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Ground Penetrating Radar (GPR) systems mounted on Unmanned Aerial Vehicles (UAVs) are becoming a promising solution to inspect beneath the soil surface. In particular, resorting to Synthetic Aperture Radar (SAR) techniques, these systems are able to retrieve subsurface radar images, in which buried targets can be detected. However, one of the major bottlenecks of this technology is the significant amount of time required for computing the radar images (due to the usage of computationally expensive algorithms to handle non-regular acquisition domains). To face this challenge, this work proposes an efficient interpolation approach, combining a height shift operation with a 2D interpolation, that enables the adoption of a migration algorithm called Phase Shift Migration (PSM). As a result, the processing time is drastically improved, offering close to real-time operation. The proposed methodology has been validated in a realistic scenario for detecting buried explosive targets, comparing it with conventional backprojection techniques in terms of image quality and processing time. [Display omitted] [ABSTRACT FROM AUTHOR]

Herein we developed an education game based on a spreadsheet- activity and virtual reality (VR) for teaching the fundamentals of gasification and combustion. The game could be used as a valuable resource to motivate students at the undergraduate and senior high school level to consider economic and environmental assessment including sustainability concerns as they design a hypothetical chemical product or process. The proposed game is intended to be incorporated into any sustainability course design or chemical engineering course. The game is suitable for both chemistry majors and non-chemistry majors as it introduces fundamental energy changes in chemical reactions and design principles. Additionally, the game can be adapted for high school outreach activities. The game is freely available and encourages students to think critically while considering several factors in making key industrial decisions about a product or process. Factors considered include the water availability, socioeconomic impact, environmental impact, and proximity of technological location to infrastructures. The game is designed to raise awareness about hydrogen as an energy carrier, including its economic aspects and its wide range of industrial applications. It could also be used as a means of recruiting students into chemical sciences and engineering degree programs. • An education game based on spreadsheet- activity and virtual reality (VR) was developed. • The game could be used to teach economic and environmental assessment of hydrogen production. • The proposed game is intended to be incorporated into any sustainability course • Game encourages students to think critically while considering several factors in making key industrial decisions [ABSTRACT FROM AUTHOR]

• Integrated approach for multi-scale and multi-resolution diagnostics of wall paintings by the combination of wave-based and optical techniques. • Surface and subsurface investigation for the stratigraphic reconstruction of past intervention and modification. • For the first time, the microwave reflectometry is here proposed in combination with digital holographic speckle pattern interferometry for wall paintings inspection. • Proof of concept of the proposed tool on the wall paintings masterpiece of Masolino, Masaccio and Filippino Lippi in the Brancacci chapel in Firenze. Based on the analysis of the renaissance wall paintings by Masaccio, Masolino, and Filippino Lippi in the Brancacci chapel in Firenze, this paper discusses the use of complementary non-destructive techniques based on microwave and optical methods for the characterization of the structural integrity of the wall paintings and their support in masonry. The selected non-destructive techniques are the InfraRed Thermography (IRT), Ground Penetrating Radar (GPR), Microwave Reflectometry (MWR), and Digital Holographic Speckle Pattern Interferometry (DHSPI). In particular, the paper analyses the in-situ applicability of these techniques for the identification of the sequence of past interventions during centuries (stratigraphy analysis) and decay phenomena and defects, such as out-of-plumb or swelling area/elements, detachments, cracks and voids inside the wall. The results are compared with data obtained by means of consolidated techniques and methods, such as the Photogrammetry (performed by Structure from Motion method) and knocking test. The last one is normally used by restorers and conservators to recognize the presence of detachments. The proposed diagnostic strategy provides a survey from large scale by means of imaging techniques, to small scale increasing the spatial resolution thanks to the scanning of the surface by means of spot techniques. Therefore, the macroscopic survey of wall paintings was carried out using photogrammetry, in order to also provide metric information, to quantify the sizing out-of-plumb and swelling of the masonry or to locate of cracks, and followed by IRT. This preliminary morphometric survey was, supplemented by GPR, MWR and DHSPI for improve the results of the investigation. By combining these three techniques it was possible to inspect the entire thickness of the masonry (60-70 cm) with resolutions ranging from a few millimetres up to several centimetres. The combination of microwave-based and optical-based methods proved to be a valuable addition to routine methods for the holistic masonry diagnosis. Standard practice based on visual inspection and knocking test can be significantly improved and objectified by the proposed full-field, multi-sensor, multi-resolution approach. [ABSTRACT FROM AUTHOR]

In this study, we introduce a novel approach to determine root orientation from Ground Penetrating Radar (GPR) data, employing a dual-fitting strategy involving hyperbola fitting and polynomial regression surface fitting. The initial hyperbola fitting serves to capture essential parameters, while the subsequent polynomial regression surface fitting seeks to unveil nuanced relationships between root orientation angles and hyperbola characteristics. This dual-fitting framework represents a significant advancement in root analysis methodologies, offering a more refined and comprehensive understanding of root orientation derived from GPR data. [ABSTRACT FROM AUTHOR]

Hydrogen offers significant potential as a sustainable energy source. However, its storage and transportation pose challenges due to its volatility and low density. Subsurface geological formations, such as shale, sandstone, and coal, have been investigated as potential storage sites for hydrogen. Precise estimation of hydrogen adsorption in these formations necessitates a thorough understanding of kerogens, organic-rich sedimentary rocks prevalent in unconventional formations. In this study, we introduce a novel approach employing Extreme Gradient Boosting (XGBoost), Random forest (RF), Light gradient Boosting (LGBM), and Natural gradient boosting (NGBM) algorithms to intelligently predict hydrogen adsorption in various kerogen types. Among these, the NGBM algorithm, utilizing three input features (temperature, pressure, and kerogen types), demonstrated the highest predictive accuracy, achieving an R2 value of 0.989, RMSE of 0.062, and MAE of 0.037 for all data samples. SHAP diagram analysis identified kerogen types as the most influential parameter within the NGBM model. The presented approach has implications beyond energy storage, highlighting the significance of advanced technologies in addressing complex energy challenges. Precise hydrogen adsorption estimation in subsurface formations is vital for developing sustainable energy solutions, and our approach has the potential to expedite progress in this field. Interdisciplinary collaboration among geologists, chemists, and data scientists is crucial for devising innovative solutions for sustainable energy. [Display omitted] • Boosting machine learning method is effective for prediction hydrogen adsorption. • AI can be helpful for chemical processing. • Kerogen is potential for hydrogen adsorption. • The proposed workflow can be utilized in the assessment of underground hydrogen storage. [ABSTRACT FROM AUTHOR]

This paper presents a planar CPW-fed Ultrawideband (UWB) antenna with two independently tunable notch bands. The proposed design consists of a modified Rhombus-shaped monopole structure that is integrated with a dual band-stop filter based on hexagonal split ring resonators (HSRR). The antenna is capable of suppressing multiple frequency bands within ultrawideband range (3.1–11 GHz) such as WLAN and X-band downlink satellite communication frequency bands with an independent tunable mechanism to fulfill the on-demand band rejection. The frequency reconfigurability of the two notch bands is obtained by loading the hexagonal filter arms with two varactor diodes (for each band). Details of antenna design steps and reconfigurability mechanism are illustrated. The notch band element is explained using equivalent circuit model and surface current distribution at lower and higher notch frequency bands. A prototype of the proposed design is printed on the RO4003C (ϵ r = 3.55) substrate printed circuit board (PCB) and tested to authenticate the performance. The proposed antenna volume is 21.5 ▪ 48 ▪ 1.524 mm3 and demonstrates an omnidirectional radiation pattern in E and H planes with an average gain of 3.7 dBi across the operational passbands, while a sharp reduction in gain of -6.8 dBi and -3.5 dBi is achieved at the lower and higher notch bands, respectively. Continuous tuning is achieved experimentally from 5.08 to 5.77 GHz and 7.75 to 8.52 GHz for the lower and higher notch bands, respectively. Excellent agreement is observed between the simulated and measured results. Application areas include radio-frequency identifications, ground-penetrating radar, and wireless communications. [ABSTRACT FROM AUTHOR]

• The first geophysical investigations on a Pomor site on Svalbard were made. • Weak anomalies related to small contrast in dielectric constant of drifts and soil. • Near-surface stratigraphy studied based on reflectors down to ca. 2 m depth. • Below the thaw depth (ca. 2 m) no reflectors are present. • An approach to tackle climate change effects on cultural heritage sites in the Arctic. With climate warming, the cultural heritage sites of the Arctic are in great danger. Extensive research is needed to study such sites. The archaeological site at Russekeila – Kapp Linné, Svalbard was selected for the survey as previous research had highlighted its vulnerability to cryospheric hazards. The main objectives of the survey were (i) to register the precise surface and subsurface locations of cultural heritage (CH) (remains of an 18th century Russian Pomor trapper's hut) objects within the study area, (ii) to determine the impact of coastal erosion on the CH objects and (iii) to understand the near-surface stratigraphy of the site. The geophysical surveys were carried out using a Ground Penetrating Radar (GPR) instrument with two shielded antennas of 500 MHz and 800 MHz centre frequencies. Only weak anomalies were observed at the intersections with wooden drifts, which can be explained by the low contrast between the relative dielectric constant values of the driftwood and the background soil. The depth extent of the driftwood within the soil was understood from the processed GPR data to a depth of approximately 25 cm. A near-surface stratigraphy of the site morphology, including thaw depth, saturated and unsaturated sediments and soil cover, was established based on multiple reflectors observed to 2 m depth. Loose sediments are indicated by reflectors to a depth of approximately 20 cm. Unsaturated fine sediments, which show a stronger signal compared to the underlying saturated sand layers, can be observed from about 1.2 m depth. No reflectors are shown below the thaw depth. [ABSTRACT FROM AUTHOR]

• Novel flexible penetrometer for planetary regolith exploration is proposed. • Penetration model analysis and validation were conducted. • Principle prototype of the penetrator was developed and the system was verified. In-situ extraction of geological information from planetary subsurfaces is of great importance. To achieve this goal with low power consumption and deep penetration, a novel subsurface sounding system for planetary regolith exploration is proposed based on the operating principle of tape measures. Penetration model analysis and validation were conducted. The penetration mechanics of the penetrator head and body were modeled separately, and static penetration tests were performed to verify the feasibility of the penetrator and modify the penetration load model. As the structural design of the penetrator was completed, a cam-based impact clamping scheme was proposed. The impact system dynamics model was established to analyze the effect of pene-tration resistance and kinetic parameters on the penetration capability of the penetrator. The principle prototype of the penetrator was developed, and a load-free simulated planetary regolith penetration test system was built to verify the correctness of the design. This study may provide technical support for the future application of flexible detectors in planetary exploration. [ABSTRACT FROM AUTHOR]

On the Izu Peninsula of Japan, the Sagiriko fault group is located to the south of the Kita-Izu fault zone, which ruptured during the 1930 Kita-Izu earthquake (M jma = 7.3). A NS-trending strand of the Sagiriko fault group was ruptured during the 1930 earthquake, but conjugate EW-trending strands were not ruptured, and no Holocene activity on them has been documented. We surveyed the near-surface structure across the Sagiriko-b fault, one of the EW-trending strands, by ground penetrating radar profiling and radiocarbon dating of sediments obtained from two drilling cores. The results revealed a right-lateral displacement of 5.5 m of fluvial terraces around the survey site that formed after about 10 ka. The right-lateral slip-rate was calculated to be more than 0.55 mm/yr. This rate, which is significantly smaller than the crustal contraction rate in this area, suggests that the crustal contraction was probably spread across several EW-trending active faults parallel to the Sagiriko-b fault. [ABSTRACT FROM AUTHOR]

This paper proposes a new dual-band difference (DBD) method to retrieve total electron content (TEC) in Martian ionosphere with the dual-band echoes of the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS). It establishes the relationship between the group delay difference of two-band echoes and the plasmas frequency. Then the Martian ionospheric parameters are solved with this equation. Then the TEC is calculated by integrating the vertical distribution model of Mars electron density. This method is used to calculate the TEC of the typical ionosphere in the southern hemisphere of Mars, and the comparison with previous results validates this method. The experiments prove that this method can not only calculate the TEC of dayside and nightside in different periods, but also effectively eliminate the influence of ionospheric dispersion on radar echoes. Moreover, the time variation characteristics of the ionosphere are analyzed. According to the characteristics of this algorithm, the error sources are analyzed. By calculating the influence of different parameters on the results, it is proved that the maximum error of the algorithm is less than 0.1 TECU. [ABSTRACT FROM AUTHOR]

Heat extraction from the single-well geothermal heating system (SWGHS) is significantly restricted by the high thermal resistance of the surrounding host rocks. To improve heat production efficiency of this geothermal system, the high-pressure jet grouting (HPJG) technology is proposed to enhance thermal output in deep buried U-shaped well (DBUSW) system. By means of this technology, an artificial jet grouting column (JGC) with high thermal conductivity is built near the horizontal well segment. The emphasize of this work is to evaluate the feasibility and efficiency of the proposed heat production method. Numerical simulations were conducted via a field validated model from in-situ experiments in Xian. Results demonstrated that average annual heat production rate is improved by about 22% in the 30-year heating period, with building an artificial JGC with 1.0 m radius near the wellbore. These results indicate that the proposed method is a promising strategy for enhancing thermal output in the DBUSW. Sensitivity analyses suggest heat production rate and outlet temperature are mainly controlled by the radius of the JGC, while very high JGC thermal conductivity has less effect. Given the field conditions, the suggested thermal conductivity and radius of artificial JGC is 30 W/m °C and 2.0 m, respectively. [ABSTRACT FROM AUTHOR]

Ground Penetrating Radar (GPR) is widely utilized in detecting subsurface distress. However, its identification and analysis still face challenges. We propose a method based on the Generative Adversarial Network (GAN) to process GPR B-scan data containing semi-rigid base loose distress. An end-to-end GAN invert GPR B-scan into cross-sectional images of the road. A U-net is used in the generator to transform from GPR B-scan to road loose models. A patchGAN is used in the discriminator to determine the correlation between the GPR B-scan and road loose models. We used Finite-Difference Time-Domain (FDTD) and random mediums to construct the road loose distress model. Based on this model, the simulated dataset of 14,000 sets of images was randomly generated. Post-processing of the simulated dataset generated the synthetic dataset of 14,000 sets of images. The identification results trained on the simulated dataset and synthetic dataset achieved 90 % and 97 % average Structural Similarity Index (SSIM) compared to the source images. Through threshold segmentation of the generated images, 3D models are reconstructed using Marching Cubes (MC). Validation with the actual project indicates that this method effectively recognizes loose distress, and the generated 3D distribution model accurately represents the road condition. This approach offers a promising solution to the challenge of radar image identification and introduces a new data inversion method for road nondestructive testing. • Developing multi-layer random media models to generate the dielectric structure of the road and simulating GPR B-scan images of loose distress. • Constructing a GAN to identify the distribution and severity of loose distress in semi-rigid base roads, achieving an average SSIM of 97 %. • Utilizing the MC algorithm to reconstruct 3D models of the distress and road structure, accurately reflecting the actual size and distribution. [ABSTRACT FROM AUTHOR]

Although the Ku-band Cassini RADAR was not primarily designed to probe Titan's subsurface structure, it unexpectedly provided valuable data on penetration, notably measuring the depth and dielectric properties of several lakes or seas in altimetry mode. While the RADAR did not possess the same penetration capability as the radar instruments that are used to search for water on Mars, its detection results and potential still warrant comprehensive integration and summary. This paper reviews the latest research findings on Titan's subsurface observations, encompassing liquid bodies and dunes, grounded on RADAR's penetration performance and principles. In consideration of the Dragonfly mission and its scientific goals, the paper reviews the distribution of water ice on Titan. The upcoming observations hold promise for investigating relevant features at low latitudes, such as impact craters with exposed ice-rich material. Finally, suggestions and prospects for future subsurface radar exploration of Titan are presented. The exploration of subsurface structures on Titan remains a captivating field of study, bearing significant implications for planetary science and astrobiology. [ABSTRACT FROM AUTHOR]

This paper presents the coeval history of a sandy coastal barrier and four lagoon margins located in the Rio Grande do Sul State, southernmost Brazil. To achieve this objective we compared the Holocene relative sea-level changes recorded along a regressive coastal barrier with the register of base-level fluctuations preserved in the lagoon terraces. We used geomorphology, geochronology, geophysics (GPR), and high-resolution sequence stratigraphy to evaluate changes on the relative sea- and base-level recorded in the barrier and lagoon terraces, respectively. The record of the relative sea-level fall (forced regression) began at ∼4 ka in the coastal barrier and around 3.4 ka in the lagoon system. Maximum altitudes of the eolian/beach deposits boundary are similar on both barrier and lagoon settings, hence pointing out that relative sea-level controlled lagoon base-level. The forced regression stage is more accurately preserved in the margin of the lagoons than in the coastal barrier. Along the former, four progradational sets related to stepped terraces record pulses of relative sea-level fall at 3.4, 1.4, 0.35, and 0.27 ka. The pulses that took place from 1.4 ka onwards are recorded as low terraces in the lagoon but appear in the coastal barrier as an acceleration in the rate of the relative sea-level fall. Each relative sea-level fall is supposed to have liberated beach sands for eolian reworking during the subsequent stillstand phase and allowed the development of transgressive dunes. Therefore, we conclude that lagoonal terraces vertical displacements are adequate proxies for high-resolution analysis of relative sea-level changes. • Local deposits of marine coastal barrier and adjacent lagoon margin demonstrate synchronicity of deposition. • Lagoon deposits are adequate proxies for high-frequency of relative sea-level changes. • Four terraces record relative base-level falls and associated forced regression in local lagoons. • Forced regression is registered as four progradacional pulses starting at 3.4, 1.4, 0.35 and 0.27 ka. [ABSTRACT FROM AUTHOR]

This work analyzes the geological evolution of sedimentary deposits in the coastal aquifer of Garopaba, south Brazil, using ground penetrating radar (GPR) and data from tubular wells. The aquifer is localized in the coastal plain, where Quaternary lagoon-barrier environments are set between the Precambrian crystalline mountains and the sea. Over ten tubular wells are scattered in urbanized areas, which highlights the vulnerability of the unconfined, granular shallow aquifer. The results show that the aquifer has lithologic units of local scale. Tubular well data show the basal limit of the aquifer overlying clayey layers between 30 and 40 m deep and intercalation of sand layers up to the surface, mostly fine to very fine sand, with metric thickness, secondary lenses of clay and minor occurrence of gravel. The radarfacies interpretation shows fluvial-estuarine deposits as a local hydrostratigraphic unit, with lateral accretion bars filling a NE-axis paleochannel. The basal surface of the channel is interpreted as the sequence boundary surface of the lagoon-barrier systems III (upper Pleistocene) and IV (Holocene). The geological evolution of the aquifer is related to the upper Pleistocene marine regression (120–18 ka), that caused the aerial exposure of the continental shelf, and the development of complex drainage channels, which were superimposed during the Holocene transgression by lagoon-barrier IV deposits. After the post-glacial transgression, the lowering of the RSL to the current level promoted the silting of part of the lagoon system by continental sedimentation and aeolian deposits composing the surface. • The geological evolution of Garopaba coastal aquifer is analyzed, using ground penetrating radar (GPR) and tubular well data. • The aquifer has its genesis related to four evolutionary stages from the upper Pleistocene to the Holocene. • Lithofacies influence the groundwater behavior; paleochannel areas suggested for new wells to improve groundwater management. • Extreme vulnerability in unconfined sandy areas, high to medium vulnerability in sandy-clay or thinly covered clay areas. [ABSTRACT FROM AUTHOR]

Long-term hydroclimate variability recorded in lake sediments from Estonia provide information about environmental changes in northern Europe during the Holocene. Lake Pangodi is a semi-closed basin lake in southern Estonia with a large surface area to volume ratio, making it sensitive to effective moisture balance (precipitation minus evapotranspiration), which is recorded as changes in the lake level. Here we conducted a ground penetrating radar (GPR) survey, sedimentological analyses, radiometric dating and lake level modeling study to identify periods of lake-level high- and low-stands. The radiocarbon-dated sedimentary stratigraphic features on our radargram support the model results, suggesting that Lake Pangodi formed at ∼12.8 ka. The water levels were likely variable during the early Holocene, and the comparison of Lake Pangodi sediment facies and the lake level model show relatively stable lake water depth between ∼9.8 ka and ∼2.4 ka, and an increase towards modern. A notable reduction in lake levels occurred between ∼8.2 and ∼7.7 ka, likely due to a significantly reduced precipitation-evaporation balance. Our middle Holocene reconstruction suggests water column depths nearly 2.0 m lower than modern. This aligns with the results from studies conducted in the Baltic region, yet contrasts those from Scandinavia, suggesting different hydroclimate driving mechanisms during the Holocene variations in hydrogeological regimes. Our model detected the most abrupt rise of 1.7 m in water levels between ∼1.5 and ∼1.3 ka. This study highlights the need to develop proxies from single lake basins combining multiple methods for a better spatiotemporal resolution of paleo-hydrological changes. • Lake Pangodi sediment facies reveal centennial-scale fluctuations in water levels. • Reduced lake levels between 8.2 and 7.7 ka due to decreased precipitation. • Middle Holocene water levels in Lake Pangodi were nearly 2.0 m below modern. • Abrupt rise in water levels by 1.7 m detected between 1.5 and 1.3 ka. • Study highlights need for proxies and multiple methods for better paleo-hydrological resolution. [ABSTRACT FROM AUTHOR]

The use of analogues of previous river styles is highly significant for successful river restoration, yet some existing techniques available to assist practitioners are still not widely applied. We explore the use of Ground Penetrating Radar (GPR), to explore past river styles in an upland river valley in the UK, and explore the potential of the approach to reconstruct former channel pattern. Post-glacial evolution of upland floodplains has been influenced by temporal changes in vegetation, sediment supply and hydrological regime. Channel-floodplain morphodynamics over the Holocene were conditioned by glacial deposits, lateral interaction with slope processes and fluvial sediment reworking, changes in flow and sediment supply regimes driven by climatic change, and more recently direct and indirect anthropogenic activities, e.g. deforestation, floodplain land use and channel modification. Current drives towards river restoration often use floodplain topography as a guide to appraise such a planform state, however, reconstruction of former channel state is often restricted to surface features visible on historic maps and aerial photographs. This research focuses upon the floodplain of the upper Swindale Beck, Lake District, UK, which was recently restored to a planform design based on the recent meander pattern visible in floodplain topography. We show the potential of GPR to reconstruct a wider array of past channel pattern and evolution at a site characterised by largely aggradational conditions and consistent sediment supply from glacial deposits at the valley head. Analysis of GPR data from 40 intersecting GPR survey lines revealed several stratigraphic units, including gravel braidplains, berms, chutes and bars, several levels of larger channels and their layered fill as well as backwater deposits. These were interpreted as braided systems, dynamic wandering planform and single-thread meandering systems with spatial transitions conditioned by tributaries and valley slope. Optically Stimulated Luminescence (OSL) dates in combination with GIS analysis of valley slope, channel gradient and local valley floor aspect allowed the interpretation of individual evolutionary stages of river and floodplain development at Swindale over at least the last millennium and provides links to processes in the wider environment including the role of alluvial fans in supplying sediment and forcing channel migration. Such information can be particularly valuable for restoration projects to aid design of channel dimensions, planform configuration, channel gradient, substrate characteristics and connection with tributaries. While restoration generally aims to resemble a more natural reference state, specific targets may seek to improve a particular set of functionalities (e.g., ecological, flood and sediment management, recreational) which should be resilient to the consequences of ongoing climatic changes and should be achieved sustainably (e.g. locally sourced gravel). Here, GPR-based floodplain analysis provides a non-invasive approach to understand possible evolutionary trajectories and to appraise a wider range of restoration options and sustainable resources. • Ground Penetrating Radar (GPR) reveals floodplain evolution over last 1000 years • Transition from braiding to wandering river style preserved in aggrading setting • Sediment supply from moraines and lateral fan activity influence planform change • River restoration design can benefit from undertaking GPR subsurface analysis [ABSTRACT FROM AUTHOR]

Glacial Lake Agassiz strandlines expressed in LiDAR-based digital elevation models are detailed records of past water level change that reflect outlet incision and switching. Detailed 1:24,000 scale surficial geology mapping of a small section of coastline east of Crookston, MN, reveals strandlines of the Lockhart, Emerson, and Nipigon phases. Other than the Campbell and youngest Tintah Beach, the strandlines are not identified using the naming convention established near the southern outlet (Herman, Norcross, Upham, Tintah) because of the increasing number of strandlines northwards. The strandlines, for the most part, naturally exist in elevation clusters, and are assigned to 11 strandline groups (SG). SGs 1–9 are of Lockhart age at elevations higher than the Tintah Campbell Gap (TCGap). Elevation gaps between SGs are ~1–3 m, greater than the 0.5–2 m gap between successive strandlines within a SG. The many (n = 70) small, low-relief strandlines are interpreted to record nearly continuous incision of the southern outlet sill during Lockhart Phase. Beach ridges are estimated to have formed every ~20 years. The TCGap is ~4 km wide in the study area. The Campbell Beach of Emerson Phase age consists of several embayments, beach ridges and the large Melvin Spit. Based on morphological comparison with the modern Gull Point Spit in the Lake Erie basin, the Melvin Spit took ~500 years to form, during which water level dropped 8 m. The Nipigon Phase strandlines are small discontinuous beach ridges. North-south elevation plots of the most continuous strandline in each SG records southward slopes of 1.1 to 0.19 m/km explained by differential glacioisostatic adjustment active during strandline development that decreases through time at lower elevations. The three highest elevation OSL dates agree with published ages for the older strandlines (~14.4 ± 1.5 ka), but younger dated Tintah, Campbell, and sub-Campbell beaches are 2–5 ka older than published ages. Ground penetrating radar (GPR) datasets acquired at 11 sites at frequencies between 100 and 500 MHz, representing a cumulative distance of 11 km, form the basis for a simple beach ridge formation model augmented with hand auger holes and shallow hand-dug pits. Six radar facies (RF) were identified, dominated by RF2 which consists of lakeward-dipping reflections with a downlapping lower boundary recording a depositional regressive system, and RF4 which consists of landward-dipping reflections with a downlapping lower boundary recording overwash deposits from proposed storm events. Spit orientations and GPR data indicate littoral drift was southwards with offshore bars possibly nucleating successive beach ridges upon ~1-m drops in water level. Detailed analysis of strandlines from paleo lakes offer promise for high resolution reconstructions of past water level history. • Strandlines, primarily beach ridges, cluster with ~1 m elevation spacing. • Strandline clusters are strandline groups with ~1–3 m elevation spacing. • Southern outlet sill incision was 1–3 m every ~20 years during Lockhart Phase. • Beach ridge model with 5 ground penetrating radar facies based on 11 km of GPR data. • OSL dating of strandlines gives mixed results for Tintah and younger beaches. [ABSTRACT FROM AUTHOR]

Global warming and human activities are accelerating the degradation of permafrost on the Qinghai-Tibet Plateau (QTP), leading to significant settlement and cracking issues in the local express highway infrastructures. In response, the Gonghe-Yushu Express Highway (GYE) on the east edge of the QTP incorporated extensive cooling measures during its construction to enhance embankment stability. Despite these efforts, field investigations have disclosed that embankment diseases persist across various sections, including those with implemented cooling measures. This study focuses on a specific test and demonstration section of the GYE, employing a suite of cooling measures to assess their engineering effectiveness. Utilizing a combination of multi-time ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) detection, alongside on-site disease investigations and temperature monitoring, this research comprehensively evaluates the efficacy of different cooling interventions. Findings indicate that although cooling measures generally curb permafrost degradation in areas with ice-rich and ice-saturated soils, they fall short in sections with massive ground ice. Of the six cooling measures examined in the demonstration section, ventilation duct embankments emerge as the most effective, whereas crushed-rock layer embankments rank as the least. The study further reveals that the combined use of XPS insulation boards and two-phase closed thermosyphons inadequately addresses the issue of central heat accumulation in broad-width express highways, reducing uneven settlement issues but aggravating longitudinal cracking. Comparative analysis of on-site surveys and monitoring data suggests that regular application of GPR and ERT techniques can proficiently assess the performance of cooling measures. • GPR and ERT effectively evaluate cooling measure performance. • VD embankment most effective，CRL embankment least. • XPS-TPCTs embankment fail to address central heat accumulation. • Composite cooling measures superior to singular measures. [ABSTRACT FROM AUTHOR]

The increasing length of subsurface pipe causes overlapping, accumulation, and occasionally the old pipe layout is not also available. Consequently, accidents, damages, time delays, and financial losses occur during construction of new structures or installation of new pipes. Therefore, depth, radius, material of the existing pipe, and map of pipe are indispensable for knowing proper construction planning. In this article, an algorithm is proposed to estimate the properties of subsurface pipes and show 3D maps. Using this algorithm, the radius of the field pipes was estimated with 83, 67, and 89 % accuracy and depth with 95, 95, and 98 % accuracy. The effect of pipe radius should be considered to assess the pipe depth with higher accuracy. The material of the field pipe was successfully determined using the evaluated relative permittivity. A 3D map of the field pipe was developed by applying the tracing algorithm and linear regression on estimated depth. [ABSTRACT FROM AUTHOR]

In ground penetrating radar (GPR) images, the signals from reinforcing steel bars (rebars) can significantly obscure the signals of void defects beneath them, which hinders defect detection in tunnel linings. This study introduces a novel, end-to-end unsupervised deep learning-based network that is trained on unpaired GPR images. The primary objective is to suppress the rebar signal and enhance the accuracy of void defect identification in recorded GPR B-Scan images. The network incorporates an autoencoder generator with feature attention and feature mix-up modules, designed to recover textural information and generate improved images devoid of rebar interference. Crucially, this network leverages a strategy of comparing images in feature space, rather than pixel space. The features extracted by the autoencoder are constrained by cycle perceptual consistency loss, derived from a pretrained VGG19 network, to ensure fidelity and perceptual accuracy. Furthermore, this study introduces an enhanced Faster-RCNN network, specifically improved through a more robust feature extraction module, for detecting void defects beneath rebars. The effectiveness of the proposed method has been thoroughly validated using both synthetic and real-world data sets. The results indicate that our method not only surpasses other unsupervised techniques in performance but also effectively diminishes rebar signals and accurately reconstructs and identify void defect signals. [ABSTRACT FROM AUTHOR]

[Display omitted] • High-resolution imaging of underground structures was conducted by GPR and ERT technologies. • A three-dimensional contamination plume model of heavy metal(loid)s in a soil-groundwater system was established. • The influence of SWC and Ks on the migration potential of heavy metals was revealed. • The influence of hydrogeological conditions and soil characteristics on heavy metal(loid) distribution was revealed. The heavy metal contamination at abandoned smelting sites is receiving increasing attention. This study focuses on an abandoned lead–zinc smelting site and uses several methods (such as soil sampling, geophysical exploration, and groundwater monitoring) to systematically investigate the contamination characteristics, distribution patterns, and migration mechanisms of heavy metal(loid) in soil and groundwater. A geological structure model of the study area was established through drilling data and geophysical techniques (Ground penetrating radar (GPR) and Electrical resistivity tomography (ERT)), revealing the relationships among soil resistivity, electromagnetic wave reflection characteristics, and geological structure. This study revealed that heavy metal contamination in soil was concentrated mainly northwest of the site and was closely related to historical smelting activities. The presence of heavy metal(loid)s in groundwater had a complex correlation with soil physicochemical properties and environmental elements, and its distribution was influenced by both hydrogeological conditions and soil properties. This study also investigated the effects of the soil water content (SWC) and soil hydraulic conductivity (Ks) on heavy metal(loid)s migration and reported that high SWC and Ks contribute to the dissolution and migration of heavy metals. In addition, a 3D visualization model of heavy metal contamination plumes was established via Voxler software. This model intuitively demonstrated the migration and diffusion of heavy metal(loid)s in the underground environment, offering a novel perspective on their subsurface behavior. The research results provide important information for understanding the migration of heavy metal(loid)s in soil-groundwater systems. [ABSTRACT FROM AUTHOR]

While ground penetrating radars have been extensively researched on Earth, the high-resolution exploration and imaging of the shallow subsurface of celestial bodies in our solar system is still in its early stages, with only a handful of systems capable of the task. Designing high-resolution radar systems can be a complex task due to the large frequency bandwidth required by the antennas to achieve high vertical resolution. The WISDOM GPR, as part of the 2028 ExoMars mission, is a highly capable and challenging instrument in this context, given its fully-polarimetric setup and mission constraints on the operating environment, robustness, as well as mass and size budget. This paper outlines the development and characterization process of the WISDOM antenna assembly, which can serve as a model for future radar systems. Furthermore, it presents the results of the antenna characterization as the foundation for instrument calibration and optimal radar sounding outcomes. • WISDOM will reveal the shallow subsurface of Oxia Planum. • Lightweight, ultra wideband antenna system supports the radar performance. • Stiff and rugged antenna design withstands the Mars environment. [ABSTRACT FROM AUTHOR]

Instrumental sea-level records are insufficient to understand the response of sea-level changes to global temperature on centennial timescales. Sea-level histories spanning at least the Common Era have not been widely studied in Southeast Asia. This period is crucial for providing a pre-industrial context to understand sea-level change with climate. Linking sea-level change to climate change is proxy dependant, with most proxies only providing decadal to centennial scale resolution of both sea level and climate. This study examines the efficiency of beach ridge stratigraphy as a proxy for reconstructing regional sea-level histories in the tropics. We present topographically corrected Ground Penetrating Radar (GPR) profiles from a prograded coast in Phra Thong Island, Thailand, where we identify downlap point marking the boundary between the foreshore and shoreface subzones and use this as a past low-tide marker. The low-tide markers were corrected (considering the tidal range) and then connected to approximate the past sea level. Optically Stimulated Luminescence (OSL) samples collected at locations slightly offset from the shore-normal GPR profile line were incorporated to create a relative sea-level record. Overall, the shore-normal GPR record shows a ∼ 1.06 m fall in sea level between ∼2660 and ∼ 370 years ago. The study also highlighted stepwise fluctuations in sea level that were not identified in previous studies. Between ∼2600 and ∼ 2200 years ago, the record indicates a steep fall in sea level, followed by a phase of relatively stable to slightly falling sea level between ∼2200 and ∼ 550 years ago. Finally, for the seaward side, between ∼550 and ∼ 350 years ago, the record indicates an accelerating sea-level fall. This study confirms that the investigation of tropical beach ridge systems using GPR and OSL techniques can be a highly efficient and effective means for reconstructing regional sea-level trends throughout the Common Era and beyond. • Beach ridge systems preserve paleoenvironmental records. • GPR is a useful tool for probing geological records preserved in a prograded beach. • Tropical beach ridges studied with GPR and OSL effectively unveil sea-level trends. • Phra Thong Island experienced a stepwise sea-level fall during the late Holocene. [ABSTRACT FROM AUTHOR]

This study presents the monitoring of the contamination and remediation processes of an aquifer system using the ground-penetrating radar (GPR) method. To achieve this, periodic GPR measurements were performed on a flow cell, which was established to simulate aquifer contamination and remediation scenarios. The exterior of the flow cell was made of plexiglas, and a small hole was created at the top center to inject Dense Non-aqueous Phase Liquid (DNAPL) contamination. To study contaminant distribution and remediation processes, DNAPL Trichloroethylene (TCE) was used as the groundwater contaminant. Methyl-beta-cyclodextrin (MCD) was used as remediation agent. The interior of the flow cell was packed with two different sand grain size distributions: low permeability sand along the bottom and a higher permeability sand along the top. Common offset GPR measurements were performed along the top plane of the flow cell. The GPR measurements were conducted periodically over a total duration of 66 days, encompassing the phases prior to injecting DNAPL TCE, after injection of DNAPL TCE, and during the remediation process using MCD. Time-lapse GPR data were analyzed using 1D and 2D plots. In addition, to evaluate and monitor the contamination and remediation processes within the flow cell, central traces of the time-lapse GPR dataset were inverted by full-waveform inversion to estimate the dielectric properties of the layers and the depth by Particle Swarm Optimization (PSO). To utilize PSO, a forward model calculation using 1D finite difference in time domain adapted to PSO algorithm to generate theoretical GPR traces to compare the theoretical model GPR traces to the measured GPR traces as a "goodness of fit" metric. The electrical conductivity, relative dielectric permittivity, relative magnetic permeability, and depth of the layer were estimated by PSO of the GPR data. The results of the inversion process indicated a significant change in the estimated electrical conductivity values for the post TCE DNAPL contamination stage and the remediation stage. In addition, to support the inversion results, contaminant mass removal was quantified using moment analysis from dissolved-phase contaminant concentrations collected from the flow cell over time. According to the mass recovery calculation by moment analysis, which was collected via an outlet from the flow cell, approximately 38 % of the injected DNAPL TCE mass was removed by enhanced dissolution from the representative aquifer domain of the flow cell during the remediation stage of the experiment. • Time-lapse GPR measurements on DNAPL TCE injected flow cell model. • Full-waveform inversion by PSO application on surface GPR data. • PSO estimates dielectric properties of the flow cell indicating TCE presence. • Estimated electrical conductivity values increases during remediation. • PSO inversion of GPR provides monitoring contamination and remediation process. [ABSTRACT FROM AUTHOR]

Controlled forensic geophysical research involving GPR has proven to be a valuable resource, and the information gathered from these studies has been applied to forensic casework. The probability of detecting a grave for a longer postmortem interval differs with the soil type and the materials added to the grave with the body. In the studied case a detailed GPR survey was conducted in the Basilica della Trinità at Venosa a village located about 40 km north from Potenza (Basilicata, Italy). Unfortunately during the restoration works of the Basilica, there was a cement spill inside a sarcophagus containing human remains. The necessity to perform the genetic analysis of medieval human remains to reconstruct the distribution of the original line of descent of the Norman noble families aimed the need to understand whether or not there was a body inside the sarcophagus and, if so, its exact position. The radar profiles from this survey showed the clear amplitude contrast anomalies, emanated from the corpses. The strongest amplitude contrasts are observed at around 0.2–0.5 m depth which is consistent with the depth of the buried corp. • Ground Penetrating Radar. • Sarcophagus. • buried bones. • 3D analysis. • Excavated bones. [ABSTRACT FROM AUTHOR]

Ground-Penetrating Radar (GPR) has been widely used for non-destructive testing of earth dam disease. However, the forward simulation of GPR for earth dam disease often employs layered homogeneous models, neglecting the influence of medium randomness on its wave field characteristics. Therefore, considering the randomness of the medium, a geoelectrical model for earth dam disease is established, which is based on the mixed-type autocorrelation function and the finite element time-domain method. The influence of random medium model parameters on the single-channel wave of GPR is analyzed. The electromagnetic wave propagation characteristics under different medium models are explored. The forward simulation of GPR for earth dam disease such as panel voiding, concentrated seepage, and loosening are performed. The differences in propagation characteristics for earth dam disease between uniform medium model and random medium model are compared. Compared to the calculation results of the uniform medium model, the propagation speed and amplitude of electromagnetic waves in the random medium model changes, and a number of diffraction waves are present. When performing forward simulation of GPR for earth dam disease, considering medium randomness can deepen the understanding of the GPR section view and help improve the accuracy of image interpretation. • Constructing the random medium model with the mixed-type autocorrelation function. • Adopting the finite element time-domain method for the numerical simulation. • Considering medium randomness can improve the accuracy of GPR image interpretation. • Random medium model parameters have an effect on GPR single-channel waves. • Applying the random medium model for earth dam disease GPR simulation is valuable. [ABSTRACT FROM AUTHOR]

Different palaeoenvironmental features that pose natural geological, environmental, and engineering hazards to human operations occur frequently around the Nile Valley. Moreover, where these features were initially created, their relevance focuses on how the urban communities responded to the processes. So, a ground penetrating radar (GPR) field survey was carried out on different paleoenvironments of Pre-Quaternary and Quaternary sediment around Assiut. Deep and critical analyses of georadar facies were made to obtain clear images of these features with unprecedented resolution. The main objective of this study is to find some reasonable geological interpretations for these features. From this study, it is possible to identify and differentiate these features originating from different geological environments and climatological conditions in arid regions such as those around Assiut. In addition, the study serves as guidelines for environmental management and climatic changes for enhancing knowledge of urban development. Also, the study demonstrates how georadar can be used to create precise images of intricate shallow subsurface anatomy with possible palaeoenvironmental and palaeoclimatic indicators. • Create precise images of different subsurface features by GPR reflections. • Differentiate some features originating from different geological environments. • Trace of buried structures that may cause further damage in arid regions. • Significance of GPR imaging for minimizing potential risks facing future developments. [ABSTRACT FROM AUTHOR]

Canossa Castle is located in the municipality of Canossa 18 km South of Reggio Emilia (North Italy). It was constructed in 940 by Adalberto Atto, son of Sigifredo of Lucca. Lombard chieftains needed this strategic hill to defend their lands against intrusions of other barbarian tribes. Subsequent improvements made the stronghold one of the best-defended castles in the country. Canossa Castle became particularly famous as a site of reconciliation between King Henry IV and Roman Pope Gregory VII during the Investiture Controversy in 1077. To redevelop the area and create an easy tourist route, the Superintendence of Archaeology, Fine Arts and Landscape for the Metropolitan City of Bologna and the Provinces of Modena, Reggio Emilia and Ferrara planned excavations in the area close to the Castle. To get precise information on where to carry out excavations geophysical surveys were undertaken in the spring of 2021. The castle stands on a rock with a steep slope and dense vegetation and this makes it very difficult to carry out geophysical prospecting. This guided the choice of geophysical methodologies to be used. For this reason, electrical resistivity tomography was used along the steep slope, while in the narrow flatter area, the ground penetrating radar methodology was used. The results demonstrate the effectiveness of the chosen geophysical methodologies. • the Castle of Canossa. • geophysics on a rock with a steep slope and dense vegetation. • 3D resistivity anomaly probability tomography method. [ABSTRACT FROM AUTHOR]

Fracture stratigraphy study for a subsurface sedimentary rock sequence can be a challenging and demanding task. Typically, the data obtained from seismic and well-logs are heavily impacted by resolution issues and are difficult to interconnect. In this work, we document and extract fracture properties (orientation, density, intensity, etc.) from a layered carbonate sequence for fracture stratigraphy characterization. High-resolution subsurface Ground Penetrating Radar (GPR) data images, coupled with drone and previously documented well-log profiles, were analyzed to achieve the structural characterization task. The studied outcrop is localized in the Potiguar Basin (Brazil), where the Cretaceous Jandaíra Formation carbonates are exposed for hundreds of meters. The sequence is subdivided into an upper packstone/grainstone portion and a lower wackestone bed package. We documented the higher fracture intensity/density in the lower bed package portion, highlighting that depositional texture and intra-bed stylolites control the higher fracture distribution in the sequence. Finally, a 3D conceptual model describing the overall results is presented. This model summarizes and shows the innovative fracture stratigraphy method based on the GPR data analysis. • GPR data could be used as digital subsurface outcrop for structural data acquisition and characterization. • Sedimentary facies, bed interfaces, and bed-parallel stylolites control the structural elements distribution. • Wackestone facies are more fractured with respect to packestone/grainstone facies due to intra-layer stylolites. • The fracture distribution varies along the studied bed packages association. [ABSTRACT FROM AUTHOR]

• Field-scale assessment of SOC is essential for sustainable and site-specific agronomic management. • Efficient and rigorous methods are needed to reduce sampling efforts without losing critical information. • Spatial simulated annealing was used to reduce the sampling scheme while minimizing information loss. • The role of the variogram model choice and of the use of covariate information was evaluated. • Results demonstrated that it was possible to reduce the original sampling scheme without compromising predictive capability. Assessing soil organic carbon (SOC) at the field scale is crucial for efficient environmental and agronomic management, especially within the precision agriculture framework. This enables the implementation of crop and soil management strategies to enhance soil quality, increase carbon sequestration, and improve crop yields. However, the process of sampling and assessing SOC is resource-intensive, demanding both in time and labour. This aspect is particularly relevant in agronomic research, where the need to assess the spatial correlation structure of the investigated variables requires the collection of large datasets with georeferenced data and often measurements need to be repeated over time as in the case long-term field experiments − LTE. Methods for minimizing information loss while reducing the sampling scheme, such as spatial simulated annealing (SSA), are particularly valuable in the scope of SOC assessment, especially when faced with budget and time/labour constraints. Within the structure of the SSA method, two critical components can be identified: i) the inclusion of highly informative covariates for the primary variable (SOC); ii) the selection of the most appropriate variogram model for spatial variability assessment. Covariates strongly correlated with SOC, such as those obtained from ground penetrating radar (GPR) that can be collected at a higher spatial density compared to SOC data, along with a well-performing model, can significantly enhance the efficiency of the sampling scheme reduction process. We conducted a study using data from an agronomic field experiment, which included 71 georeferenced sampling locations and, through an iterative downsizing process utilizing SSA, we progressively reduced the number of sampling points by removing 10, 15, and 20 observations. The sampling scheme was refined according to two distinct variogram models: the spherical and Gaussian-Matérn models, both for the primary variable (SOC) and the covariate GPR variable. This process allowed us to identify the optimal variogram model, which has a key role in maximizing the reduction of redundant points while preserving those with valuable information, and to assess the role of the covariate variable both in improving the optimization of the sampling scheme for SOC and in replacing the primary variable to optimize the sampling scheme. Finally, to assess the impact of sampling scheme reduction, a validation process was performed by estimating the dropped points by means of the remaining points using ordinary kriging and regression kriging and analysing the accuracy of such estimation. Our analysis demonstrated that it was possible to reduce the original sampling scheme by approximately 20%, equivalent to eliminating 15 sampling points out of 71, without compromising its predictive capability. [ABSTRACT FROM AUTHOR]

The aging and complexity of underground water pipes pose significant challenges to modern society, necessitating long-term monitoring and maintenance to prevent the socioeconomic costs. So, effective nondestructive and geophysical methods are needed to localize the possible leakage areas before any rational opening up is conducted. In this study, we propose a workflow to generate instantaneous frequency slices (IFS) from raw ground penetrating radar (GPR) data. Characterizing the horizontal and vertical patterns of water leakage using IFS revealed two key mechanisms—reflections due to the dry and wet interface and absorption due to water distributed in soil—that significantly influence instantaneous frequency. A well-designed real site (Q-Leak), in collaboration with the Water Supplies Department (WSD) of the government, was conducted to replicate typical leakage scenarios, validating the effectiveness of our IFS-based approach. The results of proposed method demonstrate that IFS is a reliable approach for characterizing leakages in buried water pipes, effectively addressing several challenges associated with amplitude slice analysis. Our proposed methodology enriches the toolkit available for large-scale, future-oriented water leakage detection. [ABSTRACT FROM AUTHOR]

Accurate estimation of sub-surface properties such as moisture content and depth of soil and vegetation layers is crucial for applications spanning sub-surface condition monitoring, precision agriculture, and effective wildfire risk assessment. Soil in nature is often covered by overlaying vegetation and surface organic material, making its characterization challenging. In addition, the estimation of the properties of the overlaying layer is crucial for applications like wildfire risk assessment. This study thus proposes a Bayesian model-updating-based approach for ground penetrating radar (GPR) waveform inversion to predict moisture contents and depths of soil and overlaying material layer. Due to its high correlation with moisture contents, the dielectric permittivity of both layers were predicted with the proposed method, along with other parameters, including depth and electrical conductivity of layers. The proposed Bayesian model updating approach yields probabilistic estimates of these parameters that can provide information about the confidence and uncertainty related to the estimates. The methodology was evaluated for a diverse range of experimental data collected through laboratory and field investigations. Laboratory investigations included variations in soil moisture values, depth of the overlaying surface layer, and coarseness of surface material. The field investigation included measurement of field soil moisture for sixteen days. The results demonstrated predictions consistent with time-domain reflectometry (TDR) measurements and conventional gravimetric tests. The correlation coefficient between predicted soil permittivity and that measured by TDR ranged from 0.84 to 0.99 for the presence of up to 10 cm of overlaying surface layer. The depth of the surface layer could also be accurately predicted for up to 10 cm, while at higher depths, prediction outliers could be reasonably identified from the obtained probability distributions and uncertainty. Hence, the proposed method provides a promising approach for uncertainty-aware sub-surface parameter estimation that can enable decision-making for risk assessment across a wide range of applications. • Probabilistic prediction of sub-surface parameters using GPR waveform inversion. • Simultaneous estimation of permittivity, conductivity, soil moisture, and depth. • Soil moisture can be predicted in the presence of an overlaying organic layer. • Overlaying organic layer can be characterized for wildfire risk assessment. • Probabilistic uncertainty can be leveraged to identify inconsistent predictions. [ABSTRACT FROM AUTHOR]

This article presents a methodology that can be used to identify and estimate the positions of features within the hidden bearing region of Reinforced Autoclaved Aerated Concrete (RAAC) roofing planks. The method requires the careful design of a dielectric filled wedge to hold a Ground Penetrating Radar (GPR) sensor at a fixed angle relative to the surface of RAAC planks to enable novel angled beam examination of the end bearing. Interpretation can be performed using time-of-flight and Fermat's principle. The approach was experimentally trialed on in-situ RAAC ceiling planks within an active hospital estate with the results validated by conventional intrusive surveying techniques, demonstrating agreement with the GPR results. • Angled beam GPR could be used as a novel RAAC roof plank end bearing surveying method. • Using Fermat's principle, reinforcement position and bearing length are estimated. • Optimisation of GPR wedge design was achieved via finite element modelling. • Angled beam GPR results were validated by intrusive surveys from in-situ RAAC planks. [ABSTRACT FROM AUTHOR]

Tunnel lining defects, such as discontinuous reinforcing steel, concrete dehollowing, and incomplete pouring, can substantially undermine structural durability and stability. Addressing limitations such as strong subjectivity and low accuracy in traditional quality assessment methods, we introduce the YOLO-LD tunnel lining quality detection algorithm. This model is an adaptation of the original YOLOv7 algorithm, where the original feature pyramid network is substituted by an asymptotic feature pyramid network, and a convolutional block attention module is added subsequently to backbone extraction. Electromagnetic wave propagation is simulated using gprMax3.0, while the tunnel lining structure is imaged through ground-penetrating radar employing the finite-difference time-domain method. These simulations yield a comprehensive radar image dataset for tunnel lining quality evaluation. A performance comparison of YOLO-LD with four other established algorithms reveals its superiority in detecting the three aforementioned defects, yielding an mF1 score of 91.07 % and a mAP score of 94.13 %. The model demonstrates robust performance in comprehensive defect detection and generalization. • Employing the Finite Difference Time Domain method to simulate the radar detection process. • A tunnel lining quality detection algorithm based YOLO-LD is proposed for tunnel lining radar images. • The use of asymptotic feature pyramid network avoids information loss in the feature fusion process. • The fusion CBAM attention module strengthens the feature extraction capability in space and channel. [ABSTRACT FROM AUTHOR]

The southern coast of Argentina is known for its high tidal ranges and large coarse-grained coastal barriers that have emerged over time as a result of the regional uplift. Well-preserved barriers can provide critical information about the morphological evolution of the coastal areas, and the relative evolution of the mean sea level, as long as their morphodynamics are well understood. In order to better understand the influence of tides in wave-built sedimentary bodies, an in-depth analysis of the architecture of a barrier system has been realized at the mouth of the Santa Cruz - Chico river estuary (50°S). Maximum tidal range in this estuary is 12 m. A great variety of morphologies compose both sides of the estuary inlet, from simple ridges and barrier spits to beach ridge plains. Barrier spits and beach ridge plains characterize the southern side, whereas elongated simple ridges and barrier spits isolating large tidal flats are more developed on the northern side. The site was investigated using ground-penetrating radar combined with digital elevation model analysis, and some sedimentological observations. Cross-shore profiles, with a penetration depth up to 5 m, show a large range of radar facies attributed to erosional surfaces, beach face progradation, and washover deposits. The slope of the beach face appears to be an effective parameter for differentiating between beach ridges plains and barrier spits, as the latter are characterized by steeper values. The combined analysis of the radar architecture and barrier morphology allows to identify five barrier sets, which have been associated with five different development stages along the late Quaternary: 1) Last Interglacial Maximum (MIS 5e), 2) Last Interglacial (MIS 5e/5c/5a), 3) Mid Holocene transgressive maximum, 4) Mid Holocene highstand reworking, and 5) Holocene regressive stage. Although the morphological model is in line with the observations made by other authors, it would be appropriate to consolidate the model by establishing an absolute chronology. • Wave-built sedimentary bodies in a strongly tide-influenced environment. • Beach face slope as a proxy for differentiating barrier spits and beach ridges. • StepPed berms as an indicator of high tidal ranges environments. • Transition from transgressive to regressive barrier during the Holocene. • Morphological evolution proposal with 5 main stages in a highly dynamic coastal area. [ABSTRACT FROM AUTHOR]

This study explores the morphological features and internal structure of small-scale washovers along the south-eastern Baltic Sea coast, providing insights into these most widespread yet often neglected deposits in the recent research of geomorphological and sedimentary record of storm surges. A 15-year-long record of morphological changes of the coast was acquired from regional orthophotos to analyse their geometry and spatial characteristics. Sedimentological analyses comprising a description of deposits, grain size and shape analyses, and Ground Penetrating Radar profiling were undertaken to investigate the internal structure of washovers. The formation of washovers appeared to be correlated with the average winter NAO (North Atlantic Oscillation) index. The study revealed different scaling relationships of selected spatial parameters in two coastal settings and extended previously hypothesized relationships of length-area, area-volume, and length-volume. The internal structure of washovers is defined by low-angle planar cross-stratification and horizontal stratification, both disrupted by small troughs. Grain-size data indicated extremely short transport of dune and beach sediments, lately deposited in the form of washovers. The study proves that in all domains, the geomorphological characteristics of washovers are scalable, despite the different coastal settings, and even small-scale washovers fit the existing development models. • Small-scale washovers fit and extend the existing geomorphological models. • Washovers tend to form and grow periodically on multiyear scale. • Georadar facies allow for identification of washovers in the sedimentary record. • Characteristics of washover deposits indicate local, short transport. [ABSTRACT FROM AUTHOR]

• Non-destructive approach to predict soil bulk density over larger areas. • Soil compaction influences geophysical responses. • Random forest approach identified important variables to predict bulk density. • Developed models show high accuracy in predicting bulk density. • These data Electromagnetic Induction and Ground-penetrating radar data can predict bulk density. Tillage and soil compaction affect soil properties, processes, and state variables influencing soil health, hydrodynamics, and crop growth. Assessing soil compaction levels using traditional methods, such as soil sampling and penetration resistance, is inefficient for scaling up from plot to field scales. Geophysical methods like Ground-penetrating Radar (GPR) and Electromagnetic Induction (EMI) are becoming prominent for assessing soil properties and state variables in agriculture due to their ability to overcome the limitations of traditional methods. However, a research gap exists in non-destructively estimating bulk density changes related to tillage and soil compaction. This study aimed to (1) assess the influence of soil compaction on GPR and EMI responses in boreal podzolic soil and (2) develop and evaluate prediction models to determine soil bulk density using GPR and EMI. The experiment was conducted by compacting loamy sand-textured soil using a lawn roller. GPR data were collected to determine the soil dielectric constant (K r) and the direct ground wave amplitude (A DGW), along with EMI-measured apparent electrical conductivity (EC a) under three compaction levels (no, four and ten roller passes). Relationships between K r , A DGW and EC a and the average bulk density of 0–0.30 m depth at three compaction levels were tested. A Random Forest (RF) regression approach was employed to identify the most significant variables for predicting bulk density. Simple and multiple linear regression (SLR and MLR, respectively) models were developed using EC a and K r and were subsequently evaluated. Results revealed significant differences between the measured bulk density and geophysical data across the tested compaction levels. During the model development, SLR and MLR showed R 2 > 0.65, and the model evaluation showed a root mean square error of < 0.14 g/cm3. This study highlights the potential of using GPR and EMI for the non-destructive prediction of bulk density in the agricultural landscape. However, further research is needed to explore the applicability and limitations of this approach across varying water contents, electrical conductivities, and soil types. [ABSTRACT FROM AUTHOR]

Road underground defect detection plays a crucial role in assessing transportation infrastructure. Ground penetrating radar (GPR) serves as a widely used geophysical tool for this purpose. However, the traditional manual interpretation of GPR images heavily relies on the experience of the practitioner, leading to inefficiency and inaccuracies. To tackle these challenges, this paper proposes an automatic detection method for underground defects of roads based on an improved YOLOv5s model. First, the dense connection structure is integrated in the C3 module of the backbone to form the Dense-C3 module to enhance the capability of feature extraction. Subsequently, a convolutional block attention module (CBAM) is incorporated after each Dense-C3 module to refine features and enhance efficiency. Furthermore, the focal loss function is employed for the confidence loss to mitigate the impact of sample imbalance on detection performance. Experimental results demonstrate that the proposed model achieves a mean average precision (mAP) of 96.4% for synthetic data and 91.9% for real data, outperforming seven other models. The detection speed of the proposed model for real data reaches 51 frames per second, meeting the real-time detection requirements of road underground defects. • The Dense-C3 module is constructed to improve the feature extraction ability. • The CBAM is added after each Dense-C3 module to refine features. • The focal loss function is used to mitigate the impact of sample imbalance. [ABSTRACT FROM AUTHOR]

• A deep learning method is proposed to identify multi-type objects in GPR images. • A comprehensive dataset is proposed to solve data scarcity. • Improved feature extraction module is designed. • A novel loss function is designed to solve sample imbalance. This study proposes an enhanced detection method for tunnel lining hidden objects based on the comprehensive Ground Penetrating Radar (GPR) dataset and an improved deep learning (DL) algorithm. To mitigate the issue of data scarcity, a tailored dataset consisting of six types of hidden objects was compiled, which contained 7426 on-site collected GPR images and 71,014 well-labeled objects. This bespoke dataset offered substantial support for algorithm training and validation, making it one of the most extensive datasets in the domain for tunnel lining GPR detection. An enhanced Faster R-CNN algorithm was then developed to effectively detect different types of hidden objects. Modifications were made in four key areas: Feature extraction module, Feature Pyramid Network (FPN), customized anchor scheme and modified loss function. This algorithm was subsequently trained and validated using the comprehensive dataset. Evaluation metrics demonstrated the performance of this approach, with a mean average Precision (mAP) of 81.2%. Results also proved particularly effective in detecting rebars, pipelines, and steel arches while demonstrating a shortfall in detecting voids and cavities due to the data limitation. The results underscore the potential of this enhanced algorithm for the automatic detection of diverse hidden objects in tunnel linings, thus stimulating further research in this vital field. [ABSTRACT FROM AUTHOR]

Reinforcement corrosion is a leading cause of damage in concrete bridge decks, resulting in cracking and spalling in the concrete cover. Recently, ground penetrating radar (GPR) emerged as a prominent non-destructive testing (NDT) for evaluating the corrosiveness of concrete structures. Although GPR provides real-time testing for concrete elements, the analysis and interpretation of GPR data can be complex and time-consuming. To this end, this paper introduces a comprehensive methodology for a fully automated GPR data interpretation in the context of reinforcement corrosion evaluation. The developed method encompasses robust rebar picking and corrosion mapping. The rebar picking is realized by employing advanced waveform analysis and a three-step automated thresholding approach. Following rebar picking and data extraction, corrosion mapping is performed, stepping on a statistically optimized amplitude thresholding process. The developed rebar picking module achieved more than 98% precision and recall. Furthermore, the standardized corrosion assessment methodology precisely pinpointed potential corroded areas. [Display omitted] • Waveform analysis and three-step thresholding realized automated rebar recognition. • Corrosion is precisely mapped using standardized analysis and optimized thresholds. • The model achieved high rebar picking accuracy and accurate corrosion mapping. • The proposed framework advances strides toward a smart bridge inspection. [ABSTRACT FROM AUTHOR]

Ground Penetrating Radar (GPR) is a geophysical tool widely used for near-surface detection and imaging, but its effectiveness in identifying defects behind reinforced concrete linings is often reduced by electromagnetic shielding and rebar clutter. This paper presents a systematic workflow that enhances defect echo detection by suppressing rebar clutter. A synthetic dataset, specifically tailored to double-layer rebar meshes, is constructed to develop an optimized Residual Channel Attention Network (RCAN) for effective rebar clutter suppression. Data processed through this network undergoes imaging via a Reverse Time Migration (RTM) algorithm enhanced by Poynting vector decomposition. Analyses of synthetic data highlight the impact of rebar mesh on concealed defects and validate the approach presented. Field validations on full-scale tunnel linings confirm the algorithm's robustness and applicability, demonstrating its potential for accurately imaging concealed defects behind reinforced concrete linings. [Display omitted] • Systematic workflow for precise imaging of concealed defects behind reinforced concrete linings. • An RCAN is established for suppression of rebar clutter in GPR data. • A comprehensive dataset, comprising pairs of synthetic GPR data, is established for training the network. • Enhancement of the RTM algorithm for high-quality GPR Imaging using Poynting vector decomposition. • Field experiments validate the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

This contribution aims to interpret the producers and the paleoenvironmental context of Holocene rodent burrows (and associated ichnofossils) from the Late Pleistocene-Holocene Meaucó Formation, central La Pampa Province, Argentina. Fieldwork included a detailed sedimentary logging, a ground penetrating radar survey and documentation of the fossil burrow systems. The Meaucó Formation rest on erosive unconformity over the Upper Miocene-Lower Pliocene Cerro Azul Formation and display a vertical change from eolian dunes that become sparser up section (as imaged by ground penetrating radar) and were capped by a paleosol. The paleosol is covered by recent eolian dune and interdune deposits. The fossil rodent burrows occur up to 1.7 m below the paleosol and share several morphologic features with modern Ctenomyidae burrows, except the high slope of entrance and internal ramps, and the maximum depth of burrows. To explain these differences, it is proposed that the burrows were excavated by ctenomyids in ancient sloping surfaces of eolian dunes, which resulted in increased inclination and apparent maximum depth of the systems. This is an example of influence of environmental conditions on the architecture of rodent burrows, and can be of help when interpreting other similar fossil examples. The paleosol community associated with the fossil vertebrate burrows also included other organisms recorded by their trace fossils: horses (Hippipeda isp.), a scrubby vegetation (rhizoliths), coleoptera or spiders (Skolithos linearis), cicada nymphs (Feoichnus challa) and ants (Daimoniobarax isp.). • Extant Ctenomyidae burrow systems are subhorizontal. • Fossil Ctenomyidae burrows with high inclination related to eolian dunes. • Changes in burrow system architecture reflect environmental fluctuation. • Eolian dunes inferred from ground penetrating radar sections and grainsize analysis. • Diverse associated invertebrate and plant trace fossils. [ABSTRACT FROM AUTHOR]

Achieving high horizontal resolution is crucial for general non-destructive testing (NDT) applications, and in the domain of ground penetrating radar (GPR), it can be more challenging due to inefficient transmissions of electromagnetic waves into and through complex material under test (MUT). In this study, we showcase the validation results of our recently designed ultra-wideband metasurface (UWM) in improving the horizontal resolution for GPR B-Scan images. This UWM has an ultra-wide working frequency band (100%) from 1 to 3 GHz, in which high-frequency GPR signals can be enhanced and transmitted into MUT. Our fourteen-day consecutive GPR experiments demonstrate that two buried pipes with an edge-to-edge spacing of 8 cm that are hard to distinguish by traditional GPR surveys can be visually identified by depositing the UWM atop the MUT. The underlying mechanism is the sustained and improved transmission of high-frequency signals into the MUT, enabled by the removal of transmission coupling loss by the UWM at the air–MUT interface and the resulting enhanced transmission of more high-frequency components. Our simulations also provide quantitative analysis of such enhanced behavior with a nominal transmittance increase of 30% ∼ 50%. We believe the horizontal resolution improvement enabled by UWM will open a new corridor for high-resolution GPR system design. • An ultra-wideband metasurface (UWM) is designed for enhanced signal transmission in GPR surveys. • Multi-day GPR surveys validate the horizontal resolution improvement assisted by UWM. • Simulation results showcase the GPR transmittance increase of 30% ∼ 50%. [ABSTRACT FROM AUTHOR]

Imaging of the subsurface in the arid area is one of the well-known application of the synthetic aperture radar (SAR) technology due to the deeply penetration of the longer wavelengths in the sand. In this study, we have investigated the buried/paleochannels signatures in the Jaisalmer, Rajasthan, India using the penetration capabilities of the Microwave data particularly at L band. High resolution Advanced Land Observing Satellite (ALOS) data has been used for the subsurface understanding in the desert area of the Jaisalmer, India. Here, around 20 km northeast direction from the main city, we traced the channels concealed in the Aeolian sediments around Jaisalmer. The paleochannel system drains in the southwest while the main channel approach northward. After the identification of the paleochannel though SAR technology, a ground base technique called Ground penetrating radar (GPR) was used for the verification of the subsurface penetration results. Authentication has been done by using the systematic ground investigation to collect scientific evidence in the Jaisalmer area. Moreover, these results offer new insight about the identification of buried channels in the paleoenvironment context in the Thar desert area. [ABSTRACT FROM AUTHOR]

This study comprises the investigation of the complex and deformed Late Pleistocene sedimentary sequence in western Latvia composed of sandy sediments that are protruded by large-scale clayey silt diapirs and covered by glaciotectonically disturbed discontinuous patches of the Late Weichselian till. We use detailed measurements by ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) combined with borehole data and sedimentological investigations at the Baltic Sea cliffs to map and characterize the large-scale deformation structures and discontinuous till patches. We distinguish the intriguing and previously not detected characteristics of the spatial distribution pattern of discontinuous till layer represented as elongated, up to 150 m long and up to 50 m wide patches, parallel to the seacoast and perpendicular to the latest ice flow direction. The upper surface of till patches is flat and not inclined in any direction that is partially explainable by the postglacial erosion of the Baltic Ice Lake. The possible locations of diapirs inland are drawn from GPR data. We relate the formation of observed large-scale deformations to subglacial diapirism induced by the ice loading of the advancing Apriķi Ice Tongue: clayey silt sediments become loaded and overpressurized, and flowed upwards intruding into the overlying sandy sediments. The initial deposition and deformation of till layer could have been affected by the diapirism process and preferred accretion of till in inter diapir spaces. We demonstrate that the geophysical methods can greatly supplement traditional geological investigations in the field revealing characteristics of deformed sediment sequences that are not recognizable from the outcrop data only and thus can have significant implications on the interpretation of deformation processes. [ABSTRACT FROM AUTHOR]

[Display omitted] In recent years there has been an increasing research interest in the development of airborne-based Ground Penetrating Radar (GPR) systems for safe and fast detection of buried threats such as landmines and Improvised Explosive Devices (IEDs). Compared to other sensors such as metal detectors or magnetometers, GPR is able to detect either metallic and non-metallic targets. Besides, the use of Ultra Wide Band (UWB) radiofrequency hardware allows retrieving high resolution images of the subsoil, thus improving the detection capabilities. Airborne-based GPR systems are affected by uncertainties that need to be characterized and corrected. This contribution focuses on the following three issues: (i) influence of the height information in the GPR-Synthetic Aperture Radar (GPR-SAR) images, determining which sensors provide better quality images; (ii) distortion of the imaged targets in along-track axis due to small tilting of the UWB antennas on board the UAV, proposing a co-registration technique to correct it; and (iii) revision of SVD filtering techniques, assessing a criterion to classify the different eigenimages. The analysis of these issues, as well as the validation of the proposed correction methods, are conducted using measurements taken during validation campaigns of the implemented airborne-based GPR system. For this purpose, two validation scenarios with different soil characteristics have been selected. Metallic and non-metallic targets with different shapes and sizes have been buried in them. In the case of the first scenario (wet loamy soil), detection capabilities improved from 50% (5 out of 10 targets were detected) to 80%. For the second validation scenario (loamy soil, but less humid than the first scenario), not only a 100% detection is achieved, but also the targets are clearly imaged in the GPR-SAR images obtained with the improvements presented in this contribution. [ABSTRACT FROM AUTHOR]

• An assessment method using electromagnetic waves and cone penetration is proposed. • The interface depths in active layer are estimated using the proposed method. • The ground conditions including cavity, groundwater level, and permafrost are predicted. • The prediction results are visually verified using an endoscope. • The proposed method can be a powerful tool for characterizing active layers. This study aims to estimate the interface depth in the active layer using nondestructive electromagnetic methods and cone penetration assessment. Ground penetrating radar (GPR) surveys, time domain reflectometry (TDR) measurements, and dynamic cone penetrometer (DCP) tests are conducted on the active layer. Ny-Ålesund in Svalbard is selected as the study area because of its distinct freeze–thaw cycles. The GPR survey detects the underground interfaces, and the relative permittivity of the ground is estimated using TDR measurement. Ground conditions are predicted using the depth-dependent relative density acquired from the DCP test. The results show that the interface depths estimated by GPR and TDR match well with the actual depths. The predictions of the cavity, groundwater level, and frozen layer using GPR polarity comparison are verified using an endoscope to match the actual ground conditions. This study demonstrates that GPR, TDR, and DCP tests may be robust tools for characterizing active layers. [ABSTRACT FROM AUTHOR]

Ground penetrating radar (GPR) has emerged as a powerful non-destructive imaging tool and widely used technology for subsurface imaging across various fields. However, one of the significant challenges in GPR data analysis is clutter, which arises from various sources such as surface roughness, antenna ringing, and electromagnetic interference. This clutter obscures the desired subsurface information and hinders interpretation. In recent years, significant progress has been made in developing clutter removal techniques to enhance the quality and reliability of GPR data. This comprehensive review paper presents an in-depth examination of clutter removal techniques for GPR images, categorizing them into traditional signal processing methods, dictionary learning techniques, low-rank and sparse-based algorithms, and deep learning-based approaches. By discussing the principles, advantages, and limitations of each technique, along with their applications and recent advancements, this review aims to provide insights into the state-of-the-art in clutter removal for GPR imagery, addressing key challenges and paving the way for future research directions in this critical domain. [ABSTRACT FROM AUTHOR]

Northeast-trending linear topographic ridges in Pliocene and Quaternary sediments adjacent to the New Madrid seismic zone (NMSZ), intraplate North America, have been long speculated to be neotectonic landforms related to reactivation of basement faults of the eastern Mississippi Valley Rift margin. Earthquake epicenters and paleoseismological studies show that eastern rift margin faults (ERMF) were active during late Quaternary south of a restraining bend in the Mississippi Valley Rift fault complex, but the ERMF zone north of the restraining bend (ERM-N) and underlying the linear ridges is seismically quiescent. A previous P-wave seismic reflection survey across the most prominent linear ridge (Rives lineament) revealed that it overlies a horst in Eocene sediment. To ascertain whether the Rives lineament could have been produced by surface faulting/folding, we collected electrical resistivity tomography (ERT) and ground penetrating radar (GPR) profiles to image the ridge's shallow subsurface features. We interpret shallow folding and faulting of late Pleistocene sediment in our ERT and GPR images. Additionally, convexity of multiple topographic profiles of scarps along margins of the Rives lineament was quantified and compared to the convexity of profiles of known neotectonic scarps and of fluvial terrace riser profiles within the region. Comparison of these profiles reveals a high degree of similarity between the scarps along the Rives lineament margins and the Holocene Reelfoot thrust scarp. When combined, our results strongly suggest late Pleistocene or Holocene folding and faulting created this ridge despite its current seismic quiescence, and thus they provide useful insight for assessing the seismic hazard potential of quiescent faults in strike-slip systems in general. We conclude that the late Quaternary series of movements documented on the Reelfoot thrust was initiated to accommodate crustal shortening after transpressional fault movements on the ERM-N became inactive in late Pleistocene or early Holocene and that movement along the ERM-N may resume if the Reelfoot thrust has an interval of inactivity in the future. Our results suggest how fault interactions within a strike-slip system can change, making faults with significant amounts of seismic potential appear as though they are inactive. • Linear ridges in Quaternary sediment express intraplate neotectonics. • Scarp morphology comparisons discriminate tectonic and erosional scarps. • Late Pleistocene folding and faulting are revealed by shallow geophysics. [ABSTRACT FROM AUTHOR]