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In this study, the Discrete Element Method (DEM) was employed as a computational approach to analyse the bulk behaviour of wheat (Triticum aestivum L., cv. 'Pionier') under compressive loading. A laboratory compression apparatus was utilised as a basis for the acquisition of data from compression tests. To ensure accurate DEM predictions, the physical, mechanical, and interaction properties of wheat kernels were experimentally determined for two different moisture contents (12.4% and 25.4% w.b.). Five particle models were constructed to represent the geometric shape of the kernel, with the model composed of five sub-spheres identified as the most suitable, ensuring an optimal balance between computational complexity and simulation accuracy. The bulk compression results from DEM simulations were compared to experimental data, revealing a good agreement for volumetric strain, bulk density increase, and bulk compressibility within the specified range of applicability. Simulations provided valuable insights into temporal and spatial variations of forces and deformations acting on individual particles, thereby enhancing the understanding of bulk behaviour at different compression levels. The moisture content was found to significantly affect the particle compressive forces, deformation capabilities, and bulk compression characteristics. In conclusion, this study demonstrated the great potential of DEM in predicting the bulk behaviour of wheat under compression, providing valuable information for practical storage and handling processes. • Bulk behaviour of wheat during compressive loading was studied using DEM. • DEM-relevant modelling parameters were determined experimentally. • Bulk volumetric strain, bulk density and compressibility were investigated. • Mechanical response of particles under bulk compression was analysed. • Moisture content effect on product properties and compression characteristics was examined. [ABSTRACT FROM AUTHOR]

With the launch of very high resolution (VHR) satellites such as the Cartosat-2S series, Cartosat-3, WorldView-series, Pleiades-Neo series in the recent past, high resolution digital surface models (DEMs) with ~1 m grid interval can be generated using high resolution stereo images using the approach of digital photogrammetry. These high resolution DEMs are very handy for applications in city modelling, change detection, disaster management, infrastructure planning and so on. In this study, high resolution DEM is generated at a grid interval of 1 m using Cartosat-2S across-track images (0.65 m resolution) and WorldView-3 in-track stereo images (0.31 m resolution) over a small region over Mumbai. Both the generated DEMs are compared with each other in qualitative and quantitative ways and their relative accuracies are evaluated towards accurate city modelling. [ABSTRACT FROM AUTHOR]

AbstractVibratory conveying equipment is widely used in industry and agriculture. The choice of operating parameters has a significant influence on the conveying velocity. Herein, the velocity of a particle under equal vibration intensity conditions is investigated using a frequency-adjustable vibratory feeder. The discrete element method was used to study the motion regularities of a particle on a vibrating conveyor. The effects of the amplitude, vibration direction angle, inclination angle, and vibration intensity on the transport velocity of the vibrating conveyor were investigated using the response surface method. The experimental and calculate results demonstrate that the simulation method and the model is reliable. When the vibration intensity is greater than Kc and remains constant, increasing the amplitude increases the velocity of particle motion. A large vibration direction angle enhances the throwing motion of the particle. A large inclination angle enhances the sliding motion. The inclination angle is used to increase transport velocity by enhancing forward sliding and attenuating backward sliding. The response surface analysis shows that the particle motion velocity is more evidently influenced by the amplitude, followed by the installation inclination and vibration direction angles. The results of the study are important for optimizing the design and operating parameters of vibratory conveying equipment. [ABSTRACT FROM AUTHOR]

High-pressure grinding rolls (HPGR) have increased their popularity in the minerals industry, since their first application in the 1980s for raw material preparation in the cement industry. Recent advances on the technology have been responsible for putting it in a prominent position among comminution processes, with applications that now range from tertiary crushing stages to pressing iron ore concentrates prior to pelletization. This work reviews some of the recent advances in the technology applied to the minerals industry, including efforts toward improvement on roll lifetime, understanding the effect of progressive roll surface wear on machine performance, alternative lateral confinement systems, the phenomenon of skewing and entirely novel machine designs. Such advances, besides recent insights into the equipment operation, are analyzed, whenever possible, with the assistance of advanced simulation tools, in particular, the discrete element method (DEM). [ABSTRACT FROM AUTHOR]

The unique P-band synthetic aperture radar (SAR) instrument, BIOMASS, is scheduled for launch in 2024. This satellite will enhance the estimation of subcanopy topography, owing to its strong penetration and fully polarimetric observation capability. In order to conduct global-scale mapping of the subcanopy topography, it is crucial to calibrate systematic errors of different strips through interferometric SAR (InSAR) DEM (digital elevation model) block adjustment. Furthermore, the BIOMASS mission will operate in repeat-pass interferometric mode, facing the atmospheric delay errors introduced by changes in atmospheric conditions. However, the existing block adjustment methods aim to calibrate systematic errors in bistatic mode, which can avoid possible errors from atmospheric effects through interferometry. Therefore, there is still a lack of systematic error calibration methods under the interference of atmospheric effects. To address this issue, we propose a block adjustment model considering atmospheric effects. Our model begins by employing the sub-aperture decomposition technique to form forward-looking and backward-looking interferograms, then multi-resolution weighted correlation analysis based on sub-aperture interferograms (SA-MRWCA) is utilized to detect atmospheric delay errors. Subsequently, the block adjustment model considering atmospheric effects can be established based on the SA-MRWCA. Finally, we use robust Helmert variance component estimation (RHVCE) to build the posterior stochastic model to improve parameter estimation accuracy. Due to the lack of spaceborne P-band data, this paper utilized L-band Advanced Land Observing Satellite (ALOS)-1 PALSAR data, which is also long-wavelength, to emulate systematic error calibration of the BIOMASS mission. We chose climatically diverse inland regions of Asia and the coastal regions of South America to assess the model's effectiveness. The results show that the proposed block adjustment model considering atmospheric effects improved accuracy by 72.2% in the inland test site, with root mean square error (RMSE) decreasing from 10.85 m to 3.02 m. Moreover, the accuracy in the coastal test site improved by 80.2%, with RMSE decreasing from 16.19 m to 3.22 m. [ABSTRACT FROM AUTHOR]

The discrete element method (DEM) is used widely to study the crushing behaviour of granular materials from a microscale perspective. However, a crushing criterion that can be suitable for triggering particle crushing for different coordination numbers (CNs) is still lacking. To develop a crushing criterion, particle crushing tests are conducted for different CNs via the DEM. Crushable spherical agglomerates are made by bonding smaller sub-spheres. Based on the results of simulations, a new crushing criterion invariant to the coordination number effect is proposed. The crushing criterion is simply expressed in terms of the three principal stresses of the particles. Furthermore, the applicability of the criterion is verified under various conditions, such as different numbers of sub-sphere, shapes of particles, microscale parameters and loading patterns. By using the new criterion, the particle strengths obtained from the single particle crushing tests can be used as the crushing strengths for the particles under multiple contact loading conditions in DEM simulations. [ABSTRACT FROM AUTHOR]

Although the cardioid-shaped traffic loading path can be implemented using hollow cylinder apparatus, the preparation of inherently anisotropic sand with different bedding plane angles could be difficult. Consequently, the macro-scale response of inherently anisotropic sand under traffic loading has not been adequately investigated to reveal the underlying microscopic mechanism. In this paper, elongated particles with various aspect ratios were used to approximate the natural sand particles, and uniform three-dimensional specimens with different bedding plane angles were generated using discrete element method based on a modified version of under-compaction method. The cardioid-shaped loading path was implemented using an advanced servomechanism that can apply arbitrary loading paths. The internal structure of specimen was quantified through a contact-normal-based fabric tensor, which could describe the load-bearing structure of granular specimens. The interplay between the macro-scale observations and the fabric evolutions was elucidated. The influences of both bedding plane angle and aspect ratio on the accumulations of volumetric strain and generalized shear strain are not monotonic, with the largest strains at the bedding plane angle of 45° and the aspect ratio of 1.4. Results provide useful insights into the underlying mechanism of the deformation behavior of inherently anisotropic granular materials under traffic loading. [ABSTRACT FROM AUTHOR]

In this study, three randomly packed beds with varying tube-to-particle diameter ratios (D/d) are constructed using the discrete element method (DEM) and simulated via CFD under low pore Reynolds numbers (Rep < 100). An innovation of this research lies in the application of hydrogen in randomly packed beds, coupled with the consideration of its temperature-dependent thermal properties. The axial analysis of the heat transfer characteristics shows that PB−5 and PB−6 achieve thermal equilibrium 44% and 58% faster than PB−4, respectively, demonstrating enhanced heat transfer efficiency. However, at higher flow rates (0.8 m/s), the large-sized fluid channels in PB−6 severely impact the heat transfer efficiency, slightly reducing it compared to PB−5. Additionally, this study introduces a localized segmentation method for calculating the axial local Nusselt number, showing that the axial local Nusselt number (Nu) not only exhibits an inverse relationship with the axial porosity distribution, but also matches its amplitude fluctuations. The wall effect significantly impacts the flow and temperature distribution in the packed bed, causing notable velocity and temperature oscillations in the near-wall region. In the near-wall region, the average temperature is lower than in the core region, and the axial temperature profile exhibits more intense oscillations. These findings may provide insights into the use of hydrogen in randomly packed beds, which are vital for enhancing industrial applications such as hydrogen storage and utilization. [ABSTRACT FROM AUTHOR]

This study investigates the dynamics of granular flows in geotechnical centrifuge models, focusing on the effects of centrifugal and Coriolis accelerations. While conventional laboratory-scale investigations often rely on Froude scaling, geotechnical centrifuge modelling offers a unique advantage in incorporating stress-dependent processes that fundamentally shape flow rheology and dynamics. Using the Discrete Element Method (DEM) and the Lattice-Boltzmann Method (LBM), we simulate the collapse of a just-saturated granular column within a rotating reference frame. The model’s accuracy is validated against expected trends and physical experiments, demonstrating its strong performance in replicating idealised collapse behaviour. Acceleration effects on both macro- and grain-scale dynamics are examined through phase front and coordination number analysis, providing insight on how centrifugal and Coriolis accelerations influence flow structure and mobility. This work enhances our understanding of granular flow dynamics in geotechnical centrifuge models by introducing an interstitial pore fluid and considering multiple factors that influence flow behaviour over a wide parameter space. [ABSTRACT FROM AUTHOR]

Rockfall frequently occurs in the mountainous areas and threatens structures such as settlement areas, transportation lines, and agricultural field. The empirical approaches for rockfall mapping have been an attractive research topic in rock mechanics in the recent years, because producing rockfall maps of large areas by using the deterministic and the probabilistic analysis seems difficult due to the necessity of numerous inputs. The cone propagation approach is preferred as a practical tool particularly in the regional scale. The digital elevation model (DEM) of a region prone to rockfall is used for determination of possible propagation zones based on a simple geometric rule known as the energy line angle (reach angle). As a new term, ELAmax_stop was defined to represent the energy line angle that extends to the border of the propagation zone as the maximum run-out distance that is obtained from application of the cone approach to all points (pixels) in source area. The angle denoted as α refers to the threshold slope angle of the steep areas utilized to identify potential source areas by using DEM. Conceptually, the fallen rock blocks within a rockfall-prone region stop within the cone propagation zone, which is bounded by the energy line angles α and ELAmax_stop. While the value of α is susceptible to the resolution of DEM, ELAmax_stop, which exhibits a wide angle range as documented in the literature, is controlled by rock block features together with slope surface properties of the propagation zone. Due to the variability of ELAmax_stop and α depending on the studied region and the resolution of the DEM, the boundary value of the energy line angles between different susceptibility classes need to be adjusted by considering α and ELAmax_stop. By adopting the cone propagation approach to enable adjustable use of energy line angles for rockfall susceptibility mapping, a series of graphical presentations was prepared. These graphical presentations allowed for the prediction of energy line angles corresponding to various rockfall susceptibility classes including very low, low, medium, high, and very high. In addition to the graphical presentations, a series of practical equations were derived for the same purpose. In the final part of the study, a new rating system, namely the run-out distance rating (RDR), was introduced for the preliminary determination of ELAmax_stop. Due to the empirical structure of the methodology, the suggested supportive approach to the practitioners for determining ELAmax_stop should be considered as an initial step that opens to improvement. The proposed methodology in this study was implemented in the regions of Kargabedir Hill and Sivrihisar residential areas in Turkey to prepare rockfall susceptibility maps. [ABSTRACT FROM AUTHOR]

Pile foundations frequently endure dynamic loads, necessitating an in‐depth examination of the cyclic shear properties at the pile–soil interface. This study involved a series of cyclic direct shear (CDS) tests conducted on sand and concrete with irregular surface, utilizing varying displacement amplitudes (1, 3, 6, and 10 mm) and joint roughness coefficients (0.4, 5.8, 9.5, 12.8, and 16.7). Discrete Element Method (DEM) models, informed by experimental data, facilitated mesoscopic mechanical response analyses. Findings indicate that the sand–concrete interface undergoes softening, with hysteresis loops' morphology dependent largely on displacement amplitude. A maximum ultimate shear stress corresponds to a specific critical surface roughness, while the initial tangent modulus escalates with increased concrete roughness. Volume variations of the specimen inversely correlate with displacement amplitude and directly with surface roughness. As displacement amplitude expands, there is a reduction in the maximum shear stiffness and an elevation in the maximum damping ratio. Empirical formulas for the surface roughness and normalized shear stiffness were proposed. Larger displacement amplitudes result in more substantial shear bands and heightened energy dissipation, yet the incremental energy ratio remains largely unaffected. Predominant energy dissipation mechanisms include both slip and rolling slip, with the former surpassing the latter in energy dissipation capacity. The anisotropy directions of contact normal, normal contact forces, and tangential contact forces consistently fluctuate with shear direction alterations. [ABSTRACT FROM AUTHOR]

This paper demonstrates the latest developments in particle-scale modelling of a clay. It shows that by creating an initial sample of platelets featuring aggregated stacks, excellent macroscopic behaviour is achieved. This approach is justified by examining SEM images of clay slurries, and is consistent with the behaviour of real clays. The use of aggregated stacks allows a wider range of platelet interactions and micro properties to be simulated and investigated, and significantly, enables interactions to be modelled that are based on a range of real measurements obtained from surface force experiments. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicle light detection and ranging (UAV‐lidar) and unmanned aerial vehicle (UAV) photogrammetry are currently commonly used surface monitoring technologies. Previous studies have used the two technologies interchangeably and ignored their correlation, or only compared them on a single product. However, there are few quantitative assessments of the differences between these two techniques in monitoring surface deformation and prediction of their application prospects. Therefore, the paper compared the differences between the digital elevation model (DEM) and subsidence basins obtained by the two techniques using Gaussian analysis. The results indicate that the surface DEMs obtained by both the techniques exhibit a high degree of similarity. The statistical analysis of the difference values in the z direction between the two DEMs follows a Gaussian distribution with a standard deviation of less than 0.36 m. When comparing the surface subsidence values monitored by the two techniques, it was found that UAV‐lidar was more sensitive to small‐scale deformation, with a difference range of 0.23–0.44 m compared to photogrammetry. The conclusion provides valuable information regarding the utilisation of multisource monitoring data. [ABSTRACT FROM AUTHOR]

A numerical investigation of the influence of porosity, pore size, and planar defects (microcracks) on the elastic constants, compressive and tensile strength of a fine-grained matrix in a SiO2 refractory ceramics is presented. The modeling results show a qualitatively different effect of the 3D (pores) and 2D (microcracks) defects on its effective elastic properties. An increase in porosity leads to a decrease in Young's modulus and the strength of the refractory matrix, while the trend in the Poisson's ratio behavior depends on the degree of pore structure connectivity. Microcracks also reduce the effective strength and Young's modulus of the matrix but, unlike the pores, they cause an asymmetry in the effective elastic properties. The Young's modulus of the matrix decreases more slowly under compression than under tension, and the Poisson's ratio trend is the opposite (an increase under compression and a decrease under tension). The quantitative estimates of the effective mechanical characteristics of the fine grain matrix can be used in multiscale computer models of traditional and advanced SiO2-based refractories. [ABSTRACT FROM AUTHOR]

The stress‐induced dilatancy anisotropy is an important kinematic response in granular materials and is very complex due to the stochastic motion of particles. In this study, the local stress‐dilatancy relationship is investigated referring to the local contact force and relative displacement in a certain contact direction. The micromechanism of this anisotropy is investigated from the view of affine and nonaffine approaches based on DEM simulation. Numerical results indicate that the local nonaffine dilatancy/contraction tendency is opposite with that of local affine deformation in macroscopic compression and extension direction, which mainly stems from the counteraction effect between the normal components of affine and nonaffine displacements. The local stress‐dilatancy of affine and nonaffine components is linear and orientation‐dependent, which results in the nonlinear character of macroscopic stress‐dilatancy. By establishing an analytical relation of stress‐dilatancy, the local affine/nonaffine dilatancy is decomposed into the component of stress‐induced dilatancy synchronized with the local stress anisotropy; and the component of stress‐induced dilatancy asynchronized with the local stress anisotropy. The former is related to the unchanged isotropic microstructure, and the latter attributes to the anisotropic microstructure. Besides, the contribution of nonsliding contacts to nonaffine dilatancy is larger than that of sliding contacts even for the case of relatively higher sliding ratio, which indicates that the heterogeneous deformation attributes not only to the friction dissipation, but to the blocked energy at micro contacts in granular materials. [ABSTRACT FROM AUTHOR]

The bearing resistance provided by the geogrid's transverse ribs is a non-negligible aspect of the strength mechanism in mobilizing the geogrid–soil interface. Therefore, studying its influence on the response mechanism of geosynthetic-reinforced soil structures under cyclic loading is crucial. The stereoscopic geogrids were manufactured using 3D printing technology by quantitatively thickening the transverse ribs of planar geogrids. To investigate the cyclic hysteresis relationship and stress–dilatancy phase-transformation characteristics of the stereoscopic geogrid–coarse particle interface, cyclic direct shear tests were conducted. Additionally, a discrete element method (DEM) was employed to study the evolution of shear bands and fabric anisotropy at the interface under cyclic loading. The results of the study indicate that the stress–displacement phase angle of the stereoscopic geogrid in the horizontal direction of cyclic shear is smaller compared to the planar geogrid. Furthermore, thickening the transverse ribs decreases the stress–dilatancy phase-transformation angle of the interface. The thickness of the interface shear band in the stereoscopic geogrid is greater than that of the planar geogrid. Moreover, as the transverse-rib thickness increases, the principal direction of the average normal contact force and average tangential contact force under cyclic loading also increases. • Highlights the macroscopic and mesoscopic behavior of the 3D printed stereoscopic geogrid–coarse grain interface under cyclic shearing. • Comparing the interface stress–dilatancy phase-transformation angle of planar geogrids and stereoscopic geogrids. • The effect of transverse-rib thickness on the evolution of shear band and fabric anisotropy was quantified. [ABSTRACT FROM AUTHOR]

Lake volume variation is closely related to climate change and human activities, which can be monitored by multi-source remote-sensing data from space. Although there are usually two routine ways to construct the lake volume by the digital elevation model (DEM) or satellite altimetric data combined with the lake area, rarely has a comparison been made between the two methods. Therefore, we conducted a comparison between the two methods in Texas for 14 lakes with abundant validation data. First, we constructed the lake hypsometric curve by five commonly applied DEMs (SRTM, ASTER, ALOS, GMTED2010, and NED) or satellite altimetric products combined with the gauge lake area. Second, the lake volume was estimated by combining the hypsometric curve with the gauge lake area time series. Finally, the estimation error has been quantitatively calculated. The results show that the relative lake volume estimation error (rVSD) of the altimetric data (4%) is only 10–18% of that of the DEMs (22–41%), and the DEM with the highest resolution (NED) has the least rVSD with an average of 22%. Therefore, for large-scale lake monitoring, we suggest the application of satellite altimetric data with the lake area to estimate the lake volume of large lakes, and the application of high-resolution DEM with the lake area to calculate the lake volume of small lakes that are gapped by satellite altimetric data. [ABSTRACT FROM AUTHOR]

Slope length is an important factor in soil erosion modeling, and the reasonable automatic extraction of slope length is of great significance in soil erosion research. However, previous studies have mainly focused on the regional scale, and how to effectively extract slope length at the slope scale deserves further research. In this study, a slope length extraction algorithm based on slope streamlines method (SSM) is proposed for the slope length extraction problem in geomorphology, and it is compared with three existing slope length calculation methods. The experimental results show that the new method can quickly calculate the length of slope streamlines, and the extracted slope lengths have better accuracy; the coefficients of determination demonstrates a better overall fitting effect of the four extraction methods, with coefficients of determination exceeding 0.7; this indicates that the use of SSM has similar accuracy and stability to other methods in calculating slope lengths. Among all the calculation methods, SSM has a better overall fitting effect for slope length calculation, and the obtained slope length value domain range is relatively small and concentrated in a small range, which expresses the slope length better. [ABSTRACT FROM AUTHOR]

In Discrete Element Method (DEM), the stiffness of particles is often reduced artificially for calculation speed-up. It is known that the attraction force and rolling resistance should be scaled to counter-balance the excessive energy dissipation caused by prolonged contact duration with reduced stiffness. The present study theoretically derives the scaling laws from dimensionless equations of motion in a generic form, which are for both particle translation and rotation and with multi-body interactions. It is verified that the proposed scaling laws keep the same particle motion in the dimensionless time and space during the contact of more than two particles. It is also demonstrated that the behaviour of the original (stiff) particles in Couette flow can be replicated well in various conditions in general. Some deviation to the original system could be observed in certain conditions, which is likely related to the reduction of contact frequency. • Artificially reduced stiffness is used in DEM for simulation speed-up. • Generic scaling laws of attraction forces and rolling resistances are theoretically derived. • Multi-body interactions are considered in the derivation. • The scaling laws maintain the same particle behaviour in dimensionless time and space. • The effectiveness and limitations of the scaling laws are discussed. [ABSTRACT FROM AUTHOR]

The Caleva UK single-screw Variable Density Extruder (VDE) is a continuous powder processing equipment known for spheronization and extrusion. Its suitability for granulation remains uncertain, a common challenge in powder processing industries that deal with granules, pellets, and tablets. This study investigates the VDE's potential for granulation, using 65 µm CaCO3 powder and PEG 4000 as a liquid binder. In order to replicate several experimental setups with varying binder concentrations and liquid-to-solid ratios (L/S) of 0.1 and 0.15, eight DEM simulations were run. Our results indicate that higher binder concentrations yield more consistent products with fewer fines, while lower concentrations result in inconsistent products with increased fines. Low L/S ratios produce fragile, fine-sized products with a broad particle size distribution (PSD). DEM simulations reveal a direct relationship between liquid binder content and contact forces. Analysis of bonds formed, and particle counts in simulations corroborates experimental observations of fines production. Additionally, granule strength appears to be directly proportional to contact force. [Display omitted] • L/S is the most influencing parameter with regards to granule strength and GSD. • Lower binder concentration produced nonhomogeneous products with more fines. • Lower L/S ratio result in more fragile granules and a wide range of GSD. • Mean strength of granules is directly proportional to contact force in simulations. • DEM Results validated through comparison with experimental data. [ABSTRACT FROM AUTHOR]

The lunar orbiter laser altimeter (LOLA) onboard the lunar reconnaissance orbiter has performed high-precision, full-coverage, and high-density laser ranging observations for the entire lunar surface since its launch. Statistics have shown that LOLA has collected 6.94 billion effective altimeter data up to June 2022. Most of the typical orbits in the LOLA dataset have a high quality and exhibit horizontal offsets of almost 7 m and radial offsets of almost 0.5 m. However, there is still a category of orbits in the dataset that will cause apparent noise in the constructed DEM, which is attributed to the orbits with large or anomalous errors. We call such orbits as flawed orbits in this paper. The flawed orbits can be identified and screened by the elevation discrepancy at the crossovers of the orbits. The results show that the flawed orbits are caused by significant along-track errors, which also result in the radial error of up to several kilometers. Moreover, most of the flawed orbits are concentrated in several consecutive time intervals. A correction method is then proposed to correct the flawed orbits in the local region. The position of the flawed orbits is reconstructed using the feature points matching of the DEMs before and after they are removed. Some experimental analyzes show that the apparent terrain artifacts have been eliminated and more identifiable terrain details are reappeared. Identifying and correcting these flawed orbits with significant along-track offsets paves the way for improving the quality of the LOLA data and reconstructing the topography of the Moon. [ABSTRACT FROM AUTHOR]

To address the landslide recognition problem in remote sensing images, this paper designs a visual transformer network model based on DEM (digital elevation model) feature enhancement, which is experimentally validated on the Bijie landslide dataset and Landslide4Sense2022 dataset. The lion optimizer is used during training. The results show that 98.49% accuracy and 97.24% F1 score are achieved on Bijie dataset, and 88.22% accuracy and 90.16% F1 score on Landslide4Sense2022 dataset, which is a significant improvement in landslide recognition compared with other mainstream network models. Therefore, it can be found that this paper's method is effective in the recognition of landslide from remote sensing images. Firstly, the swin transformer network model was successfully applied to remote sensing landslide image classification by means of transfer learning. Secondly, an information enhancement approach based on DEM features was designed. [ABSTRACT FROM AUTHOR]

Mapping and quantification of forest biomass change are key for forest management and for forests' contribution to the global carbon budget. We explored the potential of covering this with repeated acquisitions with TanDEM-X. We used an eight-year period in a Tanzanian miombo woodland as a test case, having repeated TanDEM-X elevation data for this period and repeated field inventory data. We also investigated the use of GEDI space–LiDAR footprint AGB estimates as an alternative to field inventory. The map of TanDEM-X elevation change appeared to be an accurate representation of the geography of forest biomass change. The relationship between TanDEM-X phase height and above-ground biomass (AGB) could be represented as a straight line passing through the origin, and this relationship was the same at both the beginning and end of the period. We obtained a similar relationship when we replaced field plot data with the GEDI data. In conclusion, temporal change in miombo woodland biomass is closely related to change in InSAR elevation, and this enabled both an accurate mapping and quantification wall to wall within 5–10% error margins. The combination of TanDEM-X and GEDI may have a near-global potential for estimation of temporal change in forest biomass. [ABSTRACT FROM AUTHOR]

The digital elevation model (DEM) and its derived morphometric factors, i.e., slope, aspect, profile and plan curvatures, and topographic wetness index (TWI), are essential for natural hazard modeling and prediction as they provide critical information about the terrain's characteristics that can influence the likelihood and severity of natural hazards. Therefore, increasing the accuracy of the DEM and its derived factors plays a critical role. The primary aim of this study is to evaluate and compare the effects of resampling and downscaling the DEM from low to medium resolution and from medium to high resolutions using four methods: namely the Hopfield Neural Network (HNN), Bilinear, Bicubic, and Kriging, on five morphometric factors derived from it. A geospatial database was established, comprising five DEMs with different resolutions: specifically, a SRTM DEM with 30 m resolution, a 20 m resolution DEM derived from topographic maps at a scale of 50,000, a 10 m resolution DEM generated from topographic maps at a scale of 10,000, a 5 m resolution DEM created using surveying points with total stations, and a 5 m resolution DEM constructed through drone photogrammetry. The accuracy of the resampling and downscaling was assessed using Root Mean Square Error (RMSE) and mean absolute error (MAE) as statistical metrics. The results indicate that, in the case of downscaling from low to medium resolution, all four methods—HNN, Bilinear, Bicubic, and Kriging—significantly improve the accuracy of slope, aspect, profile and plan curvatures, and TWI. However, for the case of medium to high resolutions, further investigations are needed as the improvement in accuracy observed in the DEMs does not necessarily translate to the improvement of the second derivative morphometric factors such as plan and profile curvatures and TWI. While RMSEs of the first derivatives of DEMs, such as slope and aspect, reduced in a range of 8% to 55% in all five datasets, the RMSEs of curvatures and TWI slightly increased in cases of downscaling and resampling of Dataset 4. Among the four methods, the HNN method provides the highest accuracy, followed by the bicubic method. The statistics showed that in all five cases of the experiment, the HNN downscaling reduced the RMSE and MAE by 55% for the best case and 10% for the worst case for slope, and it reduced the RMSE by 50% for the best case of aspect. Both the HNN and the bicubic methods outperform the Kriging and bilinear methods. Therefore, we highly recommend using the HNN method for downscaling DEMs to produce more accurate morphometric factors, slope, aspect, profile and plan curvatures, and TWI. [ABSTRACT FROM AUTHOR]

The topography of bedrock beneath an ice sheet is one of the several factors that influence the flow of ice. It has the potential to change the direction of ice movement, which can lead to confusion when interpreting glacial striae and landforms. In the Mistassini area in Canada, formerly glaciated by the Laurentide Ice Sheet during several phases of the Quaternary, we used a high-resolution digital elevation model to calculate hillshade, slope gradient, and slope aspect. These derived topographic parameters were then combined with mapped glacial indicators to investigate how the underlying bedrock topography potentially influenced the direction of ice flow. The results show that during the older southeastward (SE) event, there was a notable deflection of the ice towards the south in the southern part of the study area. During the southward (S) event, and to a lesser extent south–southeastward (SSE) event, the impact of bedrock topography on ice movement appears to be less pronounced than during the previous southeastward phase (SE). As the ice gradually thinned during the final south–southwestward flow (SSW), the ice sheet became increasingly sensitive to the local bedrock topography. This sensitivity was particularly pronounced in the southern part of the area, where a dominant north-south topographic pattern constrained the ice to flow towards the south. This study demonstrates the feasibility of conducting a quick assessment of the influence of bedrock topography on paleo-ice flows through morphometric analysis of current topography and glacial evidence preserved on bedrock surfaces. [ABSTRACT FROM AUTHOR]

The shape of the failure locus of a material is significant for its strength predictions. Even when constitutive models include the same critical stress surface, different critical stress ratios can be predicted for an identical applied isochoric strain path. In this article, we investigate critical stress predictions of different constitutive models, which include the surface according to Matsuoka–Nakai (MN). We perform analytical investigations, true triaxial test simulations with hypoplasticity and barodesy, and discrete element modelling (DEM) simulations to investigate the friction dependency of the stress Lode angle. Our results demonstrate that in hypoplasticity, the direction of the deviatoric stress state at critical state depends solely on the direction of the applied deviatoric strain path. In contrast, in barodesy, the predictions are also dependent on the friction angle of the material. In addition, we compare these results with those obtained with a standard elastoplastic MN model. To validate this friction dependency on the stress Lode angle, we conduct DEM simulations. The DEM results qualitatively support the predictions of barodesy and suggest that a higher friction results in a higher Lode angle at critical stress state. [ABSTRACT FROM AUTHOR]

When the first Americans inhabited the area now known as Isla Espiritu Santo, around 12.5 and 6 ka, the sea level continuously rose. This resulted in the loss of the coastal territory and the retreat of the human population further inland. Part of the archaeological evidence of this period currently lies over the seafloor and under the seabed. Therefore, reconstructing paleoshorelines is a necessary first step toward submerged precontact archaeology and a broad understanding of the spatial context in which those human populations interacted and how the landscapes changed. Isla Espiritu Santo is of prehistoric importance as it contains numerous Paleocoastal tradition sites as early as ~12,400 Cal B.P. This research aims to reconstruct the changing shoreline positions as sea levels rose around Isla Espiritu Santo between 12.5 and 6.5 ka. We apply numerical modeling to map digital elevation models at 1 ka intervals by estimating the changes in the morphology of the seafloor according to the deposition rates and global sea‐level curve. The results show the evolution of coastal morphology and paleoshoreline's position. Three primary geoforms are proposed: (1) coastal plains, (2) tombolo, and (3) a coastal lagoon–island barrier system. This also offers insights into the physical aspect of submerged prehistoric landscapes and the possible resource exploitation options of early societies. In this research, the reconstruction of submerged landscapes seeks to contribute to the long‐term goal of locating submerged precontact sites. [ABSTRACT FROM AUTHOR]

Fabric influences the macro scale mechanical properties and behavior of granular materials as a continuum and can be represented by an appropriately defined evolving fabric tensor entering the constitutive equations. In this study, the evolution of fabric tensors under cyclic loading is investigated and quantified by a series of cyclic loading DEM tests. Simulations of the DEM data are made by two different continuum evolution rate equations for the contact normal‐based fabric tensor, both within the Anisotropic Critical State Theory (ACST) framework: the first, is a Basic Fabric Evolution (BFE) equation and the second, is a novel Combined Fabric Evolution (CFE) equation, where a quantity related to particle‐based fabric tensor is considered. The comparison with DEM results highlights the capability of the CFE equation in simulating fabric evolution under cyclic loading for different anisotropy, density, and loading conditions. In addition, such simulations are significantly more accurate in comparison with those obtained by the BFE equation. The reason for the superiority of CFE over the BFE is the incorporation of the influence of the particle orientation fabric on contact normal fabric evolution. Analytical evaluation of CFE further identifies a total of seven periodic stable contact normal fabric evolution patterns that exist under cyclic loading, governed by initial void ratio, intensity of anisotropy, and stress amplitude. The limitation of current fabric evolution equations in being able to only reflect the proportional coaxial part of the fabric tensor with respect to the loading direction is discussed. [ABSTRACT FROM AUTHOR]

The rapidly developing mining industry poses the urgent problem of increasing the energy efficiency of the operation of basic equipment, such as semi-autogenous grinding (SAG) mills. For this purpose, a large number of studies have been carried out on the establishment of optimal operating parameters of the mill, the development of the design of lifters, the rational selection of their materials, etc. However, the dependence of operating parameters on the properties of the ore, the design of the linings and the wear of lifters has not been sufficiently studied. This work analyzes the process of grinding rock in SAG mill and the wear of lifters. The discrete element method (DEM) was used to simulate the grinding of apatite-nepheline ore in a mill using different types of linings and determining the process parameters. It was found that the liners operating in cascade mode were subjected to impact-abrasive wear, while the liners with the cascade mode of operation were subjected predominantly to abrasive wear. At the same time, the results showed an average 40–50% reduction in linear wear. On the basis of modelling results, the service life of lifters was calculated. It is concluded that the Archard model makes it possible to reproduce with sufficient accuracy the wear processes occurring in the mills, taking into account the physical and mechanical properties of the specified materials. The control system design for the grinding process for SAG mills with the use of modern variable frequency drives (VFD) was developed. With the use of the proposed approach, the model predictive control (MPC) was developed to provide recommendations for controlling the optimum speed of the mill drum rotation. [ABSTRACT FROM AUTHOR]

In this study, we investigated the applicability of five open-access, satellite-derived DEMs with resolutions of ∼90 m (MERIT-Hydro and TanDEM-X), ∼30 m (SRTM and ALOS), and ∼8.1 m (DEMNAS) to rain-on-grid modeling (with HEC-RAS) for flood hydrograph prediction in the Katulampa watershed, Indonesia. Additionally, the influence of the Manning coefficient and infiltration values on the modeling results was also investigated based on three types of land use (forest, agriculture, and urban area). It was shown that ALOS (∼30 m) was the most accurate data among other DEMs to predict flood hydrographs. Interestingly, MERIT-Hydro (∼90 m) significantly outperformed SRTM (∼30 m) and DEMNAS (∼8.1 m), indicating that DEMs with finer-resolution are not necessarily more accurate than coarser-resolution DEMs for rain-on-grid modeling. Furthermore, we observed that the modeling results were strongly influenced by the Manning coefficient and infiltration values, indicating the importance of calibration for such values. Based on 279 combinations carried out, only agriculture was sensitive to both Manning coefficient and infiltration values, while forest and urban were not. The Manning coefficients calibrated for each land use data were similar for different flood events. However, only the infiltration values calibrated for agriculture were distinct for different flood events, thus emphasizing the need for individual calibrations of infiltration values for each event. Our findings are useful to demonstrate how rain-on-grid modeling – with proper DEM data and the calibrated Manning coefficient and infiltration values – can be utilized for accurate flood hydrograph predictions. [ABSTRACT FROM AUTHOR]

Remote sensing (RS) techniques are essential for studying hazardous landslide events because they capture information and monitor sites at scale. They enable analyzing causes and impacts of ongoing events for disaster management. There has been a plethora of work in the literature mostly discussing (1) applications to detect, monitor, and predict landslides using various instruments and image analysis techniques, (2) methodological mechanics in using optical and microwave sensing, and (3) quantification of surface geological and geotechnical changes using 2D images. Recently, studies have shown that the degree of hazard is mostly influenced by speed, type, and volume of surface deformation. Despite available techniques to process lidar and image/radar-derived 3D geometry, prior works mostly focus on using 2D images, which generally lack details on the 3D aspects of assessment. Thus, assessing the 3D geometry of terrain using elevation/depth information is crucial to determine its cover, geometry, and 3D displacements. In this review, we focus on 3D landslide analysis using RS data. We include (1) a discussion on sources, types, benefits, and limitations of 3D data, (2) the recent processing methods, including conventional, fusion-based, and artificial intelligence (AI)-based methods, and (3) the latest applications. [ABSTRACT FROM AUTHOR]

This study investigates the interplay between particle shape, grading and initial sample density, three of the most important factors influencing the mechanical behaviour of sheared granular assemblies. Using the discrete element method (DEM), two-dimensional assemblies of varying initial sample density, particle aspect ratio, AR , and coefficients of uniformity, C u , were prepared and subjected to drained biaxial shearing until the critical state was reached. We assessed the interplay between each of these parameters by evaluating whether the effect of any given parameter on a mechanical quantity is influenced by any other parameter. Our analyses show that the effect of some of these key parameters on mechanical response, can indeed be influenced by other key parameters. The effect of the particle AR on the peak shear strength for the initially dense assemblies differs when compared with the medium-dense assemblies. The mechanical coordination number of the assemblies at the initial state correlates with the peak strength thereby explaining the interplay between particle AR and initial sample density on the peak shear strength. The linear relationship established between strength and dilatancy for a combination of all assemblies studied suggests that the strength-dilatancy relationship is a unique characteristic of granular assemblies. The dilatancy of the assemblies correlates strongly with the amount of contacts lost during shearing. The interplays found between particle shape, grading and initial sample density in this study show that to develop robust constitutive models for the prediction of granular material behaviour, the effects of multiple factors must be considered. [ABSTRACT FROM AUTHOR]

The advancement of remote sensing has enabled the creation of high-resolution Digital Elevation Models (DEMs). Topographic features such as slope gradient (SG), local convexity (LC), and surface texture (ST), derived from DEMs, are related to subsurface geological conditions. In South Korea, bedrock depth (Dbedrock) and the average shear wave velocity of soil (VSsoil) serve as metrics for determining the site class, which represents the degree of site amplification in seismic design criteria. These metrics, typically measured through geotechnical and geophysical investigations, require predictive methods for preliminary estimation over large areas. Previous studies developed an automatic terrain classification (AC) scheme using SG, LC, and ST, and subsequent research revealed that terrain classification effectively represents subsurface conditions such as Dbedrcok and average shear wave velocity down to 30 m depth. However, AC intrinsically depends on the regional features of DEMs, dividing regions based on nested means of topographic features (SG, LC, and ST). In this study, we developed two terrain classification methods to determine the thresholds of class divisions, aiming to optimize Dbedrock and VSsoil predictions: Sequentially Optimized Classification (SOC) and Non-Sequentially Optimized Classification (NOC). Through the study of the sensitivity of terrain classification methods, smoothing levels, and threshold levels for terrain class generation, we identified the best classification method by comparing it with the geological and mountainous region distribution. Subsequently, we developed DEM-dependent regression models for each class to enhance the accuracy of predicting Dbedrock and VSsoil. The main findings of this study are: (1) the terrain class map suggested in this study represents the distribution of alluvial plane and mountainous regions well, and (2) the DEM calibration for each class provides increased accuracy of Dbedrock and VSsoil predictions in South Korea. We anticipate that the terrain class map, along with Dbedrock and VSsoil maps, will be effectively utilized in geological interpretations and land-use planning for seismic design. [ABSTRACT FROM AUTHOR]

Geomorphometric analysis provides crucial insights into the hydrological characteristics by delineating the land-surface features of a drainage basin. The study focused on analyzing the geomorphometric parameters of the Montenegrin segment of the Ibar River drainage basin using the ALOS Global Digital Surface Model 30 m (AW3D30). Geomorphometric parameters, covering linear and areal parameters, were computed using standard mathematical formulas in LibreOffice Calc software and hydrology tools in commercial GIS software ArcGIS, as well as open-source software QGIS with SAGA GIS modules. Results reveal a dendritic pattern in the stream network, with an inverse relationship between stream length and order, and an elevated bifurcation ratio indicating heightened vulnerability to flooding, influenced by geological, geomorphological, and climatic factors. Furthermore, examination of diverse areal morphometric parameters, such as drainage density, stream frequency, form factor, circularity ratio, and elongation ratio, unveils the hydrological dynamics of the Ibar basin. This characterization illustrates the region as possessing high permeability and dense vegetation cover, suggesting vulnerability to erosion and consequent effects on water and sediment discharge. Additionally, this study underscores the significance of user-defined parameters in geomorphometric modeling, particularly in selecting algorithms within analysis software, which significantly impact drainage basin parameters. [ABSTRACT FROM AUTHOR]

To simulate the creep characteristics of corn straw particles under uniaxial compression, a 6-level 2D model was created using PFC 2D software according to the actual uniaxial creep test, the grain size, and shape of corn straw particles. Five groups of controlled tests were designed by the control variable method to study the influence of Maxwell body parameters Em, m; Kelvin body parameters Ek, k; and friction coefficient f on the creep curve of Burgers model. Results revealed that the creep characteristics of corn straw are affected by these 5 parameters. After multiple debugging by trial-and-error method, simulation parameters suitable for describing the creep characteristics of corn straw particles were obtained. The creep curves obtained by simulation under these parameters are consistent with those obtained by physical tests. It was shown that PFC software can not only study the creep characteristics of geotechnical materials, but also study the creep characteristics of agricultural fiber materials, which provides a reference for the subsequent rheological characteristics of biomass materials. [ABSTRACT FROM AUTHOR]

Extracting a channel network based on the Digital Elevation Model (DEM) is one of the key research topics in digital terrain analysis. However, when the channel area is wide and flat, it is easy to form parallel channels, which seriously affect the accuracy of channel network extraction. To solve this problem, this study proposes a method to identify and eliminate parallel channels extracted by classical methods. First, the channel level in the study area is marked based on the flow accumulation data, and the parallel channels are then identified using the positional relationship between the different channel levels. Finally, the modification point of the identified parallel channels is determined to eliminate the parallel channels, with the help of the change relationship between the parallel channel and its upper-level channel. In this study, two watersheds in southeast China are selected as examples for method verification and analysis. Experimental results show that the parallel channel identification method proposed in this paper can accurately identify all parallel channels and eliminate the identified parallel channels one by one. The location relationship of the modified channels is consistent with the actual situation, indicating that the proposed method has good application potential in DEM-based channel extraction networks. [ABSTRACT FROM AUTHOR]

The slope calculation algorithm is one of the most widely used geospatial algorithms employing the 3x3 moving window technique (along with calculation of aspect, curvature and flow direction). This work presents an approach consisting of transforming a slope algorithm from a sequential form into a version that can exploit vector and parallel traits of multicore architectures with vector instructions. This approach allows us to take advantage of the potential of the modern multicore processors. The basic idea for optimizing the 3x3 moving window computation is to split the equation used to calculate the result into parts that operate on data that are known to exist in adjacent memory locations. The research was conducted on two multicore architectures without the change in the code — the older architecture was Sandy Bridge and the newer one was Haswell (with more cores). The efficiency of the developed slope algorithm was verified in practice with the use of DEM files of the same resolution but of different sizes. We showed through the numerical experiments that our approach gives better time performance than the original algorithm (and other tools) — and with no loss of accuracy. [ABSTRACT FROM AUTHOR]

To improve the effectiveness of fracturing treatment, it is vital to understand how multiple fractures interact with each other. This study presents a fully coupled hydraulic fracture model that considers both Newtonian fluids and power-law fluids to investigate the effect of stress shadowing in different propagation regimes, from toughness- to viscosity-dominated, under limited entry conditions. The dimensionless parametric space for a plane-strain fracture driven by power-law fluids is outlined, and numerical analysis is performed in the parametric space to simplify the problem. Moreover, the numerical scheme for the coupled hydromechanical problem is verified by comparing the results to the existing analytic solutions. It is shown that the simultaneous propagation of multiple fractures is significantly influenced by the fracture propagation regime and cluster spacing. Fractures tend to grow uniformly in the viscosity-dominated regime, and the fracture reorientation can be observed if both the cluster spacing and stress anisotropy are small. In contrast, fractures propagating in the toughness-dominated regime tend to propagate in the opposite direction of the adjacent fractures to avoid each other, resulting in minimal overlap between fracture lengths. The influence of fracture propagation regime is consistent for Newtonian and power-law fluids. Additionally, as the cluster spacing increases, the effect of stress shadow decreases, and the behavior of each individual fracture resembles that of an isolated fracture. Highlights: A fully coupled hydraulic fracture model for studying the simultaneous growth of multiple fractures driven by Newtonian and power-law fluids is developed. A dimensionless parametric space for a plane-strain fracture driven by power-law fluid is established. The effect of fracture propagation regimes and cluster spacing on the simultaneous growth of multiple fractures is revealed. [ABSTRACT FROM AUTHOR]

The popularity of sports and recreational receivers of the global navigation satellite systems is steadily increasing and provides athletes, coaches, and scientists with a wealth of information on movement occurring both horizontally and vertically. Under mountainous conditions, considering the effort put in by the athlete as well as their safety, the elevation parameter appears to be particularly relevant. The aim of the study was to propose a methodology for assessing sports receivers in terms of their determination of the elevation component based on digital elevation models while paying attention to the appropriate measures for testing these devices. The methodology was applied for wrist-worn global navigation satellite systems' receivers used by the participants of an uphill running event. In terms of elevation determination, the most accurate three receivers (same model) were those supported by the barometric altimeter, in which the Root Mean Square result obtained ranged from 3.6 to 4.1 m. The majority of receivers underestimated the total elevation gain, the mean value of which was −3.8%, which does not appear to be affected by the reception of two global navigation satellite systems or the use of a barometric altimeter. The error characteristics were common within the group of receivers of a particular manufacturer. [ABSTRACT FROM AUTHOR]

AbstractSpherical and flaky particles are mixed during hard rock tunneling. In particular, flakey particles are difficult to load, resulting in conveying machines that have difficultly operating efficiently. Based on the characteristics of flakey particles and the present conveying structures, such as star wheels, three new conveying structures are introduced in this paper, and the parameters related to the conveying ability are evaluated with theoretical analysis. Then, the flow and trajectory of particles under different conveying structures and the difference in their working capabilities were investigated with the help of the discrete element method (DEM). Finally, conveying machines with different conveying structures are made with 3D printing technology and experiments for validation of the conveying ability are performed. The results show that the conveying structures can be divided into two categories: those with a rotational speed proportional to the loading rate and those with the opposite condition. The propulsion status has a stable loading phase with a long time period relative to the non-propulsion status. The findings can be used to guide conveying machine designs, and they can be helpful for the enhancement of the working ability in conveying particles with flakey shapes. [ABSTRACT FROM AUTHOR]

AbstractThe effect of Johnson–Kendall–Roberts (JKR) surface energy on the flowing property of fresh concrete was numerically studied. The fresh concrete was simplified into coarse aggregate and mortar, both described as the particles. The Hertz-Mindlin with JKR contact model was employed to describe the constitutive relationship of fresh concrete. The contact parameters were calibrated through experiment and numerical simulation of multiple flow tests. The impact of these contact parameters on the residual height (Hr) of fresh concrete after slumping was examined using a slump test. The significance degree of mortar–mortar contact parameters on the Hr was studied using an orthogonal test. The effect of the surface energy (γ) on the flow index (Bm) and flow time (Tv) of fresh concrete was studied intensively based on the L-box flow and V-funnel tests. The mortar–mortar contact parameters, γ and rolling friction coefficient (μr), most significantly impacted the Hr. The mortar–mortar surface energy (γm-m) significantly impacted Bm and Tv compared to the aggregate–mortar and aggregate–aggregate surface energies ((γa-m) and (γa-a), respectively). The effect of  γa-a, γa-m, and γm-m on Bm was interconnected. Under appropriate parametric values, the Bm was the most stable, and the workability of fresh concrete was the best. In addition, as γ  increased, Hr and Bm decreased and Tv increased. The flowability of the fresh concrete worsened. [ABSTRACT FROM AUTHOR]

The mapping of small-scale irrigation areas is essential for food security and water resource management studies. The identification of small-scale irrigation areas is a challenge, but it can be overcome using expert knowledge and satellite-derived high-spatial-resolution multispectral information in conjunction with monthly normalized difference vegetation index (NDVI) time series, and additional terrain information. This paper presents a novel approach to characterize small-scale irrigation schemes that combine expert knowledge, multi-temporal NDVI time series, multispectral high-resolution satellite images, and the random forest classifier in the Zamra catchment, North Ethiopia. A fundamental element of the approach is mapping small-scale irrigation areas using expert decision rules to incorporate the available water resources. We apply expert decision rules to monthly NDVI composites from September 2020 to August 2021 along with the digital elevation model (DEM) data on the slope, drainage order, and distance maps to derive the sample set. The samples were based on the thresholds obtained by expert knowledge from field surveys. These data, along with the four spectral bands of a cloud-free Planet satellite image composite, 12 NDVI monthly composites, slope, drainage order, and distance map were used as input into a random forest classifier which was trained to classify pixels as either irrigated or non-irrigated. The results show that the analysis allows the mapping of small-scale irrigation areas with high accuracy. The classification accuracy for identifying irrigated areas showed a user accuracy ranging from 81% to 87%, along with a producer accuracy ranging from 64% to 79%. Furthermore, the classification accuracy and the kappa coefficient for the classified irrigation schemes were 80% and 0.70, respectively. As a result, these findings highlight a substantial level of agreement between the classification results and the reference data. The use of different expert knowledge-based decision rules, as a method, can be applied to extract small-scale and larger irrigation areas with similar agro-ecological characteristics. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the impact of the particle shape of granular soil particles on the results of cone penetration test (CPT). The discrete element method (DEM) was used to model the CPT in soil particle samples in 3D. The influence of particle shape is studied by parameters of overall regularity (OR), which is obtained from different mixing ratios of the real shape particles and spherical particles. The real particle shapes are obtained from a 3D laser scanner for the simulations. The particle refinement method is applied to enhance computation efficiency. The cone resistance and sleeve resistance curves are smoothed by fitting equations. The factors of OR of soil, particle friction coefficient, particle roundness and initial porosity were demonstrated to have considerable influences on the cone tip resistance and sleeve resistance. The displacement field and the rotational field were plotted to study the microscopic behaviour of granular soils during the penetration process. [ABSTRACT FROM AUTHOR]

The discrete element method (DEM) is a numerical technique used in many areas of modern science to describe the behavior of bulk materials. Terramechanics of planetary soil analogs for in situ resource utilization activities is a research field where the use of DEM appears to be beneficial. Indeed, the close-to-physics modeling approach of DEM allows the researcher to gain much insight into the mechanical behavior of the regolith when it interacts with external devices in conditions that are hard to test experimentally. Nevertheless, DEM models are very difficult to calibrate due to their high complexity. In this paper, we study the influence of fundamental model parameters on specific simulation outcomes. We provide qualitative and quantitative assessments of the influence of DEM model parameters on the simulated repose angle and computational time. These results help to understand the behavior of the numerical model and are useful in the model calibration process. [ABSTRACT FROM AUTHOR]

The discrete element method (DEM) has become the numerical method of choice for analysing and predicting the behaviour of granular materials in bulk handling systems. Wet-and-sticky materials (WSM) are especially problematic, resulting in build-up and blockages. Furthermore, due to the large number of particles in industrial-scale applications, it is essential to decrease the number of particles in the model by increasing their size (upscaling or coarse graining). In this study, the accuracy with which upscaled DEM particles can model the discharge of a cohesive material from a belt conveyor onto an inclined impact plate was investigated. Experimentally, three sand grades (particle size distributions, PSDs) were used, each in a dry (non-cohesive) state and with three levels of moisture-induced cohesion. The effects of the modelled PSDs on the material flow, build-up on the plate, the peak impact force and the residual weight were investigated. Although a linear cohesion contact model was mostly used, the results were also compared to that of the Johnson–Kendall–Roberts (JKR) and simplified JKR (SJKR) models. It was found that the general profile of the pile (build-up) could be accurately modelled, but using a more accurate (but still upscaled) PSD improved the results. The impact force and the residual weight on the plate could be accurately modelled (error < 15 % ) if the particle size was not excessively scaled. The maximum acceptable scaling factor was found to be a geometric factor of the bulk measure of interest, and not a factor of the physical particle size. Furthermore, with an increase in cohesion, the bulk measures such as the thickness of the discharge stream and the height of the material build-up increased, which meant that the maximum acceptable scale factor also increased. The results are valuable for future accurate and efficient modelling of large industrial scale applications of WSMs. [ABSTRACT FROM AUTHOR]

A particle scale model based on a full two-way coupling of the Discrete Element Method (DEM) and Smoothed Particle Hydrodynamics (SPHs) methods is applied to SAG mills. Motion and collisions of resolved coarser particles within an SAG mill are performed by the DEM component. Fine particles in the feed combine with the water to form a slurry, which is represented by the SPH component of the model. Slurry rheology is controlled by solid loading and fine particle size distribution for each volume of slurry. Transport, dispersion, and grinding of the slurry phase particle size distribution are predicted by solving additional coupled advection–diffusion equations in the SPH component of the model. Grinding of the finer particles in the slurry due to collisions and shear of the coarser particles (rocks and grinding media) is achieved via the inclusion of population balance terms in these equations for each SPH particle. This allows prediction of the transport of both coarser and finer material within the grinding and pulp chambers of an SAG mill, including the discharge performance of the mill. This particle-scale model is used to investigate the relative performance (throughput, product size distribution, resident particle size distribution, net power draw, wear) for an SAG mill at a pilot scale and a 36 ft industrial scale. The 36′ SAG mill considered is a geometrically scaled-up version of the 1.8 m Hardinge pilot scale mill but with a longer belly length, reflecting current SAG mill design preferences. The belly lifters are scaled to a lesser degree with a larger number of lifters used (but still many fewer liners than would typically be used in a large SAG mill based on conventional liner selection rules). The model shows that despite reasonable qualitative similarities, many aspects of the charge structure, slurry transport, coarse particle and slurry discharge through the grates, and the collision energy spectra vary in important ways. This demonstrates that a near purely geometric scale-up of an SAG mill is not sufficient to produce a comparable performance at the two physical mill scales. [ABSTRACT FROM AUTHOR]

This study was undertaken in the Himalayan basin, in the river Lohawati, Uttarakhand, to study its hydro-morphological characteristics and prioritise the watersheds using geospatial tools. Advanced Spaceborne Thermal Emission and Reflection (ASTER-30 m) data and the Survey of India's topographic sheets were used to analyse the study area comprehensively. Nine watersheds were identified within the basin in order to calculate the hydro-morphological characteristics in terms of basic, shape, texture, and relief aspects. The basin was identified as being elongated, with a total drainage area of 337.48 km2. The interaction between the terrain, rock formations, and precipitation levels produced a branching structure in the areas drainage system that ranged from dendritic to sub-dendritic. The basin had been classified as a fifth-order basin, comprising a network of 500 stream segments spanning a total length of 492.41 km. In each of the watersheds, the primary streams are of the first order, followed by those of the second order, and so forth. The physiography and lithology of the basin have a significant influence on this pattern. The calculated elongation ratio, circulatory ratio, form factor, shape index, and shape factor ranged from 0.57 to 0.80, 0.35 to 0.64, 0.26 to 0.50, 1.98 to 3.89, and 0.57 to 1.77, respectively. These values indicate that watersheds are elongated, suggesting moderate lag times. The parameters, including drainage density (0.98 to 1.62), stream frequency (1.07 to 1.59), infiltration number (1.04 to 2.59), drainage texture (0.67 to 2.82), and drainage intensity (0.93 to 1.12), pointed towards the coarser drainage texture, higher infiltration, and minimal runoff characteristics of the basin. In light of the relief characteristics of the basin, a higher basin relief, relief ratio, and relative relief were observed for the watersheds, indicating the possibility of higher erosion and deforestation rates. Using the Weighted Sum Analysis (WSA) method, the computed factors were utilised to rank the watersheds based on their potential for erosion. Based on the WSA approach, watersheds were classified into high-, moderate-, and low-prioritisation zones. This further indicates that 36.14% (121.95 km2) of watersheds are in the high-priority zone, and that 48.84% (164.91 km2) and 15.00% (50.62 km2) of watersheds are in the moderate- and low-priority zones, respectively. The WSA is a practical strategy to prioritise watersheds when making appropriate decisions. [ABSTRACT FROM AUTHOR]

The mechanical properties of wheat grains were measured and analyzed using discrete element software, which provided crucial data for their processing in a mill. The foundational Hertz–Mindlin model was used as a theoretical framework to evaluate the accumulation angle of wheat grains. The Plackett–Burman, steepest ascent, and Box–Behnken methods were utilized in a series of experiments, with the accumulation angle serving as the dependent variable. Targeting the actual angle of repose in the response surface, the optimal parameters were derived using the regression equations. These included a static‐friction coefficient of 0.3 between individual wheat grains, rolling‐friction coefficient of 0.04 for wheat–wheat interactions, static‐friction coefficient of 0.554 for wheat–tooth roller interactions, collision recovery coefficient of 0.5 for wheat–wheat collisions, collision recovery coefficient of 0.45 for wheat–tooth roller collisions, and rolling‐friction coefficient of 0.05 for wheat–roller interactions. Relying on the bonding contact model of Hertz–Mindlin, virtual uniaxial compression tests were conducted to calibrate the wheat grain bonding parameters. A regression equation for the critical load was subsequently generated using the critical load of the wheat grain bonding model as the response variable. The optimal parameters were calculated and incorporated into the EDEM model for computation, which resulted in a relative error of 1.6% between the calculated and observed values, confirming the accuracy and feasibility of the calibration method, suggesting that the calibrated parameters were accurate. [ABSTRACT FROM AUTHOR]

Tight gas sandstone reservoirs play an important role in the field of exploration and development of unconventional oil/gas resources. However, these reservoirs typically exhibit low-porosity and poor-permeability, with pore structures of strong heterogeneity comprising connected and isolated pores. The traditional rock physics models (such as the Gassmann model) are established under the assumption of fully connected pores, which cannot reasonably describe the complexity in tight reservoirs. In this regard, this work proposes a rock physics modeling approach aimed at tight sandstone reservoirs based on a reformulated Xu–White model. Specifically, the differential effective medium model and Xu–White model are combined to analyze the influences of isolated pores on the dry rock skeleton. To characterize the general effects due to the different pore types on rock elastic moduli, the volume content of connected pores is defined as a pore-connectivity parameter. The simulated annealing algorithm is applied to invert the parameter, which is treated as a weighting coefficient for correcting the wet rock elastic moduli, thereby improving the precision of rock physics modeling. The proposed approach is tested and verified by using the log data of the work area of Sichuan Basin, West China. The result shows that, compared with the conventional method, the P- and S-wave velocities predicted by the proposed method are consistent with the log data. In addition to the inversion results of the conventional petrophysical parameters, the inverted pore-connectivity parameter can be a good auxiliary attribute that assists locating potential targets for tight gas sandstone reservoirs. [ABSTRACT FROM AUTHOR]