Search Results (471)

This two-year study proposes the application of industrial computed tomography (CT) as a complementary technique to conventional capacity and internal resistance measurements for evaluating not only the state of health (SOH) of different lithium-ion battery types used in electric vehicles, but also to predict its past. While commonly used assessment methods primarily focus on electrical properties of batteries, industrial CT allows non-destructive, three-dimensional visualization and systematic evaluation of internal structural changes within individual battery cells and allows to compare different lithium battery type internal structure changes. The study investigates two lithium-ion battery chemistries: lithium iron phosphate (LFP) and nickel manganese cobalt oxide (NMC). The effects of different discharge rates (1C, 2C, and 3C) on battery degradation were analyzed by comparing CT scan data obtained for the cells in their initial (new) condition and after reaching 60% SOH following cycling-induced aging. The findings provide improved understanding of the physical processes associated with battery aging under varying discharge conditions, enabling a more complete evaluation of battery health. Full article

Water–bearing fractures and seepage–prone zones ahead of tunnel faces may evolve rapidly under excavation–induced disturbance, making early identification and process tracking essential for risk mitigation. Cross–hole electrical resistivity tomography (ERT) is sensitive to fluid–controlled conductivity contrasts, but time–series interpretation based on independently inverted snapshots is often unreliable due to ill–posedness, noise, and temporal inconsistency. In this study, we propose an improved time–lapse ERT inversion framework for monitoring evolving water–bearing fractures ahead of tunnels. The method is formulated as a baseline–anchored, Occam–consistent difference inversion that directly estimates resistivity changes relative to an initial state, incorporating error–aware weighting of differenced data and anisotropic regularization adapted to cross–hole sensitivity, so that temporal coherence is enforced during inversion rather than through post hoc differencing. Synthetic verification is conducted using three dynamic scenarios representing horizontal, vertical, and diagonal migration of conductive water–bearing pathways between boreholes. Quantitative comparison against independent inversion across all scenarios and time steps demonstrates that the proposed framework substantially reduces the root mean square error and mean relative error of the recovered resistivity, while significantly improving the spatial correlation coefficient between the recovered and true models, with the largest improvements observed in the diagonal–migration scenario. The reconstructed change maps exhibit more compact anomaly geometry and delineate evolution corridors aligned with the prescribed trajectories, whereas independent inversion produces diffuse and epoch–dependent change patterns. These results indicate that the proposed time–lapse inversion framework provides a more reliable basis for interpreting evolving seepage–related conductive structures in tunnel–ahead investigations. Full article

Seepage failure is a primary cause of reservoir dam breaches. Conventional monitoring cannot reveal leakage paths across the dam, and static surveys miss weak-zone evolution. To address these challenges, this study constructs a typical geoelectric numerical model of low-resistivity expansion at a dam abutment. It systematically analyzes the response characteristics of apparent resistivity, independently inverted resistivity, and time-lapse resistivity imaging to the seepage failure process and validates the method through physical model tests and field observations. Inverted resistivity delineates hazards better than apparent resistivity, especially for small targets. Using the initial non-leakage model as a baseline, the resistivity-change profile obtained by ratio processing reveals the development trend of the hazard. Time-lapse inversion suppresses spurious artifacts from independent inversions and images the gradual expansion of the seepage weak zone. The L1-norm-constrained differential inversion further improves the convergence of the low-resistivity region and the accuracy of the anomaly center. Physical tests show rising water level reduces resistivity, especially in leakage-prone areas. Field tests show that after grouting, deep resistivity increases while shallow resistivity decreases. The results demonstrate that the time-lapse differential inversion algorithm based on the L1 norm accurately captures the spatiotemporal evolution of leakage hazards in earth-rock dams, providing reliable technical support for reservoir safety monitoring and evaluation. Full article

In central Mexico, ground failure and subsidence have accelerated, as evidenced by the Villa de Reyes graben, particularly at the El Hundido Dam, with the primary cause attributed to groundwater overexploitation. This study integrates electromagnetic profiling (EMP), electrical resistivity tomography (ERT), and transient electromagnetic (TEM) surveys to determine the origin of the fractures at the El Hundido Dam. Based on the TEM survey, a geoelectric section was obtained that models the depth and morphology of the igneous bedrock. At the El Hundido Dam, the igneous basement exhibits convex deformation due to transpressional stresses, which favours the formation of a positive flower-type fault structure. Deformations caused by the basement topography and the fault system are evident in the 100 m-thick Quaternary sequence, as revealed by ERT studies. ERT and EMP surveys showed the presence of a clayey layer that acted as a barrier to surface water infiltration, allowing it to be stored in the past, and which is now destroyed by fractures. Although the drop in the water table has contributed to polygonal cracking, hydro-compaction, and ground subsidence, local tectonics is the primary factor controlling subsoil faulting at the El Hundido Dam. Full article

The hyporheic zone (HZ) mediates biogeochemical exchanges between rivers and aquifers, yet its spatial and temporal dynamics in large, regulated rivers remain poorly characterized due to limitations of point-based measurements. Here, we combined three time-lapse electrical resistivity tomography (T-ERT) surveys with continuous hydrological and hydrochemical monitoring along a meandering reach of the lower Yellow River, generating a two-dimensional, profile-integrated view of HZ geometry under three hydrodynamic states: low flow (1 December 2020), natural rising stage (1 March 2021), and peak stage during the Xiaolangdi (XLD) water-and-sediment regulation (1 July 2021). Absolute tomograms identified two hydrostratigraphic units: an upper sandy-silt cap (35–170 Ω·m) and an underlying sand aquifer (12–35 Ω·m). Percent-difference tomograms, relative to the low-flow baseline, revealed lateral HZ expansion from ~15 m and vertical growth of 2.5 m at the rising stage to ~36 m and 4.5 m at peak stage, with local resistivity decreases exceeding 38%. In contrast, the deeper mixing zone varied by <10% across surveys. Temperature, rainfall infiltration, and groundwater freshening could not explain the observed patterns. These results were corroborated by three independent lines of evidence: lateral conductivity excursions and in-well temperature records at floodplain well W2, and analytical Darcy–Archie calculations, all consistent with the predicted lateral extent and mixing fraction. River stage, amplified by the XLD release, emerged as the dominant control on two-dimensional HZ geometry. This study provides direct empirical evidence of hyporheic dynamics in a large regulated river and demonstrates that T-ERT, supported by sparse hydrological data, offers a minimally invasive and effective tool for characterizing hyporheic zones. Full article

With the increasing development of underground spaces adjacent to urban levees, contact seepage frequently occurs at the interface between the soil and underground structures. However, traditional geophysical detection methods are often rendered ineffective in such environments due to spatial restrictions and detection blind spots. To address these challenges, this paper proposes a vertical-array lateral scanning detection method. This approach utilizes electrical resistivity tomography (ERT) with flat-base electrodes and ground-penetrating radar (GPR) to acquire data directly from vertical wall surfaces. The feasibility of this method is validated through numerical simulations and field data. The results indicate that the proposed method effectively overcomes the high-resistance shielding effect of hardened walls and clearly reveals the electrical structure of the soil behind the wall. Specifically, the contact seepage zone manifests as a layered low-resistivity feature immediately adjacent to the wall, while the penetrating leakage channel presents as a continuous low-resistivity anomaly extending from the contact interface deep into the levee body. These findings confirm the applicability of this technology for the qualitative identification and effective detection of hazards in complex, space-restricted urban environments. Full article

The Devene fault system, a major strike–slip structure at the boundary between the Balkan Range and the Moesian Platform in NW Bulgaria, remains a subject of debate regarding its Quaternary activity. This study investigates the shallow expression of the fault at two representative sites, Tri Kladentsi and Beli Breg, using high-resolution electrical resistivity profiling to differentiate tectonic deformation from climatically driven landscape evolution. At Tri Kladentsi, resistivity profiles confirm a steeply dipping structural boundary within the Miocene bedrock, juxtaposing limestone against sands. The overlying 25 m thick loess cover, however, remains sub-horizontal and undisturbed. Likewise, at Beli Breg, the complex architecture of stacked channel sequences and tributary deposits at the Ogosta River confluence reveals no identifiable fault displacement. Our results suggest a high degree of morphological mimicry, where asymmetric river valleys produced by selective erosion and differential loess accumulation superficially converge with tectonic signatures. The long-term left-lateral slip rate is estimated at 0.14–0.19 mm/yr based on a 20 km Miocene offset. Nevertheless, the lack of modern surface rupture indicates a deceleration of the fault slip rate and a transition to a buried fault top during the Quaternary. These findings necessitate a re-evaluation of regional seismic hazard assessments, because the absence of continuous surface traces physically constrains the maximum earthquake potential. Full article

The imaging quality of electrical resistivity tomography (ERT) crucially depends on the electrode array configuration. Although the symmetrical optimized ‘Compare R’ (CR) method improves computational efficiency, restricting the search to the symmetrical data set inherently limits the imaging accuracy. To address this limitation, this paper proposes a multi-step optimized CR method that progressively explores both symmetrical and asymmetrical arrays to extend the search space and further enhance imaging accuracy. Numerical experiments demonstrate that the multi-step optimized array yields the highest average relative model resolution (0.646) and structural similarity index measure (0.668), surpassing the symmetrical optimized array (0.615 and 0.630, respectively). Field experiments on pipeline detection confirm that the proposed array accurately identifies the location and geometry of underground anomalies and achieves superior imaging accuracy. Applications in karst cavity exploration further confirm that the proposed array effectively detects the deep karst caves and the bedrock interfaces, as validated by borehole drilling. Additionally, the detection performance of both optimized arrays is evaluated at different depths. The results indicate that the multi-step optimized array preserves anomaly geometry and resistivity more reliably at greater depths, attributed to the accumulation of asymmetrical data points in deep regions, which results in a significantly higher data density. Full article

Electrical resistivity tomography (ERT) serves as an auxiliary tool for marine engineering geological investigation. Through modeling, the effectiveness of this method was evaluated in areas affected by hydrological and underwater environmental changes, with a focus on the submarine geological structure in nearshore environments. The effects of pore water mineralization and cation exchange capacity on the resistivity of seabed sedimentary layers were investigated via rock physics modeling, and the corresponding relationship curves were obtained. Physical simulation experiments were also conducted to validate the rock physics modeling results. This process quantitatively analyzed the factors influencing the resistivity of nearshore seabed sediments, obtained the resistivity of each sedimentary layer, and interpreted the causes of resistivity variations. Resistivity models of different terrains were established for sandy clay seabed sediments with varying water salinities. The innovative use of submarine electrical resistivity tomography was proposed, and its feasibility and advantages were confirmed through numerical simulations. Field tests along the Baltic Sea coast demonstrated that, compared with previous methods, submarine electrical resistivity tomography offers higher resolution and improved exploration performance. Full article

Data acquired from a processing system using industrial-scale electrical resistance tomography (ERT) could provide valuable information on the operational performance of hydrocyclones. Tomography images of hydrocyclones, in general, are used to analyze operational parameters, but their analysis may not be fast enough to capture transient changes or provide clear phase boundaries between the object of interest and the medium. In such cases, one of the alternative approaches is to utilize least-squares modeling of the raw data to interpret transient changes, which is relatively faster and more efficient. In hindsight, this method may not be able to identify the location of the object of interest. In this paper, a new data analysis approach to estimate transient changes in the disturbance and a simplified conductivity matrix to estimate the location of the disturbance are considered. The conductivities measured across a cross-section were used to calculate the size of the disturbance. The disturbance’s position with respect to the cross-section was estimated using a simplified reconstruction of the conductivity matrix. In both cases, the same conductivity matrix was used. Several fundamental ERT experiments with different disturbance sizes were carried out to establish a suitable algorithm that could identify the disturbance. The analysis method presented in this paper can provide a basis to further explore an additional approach to analyze the performance of the hydrocyclone. The estimated radius of the disturbance was overlaid on an actual cross-section to infer the position with respect to the cross-section of the system. An attempt was also made to develop an empirical relationship that can estimate the effective size of the disturbance. The paper also discusses some implementation and practical challenges that need to be addressed for us to gain confidence in the proposed analysis method. Full article

Artificial levees along major rivers are critical for flood-risk mitigation, yet many aging structures have poorly constrained internal composition and material heterogeneity, limiting the reliability of conventional safety assessments. This study develops a quantitative, non-destructive framework for characterizing levee internal structure by integrating electrical resistivity tomography (ERT) with borehole (BH) observations. ERT profiles were combined with borehole measurements of grain size (D50) and water content to investigate subsurface compositional variability and to evaluate relationships between sedimentological and geophysical parameters. Grain-size data from borehole samples were modeled using four predictive approaches—random forest regression (RFR), artificial neural networks (ANN), linear regression (LR), and support vector regression (SVR)—based on ERT-derived resistivity and moisture information. The results reveal pronounced internal heterogeneity within the investigated levees and demonstrate consistent relationships between sediment composition, water content, and electrical resistivity. Among the tested models, the ensemble-based RFR provided the highest predictive performance (R² = 0.81). These findings indicate that D50 characteristics of levee materials can be reliably inferred from ERT data using machine learning, reducing the need for destructive sampling. The proposed approach offers a transferable methodology for levee assessment and supports future applications in non-destructive monitoring, spatially explicit flood-risk analysis, and climate-resilient flood-protection management. Full article

Accurately characterizing the kinematics of slow-moving urban landslides remains a major scientific and operational challenge, because no single monitoring technique can simultaneously provide spatially continuous deformation patterns and reliable three-dimensional displacement measurements. This study investigates the spatial and temporal evolution of a slow-moving landslide affecting the University of Azuay campus in Cuenca (Ecuador), where ongoing ground deformation has caused structural damage to several buildings. An integrated monitoring strategy combining GNSS measurements, Sentinel-1 multi-temporal DInSAR analysis, and geophysical investigations (ERT and seismic profiling) was adopted to characterize landslide kinematics and constrain subsurface conditions. GNSS observations revealed that the north–south displacement component was dominant, with cumulative displacements exceeding 20 cm during the monitoring period (from July 2021 to June 2024), while east–west displacements were on the order of 10 cm. MT-DInSAR analysis delineated the spatial extent of the unstable area and identified mean deformation rates of up to approximately −1.5 cm/year in the central sector of the landslide. The combined interpretation of geodetic and geophysical data indicates that slope instability is controlled by saturated fine-grained layers and mechanical contrasts, with the basal sliding zone associated with weak levels of the Mangan Formation. Overall, the results demonstrate the value of a multi-sensor, component-wise monitoring strategy for improving the reliability of deformation estimates and for supporting landslide risk assessment and land-use planning in complex urban environments. Full article

The northern Vietnam shelf, particularly the area adjacent to the Red River Fault Zone, is characterized by complex geology and active neotectonics. However, the patterns of degassing and the origins of hydrocarbon gases in this region remain poorly understood. In particular, the potential links between deep-seated fluid migration, fault systems, and gas anomalies in island groundwater systems have not been systematically investigated. This study presents preliminary results of dissolved methane, its homologues (C₂–C₅), helium, hydrogen, and carbon dioxide measurements in groundwater from Co To Island (Northern Vietnam), with the aim of identifying gas origins and assessing structural controls on fluid migration. A significant methane anomaly was discovered, with concentrations reaching up to 10% by volume in the northwestern part of the island. The hydrocarbon homologous series is traced up to pentane (C₅), and CO₂ content is also elevated, with a maximum of 5.4%. The average He concentration of 10.8 ppm significantly exceeds atmospheric equilibrium values, with maximum recorded concentrations of 18 ppm for He and 34.5 ppm for H₂. Stable carbon isotope analysis of methane (δ¹³C-CH₄ values ranging from −50.2‰ to −49.7‰ VPDB), combined with the presence of a complete C₁–C₅ hydrocarbon series and elevated mantle/crustal tracers (He, H₂), indicates a predominantly thermogenic/metamorphogenic origin for the gases, ruling out a purely biogenic source. The spatial distribution of anomalies is structurally controlled, closely associated with the NE-SW trending Co To Fault system and its intersections with subsidiary faults, as corroborated by recent electrical resistivity tomography data. These findings indicate intensive, focused gas leakage from a deep-seated source, likely related to thermogenic/metamorphic processes and active fault-mediated degassing. The results highlight the significant hydrocarbon potential of the region and underscore the critical role of neotectonic activity in controlling fluid migration pathways in island aquifer systems. Full article

Today’s fluvioscape of the Hessische Ried (Upper Rhine Graben) is the consequence of human intervention on the natural drainage system that has transformed a large floodplain into an intensively used cultural landscape. Already, the Romans carried out river regulation and water management to guarantee the transportation of material and troops, securing the territory of the Roman Empire. To secure the so-called Rhein-Limes, burgi (fortlets) were constructed along small tributaries of the River Rhine under Valentinian I. (364–375). The burgus at Trebur-Astheim represents such a military site. It is located at the Schwarzbach/Landgraben fluvial system, which was actively used as a waterway and connected important military sites such as the castra “Auf Esch” (Groß-Gerau) with the River Rhine and, thus, with the provincial capital Mogontiacum (Mainz). Using a combination of magnetic gradiometry, frequency domain electromagnetic induction (FDEMI), electrical resistivity tomography (ERT), direct push-sensing (DP), and sediment coring, we were able to detect a 15 m wide and 2.5 m deep Roman canal between the burgus at Trebur-Astheim and the River Rhine, opening the Hessische Ried hinterland to wider trade routes. Radiocarbon dating further reveals that after a final re-excavation, the channel started to silt up in the 7th/8th century AD and finally fell out of use. This last period of use may be associated with the activities of the Carolingian Königspfalz (royal palace) Trebur. Our study shows that the fluvioscape of the Hessische Ried dates back to Roman times and that the canal at Trebur-Astheim is one of the few navigable canals known to have existed north of the Alps during the Roman period and the Early Middle Ages. Full article

Retinal vein occlusion (RVO) is a common vascular disease that leads to vision loss due to macular edema (ME). This study investigated the role of autotaxin (ATX), a lysophospholipase D, in the pathogenesis of RVO. In mice, RVO was induced by intravenous administration of rose bengal followed by laser irradiation of retinal veins. ATX expression in the retina was evaluated using immunohistochemistry. Intravitreal ATX was administered, and retinal changes were assessed using fluorescence angiography and optical coherence tomography (OCT). In human retinal microvascular endothelial cells (HRMECs), intercellular barrier function was evaluated using transepithelial electrical resistance (TEER). In the murine RVO model, the ATX inhibitor HA130 was administered intravitreally, and retinal thickness was measured and compared using OCT. ATX expression was increased in retinal vessels in the RVO model. Intravitreal administration of ATX induced retinal edema and serous retinal detachment (SRD). ATX significantly disrupted the barrier integrity of HRMECs and promoted the expression of vascular endothelial growth factor (VEGF), which was ameliorated by HA130. Intravitreal administration of HA130 significantly reduced retinal thickening caused by retinal edema secondary to RVO and the elevated expression of intercellular adhesion molecule (ICAM)-1 in the retina. These findings suggest that ATX plays a critical role in RVO-induced ME by disrupting endothelial barrier integrity, potentially through the upregulation of VEGF in retinal endothelial cells and subsequent ICAM-1 upregulation in the retina. Full article