequities experienced by society, which can deeply affect our student populations. While certain events have shone a light on the overt disparities between social, ethnic, and racial groups, they have also offered academic librarians an opportunity to make changes to their ethos and practices. This article will focus on a multiyear approach implemented by a university library to become more inclusive and anti-racist in response to our students’ voices. This holistic approach will showcase creative, practical, and manageable ways that academic libraries can become more closely attuned to the needs of all our students. By making changes relating to equity, diversity, and inclusion (EDI) regarding policies, services, and collections, we can shape our practices and environment, resulting in a more transparent commitment to breaking down the structural boundaries of racism.

Fine Crust‐Mantle Structure of the Major Tectonic Boundaries Between the North China Craton and Central Asian Orogenic Belt Revealed From Rayleigh Wave Phase Velocities and Receiver Functions

AbstractThe Tanlu Fault Zone (TLFZ) and Chifeng‐Kaiyuan Fault (CKF) serve as tectonic boundaries between the North China Craton (NCC) and the Central Asian Orogenic Belt (CAOB). Clarifying the refined structure of these tectonic boundaries is crucial for understanding the relationships between the tectonic units and the heterogeneity in the destruction of the NCC. In this study, two linear seismic arrays were deployed across these tectonic boundaries. Based on the phase velocity dispersion and receiver functions extracted from the seismic arrays, the Hamiltonian Monte Carlo algorithm was employed for the joint inversion of the S‐wave velocity (Vs) in the crust and uppermost mantle. The Vs model was then used to correct the time differences in common conversion point (CCP) stacking. The CCP stacking results indicate that the boundary faults TLFZ and CKF are both whole‐crustal faults that separate the NCC and CAOB. The Vs structure showed a significant low‐velocity anomaly in the mantle beneath the NCC, with intense seismic activity within the crust. This suggests that the NCC was affected by the subduction of the Western Pacific, leading to crustal and mantle destruction. In contrast, the CAOB exhibited a clear high‐velocity anomaly with relatively stable crustal structures. We believe that the NCC and CAOB have undergone structural modification and destruction due to the closure of the Paleo‐Asian Ocean and the activities of the TLFZ since the Late Mesozoic. During the Cenozoic, the region east of the TLFZ experienced more significant destruction in the NCC than the other adjacent tectonic units.

Semi-analytical simulation of ultrasound wave propagation in large plate-like structures

The ultrasonic guided wave (UGW) has gained considerable popularity among NDE methods for damage detection and structural health monitoring (SHM) due to its high frequency and low attenuation. Lamb waves are reflected or diffracted by structure boundaries, discontinuities, and damages. It is possible to determine a structure's health, defects, and locations based on its UGW propagation characteristics. In this study, we propose an efficient modeling method for UGW propagation through damaged and scattering plates by combining the Modal Pencil method with Wave Finite Element (WFE) and Hybrid FE/WFE methods and verifying the results with a high-precision elastic finite element model (FEM). With this approach, the transducer-excited ultrasonic field can be modeled, as well as its steady-state and transient propagation, scattering, and reflections at defects and boundaries. Long-range propagation configurations can be efficiently addressed by this method because its computation efficiency is independent of propagation path lengths. As part of the case study, we study the propagation of Lamb waves through a joint metal thin-walled structure with embedded damage. In the case study, different sensor locations are used to validate the received UGW signals quantitatively. Our findings will contribute to the development of a digital twin for monitoring structural health by providing an efficient and robust approach to modeling ultrasound propagation in damaged and large plate-like structures.

Slip and stress in block-in-matrix shear zones: 1. microstructure and mineralogy of a serpentine-filled dilational jog

We document the structural setting, microstructure, and mineralogy of a crack-seal-type dilational jog that developed in the stepover between two faults cutting through a phacoid of massive serpentinite, itself embedded within a serpentinite shear zone at the base of the Dun Mountain Ophiolite, New Zealand. Our outcrop and microstructural measurements allow us to constrain the boundary conditions for a numerical model (part 2) that quantitatively explores the relationships between stress, fault slip, and incremental cracking in block-in-matrix shear zones. The dilational jog is c. 3 cm wide and contains hundreds of crack-seal bands, each c. 20–30 μm wide. Internally, the jog comprises two mineralogically distinct crack-seal domains: serpentine-only domains and serpentine-andradite garnet domains. Additionally, individual crack-seal bands have a double-layer structure: in serpentine-only domains each band comprises a thin (<2 μm) layer of chrysotile and a thicker layer (c. 25 μm) of polygonal serpentine/lizardite, whereas each band in serpentine + andradite domains comprises a thinner (c. 5 μm) layer of microcrystalline andradite and a thicker layer (c. 15 μm) of polygonal serpentine/lizardite. Micro-CT analysis shows that the serpentine + andradite domains have conic or ellipsoidal shapes with long axes subparallel to the inferred jog opening direction, and that andradite is smeared along micro-transform surfaces inside the jog. Our conceptual microstructural model invokes jog formation during progressive serpentinization of the host rock. Incremental crack opening along the jog-wall rock interface promotes relatively rapid initial precipitation of chrysotile or andradite at high fluid:rock ratios. As cracks fill and pressure re-equilibrates, relatively slow growth of polygonal serpentine/lizardite is favoured until the cracks are sealed and the cycle repeats. Our observations suggest that the precipitation of andradite (instead of chrysotile) was controlled both by structural boundaries within the jog (e.g., micro-transform surfaces) and by local element transport (e.g., Ca from serpentinizing clinopyroxene grains in the host rocks) to patches of the crack wall.

Optimizing the grain boundary structure of sintered Nd-Fe-Co-B magnets by Dy-Al-Cu alloys grain boundary diffusion

The substitution of Fe by Co can effectively increase the Curie temperature of Nd-Fe-B magnets. However, the enrichment of Co in the grain boundary phase makes the grain boundary phase change from nonmagnetic to ferromagnetic, which has a harmful effect on the coercivity. In this paper, Dy70Al10Cu20 alloy was used as the diffusion source for grain boundary diffusion of sintered Nd-Fe-Co-B magnets. The magnetic properties and microstructure of the magnets were investigated by controlling the coating thickness of the diffusion source (thickness of 0.03 mm, 0.09 mm, and 0.15 mm). The results show that the coercivity of the magnet after diffusion is increased to 17.63 kOe, which is 9.69 kOe higher than that of the undiffused magnet. The phase composition analysis shows that the original magnet contains the soft magnetic 2:17 phase, and the 2:17 phase is significantly reduced after diffusion. The microstructure observation shows that the main phase is connected and the grain boundary phase is absent in the high Co original magnet. After diffusion, the thin grain boundary phase in the magnet increases, which effectively isolates the main phase grains. Dy-rich shell is formed on the surface of the main phase grain, which is beneficial to the improvement of coercivity. Therefore, magnetic hardening of Dy-rich shells and exchange-decoupling strengthening of adjacent 2:14:1 grains isolated by intergranular phases contributed to further coercivity increment Hcj of magnet simultaneously. Studies have shown that grain boundary diffusion is an effective way to improve the microstructure of Nd-Fe-Co-B magnets.

The usage of interference effects in single Guided Ultrasonic Wave time signals for damage identification

Guided Ultrasonic Waves (GUW) interact with structural inhomogenities in multiple ways, e.g. mode conversions, mode scattering, oscillation phase shifts and reflections. These effects do occur at specimen edges and at damage on and in the specimen’s area. These effects at structural boundaries make the signal interpretation more complex. On the other hand they can lead to additional information in recorded time signals when caused by damage. This study aims at the usage of interference effects in single time signals caused by damage in the structure. This is investigated changing the location of the measurements points in relation to the damage position. Two cases are taken into account: once the damage lies in the direct measurement patch between actuator and measurement point and once the damage lies outside the measurement path and its effect on the recorded time signal is investigated. In the experimental setup, a rectangular Aluminum plate is used. Its dimension is chosen to make sure that edge reflections do not superimpose with the regarded wave packages within the time signals. A Laser-Doppler-Vibrometer allows the non-contact recording of several measurement points and is not wavelength-dependent as e.g. PZT-transducers. This allows the measurement to be unaffected by the transfer behavior of the transducers. The relationship between the specific mode wavelength reflected by the damage and the measurement path length provides information about the expected level of interference at the considered measurement point. The anticipation includes the indirect identification of damage off the direct measurement path through the observed interference effects, as well as variations in interference caused by the shift of the measurement point locations. The amplitude and phase changes serve as a measure of the interference and are obtained using the Hilbert transform.

Boundaries identification of geological structure in lunar Oceanus Procellarum region using full gravity gradient tensor methodology

Boundary recognition visually delineates the horizontal extent of subsurface anomalies, providing a foundational basis for interpreting gravity data. Compared to gravity observations, gravity gradient data offers the benefits of multiple components and the enhancement of shortwave information in graphical representations. In our study, we investigated the delineation of geological structure boundaries in the lunar Oceanus Procellarum region using gravity gradient techniques. First, based on the observations from the Gravity Recovery and Interior Laboratory (GRAIL) mission, we obtained high-precision synthetic full tensor values of the gravity gradient as our primary research data. Moreover, to reduce curvature errors during large-scale terrain forward modeling, we applied the spherical prism of tesseroid to eliminate the effects of near-surface topography. Grounded on the Bouguer anomalies of gravity gradient, four distinct boundary recognition methods have been employed to explore the geological structure of the lunar Oceanus Procellarum region. It includes the Theta map method, the directional Theta map method, the combination of total horizontal derivative and the modulus of full tensor gravity gradient, and the improved edge detection method based on the Theta map method.The common feature of these methods is the utilization of the multi-component data combination from gravity gradient tensors, which can enhance the accuracy of edge detection. From the investigation results presented in the paper, we have found the following: 1) The improved edge detection method, based on the Theta map principle, enables better identification of the center of subsurface anomaly bodies during boundary recognition, utilizing a consistent single color in graphic displays. 2) According to the results of boundary recognition, numerous strip anomalies exist in the Oceanus Procellarum area that show less correlation with topographic relief. One possible explanation for these graphical anomalies of gravity gradient is that they serve as channels for the upwelling of mantle material during lunar evolution.

SEVERE CYCLONIC STORM SITRANG: A METEOROLOGICAL ANALYSIS OF ITS FORMATION, INTENSITY, AND IMPACT ON BANGLADESH

Employing a non-central difference method of lines in tandem with the 4th order Runge-Kutta technique, this study adopts a sophisticated computational approach, ensuring precision and efficiency to resolve the shallow water equations and predict water levels caused by a cyclone in the coastal area of Bangladesh. To discretize spatial derivatives, a 4-point backward finite difference method utilized while keeping time derivatives continuous. The authors transformed the shallow water equations with boundary conditions into an initial value problem and used the Runge-Kutta(4,4) method for solving this transformed initial value problem. To effectively include the land-sea boundary and bottom structure at a reasonable charge, the authors used a high-resolution approach. To create a regular and stable tidal oscillation in the area, the authors applied the tidal component to the southern boundary of the primary model. Then ran the surge model to estimate water elevations caused by the nonlinear interaction between tide and surge. Using numerical experiments, the authors simulated water heights generated by tide, pure surge, and tide surge interaction caused by the intense cyclonic storm SITRANG. The study's simulated results demonstrate a commendable alignment with the reported data.

Sedimentology and biostratigraphy of the Biancone Limestone Formation of the Tolmin Basin (Southern Alps, NW Slovenia)

The Tolmin Basin constitutes the western part of the Slovenian Basin, a large Mesozoic interplatform basin that was bounded to the north by the Julian Carbonate Platform and to the south by the Dinaric Carbonate Platform. Today, it is found along the structural boundary between the Southern Alps and the External Dinarides in northwestern Slovenia. After the drowning of the Julian Carbonate Platform, the Tolmin Basin was dominated by pelagic deposits, namely the Toarcian marlstones (Perbla Formation), the Aalenian to lower Tithonian siliceous limestones and radiolarites (Tolmin Formation), and the upper Tithonian to the Berriasian Biancone Limestone Formation. In this study, a basin-scale sedimentary evolution and calpionellid biostratigraphy of the latter is presented. The Biancone Limestone Formation is a calpionellid-bearing pelagic limestone typical of all deepened segments of the Adria microplate in this time interval. It is generally monotonous but shows considerable vertical and lateral variations. The lower boundary with radiolarites is sharp, revealing a pronounced and rapid overturn in pelagic sedimentation. The lower Berriasian slumps indicate a tectonic pulse. Rare beds of resedimented limestones, assigned to the middle Berriasian, are similar in composition to those intercalated in the underlying radiolarites. They thus show that the factors that led to a significant shift in pelagic sedimentation had little or no effect on shallow-marine carbonate production. In the upper Berriasian, an increase in clay content is evident in the formation, which is explained by the uplift and erosion of the propagating thrust belt in the Neotethys area, superimposed by humidification.

Improved understanding of the growth of blocky alpha in welded Zircaloy-4

Zirconium alloys are widely used in nuclear reactors as fuel cladding materials. Fuel cladding is used to contain the nuclear fuel and cladding tubes are typically sealed using welds. Welding of zirconium alloys can result in changes in the local microstructure, with the potential to grow so called ‘blocky α’ grains in the welded region during subsequent thermal processing and these blocky α grains have the potential to be detrimental to the integrity of the component. In this work, complimentary heating experiments with ex situ and in situ electron backscatter diffraction (EBSD) analysis are used to aid understanding of the blocky α grain growth within the weld region. These experiments reveal that blocky α grain growth is related to the prior-β (high temperature) microstructure, as grains grow adjacent to a prior-β grain boundary and the orientation of the growing α grain can be explained using neighbourhood orientations from this prior-β grain. This growth mechanism is explained via a simple mechanism which is related to the α grain orientations, grain boundary structures and local stored energy. Ultimately, our findings indicate that the likely grain growth (size and morphology) across the weld region can now be predicted from the initial as-welded microstructure.

A facile route to synthesis NixFe1−xFe2O4 ferrofluids with optimal rheological and magneto‐optical properties

AbstractThis study presents an easy method for synthesizing ultrafine NixFe1–xFe2O4 nanoparticles with adjustable composition (x = 0–.8), followed by their stabilization into ferrofluids. Structural identification of the crystalline structure, lattice points, and grain boundaries from the broadened diffraction peaks reveal an average crystalline size of the nanoparticles as 10–16.5 nm. Transmission electron microscopy images reveal spherical magnetite nanoparticles with a particle size ranging from 6 to 13 nm, consistent with diffraction studies. In ferrofluids, the NixFe1–xFe2O4 nanoparticles are stabilized in kerosene with oleic acid, a surfactant. Absorbance data of the ferrofluids is seen in the 200–400 nm wavelength region of UV–vis spectra. The magnetic properties of the samples are probed using a Superconducting Quantum Interference Device. The synthesized samples exhibit superparamagnetic behavior at room temperature (300 K). The saturation magnetization of the samples decreases with an increase in Ni composition (x = 0–.8), ranging from 54 to 28 emu/g. This study explores the magnetic and magneto‐optical properties of NixFe1–xFe2O4 ferrofluids. Magneto‐viscosity of ferrofluids is also studied, and the final application of such ferrofluids in data storage, catalysis, and biomedical applications is discussed.

Approaches and challenges in whole-nanoparticle refinements from neutron total-scattering data

This study considers critical data reduction steps and data analysis approaches required to determine explicitly the atomic arrangements in nanoparticles from time-of-flight neutron total scattering. A practical procedure is described for removing parasitic backgrounds caused by the incoherent scattering of hydrogen inevitably present in most nanoparticle samples and normalizing the recovered coherent scattering intensities onto an absolute scale. A model-free analysis is presented of a pair-distribution function derived from total scattering that can be used to determine thermal expansion coefficients and particle sizes directly from experimental data without knowledge of the material's structure. Finally, atomistic whole-nanoparticle refinements of yttrium-doped ceria nanoparticles from neutron total-scattering data are demonstrated using the reverse Monte Carlo method implemented in the RMCProfile software. These results reveal a strong dependence of the cation–oxygen and oxygen–oxygen distances on the coordination numbers, which leads to gradients of these distances near the particle surface. The details are dependent on the surface coverage by ligands and adsorbates and on the structure of grain boundaries in nanocrystalline agglomerates. The refined models confirm the expectations of more substantial disorder at particle surfaces, with a distorted surface layer extending over several coordination shells. The results highlight the feasibility of whole-nanoparticle refinements from neutron data, calling for further development of data reduction and analysis procedures.

Effect of heat treatment on the microstructural evolution and mechanical property of nickel-based superalloy K447A manufactured by Powder Bed Fusion Laser Beam (PBF-LB)

Nickel-based superalloy is an indispensable material in the aerospace industry. With the development of metal additive manufacturing theory, the additive manufacturing technology will further expand and accelerate the application of nickel-based superalloy in the aerospace industry. In this study, nickel-base superalloy K447A with high volume fraction γ′ strengthening phase was formed by Powder Bed Fusion Laser Beam (PBF-LB), and the effect of different heat treatments on the microstructure and mechanical properties of K447A alloy was analyzed. In the as-built sample, cellular structures consisting of dense dislocation tangles were formed. Elongated columnar grains grew preferentially along <001> direction. Fine MC precipitates segregated at the boundary of cellular structure. The process of grains recovery (1185 °C), grains recrystallization (1260 °C), and grains rapid growth (1300 °C) of K447A alloy during heat treatment could be observed. Many stable and homogeneous cubic γ′ phases precipitated from the K447A alloy after high-temperature heat treatment. When the heat treatment was increased to 1300 °C, MC precipitates dissolved and the number of carbides in the ST-1300 sample was significantly reduced. The average microhardness and ultimate tensile strength of the as-built sample were 407 HV and 527 MPa, respectively. When the heat temperature reached 1260 °C, the microhardness and ultimate tensile strength reached the maximum. When the heat temperature was raised to 1300 °C, the ultimate tensile strength decreased sharply, but the elongation and the toughness increased significantly. Based on the above results, the relationship between microstructure, mechanical properties, and deformation mechanism was discussed.

A new technique based on the eigenvalue of the curvature tensor for enhancing gravity data

Enhancement of the boundaries of geologic structures is one of the main goals in interpretation of gravity anomalies. A range of different algorithms based on field derivatives has been introduced to solve this problem. Among these algorithms, the curvature gravity gradient tensor and its modifications are widely used in enhancing gravity data. These algorithms, however, have some main limitations such as the estimated edges are not compatible with the actual edges or bringing false information. In this study, I introduce a new technique based on the eigenvalue of the curvature tensor. The robustness of the presented technique is exemplified using model studies and a real-world dataset of the Vredefort dome (South Africa). The model studies show that the proposed filter can provide more accurate results and avoid artifacts in the output map. The real application result shows a good correlation between the edges highlighted by the presented algorithm and ring structures in the dome.

Experimental investigation of creep behavior along the build height of stainless-steel 316L fabricated via selective laser melting

The aim of this study was to contribute to the existing knowledge on the creep behavior of 316L stainless steel (SS) produced through selective laser melting (SLM). Creep tests were conducted on samples extracted from the wall in the build direction at 650 °C under various load conditions using a small punch (SP) creep test machine. The results revealed that the creep response was anisotropic and strongly dependent on the building height of the cubic block. Specifically, the average creep life was approximately three and five times higher in the bottom region than that in the top and middle regions, respectively. This indicates that the middle region was more susceptible to creep damage, resulting in inferior creep resistance, whereas the bottom region exhibited higher creep resistance. Interrupted tests were performed to elucidate variations in the internal creep damage level. The creep-damage mechanism was assessed based on the geometrically-necessary dislocations (GNDs) density and characteristics of the melt pool boundary (MPB). Additionally, creep tests demonstrated that SS316L stainless steel manufactured by SLM processing has an inferior creep life compared with conventional SS316L material, a phenomenon that can be attributed to the nano-sized cell structure and average grain size boundaries.